Epoxy resins, curable resin compositions, and their cured forms, as well as carbon fiber reinforced composites.

Abstract

This invention provides an epoxy resin with high heat resistance and high flexural modulus, a curable resin composition, and cured products thereof, as well as a carbon fiber reinforced composite material. An epoxy resin is represented by the following formula (1), having an epoxy equivalent of 228 g / eq. or more and 237 g / eq. or less. (In formula (1), n ​​is the average of repeated numbers, representing a real number where 1 < n < 15.)

Description

Technical Field

[0001] This invention relates to an epoxy resin, a curable resin composition, cured products thereof, and carbon fiber reinforced composite materials. Background Technology

[0002] Epoxy resins, through curing with various hardeners, form cured products with excellent mechanical properties, water resistance, chemical resistance, heat resistance, and electrical properties, and are used in a wide range of fields such as adhesives, coatings, laminates, molding materials, and casting materials. Carbon fiber reinforced plastic (CFRP), a composite material made by impregnating reinforcing fibers with epoxy resin and hardeners as the matrix resin and then curing them, has seen increasing demand in recent years due to its lightweight and high-strength properties. It is widely used in aircraft structural components, windmill blades, automobile exterior panels, integrated circuit (IC) trays, and computer applications such as notebook computer housings. In particular, its lightweight and high-strength properties make it suitable for use as a matrix resin in aircraft applications.

[0003] In recent years, the requirements for CFRP properties have become more stringent, especially in the case of structural materials used in aerospace or vehicles, where resins with superior heat resistance and elastic modulus are required (Patent Document 1, Patent Document 2).

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2010-275492

[0007] Patent Document 2: Japanese Patent Application Publication No. 2022-173168

[0008] Patent Document 3: Japanese Patent Application Publication No. 2007-211254 Summary of the Invention

[0009] The problem that the invention aims to solve

[0010] Patent Document 3 describes an epoxy resin with low water absorption. However, the epoxy resin described in Patent Document 3 has low heat resistance and low elastic modulus, making it difficult to use as a CFRP material.

[0011] The present invention is made in view of the above circumstances, and its object is to provide an epoxy resin, a curable resin composition, and the cured products thereof, as well as a carbon fiber reinforced composite material, having high heat resistance and high flexural modulus.

[0012] Technical means to solve the problem

[0013] That is, the present invention is the content shown in [1] to [8] below. In addition, in the present invention, "(numerical value 1) to (numerical value 2)" means including the upper limit value and the lower limit value. [1]

[0015] An epoxy resin is represented by the following formula (1), having an epoxy equivalent of 228 g / eq. or more and 237 g / eq. or less.

[0016] [Chemistry 1]

[0017]

[0018] (In equation (1), n ​​is the average of the number of repetitions, representing a real number where 1 < n < 15) [2]

[0020] An epoxy resin is represented by the following formula (1), wherein when the epoxy equivalent is set as a and the softening point is set as b, a / b is 3.0 or more and 3.4 or less.

[0021] [Chemistry 2]

[0022]

[0023] (In equation (1), n ​​is the average of the number of repetitions, representing a real number where 1 < n < 15) [3]

[0025] The epoxy resin described in the preceding paragraph [1] or [2] contains a biomass content of 50% or more. [4]

[0027] A curable resin composition comprising an epoxy resin according to any one of the preceding items [1] to [3] and a curing agent. [5]

[0029] According to the curing resin composition described in the preceding paragraph [4], wherein the curing agent is an amine curing agent. [6]

[0031] A curable resin composition comprising an epoxy resin mixture according to any one of the preceding items [1] to [3] and at least one selected from curing accelerators, polymerization initiators, epoxy resins other than those represented by the epoxy resin of formula (1), active ester compounds, phenolic resins, polyphenylene ether compounds, compounds having vinyl unsaturated bonds, isocyanate resins, polyamide resins, maleimide compounds, cyanate ester resins, polyimide resins, polybutadiene and its modified forms, polystyrene and its modified forms, polyethylene and its modified forms, and benzoxazine compounds. [7]

[0033] A hardened material formed by hardening according to the hardening resin composition described in the preceding paragraph [4] or [5]. [8]

[0035] A carbon fiber reinforced composite material is formed by curing the curable resin composition described in the preceding paragraph [4] or [5].

[0036] The effects of the invention

[0037] The present invention provides epoxy resins, curable resin compositions, and their cured forms having high heat resistance and high flexural modulus, as well as carbon fiber reinforced composite materials. Attached Figure Description

[0038] [ Figure 1 [] indicates the evaluation results of Example 1, Comparative Examples 1 to 2. Detailed Implementation

[0039] Hereinafter, embodiments of the present invention (hereinafter also referred to as "this embodiment") will be described in further detail.

[0040] The epoxy resin in this embodiment is represented by the following formula (1).

[0041] [Chemistry 3]

[0042]

[0043] (In equation (1), n ​​is the average of the number of repetitions, representing a real number where 1 < n < 15)

[0044] In formula (1), the value of n can be calculated based on the number average molecular weight of the epoxy resin determined by gel permeation chromatography (GPC, detector: RI (refractive index)) or the area ratio of the separated peaks. n is preferably a real number of 1 < n < 15, more preferably 1 < n < 10, and particularly preferably 1 < n < 5.

[0045] In this embodiment, the epoxy equivalent of the epoxy resin is preferably 228 g / eq. or more and 237 g / eq. or less, more preferably 230 g / eq. or more and 236 g / eq. or less, and even more preferably 231 g / eq. or more and 235 g / eq. or less. If the epoxy equivalent is 228 g / eq. or more, it exhibits high heat resistance; if it is 237 g / eq. or less, it exhibits high flexural modulus. In other words, by having an epoxy equivalent of 228 g / eq. or more and 237 g / eq. or less, both high heat resistance and high flexural modulus can be achieved.

[0046] The softening point of the epoxy resin represented by formula (1) is preferably 67°C or higher and 100°C or lower, and more preferably 70°C or higher and 80°C or lower. If the softening point is 67°C or higher, the resin will not clump together even without refrigeration and can be stored at room temperature, which is preferable in terms of storage. If the softening point is higher than 100°C, it is difficult to mix evenly with hardeners, polymerization initiators, fillers, etc., and it is easy to become poorly hardened.

