Epoxy resin composition, curable composition, cured product, prepreg and composite material

Abstract

To provide an epoxy resin composition which imparts excellent impact strength resistance to a cured product.SOLUTION: An epoxy resin composition contains a component (A) which contains a bisphenol type epoxy resin represented by general formula (1) and has an epoxy equivalent in a range of 180-700, and a bisphenol type epoxy resin (B) which has an epoxy equivalent in a range of 200-560 and is represented by general formula (3), wherein a ratio (Wa) / (Wb) of a weight Wa of the component (A) to a weight Wb of the biphenol type epoxy resin (B) is 72 / 28 to 85 / 15.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an epoxy resin composition, a curable composition, a cured product, a prepreg, and a composite material. [Background technology]

[0002] Epoxy resins are widely used in fields such as electrical and electronic components and structural materials due to their workability and the excellent electrical properties, heat resistance, adhesiveness, moisture resistance (water resistance) and other properties of their cured products (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 5348740 Summary of the Invention [Problem to be solved by the invention]

[0004] Because epoxy resins and their cured products have the excellent properties described above, they have recently been considered for use as materials for parts in automobiles, drones, and nursing care robots. These applications are expected to be used in environments where they will be subject to impacts, so they require higher impact resistance. An object of the present invention is to provide an epoxy resin composition that imparts excellent impact strength to the cured product. [Means for solving the problem]

[0005] The present inventors have conducted research to achieve the above object and have arrived at the present invention. Specifically, the present invention provides an epoxy resin composition comprising a component (A) containing a bisphenol-type epoxy resin represented by the following general formula (1) and having an epoxy equivalent in the range of 180 to 700, and a biphenol-type epoxy resin (B) represented by the following general formula (3) and having an epoxy equivalent in the range of 200 to 560, wherein the ratio (Wa) / (Wb) of the weight (Wa) of component (A) to the weight (Wb) of the biphenol-type epoxy resin (B) is 72 / 28 to 85 / 15; a curable composition containing the epoxy resin composition and a curing agent and / or a curing accelerator; a cured product obtained by curing the curable composition; a prepreg containing the curable composition and reinforcing fibers; and a composite material obtained by curing the prepreg.

[0006] [ka]

[0007] In formula (1), R 1 are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms, and R 2 is a structural moiety represented by any one of the following general formulae (2-1) to (2-7), and n is the number of moles of the group represented by the following general formula (2A) added, which is a number of 0.1 or more.

[0008] [ka]

[0009] In formula (2-2), R 3 are each independently either an alkyl group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms.

[0010] [ka]

[0011] In formula (2A), R 1 are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms, and R2 is a structural moiety represented by any one of the above general formulas (2-1) to (2-7).

[0012] [ka]

[0013] In formula (3), R 4 are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms, and R 5 is an alkylene group having 2 to 6 carbon atoms, and m is R 5 O or OR 5 and each independently represents the number of moles of 1 or more. [Effects of the Invention]

[0014] According to the present invention, it is possible to provide an epoxy resin composition that imparts excellent impact resistance to the cured product. DETAILED DESCRIPTION OF THE INVENTION

[0015] <Epoxy resin composition> The epoxy resin composition of the present invention contains component (A), which contains a bisphenol-type epoxy resin represented by the following general formula (1) and has an epoxy equivalent in the range of 180 to 700, and component (B), which is a biphenol-type epoxy resin represented by the general formula (3) and has an epoxy equivalent in the range of 200 to 560. The bisphenol-type epoxy resin contained in the component (A) is represented by the following general formula (1): Hereinafter, "component (A) containing a bisphenol-type epoxy resin represented by general formula (1) and having an epoxy equivalent in the range of 180 to 700" will also be referred to as "component (A)".

[0016] [ka]

[0017] In general formula (1), R 1are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms. Examples of alkyl groups having 1 to 4 carbon atoms include methyl groups, ethyl groups, linear or branched propyl groups, and linear or branched butyl groups. Examples of alkoxy groups having 1 to 4 carbon atoms include methoxy groups, ethoxy groups, linear or branched propoxy groups, and linear or branched butoxy groups. R 1 is preferably a hydrogen atom.

