JP2022179390A - Epoxy resin composition, curable composition, cured product, prepreg and composite material - Google Patents

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

The present invention relates to epoxy resin compositions, curable compositions, cured products, prepregs and composite materials.

Epoxy resins are widely used in fields such as electrical and electronic parts and structural materials due to workability and excellent electrical properties, heat resistance, adhesiveness, moisture resistance (water resistance) of cured products thereof (e.g., patent documents 1).

Japanese Patent No. 5348740

Epoxy resins and cured products thereof have excellent properties as described above, and thus their use as materials for parts of automobiles, drones, and care robots has been studied in recent years. Since these applications are expected to be used in an impact environment, higher impact strength is required.
An object of the present invention is to provide an epoxy resin composition that imparts excellent impact strength to its cured product.

The present inventor has arrived at the present invention as a result of conducting studies to achieve the above object.
That is, the present invention comprises a bisphenol type epoxy resin represented by the following general formula (1), a component (A) having an epoxy equivalent in the range of 180 to 700, and the following having an epoxy equivalent in the range of 200 to 560. and a biphenol-type epoxy resin (B) represented by the general formula (3), wherein 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, a curable composition containing the epoxy resin composition, a curing agent and / or a curing accelerator; curing obtained by curing the curable composition A prepreg containing the curable composition and reinforcing fibers; A composite material obtained by curing the prepreg.

In formula (1), R ¹ is 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 represented by the following general formulas (2-1) to ( 2-7), and n is the number of added moles of the group represented by the following general formula (2A), which is 0.1 or more.

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

In formula (2A), each R ¹ is 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 represented by general formulas (2-1) to ( 2-7).

In formula (3), R ⁴ is 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 represents the number of added moles of R ⁵ O or OR ⁵ and is independently 1 or more.

ADVANTAGE OF THE INVENTION According to this invention, the epoxy resin composition which gives the hardened|cured material excellent impact strength can be provided.

<Epoxy resin composition>
The epoxy resin composition of the present invention comprises 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 an epoxy equivalent in the range of 200 to 560. and a biphenol-type epoxy resin (B) represented by a certain general formula (3).
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" is also referred to as "(A) component".

In general formula (1), each R ¹ is independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms. The alkyl group having 1 to 4 carbon atoms includes methyl group, ethyl group, linear or branched propyl group and linear or branched butyl group. The alkoxy group having 1 to 4 carbon atoms includes methoxy group, ethoxy group, linear or branched propoxy group and linear or branched butoxy group. R ¹ is preferably a hydrogen atom.

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

n in the general formula (1) is a number of 0.1 or more. n is the number of moles of groups represented by the following general formula (2A), and is a number of 0.1 or more. n is the number of moles of the group represented by the general formula (2A) per molecule of the bisphenol type epoxy resin represented by the 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 when n is a decimal will be described. For example, the component (A) is a compound in which the number of groups represented by the general formula (2A) in the general formula (1) is 1, and a group represented by the general formula (2A) in the general formula (1) and a compound having a number of 0 at a ratio of 1:9 (molar ratio), a group represented by the general formula (2A) per molecule of the bisphenol-type epoxy resin represented by the 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)

In general formula (2A), R ¹ is 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 the general formula (2-1) to It is a structural site represented by any one of (2-7). R ¹ and R ² in formula (2A) are the same as R ¹ and R ² in general formula (1), respectively.

The epoxy equivalent of the component (A) containing the bisphenol type epoxy resin represented by the general formula (1) is 180-700. When the epoxy equivalent of the 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. If 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 200-700, more preferably 250-600.

In the present invention, the epoxy equivalent of an epoxy resin refers to the mass of a resin containing one equivalent of an epoxy group, and can be measured by the method specified in JISK7236.
When using two or more epoxy resins, 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)

In the present invention, the bisphenol type epoxy resin represented by the general formula (1) may be used singly or in combination of two or more as the component (A). 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 epoxy equivalent of the mixture is in the above range. It may also contain a bisphenol-type epoxy resin. The component (A) is preferably composed of two or more bisphenol type epoxy resins.