[0047] In this embodiment, the epoxy resin is preferably such that, when the epoxy equivalent is set as 'a' and the softening point is set as 'b', the ratio of a / b is 3.0 or higher and 3.4 or lower, and more preferably 3.1 or higher and 3.3 or lower. If a / b is 3.4 or lower, the epoxy equivalent is lower than a certain softening point, thus the curing density is higher, and the heat resistance, thermal decomposition resistance, and elastic modulus become better. On the other hand, if a / b is less than 3.0, the softening point becomes too high compared to the epoxy equivalent, the molecular movement is restricted during the curing reaction, and the curing becomes incomplete, thus reducing the heat resistance and thermal decomposition resistance. That is, when it is 3.0 to 3.4, a balance between curing density and curing reaction can be achieved, and excellent properties can be exhibited.

[0048] The cured epoxy resin of this embodiment exhibits high heat resistance and a high flexural modulus. The flexural modulus is preferably 3.0 GPa to 4.0 GPa. If the flexural modulus is less than 3.0 GPa, the strength of the carbon fiber reinforced composite material will be insufficient, leading to reduced reliability, and therefore this is not preferred. Furthermore, the flexural modulus of this embodiment is measured using the method described in the examples below.

[0049] Heat resistance can be evaluated by the 5% weight loss temperature and the glass transition temperature (Tg). The 5% weight loss temperature is preferably 295°C or higher. The glass transition temperature (Tg) is preferably 210°C or higher and 300°C or lower, more preferably 215°C or higher and 250°C or lower, and even more preferably 216°C or higher and 230°C or lower. If the heat resistance is less than 210°C, it will be difficult to adapt to components requiring heat resistance, such as those around aircraft engines. During use, the resin will soften and its mechanical strength will significantly decrease, leading to material breakage, which is therefore undesirable. Furthermore, the heat resistance of epoxy resin is generally related to the crosslinking density; a higher crosslinking density results in higher heat resistance. That is, if the heat resistance exceeds 300°C, the crosslinking density becomes high, and the cured material becomes brittle, which is also undesirable. In addition, the 5% weight loss temperature and the glass transition temperature (Tg) of this embodiment are measured using the methods described in the examples described later.

[0050] From an environmental perspective, the biomass content of the epoxy resin in this embodiment is preferably 50% or more. While there is no particular upper limit to the biomass content, and it can be 100%, 80% is preferred for consideration of both the properties of the cured material. A high biomass content also reduces the amount of fossil fuels such as petroleum used, thus contributing to the sustainable use of resources. Therefore, it is preferable that the biomass content is also high in the curable resin composition after mixing with other materials; specifically, 20% or more, and more preferably 30% or more. The biomass content of this embodiment is measured using the method described in the examples described later.

[0051] The epoxy resin represented by formula (1) can be obtained by reacting the phenolic resin represented by formula (2) with epihaloalcohol.

[0052] [Chemistry 4]

[0053]

[0054] (In equation (2), n is the average of the number of repetitions, representing a real number where 1 < n < 15)

[0055] The preferred range of n in equation (2) is the same as that in equation (1).

[0056] The epihalool is readily available from the market. The amount of epihalool used is preferably 2.0 to 10 moles relative to 1 mole of the hydroxyl groups in the raw phenol mixture, more preferably 3.0 to 8.0 moles, and even more preferably 3.5 to 6.0 moles. Epihalools that can be used in this embodiment include, preferably, epichlorohydrin, α-methylepiochlorohydrin, β-methylepiochlorohydrin, epibromohydrin, etc., and particularly preferably, epichlorohydrin, which is readily available industrially.

[0057] In the reaction, an alkali metal hydroxide can be used as a catalyst to promote the epoxidation process. Examples of usable alkali metal hydroxides include sodium hydroxide and potassium hydroxide; both solid and aqueous solutions can be used. In this embodiment, particularly in terms of solubility and operability, a solid component formed into flakes is preferred. The amount of alkali metal hydroxide used is preferably 0.90 to 1.5 mol relative to 1 mol of hydroxyl groups in the phenol mixture, more preferably 0.95 to 1.25 mol, and even more preferably 0.99 to 1.15 mol.

[0058] In addition, to promote the reaction, quaternary ammonium salts such as tetramethylammonium chloride, tetramethylammonium bromide, and trimethylbenzylammonium chloride can be added as catalysts. The amount of quaternary ammonium salt used is preferably 0.1 g to 15 g, more preferably 0.2 g to 10 g, relative to 1 mole of the hydroxyl groups in the phenolic mixture.

[0059] The reaction temperature is preferably 30°C to 90°C, more preferably 35°C to 80°C. Particularly in this embodiment, to achieve higher purity epoxidation, a temperature of 50°C or higher is preferred, and particularly preferably 60°C or higher. The reaction time is preferably 0.5 hours to 10 hours, more preferably 1 hour to 8 hours, and particularly preferably 1 hour to 3 hours. If the reaction time is too short, the reaction cannot proceed completely; if the reaction time is too long, byproducts will be generated, which is therefore undesirable.

[0060] The reaction products of these epoxidation reactions are washed with water, or the epihalohydrins or solvents are removed under heating and reduced pressure without washing. Alternatively, to produce epoxy resins with fewer hydrolyzable halogens, ketone compounds with 4 to 7 carbon atoms (e.g., methyl isobutyl ketone, methyl ethyl ketone, cyclopentanone, cyclohexanone, etc.) can be used as solvents to dissolve the recovered epoxy resin, and an aqueous solution of alkali metal hydroxides such as sodium hydroxide or potassium hydroxide is added to carry out the reaction, ensuring reliable ring closure. In this case, the amount of alkali metal hydroxide used is preferably 0.01 to 0.3 mol, more preferably 0.05 to 0.2 mol, relative to 1 mol of hydroxyl groups in the phenol mixture used in the epoxidation. The reaction temperature is preferably 50°C to 120°C, and the reaction time is preferably 0.5 to 2 hours.

[0061] After the reaction is complete, the generated salt is removed by filtration and washing with water, and then the solvent is removed by distillation under heating and reduced pressure, thereby obtaining the epoxy resin of this embodiment.

[0062] As a method for synthesizing the phenolic resin represented by formula (2), when the reaction (condensation) of furfural and phenol is carried out, the amount of phenol is preferably in the range of 1.5 mol to 20 mol relative to 1 mol of furfural, and particularly preferably in the range of 3 mol to 10 mol.

