Method for producing metal phenoxide, method for producing epoxy resin, and method for producing cured epoxy resin.

Abstract

To provide a method for efficiently obtaining metal phenoxide from decomposition products of thermosetting resins, which contain a variety of substances in addition to the thermosetting resin, such as epoxy resin.SOLUTION: A method for producing metal phenoxide includes following steps A-C. Step A: decomposing a thermosetting cured resin to produce a decomposition liquid A containing metal phenoxide. Step B: adding water to the decomposition liquid A obtained in the step A, to produce an oil-water two-phase liquid B. Step C: separating the oil-water two-phase liquid B obtained in the step B to oil and water, thereby recovering metal phenoxide.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a method for producing a metal phenoxide, a method for producing an epoxy resin, and a method for producing a cured product of an epoxy resin.

Background Art

[0002] Thermosetting resins such as epoxy resins generally provide cured products with excellent mechanical properties and heat resistance by curing under various formulations and curing conditions. Therefore, thermosetting resins are used in a wide range of fields such as adhesives, paints, FRP, electrical and electronic materials, etc.

[0003] On the other hand, due to their excellent mechanical properties, it is difficult to process thermosetting resins after curing, and it is difficult to remove only the thermosetting resin from the products of their applications after the cured products are used in various applications. In particular, it is difficult to physically remove the thermosetting resin from a cured product obtained by curing the thermosetting resin in contact with a metal, inorganic fiber, etc.

[0004] Under such circumstances, as a method for removing an epoxy resin from a cured epoxy resin product, in Citation Document 1, a method for decomposing, dissolving, and recovering a cured epoxy resin product using an organic solvent and an alkali metal catalyst is disclosed, and further, a method for producing an epoxy resin by reacting the obtained epoxy resin decomposition product with an epoxy resin has been proposed.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, the method disclosed in Patent Document 1 does not selectively recover epoxy resin from epoxy resin decomposition products, and instead reacts the epoxy resin with various other products to produce epoxy resin. As a result, the epoxy equivalent of the obtained epoxy resin is very low, and it cannot be said that this is a technology with a high epoxy resin yield (recovery rate).

[0007] The object of this invention is to provide a method for efficiently obtaining metal phenoxides from thermosetting resin decomposition products that contain various products in addition to thermosetting resins such as epoxy resins. [Means for solving the problem]

[0008] The inventors of the present invention conducted research to solve the above problems and found that a metal phenoxide can be obtained by adding water to the decomposition solution of a thermosetting resin and separating the oil and water. They then confirmed that epoxy resin can be synthesized again from the metal phenoxide obtained in this process, thus completing the invention.

[0009] In other words, the gist of the present invention may include the following [1] to [9]. [1] A method for producing a metal phenoxide, comprising the following steps A to C. Step A: A step to decompose a thermosetting resin cured product and obtain a decomposition solution A containing metal phenoxide. Step B: A step in which water is added to the decomposition liquid A obtained in Step A to obtain an oil-water two-phase liquid B. Step C: A step to separate the oil-water two-phase liquid B obtained in Step B to obtain a metal phenoxide. [2] The above step C includes the following steps D to E for the production of the metal phenoxide described in [1] Construction method. Step D: The oil-water two-phase liquid B obtained in Step B is separated into oil-water phases, and the resulting aqueous phase C is mixed with an organic solvent to obtain suspension D. Step E: A step of solid-liquid separation of the suspension D obtained in step D to obtain a metal phenoxide from the solid phase [3] Step B is a step of solid-liquid separation of the decomposition liquid A obtained in step A to remove insoluble matter to obtain a decomposition liquid A', and to obtain an oil-water two-phase liquid B by adding water to the decomposition liquid A', the method for producing a metal phenoxide according to [1] or [2]. [4] A method for producing a metal phenoxide according to any one of [1] to [3], wherein the metal phenoxide is a metal alkoxide of a bisphenol compound. [5] The method for producing a metal phenoxide according to [4], wherein the bisphenol compound of the metal alkoxide of the bisphenol compound is 2,2-bis(4-hydroxyphenyl)propane. [6] The method for producing a metal phenoxide according to [1] to [5], wherein the metal of the metal phenoxide is an alkali metal. A method for producing epoxy resin, comprising the step of reacting a metal phenoxide obtained by any of the manufacturing methods described in [7][1] to [6] with an epihalohydrin. A method for producing epoxy resin, comprising the step of reacting an epoxy resin obtained by the manufacturing method described in [8][7] with a polyvalent hydroxy compound. A method for producing an epoxy resin cured product, comprising the step of curing an epoxy resin composition containing an epoxy resin and a curing agent obtained by the manufacturing method described in [9], [7], or [8]. [Effects of the Invention]

[0010] The present invention provides a method for efficiently obtaining metal phenoxides from thermosetting resin decomposition products containing various products in addition to thermosetting resins such as epoxy resins. Furthermore, epoxy resins can be produced by reacting the obtained metal phenoxides with epihalohydrins. [Modes for carrying out the invention]

[0011] Embodiments of the present invention will be described in detail below, but the present invention is not limited to the following description and can be modified and implemented as appropriate without departing from the spirit of the invention. In this specification, when "~" is used to enclose numerical values ​​or physical properties, it is intended to include the values ​​before and after it.

[0012] <1. Method for producing metal phenoxides> A first embodiment of the present invention is a method for producing a metal phenoxide, comprising the following steps A to C. Step A: A step to decompose a thermosetting resin cured product and obtain a decomposition solution A containing metal phenoxide. Step B: A step in which water is added to the decomposition liquid A obtained in Step A to obtain an oil-water two-phase liquid B. Step C: A step to separate the oil-water two-phase liquid B obtained in Step B to obtain a metal phenoxide.

[0013] <1-1. Metal Phenoxides> The metal phenoxide produced in this embodiment is a metal alkoxide of a phenol compound. This phenol compound is a compound derived from a monomer of a thermosetting resin, a curing agent, and a terminal encapsulant. The metal phenoxide may be a metal alkoxide of a single phenol compound, or a mixture of metal alkoxides of two or more phenol compounds. Furthermore, the metal of the metal phenoxide may be a single metal, or a combination of two or more metals.

[0014] Examples of phenol compounds include phenol, o-cresol, m-cresol, p-cresol, p-ethylphenol, p-isopropylphenol, and p-tert-butylphenol. Phenol, p-cumylphenol, p-cyclohexylphenol, p-octylphenol, p-nonylphenol, 2,4-xylenol, p-methoxyphenol, p-hexyloxyphenol, p-decyloxyphenol, o-chlorophenol, m-chlorophenol, p-chlorophenol, p-bromophenol, pentabromophenol, pentachlorophenol, p-phenylphenol, p-isopropenylphenol, 2,4-di(1'-methyl-1'-phenylethyl)phenol, β Monovalent phenol compounds such as naphthol, α-naphthol, p-(2',4',4'-trimethylchromanyl)phenol, and 2-(4'-methoxyphenyl)-2-(4''-hydroxyphenyl)propane; divalent phenol compounds such as hydroquinone, resorcinol, and 2-methylresorcinol; 2,2'-biphenol, 4,4'-biphenol, 1,5-naphthalenediol, 2,7-naphthalenediol, bis(4-hydroxyphenyl)methane (i.e., bisphenol F), bis{(4 2,2-Bis(4-hydroxyphenyl)phenyl}methane, 1,1-bis(4-hydroxyphenyl)ethane (i.e., bisphenol E), 1,1-bis(4-hydroxyphenyl)-1-phenylethane (i.e., bisphenol AP), 2,2-bis(4-hydroxyphenyl)hexafluoropropane (i.e., bisphenol AF), 2,2-bis(4-hydroxyphenyl)propane (i.e., bisphenol A), 2,2-bis{(4-hydroxy-3-methyl)phenyl}propane, 2,2-Bi (4-hydroxy-3,5-dimethyl)phenyl)propane, 2,2-bis{(3,5-dibromo-4-hydroxy)phenyl}propane, 2,2-bis{(3-isopropyl-4-hydroxy)phenyl}propane, 2,2-bis{(4-hydroxy-3-phenyl)phenyl}propane, 2-(4-hydroxyphenyl)-2-(3-carboxy-4-hydroxyphenyl)propane, 2-(2-hydroxyphenyl)-2-(4-hydroxyphenyl)propane, 1-(4-hydroxyphenyl)-1,3,3-trimethyl-5-hydroxyindan, 2-(4-hydroxyphenyl)-[3-{2-(4-hydroxyphenyl)propane-2-yl}-4-hydroxyphenyl]propane, 2,2-bis(4-hydroxyphenyl)butane (i.e., bisphenol B), 1,1-bis(4-hydroxyphenyl)-1,1-diphenylmethane (i.e., bisphenol BP), 4,4′-isopropylidenebis(2-methylphenol) (i.e., bisphenol C), 2,2 -Bis(4-hydroxy-3-isopropylphenyl)propane (i.e., bisphenol G), 2,2-bis(4-hydroxyphenyl)-3-methylbutane, 2,2-bis(4-hydroxyphenyl)-3,3-dimethylbutane, 2,4-bis(4-hydroxyphenyl)-2-methylbutane, 2,2-bis(4-hydroxyphenyl)pentane, 2,2-bis(4-hydroxyphenyl)-4-methylpentane, 1,1-bis(4-hydroxyphenyl)cyclohexane, 1, 1-Bis(4-hydroxyphenyl)-4-isopropylcyclohexane, 1,1-Bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane, 9,9-Bis(4-hydroxyphenyl)fluorene, 9,9-Bis{(4-hydroxy-3-methyl)phenyl}fluorene, α,α'-Bis(4-hydroxyphenyl)-o-diisopropylbenzene, α,α'-Bis(4-hydroxyphenyl)-m-diisopropylbenzene, α,α'-Bis(4-hydroxyphenyl) Examples include bisphenol compounds such as (nyl)-p-diisopropylbenzene, 1,3-bis(4-hydroxyphenyl)-5,7-dimethyladamantane, 4,4'-dihydroxydiphenyl sulfone (i.e., bisphenol S), 4,4'-dihydroxydiphenyl sulfoxide, 4,4'-dihydroxydiphenyl sulfide, 4,4'-dihydroxydiphenyl ketone, 4,4'-dihydroxydiphenyl ether, and 4,4'-dihydroxydiphenyl ester; and others.