The bisphenol-type epoxy resin contained in component (A) can be produced using various bisphenol compounds, epihalohydrin, and the like. Specific production methods include, for example, a method in which a diglycidyl ether compound obtained by reacting a bisphenol compound and epihalohydrin is further reacted with a bisphenol compound (Method 1), and a method in which a bisphenol compound and epihalohydrin are reacted directly. A method (Method 2) for obtaining the desired epoxy resin, and the like. Method 1 is preferred because the reaction is easy to control and the epoxy equivalent of the resulting epoxy resin can be easily adjusted.

As the bisphenol compound used in method 1 or 2, for example, a compound represented by the following general formula (1a) can be used. Epichlorohydrin etc. can be used as an epihalohydrin.

R ¹ and R ² in formula (1a) are the same as R ¹ and R ² in general formula (1), respectively. The compound represented by the general formula (1a) can be selected according to the type of the target bisphenol type epoxy resin [compound represented by the general formula (1)].

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

A biphenol-type epoxy resin (B) is a compound represented by the following general formula (3). Hereinafter, the "biphenol-type epoxy resin (B)" is also referred to as "(B) component".

In general formula (3), each R ⁴ is independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms. The alkyl group having 1 to 4 carbon atoms includes methyl group, ethyl group, linear or branched propyl group and linear or branched butyl group. The alkoxy group having 1 to 4 carbon atoms includes methoxy group, ethoxy group, linear or branched propoxy group and linear or branched butoxy group. ^R4 is preferably a hydrogen atom.

R ⁵ is an alkylene group having 2 to 6 carbon atoms. The alkylene group having 2 to 6 carbon atoms is specifically 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 and a hexylene group. ^R5 is preferably a linear or branched propylene group. When there is more than one ^R5 (when m is 2 or more), ^R5 may be the same or different.
m in the general formula (3) represents the number of added moles of R ⁵ O or OR ⁵ and is independently 1 or more. The two m's are respectively the number of added moles of R ⁵ O and the number of added moles of OR ⁵ per molecule of the biphenol-type epoxy resin (B) represented by the general formula (3), and may be a decimal number. Each m is preferably an integer of 1 to 7, and more preferably the sum of two m is 2 to 14.

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

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 kinds of biphenol-type epoxy resins (B) are used, the epoxy equivalent weight of the mixture of two or more kinds of biphenol-type epoxy resins should be in the range of 200 to 560, and the epoxy equivalent weight of the mixture is outside the above range. It may contain a biphenol type epoxy resin.

The biphenol-type epoxy resin (B) 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). It can be obtained by glycidyl etherification or the like.

R ⁴ in general formula (3a) is the same as R ⁴ in general formula (3). Examples of the 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 the general formula (3a)] include 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 individually by 1 type, and may be used in combination of 2 or more types. AO is preferably an alkylene oxide having 2 to 4 carbon atoms, more preferably PO.

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.

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 cured product of the curable composition containing the epoxy resin composition Excellent impact resistance can be expressed. When the ratio (Wa)/(Wb) 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 or the like together with a curing agent and/or a curing accelerator.

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

Examples of curing agents (C) and curing accelerators (D) include polyamine compounds, amide compounds, acid anhydrides, phenolic hydroxyl group-containing resins, phosphorus compounds, imidazole compounds, imidazoline compounds, urea compounds, and organic acid metal salts. , Lewis acids and amine complexes. Hereinafter, the "curing agent (C)" may be referred to as "(C) component", and the "curing accelerator (D)" may be referred to as "(D) component". Specific examples thereof include those described in Japanese Patent No. 6,721,855. An example is shown below.

