Composition, kit, and cured product

Abstract

Provided is a composition or the like which comprises epoxy resins and a curing agent, and in which the epoxy resins include a tetrafunctional epoxy resin, the content of the tetrafunctional epoxy resin is 10-100 parts by mass with respect to 100 parts by mass of the epoxy resins, and the curing agent includes a curing agent represented by general formula (A). In the formula , R1-R4 each independently represent an alkyl group having 1-4 carbon atoms, R5 represents an alkyl group having 1-16 carbon atoms, and n represents an integer of 0-4.

Description

Compositions, kits, and cured products

[0001] The present invention relates to compositions, kits, and cured products. This application claims priority under Japanese Patent Application No. 2025-006966, filed in Japan on January 17, 2025, the contents of which are incorporated herein by reference.

[0002] In recent years, epoxy resin cured products have been found in applications such as automotive parts and aircraft parts. When epoxy resin compositions are used in the above applications, the cured products obtained by curing the epoxy resin composition are required to have a high glass transition temperature and a high elastic modulus even at high temperatures.

[0003] Non-patent document 1 describes a study on the effect of steric hindrance by amines on the physical properties of cured products when amines are used as curing agents for bisphenol A type diglycidyl ether. In this document, m-xylylenediamine used as a curing agent is compared with an unsubstituted version and a version in which the hydrogen atom bonded to the carbon atom adjacent to the amino group is substituted with a methyl group. According to this document, the epoxy resin cured product using the latter had a higher glass transition temperature than the epoxy resin cured product using the former.

[0004] Non-patent document 2 describes a study on the effect of steric hindrance of amines on the physical properties of cured products when aliphatic amines and aromatic amines are used as curing agents for bisphenol A type diglycidyl ether. According to this document, hindered amine epoxy cured products showed higher glass transition temperatures and rubber moduli compared to non-hindered amine epoxy cured products.

[0005] The effects of steric hindrance on sub-glass transitions in epoxy polymers, POLYMER, 1992, vol 33 (10), 2114.

[0006] THE EFFECTS OF STERIC HINDRANCE ON PHYSICAL PROPERTIES IN AMINE-CURED EPOXIES, Journal of Applied Polymer Science, 1988, vol 35(5), 1367.

[0007] The cured products of amines and bisphenol A type diglycidyl ethers disclosed in Non-Patent Documents 1 and 2 have insufficient glass transition temperatures and high-temperature moduli, and improvements are needed.

[0008] The present disclosure aims to provide a composition capable of producing a cured product with a high glass transition temperature and a high high-temperature modulus, a kit for obtaining the composition, and a cured product obtained by curing the composition.

[0009] As a result of diligent research to solve the above problems, the present inventors have found that by using a specific combination of epoxy resin and curing agent, it is possible to obtain a cured product with a high glass transition temperature and high elastic modulus at high temperatures, and have completed this disclosure.

[0010] To address the above issues, this disclosure includes the following aspects.

[0011] [1] A composition comprising an epoxy resin and a curing agent, wherein the epoxy resin comprises a tetrafunctional epoxy resin, the content of which is 10 to 100 parts by mass per 100 parts by mass of the epoxy resin, and the curing agent comprises a curing agent represented by the following general formula (A).

[0012] [In the formula, R １ ~R ４ Each of these independently represents an alkyl group having 1 to 4 carbon atoms. ５ [where n is an integer between 0 and 4]

[0013] [2] The composition according to [1], wherein the content of the tetrafunctional epoxy resin is 10 to 90 parts by mass per 100 parts by mass of the epoxy resin.

[0014] [3] The composition according to [1] or [2], wherein the tetrafunctional epoxy resin comprises a tetrafunctional epoxy compound represented by the following chemical formula (B-1).

[0015]

[0016] [4] The composition according to any one of [1] to [3], wherein the epoxy resin comprises the tetrafunctional epoxy resin and the bifunctional epoxy resin.

[0017] [5] The composition according to [4], wherein the bifunctional epoxy resin is a bisphenol-type epoxy resin.

