Compositions, kits, and cured products

Abstract

The present invention provides 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 cured product of the composition. [Solution] A composition is provided 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). In the formula, R1 to R4 each independently represent an alkyl group having 1 to 4 carbon atoms. R5 represents an alkyl group having 1 to 16 carbon atoms. n is an integer from 0 to 4. TIFF2026123586000014.tif53170

Description

Technical Field

[0005]

[0001] The present invention relates to a composition, a kit, and a cured product.

Background Art

[0002] In recent years, cured epoxy resins have been developed for uses such as automotive parts and aircraft parts. When an epoxy resin composition is used for the above uses, the cured product obtained by curing the epoxy resin composition is required to have a high glass transition temperature and a high elastic modulus even at high temperatures.

[0003] Non-Patent Document 1 describes an examination of the influence of the steric hindrance of an amine on the physical properties of a cured product when an amine is used as a curing agent for bisphenol A type diglycidyl ether. According to this document, when an amine in which a hydrogen atom bonded to a carbon atom adjacent to the amino group of m-xylylenediamine is substituted with a methyl group is used as a curing agent, the glass transition temperature is higher than when m-xylylenediamine is used as a curing agent.

[0004] Non-Patent Document 2 describes an examination of the influence of the steric hindrance of an amine on the physical properties of a cured product when an aliphatic amine and an aromatic amine are used as curing agents for bisphenol A type diglycidyl ether. According to this document, it is described that the hindered amine epoxy cured product has a higher glass transition temperature and rubber elastic modulus than the unhindered amine epoxy cured product.

Prior Art Documents

Non-Patent Documents

[0005]

Non-Patent Document 1

[0006] [Non-Patent Document 2] THE EFFECTS OF STERIC HINDRANCE ON PHYSICAL PROPERTIES IN AMINE-CURED EPOXIES, Journal of Applied Polymer Science, 1988, vol 35(5), 1367. [Overview of the Initiative] [Problems that the invention aims to solve]

[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] Therefore, the present inventors conducted diligent studies to solve the above problems and 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 high-temperature modulus, specifically, a high temperature at which the modulus drops to 1 GPa, and thus completed this disclosure.

[0009] 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. [Means for solving the problem]

[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] [ka] [In the formula, R1 to R4 each independently represent an alkyl group having 1 to 4 carbon atoms. R5 represents an alkyl group having 1 to 16 carbon atoms. n is an integer of 0 to 4.]

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

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

[0015] [Chemical formula] [[ID=(20]]

[0016] [4] The composition according to any one of [1] to [3], wherein the epoxy resin contains the tetrafunctional epoxy resin and a 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 with respect to 100 parts by mass of the epoxy resin. <(

[0019] [Chemical formula] [In the formula, R1 to R4 each independently represent an alkyl group having 1 to 4 carbon atoms. Rt represents an alkyl group having 1 to 16 carbon atoms. n is an integer of 0 to 4.]

[0020] [7] A cured product obtained by curing the composition according to any one of [1] to [5].

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

Advantages of the Invention

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

Brief Description of the Drawings

[0023] [Figure 1] It is a diagram showing the storage elastic modulus (G’) [GPa] and the loss tangent (tanδ) of a cured product obtained by curing the composition of Example 4.

Modes for Carrying Out the Invention

[0024] Hereinafter, embodiments of the present disclosure will be described in detail.

[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 1 part by mass as the lower limit value and 10 parts by mass as the upper limit value.

[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 an 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.

[0028] ≪Tetrafunctional epoxy resin≫ One embodiment of the composition according to the present disclosure includes a tetrafunctional epoxy resin as the epoxy resin. In the present disclosure, "tetrafunctional epoxy resin" is a monomer of an epoxy compound having four epoxy groups (hereinafter also referred to as a tetrafunctional epoxy compound). "Tetrafunctional" means that one molecule of the epoxy compound has four epoxy groups.

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

[0030] [ka]

[0031] The content of the tetrafunctional epoxy compound represented by the chemical formula (B-1) may be 95 to 100% by mass, preferably 98 to 100% by mass, more preferably 99 to 100% by mass, and even more preferably 100% by mass, based on 100 parts by mass of the tetrafunctional epoxy resin. The upper and lower limits of the above range can be any combination.

[0032] The aforementioned tetrafunctional epoxy resin may be used individually or in combination of two or more types. The content of the quadrifunctional epoxy resin may be 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 and lower limits of the above range can be any combination. From the viewpoint of obtaining a cured product with a high glass transition temperature and a high high-temperature modulus, the content of the quadrafunctional epoxy resin is preferably 10 parts by mass or more, and more preferably 25 parts by mass or more, per 100 parts by mass of the epoxy resin. From the viewpoint of obtaining a cured product with a low water absorption rate, the content of the tetrafunctional epoxy resin 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, per 100 parts by mass of the epoxy resin. The upper and lower limits of the above range can be arbitrarily combined.

