Phenolic resins, epoxy resins, curable resin compositions, cured products, and carbon fiber reinforced composites

Abstract

This invention provides a phenolic resin with excellent industrial productivity and operability, an epoxy resin with excellent impact resistance in its cured form, a curable resin composition, and its cured form. A phenolic resin has a softening point of 60°C or higher and 120°C or lower, and is represented by the following formula (1). (In formula (1), there are multiple R...) 1 Each can be independently represented by a hydrogen atom, a hydrocarbon group having 1 to 4 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms. R 2 R indicates methyl. 3 Represents a hydrogen atom or a hydrocarbon group with 1 to 4 carbon atoms. Multiple m's exist, each independently an integer from 0 to 2, and p's exist, each an integer from 0 to 4. Multiple a's exist, each independently an integer of 1 or 2, with at least one a' being 1 and at least one a' being 2. n is the average of the repetitions, a real number where 1 < n < 15.

Description

Technical Field

[0001] This invention relates to a phenolic resin, an epoxy resin, a curable resin composition, and cured products formed by curing these, as well as 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 carbon fibers with epoxy resin and hardener as the matrix resin and then curing it, 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] Thermosetting resins such as epoxy resins, used as matrix resins in CFRP and other similar materials, are generally brittle. However, when applied to structural materials for aerospace or automotive applications, high mechanical strength is required. Methods for compensating for the low flexural strength, toughness, and adhesion of these thermosetting resins by adding high-toughness thermoplastic resins to the thermosetting resin matrix are widely known (Patent Documents 1-3). Specifically, the flexural strength or toughness of the prepreg is improved by combining particles of thermoplastic resins such as polyethersulfone, polyetherimide, or polyamide with the thermosetting resin matrix resin.

[0004] 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 further improvements in bending strength or toughness are required.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 60-243113

[0008] Patent Document 2: Japanese Patent Application Publication No. 09-100358

[0009] Patent Document 3: Japanese Patent Application Publication No. 2013-155330

[0010] Patent Document 4: Japanese Patent Application Publication No. 58-24531 Summary of the Invention

[0011] The problem that the invention aims to solve

[0012] Patent document 4 discloses 1,3-bis(2-(3,4-dihydroxyphenyl)-2-propyl)benzene, and shows that the compound is a crystal with a melting point of 133°C to 137°C. Since the synthesis of this compound requires recrystallization, many organic solvents or resins are discarded, posing a cost and environmental challenge when considering industrial production. Furthermore, to melt and mix the compound with other resins, heating to above 140°C is required, raising concerns about operability and high energy consumption.

[0013] The present invention was made in view of the above circumstances, and its object is to provide a phenolic resin with excellent industrial productivity and operability, an epoxy resin with excellent impact resistance of its cured form, a curable resin composition, and the cured form thereof.

[0014] Technical means to solve the problem

[0015] That is, the present invention is the content shown in [1] to

[10] below. In addition, in the present invention, "(value 1) to (value 2)" means including the upper limit value and the lower limit value. [1]

[0017] A phenolic resin having a softening point of 60°C or higher and 120°C or lower, and represented by the following formula (1).

[0018] [Chemistry 1]

[0019]

[0020] (In equation (1), there are multiple R) 1 Each can be independently represented by a hydrocarbon group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms. R 2 R indicates methyl. 3 This represents a hydrogen atom or a hydrocarbon group with 1 to 4 carbon atoms. Multiple 'm's exist, each independently an integer from 0 to 2, and 'p' is an integer from 0 to 4. Multiple 'a's exist, each independently an integer of 1 or 2, with at least one 'a' being 1 and at least one 'a' being 2. 'n' is the average of the repetitions, a real number where 1 < n < 15. [2]

[0022] A phenolic resin having a softening point of 60°C or higher and 120°C or lower, and represented by the following formula (3A).