[0018] [6] A kit comprising a first liquid containing an epoxy resin and a second liquid containing a curing agent represented by the following general formula (A), wherein the epoxy resin contains 10 to 100 parts by mass of a tetrafunctional epoxy resin per 100 parts by mass of the epoxy resin.

[0019] [In the formula, R １ ~R ４ Each of these independently represents an alkyl group having 1 to 4 carbon atoms. ５ [where n is an integer between 0 and 4]

[0020] [7] A cured product obtained by curing any one of the compositions described in [1] to [5].

[0021] [8] A cured product obtained by curing a composition obtained by mixing the first liquid and the second liquid of the kit described in [6].

[0022] According to this disclosure, it is possible to provide a composition capable of producing a cured product with a high glass transition temperature and a high high-temperature modulus, a kit for obtaining the composition, and a cured product.

[0023] This figure shows the storage modulus (G') [GPa] and loss tangent (tanδ) of the cured product obtained by curing the composition of Example 4.

[0024] The embodiments of this disclosure will be described in detail below.

[0025] In the present disclosure, when a numerical range is described as, for example, "1 to 10 parts by mass", it means a range from 1 part by mass to 10 parts by mass, and means a numerical range including the lower limit value of 1 part by mass and the upper limit value of 10 parts by mass.

[0026] (Composition) One embodiment of the composition according to the present disclosure contains an epoxy resin and a curing agent represented by the general formula (A).

[0027] <Epoxy Resin> The epoxy resin in the present disclosure is an epoxy group-containing compound having an epoxy group in the molecule (hereinafter also referred to as "epoxy compound"). The epoxy equivalent of the epoxy resin in the present disclosure is preferably 30 to 1000 g / eq, more preferably 30 to 500 g / eq, still more preferably 50 to 300 g / eq, and particularly preferably 50 to 250 g / eq. The epoxy equivalent of the epoxy resin can be measured according to JIS K 7236. The upper limit value and the lower limit value of the above range can be arbitrarily combined.

[0028] <<Tetrafunctional Epoxy Resin>> One embodiment of the composition according to the present disclosure contains a tetrafunctional epoxy resin as the epoxy resin. In the present disclosure, the "tetrafunctional epoxy resin" is a monomer of an epoxy compound having four epoxy groups (hereinafter also referred to as "tetrafunctional epoxy compound"). "Tetrafunctional" means that the epoxy compound has four epoxy groups per molecule.

[0029] The tetrafunctional epoxy resin may contain an aromatic amine type epoxy resin and may contain a tetrafunctional epoxy compound represented by the following chemical formula (B-1).

[0030]

[0031] The content of the tetrafunctional epoxy compound represented by the chemical formula (B-1) may be 95 to 100 parts by mass, preferably 98 to 100 parts by mass, more preferably 99 to 100 parts by mass, and still more preferably 100 parts by mass with respect to 100 parts by mass of the tetrafunctional epoxy resin. The upper limit value and the lower limit value of the above range can be arbitrarily combined.

[0032] The tetrafunctional epoxy resin may be used alone or in combination of two or more. From the viewpoint of obtaining a cured product having a high glass transition temperature and a high high-temperature elastic modulus, the content of the tetrafunctional epoxy resin in the composition of the present disclosure is preferably 10 parts by mass or more, more preferably 25 parts by mass or more, per 100 parts by mass of the epoxy resin. Further, from the viewpoint of obtaining a cured product having a low water absorption rate, the content of the tetrafunctional epoxy resin in the composition of the present disclosure is preferably 100 parts by mass or less, more preferably 90 parts by mass or less, still more preferably 75 parts by mass or less, particularly preferably 50 parts by mass or less, per 100 parts by mass of the epoxy resin. The upper limit value and the lower limit value of the above range can be arbitrarily combined. The content of the tetrafunctional epoxy resin in the composition of the present disclosure may be, for example, 10 to 100 parts by mass, 10 to 90 parts by mass, 10 to 75 parts by mass, 10 to 50 parts by mass, or 25 to 50 parts by mass per 100 parts by mass of the epoxy resin. The upper limit value and the lower limit value of the above range can be arbitrarily combined.