[0018] R 2 is a structural moiety represented by any one of the following general formulas (2-1) to (2-7). 3 are each independently either an alkyl group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms. As the alkyl group having 1 to 4 carbon atoms and the alkoxy group having 1 to 4 carbon atoms, R 1 Examples of the groups include the same groups as those exemplified in R 2 is preferably a structural moiety represented by general formula (2-2), and more preferably R 3 is the structural moiety that is a methyl group.

[0019] [ka]

[0020] In general formula (1), n ​​is a number equal to or greater than 0.1. n is the number of moles of the group represented by general formula (2A) below, and is a number equal to or greater than 0.1. n is the number of moles of the group represented by general formula (2A) per molecule of the bisphenol epoxy resin represented by general formula (1), and may be a decimal number. The group represented by general formula (2A) is the group in parentheses in general formula (1). n is preferably 0.1 to 10.0, more preferably 0.1 to 6.0. An example of a case where n is a decimal number will be described below. For example, in an embodiment in which component (A) contains a compound in general formula (1) having one group represented by general formula (2A) and a compound in general formula (1) having zero groups represented by general formula (2A) in a molar ratio of 1:9, the number of groups represented by general formula (2A) per molecule of the bisphenol epoxy resin represented by general formula (1) is 0.1. The formula for calculating n in the above case is as follows: n = (1 × 1 + 0 × 9) / (1 + 9)

[0021] [ka]

[0022] In general formula (2A), R 1 are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms, and R 2 is a structural moiety represented by any one of the general formulae (2-1) to (2-7). 1 and R 2 are R in general formula (1), 1 and R 2 is the same as

[0023] The epoxy equivalent of component (A) containing a bisphenol-type epoxy resin represented by general formula (1) is 180 to 700. When the epoxy equivalent of component (A) is within the above range, excellent impact resistance can be exhibited in the cured product of the curable composition containing the epoxy resin composition. When the epoxy equivalent is less than 180 or more than 700, the impact resistance of the cured product may be insufficient. The epoxy equivalent of component (A) is preferably 200 to 700, more preferably 250 to 600.

[0024] In the present invention, the epoxy equivalent of an epoxy resin refers to the mass of a resin containing one equivalent of epoxy groups, and can be measured by the method specified in JIS K 7236. When two or more epoxy resins are used, the epoxy equivalent of a mixture containing two or more epoxy resins can be calculated as follows. For example, when W1 g of epoxy resin 1 having an epoxy equivalent of EE1 and W2 g of epoxy resin 2 having an epoxy equivalent of EE2 are used, the epoxy equivalent EEm of the mixture of epoxy resin 1 and epoxy resin 2 can be calculated by the following formula (X). EEm=(W1+W2) / {(W1 / EE1)+(W2 / EE2)} (X)

[0025] In the present invention, the bisphenol-type epoxy resin represented by general formula (1) may be used as the component (A) either singly or in combination. When two or more bisphenol-type epoxy resins are used as the component (A), the epoxy equivalent of the mixture of the two or more bisphenol-type epoxy resins may be in the range of 180 to 700, and the mixture may contain a bisphenol-type epoxy resin whose epoxy equivalent is outside the above range. Preferably, the component (A) consists of two or more bisphenol-type epoxy resins.

[0026] The bisphenol-type epoxy resin contained in component (A) can be produced using various bisphenol compounds and epihalohydrin, etc. Specific production methods include, for example, a method in which a bisphenol compound is reacted with an epihalohydrin to obtain a diglycidyl ether compound, which is then reacted with a bisphenol compound (Method 1), and a method in which a bisphenol compound is reacted with an epihalohydrin to directly obtain the target epoxy resin (Method 2). Method 1 is preferred because the reaction is easy to control and the epoxy equivalent of the resulting epoxy resin can be easily adjusted.

[0027] The bisphenol compound used in Method 1 or 2 may be, for example, a compound represented by the following general formula (1a): As the epihalohydrin, epichlorohydrin or the like may be used.

[0028] [ka]

[0029] In formula (1a), R 1 and R 2 are R in general formula (1), 1 and R 2 The compound represented by general formula (1a) can be selected depending on the type of the target bisphenol epoxy resin [compound represented by general formula (1)].