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

[0034] [ka] [In the formula, X is an alkylene group having 1 to 4 carbon atoms, -SO2-, or a divalent group to which these are bonded. m is a non-negative integer.]

[0035] In the general formula (B-2) above, X may be -CH2-, -C(CH3)2-, or -SO2-, with -C(CH3)2- being particularly preferred. In the general formula (B-2) above, m may be 0, 1, 2, or 3.

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

[0037] The aforementioned bifunctional epoxy resin may be used individually or in combination of two or more types. The content of the bifunctional epoxy resin 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 the epoxy resin. The upper and lower limits of the above range can be any combination.

[0038] The content of the bifunctional epoxy resin 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 mass of the tetrafunctional epoxy resin and the bifunctional epoxy resin. The upper and lower limits of the above range can be any combination.

[0039] The content of the tetrafunctional epoxy resin 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 bifunctional epoxy resin. The upper and lower limits of the above range can be combined arbitrarily. From the viewpoint of obtaining a cured product with a high glass transition temperature, the content of the tetrafunctional epoxy resin is preferably 10 parts by mass or more, and more preferably 25 parts by mass or more, based on 100 parts by mass of the total mass of the tetrafunctional epoxy resin and the bifunctional epoxy resin. From the viewpoint of obtaining a cured product with a low water absorption rate, the content of the tetrafunctional epoxy resin 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 mass of the tetrafunctional epoxy resin and the bifunctional epoxy resin. The upper and lower limits of the above range can be combined arbitrarily.

[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 the 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 include epoxy resins other than the tetrafunctional epoxy resin and the bifunctional epoxy resin (other epoxy resins). Other epoxy resins include polyfunctional epoxy resins (excluding the aforementioned tetrafunctional epoxy resins) that contain 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, and aromatic aminophenol-type epoxy resins. The above-mentioned polyfunctional epoxy resins may be used individually or in combination of two or more types.

[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 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 any combination.

[0046] <Hardening agent> The composition relating 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 epoxy resin and has the effect of curing it.

[0047] [ka] [In the formula, R1 to R4 each independently represent an alkyl group having 1 to 4 carbon atoms. R5 represents an alkyl group having 1 to 16 carbon atoms. n is an integer from 0 to 4.]

[0048] Each of the alkyl groups R1 to R4 may independently be linear or branched. The alkyl groups R1 to R4 can be any of the following, independently: methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, sec-butyl group, isobutyl group, and tert-butyl group. Among these, the alkyl group R1 to R4 may be a methyl group.

[0049] The alkyl group in R5 may be in the form of a chain, a cyclic structure, or a combination of these. The linear alkyl group in R5 may be linear or branched. Examples of the linear alkyl group in R5 include, in addition to the alkyl groups listed for R1 to R4, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, and their isomers. The alkyl group in the cyclic structure of R5 may be monocyclic or polycyclic. Examples of monocyclic alkyl groups in R5 include cycloheptyl groups, cyclohexyl groups, and other cycloalkanes from which one hydrogen atom has been removed. Examples of polycyclic alkyl groups in R5 include decalin and adamantane with one hydrogen atom removed. When n is an integer greater than or equal to 2, each R5 can be the same or different.

[0050] 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, per 100 parts by mass of the curing agent. The upper and lower limits of the range can be any combination.

[0051] The content of the curing agent 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 in the epoxy resin. The upper and lower limits of the above range can be arbitrarily combined. When the content of the curing agent is within the above range, the glass transition temperature of the resulting cured product increases, the high-temperature modulus increases, and the water absorption rate is kept low.

[0052] <<Other hardening agents>> The compositions relating to this disclosure may include, in addition to the curing agent represented by the general formula (A), other curing agents. 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] The aforementioned other curing agents may be used individually or in combination of two or more types. The content of the other curing agent 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 mass of the curing agent represented by the general formula (A) and the other curing agent. The upper and lower limits of the 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 mass 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.

[0055] The content of the curing agent is set such that, per 1 mole 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 agent is in the range of 0.8 to 1.1 moles, preferably 0.9 to 1.05 moles, and more preferably 0.95 to 1.0 moles. The upper and lower limits of the range can be arbitrarily combined.

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

[0057] Inorganic fillers The 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 colorants include carbon black and pigments.

[0059] <<Stress Relief Agent>> Examples of stress-relaxing 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 components can be used as coupling agents, thixotropes, and other flow-modifying components, as well as defoaming agents, flame retardants, and the like.