[0033] <<Difunctional Epoxy Resin>> One embodiment of the composition according to the present disclosure may contain a tetrafunctional epoxy resin and a difunctional epoxy resin as the epoxy resin. In the present disclosure, "difunctional" means that the epoxy compound has two epoxy groups per molecule. Examples of the difunctional epoxy resin include bisphenol type epoxy resins, aliphatic diol diglycidyl ethers derived from aliphatic diols, (poly)alkylene glycol diglycidyl ethers, and the like. The difunctional epoxy resin may include a bisphenol type epoxy resin represented by the following general formula (B-2).

[0034] [In the formula, X is an alkylene group having 1 to 4 carbon atoms, -SO ２ - or a divalent group formed by bonding these. m is an integer of 0 or more. ]

[0035] In the general formula (B-2), X may be -CH ２ -, -C(CH ３ ) ２ ​​- may be, especially -C(CH ３ ) ２ - is preferred. In the above general formula (B-2), m may be 0, 1, 2, or 3.

[0036] The content of the bisphenol-type epoxy resin represented by the general formula (B-2) in the composition of the present disclosure may be 95 to 100 parts by mass or more, preferably 98 to 100 parts by mass, more preferably 99 to 100 parts by mass, and even more preferably 100 parts by mass, per 100 parts by mass of the bifunctional epoxy resin. The upper and lower limits of the above range can be any combination.

[0037] The bifunctional epoxy resin may be used alone or in combination of two or more types. The content of the bifunctional epoxy resin in the composition of this disclosure may be 0 to 90 parts by mass, preferably 10 to 90 parts by mass, more preferably 25 to 90 parts by mass, even more preferably 50 to 90 parts by mass, and particularly preferably 50 to 75 parts by mass, per 100 parts by mass of epoxy resin. The upper and lower limits of the above range can be arbitrarily combined.

[0038] The content of the difunctional epoxy resin in the composition of this disclosure may be 0 to 90 parts by mass, preferably 10 to 90 parts by mass, more preferably 25 to 90 parts by mass, even more preferably 50 to 90 parts by mass, and particularly preferably 50 to 75 parts by mass, based on 100 parts by mass of the total of the tetrafunctional epoxy resin and the difunctional epoxy resin. The upper and lower limits of the above range can be any combination.

[0039] From the viewpoint of obtaining a cured product with a high glass transition temperature, the content of the tetrafunctional epoxy resin in the composition of this disclosure is preferably 10 parts by mass or more, more preferably 25 parts by mass or more, based on 100 parts by mass of the total of the tetrafunctional epoxy resin and the difunctional epoxy resin. From the viewpoint of obtaining a cured product with a low water absorption rate, the content of the tetrafunctional epoxy resin in the composition of this disclosure is preferably 100 parts by mass or less, more preferably 90 parts by mass or less, even more preferably 75 parts by mass or less, and particularly preferably 50 parts by mass or less, based on 100 parts by mass of the total of the tetrafunctional epoxy resin and the difunctional epoxy resin. The upper and lower limits of the above range can be arbitrarily combined. For example, the content of the tetrafunctional epoxy resin in the composition of this disclosure may be 10 to 100 parts by mass, preferably 10 to 90 parts by mass, more preferably 10 to 75 parts by mass, even more preferably 10 to 50 parts by mass, and particularly preferably 25 to 50 parts by mass, based on 100 parts by mass of the total mass of the tetrafunctional epoxy resin and the difunctional epoxy resin. The upper and lower limits of the aforementioned range can be combined in any way.

[0040] The total content of the tetrafunctional epoxy resin and the bifunctional epoxy resin may be 30 to 100 parts by mass, preferably 50 to 100 parts by mass, more preferably 70 to 100 parts by mass, and even more preferably 90 to 100 parts by mass, per 100 parts by mass of epoxy resin, from the viewpoint of obtaining a cured product with a high glass transition temperature and a high high-temperature modulus.