[0023] [Chemistry 2]

[0024]

[0025] (In equation (3A), there are multiple R) 1 Each of the following groups independently represents a hydrocarbon group or an alkoxy group with 1 to 4 carbon atoms. Multiple occurrences of m are each an integer from 0 to 2. Multiple occurrences of a are each an integer of 1 or 2, with at least one a being 1 and at least one a being 2. n is the average of the repetitions, a real number where 1 < n < 15. [3]

[0027] A curable resin composition comprising the phenolic resin according to the preceding item [1] or [2]. [4]

[0029] A curable resin composition comprising a phenolic resin according to the preceding paragraph [1] or [2], and at least one selected from a curing accelerator, a polymerization initiator, an epoxy resin, an active ester compound, a phenolic resin other than the phenolic resin, a polyphenylene ether compound, a compound having vinyl unsaturated bonds, an isocyanate resin, a polyamide resin, a maleimide compound, a cyanate ester resin, a polyimide resin, polybutadiene and its modified forms, polystyrene and its modified forms, polyethylene and its modified forms, and a benzoxazine compound. [5]

[0031] An epoxy resin is obtained by reacting a phenolic resin according to the preceding paragraph [1] or [2] with a surface halo alcohol. [6]

[0033] The epoxy resin described in the preceding paragraph [5] has an epoxy equivalent of 190 g / eq. or more and 280 g / eq. or less. [7]

[0035] A curable resin composition comprising an epoxy resin and a curing agent as described in the preceding paragraph [5] or [6]. [8]

[0037] A curable resin composition comprising the epoxy resin according to the preceding paragraph [5] or [6] and at least one selected from the following: curing accelerator, polymerization initiator, epoxy resin other than the epoxy resin, active ester compound, phenolic resin, polyphenylene ether compound, compound having vinyl unsaturated bonds, isocyanate resin, polyamide resin, maleimide compound, cyanate ester resin, polyimide resin, polybutadiene and its modified forms, polystyrene and its modified forms, polyethylene and its modified forms, and benzoxazine compound. [9]

[0039] A hardened material, formed by hardening the hardening resin composition described in the preceding paragraph [7].

[10]

[0041] A carbon fiber reinforced composite material is formed by curing the curable resin composition described in the preceding paragraph [7].

[0042] The effects of the invention

[0043] This invention provides phenolic resins with excellent industrial productivity and operability, epoxy resins whose cured forms have excellent impact resistance, curable resin compositions, and their cured forms. Attached Figure Description

[0044] [ Figure 1 [] indicates the GPC diagram of the phenolic resin obtained in Synthesis Example 1.

[0045] [ Figure 2 [] indicates the GPC diagram of the epoxy resin obtained in Synthesis Example 2.

[0046] [ Figure 3 [] indicates the GPC diagram of the phenolic resin obtained in Synthesis Example 3.

[0047] [ Figure 4 [] indicates the GPC diagram of the epoxy resin obtained in Synthesis Example 4.

[0048] [ Figure 5 [] indicates the GPC diagram of the phenolic resin obtained in Synthesis Example 5.

[0049] [ Figure 6 [] indicates the GPC diagram of the epoxy resin obtained in Synthesis Example 6. Detailed Implementation

[0050] Hereinafter, embodiments of the present invention (hereinafter also referred to as "this embodiment") will be described in further detail.

[0051] The phenolic resin in this embodiment is represented by the following formula (1).

[0052] [Chemistry 3]

[0053]

[0054] In equation (1), there are multiple R 1 Each can be independently represented by a hydrocarbon group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms. R 2 R indicates methyl. 3 This represents a hydrogen atom or a hydrocarbon group with 1 to 4 carbon atoms. There are multiple m's, each an independent integer from 0 to 2, and p's integers from 0 to 4. n is the average of the repeated numbers, a real number where 1 < n < 15.

[0055] In formula (1), there are multiple 'a's that are independently integers of 1 or 2, and at least one of the multiple 'a's is 1 and at least one is 2. The ratio of 'a's of 1 (i.e., having one hydroxyl group) to 'a's of 2 (i.e., having two hydroxyl groups) is preferably 10:90 to 80:20. If the ratio of 'a's of 2 is 20% or more, the heat resistance becomes good; if it is 90% or less, the softening point becomes low and the operability becomes good. The ratio can be controlled by the mixing ratio of the raw material phenols and catechins, as described later.