[0015] Among these, the phenolic compound is preferably a bisphenol compound, and more preferably selected from 2,2-bis(4-hydroxyphenyl)propane, 1,1-bis(4-hydroxyphenyl)-1-phenylethane, 2,2-bis(4-hydroxyphenyl)hexafluoropropane, 2,2-bis(4-hydroxyphenyl)butane, 1,1-bis(4-hydroxyphenyl)-1,1-diphenylmethane, 4,4'-isopropylidene bis(2-methyl-phenol), 1,1-bis(4-hydroxyphenyl)ethane, bis(4-hydroxyphenyl)methane, 2,2-bis(4-hydroxy-3-isopropylphenyl), and 4,4'-dihydroxydiphenyl sulfone, and even more preferably 2,2-bis(4-hydroxyphenyl)propane. Among these, the phenolic compound is more preferably selected from 2,2-bis(4-hydroxyphenyl)propane, 1,1-bis(4-hydroxyphenyl)-1-phenylethane, 2,2-bis(4-hydroxyphenyl)hexafluoropropane, 2,2-bis(4-hydroxyphenyl)butane, 1,1-bis(4-hydroxyphenyl)-1,1-diphenylmethane, 4,4'-isopropylidene bis(2-methyl-phenol), 1,1-bis(4-hydroxyphenyl)ethane, bis(4-hydroxyphenyl)methane, 2,2-bis(4-hydroxy-3-isopropylphenyl), and 4,4'-dihydroxydiphenyl sulfone, and even more preferably 2,2-bis(4-hydroxyphenyl)propane.

[0016] The metal of the metal alkoxide of the phenolic compound is not particularly limited, and examples thereof include alkali metals such as lithium, sodium, and potassium; magnesium; and aluminum; etc. Among them, an alkali metal is preferable, more preferably selected from sodium and potassium, and even more preferably sodium.

[0017] Therefore, the metal phenoxide produced in this embodiment is preferably a metal alkoxide of a bisphenol compound, more preferably a sodium alkoxide of a bisphenol compound, and even more preferably a disodium alkoxide of 2,2-bis(4-hydroxyphenyl)propane.

[0018] Hereinafter, the metal phenoxide may be expressed as "phenolic compound·M (M is a metal)". Specifically, for example, the sodium alkoxide of bisphenol A may be expressed as "bisphenol A·2Na" according to the above notation.

[0019] In this embodiment, the metal phenoxide can be handled stably by the addition of water molecules. When the added water is removed by distillation, the metal phenoxide decomposes, so the phenol content in the metal phenoxide is preferably 80% by mass or less, more preferably 70% by mass or less, and even more preferably 60% by mass or less.

[0020] <1-2. Process A> Step A is a step in which a thermosetting resin cured product is decomposed to obtain a decomposition solution A containing a metal phenoxide.

[0021] (Thermosetting resin cured product) The thermosetting resin cured product that is decomposed in process A is obtained by curing the thermosetting resin either without using a curing agent or with a curing agent.

[0022] The thermosetting resin used in the thermosetting resin cured product is not particularly limited and includes copolymers of the phenol compound and other monomers mentioned above, homopolymers of the epoxidized phenol compound mentioned above, and copolymers of the epoxidized phenol compound and other monomers mentioned above. Examples of such thermosetting resins include epoxy resins and phenol resins. Among thermosetting resins, epoxy resins are resins that have epoxy groups as constituent elements, and phenol resins are resins that have phenol, an aromatic compound, as a constituent element. The thermosetting resin cured product may be a cured product of one type of thermosetting resin, or it may be a cured product of two or more types of thermosetting resins.

[0023] The epoxy resin is not particularly limited and includes, for example, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, alicyclic epoxy resin, aliphatic chain epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin, bisphenol A novolac type epoxy resin, diglycidyl ether of biphenol, diglycidyl ether of naphthalenediol, diglycidyl ether of phenol compounds, diglycidyl ether of alcohol compounds, alkyl substituted derivatives thereof, halogenated derivatives thereof, and hydrogenated derivatives thereof. Poxy resin may be used alone or in combination of two or more types.

[0024] Examples of curing agents for thermosetting resins include acid anhydrides, amine compounds, phenol compounds, and isocyanate compounds. The curing agent may be used alone or in combination of two or more types.

[0025] Furthermore, the curing accelerator used when curing thermosetting resins is not particularly limited and includes alkali metal compounds, imidazole compounds, tertiary amine compounds, quaternary ammonium salts, organophosphorus compounds, etc. The curing accelerator may be used alone or in combination of two or more types.

[0026] The thermosetting resin cured product may be mixed with other components to form a composite material, to the extent that it does not impair the effects of the present invention. Examples of other components include inorganic substances such as carbon, glass, metals, and metal compounds; thermoplastic resins such as polyethylene and polypropylene; and so on. Examples of inorganic substances in shape include fibers, particles, and foils. The fibers may be nonwoven or woven fabrics. In the case of woven fabrics, they may be cloth materials made by weaving fiber bundles, or UD (Uni-Direction) materials in which fiber bundles are arranged in one direction. The inorganic substance may consist of one type alone or two or more types.

[0027] (Disassembly method) As a method for decomposing thermosetting resin cured products, any known decomposition method for thermosetting resin cured products or a decomposition method similar to a known decomposition method that can generate metal phenoxides can be appropriately employed. As a known method, for example, a method of contacting the thermosetting resin cured product with a treatment solution containing a decomposition catalyst and an organic solvent is preferred.

[0028] The decomposition catalyst contained in the processing solution is not particularly limited, as long as it can decompose the thermosetting resin cured product to produce a metal phenoxide. Examples of decomposition catalysts include metal hydrides, hydroxides, borohydrides, amide compounds, fluorides, chlorides, bromides, iodides, borates, phosphates, carbonates, sulfates, nitrates, organic acid salts, and alkoxides. The metal contained in the decomposition catalyst is the same metal as the metal phenoxide intended for production, i.e., alkali metals such as lithium, sodium, and potassium; magnesium; and aluminum; and is preferably an alkali metal, and more preferably sodium. The decomposition catalyst may be used alone or in combination of two or more types.

[0029] Among the above compounds, the decomposition catalyst is preferably a metal alkoxide, from the viewpoint of suppressing corrosion of the reaction vessel, thinning of the reaction vessel, and contamination of the product caused by the corrosion of the reaction vessel. A metal alkoxide is a compound in which the hydrogen atoms of the hydroxyl group of an alcohol are replaced with a metal, and can be obtained by adding a metal to an alcohol.

[0030] The alcohol used to obtain the metal alkoxide is not particularly limited and includes methanol, ethanol, 1-butanol, 2-butanol, 2-methyl-1-propanol, 2-methyl-2-propanol, 1-pentanol, 2-pentanol, 3-pentanol, 2-methyl-1-butanol, 2-methyl-2-butanol, 3-methyl-1-butanol, 3-methyl-2-butanol, 2,2-dimethyl-1-propanol, 1-hexanol, 2-hexanol, 3-hexanol 2-methyl-1-pentanol, 4-methyl-2-pentanol, 2-ethyl-1-butanol, 1-heptanol, 2-heptanol, 3-heptanol, 2-ethylhexanol, dodecanol, cyclohexanol, 1-methylcyclohexanol, 2-methylcyclohexanol, 3-methylcyclohexanol, 4-methylcyclohexanol, benzyl alcohol, phenoxyethanol, 1-(2-hydroxyethyl)-2-pyrrolidone, diacetone alcohol, ethanol Examples include ethylene glycol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, diethylene glycol, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monopropyl ether, diethylene glycol monobutyl ether, triethylene glycol, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, tetraethylene glycol, polyethylene glycol (molecular weight 200-400), 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 1,5-pentanediol, glycerin, and dipropylene glycol. These alcohols may be used individually or in combination of two or more.

[0031] The metal alkoxide may be in a solid or solution state. From the viewpoint of the decomposition efficiency of the thermosetting resin cured product, it is preferable to select the metal alkoxide from sodium methoxide, sodium ethoxide, sodium propoxide, sodium isopropoxide, sodium benzyl alkoxide (sodium benzyl oxide), potassium methoxide, potassium ethoxide, potassium propoxide, isopropoxide, and potassium benzyl alkoxide (potassium benzyl oxide).

[0032] These alkali metal alkoxides may be used individually or in combination of two or more.