[0041] <<Other Epoxy Resins>> The compositions relating to this disclosure may also include epoxy resins other than the tetrafunctional epoxy resin and the difunctional epoxy resin described above (other epoxy resins). Examples of other epoxy resins include polyfunctional epoxy resins (excluding the tetrafunctional epoxy resin) containing epoxy group-containing compounds having three or more epoxy groups in their molecule. Examples of polyfunctional epoxy resins include polyol-type epoxy resins derived from polyols, cresol novolac-type epoxy resins, phenol novolac-type epoxy resins, naphthalene-type epoxy resins, aromatic aminophenol-type epoxy resins, and the like. The above polyfunctional epoxy resins may be used individually or in combination of two or more.

[0042] The epoxy resin content in the composition according to this disclosure may be 10 or more but less than 100 parts by mass, 30 to 95 parts by mass, 35 to 95 parts by mass, 40 to 90 parts by mass, 50 to 90 parts by mass, 50 to 86 parts by mass, or 50 to 84 parts by mass per 100 parts by mass of the composition. The upper and lower limits of the above range can be any combination.

[0043] The total content of the tetrafunctional epoxy resin and the bifunctional epoxy resin in the composition according to this disclosure may be 10 or more but less than 100 parts by mass, 30 to 95 parts by mass, 35 to 95 parts by mass, 40 to 90 parts by mass, 50 to 90 parts by mass, 50 to 86 parts by mass, or 50 to 84 parts by mass per 100 parts by mass of the composition. The upper and lower limits of the above range can be any combination.

[0044] The content of the tetrafunctional epoxy resin in the composition according to this disclosure may be 10 parts by mass or more but less than 100 parts by mass, 30 to 95 parts by mass, 35 to 95 parts by mass, 40 to 90 parts by mass, 50 to 90 parts by mass, 50 to 86 parts by mass, or 50 to 84 parts by mass per 100 parts by mass of the composition. The upper and lower limits of the above range can be any combination.

[0045] The composition according to this disclosure may contain the bifunctional epoxy resin in an amount of 0 to 95 parts by mass, 30 to 95 parts by mass, 35 to 95 parts by mass, 40 to 90 parts by mass, 50 to 90 parts by mass, 50 to 86 parts by mass, or 50 to 84 parts by mass per 100 parts by mass of the composition. The upper and lower limits of the above range can be combined arbitrarily.

[0046] <Curing Agent> The composition according to this disclosure includes a curing agent. The curing agent includes a curing agent represented by the following general formula (A). The curing agent represented by the following general formula (A) reacts with the epoxy resin and has the effect of curing the composition.

[0047] [In the formula, R １ ~R ４ Each of these independently represents an alkyl group having 1 to 4 carbon atoms. ５ [where n is an integer between 0 and 4]

[0048] The aforementioned R １ ~R ４ The alkyl groups may be linear or branched, independently of each other. １ ~R ４ Examples of alkyl groups include, independently, methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, isobutyl, and tert-butyl groups. Among these, the R １ ~R ４ The alkyl group may be a methyl group.

[0049] The aforementioned R ５ The alkyl group in R may be linear, cyclic, or a combination thereof. ５ The linear alkyl group in R may be linear or branched. ５ The linear alkyl group in R is １ ~R ４ In addition to the alkyl groups listed above, other examples include pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group and their isomers. ５ The alkyl group in the cyclic structure may be monocyclic or polycyclic. ５ Examples of monocyclic alkyl groups in this context include cycloalkanes such as cycloheptyl and cyclohexyl groups, which have one hydrogen atom removed. ５ Examples of polycyclic alkyl groups in this context include decalin, adamantane, and other groups obtained by removing one hydrogen atom. When n is an integer of 2 or more, each R ５ They may be the same or they may be different.

[0050] The content of the curing agent represented by the general formula (A) in the composition of the present disclosure may be 70 to 100 parts by mass, 80 to 100 parts by mass, 90 to 100 parts by mass, 100 parts by mass, and preferably 100 parts by mass, per 100 parts by mass of the curing agent. The upper and lower limits of the above range can be any combination.