[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), wherein the content of the tetrafunctional epoxy resin is 10 to 100 parts by mass per 100 parts by mass of the epoxy resin. The cured product obtained by curing the composition of this embodiment has a high glass transition temperature and a high high-temperature modulus. Furthermore, generally, as the crosslinking density of the cured product increases and the glass transition temperature rises, the water absorption rate increases. On the other hand, the cured product of the composition of this embodiment has 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] [ka] [In the formula, R1 to R4 each independently represent an alkyl group having 1 to 4 carbon atoms. R5 represents an alkyl group having 1 to 16 carbon atoms. n is an integer from 0 to 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, for every 1 mole of epoxy groups in the epoxy resin contained in the first liquid, 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 mole, preferably 0.9 to 1.05 mole, and more preferably 0.95 to 1.0 mole. When the mixing ratio of the first liquid and the second liquid is within the above range, the resulting cured product has a higher glass transition temperature, a higher high-temperature modulus, and a lower 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. Furthermore, generally, as the crosslinking density of the cured product increases and the glass transition temperature rises, the water absorption rate also increases. On the other hand, with the kit of this embodiment, the resulting cured product has a high glass transition temperature while keeping the increase in water absorption rate 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. The method for producing the cured product is not particularly specified. From a process viewpoint, curing by heating is preferred.

[0068] [Measurement of the glass transition temperature of hardened material] The glass transition temperature of the cured product in this embodiment can be the temperature of the peak top of the loss tangent (tanδ) obtained from the dynamic viscoelasticity measurement of the cured product specimen.

[0069] <Preparation of hardened material> 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 hardened material obtained in the above <Preparation of Hardened Material> is cut into pieces measuring 10 mm in width and 25 mm in length to be used as test specimens. The dynamic viscoelasticity of the aforementioned test specimen 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)). The higher the glass transition temperature, the better the heat resistance.

[0071] <Dynamic viscoelasticity measurement conditions> Dynamic viscoelasticity measuring device: MCR301 (manufactured by Anton Paar) Distortion: 0.01% Frequency: 1Hz Measurement temperature: 40℃~300℃ 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 a cured material is 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," which is 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] [Measuring the water absorption rate of hardened material] The test specimens prepared in the above <Preparation of Test Specimens> are vacuum-dried at 100°C for 2 hours. The mass of the test specimens after vacuum drying is measured. Next, the test specimens are allowed to absorb water under the following water absorption conditions, and the mass of the test specimens 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 intake device: EHS-222 (manufactured by ESPEC) Temperature: 120℃ 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 is a cured product of the above-described composition, and therefore has a high glass transition temperature and a high high-temperature modulus. Furthermore, generally, as the crosslinking density of a cured product increases and the glass transition temperature rises, the water absorption rate also increases. On the other hand, with the cured product of this embodiment, the glass transition temperature is increased while the increase in water absorption rate is kept low. [Examples]

[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 hardening agent> A reaction solution was prepared by adding 120 g of 1,3-bis(2-isocyanato-2-propyl)benzene to 1000 g of 19% hydrochloric acid. The prepared reaction solution was stirred at 85°C for 6.5 hours, and then air-cooled to approximately 25°C. The reaction solution was adjusted to pH 12 by adding aqueous sodium hydroxide solution. 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 the above <Synthesis of Curing Agent> and the epoxy resin were mixed in the mass ratio shown in Table 1 to prepare the composition. The epoxy resin used is shown. (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] [Table 1]

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

[0083] <Preparation of hardened material> 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] [Table 2]

[0085] <Preparation of test specimens> The 1 mm thick sheet-like cured material obtained in the above <Preparation of Cured Material> was cut into pieces measuring 10 mm in width and 25 mm in length to be used as test specimens. The dynamic viscoelasticity of the aforementioned test specimen was 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)) and is shown in Table 3.

[0086] <Dynamic viscoelasticity measurement conditions> Dynamic viscoelasticity measuring device: MCR301 (manufactured by Anton Paar) Distortion: 0.01% Frequency: 1Hz Measurement temperature: 40℃~300℃ Heating rate: 5°C / min

[0087] [Measurement of the temperature at which the elastic modulus of a 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, as obtained by the dynamic viscoelasticity measurement described above. Table 3 shows the temperature (°C) at which the storage modulus (G') of the obtained cured product is 1 GPa.

[0088] [Measuring the water absorption rate of hardened material] The water absorption rate of the cured material was measured using 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 rate (%) is shown in Table 3.

[0089] <Water absorption measurement conditions> Water intake device: EHS-222 (manufactured by ESPEC) Temperature: 120℃ Relative humidity: 100%RH Water absorption time: 62 hours

[0090] [Table 3] 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. [Industrial applicability]

[0091] 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.

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