[0033] The organic solvent is not particularly limited and includes alcohol-based solvents, ether-based solvents, and aromatic solvents.

[0034] The alcoholic solvent is not particularly limited and includes 1-butanol, 2-butanol, 2-methyl-1-propanol, 2-methyl-2-propanol, 1-pentanol, 2-pentanol, 3-pentanol, 2-methyl-1-butanol, 2-methyl-2-butanol, 3-methyl-1-butanol, 3-methyl-2-butanol, 2,2-dimethyl-1-propanol, 1-hexanol, 2-hexanol, 3-hexanol, 2-methyl-1-pentanol, 4-methyl-2-pentanol, 2-ethyl-1-butanol, 1-heptanol, 2-heptanol, 3-heptanol, 2-ethylhexanol, dodecanol, cyclohexanol, 1-methylcyclohexanol, 2-methylcyclohexanol, 3-methylcyclohexanol, 4-methylcyclohexanol, benzyl alcohol, and phenoxyethanol. Alcohol-based solvents may be used individually or in combination of two or more.

[0035] The ether solvent is not particularly limited and includes diethyl ether, dipropyl ether, dibutyl ether, butyl methyl ether, butyl ethyl ether, diisoamyl ether, hexyl methyl ether, octyl methyl ether, cyclopentyl methyl ether, and dicyclopentyl ether. The ether solvent may be used alone or in combination of two or more types.

[0036] Aromatic solvents are not particularly limited and include alkylbenzenes such as benzene, toluene, xylene, trimethylbenzene, and ethylbenzene, and alkylnaphthalenes such as methylnaphthalene, ethylnaphthalene, and dimethylnaphthalene. Aromatic solvents may be used individually or in combination of two or more.

[0037] Furthermore, one or more alcohol-based solvents and one or more ether-based solvents may be used in combination, or one or more alcohol-based solvents and one or more aromatic solvents may be used. These may be used in combination, or one or more ether-based solvents may be used in combination with one or more aromatic solvents, or one or more alcohol-based solvents may be used in combination with one or more ether-based solvents and one or more aromatic solvents.

[0038] Of these, alcohol-based solvents are preferred because they exhibit excellent solubility of decomposition products of thermosetting resin cured products. Furthermore, when a metal alkoxide is used as a decomposition catalyst, it is preferable that at least a portion of the organic solvent contains the same alcohol-based solvent as the raw material alcohol for the metal alkoxide.

[0039] Furthermore, from the viewpoint of requiring heating in the decomposition of the thermosetting resin cured product, the organic solvent is preferably an organic solvent with a boiling point of 100°C or higher at atmospheric pressure, more preferably 120°C or higher, and particularly preferably 150°C or higher. From this perspective as well, benzyl alcohol (boiling point 205°C) is a preferred organic solvent.

[0040] The processing solution may further contain other components besides the decomposition catalyst and organic solvent, as needed. Examples of other components include surfactants and low-viscosity solvents.

[0041] From the viewpoint of improving the decomposition efficiency of thermosetting resin curing products, the concentration of the decomposition catalyst in the treatment solution is preferably 0.001 mol / L or more and 100 mol / L or less, more preferably 0.005 mol / L or more and 50 mol / L or less, and even more preferably 0.01 mol / L or more and 20 mol / L or less. The higher the concentration of the decomposition catalyst, the more efficiently the thermosetting resin curing product can be decomposed. The lower the concentration of the decomposition catalyst, the more efficiently the thermosetting resin curing product can be decomposed without increasing the viscosity of the treatment solution.

[0042] When preparing the treatment solution, the decomposition catalyst may be mixed with the organic solvent in a solid state or in a solution state. Heating is not required when preparing the treatment solution; it can be prepared by mixing the organic solvent and the decomposition catalyst at room temperature (approximately 5-35°C).

[0043] The reaction vessel used when bringing the processing liquid into contact with the thermosetting resin cured product is preferably a stainless steel vessel from the viewpoint of corrosion prevention. The stainless steel is not particularly limited, but examples include austenitic stainless steel, ferritic stainless steel, martensitic stainless steel, austenitic-ferritic stainless steel, and precipitation-hardening stainless steel, and is preferably austenitic stainless steel, and particularly preferably SUS304, SUS316, or SUS316L.

[0044] The reaction vessel is not particularly limited as long as it is possible to bring the processing liquid and the thermosetting resin cured product into contact. Any container that can be used as a decomposition tank may be box-shaped, cylindrical, mesh cage-shaped, or made of a porous material. The ratio of the volume of the thermosetting resin cured material placed in the container to the volume of the container (filling rate) is preferably in the range of 5% to 25% from the viewpoint of dissolution efficiency.

[0045] When the treatment solution is brought into contact with the thermosetting resin cured product, the heating temperature of the treatment solution is preferably 100°C or higher, more preferably 130°C or higher, and particularly preferably 150°C or higher, from the viewpoint of improving the decomposition efficiency of the thermosetting resin cured product. On the other hand, from the viewpoint of suppressing the denaturation of the solvent and decomposition products, this temperature is preferably 300°C or lower, and particularly preferably 250°C or lower.

[0046] The contact time between the processing solution and the thermosetting resin cured product is such that the thermosetting resin cured product is sufficiently decomposed. The time required for dissolution is sufficient and varies depending on the type of thermosetting resin, the type and concentration of the decomposition catalyst and organic solvent used, and the processing temperature, but typically 50% or more by weight of the cured thermosetting resin can be decomposed and dissolved in about 2 to 50 hours.

[0047] <1-3. Process B> Step B is a step in which water is added to the decomposition liquid A obtained in step A to obtain an oil-water two-phase liquid B. In this step, the metal phenoxide contained in decomposition liquid A is selectively extracted into the aqueous phase. On the other hand, decomposition products of the thermosetting resin curing product other than metal phenoxide are insoluble or sparingly soluble in water, and therefore most of them remain in the oil phase (i.e., organic phase). Therefore, according to the manufacturing method of this embodiment, it is possible to selectively recover metal phenoxide from the decomposition products of the thermosetting resin curing product.

[0048] The water added to the decomposition solution A is not particularly limited and may be, for example, tap water, distilled water, deionized water, ultrapure water, etc. Furthermore, while water may be added to decomposition solution A in the form of an acidic aqueous solution in which an acid has been dissolved, it is preferable to add water that is substantially free of acid in order to avoid the conversion of metal phenoxides into phenolic compounds. Note that "substantially acid-free water" means water that is not an acidic aqueous solution in which an acid has been intentionally added, and is not intended to exclude water that inevitably contains acid (for example, water in which atmospheric carbon dioxide has been dissolved). When water contains acid, the permissible amount of acid is preferably such that the aqueous phase of oil-water two-phase liquid B is not neutralized. Specifically, the permissible amount of acid is such that the pH (at 25°C) of the aqueous phase of oil-water two-phase liquid B is preferably 3.0 or higher, more preferably 4.0 or higher, and even more preferably 5.0 or higher.

[0049] The amount of water added to decomposition solution A is not particularly limited, as long as it is sufficient to adequately extract the metal phenoxide generated in step A, and if the water contains acid, the pH of the aqueous phase of the oil-water two-phase liquid B is within the above range. Specifically, the weight ratio of water to decomposition solution is preferably 0.001 to 1000, more preferably 0.010 to 100, and even more preferably 0.050 to 10. If the amount of water is above the lower limit, the metal phenoxide can be adequately extracted. Furthermore, if the amount of organic solvent is below the upper limit, high manufacturing efficiency can be ensured without requiring a large container for metal phenoxide extraction.

[0050] Step B may be a step in which the decomposition liquid A obtained in step A is subjected to solid-liquid separation to remove insoluble matter to obtain decomposition liquid A', and water is added to decomposition liquid A' to obtain oil-water two-phase liquid B. Insoluble matter refers to, for example, substances that remain in decomposition liquid A without being decomposed together with the thermosetting resin cured product in step A, and that do not dissolve in either the aqueous or organic phase of oil-water two-phase liquid B. Examples of insoluble matter include inorganic substances and thermoplastic resins contained in the thermosetting resin cured product; other impurities; etc. If insoluble matter is present in decomposition liquid A, the insoluble matter can be removed by performing step B as described above, thereby increasing the purity of the metal phenoxide.

[0051] <1-4. Process C> Step C is a process of separating the oil-water two-phase liquid B obtained in step B to obtain metal phenoxide. Since the metal phenoxide is extracted into the aqueous phase in the oil-water two-phase liquid B, an aqueous solution of metal phenoxide can be obtained by separating the oil-water and recovering the aqueous phase.

[0052] Process C may include processes D through E below. Step D: The oil-water two-phase liquid B obtained in Step B is separated into oil-water phases, and the resulting aqueous phase C is mixed with an organic solvent to obtain suspension D. Step E: A step in which the suspension D obtained in step D is subjected to solid-liquid separation to obtain metal phenoxide from the solid phase.

[0053] Step D is a process in which the metal phenoxide dissolved in aqueous phase C is precipitated (crystallized) using an organic solvent, which is a poor solvent, to prepare suspension D. Then, step E is a process in which the precipitated metal phenoxide is recovered by solid-liquid separation, and the metal phenoxide is recovered as a solid.