[0030] The bisphenol-type epoxy resin represented by general formula (1) contained in the component (A) is preferably a bisphenol A-epichlorohydrin condensate. As the bisphenol-type epoxy resin represented by general formula (1), commercially available products may be used. Examples of commercially available bisphenol-type epoxy resins include "jER1004," "jER1001," and "jER828" manufactured by Mitsubishi Chemical Corporation.

[0031] The biphenol-type epoxy resin (B) is a compound represented by the following general formula (3): Hereinafter, the "biphenol-type epoxy resin (B)" will also be referred to as the "component (B)."

[0032] [ka]

[0033] In general formula (3), R 4 are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms. Examples of alkyl groups having 1 to 4 carbon atoms include methyl groups, ethyl groups, linear or branched propyl groups, and linear or branched butyl groups. Examples of alkoxy groups having 1 to 4 carbon atoms include methoxy groups, ethoxy groups, linear or branched propoxy groups, and linear or branched butoxy groups. R 4 is preferably a hydrogen atom.

[0034] R 5 is an alkylene group having 2 to 6 carbon atoms. Specific examples of the alkylene group having 2 to 6 carbon atoms include a methylene group, an ethylene group, a linear or branched propylene group, a linear or branched butylene group, a linear or branched pentylene group, and a linear or branched hexylene group. R 5 R is preferably a linear or branched propylene group. 5 If there are multiple (m is 2 or more), R 5 may be the same or different. In the general formula (3), m is R 5 O or OR 5 Each of the two m's represents the number of moles of R per molecule of the biphenol-type epoxy resin (B) represented by the general formula (3), and each m is independently a number of 1 or more. 5 Number of moles of O and OR 5 Each m is preferably an integer of 1 to 7, and the sum of the two m's is more preferably 2 to 14.

[0035] The biphenol-type epoxy resin (B) represented by general formula (3) has an epoxy equivalent in the range of 200 to 560. When the epoxy equivalent of the biphenol-type epoxy resin (B) is within the above range, the cured product obtained by curing the epoxy resin composition can exhibit excellent impact resistance. When the epoxy equivalent is less than 200 or more than 560, the impact resistance may be insufficient. The epoxy equivalent of the biphenol-type epoxy resin (B) is preferably 200 to 556, more preferably 300 to 500.

[0036] In the present invention, the biphenol-type epoxy resin (B) may be used singly or in combination of two or more. When two or more biphenol-type epoxy resins (B) are used, the epoxy equivalent of the mixture of the two or more biphenol-type epoxy resins may be in the range of 200 to 560, and the mixture may contain a biphenol-type epoxy resin whose epoxy equivalent is outside the above range.

[0037] The biphenol-type epoxy resin (B) can be obtained by diglycidyl etherifying an alkylene oxide (AO) adduct of biphenol, which is obtained by adding an alkylene oxide (AO) having 2 to 6 carbon atoms to a biphenol compound represented by the following general formula (3a):

[0038] [ka]

[0039] R in general formula (3a) 4 is R in general formula (3) 4The alkylene oxide constituting the AO adduct of biphenol [the alkylene oxide having 2 to 6 carbon atoms to be added to the compound represented by general formula (3a)] includes ethylene oxide (hereinafter abbreviated as EO), 1,2-propylene oxide (hereinafter abbreviated as PO), 1,2-butylene oxide, 1,2-pentylene oxide, and 1,2-hexylene oxide. These may be used alone or in combination of two or more. The AO is preferably an alkylene oxide having 2 to 4 carbon atoms, more preferably PO.

[0040] The epoxy equivalent of the epoxy resin composition of the present invention is preferably in the range of 250 to 600, more preferably 255 to 580, from the viewpoint of excellent impact resistance.

[0041] In the epoxy resin composition of the present invention, the ratio (Wa) / (Wb) of the weight (Wa) of the component (A) to the weight (Wb) of the biphenol-type epoxy resin (B) is 72 / 28 to 85 / 15. When the ratio (Wa) / (Wb) of the weight (Wa) of the component (A) to the weight (Wb) of the biphenol-type epoxy resin (B) is within the above range, the curable composition containing the epoxy resin composition can exhibit excellent impact resistance in a cured product. When the (Wa) / (Wb) ratio is less than 72 / 28 or more than 85 / 15, the impact resistance of the cured product of the curable composition containing the epoxy resin composition may be insufficient. The epoxy resin composition of the present invention can be used as a curable composition together with a curing agent and / or a curing accelerator.