[0056] In equation (1), the value of n can be calculated based on the number average molecular weight obtained 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.

[0057] The softening point of the phenolic resin in this embodiment is preferably 60°C or higher and 120°C or lower, and more preferably 60°C or higher and 100°C or lower. Because the softening point is within this range, the workability is excellent.

[0058] The hydroxyl equivalent of the phenolic resin in this embodiment is preferably 100 g / eq. to 140 g / eq., and more preferably 110 g / eq. to 130 g / eq.

[0059] The phenolic resin represented by formula (1) is preferably represented by formula (3) or formula (3A) below.

[0060] [Chemistry 4]

[0061]

[0062] In equations (3) and (3A), R 1 m, a, n represent the same meaning as in equation (1).

[0063] The phenolic resin of this embodiment can be mixed with the epoxy resin of this embodiment described later or various materials illustrated in this specification to be used as a curing resin composition.

[0064] Next, the reaction for obtaining the phenolic resin of this embodiment will be described.

[0065] The phenolic resin of this embodiment can be obtained, for example, by reacting phenols and catechols with disubstituted benzene compounds under acidic conditions. Examples of phenols include phenol, cresol, and xylenol. Examples of catechols include catechol, 3-methylcatechol, 4-methylcatechol, 4,5-dimethylcatechol, 3-tert-butylcatechol, 4-tert-butylcatechol, and 3,5-di-tert-butylcatechol; these can be used alone or in combination with two or more. Examples of disubstituted benzene compounds include α,α'-dihydroxy-1,3-diisopropylbenzene, α,α'-dihydroxy-1,4-diisopropylbenzene, 1,3-diisopropylbenzene, 1,4-diisopropylbenzene, 1,3-divinylbenzene, and 1,4-divinylbenzene; these can be used alone or in combination with two or more.

[0066] Examples of solvents include methanol, ethanol, propanol, isopropanol, toluene, xylene, methyl ethyl ketone, and methyl isobutyl ketone, but these are not limited to. Solvents can be used alone or in combination with two or more. When using a solvent, the amount of solvent used is preferably in the range of 5 to 500 parts by weight relative to 100 parts by weight of the catechol compound, and more preferably in the range of 10 to 300 parts by weight.

[0067] Examples of acidic catalysts include hydrochloric acid, phosphoric acid, sulfuric acid, formic acid, zinc chloride, ferric chloride, aluminum chloride, p-toluenesulfonic acid, methanesulfonic acid, activated clay, and ion exchange resins. These can be used alone or in combination of two or more. The amount of catalyst used is typically 0.1% to 50% by weight, preferably 1% to 30% by weight, relative to the catechol compound used. Too much catalyst will result in excessively high viscosity of the reaction solution, making stirring difficult; too little catalyst will slow down the reaction.

[0068] Next, the reaction for obtaining the epoxy resin of this embodiment will be described.

[0069] The epoxy resin in this embodiment is obtained by reacting the phenolic resin with an epihalohydrin. Epihalohydrin may include, for example, epichlorohydrin, β-methylepiochlorohydrin, epibromohydrin, etc. The amount of epihalohydrin used is preferably 1.0 mol to 20 mol relative to 1 mol of the hydroxyl group of the phenolic resin, more preferably 3.0 mol to 8.0 mol, and even more preferably 4.0 mol to 6.0 mol.

[0070] 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.

[0071] 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.

[0072] The reaction temperature is preferably 30℃ to 90℃, more preferably 35℃ to 80℃. 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 not preferred.

[0073] 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.

[0074] 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.

[0075] The representative structure of the epoxy resin in this embodiment is represented by the following formula (2).

[0076] [Chemistry 5]

[0077]

[0078] In equation (2), R 1 R2 R 3 , m, p, a, n represent the same meaning as in equation (1). R 4 It represents a hydrogen atom or a methyl group.