[0054] The organic solvent used in step D is not particularly limited as long as it is a solvent that has low solubility for metal phenoxides and is soluble in water. Examples include ketone solvents having 1 to 8 carbon atoms such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; alcohol solvents having 1 to 6 carbon atoms such as methanol, ethanol, propanol, isopropanol, butanol, and isobutanol; and ether solvents having 1 to 6 carbon atoms such as dimethyl ether, diethyl ether, and dipropyl ether. Of these, the organic solvent is preferably a ketone solvent, and more preferably acetone, in that it can efficiently precipitate the metal phenoxide.

[0055] The method for mixing the aqueous phase C and the organic solvent in step D is not particularly limited, but from the viewpoint of reducing the amount of organic solvent used and precipitating the metal phenoxide in a short time, it is preferable to mix by dropping the aqueous phase C into the organic solvent, to remove the water in the aqueous phase C by vacuum distillation or the like and then mix with the organic solvent, or to remove the water in the aqueous phase C by vacuum distillation or the like and then dropwise add it to the organic solvent.

[0056] In step D, the weight ratio of the organic solvent to the aqueous phase C is preferably 0.001 to 1000, more preferably 0.010 to 100, and even more preferably 0.050 to 10. If the amount of organic solvent is above the lower limit, sufficient metal phenoxide can be precipitated. If the amount of organic solvent is below the upper limit, high manufacturing efficiency can be ensured without requiring a large container for the precipitation of metal phenoxide.

[0057] Furthermore, the temperature of the system obtained by mixing the organic solvent and the aqueous phase C is preferably below the boiling point of the organic solvent, more preferably below 70°C, and even more preferably below 50°C.

[0058] The method of solid-liquid separation in step E is not particularly limited, and methods such as filtration, decantation, specific gravity separation, and centrifugation can be used. Filtration may be performed at atmospheric pressure, but the time required for separation can be shortened by performing it under pressurized or reduced pressure.

[0059] <2. Method for manufacturing epoxy resin> A second embodiment of the present invention is a method for producing epoxy resin, comprising the step of reacting a metal phenoxide obtained by the production method according to the first embodiment of the present invention with an epihalohydrin. In the embodiment, the epihalohydrin may be epichlorohydrin or epibromohydrin, and epichlorohydrin is preferred. Since the manufacturing method according to this embodiment uses metal phenoxide obtained by decomposing a thermosetting resin cured product as a raw material, the epoxy resin produced by the manufacturing method according to this embodiment may hereinafter be referred to as "recycled epoxy resin".

[0060] In the manufacturing method according to this embodiment, recycled epoxy resin can be produced in accordance with a known one-step method for producing recycled epoxy resin. The one-step method for producing recycled epoxy resin is a method of obtaining recycled epoxy resin by reacting a hydroxy compound raw material with an epihalohydrin. In this embodiment, at least a portion of the hydroxy compound raw material is a metal phenoxide obtained by the manufacturing method according to the first embodiment of the present invention. The compound raw materials may also contain polyvalent hydroxy compounds (hereinafter sometimes referred to as "other polyvalent hydroxy compounds") in addition to metal phenoxides.

[0061] Here, "other polyvalent hydroxy compounds" refers to a general term for divalent or higher phenol compounds and divalent or higher alcohol compounds. In the one-step method for producing recycled epoxy resin, the "hydroxy compound raw material" is the total hydroxy compound, which includes metal phenoxide and other polyvalent hydroxy compounds used as needed.

[0062] Other polyhydric hydroxy compounds include various polyhydric phenols such as bisphenol A, tetramethylbisphenol A, bisphenol F, tetramethylbisphenol F, bisphenol S, bisphenol C, bisphenol AD, bisphenol AF, hydroquinone, resorcinol, methylresorcinol, biphenol, tetramethylbiphenol, dihydroxynaphthalene, dihydroxydiphenyl ether, thiodiphenols, phenol novolac resin, cresol novolac resin, phenol aralkyl resin, biphenyl aralkyl resin, naphthol aralkyl resin, terpene phenol resin, dicyclopentadiene phenol resin, bisphenol A novolac resin, naphthol novolac resin, brominated bisphenol A, brominated phenol novolac resin, etc.; various phenols and benzaldehyde, hydroxyben Examples include polyhydric phenolic resins obtained by condensation reactions with various aldehydes such as zualdehyde, crotonaldehyde, and glyoxal; polyhydric phenolic resins obtained by condensation reactions between xylene resin and phenols; various phenolic resins such as co-condensation resins of heavy oil or pitch with phenols and formaldehydes; linear aliphatic diols such as ethylene glycol, trimethylene glycol, propylene glycol, 1,3-butanediol, 1,4-butanediol, 1,3-pentanediol, 1,4-pentanediol, 1,5-pentanediol, and 1,6-hexanediol; cyclic aliphatic diols such as cyclohexanediol and cyclodecanediol; and polyalkylene ether glycols such as polyethylene ether glycol, polyoxytrimethylene ether glycol, and polypropylene ether glycol.

[0063] In the reaction, the metal phenoxide and other polyvalent hydroxy compounds are dissolved in the epihalohydrin to form a homogeneous solution.

[0064] The amount of epihalohydrin used is preferably 1.0 to 14.0 equivalents, and particularly 2.0 to 10.0 equivalents, per equivalent of the total hydroxyl groups of the hydroxy compound raw material (all hydroxy compounds). A higher amount of epihalohydrin than the lower limit is preferable because it facilitates the control of the high molecular weight reaction and allows the resulting regenerated epoxy resin to have an appropriate epoxy equivalent. On the other hand, a lower amount of epihalohydrin than the upper limit is preferable because it tends to improve production efficiency.

[0065] Next, while stirring the above solution, an alkali metal hydroxide in solid or aqueous solution is added in an amount typically equivalent to 0.1 to 3.0 equivalents, preferably 0.8 to 2.0 equivalents, per equivalent of the total hydroxyl groups of the hydroxy compound raw material, and the reaction is carried out. It is preferable that the amount of alkali metal hydroxide added is above the lower limit above, as this makes it difficult for the unreacted hydroxyl groups to react with the generated epoxy resin, and makes it easier to control the high molecular weight reaction. It is also preferable that the amount of alkali metal hydroxide added is below the upper limit above, as this makes it difficult for impurities to be generated by side reactions. Typical alkali metal hydroxides used here include sodium hydroxide or potassium hydroxide.

[0066] This reaction can be carried out under normal pressure or reduced pressure, and the reaction temperature is preferably 20 to 200°C, more preferably 40 to 150°C. A reaction temperature above the lower limit is preferable because it facilitates the reaction and makes it easier to control. A reaction temperature below the upper limit is preferable because it reduces the likelihood of side reactions and makes it easier to reduce the amount of polymer.

[0067] Furthermore, this reaction is carried out while dehydrating by azeotropizing the reaction mixture while maintaining a predetermined temperature as needed, cooling the volatile vapor to obtain a condensate, separating the oil / water, and returning the oil, from which the water has been removed, to the reaction system. To suppress the rapid reaction, alkali metal hydroxide is preferably added intermittently or continuously in small amounts over 0.1 to 24 hours, more preferably over 0.5 to 10 hours. Adding alkali metal hydroxide for a time greater than or equal to the lower limit is preferable because it prevents the reaction from proceeding too rapidly and makes it easier to control the reaction temperature. Adding for a time less than or equal to the upper limit is preferable because it makes it easier to reduce the amount of polymer.

[0068] After the reaction is complete, the insoluble by-product salt can be removed by filtration or washing with water, and then the unreacted epihalohydrin can be removed by heating and / or distillation under reduced pressure.

[0069] Furthermore, catalysts such as quaternary ammonium salts like tetramethylammonium chloride and tetraethylammonium bromide; tertiary amines like benzyldimethylamine and 2,4,6-tris(dimethylaminomethyl)phenol; imidazoles like 2-ethyl-4-methylimidazole and 2-phenylimidazole; phosphonium salts like ethyltriphenylphosphonium iodide; and phosphines like triphenylphosphine may be used in this reaction.

[0070] Furthermore, in this reaction, inert organic solvents such as alcohols (ethanol, isopropanol, etc.), ketones (acetone, methyl ethyl ketone, methyl isobutyl ketone, etc.), ethers (dioxane, ethylene glycol dimethyl ether, etc.), glycol ethers (methoxypropanol, etc.), and aprotic polar solvents (dimethyl sulfoxide, dimethylformamide, etc.) may be used.

[0071] [Manufacturing of recycled epoxy resin with reduced total chlorine content] If it is necessary to reduce the total chlorine content of the recycled epoxy resin obtained as described above, a recycled epoxy resin with a reduced total chlorine content can be produced by reaction with an alkali.

[0072] For the reaction with alkali, an organic solvent for dissolving the recycled epoxy resin may be used. While there are no particular restrictions on the organic solvent used in the reaction, it is preferable to use a ketone-based organic solvent from the standpoint of manufacturing efficiency, handling, and workability. Furthermore, aprotic polar solvents may be used from the viewpoint of further reducing the amount of hydrolyzable chlorine.

[0073] Examples of ketone-based organic solvents include methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone. Methyl isobutyl ketone is particularly preferred due to its effectiveness and ease of post-treatment. These may be used individually or in combination of two or more.

[0074] Examples of aprotic polar solvents include dimethyl sulfoxide, diethyl sulfoxide, dimethyl sulfone, sulfolane, dimethylformamide, dimethylacetamide, and hexamethylphosphoramide. These may be used individually or in combination of two or more. Among these aprotic polar solvents, dimethyl sulfoxide is preferred because it is readily available and has excellent efficacy.