[0063] Examples of phenols include catechol, resorcinol, and hydroquinone as disubstituted phenols, and phenol, cresol, and xylenol as monosubstituted phenols. They can be used alone or in combination with two or more.

[0064] Examples of solvents include methanol, ethanol, propanol, isopropanol, toluene, and xylene, but these are not limited to. A single solvent or two or more solvents can be used in combination. When using a solvent, the amount used is preferably in the range of 5 to 500 parts by weight relative to 100 parts by weight of phenol, and more preferably in the range of 10 to 300 parts by weight.

[0065] In the condensation reaction, an alkaline catalyst is preferred. While acidic catalysts can also be used for condensation, furfural reacts with itself, resulting in more byproducts. Alternatively, organometallic compounds can be used, but this is less costly. Specific examples of alkaline catalysts include: alkali metal hydroxides such as lithium hydroxide, sodium hydroxide, and potassium hydroxide; alkaline earth metal hydroxides such as magnesium hydroxide and calcium hydroxide; alkali metal alkoxides such as sodium methoxide, sodium ethoxide, potassium methoxide, and potassium tert-butoxide; and alkaline earth metal alkoxides such as magnesium methoxide and magnesium ethoxide, but these are not limited to these; two or more catalysts can be used alone or in combination. The amount of catalyst used relative to 1 mole of phenol is preferably 0.005 to 2.0 moles, more preferably 0.01 to 1.1 moles.

[0066] The condensation reaction in the presence of these alkaline catalysts is preferably carried out in the range of 40°C to 180°C, particularly preferably in the range of 80°C to 165°C, and the reaction time is preferably selected in the range of 0.5 hours to 10 hours. The reaction product thus obtained is neutralized or repeatedly washed with water in the presence of a solvent to make the system neutral, the water is separated and drained, and the solvent and unreacted substances are removed under heating and reduced pressure, thereby obtaining the phenolic resin represented by formula (2).

[0067] The curable resin composition of this embodiment contains a curing agent. Examples of usable curing agents include amine-based curing agents, acid anhydride-based curing agents, amide-based curing agents, and phenol-based curing agents.

[0068] In the curable resin composition of this embodiment, an amine curing agent is preferred, particularly in order to achieve a balanced relationship between the resin viscosity of the curable resin composition and the heat resistance of the cured resin. As an amine curing agent, 3,3'-diaminodiphenyl sulfone (3,3'-DDS), 4,4'-diaminodiphenyl sulfone (4,4'-DDS), and diaminodiphenylmethane (diaminodiphenyl sulfone) can be used. methane (DDM), 3,3'-diisopropyl-4,4'-diaminodiphenylmethane, 3,3'-di-tert-butyl-4,4'-diaminodiphenylmethane, 3,3'-diethyl-5,5'-dimethyl-4,4'-diaminodiphenylmethane, 3,3'-diisopropyl-5,5'-dimethyl-4,4'-diaminodiphenylmethane, 3,3'-di-tert-butyl-5,5'-dimethyl-4,4'-diaminodiphenylmethane, 3,3',5,5'-tetraethyl-4,4'-diaminodiphenylmethane (3,3',5,5'-tetraethyl- 4,4'-diaminodiphenylmethane (TEDDM), 3,3'-diisopropyl-5,5'-diethyl-4,4'-diaminodiphenylmethane, 3,3'-di-tert-butyl-5,5'-diethyl-4,4'-diaminodiphenylmethane, 3,3',5,5'-tetraisopropyl-4,4'-diaminodiphenylmethane, 3,3'-di-tert-butyl-5,5'-diisopropyl-4,4'-diaminodiphenylmethane, 3,3',5,5'-tetra-tert-butyl-4,4'-diaminodiphenylmethane, diaminodiphenyl ether (diaminodiphenylmethane) Diphenyl ether (DADPE), bis-aniline, benzyl dimethylaniline, 2-(dimethylaminomethyl)phenol (DMP-10), 2,4,6-tris(dimethylaminomethyl)phenol (DMP-30), 2-ethylhexanoate of 2,4,6-tris(dimethylaminomethyl)phenol, etc. Additionally, examples include: aniline phenolic varnish, o-ethylaniline phenolic varnish, aniline resin obtained by the reaction of aniline with xylylene chloride, and aniline resin obtained by the polycondensation of aniline with substituted biphenyls (4,4'-bis(chloromethyl)-1,1'-biphenyl and 4,4'-bis(methoxymethyl)-1,1'-biphenyl, etc.) or substituted phenyls (1,4-bis(chloromethyl)benzene, 1,4-bis(methoxymethyl)benzene and 1,4-bis(hydroxymethyl)benzene, etc.).

[0069] Examples of anhydride-based curing agents include: phthalic anhydride, trimellitic anhydride, pyromellitic anhydride, maleic anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylnadic anhydride, hexahydrophthalic anhydride, and methylhexahydrophthalic anhydride.

[0070] Examples of amide-based curing agents include dicyandiamide and polyamide resins synthesized from dimers of linolenic acid and ethylenediamine.

[0071] Examples of phenolic curing agents include: polyphenols (bisphenol A, bisphenol F, bisphenol S, fluorenebisphenol, terpene diphenol, 4,4'-dihydroxybiphenyl, 2,2'-dihydroxybiphenyl, 3,3',5,5'-tetramethyl-(1,1'-biphenyl)-4,4'-diphenol, hydroquinone, resorcinol, naphthol, tris-(4-hydroxyphenyl)methane, and 1,1,2,2-tetra(4-hydroxyphenyl)ethane, etc.); phenols (e.g., phenol, alkyl-substituted phenols, naphthol, alkyl-substituted naphthols, dihydroxybenzene, and dihydroxynaphthalene, etc.) and aldehydes (formaldehyde, acetaldehyde, benzaldehyde, p-hydroxybenzene, o-hydroxybenzene, and furfural, etc.), ketones (p-hydroxybenzene...). Phenolic resins obtained by condensation of acetone and o-hydroxyacetophenone, or dienes (dicyclopentadiene and tricyclopentadiene, etc.); phenolic resins obtained by polycondensation of the phenols with substituted biphenyls (4,4'-bis(chloromethyl)-1,1'-biphenyl and 4,4'-bis(methoxymethyl)-1,1'-biphenyl, etc.) or substituted phenyls (1,4-bis(chloromethyl)benzene, 1,4-bis(methoxymethyl)benzene and 1,4-bis(hydroxymethyl)benzene, etc.); modified versions of the phenols and / or the phenolic resins; halogenated phenols such as tetrabromobisphenol A and brominated phenolic resins.