[0079] The epoxy resin of this embodiment preferably has a softening point of 100°C or less, and more preferably 80°C or less. With a softening point of 100°C or less, the workability is excellent. The lower limit of the softening point is preferably 40°C or more.

[0080] In this embodiment, the epoxy equivalent of the epoxy resin is preferably 190 g / eq. or more and 280 g / eq. or less, and more preferably 200 g / eq. or more and 240 g / eq. or less. When the epoxy equivalent is 280 g / eq. or less, the heat resistance becomes good, and when it is 190 g / eq. or more, the impact resistance becomes good.

[0081] The epoxy resin represented by formula (2) is preferably represented by formula (4) or formula (4A) below.

[0082] [Chemistry 6]

[0083]

[0084] In equations (4) and (4A), m, a, and n have the same meaning as in equation (1).

[0085] The curable resin composition of this embodiment preferably 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.

[0086] In the curable resin composition of this embodiment, an amine-based 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-based curing agent, 3,3'-diaminodiphenyl sulfone (3,3'-DDS), 4,4'-diaminodiphenyl sulfone (4,4'-DDS), and diaminodiphenylmethane (diaminodiphenyl) 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'-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 Diphenylmethane, 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 (DADPE), bisaniline, benzyl dimethylaniline, 2-(dimethylaminomethyl)phenol (DMP-10), 2,4,6-tris(dimethylaminomethyl)phenol (DMP-30), 2,4,6-tris(dimethylaminomethyl)phenol 2-ethylhexanoate, etc. Other examples include: aniline phenolic varnish, o-ethyl aniline 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 (such as 4,4'-bis(chloromethyl)-1,1'-biphenyl and 4,4'-bis(methoxymethyl)-1,1'-biphenyl) or substituted phenyls (such as 1,4-bis(chloromethyl)benzene, 1,4-bis(methoxymethyl)benzene and 1,4-bis(hydroxymethyl)benzene).

[0087] 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.

[0088] Examples of amide-based curing agents include dicyandiamide and polyamide resins synthesized from dimers of linolenic acid and ethylenediamine.

[0089] 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.); and 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.

[0090] 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.

[0091] 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.

[0092] 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.

[0093] 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 ethylene 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, 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.

[0094] Examples of active ester compounds include phenolic esters, thiophenolic esters, N-hydroxylamine esters, and esters of heterocyclic hydroxyl compounds.

[0095] 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).

[0096] 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.

[0097] 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.

[0098] 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.

[0099] 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.

[0100] 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.

[0101] 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.

[0102] 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.).

[0103] The curable resin composition of this embodiment can be obtained by uniformly mixing the components. The method for manufacturing the curable resin composition of this embodiment is not particularly limited; for example, it can be obtained by thoroughly mixing the curing agent, curing accelerator, inorganic filler, release agent, silane coupling agent, additives, etc., into the epoxy resin using an extruder, kneader, roller, planetary mixer, etc., until the mixture becomes homogeneous.

[0104] The obtained curable resin composition can be in various forms, such as resin sheets or prepregs, through its molding method. For example, a prepreg can be obtained by heating and melting the curable resin composition and / or resin sheets of this embodiment to reduce their viscosity and then impregnating them in a fiber substrate.

[0105] The curable resin composition of this embodiment can also be dissolved in solvents such as toluene, xylene, acetone, methyl ethyl ketone, methyl isobutyl ketone, dimethylformamide, dimethylacetamide, and N-methylpyrrolidone to prepare a varnish-like composition (hereinafter also simply referred to as varnish), and impregnated in substrates such as glass fiber, carbon fiber, polyester fiber, polyamide fiber, alumina fiber, and paper, and then heated and dried to prepare a prepreg. In this case, the solvent used in the mixture of the curable resin composition of this embodiment and the solvent accounts for 10% to 70% by weight, preferably 15% to 70% by weight.

[0106] After the prepreg is cut into the desired shape and stacked, pressure is applied to the stack using methods such as compression molding, autoclave molding, or sheet winding, while the curable resin composition is heated and cured, thereby obtaining carbon fiber reinforced plastic (CFRP). Alternatively, copper foil or organic film can be stacked during the stacking of the prepreg.