[0075] The amount of solvent used is such that the concentration of the recycled epoxy resin in the liquid subjected to alkaline treatment is typically 1 to 95% by mass, preferably 5 to 80% by mass.

[0076] As the alkali, a solid or solution of alkali metal hydroxide can be used. Examples of alkali metal hydroxides include potassium hydroxide and sodium hydroxide, with sodium hydroxide being preferred. Alternatively, alkali metal hydroxides may be used in solutions of organic solvents or water. Preferably, alkali metal hydroxides are used as a solution in aqueous or organic solvent.

[0077] The amount of alkali metal hydroxide used is preferably 0.01 to 20.0 parts by mass or less per 100 parts by mass of recycled epoxy resin, calculated as the solid content of the alkali metal hydroxide. More preferably, it is 0.10 to 10.0 parts by mass. If the amount of alkali metal hydroxide used is below the lower limit, the effect of reducing the total chlorine content is low, and if it is above the upper limit, a large amount of polymer is produced, resulting in a decrease in yield.

[0078] The reaction temperature is preferably 20 to 200°C, more preferably 40 to 150°C, and the reaction time is preferably 0.1 to 24 hours, more preferably 0.5 to 10 hours. After the reaction, excess alkali metal hydroxides and by-product salts can be removed by methods such as washing with water, and the organic solvent can be further removed by heating and / or reduced-pressure distillation and / or steam distillation.

[0079] <3. Method for manufacturing epoxy resin> A third embodiment of the present invention is a method for producing epoxy resin, comprising the step of reacting an epoxy resin obtained by the production method according to the second embodiment of the present invention with a polyvalent hydroxy compound. In this embodiment, the polyvalent hydroxy compound is a general term for divalent or higher phenolic compounds and divalent or higher alcohols. Since the manufacturing method according to this embodiment uses metal phenoxide obtained by decomposing a thermosetting resin cured product as a raw material, the epoxy resin produced by the manufacturing method according to this embodiment may hereinafter be referred to as "recycled epoxy resin".

[0080] In the manufacturing method according to this embodiment, recycled epoxy resin can be produced in accordance with a known two-stage method for producing recycled epoxy resin. The two-stage method for producing recycled epoxy resin includes a step of reacting an epoxy resin raw material with a polyvalent hydroxy compound raw material. In this embodiment, at least a portion of the epoxy resin raw material is an epoxy resin obtained by the manufacturing method according to the second embodiment of the present invention.

[0081] In other words, the method for producing recycled epoxy resin by a two-stage method involves reacting an epoxy resin raw material containing the epoxy resin obtained by the production method according to the second embodiment of the present invention with a polyvalent hydroxy compound raw material containing a polyvalent hydroxy compound.

[0082] The epoxy resin raw material may contain other epoxy resins as needed, in addition to the epoxy resin obtained by the manufacturing method according to the second embodiment of the present invention.

[0083] Other epoxy resins are as described later in the method for producing an epoxy resin cured product according to the fourth embodiment of the present invention, and the polyvalent hydroxy compound is the same as the other polyvalent hydroxy compound in the method for producing a recycled epoxy resin according to the fourth embodiment of the present invention.

[0084] The recycled epoxy resin content in the epoxy resin raw material is not particularly limited, but a higher recycled epoxy resin content is more environmentally friendly, so 1 to 100% by mass is preferred, and 10 to 100% by mass is more preferred.

[0085] In the two-stage reaction, the amounts of epoxy resin raw material and polyvalent hydroxy compound raw material used are preferably in an equivalent ratio of (epoxy group equivalent):(hydroxyl group equivalent) = 1:0.1 to 2.0. More preferably, it is 1:0.2 to 1.2. When this equivalent ratio is within the above range, it is easier to increase the molecular weight and retain more epoxy group terminals. This is preferable because it allows for this.

[0086] Furthermore, a catalyst may be used in the two-stage reaction, and any compound that has catalytic activity to promote the reaction between epoxy groups and phenolic hydroxyl groups or alcoholic hydroxyl groups can be used as the catalyst. Examples include alkali metal compounds, organophosphorus compounds, tertiary amines, quaternary ammonium salts, cyclic amines, and imidazoles. Among these, quaternary ammonium salts are preferred. In addition, one type of catalyst may be used, or two or more types may be used in combination. The amount of catalyst used is usually 0.001 to 10% by mass relative to the epoxy resin raw material.

[0087] Furthermore, in the two-stage reaction, a solvent may be used, and any solvent that dissolves the epoxy resin raw material can be used. Examples include aromatic solvents, ketone solvents, amide solvents, glycol ether solvents, etc. Only one solvent may be used, or two or more may be used in combination. The resin concentration in the solvent is preferably 10 to 95% by mass, more preferably 20 to 80% by mass. If a highly viscous product is formed during the reaction, additional solvent may be added to continue the reaction. After the reaction is complete, the solvent may be removed or added as needed.

[0088] In the two-stage reaction, the reaction temperature is preferably 20 to 250°C, more preferably 50 to 200°C. If the reaction temperature is above the upper limit, the resulting epoxy resin may deteriorate. If it is below the lower limit, the reaction may not proceed sufficiently. The reaction time is usually 0.1 to 24 hours, preferably 0.5 to 12 hours.

[0089] <4. Method for manufacturing cured epoxy resin products> A fourth embodiment of the present invention is a method for producing a cured epoxy resin product, comprising the step of curing an epoxy resin composition containing a recycled epoxy resin and a curing agent obtained by a manufacturing method according to the second or third embodiment of the present invention. It is also possible to obtain a composite material again by further blending inorganic substances into the epoxy resin composition and curing this epoxy resin composition. According to this embodiment, a new chemical recycling method can be established in this way.

[0090] In this embodiment, the epoxy resin composition may optionally contain other epoxy resins other than the recycled epoxy resin obtained by the manufacturing method according to the second or third embodiment of the present invention, as well as curing agents, curing accelerators, inorganic fillers, coupling agents, etc.

[0091] The content of recycled epoxy resin in the epoxy resin composition is not particularly limited. A higher content of recycled epoxy resin is environmentally friendly, so it is preferable that the recycled epoxy resin is 40 parts by mass or more, and more preferably 60 parts by mass or more, per 100 parts by mass of the total epoxy resin components in the epoxy resin composition. When other epoxy resins are included, the recycled epoxy resin can be 40 to 99 parts by mass, 60 to 99 parts by mass, etc., per 100 parts by mass of the total epoxy resin components in the epoxy resin composition. Note that "total epoxy resin components" refers to the total amount of epoxy resin contained in the epoxy resin composition, and is the sum of recycled epoxy resin and other epoxy resins used as needed.

[0092] (Hardening agent) The curing agent contained in the epoxy resin composition refers to a substance that contributes to the crosslinking reaction and / or chain length extension reaction between the epoxy groups of the epoxy resin. In this embodiment, even substances that are normally called "curing accelerators" will be considered curing agents if they contribute to the crosslinking reaction and / or chain length extension reaction between the epoxy groups of the epoxy resin.

[0093] In the epoxy resin composition, the curing agent content is as follows: per 100 parts by mass of the total epoxy resin components. Preferably, the amount is 0.1 to 1000 parts by mass. More preferably, it is 500 parts by mass or less.

[0094] There are no particular restrictions on the curing agent; all commonly known epoxy resin curing agents can be used. Examples include phenolic curing agents, aliphatic amines, polyetheramines, alicyclic amines, and aromatic amines; acid anhydride curing agents; amide curing agents; tertiary amines; imidazoles; and the like. One curing agent may be used alone, or two or more may be used in combination. When two or more curing agents are used in combination, they may be mixed beforehand to prepare a mixed curing agent before use, or the components of the curing agents may be added separately and mixed simultaneously when mixing the recycled epoxy resin obtained by the manufacturing method according to the second or third embodiment of the present invention with other epoxy resins.

[0095] Specific examples of phenolic curing agents include bisphenol compounds, bisphenol A, tetramethylbisphenol A, bisphenol F, tetramethylbisphenol F, bisphenol C, bisphenol S, bisphenol AD, bisphenol AF, hydroquinone, resorcinol, methylresorcinol, biphenol, tetramethylbiphenol, dihydroxynaphthalene, dihydroxydiphenyl ether, thiodiphenols, phenol novolac resin, cresol novolac resin, phenol aralkyl resin, biphenyl aralkyl resin, naphthol aralkyl resin, terpene phenol resin, dicyclopentadiene phenol resin, bisphenol A novolac resin, trisphenolmethane type resin, naphthol novolac resin, and brominated bisphenols. Examples include various polyhydric phenols such as phenol A and brominated phenol novolac resins, polyhydric phenol resins obtained by condensation reactions of various phenols with various aldehydes such as benzaldehyde, hydroxybenzaldehyde, crotonaldehyde, and glyoxal, polyhydric phenol resins obtained by condensation reactions of xylene resin with phenols, co-condensation resins of heavy oil or pitch with phenols and formaldehydes, various phenol resins such as phenol-benzaldehyde-xylylenedimethoxide polycondensate, phenol-benzaldehyde-xylylenedihalide polycondensate, phenol-benzaldehyde-4,4'-dimethoxide biphenyl polycondensate, and phenol-benzaldehyde-4,4'-dihalide biphenyl polycondensate.

[0096] These phenolic curing agents may be used individually or in any combination and mixing ratio of two or more types.