[0072] In the curing resin composition of this embodiment, it is also preferable to use the phenolic resin represented by the formula (2) as the total amount or part thereof of the curing agent.

[0073] In the curable resin composition of this embodiment, the amount of curing agent used is preferably 0.7 to 1.2 equivalents relative to the epoxy group equivalent of the epoxy resin. If the amount is less than 0.7 equivalents or more than 1.2 equivalents relative to the epoxy group equivalent, there is a concern that curing becomes incomplete and good cured properties cannot be obtained.

[0074] In addition, a curing accelerator may be added to the curable resin composition of this embodiment as needed. The gelation time can also be adjusted by using a curing accelerator. Examples of usable curing accelerators include: imidazoles such as 2-methylimidazole, 2-ethylimidazole, and 2-ethyl-4-methylimidazole; tertiary amines such as 2-(dimethylaminomethyl)phenol and 1,8-diaza-bicyclo[5,4,0]undecene-7; phosphines such as triphenylphosphine; and metal compounds such as tin octoate. The curing accelerator is used in quantities of 0.01 to 5.0 parts by weight relative to 100 parts by weight of epoxy resin, as needed.

[0075] In the curable resin composition of this embodiment, other epoxy resins may also be formulated. Specific examples include: condensation polymers of phenols (phenol, alkyl-substituted phenols, aromatic-substituted phenols, naphthol, alkyl-substituted naphthols, dihydroxybenzene, alkyl-substituted dihydroxybenzene, dihydroxynaphthalene, etc.) and various aldehydes (formaldehyde, acetaldehyde, alkyl aldehydes, benzaldehyde, alkyl-substituted benzaldehyde, hydroxybenzene, naphthal, glutaraldehyde, o-phthalaldehyde, crotonaldehyde, cinnamaldehyde, etc.); polymers of phenols and various diene compounds (dicyclopentadiene, terpenes, vinylcyclohexene, norbornene, vinylnorbornene, tetrahydroindene, divinylbenzene, divinylbiphenyl, diisopropenylbiphenyl, butadiene, isoprene, etc.); and polymers of phenols and ketones (acetone, methyl ethyl ketone, methyl isobutyl ketone). Condensation polymers of acetophenone, benzophenone, etc.; phenolic resins obtained by condensation polymerization of phenols with substituted biphenyls (4,4'-bis(chloromethyl)-1,1'-biphenyl and 4,4'-bis(methoxymethyl)-1,1'-biphenyl, etc.) or substituted phenyls (1,4-bis(chloromethyl)benzene, 1,4-bis(methoxymethyl)benzene and 1,4-bis(hydroxymethyl)benzene, etc.); condensation polymers of bisphenols and various aldehydes; glycidyl ether epoxy resins obtained by glycidylating alcohols, etc.; alicyclic epoxy resins represented by 4-vinyl-1-cyclohexene diepoxide or 3,4-epoxycyclohexylmethyl-3,4'-epoxycyclohexane carboxylate, etc.; and tetraglycidyl diaminodiphenylmethane (tetraglycidyl) Glycidylamine epoxy resins, glycidyl ester epoxy resins, etc., represented by diamino diphenyl methane (TGDDM) or triglycidyl-p-aminophenol, are not limited to these.

[0076] In the curable resin composition of this embodiment, known additives may be formulated as needed. Specific examples of additives that can be used include: active ester compounds, phenolic resins, compounds having vinyl unsaturated bonds, isocyanate resins, polyamide resins, benzoxazine compounds, polybutadiene and its modified forms, modified acrylonitrile copolymers, polyphenylene ether compounds, polystyrene and its modified forms, polyethylene and its modified forms, polyimide resins, fluororesins, maleimide compounds, cyanate ester resins, silicone gels, silicone oils, and surface treatment agents for inorganic fillers such as silica, alumina, calcium carbonate, quartz powder, aluminum powder, graphite, talc, clay, iron oxide, titanium oxide, aluminum nitride, asbestos, mica, and glass powder, as well as fillers such as silane coupling agents, mold release agents, carbon black, phthalocyanine blue, phthalocyanine green, and other colorants.

[0077] Examples of active ester compounds include phenolic esters, thiophenolic esters, N-hydroxylamine esters, and esters of heterocyclic hydroxyl compounds.

[0078] Examples of polyphenylene ether compounds include SA-9000 (a polyphenylene ether compound with methacrylic acid groups manufactured by Saudi Arabia's Basic Industries Corporation (SABIC)) and OPE-2St 1200 (a polyphenylene ether compound with a styrene structure manufactured by Mitsubishi Gas Chemical Corporation).

[0079] Examples of compounds containing vinyl unsaturated bonds include: reaction products of phenolic resins with halogen compounds containing vinyl unsaturated bonds (chloromethylstyrene, allyl chloride, methylallyl chloride, acryloyl chloride, methacryloyl chloride, etc.); reaction products of phenols containing vinyl unsaturated bonds (2-allylphenol, 2-propenylphenol, 4-allylphenol, 4-propenylphenol, eugenol, isoeugenol, etc.) with halogen compounds (1,4-bis(chloromethyl)benzene, 4,4'-bis(chloromethyl)biphenyl, 4,4'-difluorobenzophenone, 4,4'-dichlorobenzophenone, 4,4'-dibromobenzophenone, cyanuric trichloroethylene, etc.); reaction products of epoxy resins or alcohols with (meth)acrylic acids (acrylic acid, methacrylic acid, etc.) and their acid-modified derivatives.

[0080] Examples of isocyanate resins include: aromatic diisocyanates such as terephthalic diisocyanate, isophthalic diisocyanate, p-xylene diisocyanate, m-xylene diisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 4,4'-diphenylmethane diisocyanate, and naphthalene diisocyanate; aliphatic or alicyclic diisocyanates such as isophorone diisocyanate, hexamethylene diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, hydrogenated xylene diisocyanate, norbornene diisocyanate, and lysine diisocyanate; polyisocyanates such as biuret bodies of one or more isocyanate monomers or isocyanates formed by trimerization of the aforementioned diisocyanate compounds; and polyisocyanates obtained by carbamate reaction of the aforementioned isocyanate compounds with polyol compounds.