[0042] <Curable composition> The curable composition of the present invention contains the epoxy resin composition of the present invention and a curing agent and / or a curing accelerator.

[0043] Examples of the curing agent (C) and the curing accelerator (D) include polyamine compounds, amide compounds, acid anhydrides, phenolic hydroxyl group-containing resins, phosphorus compounds, imidazole compounds, imidazoline compounds, urea compounds, organic acid metal salts, Lewis acids, and amine complex salts. Hereinafter, the "curing agent (C)" may be referred to as the "(C) component," and the "curing accelerator (D)" may be referred to as the "(D) component." Specific examples of these include those described in Japanese Patent No. 6721855. An example is shown below.

[0044] Examples of polyamine compounds include aliphatic amine compounds (e.g., trimethylenediamine, ethylenediamine, etc.), alicyclic and heterocyclic amine compounds (e.g., piperidine, piperazine, menthanediamine, isophoronediamine, methylmorpholine, ethylmorpholine, etc.), aromatic amine compounds (e.g., phenylenediamine, diaminodiphenylmethane, diaminodiphenylsulfone, benzylmethylamine, dimethylbenzylamine, m-xylenediamine, pyridine, etc.), and modified amine compounds (e.g., epoxy compound-added polyamines). Examples of the amide compound include dicyandiamide and polyamidoamine (e.g., those obtained by reacting an aliphatic dicarboxylic acid such as succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, or azelaic acid, a carboxylic acid compound such as a fatty acid or dimer acid with an aliphatic polyamine or a polyamine having a polyoxyalkylene chain). Examples of acid anhydrides include phthalic anhydride, trimellitic anhydride, pyromellitic anhydride, maleic anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylnadic anhydride, hexahydrophthalic anhydride, and methylhexahydrophthalic anhydride. Examples of the phenolic hydroxyl group-containing resin include phenol novolac resin, cresol novolac resin, aromatic hydrocarbon formaldehyde resin-modified phenol resin, and dicyclopentadiene phenol addition type resin. Examples of the phosphorus compound include alkyl phosphines such as ethylphosphine and butylphosphine, primary phosphines such as phenylphosphine, dialkyl phosphines such as dimethylphosphine and dipropylphosphine, secondary phosphines such as diphenylphosphine and methylethylphosphine, and tertiary phosphines such as trimethylphosphine, triethylphosphine and triphenylphosphine. Examples of the imidazole compound include imidazole, methylimidazole, and ethylimidazole. Examples of the imidazoline compound include 2-methylimidazoline and 2-phenylimidazoline. Examples of the urea compound include aromatic dimethylurea compounds (p-chlorophenyl-N,N-dimethylurea, 3-phenyl-1,1-dimethylurea, 3-(3,4-dichlorophenyl)-N,N-dimethylurea, and N-(3-chloro-4-methylphenyl)-N',N'-dimethylurea).

[0045] Commercially available curing agents (C) and curing accelerators (D) may be used, such as dicyandiamide (manufactured by Mitsubishi Chemical Corporation under the trade name "DICY7") and aromatic dimethylurea (manufactured by San-Apro Co., Ltd. under the trade name "U-CAT 3512T").

[0046] The curing agent (C) is preferably at least one compound selected from the group consisting of aromatic amine compounds, acid anhydrides, imidazole compounds, and dicyandiamide, and more preferably contains dicyandiamide. The curing accelerator (D) preferably contains a urea compound, more preferably aromatic dimethylurea.

[0047] When the curing agent (C) is used in the present invention, the amount used is preferably from 0.5 to 10% by weight, more preferably from 1 to 7% by weight, based on the weight of the curable composition. When a curing agent having a functional group capable of reacting with an epoxy group is used as the curing agent (C), it is preferable to use the curing agent so that the amount of the functional group in the curing agent is in the range of 0.4 to 1.0 moles per mole of epoxy group in the epoxy resin component [component (A), component (B), and other epoxy resin (E) added as needed (details will be described later)].

[0048] In the present invention, when the curing accelerator (D) is used, the amount used is preferably from 0.5 to 10% by weight, more preferably from 1 to 7% by weight, based on the weight of the curable composition.