Polyamine compounds include aliphatic amine compounds (such as trimethylenediamine and ethylenediamine), alicyclic and heterocyclic amine compounds (such as piperidine, piperazine, menthanediamine, isophoronediamine, methylmorpholine and ethylmorpholine). , aromatic amine compounds (eg, phenylenediamine, diaminodiphenylmethane, diaminodiphenylsulfone, benzylmethylamine, dimethylbenzylamine, m-xylenediamine, pyridine, etc.), and modified amine compounds (epoxy compound-added polyamines, etc.).
Examples of amide compounds include dicyandiamide and polyamidoamines (aliphatic dicarboxylic acids such as succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, and azelaic acid; carboxylic acid compounds such as fatty acids and dimer acids; and aliphatic polyamines and obtained by reacting with a polyamine having a polyoxyalkylene chain, etc.).
Acid anhydrides include, for example, phthalic anhydride, trimellitic anhydride, pyromellitic anhydride, maleic anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylnadic anhydride, hexahydrophthalic anhydride and methylhexahydrophthalic anhydride. acids and the like.
Phenolic hydroxyl group-containing resins include phenol novolac resins, cresol novolak resins, aromatic hydrocarbon-formaldehyde resin-modified phenol resins and dicyclopentadiene phenol addition type resins.
Phosphorus compounds include primary phosphines such as alkylphosphines such as ethylphosphine and butylphosphine, and phenylphosphine; dialkylphosphines such as dimethylphosphine and dipropylphosphine; secondary phosphines such as diphenylphosphine and methylethylphosphine; trimethylphosphine; and tertiary phosphines such as triethylphosphine and triphenylphosphine.
Examples of imidazole compounds include imidazole, methylimidazole, ethylimidazole and the like.
Examples of imidazoline compounds include 2-methylimidazoline and 2-phenylimidazoline.
Urea compounds 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, etc.).

As the curing agent (C) and curing accelerator (D), commercially available products may be used. Examples of commercially available curing agents include dicyandiamide [manufactured by Mitsubishi Chemical Corporation, "DICY7"] and aromatic dimethyl urea [manufactured by San-Apro Co., Ltd., "U-CAT 3512T"].

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.

When the curing agent (C) is used in the present invention, the amount used is preferably 0.5 to 10% by weight, more preferably 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), the epoxy resin component [(A) component, (B) component and optionally added other epoxy resin (E) ( It is preferable to use the curing agent so that the functional group in the curing agent is in the range of 0.4 to 1.0 mol per 1 mol of the epoxy group in the above.

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

The curable composition of the present invention may contain epoxy resins other than the components (A) and (B). Other epoxy resins (E) [also referred to as component (E)] include, for example, phenol novolak type, naphthol novolak type, cresol novolak type, phenol-cresol cocondensation novolak type novolac type epoxy resins, urethane-modified epoxy resins and Examples include triphenylmethane type epoxy resins.

The curable composition of the present invention may contain components other than components (A) to (E). Other ingredients include organic solvents, UV absorbers, antioxidants, silicone additives, fluorine additives, flame retardants, plasticizers, silane coupling agents, organic beads, inorganic fine particles, inorganic fillers, and rheology control agents. , defoamers, anti-fogging agents and coloring agents. These components can be added in arbitrary amounts depending on the desired performance.

The curable composition of the present invention is prepared by subjecting the (A) component, (B) component, (C) component and/or (D) component, and optionally the (E) component and the above other components to a pot mill, ball mill, , a bead mill, a roll mill, a homogenizer, a super mill, a homodisper, a universal mixer, a Banbury mixer, a kneader, and the like.

<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 method described above in a mold having a desired shape and heating at 120 to 140° C. for 1 to 3 hours. The temperature conditions, heating time, etc. in producing the cured product can be appropriately selected in consideration of the type and amount of the resin contained in the composition.

Since the cured product of the curable composition of the present invention has excellent impact resistance, it is suitable, for example, as a material for components that are expected to be used in environments subject to impact. Examples of products that are expected to be used in environments subject to impact include automobiles, drones, and nursing care robots. In addition to the above applications, the cured product of the present invention may also be used for paints, coating agents, molding materials, insulating materials, sealants, sealing agents, binding agents for fibers, and the like.

<Prepreg>
The prepreg of the present invention contains 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 the curing accelerator (D) may be used, and known epoxy resin curing agents such as those described in JP-A-2005-213337 A curing agent, a curing accelerator, and the like may also be used.

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. As the fiber sizing agent, known ones and commercially available ones can be used. Commercially available fiber sizing agents include, for example, Sanyo Chemical Industries Co., Ltd.'s "Chemitylene" series.