[0051] The curing agent content in the composition of this disclosure is set so that the total amount of active hydrogen from the amino groups of the curing agent is 0.8 to 1.1 mol, preferably 0.9 to 1.05 mol, and more preferably 0.95 to 1.0 mol, per 1 mol of epoxy groups of the epoxy resin. The upper and lower limits of the above range can be arbitrarily combined. When the curing agent content in the composition of this disclosure is within the above range, the resulting cured product has a high glass transition temperature, a high high-temperature modulus, and a low water absorption rate.

[0052] <<Other Curing Agents>> In addition to the curing agent represented by the general formula (A) above, the composition according to this disclosure may also contain other curing agents. Examples of other curing agents include aliphatic amines and aromatic amines (excluding the curing agent represented by the general formula (A) above). Examples of the aliphatic amines include ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, 1,3-diaminopropane, iminobispropylamine, 1,4-diaminobutane, hexamethylenediamine, bis(hexamethylene)triamine, 2-methylpentamethylenediamine, trimethylhexamethylenediamine, N-hydroxyethylethylenediamine, isophoronediamine, menthanediamine, N-aminoethylpiperazine, bis(4-amino-3-methyldicyclohexyl)methane, bis(aminomethyl)cyclohexane, 3,9-bis(3-aminopropyl)-2,4,8,10-tetraoxaspiro(5,5)undecane, norbornenediamine, m-xylylenediamine, and p-xylylenediamine. Examples of the aforementioned aromatic amines include m-phenylenediamine, o-phenylenediamine, p-phenylenediamine, 2,4-diaminoanisole, 2,4-toluenediamine, 2,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylmethane, 4,4'-ethylenedianiline, 3,3'-diaminodiphenylsulfone, 4,4'-diaminodiphenylsulfone, bis(4-amino-3-ethyl-5-methylphenyl)methane, α,α'-bis(4-aminophenyl)-m-diisopropylbenzene, and α,α'-bis(4-aminophenyl)-p-diisopropylbenzene.

[0053] Other curing agents may be used individually or in combination of two or more. The content of the other curing agents may be 0 to 30 parts by mass, 0 to 20 parts by mass, 0 to 10 parts by mass, or 0 parts by mass, preferably 0 parts by mass, based on 100 parts by mass of the total of the curing agent represented by the general formula (A) and the other curing agents. The upper and lower limits of the above range can be combined arbitrarily.

[0054] The content of the curing agent represented by the general formula (A) may be 70 to 100 parts by mass, 80 to 100 parts by mass, 90 to 100 parts by mass, or 100 parts by mass, preferably 100 parts by mass, based on 100 parts by mass of the total of the curing agent represented by the general formula (A) and the other curing agents. The upper and lower limits of the above range can be any combination.

[0055] The curing agent content is set so that, per 1 mol of epoxy groups in the epoxy resin, the total of the active hydrogen of the amino groups of the curing agent represented by general formula (A) and the active hydrogen of the amino groups of the other curing agents is in the range of 0.8 to 1.1 mol, preferably 0.9 to 1.05 mol, and more preferably 0.95 to 1.0 mol. The upper and lower limits of the above range can be arbitrarily combined.

[0056] <Other Components> The compositions relating to this disclosure may further contain other components such as inorganic fillers, colorants, stress relievers, coupling agents, thixotropes, and other flow-modifying components, as well as defoamers and flame retardants, to the extent that they do not impair the effects of this disclosure.

[0057] <<Inorganic Fillers>> Inorganic fillers are not particularly limited, but examples include inorganic oxides such as fused silica, crystalline silica, aluminum oxide, zirconium oxide, titanium oxide, zinc oxide, iron oxide, copper oxide, tin oxide, cerium oxide, tantalum oxide, niobium oxide, tungsten oxide, europium oxide, yttrium oxide, molybdenum oxide, indium oxide, antimony oxide, germanium oxide, lead oxide, bismuth oxide, and hafnium oxide; salt particles such as calcium silicate, calcium carbonate, magnesium carbonate, and potassium titanate; inorganic carbide particles such as silicon carbide; inorganic nitride particles such as aluminum nitride and boron nitride; and metal particles such as nickel, magnesium, and tungsten. By including inorganic fillers, the mechanical properties of the resulting cured product can be improved, and the fluidity of the composition can be adjusted.