[0049] The curable composition of the present invention may contain an epoxy resin other than components (A) and (B). Examples of other epoxy resins (E) [also referred to as component (E)] include novolac-type epoxy resins such as phenol novolac-type, naphthol novolac-type, cresol novolac-type, and phenol-cresol co-condensed novolac-type, urethane-modified epoxy resins, and triphenylmethane-type epoxy resins.

[0050] The curable composition of the present invention may contain components other than the components (A) to (E). Examples of other components include organic solvents, ultraviolet absorbers, antioxidants, silicon-based additives, fluorine-based additives, flame retardants, plasticizers, silane coupling agents, organic beads, inorganic fine particles, inorganic fillers, rheology control agents, defoamers, anti-fogging agents, and colorants. These components can be added in any amount depending on the desired performance.

[0051] The curable composition of the present invention can be prepared by uniformly mixing component (A), component (B), component (C), and / or component (D), and, if necessary, component (E) and the other components described above, using an apparatus selected from a pot mill, ball mill, bead mill, roll mill, homogenizer, super mill, homodisper, universal mixer, Banbury mixer, kneader, and the like.

[0052] <Cured product> The cured product of the present invention is obtained by curing the curable composition of the present invention. The cured product of the present invention can be produced, for example, by placing the curable composition prepared by the above-mentioned method in a mold or the like of a desired shape and heating it at 120 to 140°C for 1 to 3 hours. The temperature conditions and heating time when producing the cured product can be appropriately selected taking into consideration the type and amount of resin contained in the composition.

[0053] The cured product of the curable composition of the present invention has excellent impact resistance and is therefore suitable, for example, as a component material for products expected to be used in environments where shocks are present. Examples of products expected to be used in environments where shocks are present include automobiles, drones, and nursing care robots. In addition to the above-mentioned uses, the cured product of the present invention may also be used for paints, coating agents, molding materials, insulating materials, sealants, sealing agents, and fiber binders.

[0054] <Prepreg> The prepreg of the present invention comprises the curable composition of the present invention and reinforcing fibers. The prepreg of the present invention is a prepreg comprising the curable composition of the present invention as a matrix resin. The prepreg of the present invention may contain a catalyst, if necessary, in addition to the reinforcing fibers and the curable composition of the present invention. As the catalyst, those exemplified as the curing agent (C) and curing accelerator (D) above may be used, or known curing agents and curing accelerators for epoxy resins, such as those described in JP-A-2005-213337, may also be used.

[0055] Examples of reinforcing fibers include fiber bundles obtained by treating fibers with a fiber sizing agent and fiber products obtained by processing the fiber bundles. Known and commercially available fiber sizing agents can be used. Examples of commercially available fiber sizing agents include the "Chemiethylene" series manufactured by Sanyo Chemical Industries, Ltd.

[0056] Examples of fibers to be treated with the fiber sizing agent include known fibers such as glass fibers, carbon fibers, aramid fibers, ceramic fibers, metal fibers, mineral fibers, rock fibers, and slag fibers (e.g., those described in WO 2003 / 47830). From the viewpoint of the strength of the composite material, carbon fibers are preferred. One type of fiber may be used alone, or two or more types may be used in combination.

[0057] Fiber treatment methods include spraying and dipping. The amount (wt%) of the fiber sizing agent attached to the fibers is preferably 0.05 to 5 wt%, more preferably 0.1 to 3.0 wt%, based on the weight of the fibers. Within this range, the strength of the composite is further improved.

[0058] The fiber products are produced by processing the fiber bundles, and include woven fabrics, knitted fabrics, nonwoven fabrics (felt, mats, paper, etc.), chopped fibers, milled fibers, and the like.

[0059] The prepreg of the present invention can be produced by a method of thermally melting the curable composition of the present invention (melting temperature: 60 to 150°C) and impregnating fibers with the composition, or by a method of impregnating fibers with the curable composition of the present invention diluted with a solvent (acetone, methyl ethyl ketone, methyl isobutyl ketone, toluene, xylene, ethyl acetate, etc.). When a method using a solvent is employed, it is preferable to remove the solvent by drying the prepreg.