[0097] The amount of phenolic curing agent blended is preferably 0.1 to 1000 parts by mass, and more preferably 500 parts by mass or less, per 100 parts by mass of the total epoxy resin components in the epoxy resin composition.

[0098] Examples of amine-based curing agents (excluding tertiary amines) include aliphatic amines, polyetheramines, alicyclic amines, and aromatic amines.

[0099] Examples of aliphatic amines include ethylenediamine, 1,3-diaminopropane, 1,4-diaminopropane, hexamethylenediamine, 2,5-dimethylhexamethylenediamine, trimethylhexamethylenediamine, diethylenetriamine, iminobispropylamine, bis(hexamethylene)triamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, N-hydroxyethylethylenediamine, and tetra(hydroxyethyl)ethylenediamine.

[0100] Examples of polyetheramines include triethylene glycol diamine, tetraethylene glycol diamine, diethylene glycol bis(propylamine), and polyoxypropylene Examples include diamines and polyoxypropylene triamines.

[0101] Examples of alicyclic amines include isophoronediamine, metacenediamine, N-aminoethylpiperazine, bis(4-amino-3-methyldicyclohexyl)methane, bis(aminomethyl)cyclohexane, 3,9-bis(3-aminopropyl)-2,4,8,10-tetraoxaspiro(5,5)undecane, and norbornenediamine.

[0102] Examples of aromatic amines include tetrachloro-p-xylenediamine, m-xylenediamine, p-xylenediamine, m-phenylenediamine, o-phenylenediamine, p-phenylenediamine, 2,4-diaminoanisole, 2,4-toluenediamine, 2,4-diaminodiphenylmethane, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylethane, 4,4'-diamino-1,2-diphenylethane, 2,4-diaminodiphenylsulfone, 4,4'-diaminodiphenylsulfone, m-aminophenol, m-aminobenzylamine, benzyldimethylamine, 2-(dimethylaminomethyl)phenol, triethanolamine, methylbenzylamine, α-(m-aminophenyl)ethylamine, α-(p-aminophenyl)ethylamine, diaminodiethyldimethyldiphenylmethane, and α,α'-bis(4-aminophenyl)-p-diisopropylbenzene.

[0103] The amine-based curing agents listed above may be used individually or in any combination and mixing ratio of two or more types.

[0104] The above-mentioned amine-based curing agent is preferably used such that the equivalent ratio of functional groups in the curing agent to epoxy groups in the total epoxy resin components contained in the epoxy resin composition is in the range of 0.1 to 2.0. More preferably, the equivalent ratio is in the range of 0.8 to 1.2. This range is preferable because it makes it less likely for unreacted epoxy groups or functional groups of the curing agent to remain.

[0105] Examples of tertiary amines include 1,8-diazabicyclo(5,4,0)undecene-7, triethylenediamine, benzyldimethylamine, triethanolamine, dimethylaminoethanol, and tris(dimethylaminomethyl)phenol. The tertiary amines listed above may be used individually or in any combination and proportion.

[0106] The above-mentioned tertiary amine is preferably used in such a way that the equivalent ratio of functional groups in the curing agent to epoxy groups in the total epoxy resin components contained in the epoxy resin composition is in the range of 0.1 to 2.0. More preferably, the equivalent ratio is in the range of 0.8 to 1.2. This range is preferable because it makes it less likely for unreacted epoxy groups or functional groups of the curing agent to remain.

[0107] Examples of acid anhydride-based curing agents include acid anhydrides and modified acid anhydrides.

[0108] Examples of acid anhydrides include phthalic anhydride, trimellitic anhydride, pyromellitic anhydride, benzophenonetetracarboxylic anhydride, dodecenyl succinic anhydride, polyadipic anhydride, polyazelaic anhydride, polysebacic anhydride, poly(ethyloctadecanediic acid) anhydride, poly(phenylhexadecanedioic acid) anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, hexahydrophthalic anhydride, and methylhymic acid. Anhydride, trialkyltetrahydrophthalic anhydride, methylcyclohexenedicarboxylic acid anhydride, methylcyclohexenetetracarboxylic acid anhydride, ethylene glycol bistrimellitate dianhydride, hetic acid anhydride, nadic acid anhydride, methylnadic acid anhydride, 5-(2,5-dioxotetrahydro-3-furanyl)-3-methyl-3-cyclohexane-1,2-dicarboxylic acid anhydride, 3,4-dicarboxy-1,2,3,4-tetrahydro-1-naphthalene succinic acid dianhydride, and 1- Examples include methyl-dicarboxy-1,2,3,4-tetrahydro-1-naphthalene succinic acid dianhydride.

[0109] Examples of modified acid anhydrides include those obtained by modifying the aforementioned acid anhydrides with glycols. Examples of glycols that can be used for modification include alkylene glycols such as ethylene glycol, propylene glycol, and neopentyl glycol; and polyether glycols such as polyethylene glycol, polypropylene glycol, and polytetramethylene ether glycol. Furthermore, copolymer polyether glycols of two or more of these glycols and / or polyether glycols can also be used.

[0110] The acid anhydride-based curing agents listed above may be used individually or in any combination and proportion.

[0111] When using an acid anhydride-based curing agent, it is preferable to use one such agent so that the equivalent ratio of functional groups in the curing agent to epoxy groups in the total epoxy resin components of the epoxy resin composition is in the range of 0.1 to 2.0. More preferably, the equivalent ratio is in the range of 0.8 to 1.2. This range is preferable because it reduces the likelihood of unreacted epoxy groups or functional groups of the curing agent remaining in the mixture.

[0112] Examples of amide-based curing agents include dicyandiamide and its derivatives, and polyamide resins. The amide-based curing agent may be used alone, or two or more types may be mixed in any combination and ratio. When using an amide-based curing agent, it is preferable to use it in such a way that the amount of amide-based curing agent is 0.1 to 20% by mass relative to the total amount of epoxy resin components and amide-based curing agent in the epoxy resin composition.

[0113] Imidazoles include 2-phenylimidazole, 2-ethyl-4(5)-methylimidazole, 2-phenyl-4-methylimidazole, 1-benzyl-2-methylimidazole, 1-benzyl-2-phenylimidazole, 1-cyanoethyl-2-undecylimidazole, 1-cyano-2-phenylimidazole, 1-cyanoethyl-2-undecylimidazole trimellitate, 1-cyanoethyl-2-phenylimidazolium trimellitate, and 2,4-diamino-6-[2'-methylimidazolyl- Examples include (1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-ethyl-4'-methylimidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine isocyanurate adduct, 2-phenylimidazole isocyanurate adduct, 2-phenyl-4,5-dihydroxymethylimidazole, 2-phenyl-4-methyl-5-hydroxymethylimidazole, and adducts of epoxy resins with the above imidazoles. Although imidazoles generally have catalytic activity and can be classified as curing accelerators, in this invention they are classified as curing agents. The imidazoles listed above may be used individually or as a mixture of two or more in any combination and ratio.

[0114] When using imidazoles, it is preferable that the amount of imidazoles in the epoxy resin composition be 0.1 to 20% by mass relative to the total amount of all epoxy resin components and imidazoles in the epoxy resin composition.

[0115] In epoxy resin compositions, other curing agents can be used in addition to the curing agent mentioned above. There are no particular restrictions on other curing agents that can be used in epoxy resin compositions; they are generally not limited to those mentioned above. Any known epoxy resin curing agent can be used. These other hardening agents may be used individually or in combination of two or more.

[0116] (Other epoxy resins) The epoxy resin composition may contain other epoxy resins (other epoxy resins) in addition to the recycled epoxy resin obtained by the manufacturing method according to the second or third embodiment of the present invention. By including other epoxy resins, various physical properties can be improved.

[0117] Other epoxy resins that can be used in epoxy resin compositions include all epoxy resins other than the recycled epoxy resin obtained by the manufacturing method according to the second or third embodiment of the present invention.Specific examples include bisphenol A type epoxy resin, bisphenol C type epoxy resin, trisphenolmethane type epoxy resin, anthracene type epoxy resin, phenol-modified xylene resin type epoxy resin, bisphenolcyclododecyl type epoxy resin, bisphenoldiisopropylidene resorcinol type epoxy resin, bisphenol F type epoxy resin, bisphenol AD ​​type epoxy resin, bisphenol AF type epoxy resin, hydroquinone type epoxy resin, methylhydroquinone type epoxy resin, dibutylhydroquinone type epoxy resin, resorcinol type epoxy resin, methylresorcinol type epoxy resin, biphenol type epoxy resin, tetramethylbiphenol type epoxy resin, tetramethylbisphenol F type epoxy resin, dihydroxydiphenyl ether type epoxy resin, epoxy resins derived from thiodiphenols, dihydroxynaphthalene type epoxy resin, dihydroxyanthracene type epoxy resin, dihydroxydihydroanthracene type epoxy resin, dicyclopentadiene type epoxy resin, dihydro Examples include epoxy resins derived from xistilbenes, phenol novolac type epoxy resins, cresol novolac type epoxy resins, bisphenol A novolac type epoxy resins, naphthol novolac type epoxy resins, phenol aralkyl type epoxy resins, naphthol aralkyl type epoxy resins, biphenyl aralkyl type epoxy resins, terpene phenol type epoxy resins, dicyclopentadiene phenol type epoxy resins, epoxy resins derived from phenol-hydroxybenzaldehyde condensates, epoxy resins derived from phenol-crotonaldehyde condensates, epoxy resins derived from phenol-glyoxal condensates, epoxy resins derived from co-condensation resins of heavy oils or pitches with phenols and formaldehydes, epoxy resins derived from diaminodiphenylmethane, epoxy resins derived from aminophenols, epoxy resins derived from xylenediamine, epoxy resins derived from methylhexahydrophthalic acid, and epoxy resins derived from dimer acids. These may be used individually, or two or more may be used in any combination and ratio.