[0081] Examples of maleimide compounds include: 4,4'-diphenylmethane bismaleimide, polyphenylmethane maleimide, m-phenylene bismaleimide, 2,2'-bis[4-(4-maleimide phenoxy)phenyl]propane, 3,3'-dimethyl-5,5'-diethyl-4,4'-diphenylmethane bismaleimide, 4-methyl-1,3-phenylene bismaleimide, 4,4'-diphenyl ether bismaleimide, 4,4'-diphenyl sulfone bismaleimide, 1,3-bis(3-maleimide phenoxy)benzene, 1,3-bis(4-maleimide phenoxy)benzene, and neophenolic maleimide compounds (Annilis). (Anilix) maleimide, manufactured by Mitsui Chemicals Fine Chemicals Co., Ltd.), biphenyl aralkyl type maleimide compounds (a compound solidified by solvent distillation of a resin solution containing maleimide compound (M2) under reduced pressure, as described in Example 4 of Japanese Patent Application Publication No. 2009-001783), diaminocumylbenzene type maleimide (maleimide compound described in International Publication No. 2020 / 054601), maleimide compounds having an indane structure described in Japanese Patent No. 6629692 or International Publication No. 2020 / 217679, and the "Material Stage" (MATERIAL) The maleimide compounds described in "Epoxy Resin CAS Number Story - Hardener CAS Number Memorandum No. 31 Bismaleimide (1)" or "Material Stage" Vol. 19, No. 2, 2019 "Epoxy Resin CAS Number Story - Hardener CAS Number Memorandum No. 32 Bismaleimide (2)" can be used alone or in combination with two or more. When formulating maleimide-based compounds, a curing accelerator may be formulated as needed, but the curing accelerators described above, or free radical polymerization initiators such as organic peroxides and azo compounds may be used.

[0082] Examples of cyanate ester resins include: dicyanophenyl, tricyanophenyl, dicyanonaphthalene, dicyanobiphenyl, 2,2'-bis(4-cyanophenyl)propane, bis(4-cyanophenyl)methane, bis(3,5-dimethyl-4-cyanophenyl)methane, 2,2'-bis(3,5-dimethyl-4-cyanophenyl)propane, 2,2'-bis(4-cyanophenyl)ethane, 2,2'-bis(4-cyanophenyl)hexafluoropropane, bis(4-cyanophenyl)sulfone, bis(4-cyanophenyl)sulfide, phenolic varnish cyanate ester, and resins in which the hydroxyl groups of a phenol-dicyclopentadiene cocondensate are converted to cyanate ester groups.

[0083] Examples of polyimide resins include: the diamine and tetracarboxylic dianhydrides (4,4'-(hexafluoroisopropyl)diphthalic anhydride, 5-(2,5-dioxotetrahydro-3-furanyl)-3-methyl-cyclohexene-1,2-dicarboxylic anhydride, pyromellitic dianhydride, 1,2,3,4-benzenetetracarboxylic dianhydride, 3,3',4,4'-benzophenonetetracarboxylic dianhydride, 2,2',3,3'-benzophenonetetracarboxylic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 3,3',4,4'-diphenylsulfonetetracarboxylic dianhydride, 2,2',3,3'-biphenyltetracarboxylic dianhydride, methylene-4,4'-diphthalic dianhydride, 1,1-ethylidene-4,4'-diphthalic dianhydride, 2,2'-propylene...). 1,2-Ethylene-4,4'-phthalic anhydride, 1,3-trimethylene-4,4'-phthalic anhydride, 1,4-tetramethylene-4,4'-phthalic anhydride, 1,5-pentamethylene-4,4'-phthalic anhydride, 4,4'-oxyphthalic anhydride, thio-4,4'-phthalic anhydride, sulfonyl-4,4'-phthalic anhydride, 1,3-bis(3,4-dicarboxyphenyl)phthalic anhydride, 1,3-bis(3,4-dicarboxyphenoxy)phthalic anhydride, 1,4-bis(3,4-dicarboxyphenoxy)phthalic anhydride, 1,3-bis[2-(3,4-dicarboxyphenyl)-2-propyl]phthalic anhydride 1,4-Bis[2-(3,4-dicarboxyphenyl)-2-propyl]phenyl dianhydride, bis[3-(3,4-dicarboxyphenoxy)phenyl]methane dianhydride, bis[4-(3,4-dicarboxyphenoxy)phenyl]methane dianhydride, 2,2-bis[3-(3,4-dicarboxyphenoxy)phenyl]propane dianhydride, 2,2-bis[4-(3,4-dicarboxyphenoxy)phenyl]propane dianhydride, bis(3,4-dicarboxyphenoxy)dimethylsilane dianhydride, 1,3-bis(3,4-dicarboxyphenyl)-1,1,3,3-tetramethyldisiloxane dianhydride, 2,3,6,7-naphthalenetetracarboxylic acid dianhydride, 1,4,5,8-naphthalenetetracarboxylic acid dianhydride, 1,2,5,6-naphthalenetetracarboxylic acid dianhydride, 3,4,9,10-perylenetetracarboxylic acid dianhydride 2,3,6,7-Anthracene tetracarboxylic dianhydride, 1,2,7,8-Phenylenite tetracarboxylic dianhydride, Ethylene tetracarboxylic dianhydride, 1,2,3,4-Butanetetracarboxylic dianhydride, 1,2,3,4-Cyclobutanetetracarboxylic dianhydride, Cyclopentanetetracarboxylic dianhydride, Cyclohexane-1,2,3,4-Tetracarboxylic dianhydride, Cyclohexane-1,2,4,5-Tetracarboxylic dianhydride, 3,3',4,4'-Dicyclohexyltetracarboxylic dianhydride, Carbonyl-4,4'-bis(cyclohexane-1,2-dicarboxylic acid) dianhydride, Methylene-4,4'-bis(cyclohexane-1,2-dicarboxylic acid) dianhydride, 1,2-Ethylene-4,4'-bis(cyclohexane-1,2-dicarboxylic acid) dianhydride, 1,1-Ethylene-4,4'-bis(cyclohexane-1,2-dicarboxylic acid) dianhydride, 2,2-Propylene-4,4'-bis(cyclohexane-1,2-dicarboxylic acid) dianhydride, oxy-4,4'-bis(cyclohexane-1,2-dicarboxylic acid) dianhydride, thio-4,4'-bis(cyclohexane-1,2-dicarboxylic acid) dianhydride, sulfonyl-4,4'-bis(cyclohexane-1,2-dicarboxylic acid) dianhydride, bicyclo[2,2,2]oct-7-ene-2,3,5,6-tetracarboxylic acid dianhydride, rel-[1S,5R,6R]-3-oxa Reactions of bicyclic [3,2,1]octane-2,4-dione-6-spiro-3'-(tetrahydrofuran-2',5'-dione), 4-(2,5-dioxotetrahydrofuran-3-yl)-1,2,3,4-tetrahydronaphthalene-1,2-dicarboxylic anhydride, ethylene glycol-bis-(3,4-dicarboxylic anhydride phenyl) ether, 4,4'-biphenylbis(triphenylamine monoester anhydride), 9,9'-bis(3,4-dicarboxyphenyl)fluorene dihydride, etc.