[0058] <<Coloring agents>> Examples of coloring agents include carbon black and pigments.

[0059] <<Stress Relief Agents>> Examples of stress relief agents include silicone resins, butyl acrylate resins, polyetheramine resins, elastomer particles, thermoplastic resins, functionally modified thermoplastic resins, rubber resins, and functionally modified rubber resins.

[0060] <<Other Additives>> Conventionally known additives can be used as flow-adjusting components such as coupling agents and thixotropes, as well as defoaming agents, flame retardants, etc.

[0061] As described above, the composition of this embodiment comprises an epoxy resin containing a tetrafunctional epoxy resin and a curing agent represented by the general formula (A). The cured product of the composition of this embodiment has a high glass transition temperature and a high high-temperature modulus. Generally, as the crosslinking density of the cured product increases and the glass transition temperature increases, the water absorption rate also increases. On the other hand, the cured product of the composition of this embodiment has a high glass transition temperature and a low water absorption rate.

[0062] (Kit) The kit of this embodiment comprises a first liquid containing an epoxy resin and a second liquid containing a curing agent represented by the following general formula (A), wherein the epoxy resin contains 10 to 100 parts by mass of a tetrafunctional epoxy resin per 100 parts by mass of the epoxy resin.

[0063] [In the formula, R １ ~R ４ Each of these independently represents an alkyl group having 1 to 4 carbon atoms. ５ [where n is an integer between 0 and 4]

[0064] The tetrafunctional epoxy resin contained in the first liquid of the kit of this embodiment is the same as the tetrafunctional epoxy resin in the composition described above. The curing agent represented by general formula (A) contained in the second liquid of the kit of this embodiment is the same as the curing agent represented by general formula (A) in the composition described above.

[0065] The mixing ratio of the first liquid and the second liquid is set such that the total amount of active hydrogen from the amino groups of the curing agent contained in the second liquid is in the range of 0.8 to 1.1 mol, preferably 0.9 to 1.05 mol, and more preferably 0.95 to 1.0 mol, relative to 1 mol of epoxy groups contained in the epoxy resin in the first liquid. When the mixing ratio of the first liquid and the second liquid is within the above range, the resulting cured product has a high glass transition temperature, a high high-temperature modulus, and a low water absorption rate.

[0066] According to the kit of this embodiment, the composition of the embodiment described above can be obtained. The cured product of this composition has a high glass transition temperature and a high high-temperature modulus. Generally, when the crosslinking density of a cured product increases and the glass transition temperature increases, the water absorption rate also increases. On the other hand, according to the kit of this embodiment, the glass transition temperature of the resulting cured product is high and the water absorption rate is kept low.

[0067] (Cured product) One embodiment of the cured product according to this disclosure is a cured product obtained by curing the composition of the above-described embodiment or the composition obtained by the kit of the above-described embodiment. There is no particular provision for the method of producing the cured product. From a process viewpoint, it is preferably produced by heating.

[0068] [Measurement of the glass transition temperature of the cured material] In this embodiment, the glass transition temperature of the cured material can be the temperature of the peak top of the loss tangent (tanδ) obtained from the results of dynamic viscoelasticity measurement of the cured material test piece.

[0069] <Preparation of Cured Product> The composition of the above embodiment is poured into a SUS mold (1 mm thick) and degassed at 60°C for 0.5 hours. The composition is then cured to obtain a sheet-like cured product. The curing conditions are such that no exothermic reaction is observed when each cured product is measured by DSC.

[0070] <Preparation of Test Specimens> The 1 mm thick sheet-like cured material obtained in <Preparation of Cured Material> above is cut into pieces measuring 10 mm in width and 25 mm in length to form test specimens. The dynamic viscoelasticity of the test specimens is measured under the following dynamic viscoelasticity measurement conditions. The temperature at the peak top of the obtained tanδ is defined as the glass transition temperature (Tg (°C)). A higher glass transition temperature indicates superior heat resistance.