[0118] If the epoxy resin composition contains the above-mentioned other epoxy resins, the content thereof is preferably 1 to 60 parts by mass, and more preferably 40 parts by mass or less, based on 100 parts by mass of the total epoxy resin components in the composition.

[0119] (Curing accelerator) The epoxy resin composition preferably contains a curing accelerator. The inclusion of a curing accelerator allows for a reduction in curing time and a lower curing temperature, making it easier to obtain the desired cured product.

[0120] The curing accelerator is not particularly limited, but specific examples include organophosphines, phosphorus compounds such as phosphonium salts, tetraphenylboron salts, organic acid dihydrazides, and boron halide amine complexes.

[0121] Phosphorus compounds that can be used as curing accelerators include triphenylphosphine and diphenylphosphine. Nyl(p-tolyl)phosphine, tris(alkylphenyl)phosphine, tris(alkoxyphenyl)phosphine, tris(alkyl·alkoxyphenyl)phosphine, tris(dialkylphenyl)phosphine, tris(trialkylphenyl)phosphine, tris(tetraalkylphenyl)phosphine, tris(dialkoxyphenyl)phosphine, tris(trialkoxyphenyl)phosphine, tris(tetraalkoxyphenyl)phosphine, trialkylphosphine, dialkylarylphosphine, and Examples include organophosphines such as alkyldiarylphosphines; complexes of these organophosphines with organoborons; compounds obtained by adding these organophosphines with quinone compounds such as maleic anhydride, 1,4-benzoquinone, 2,5-tholquinone, 1,4-naphthoquinone, 2,3-dimethylbenzoquinone, 2,6-dimethylbenzoquinone, 2,3-dimethoxy-5-methyl-1,4-benzoquinone, 2,3-dimethoxy-1,4-benzoquinone, phenyl-1,4-benzoquinone, and diazophenylmethane; and others.

[0122] Among the curing accelerators listed above, organophosphines and phosphonium salts are preferred, with organophosphines being the most preferred. Furthermore, the curing accelerator may be used individually from those listed above, or two or more may be mixed in any combination and ratio.

[0123] The curing accelerator is preferably used in an amount of 0.1 parts by mass or more and 20 parts by mass or less per 100 parts by mass of the total epoxy resin components in the epoxy resin composition. A curing accelerator content above the lower limit is preferable because a good curing acceleration effect can be obtained, while a content below the upper limit is preferable because it is easier to obtain the desired cured physical properties.

[0124] (Inorganic filler) Inorganic fillers can be added to epoxy resin compositions. Examples of inorganic fillers include fused silica, crystalline silica, glass powder, alumina, calcium carbonate, calcium sulfate, talc, and boron nitride. These may be used individually or in any combination and ratio of two or more. The amount of inorganic filler added is preferably 10 to 95% by mass of the total epoxy resin composition.

[0125] (Release agent) Release agents can be added to epoxy resin compositions. Examples of release agents include natural waxes such as carnauba wax, synthetic waxes such as polyethylene wax, higher fatty acids such as stearic acid and zinc stearate and their metal salts, and hydrocarbon-based release agents such as paraffin. These may be used individually or in any combination and ratio of two or more.

[0126] The amount of release agent added is preferably 0.001 to 10.0 parts by mass per 100 parts by mass of the total epoxy resin components in the epoxy resin composition. This range of release agent addition is preferable because it allows for good release properties while maintaining curing characteristics.

[0127] (Coupling agent) Coupling agents can be incorporated into epoxy resin compositions. It is preferable to use coupling agents in combination with inorganic fillers, as the inclusion of coupling agents can improve the adhesion between the epoxy resin matrix and the inorganic fillers. Examples of coupling agents include silane coupling agents and titanate coupling agents.

[0128] Examples of silane coupling agents include epoxysilanes such as γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, and β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, as well as γ-aminopropyltriethoxysilane, N-β(aminoethyl)γ-aminopropyltrimethoxysilane, and N-β(aminoethyl). Examples include aminosilanes such as noethyl)γ-aminopropylmethyldimethoxysilane, γ-aminopropyltrimethoxysilane, and γ-ureidopropyltriethoxysilane; mercaptosilanes such as 3-mercaptopropyltrimethoxysilane; vinylsilanes such as p-styryltrimethoxysilane, vinyltrichlorosilane, vinyltris(β-methoxyethoxy)silane, vinyltrimethoxysilane, vinyltriethoxysilane, and γ-methacryloxypropyltrimethoxysilane; and also epoxy, amino, and vinyl polymer type silanes.

[0129] Examples of titanate coupling agents include isopropyl triisostearoyl titanate, isopropyl tri(N-aminoethyl / aminoethyl) titanate, diisopropyl bis(dioctyl phosphate) titanate, tetraisopropyl bis(dioctyl phosphite) titanate, tetraoctyl bis(ditridecyl phosphite) titanate, tetra(2,2-diallyloxymethyl-1-butyl)bis(ditridecyl) phosphite titanate, bis(dioctyl pyrophosphate) oxyacetate titanate, and bis(dioctyl pyrophosphate) ethylene titanate.

[0130] These coupling agents may be used individually, or two or more may be mixed in any combination and ratio.

[0131] When a coupling agent is used in an epoxy resin composition, the amount of the coupling agent is preferably 0.001 to 10.0 parts by mass per 100 parts by mass of the total epoxy resin component. If the amount of the coupling agent is above the lower limit, the effect of improving the adhesion between the epoxy resin matrix and the inorganic filler due to the addition of the coupling agent tends to improve. On the other hand, if the amount of the coupling agent is below the upper limit, the coupling agent is less likely to bleed out from the resulting cured product, which is preferable.

[0132] (Other ingredients) The epoxy resin composition may contain components other than those mentioned above. Examples of other components include flame retardants, plasticizers, reactive diluents, and pigments, which may be added as needed. However, this does not preclude the inclusion of components other than those listed above.

[0133] Examples of flame retardants include halogen-based flame retardants such as brominated epoxy resins and brominated phenol resins; antimony compounds such as antimony trioxide; phosphorus-based flame retardants such as red phosphorus, phosphate esters, and phosphines; nitrogen-based flame retardants such as melamine derivatives; and inorganic flame retardants such as aluminum hydroxide and magnesium hydroxide.

[0134] (Curing method) An epoxy resin cured product can be obtained by curing an epoxy resin composition. While there are no particular limitations on the curing method, the cured product is usually obtained by a thermosetting reaction through heating. During the thermosetting reaction, it is preferable to appropriately select the curing temperature depending on the type of curing agent used. For example, when using a phenolic curing agent, the curing temperature is usually 80 to 250°C. It is also possible to lower the curing temperature by adding a curing accelerator to these curing agents. The reaction time is preferably 0.01 to 20 hours. A reaction time above the lower limit is preferable because it tends to allow the curing reaction to proceed sufficiently. On the other hand, a reaction time below the upper limit is preferable because it reduces degradation due to heating and energy loss during heating.

[0135] (Application) The epoxy resin cured product obtained by curing the epoxy resin composition has a low coefficient of thermal expansion and is resistant to It has excellent thermal crack resistance. Therefore, epoxy resin cured products can be effectively used in any application where these physical properties are required. For example, they can be suitably used in the fields of paints, such as electrodeposition coatings for automobiles, heavy-duty anticorrosive coatings for ships and bridges, and coatings for the interior of beverage cans; in the fields of electrical and electronics, such as laminates, semiconductor encapsulants, insulating powder coatings, and coil impregnation; and in the fields of civil engineering, construction, and adhesives, such as seismic reinforcement of bridges, concrete reinforcement, flooring materials for buildings, linings for water supply facilities, drainage and permeable pavements, and adhesives for vehicles and aircraft.

[0136] The epoxy resin composition may be used after curing for the aforementioned application, or it may be cured during the manufacturing process for the aforementioned application. [Examples]

[0137] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples unless it exceeds the gist of the invention.

[0138] [Raw materials and reagents] The bisphenol A type epoxy resins (epoxy equivalents of 950 and 183) used were products of Mitsubishi Chemical Corporation. The Ricasid M-700 (acid anhydride) used was a product of Shin Nippon Rika Co., Ltd. The curing catalyst used was a product of Shikoku Chemicals Co., Ltd. The phenol novolac resin (PSM-4261) used was a product of Gun-ei Chemical Industry Co., Ltd. The 48% by mass sodium hydroxide aqueous solution, sodium bicarbonate, disylenediamide (DICY), and 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) were products of Fujifilm Wako Pure Chemical Industries, Ltd. The benzyl alcohol used was a product of Sankyo Chemical Co., Ltd.