[0060] The weight ratio of the curable composition to the fibers (curable composition / fibers) is preferably 10 / 90 to 90 / 10, more preferably 20 / 80 to 70 / 30, and particularly preferably 30 / 70 to 60 / 40, from the viewpoint of molded body strength, etc. When a catalyst is contained, the content (wt %) of the catalyst relative to the curable composition is preferably 0.01 to 10, more preferably 0.1 to 5, and particularly preferably 1 to 3, from the viewpoint of molded body strength, etc.

[0061] <Composite materials> The composite material of the present invention is obtained by curing the prepreg of the present invention. The composite material can be obtained, for example, by heat-molding and curing the prepreg of the present invention. Curing does not need to be complete, but it is preferable that the composite material be cured to an extent that it can maintain its shape. The heat-molding method is not particularly limited, and examples include a filament winding molding method (a method in which prepreg sheets are wound around a rotating mandrel under tension and then heat-molded), a press molding method (a method in which prepreg sheets are stacked and then heat-molded), an autoclave method (a method in which prepreg sheets are pressed against a mold under pressure and then heat-molded), and a method in which chopped fiber or milled fiber is mixed with a matrix resin and then injection-molded. [Example]

[0062] The present invention will be further explained below with reference to examples and comparative examples, but the present invention is not limited to these.

[0063] <Production Example 1: Production of 4,4'-dihydroxybiphenyl PO adduct (b1)> A pressure-resistant reactor equipped with a stirrer, a heating / cooling device, and a dropping bomb was charged with 186.2 parts by weight (1 mol) of a biphenol compound (4,4'-dihydroxybiphenyl [Tokyo Chemical Industry Co., Ltd.]), 130.3 parts by weight of methyl ethyl ketone, and 1 part by weight of potassium hydroxide, and the atmosphere was purged with nitrogen. The temperature was raised to 110°C, and 116 parts by weight (2 mol) of propylene oxide was added dropwise over 19 hours while adjusting the pressure to 0.5 MPa or less. The mixture was then aged at 110°C for 6 hours. The methyl ethyl ketone was then distilled off under reduced pressure at 85°C and -0.1 MPa, yielding the 4,4'-dihydroxybiphenyl-PO adduct (b1).

[0064] <Production Example 2: Production of 4,4'-dihydroxybiphenyl PO adduct (b2)> A PO adduct (b2) of 4,4'-dihydroxybiphenyl was obtained in the same manner as in Production Example 1, except that the amount of PO was changed from 116 parts by weight (2 parts by mole) to 406 parts by weight (7 parts by mole).

[0065] <Production Example 3: Production of 4,4'-dihydroxybiphenyl PO adduct (b3)> A PO adduct (b3) of 4,4'-dihydroxybiphenyl was obtained in the same manner as in Production Example 1, except that the amount of PO was changed from 116 parts by weight (2 parts by mole) to 812 parts by weight (14 parts by mole).

[0066] <Production Example 4: Production of biphenol-type epoxy resin (B-1)> A reaction vessel equipped with a stirrer, temperature control means, and a wet mill (attached to the outside of the reaction vessel) was charged with 151 parts by weight of 4,4'-dihydroxybiphenyl PO adduct (b1), 278 parts by weight of epichlorohydrin, and 30 parts by weight of cyclohexane, and the reaction vessel was conditioned under a nitrogen atmosphere (oxygen concentration: 730 ppm). 112 parts by weight of granular potassium hydroxide in a nitrogen atmosphere at 19°C was intermittently added over 5 hours at 19 to 29°C. The mixture was then reacted and aged for 5 hours at 25 to 29°C, and the (b1) was glycidyl etherified. The vessel was then cooled to 16°C, and 370.4 parts by weight of 23°C water was added at 20-28°C. The mixture was stirred for 0.5 hours. After allowing the mixture to stand at 17°C for 0.5 hours, the lower (aqueous) layer was removed. 12 parts by weight of Kyoward 600 (Kyowa Chemical Industry Co., Ltd.; alkali adsorbent) was added to the remaining upper (organic) layer and stirred at 80°C for 0.5 hours. After filtration using Radiolite #700 (Kyowa Chemical Industry Co., Ltd.; diatomaceous earth filter aid), the mixture was heated to 110°C under reduced pressure (-0.1 MPa) and the epichlorohydrin and cyclohexane mixture was distilled off to obtain biphenol-type epoxy resin (B-1). The epoxy equivalent of biphenol-type epoxy resin (B-1) was measured according to the method specified in JIS K7236.