[0071] <Dynamic Viscoelasticity Measurement Conditions> Dynamic viscoelasticity measuring device: MCR301 (manufactured by Anton Paar) Strain: 0.01% Frequency: 1 Hz Measurement temperature: 40°C to 300°C Heating rate: 5°C / min

[0072] The dynamic viscoelasticity measuring device described above is just one example; other measuring devices may be used as long as they can perform similar measurements without affecting the measurement results.

[0073] [Measurement of the temperature at which the elastic modulus of the cured material reaches 1 GPa] The elastic modulus of the cured material at high temperatures can be evaluated by the temperature at which the storage modulus (G') of the cured material decreases to 1 GPa, obtained by the dynamic viscoelasticity measurement described above. The higher the temperature at which the storage modulus (G') of the cured material decreases to 1 GPa, the higher the strength of the cured material at high temperatures.

[0074] [Measurement of Water Absorption Rate of Cured Material] The test specimen prepared in the above <Preparation of Test Specimen> is vacuum dried at 100°C for 2 hours. The mass of the test specimen after vacuum drying is measured. Next, the test specimen is allowed to absorb water under the following water absorption conditions, and the mass of the test specimen after water absorption is measured. The water absorption rate (%) is calculated from the change in mass before and after water absorption.

[0075] <Water Absorption Measurement Conditions> Water absorption device: EHS-222 (manufactured by ESPEC) Temperature: 120°C Relative humidity: 100%RH Water absorption time: 62 hours

[0076] The water absorption device described above is just one example; other measuring devices may be used as long as they allow for similar measurements and do not affect the measurement results.

[0077] The cured product of this embodiment has a high glass transition temperature and high high-temperature modulus because it is a cured product of the composition described above. Generally, when the crosslinking density of a cured product increases and the glass transition temperature increases, the water absorption rate also increases. On the other hand, the cured product of this embodiment has a high glass transition temperature and a low water absorption rate.

[0078] The present disclosure will be explained below with reference to examples, but the present disclosure is not limited to the following examples.

[0079] <Synthesis of the curing agent> 1,3-bis(2-isocyanato-2-propyl)benzene (120 g) was added to 19% hydrochloric acid (1000 g) to prepare a reaction solution. The prepared reaction solution was stirred at 85°C for 6.5 hours, and then air-cooled to about 25°C. Sodium hydroxide aqueous solution was added to the reaction solution to adjust the pH to 12. The pH-adjusted reaction solution was separated with chloroform, and the target product was extracted into chloroform. The chloroform solution was concentrated under reduced pressure. The solution after reduced pressure concentration was purified by distillation to obtain α,α,α',α'-tetramethyl-m-xylylenediamine (TMMXDA).

[0080] <Preparation of Composition> The curing agent TMMXDA synthesized in <Synthesis of Curing Agent> above and the epoxy resin were mixed in the mass ratio shown in Table 1 to prepare the composition. The epoxy resins used are as follows: (a) SumiEpoxy® ELM-434VL (N,N,N',N'-tetrakis(oxiran-2-ylmethyl)-4,4'-methylenedianiline, manufactured by Sumitomo Chemical Co., Ltd., epoxy equivalent 115 g / eq) (b) Adeka Resin® EP-4300E (bisphenol A type epoxy resin, ADEKA Corporation, epoxy equivalent 185 g / eq)

[0081]

[0082] [Measurement of the glass transition temperature of the cured material] The glass transition temperature of the cured material in this embodiment was determined from the results of dynamic viscoelasticity measurements of the cured material test specimen.

[0083] <Preparation of Cured Products> The composition prepared in the above [Preparation of Composition] was poured into a SUS mold (1 mm thick) and degassed at 60°C for 0.5 hours. Then, it was cured under the conditions shown in Table 2 to obtain a sheet-like cured product. The curing conditions were determined by DSC measurement of each cured product to ensure that no exothermic reaction was observed.