Fibers to be treated with a fiber sizing agent include known fibers such as glass fiber, carbon fiber, aramid fiber, ceramic fiber, metal fiber, mineral fiber, rock fiber and slag fiber (see International Publication No. 2003/47830). described, etc.) and the like. From the viewpoint of the strength of the composite material, the fibers, which are preferably carbon fibers, may be used singly or in combination of two or more.

Methods of treating fibers include spraying and dipping. The amount (% by weight) of the fiber sizing agent attached to the fibers is preferably 0.05 to 5% by weight, more preferably 0.1 to 3.0% by weight, based on the weight of the fibers. Within this range, the strength of the composite is further improved.

Textile products are textile products obtained by processing the above fiber bundles, and include woven fabrics, knitted fabrics, non-woven fabrics (felt, mat, paper, etc.), chopped fibers, milled fibers, and the like.

The prepreg of the present invention can be prepared by heat-melting the curable composition of the present invention (melting temperature: 60 to 150° C.) and impregnating it into fibers, or by using solvents (acetone, methyl ethyl ketone, methyl isobutyl ketone, toluene, xylene and ethyl acetate). etc.) to impregnate fibers with the curable composition of the present invention. When a method using a solvent is employed, it is preferable to dry the prepreg to remove the solvent.

The weight ratio of the curable composition to the fiber (curable composition/fiber) is preferably 10/90 to 90/10, more preferably 20/80 to 70/30, particularly It is preferably 30/70 to 60/40. When a catalyst is contained, the content (% by weight) of the catalyst is preferably 0.01 to 10, more preferably 0.1 to 5, and particularly preferably 0.1 to 5, relative to the curable composition, from the viewpoint of molding strength and the like. is 1-3.

<Composite material>
The composite material of the present invention is obtained by curing the prepreg of the present invention. A composite material can be obtained, for example, by thermoforming and curing the prepreg of the present invention. The curing need not be complete, but it is preferred that the composite material is cured to the extent that it can maintain its shape. The method of thermoforming is not particularly limited, and for example, a filament winding molding method (a method of winding while applying tension to a rotating mandrel and thermoforming), a press molding method (a method of laminating prepreg sheets and thermoforming), autoclave. method (a method of heat-molding a prepreg sheet by applying pressure to a mold) and a method of mixing chopped fibers or milled fibers with a matrix resin for injection molding.

EXAMPLES The present invention will be further described below with reference to Examples and Comparative Examples, but the present invention is not limited to these.

<Production Example 1: Production of PO adduct (b1) of 4,4′-dihydroxybiphenyl>
186.2 parts by weight (1 mol part) of a biphenol compound (“4,4′-dihydroxybiphenyl” [manufactured by Tokyo Kasei Kogyo Co., Ltd.]) was placed in a pressure-resistant reaction vessel equipped with a stirrer, a heating/cooling device and a dropping cylinder, 130.3 parts of methyl ethyl ketone and 1 part by weight of potassium hydroxide were added, and nitrogen substitution was performed. The temperature was raised to 110° C., and 116 parts by weight (2 mol parts) of propylene oxide was added dropwise over 19 hours while adjusting the pressure to 0.5 MPa or less, followed by aging at 110° C. for 6 hours. Thereafter, methyl ethyl ketone was distilled off under reduced pressure at 85° C. and −0.1 MPa to obtain a PO adduct (b1) of 4,4′-dihydroxybiphenyl.

<Production Example 2: Production of PO adduct (b2) of 4,4′-dihydroxybiphenyl>
PO adduct (b2) of 4,4′-dihydroxybiphenyl was prepared in the same manner as in Production Example 1, except that 116 parts by weight (2 mol parts) of PO was changed to 406 parts by weight (7 mol parts) of PO. got

<Production Example 3: Production of PO adduct (b3) of 4,4′-dihydroxybiphenyl>
PO adduct (b3) of 4,4′-dihydroxybiphenyl was prepared in the same manner as in Production Example 1, except that 116 parts by weight (2 mol parts) of PO was changed to 812 parts by weight (14 mol parts) of PO. got