[0107] Regarding the molding method of CFRP, in addition to the method described above, it can also be obtained by using known methods. For example, the following resin transfer molding (RTM) method can also be used: a preform (a preform before resin impregnation) is made 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. Alternatively, 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 Publication No. 2005-527410 can be used. CAPRI involves venting the resin supply tank until the pressure drops below atmospheric pressure, using cyclic compression, and controlling the net forming pressure, thereby more appropriately controlling the resin injection process, particularly the VaRTM method. Furthermore, methods such as film stacking (using resin sheets (films) to sandwich fiber substrates) can also be used; methods to attach powdered resin to reinforced fiber substrates to improve impregnation; forming methods using flow layers or fluid slurry methods (powder impregnated yarn) during resin mixing in fiber substrates; and methods to weave resin fibers into fiber substrates.

[0108] 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.

[0109] The cured resin composition of this embodiment can be used for various purposes in addition to the aforementioned CFRP and other applications, such as: adhesives, coatings, coating agents, molding materials (including sheets, films, CFRP, etc.), sealants for semiconductor elements, sealants for liquid crystal display elements, sealants for organic electroluminescence (EL) elements, electrical / electronic parts such as printed wiring boards (ball grid array (BGA) substrates, build-up substrates, etc.) or three-dimensional (3D) printing, and additives to other resins, etc.

[0110] Examples of such adhesives include those used in civil engineering, construction, automotive, general office, and medical applications, as well as adhesives for electronic materials. Among these, adhesives for electronic materials include interlayer adhesives for multilayer substrates such as uplayer substrates, die bonding agents, underfills and other semiconductor adhesives, underfills for BGA reinforcement, mounting adhesives such as anisotropic conductive film (ACF) and anisotropic conductive paste (ACP), etc., and can be applied to a wide variety of applications.

[0111] When the curable resin composition of this embodiment is applied to a sealant for semiconductor devices, a lead frame including a semiconductor device and a semiconductor packaging substrate are placed in a mold. The curable resin composition of this embodiment is formed by melt casting, transfer molding, injection molding, compression molding, or the like. Then, it is heated at 80°C to 200°C for 2 to 10 hours to obtain a cured product. Examples of semiconductor devices manufactured using this sealant include: filling seals, impregnation seals, and transfer mold seals for capacitors, transistors, diodes, light-emitting diodes, ICs, large-scale integration circuits (LSIs), etc.; filling seals for ICs and LSIs such as chip onboard (COB), chip on film (COF), and tape automated bonding (TAB); underfills for flip chips; and seals (including reinforcing underfills) for mounting IC packages such as quad flat packages (QFPs), BGAs, and chip size packages (CSPs).

[0112] When applying the curable resin composition of this embodiment to printed wiring boards, a prepreg can be obtained by heating and melting it to reduce its viscosity and then impregnating it with reinforcing fibers such as glass fibers and polyamide fibers. Specific examples include glass fibers and / or organic fibers such as E-glass cloth, D-glass cloth, S-glass cloth, Q-glass cloth, spherical glass cloth, NE-glass cloth, and T-glass cloth, but these are not particularly limited. The shape of the substrate is not particularly limited; examples include woven fabric, non-woven fabric, roving, and woven felt. Furthermore, known weaving methods include plain weave, satin weave, and twill weave; these known weaving methods can be selected according to the target application or performance suitability. Additionally, woven fabric that has undergone fiber opening treatment or glass woven fabric that has undergone surface treatment using a silane coupling agent is preferably used. The thickness of the substrate is not particularly limited, but is preferably around 0.01 mm to 0.4 mm. Alternatively, a prepreg can be obtained by impregnating the varnish in reinforcing fibers and then heating and drying it, based on which a copper clad laminate (CCL) can be manufactured. A laminate using the curable resin composition of this embodiment can also be manufactured by hot pressing the obtained prepreg with a CCL. The laminate is not particularly limited as long as it includes one or more prepregs, and may have any other layers. Furthermore, by coating the varnish onto a release film, removing the solvent under heating, and performing a B-stage process, a sheet-like adhesive can be obtained. This sheet-like adhesive can be used as an interlayer insulating layer in multilayer substrates or as an adhesive sheet when mounting semiconductors. Additionally, the curable resin composition of this embodiment can also be preferably used for special substrate materials such as encapsulation substrates (substrates) or high-density interconnects (HDI).