[0084]

[0085] <Preparation of Test Specimens> The 1 mm thick sheet-like cured material obtained in <Preparation of Cured Material> above was cut into pieces measuring 10 mm in width and 25 mm in length to form test specimens. The dynamic viscoelasticity of the test specimens was measured under the dynamic viscoelasticity measurement conditions described below. The temperature of the peak top of the obtained tanδ was defined as the glass transition temperature (Tg (°C)) and is shown in Table 3.

[0086] <Dynamic Viscoelasticity Measurement Conditions> Dynamic viscoelasticity measuring device: MCR301 (manufactured by Anton Paar) Strain: 0.01% Frequency: 1 Hz Measurement temperature: 40°C to 300°C Heating rate: 5°C / min

[0087] [Measurement of the temperature at which the elastic modulus of the cured material is 1 GPa] The elastic modulus of the cured material at high temperatures was evaluated using the temperature at which the storage modulus (G') of the cured material decreases to 1 GPa, obtained by the dynamic viscoelasticity measurement described above. The temperatures (°C) at which the storage modulus (G') of the cured material is 1 GPa are shown in Table 3.

[0088] [Measurement of Water Absorption Rate of Cured Material] The water absorption rate of the cured material was measured by the following method. The test specimens prepared in the above [Measurement of Glass Transition Temperature] were vacuum-dried at 100°C for 2 hours. The mass of the test specimens after vacuum drying was measured. Next, the test specimens were allowed to absorb water under the following water absorption conditions, and the mass of the test specimens after water absorption was measured. The water absorption rate (%) was calculated from the change in mass before and after water absorption. The calculated water absorption rates (%) are shown in Table 3.

[0089] <Water Absorption Measurement Conditions> Water absorption device: EHS-222 (manufactured by ESPEC) Temperature: 120°C Relative humidity: 100%RH Water absorption time: 62 hours

[0090] The cured products obtained by curing the compositions of Examples 1 to 4 were found to have a higher glass transition temperature and a higher temperature at which the elastic modulus decreased to 1 GPa compared to the composition of Comparative Example 1. Furthermore, despite the high glass transition temperature, the cured products obtained by curing the compositions of Examples 1 to 4 were found to have a low water absorption rate.

[0091] While preferred embodiments of the present invention have been described above, the present invention is not limited to these embodiments. Additions, omissions, substitutions, and other modifications are possible without departing from the spirit of the invention. The present invention is not limited by the foregoing description, but only by the scope of the appended claims.

[0092] The present invention provides a composition capable of producing a cured product having a high glass transition temperature and a high high-temperature modulus, a kit for obtaining the composition, and a cured product obtained by curing the composition.

Claims

1. A composition comprising an epoxy resin and a curing agent, wherein the epoxy resin comprises a tetrafunctional epoxy resin, the content of the tetrafunctional epoxy resin is 10 to 100 parts by mass per 100 parts by mass of the epoxy resin, and the curing agent comprises a curing agent represented by the following general formula (A). [In the formula, R １ ~R ４ Each of these independently represents an alkyl group having 1 to 4 carbon atoms. ５ [where n is an integer between 0 and 4] 2. The composition according to claim 1, wherein the content of the tetrafunctional epoxy resin is 10 to 90 parts by mass per 100 parts by mass of the epoxy resin.

3. The composition according to claim 1, wherein the tetrafunctional epoxy resin comprises a tetrafunctional epoxy compound represented by the following chemical formula (B-1).

4. The composition according to claim 1, wherein the epoxy resin comprises the tetrafunctional epoxy resin and the bifunctional epoxy resin.

5. The composition according to claim 4, wherein the bifunctional epoxy resin is a bisphenol-type epoxy resin.

6. A kit comprising a first liquid containing an epoxy resin and a second liquid containing a curing agent represented by the following general formula (A), wherein the epoxy resin contains 10 to 100 parts by mass of a tetrafunctional epoxy resin per 100 parts by mass of the epoxy resin. [In the formula, R １ ~R ４ Each of these independently represents an alkyl group having 1 to 4 carbon atoms. ５ [where n is an integer between 0 and 4] 7. A cured product obtained by curing the composition described in claim 1.

8. A cured product obtained by curing a composition obtained by mixing the first liquid and the second liquid of the kit according to claim 6.

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