<Production Example 4: Production of biphenol-type epoxy resin (B-1)>
151 parts by weight of the PO adduct (b1) of 4,4'-dihydroxybiphenyl, 278 parts by weight of epichlorohydrin and 30 parts by weight of cyclohexane were placed in a reaction vessel equipped with a stirring device, a temperature control device, and a wet pulverizer (attached to the outside of the reaction vessel). A nitrogen atmosphere (oxygen concentration: 730 ppm) was set in the reactor, and 112 parts by weight of granular potassium hydroxide in a nitrogen atmosphere at 19°C was intermittently added at 19 to 29°C over 5 hours. After that, reaction aging was performed at 25° C. to 29° C. for 5 hours to glycidyl etherify the above (b1).
Next, after cooling the inside of the tank to 16°C, 370.4 parts by weight of water at 23°C was added in the range of 20 to 28°C, stirred for 0.5 hours, and left to separate at 17°C for 0.5 hours. The (aqueous layer) was removed, and 12 parts by weight of "Kyoward 600" (manufactured by Kyowa Chemical Industry Co., Ltd.; alkali adsorbent) was added to the remaining upper layer (organic layer) and stirred at 80°C for 0.5 hour. After filtration using "Radiolite #700" (manufactured by Kyowa Chemical Industry Co., Ltd., diatomaceous earth filter aid), the temperature was raised to 110 ° C. under reduced pressure (-0.1 MPa) to distill off the epichlorohydrin and cyclohexane mixture. to obtain a biphenol type epoxy resin (B-1). The epoxy equivalent of the biphenol type epoxy resin (B-1) was measured by the method specified in JIS K7236.

<Production Example 5: Production of biphenol-type epoxy resin (B-2)>
In Production Example 4, 296 parts by weight of the PO adduct of 4,4′-dihydroxybiphenyl (b-2) was used in place of 151 parts by weight of the PO adduct of 4,4′-dihydroxybiphenyl (b-1). A biphenol type epoxy resin (B-2) was obtained by performing the same operation as in Production Example 4 except for the above. The epoxy equivalent of the biphenol-type epoxy resin (B-2) was measured in the same manner as in (B-1) above.

<Production Example 6: Production of biphenol-type epoxy resin (B-3)>
In Production Example 4, 499 parts by weight of the PO adduct of 4,4′-dihydroxybiphenyl (b-3) was used in place of 151 parts by weight of the PO adduct of 4,4′-dihydroxybiphenyl (b-1). A biphenol type epoxy resin (B-3) was obtained by performing the same operation as in Production Example 4 except for the above. The epoxy equivalent of the biphenol-type epoxy resin (B-3) was measured in the same manner as in (B-1) above.

<Examples 1 to 5 and Comparative Examples 1 to 2>
(Preparation of curable composition)
Bisphenol type epoxy resins (A-1), (A-2), (A-3), biphenol type epoxy resins (B-1) to (B-3) or ( B'-1), the curing agent (C-1) and the curing accelerator (D-1) are mixed at 1400 rpm and 100°C for 3 minutes using a stirring deaerator (manufactured by THINKY, ARV-930TWIN), A curable composition was obtained.

Components used in 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 column "epoxy equivalent of component (A)" and the column "epoxy equivalent of component (B)" describe the epoxy equivalent of the compound when one type of compound is used, and two or more types of epoxy equivalents. When using a compound, the epoxy equivalent of a mixture of two or more compounds is described. In the column of "epoxy equivalent of epoxy resin composition" in Table 1, the epoxy equivalent of the mixture of component (A) and component (B) is described. The epoxy equivalent weight of the mixture was calculated using formula (X) above.
(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 obtained in Production Example 1 (2 moles of PO added) (epoxy equivalent: 207.1)
(B-2): Biphenol-type epoxy resin obtained in Production Example 2 (10 moles of PO added) (epoxy equivalent: 352.2)
(B-3): Biphenol-type epoxy resin obtained in Production Example 3 (14 moles of PO added) (epoxy equivalent: 555.6)
(C-1): Dicyandiamide ["DICY7" manufactured by Mitsubishi Chemical Corporation]
(D-1): Aromatic dimethyl urea ["U-CAT 3512T" manufactured by San-Apro Co., Ltd.]