[0113] The flexural strength of the curable resin composition of this embodiment is preferably 130 MPa or more, more preferably 140 MPa or more, and particularly preferably 150 MPa or more. The flexural modulus is preferably 3 GPa or more, more preferably 3.5 GPa or more, and particularly preferably 4 GPa or more. The IZOD impact strength is preferably 6 GPa or more, more preferably 7 GPa or more. These measurements are performed using the methods described in the examples described later.

[0114] Example

[0115] The following examples and embodiments are provided to further illustrate this implementation. 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 invention should not be limited by the specific examples shown below.

[0116] The various analytical methods used in the examples are described below.

[0117] The analytical methods are conducted under the following conditions.

[0118] Epoxy equivalent

[0119] The determination was performed using the method described in Japanese Industrial Standards (JIS) K-7236, and the unit is g / eq.

[0120] GPC (Gel Permeation Chromatography)

[0121] Manufacturer: Waters

[0122] Tubing Strings: Protective tubing strings SHODEX GPC KF-401HQ, KF-402HQ, KF-402.5HQ, KF-403HQ,

[0123] Flow rate: 0.3 ml / min.

[0124] Column temperature: 40℃

[0125] Solvent used: THF (tetrahydrofuran)

[0126] Detector: RI (Differential Refraction Detector)

[0127] [Synthesis example 1]

[0128] 83 parts by weight of catechol, 71 parts by weight of phenol, 97 parts by weight of α,α'-dihydroxy-1,3-diisopropylbenzene, 400 parts by weight of toluene, and 3 parts by weight of p-toluenesulfonic acid monohydrate were added to a flask including a stirrer, reflux cooling tube, and stirring device, and stirred to dissolve and react the substances while heating to 110°C. After reaching 110°C, the reaction was allowed to proceed for 4 hours. During heating and reaction, the distilled water was removed from the system. Subsequently, the mixture was cooled to 80°C, 100 parts by weight of water was added, and 1 part by weight of sodium tripolyphosphate was added for neutralization. Repeated washing with water was performed to remove salt and unreacted catechol. Then, toluene was removed by distillation under heating and reduced pressure to obtain 110 parts by weight of the phenolic resin represented by formula (1). The hydroxyl equivalent was 120 g / eq., and the softening point was 78°C. The GPC diagram of the obtained phenolic resin is shown in Figure 1. Figure 1 .

[0129] [Synthesis example 2]

[0130] Relative to 91 parts by weight of the phenolic resin obtained in Synthesis Example 1, 444 parts by weight of epichlorohydrin (ECH, hereinafter the same) and 8 parts by weight of benzyltrimethylammonium chloride (BTMAC, hereinafter the same) were added to a reaction vessel. After heating, stirring, and dissolving, the reaction was carried out for 6 hours while maintaining the temperature at 50°C. Then, 5 parts by weight of water were added, and 31 parts by weight of flake sodium hydroxide were added in portions over 2 hours at 50°C. The reaction was then carried out further at 50°C for 1.5 hours, followed by a further reaction at 70°C for 30 minutes. After repeated washing with water to remove byproduct salts, excess epichlorohydrin was distilled off from the oil layer under heating and reduced pressure. 272 ​​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 8 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 120 parts by weight of the epoxy resin represented by formula (2). The obtained epoxy resin has an epoxy equivalent of 200 g / eq. and a softening point of 50°C. The GPC diagram of the obtained epoxy resin is shown in [the diagram]. Figure 2 .