[0084] Examples of polybutadiene and its modified products, polystyrene and its modified products, and polyethylene and its modified products include: polybutadiene, hydroxyl-terminated polybutadiene, terminal (meth)acrylated polybutadiene, carboxylic acid-terminated polybutadiene, amine-terminated polybutadiene, styrene-butadiene rubber, RICON-100, RICON-181, RICON-184 (all manufactured by Cray Valley), 1,2-styrene-butadiene-styrene block copolymer (SBS) (manufactured by Nippon Soda), B-1000, B-2000, B-3000 (all manufactured by Nippon Soda); polystyrene, styrene-2-isopropenyl-2-oxazoline copolymer (Epocros RPS-1005, RP-61). All are manufactured by Nippon Catalyst Co., Ltd.), SEP (Styrene-Ethylene-Propylene copolymer) (Styrene-ethylene-propylene copolymer: Septon 1020, manufactured by Kuraray Co., Ltd.), SEPS (Styrene-Ethylene-Propylene-Styrene copolymer) (Styrene-ethylene-propylene-styrene copolymer: Septon 2002, Septon 2004F, Septon 2005, Septon 2006, Septon 2063, Septon 2104, all manufactured by Kuraray Co., Ltd.), SEEPS (Styrene-Ethylene / Ethylene-Propylene-Styreneblock) (Styrene-ethylene / ethylene-propylene-styrene block copolymers: Septon 4003, Septon 4044, Septon 4055, Septon 4077, Septon 4099, all manufactured by Kuraray) and SEBS (Styrene-Ethylene-Butylene-Styrene block copolymers: Septon 8004, Septon 8006, Septon 8007L)All are manufactured by Kuraray Corporation), SEEPS-ОH (a compound with hydroxyl groups at the end of a styrene-ethylene / ethylene-propylene-styrene block copolymer: Septon HG252, manufactured by Kuraray Corporation), SIS (Styrene-Isoprene-Styrene block copolymer): Septon 5125, Septon 5127, both manufactured by Kuraray Corporation), hydrogenated SIS (hydrogenated styrene-isoprene-styrene block copolymer: Hybrar 7125F, Hybrar 7311F, both manufactured by Kuraray Corporation), SIBS (Styrene-Isobutylene-Styrene block copolymer). (styrene-isobutylene-styrene block copolymers: SIBSTAR073T, SIBSTAR102T, SIBSTAR103T (all manufactured by Kaneka Corporation), Septon V9827 (manufactured by Kuraray Corporation); ethylene-propylene copolymers, ethylene-styrene copolymers, ethylene-propylene-ethylene norbornene copolymers (EBT manufactured by Mitsui Chemicals: K-8370EM, K-9330M, etc.), ethylene-propylene-vinyl norbornene copolymers (VNB-EPT manufactured by Mitsui Chemicals: PX-006M, PX-008M, PX-009M, etc.), ethylene-vinyl alcohol copolymers, ethylene-vinyl acetate copolymers, etc.

[0085] Examples of benzoxazine compounds include: benzoxazine Pd, Fa, ALP-d (all manufactured by Shikoku Chemical Co., Ltd.), JBZ-BA100N, JBZ-FA100N, JBZ-DP100N, JBZ-OP100N, JBZ-OP100D, JBZ-OP100I (all manufactured by JFE Chemical Co., Ltd.), and BTBz (manufactured by Japan Materials Research Institute Co., Ltd.).

[0086] The curable resin composition of this embodiment can be made into a varnish-like composition (hereinafter simply referred to as varnish) by adding an organic solvent. Examples of solvents used include: amide solvents such as γ-butyrolactone, N-methylpyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, and N,N-dimethylimidazolium ketone; sulfone solvents such as tetramethylene sulfone; ether solvents such as diethylene glycol dimethyl ether, diethylene glycol diethyl ether, propylene glycol, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, and propylene glycol monobutyl ether; ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone, cyclopentanone, and cyclohexanone; and aromatic solvents such as toluene and xylene. The concentration of the solid components of the solvent, excluding the solvent in the obtained varnish, is preferably in the range of 10% to 80% by weight, more preferably 20% to 70% by weight.

[0087] The curable resin composition of this embodiment can also be effectively used as resin sheets, prepregs, and carbon fiber reinforced composites.

[0088] The curable resin composition of this embodiment can be coated on one or both sides of a support substrate to serve as a resin sheet. Examples of coating methods include: casting, extruding resin from a nozzle or die using a pump or extruder and adjusting the thickness using a scraper, adjusting the thickness using a roller for calendering, and spraying using a sprayer. Furthermore, in the layer-forming process, heating can be performed simultaneously within a temperature range that avoids thermal decomposition of the curable resin composition. Additionally, calendering or grinding can be performed as needed. Examples of suitable support substrates include porous substrates such as paper, cloth, and non-woven fabrics; plastic films or sheets such as polyethylene, polypropylene, polyethylene terephthalate, and polyester films; meshes; foams; metal foils; and laminates thereof, but are not limited to these. The thickness of the support substrate is not particularly limited and can be appropriately determined according to the application.

[0089] The prepreg of this embodiment can be obtained by heating and melting the curable resin composition and / or resin sheet of this embodiment to reduce its viscosity and impregnating it in a fiber substrate.