(Preparation and evaluation of cured product)
The curable compositions of Examples 1 to 5 and Comparative Examples 1 and 2 were placed in a mold for preparing a test piece (notched test piece) having a size specified in JIS K7110 (ISO180) and heated at 130°C for 1 hour. By heating for a period of time, a sheet-like cured product having a thickness of 4 mm, a length of 80 mm and a width of 10 mm was obtained. The cured product was used as a test piece. Using the test piece, it was evaluated by the following performance test. Table 1 shows the results.

<Performance test: Evaluation of impact resistance of cured product>
An Izod impact test was performed according to the method specified in JIS K-7110 to measure the impact strength (unit: kJ/m ² ). The larger the value, the better the impact resistance.

<Performance test: evaluation of impact resistance of composite materials>
(Production of prepreg)
The curable compositions of Examples 1 to 5 and Comparative Examples 1 and 2 were applied onto release paper using a knife coater to prepare two resin films. Carbon fibers treated with a sizing agent [fineness of 800 tex, number of filaments of 12,000, "chemitylene FS-6" as a sizing agent, manufactured by Sanyo Chemical Industries Co., Ltd.] are arranged in a sheet in one direction. made. Next, one sheet of the resin film is placed on each side of the carbon fiber treated with a sizing agent, and the thermosetting resin composition is impregnated in one direction by pressurizing and heating at a temperature of 85° C. and a pressure of 2 MPa. Got the prepreg.

(Evaluation of impact resistance)
The Charpy impact value of the (fiber-reinforced) composite material was measured by the following method.
A laminate was prepared by laminating so that the fiber direction of the unidirectional prepreg was the same and the thickness (laminate) was about 3 mm. It was cured under heat and pressure for 2 hours to produce a unidirectional fiber reinforced composite material.
A test piece having a thickness of 3±0.2 mm, a width of 10±0.2 mm, and a length of 80 mm was cut from the obtained fiber-reinforced composite material of each example. Using the test piece, according to the method specified in JIS K7077 (1991), a Charpy impact test (without notch) was performed by applying a flatwise impact with a weighing weight of 300 kg cm, and the impact value (unit: kJ / m ² ) was measured. It was measured. The number of measurements was n=5 and the average value was calculated. Table 1 shows the results. The larger the value, the better the impact resistance.

As shown in Table 1, a component (A) containing a bisphenol type epoxy resin represented by the general formula (1) and having an epoxy equivalent in the range of 180 to 700, and a general epoxy equivalent having an epoxy equivalent in the range of 200 to 560 and a biphenol type epoxy resin (B) represented by the formula (3), and a weight ratio (Wa)/(Wb) of 72/28 to 85/15. As for the cured product, a result was obtained that the impact resistance was superior to that of the comparative example. Also, the composite material of the example was superior to the comparative example in the impact test results. From these results, it was found that the present invention can provide an epoxy resin composition that imparts excellent impact resistance to the cured product.

Claims (11)

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 the following general formula (3) having an epoxy equivalent in the range of 200 to 560 and a biphenol-type epoxy resin (B) represented,
An epoxy resin composition wherein 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.

[wherein each R ¹ is 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 represents the following general formulas (2-1) to (2- 7), n is the number of moles of the group represented by the following general formula (2A), and is 0.1 or more. ]

[In the formula, each R ³ is independently either an alkyl group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms. ]

[In the formula, each R ¹ is 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 represents the above general formulas (2-1) to (2- 7) is a structural moiety represented by any one of ]

[In the formula, R ⁴ is 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, m represents the number of added moles of R ⁵ O or OR ⁵ and is each independently a number of 1 or more. ] 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 two m is 2 to 14. 3. The epoxy resin composition according to claim 1, wherein the epoxy equivalent of the epoxy resin composition is in the range of 250-600. A curable composition comprising the epoxy resin composition according to claim 1 or 2, and a curing agent and/or curing accelerator. 5. The curable composition of claim 4, wherein said curing agent comprises dicyandiamide. A cured product obtained by curing the curable composition according to claim 4 . A cured product obtained by curing the curable composition according to claim 5 . A prepreg comprising the curable composition according to claim 4 and reinforcing fibers. A prepreg comprising the curable composition according to claim 5 and reinforcing fibers. A composite material obtained by curing the prepreg according to claim 8 . A composite material obtained by curing the prepreg according to claim 9 .