[0131] [Synthesis example 3]

[0132] A flask containing a stirrer, reflux condenser, and stirring apparatus was loaded with 165 parts by weight of catechol, 97 parts by weight of α,α'-dihydroxy-1,3-diisopropylbenzene, 400 parts by weight of toluene, and 3 parts by weight of p-toluenesulfonic acid monohydrate, and stirred. The mixture was heated to 110°C to dissolve and react the catechol. The reaction was allowed to proceed for 4 hours after reaching 110°C. Water distilled off the system during heating and reaction was removed. The mixture was then cooled to 80°C, and 100 parts by weight of water and 1 part by weight of sodium tripolyphosphate were added for neutralization. Repeated washing with water was performed to remove salts and unreacted catechol. Toluene was then removed by distillation under reduced pressure to obtain 140 parts by weight of phenolic resin. The hydroxyl equivalent was 114 g / eq, and the softening point was 83°C. The GPC diagram of the obtained phenolic resin is shown below. Figure 3 .

[0133] [Synthesis Example 4]

[0134] Compared to 91 parts by weight of the phenolic resin obtained in Synthesis Example 3, 444 parts by weight of epichlorohydrin (ECH, hereinafter the same) and 8 parts by weight of benzyltrimethylammonium chloride (BTMAC, hereinafter the same) were added to a reaction vessel. After heating, stirring, and dissolving, the reaction was carried out at 50°C for 6 hours. Then, 5 parts by weight of water were added, and 34 parts by weight of flake sodium hydroxide were added in portions over 2 hours at 50°C. The reaction was then carried out for another 1.5 hours at 50°C and another 30 minutes at 70°C. After repeated washing with water to remove byproduct salts, excess epichlorohydrin was distilled off from the oil layer under heating and reduced pressure. 272 ​​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 8 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 130 parts by weight of epoxy resin. The obtained epoxy resin had an epoxy equivalent of 208 g / eq. and a softening point of 53℃. The GPC diagram of the obtained epoxy resin is shown in [the diagram]. Figure 4 .

[0135] [Synthesis example 5]

[0136] 83 parts by weight of catechol, 81 parts by weight of p-cresol, 97 parts by weight of α,α'-dihydroxy-1,3-diisopropylbenzene, 400 parts by weight of toluene, and 3 parts by weight of p-toluenesulfonic acid monohydrate were added to a flask including a stirrer, reflux cooling tube, and stirring device, and the mixture was stirred to dissolve and react while being heated to 110°C. After reaching 110°C, the mixture was allowed to react for 4 hours. During heating and reaction, the distilled water was removed from the system. Then, the mixture was cooled to 80°C, 100 parts by weight of water was added, and 1 part by weight of sodium tripolyphosphate was added for neutralization. The mixture was washed repeatedly with water to remove salt and unreacted catechol. Then, toluene was distilled off under heating and reduced pressure to obtain 115 parts by weight of the phenolic resin represented by formula (1). The hydroxyl equivalent was 130 g / eq., and the softening point was 90°C. The GPC diagram of the obtained phenolic resin is shown in Figure 1. Figure 5 .

[0137] [Synthesis example 6]

[0138] Compared to the 78 parts by weight of phenolic resin obtained in Synthesis Example 5, 333 parts by weight of epichlorohydrin (ECH, hereinafter the same) and 7 parts by weight of benzyltrimethylammonium chloride (BTMAC, hereinafter the same) were added to a reaction vessel. After heating, stirring, and dissolving, the reaction was carried out for 6 hours while maintaining the temperature at 50°C. Then, 4 parts by weight of water were added, and 26 parts by weight of flake sodium hydroxide were added in portions over 2 hours at 50°C. The reaction was then carried out for another 1.5 hours at 50°C, followed by a further 30 minutes at 70°C. After repeated washing with water to remove byproduct salts, excess epichlorohydrin was distilled off from the oil layer under heating and reduced pressure. 223 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 8 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 100 parts by weight of the epoxy resin represented by formula (2). The obtained epoxy resin had an epoxy equivalent of 234 g / eq. and a softening point of 62°C. The GPC diagram of the obtained epoxy resin is shown in [the diagram]. Figure 6 .