[0090] Alternatively, a varnish-like curable resin composition can be impregnated in a fiber substrate and then heated and dried to obtain the prepreg of this embodiment. After the prepreg is cut into the desired shape and laminated, pressure is applied to the laminate using a compression molding method, autoclave molding method, sheet winding method, etc., while simultaneously heating and curing the curable resin composition to obtain the carbon fiber reinforced composite material of this embodiment. Alternatively, copper foil or an organic film can be laminated during the lamination of the prepreg.

[0091] Furthermore, regarding the molding method of the carbon fiber reinforced composite material of this embodiment, in addition to obtaining it by the method described above, it can also be obtained by a known method. For example, the following resin transfer molding (RTM) technique can also be used: a preform (a preform before resin impregnation) is prepared by cutting, stacking, and shaping a carbon fiber substrate (usually carbon fiber fabric), the preform is placed in a molding mold and the mold is closed, resin is injected to impregnate the preform and harden it, and then the mold is opened and the molded article is removed.

[0092] Alternatively, other RTM methods such as Vacuum Assisted Resin Transfer Molding (VaRTM), Seeman's Composite Resin Infusion Molding Process (SCRIMP), and Controlled Atmospheric Pressure Resin Infusion (CAPRI) as described in Japanese Patent Application Publication No. 2005-527410 can be used. In the CAPRI method, the resin supply tank is vented until the pressure is below atmospheric pressure, and cyclic compression is used to control the net forming pressure, thereby more appropriately controlling the resin injection process, especially the VaRTM method.

[0093] Furthermore, the following methods can also be used: a film stacking method in which resin sheets (films) are used to sandwich the fiber substrate; or a method in which powdered resin is attached to the reinforcing fiber substrate to improve impregnation; a forming method in which a flow layer or fluid slurry method is used to mix the resin in the fiber substrate (powder impregnated yarn); or a method in which resin fibers are woven into the fiber substrate.

[0094] Examples of carbon fibers include acrylic, pitch, and rayon fibers, among which acrylic carbon fibers with high tensile strength are preferred. As for the form of carbon fibers, twisted yarn, untwisted yarn, and untwisted yarn can be used, but to achieve a good balance between the formability and strength properties of the fiber-reinforced composite material, untwisted yarn or untwisted yarn is preferred.

[0095] Example

[0096] The following examples and embodiments are provided to further illustrate the present invention. The materials, processing methods, processing order, etc., shown below can be appropriately modified without departing from the spirit of the invention. Therefore, the scope of the present invention should not be limited by the specific examples shown below.

[0097] The analytical methods are conducted under the following conditions.

[0098] · Epoxy equivalent

[0099] The determination was performed using the method described in Japanese Industrial Standards (JIS) K-7236, and the unit is g / eq.

[0100] · Softening point

[0101] The measurements were performed according to the method in JIS K-7234, and the units are in °C.

[0102] • Biomass quality analysis (accelerator mass analysis method)

[0103] Calculated according to ASTM D6866-21. Unit: %.

[0104] GPC (Gel Permeation Chromatography)

[0105] Manufacturer: Waters

[0106] Tubing Strings: Protective tubing strings SHODEX GPC KF-601 (2 strings), KF-602, KF-602.5, KF-603

[0107] Flow rate: 1.23 ml / min.

[0108] Column temperature: 25℃

[0109] Solvent used: THF (Tetrahydrofuran)

[0110] Detector: RI (Differential Refraction Detector)

[0111] [Synthesis example 1]

[0112] 254 parts by weight of phenol, 63 parts by weight of water, and 27 parts by weight of sodium hydroxide were added to a flask containing a stirrer, reflux cooling tube, and stirring device. After stirring and dissolving, the mixture was heated to 110°C, and 133 parts by weight of furfural were added dropwise over 2 hours. After reacting at 110°C for 3 hours, the temperature was raised to 145°C. During the heating process, the distilled water was removed from the system. After reaching 145°C, the mixture was allowed to react for 4 hours. Subsequently, the mixture was cooled to 80°C, and 63 parts by weight of water were added, along with 4 parts by weight of phosphoric acid and 63 parts by weight of 35% hydrochloric acid for neutralization. After repeated washing with water, unreacted phenol was removed by distillation under heating and reduced pressure, thereby obtaining 205 parts by weight of the phenolic resin represented by formula (2). Relative to 78 parts by weight of the phenolic resin represented by formula (2), 254 parts by weight of epichlorohydrin (ECH, hereinafter the same), 64 parts by weight of dimethyl sulfoxide (DMSO, hereinafter the same), and 13 parts by weight of water were added to a reaction vessel. After heating, stirring, and dissolving, 23 parts by weight of flake sodium hydroxide were added in portions over 2 hours while maintaining the temperature at 45°C. The reaction was then carried out for another 2 hours at 45°C and another 60 minutes at 70°C. After repeated washing with water to remove byproduct salts and dimethyl sulfoxide, excess epichlorohydrin was distilled off from the oil layer under reduced pressure. 218 parts by weight of methyl isobutyl ketone were added to the residue for dissolution. The methyl isobutyl ketone solution was heated to 70°C, and 7 parts by weight of a 30% sodium hydroxide aqueous solution were added. After reacting for 1 hour, the reaction solution was repeatedly washed with water until the washing solution became neutral. Subsequently, methyl isobutyl ketone was removed from the oil layer by distillation under heating and reduced pressure, thereby obtaining 94 parts by weight of the epoxy resin represented by formula (1) (n in formula (1) is 3.9). The properties of the obtained epoxy resin are described in Table 1.