[0067] <Production Example 5: Production of biphenol-type epoxy resin (B-2)> A biphenol-type epoxy resin (B-2) was obtained by the same procedure as in Production Example 4, except that 296 parts by weight of a 4,4'-dihydroxybiphenyl-PO adduct (b-2) was used instead of 151 parts by weight of the 4,4'-dihydroxybiphenyl-PO adduct (b-1) in Production Example 4. The epoxy equivalent of the biphenol-type epoxy resin (B-2) was measured in the same manner as in (B-1) above.

[0068] <Production Example 6: Production of biphenol-type epoxy resin (B-3)> A biphenol-type epoxy resin (B-3) was obtained by the same procedure as in Production Example 4, except that 499 parts by weight of a 4,4'-dihydroxybiphenyl-PO adduct (b-3) was used instead of 151 parts by weight of the 4,4'-dihydroxybiphenyl-PO adduct (b-1). The epoxy equivalent of the biphenol-type epoxy resin (B-3) was measured in the same manner as in (B-1).

[0069] <Examples 1 to 5 and Comparative Examples 1 and 2> (Preparation of Curable Composition) The bisphenol-type epoxy resins (A-1), (A-2), and (A-3), the biphenol-type epoxy resins (B-1) to (B-3) or (B'-1), the curing agent (C-1), and the curing accelerator (D-1) in the amounts (parts by weight) shown in Table 1 were mixed using a stirring defoamer (THINKY Corporation, ARV-930TWIN) at 1400 rpm and 100°C for 3 minutes to obtain a curable composition.

[0070] The components used in the examples and comparative examples are as follows: The epoxy equivalents of the epoxy resins (A-1), (A-2), and (A-3) were measured in the same manner as for the epoxy resin (B-1). In Table 1, the "Epoxy equivalent of component (A)" and "Epoxy equivalent of component (B)" columns indicate the epoxy equivalent of the compound when one type of compound is used, and the epoxy equivalent of the mixture of two or more compounds when two or more types of compounds are used. In Table 1, the "Epoxy equivalent of epoxy resin composition" column indicates the epoxy equivalent of the mixture of components (A) and (B). The epoxy equivalent of the mixture was calculated using the above formula (X). (A-1): Bisphenol A epichlorohydrin condensate ["jER1004" manufactured by Mitsubishi Chemical Corporation, epoxy equivalent: 911] (A-2): Bisphenol A epichlorohydrin condensate ["jER1001" manufactured by Mitsubishi Chemical Corporation, epoxy equivalent: 479] (A-3): Bisphenol A epichlorohydrin condensate ["jER828" manufactured by Mitsubishi Chemical Corporation, epoxy equivalent: 186] (B-1): Biphenol-type epoxy resin (PO 2 moles added) obtained in Production Example 1 (epoxy equivalent: 207.1) (B-2): Biphenol-type epoxy resin (PO 10 moles added) obtained in Production Example 2 (epoxy equivalent: 352.2) (B-3): Biphenol-type epoxy resin (14 moles of PO added) obtained in Production Example 3 (epoxy equivalent: 555.6) (C-1): Dicyandiamide ["DICY7" manufactured by Mitsubishi Chemical Corporation] (D-1): Aromatic dimethylurea [U-CAT 3512T, manufactured by San-Apro Co., Ltd.]

[0071] (Preparation and evaluation of cured products) The curable compositions of Examples 1 to 5 and Comparative Examples 1 and 2 were placed in a mold for preparing test specimens (unnotched test specimens) of the size specified in JIS K7110 (ISO180) and heated at 130°C for 1 hour to obtain sheet-like cured products measuring 4 mm in thickness, 80 mm in length, and 10 mm in width. These cured products were used as test specimens. These test specimens were evaluated by the following performance tests. The results are shown in Table 1.

[0072] <Performance test: Evaluation of impact resistance of cured product> In accordance with the method specified in JIS K-7110, an Izod impact test was conducted to measure the impact strength (unit: kJ / m 2 The larger the value, the better the impact resistance.