[0139] [Examples 1-2, Comparative Examples 1-2]

[0140] The epoxy resins obtained in Synthesis Example 2, Synthesis Example 4, and Synthesis Example 6 were mixed according to the proportions (parts by weight) in Table 1, and 4,4'-diaminodiphenyl sulfone (DDS) was used as a curing agent. The mixtures were then cured at 180°C for 6 hours to produce cured products. Similarly, as Comparative Example 2, epoxy resin ESPD295 (manufactured by Sumitomo Chemical Co., Ltd., with an epoxy equivalent of 298 g / eq. and a softening point of 68°C) represented by the following formula (5) was mixed with DDS to prepare cured products. The physical properties were then evaluated. The results are described in Table 1.

[0141] [Chemistry 7]

[0142]

[0143] The determination of physical properties shall be carried out under the following conditions.

[0144] <Bending strength, bending elastic modulus, and test conditions>

[0145] The measurements were performed in accordance with JIS K-7074.

[0146] <IZOD Impact Test Conditions>

[0147] The measurements were performed in accordance with JIS K-6911.

[0148] [Table 1]

[0149]

[0150] Based on the results in Table 1, it was confirmed that the target values ​​for various mechanical properties were achieved in Examples 1 and 2 using the epoxy resin of this application, especially the excellent impact resistance (IZOD test strength).

Claims

1. A phenolic resin having a softening point of 60°C or higher and 120°C or lower, and represented by the following formula (1). [Chemistry 1] (In equation (1), there are multiple R) 1 Each can be independently represented by a hydrocarbon group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms. R 2 R indicates methyl. 3 Represents a hydrogen atom or a hydrocarbon group with 1 to 4 carbon atoms. Multiple m's exist, each independently an integer from 0 to 2, and p's exist, each an integer from 0 to 4. Multiple a's exist, each independently an integer of 1 or 2, with at least one a' being 1 and at least one a' being 2. n is the average of the repetitions, a real number where 1 < n < 15.

2. A phenolic resin having a softening point of 60°C or higher and 120°C or lower, and represented by the following formula (3A). [Chemistry 2] (In equation (3A), there are multiple R) 1 Each of the following groups independently represents a hydrocarbon group or an alkoxy group with 1 to 4 carbon atoms. Multiple occurrences of m are each an integer from 0 to 2. Multiple occurrences of a are each an integer of 1 or 2, with at least one a being 1 and at least one a being 2. n is the average of the repetitions, a real number where 1 < n < 15.

3. A curable resin composition comprising the phenolic resin as described in claim 1 or 2.

4. A curable resin composition comprising a phenolic resin as described in claim 1 or 2, and at least one selected from a curing accelerator, a polymerization initiator, an epoxy resin, an active ester compound, a phenolic resin other than the phenolic resin, a polyphenylene ether compound, a compound having vinyl unsaturated bonds, an isocyanate resin, a polyamide resin, a maleimide compound, a cyanate ester resin, a polyimide resin, polybutadiene and its modified forms, polystyrene and its modified forms, polyethylene and its modified forms, and a benzoxazine compound.

5. An epoxy resin obtained by reacting the phenolic resin as described in claim 1 or 2 with a surface haloalcohol.

6. The epoxy resin according to claim 5, wherein the epoxy equivalent is 190 g / eq. or more and 280 g / eq. or less.

7. A curable resin composition comprising the epoxy resin and curing agent as described in claim 5.

8. A curable resin composition comprising the epoxy resin as described in claim 5 and at least one selected from the group consisting of a curing accelerator, a polymerization initiator, an epoxy resin other than said epoxy resin, an active ester compound, a phenolic resin, a polyphenylene ether compound, a compound having vinyl unsaturated bonds, an isocyanate resin, a polyamide resin, a maleimide compound, a cyanate ester resin, a polyimide resin, polybutadiene and its modified forms, polystyrene and its modified forms, polyethylene and its modified forms, and a benzoxazine compound.

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

10. A carbon fiber reinforced composite material, formed by curing the curable resin composition as described in claim 7.

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