[0113] [Synthesis example 2]

[0114] 254 parts by weight of phenol, 63 parts by weight of water, and 27 parts by weight of sodium hydroxide were added to a flask containing a stirrer, reflux cooling tube, and stirring device. After stirring and dissolving, the mixture was heated to 110°C, and 133 parts by weight of furfural were added dropwise over 2 hours. After reacting at 110°C for 3 hours, the temperature was raised to 145°C. During the heating process, the distilled water was removed from the system. After reaching 145°C, the mixture was allowed to react for 4 hours. Subsequently, the mixture was cooled to 80°C, and 63 parts by weight of water were added, along with 4 parts by weight of phosphoric acid and 63 parts by weight of 35% hydrochloric acid for neutralization. After repeated washing with water, unreacted phenol was removed by distillation under heating and reduced pressure, thereby obtaining 205 parts by weight of the phenolic resin represented by formula (2). Relative to 78 parts by weight of the phenolic resin represented by formula (2), 181 parts by weight of ECH, 64 parts by weight of DMSO, and 13 parts by weight of water were added to a reaction vessel. After heating, stirring, and dissolving, 23 parts by weight of flake sodium hydroxide were added in portions over 2 hours while maintaining the temperature at 45°C. The reaction was then carried out for another 2 hours at 45°C and another 60 minutes at 70°C. The mixture was then repeatedly washed with water to remove byproduct salts and dimethyl sulfoxide. Excess epichlorohydrin was removed by distillation from the oil layer under reduced pressure. 218 parts by weight of methyl isobutyl ketone were added to the residue for dissolution. The methyl isobutyl ketone solution was heated to 70°C, and 7 parts by weight of a 30% sodium hydroxide aqueous solution were added. After reacting for 1 hour, the reaction solution was repeatedly washed with water until the washing solution became neutral. Subsequently, methyl isobutyl ketone was removed from the oil layer by distillation under heating and reduced pressure, thereby obtaining 92 parts by weight of the epoxy resin represented by formula (1) (n in formula (1) is 4.3). The properties of the obtained epoxy resin are described in Table 1.

[0115] [Synthesis example 3]

[0116] 254 parts by weight of phenol, 63 parts by weight of water, and 27 parts by weight of sodium hydroxide were added to a flask containing a stirrer, reflux cooling tube, and stirring device. After stirring and dissolving, the mixture was heated to 110°C and 90 parts by weight of furfural were added dropwise over 2 hours. After reacting at 110°C for 3 hours, the temperature was raised to 145°C. During the heating process, the distilled water was removed from the system. After reaching 145°C, the mixture was allowed to react for 4 hours. Subsequently, the mixture was cooled to 80°C, and 63 parts by weight of water were added, along with 4 parts by weight of phosphoric acid and 63 parts by weight of 35% hydrochloric acid for neutralization. After repeated washing with water, unreacted phenol was removed by distillation under heating and reduced pressure, thereby obtaining 120 parts by weight of the phenolic resin represented by formula (2). Relative to 78 parts by weight of the obtained phenolic resin, 254 parts by weight of ECH, 64 parts by weight of DMSO, and 13 parts by weight of water were added to a reaction vessel. After heating, stirring, and dissolving, 23 parts by weight of flake sodium hydroxide were added in portions over a period of 2 hours while maintaining the temperature at 45°C. The reaction was then carried out for another 2 hours at 45°C and a further 60 minutes at 70°C. The mixture was then repeatedly washed with water to remove byproduct salts and dimethyl sulfoxide. Excess epichlorohydrin was removed by distillation from the oil layer under reduced pressure. 218 parts by weight of methyl isobutyl ketone were added to the residue for dissolution. The methyl isobutyl ketone solution was heated to 70°C, and 7 parts by weight of a 30% sodium hydroxide aqueous solution were added. After reacting for 1 hour, the reaction solution was repeatedly washed with water until the washing solution became neutral. Subsequently, methyl isobutyl ketone was removed from the oil layer by distillation under heating and reduced pressure, thereby obtaining 90 parts by weight of the epoxy resin represented by formula (1) (n in formula (1) is 2.6). The properties of the obtained epoxy resin are described in Table 1.

[0117] [Example 1, Comparative Examples 1-2]

[0118] The epoxy resins obtained in Synthesis Examples 1 to 3 were used as the main agent, and 3,3',5,5'-tetraethyl-4,4'-diaminodiphenylmethane (TEDDM, manufactured by Tokyo Chemical Industry Co., Ltd., with an active hydrogen equivalent of 78 g / eq.) was used as the curing agent. The mixtures were prepared according to the weight ratios shown in Table 2, and cured at 160°C for 6 hours to produce a cured product. The evaluation results are recorded in Table 2 and... Figure 1 .

[0119] The determination of physical properties shall be carried out under the following conditions.

[0120] <Determination conditions for heat resistance (Tg)>

[0121] Thermomechanical Analysis (TMA) Apparatus: TMA Q400EM manufactured by TA Instruments

[0122] Heating rate: 2℃ / minute

[0123] Measurement temperature range: 25℃~300℃

[0124] Tg: The point at which the coefficient of thermal expansion changes is set as Tg.

[0125] <Heat Decomposition Resistance Test>

[0126] Measurement apparatus: TG / DTA6200, manufactured by Hitachi High-Tech Science, with oxygen injection rate of 200 mL / min and heating rate of 10℃ / min.

[0127] [Table 1]

[0128]

[0129] The biomass quality of Synthetic Example 3 was not determined.

[0130] [Table 2]

[0131]

[0132] According to Table 2, Figure 1 The results confirmed that the hardened material of the embodiment has high heat resistance and high flexural modulus.

Claims

1. An epoxy resin, represented by the following formula (1), having an epoxy equivalent of 228 g / eq. or more and 237 g / eq. or less, [Chemistry 1] (In equation (1), n ​​is the average of the number of repetitions, representing a real number where 1 < n < 15).

2. An epoxy resin, represented by the following formula (1), wherein when the epoxy equivalent is set as a and the softening point is set as b, a / b is 3.0 or more and 3.4 or less. [Chemistry 2] (In equation (1), n ​​is the average of the number of repetitions, representing a real number where 1 < n < 15).

3. The epoxy resin according to claim 1 or 2, wherein the biomass content is 50% or more.

4. A curable resin composition comprising an epoxy resin as described in any one of claims 1 to 3 and a curing agent.

5. The curable resin composition according to claim 4, wherein the curing agent is an amine-based curing agent.

6. A curable resin composition comprising an epoxy resin as described in any one of claims 1 to 3 and at least one selected from curing accelerators, polymerization initiators, epoxy resins other than those represented by formula (1), active ester compounds, phenolic resins, polyphenylene ether compounds, compounds having vinyl unsaturated bonds, isocyanate resins, polyamide resins, maleimide compounds, cyanate ester resins, polyimide resins, polybutadiene and its modified forms, polystyrene and its modified forms, polyethylene and its modified forms, and benzoxazine compounds.

7. A hardened material formed by hardening the hardening resin composition as described in claim 4.

8. A carbon fiber reinforced composite material, formed by curing the curable resin composition as described in claim 4.

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