[0073] <Performance test: Evaluation of impact resistance of composite materials> (Prepreg production) The curable compositions of Examples 1 to 5 and Comparative Examples 1 and 2 were applied to release paper using a knife coater to produce two resin films. Carbon fibers treated with a sizing agent (fineness 800 tex, number of filaments 12,000, sizing agent "Chemiethylene FS-6" manufactured by Sanyo Chemical Industries, Ltd.) were aligned in one direction in a sheet-like configuration to produce a prepreg. Next, one of the resin films was placed on each side of the carbon fibers treated with the sizing agent, and the resulting prepreg was pressurized and heated at a temperature of 85°C and a pressure of 2 MPa to impregnate the fibers with the thermosetting resin composition, producing a unidirectional prepreg.

[0074] (Impact resistance evaluation) The Charpy impact values ​​of the (fiber-reinforced) composite materials were measured by the following method. The unidirectional prepregs were laminated so that the fiber directions were in the same direction and the thickness of the laminate was approximately 3 mm to produce a laminate.The laminate was then heated and pressurized in an autoclave at 135°C and an internal pressure of 588 kPa for 2 hours to be cured, producing a unidirectional fiber-reinforced composite material. Test pieces measuring 3±0.2 mm in thickness, 10±0.2 mm in width, and 80 mm in length were cut out from each of the fiber-reinforced composite materials obtained. Using these test pieces, a Charpy impact test (without a notch) was carried out by applying a flatwise impact with a weight of 300 kg cm in accordance with the method specified in JIS K7077 (1991), and the impact value (unit: kJ / m 2 ) was measured. The number of measurements was n=5 and the average value was calculated. The results are shown in Table 1. The larger the value, the better the impact resistance.

[0075] [Table 1]

[0076] As shown in Table 1, the cured products of the examples, which used epoxy resin compositions containing component (A) containing a bisphenol-type epoxy resin represented by general formula (1) and having an epoxy equivalent ranging from 180 to 700, and a biphenol-type epoxy resin (B) represented by general formula (3) and having an epoxy equivalent ranging from 200 to 560, with a weight ratio (Wa) / (Wb) of 72 / 28 to 85 / 15, exhibited superior impact resistance compared to the comparative examples. Furthermore, the composite materials of the examples also exhibited superior impact test results compared to the comparative examples. These results demonstrate that the present invention can provide epoxy resin compositions that impart excellent impact resistance to cured products.

Claims

1. The composition contains a component (A) made of a bisphenol-type epoxy resin represented by the following general formula (1) and having an epoxy equivalent in the range of 180 to 700, and a biphenol-type epoxy resin (B) represented by the following general formula (3) and having an epoxy equivalent in the range of 200 to 560, An epoxy resin composition in which the ratio (Wa) / (Wb) of the weight Wa of the component (A) to the weight Wb of the biphenol-type epoxy resin (B) is 72 / 28 to 85 / 15. 【Chemistry 1】 [In the formula, R １ are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms; R ２ is a structural moiety represented by any one of the following general formulas (2-1) to (2-7), and n is the number of moles of the group represented by the following general formula (2A), which is a number of 0.1 or more. 【Chemistry 2】 [In the formula, R ３ are each independently either an alkyl group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms.] 【Transformation 3】 [In the formula, R １ are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms; R ２ is a structural moiety represented by any one of the above general formulas (2-1) to (2-7). 【Chemistry 4】 [In the formula, R ４ are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms; R ５ is an alkylene group having 2 to 6 carbon atoms, and m is R ５ O or OR ５ and each independently represents the number of moles of 1 or more.]

2. 2. The epoxy resin composition according to claim 1, wherein each m in the general formula (3) is an integer of 1 to 7, and the sum of the two m's is 2 to 14.

3. 3. The epoxy resin composition according to claim 1, wherein the epoxy equivalent of the epoxy resin composition is in the range of 250 to 600.

4. A curable composition comprising the epoxy resin composition according to claim 1 or 2, and a curing agent and / or a curing accelerator.

5. The curable composition of claim 4 wherein the curing agent comprises dicyandiamide.

6. A cured product obtained by curing the curable composition according to claim 4.

7. A cured product obtained by curing the curable composition according to claim 5.

8. A prepreg comprising the curable composition according to claim 4 and reinforcing fibers.

9. A prepreg comprising the curable composition according to claim 5 and reinforcing fibers.

10. A composite material obtained by curing the prepreg according to claim 8.

11. A composite material obtained by curing the prepreg according to claim 9.

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