[0139] [analysis] The formation, purity, and quantification of bisphenol A were confirmed, and the procedure for determining its quantity was performed by high-performance liquid chromatography under the following conditions. • Equipment: JASCO RHPLC, JASCO 03150-3M Unifinepak C18 3μm 150mm×3.0mm ID Method: Gradient method ·Analysis temperature: 40℃ ·Eluent composition: Solution A: Acetonitrile B liquid water At 0 minutes of analysis time, the ratio of solution A to solution B was 30:70 (volume ratio, the same applies below). From 0 to 25 minutes of analysis time, the ratio of solution A to solution B was gradually increased to 100:0. ·Flow rate: 0.40mL / min • Detection wavelength: 280nm

[0140] <Example 1> Mixture a was obtained by placing 500g of bisphenol A type epoxy resin (epoxy equivalent 950) and 10g of a 5% by mass sodium bicarbonate aqueous solution into an aluminum cup and mixing thoroughly. The resulting mixture a was cured at 200°C for 100 hours to obtain a single resin cured product.

[0141] In a separable flask equipped with a stirring blade, condenser, and thermometer, 630 g of benzyl alcohol and 50 g of a 48% by mass sodium hydroxide aqueous solution were placed under a nitrogen atmosphere. After creating a full vacuum inside the flask, the internal temperature was gradually increased, and some of the water and benzyl alcohol was removed, completely distilling off the water in the separable flask. The separable flask was then repressurized with nitrogen to obtain 640 g of the treatment solution.

[0142] 640 g of the obtained processing solution was mixed with 60 g of the single resin cured product, and the mixture was heated to 200°C over 1 hour at atmospheric pressure. The contents of the separable flask were maintained at 200°C for 3 hours, completely dissolving the single resin cured product and yielding 700 g of decomposition solution a. A portion of the obtained decomposition solution a was analyzed by high-performance liquid chromatography and confirmed that it contained 4.1% by mass of bisphenol A·2Na (4.1% by mass × 700 g = 28.7 g).

[0143] 700 g of decomposition solution a was added to 700 g of water, and 650 g of aqueous phase a was obtained by oil-water separation at room temperature. The aqueous phase a was concentrated five-fold by removing the water under reduced pressure, and the concentrate was added dropwise to 2800 g of acetone to obtain suspension a. Suspension a was filtered, and the filtrate was air-dried to obtain 44 g of solid a. A portion of the obtained solid a was analyzed by high-performance liquid chromatography and confirmed to contain 37.7% by mass of bisphenol A·2Na (37.7% by mass × 44 g = 16.6 g).

[0144] <Comparative Example 1> In a jacketed separable flask equipped with a Liebig condenser, a stirring blade, and a thermometer, 500 g of the decomposition solution a obtained in Example 1 was placed under a nitrogen atmosphere and heated to 80°C. While maintaining the internal temperature at 80°C, the decomposition solution a was neutralized with hydrochloric acid.

[0145] Subsequently, the mixture was allowed to stand to separate the oil and water, and aqueous phase b was extracted to obtain organic phase b. 150 g of water was added to the obtained organic phase b and mixed while maintaining the internal temperature at 80°C. Subsequently, the mixture was allowed to stand to separate the oil and water, and aqueous phase b' was extracted to obtain organic phase b'. The obtained organic phase b' was cooled to 10°C, but no suspension containing bisphenol A·2Na was obtained.

[0146] <Comparative Example 2> 500 g of the decomposition solution a obtained in Example 1 was placed in a jacketed separable flask equipped with a Liebig condenser, a stirring blade, and a thermometer, and the temperature was raised to 80°C under a nitrogen atmosphere. The temperature was then lowered to 10°C, but no suspension containing bisphenol A·2Na was obtained.

[0147] [Table 1]

[0148] Table 1 summarizes the presence or absence of water extraction of decomposition solution a, neutralization, crystallization, and bisphenol A in Example 1 and Comparative Examples 1 and 2. From Table 1, it can be seen that bisphenol A-2Na can be obtained by water extraction of decomposition solution a.

[0149] <Example 2> In an aluminum cup, 300g of bisphenol A type epoxy resin (epoxy equivalent 183) Mixture C was obtained by adding g, 270 g of Ricacid, and 3 g of Curesol 2E4MZ and mixing well. The obtained mixture C was heated at 100°C for 3 hours, and then at 140°C for 3 hours to obtain a cured acid anhydride.

[0150] Except for using 60 g of the aforementioned acid anhydride cured product as the thermosetting resin, the procedure was carried out in the same manner as in Example 1 to obtain 700 g of decomposition solution c. When the composition of a portion of the obtained decomposition solution c was confirmed by high-performance liquid chromatography, it was found to contain 3.5% by mass (3.5% by mass × 700 g = 24.5 g) of bisphenol A·2Na.

[0151] Subsequently, the same procedure as in Example 1 was followed to obtain 64.3 g of solid c. A portion of the obtained solid c was analyzed by high-performance liquid chromatography, and it was confirmed that it contained 21.9% (21.9% by mass × 64.3 g = 14.1 g) of bisphenol A·2Na.

[0152] <Example 3> Mixture D was obtained by thoroughly mixing 280g of bisphenol A type epoxy resin (epoxy equivalent 183), 2g of DICY, and 3g of DCMU in an aluminum cup. The resulting mixture D was heated at 150°C for 3 hours to obtain an amine-cured product.

[0153] Except for using 60 g of the amine cured product as the thermosetting resin, the procedure was carried out in the same manner as in Example 1 to obtain 700 g of decomposition solution d. When the composition of a portion of the obtained decomposition solution d was confirmed by high-performance liquid chromatography, it was found to contain 3.1% by mass of bisphenol A·2Na (3.1% by mass × 700 g = 21.7 g).

[0154] Subsequently, the same procedure as in Example 1 was followed to obtain 69.1 g of solid d. When the composition of a portion of the obtained solid d was examined by high-performance liquid chromatography, it was confirmed that it contained 23.3% by mass of bisphenol A·2Na (23.3% by mass × 69.1 g = 16.1 g).

[0155] <Example 4> Mixture e was obtained by thoroughly mixing 280g of bisphenol A type epoxy resin (epoxy equivalent 183), 172g of phenol novolac resin (PSM-4261), and 2g of Curesol 2E4MZ in an aluminum cup. The resulting mixture e was heated at 120°C for 2 hours, and then at 175°C for 6 hours to obtain a phenol cured product.

[0156] Except for using 60 g of the phenol cured product as the thermosetting resin, the procedure was carried out in the same manner as in Example 1 to obtain 700 g of decomposition solution e. Since insoluble matter was observed in decomposition solution e, this insoluble matter was filtered off to obtain decomposition solution e'. When the composition of a portion of the obtained decomposition solution e' was confirmed by high-performance liquid chromatography, it was found to contain 2.4% by mass (2.4% by mass × 700 g = 16.8 g) of bisphenol A·2Na.

[0157] Subsequently, the same procedure as in Example 1 was followed to obtain 32.0 g of solid e. A portion of the obtained solid e was analyzed by high-performance liquid chromatography and confirmed to contain 28.4% by mass of bisphenol A·2Na (28.4% by mass × 32.0 g = 9.1 g).

[0158] [Table 2]

[0159] Table 2 summarizes the type of resin curing product, the presence or absence of bisphenol A·2Na, and the purity of bisphenol A·2Na in Examples 1 to 4. From Table 2, it can be seen that bisphenol A·2Na can be obtained regardless of which resin curing product is used.

[0160] <Example 5> In a 1L four-necked flask equipped with a thermometer, stirrer, and condenser, 44g of solid a obtained in Example 1, 259g of epichlorohydrin, 100g of isopropanol, and 36g of water were charged. The mixture was heated to 40°C to dissolve uniformly, and then 38g of a 48.5% by mass sodium hydroxide aqueous solution was added dropwise over 90 minutes. Simultaneously with the addition, the temperature was raised from 40°C to 65°C over 90 minutes. The mixture was then held at 65°C for 30 minutes to complete the reaction. The reaction solution was transferred to a 1L separatory funnel, 69g of 65°C water was added, and the mixture was allowed to stand at 65°C for 1 hour. After standing, the aqueous phase was separated from the organic phase and the aqueous phase, and the by-product salt and excess sodium hydroxide were removed. Subsequently, epichlorohydrin was completely removed under reduced pressure at 150°C, 102g of methyl isobutyl ketone was added, and the temperature was raised to 65°C to dissolve it uniformly. Then, 1.4g of a 48.5% by mass aqueous sodium hydroxide solution was added and the mixture was reacted for 60 minutes. After the reaction, 57g of methyl isobutyl ketone was added to the reaction mixture, and the mixture was washed four times with 200g of water. Finally, epoxy resin A was obtained by completely removing the methyl isobutyl ketone under reduced pressure at 150°C.

[0161] According to JIS K 7236 (2009), the epoxy equivalent of the obtained epoxy resin A was measured and found to be 230 g / equivalent.

Claims

1. A method for producing metal phenoxide, comprising the following steps A to C. Step A: A step to decompose a thermosetting resin cured product and obtain a decomposition solution A containing metal phenoxide. Step B: A step in which only water is added to the decomposition liquid A obtained in Step A to obtain an oil-water two-phase liquid B. Step C: A process to obtain metal phenoxide by separating the oil-water two-phase liquid B obtained in Step B and recovering the aqueous phase.

2. The method for producing a metal phenoxide according to claim 1, wherein step C includes the following steps D to E. Step D: The oil-water two-phase liquid B obtained in Step B is separated into oil-water phases, and the resulting aqueous phase C is mixed with an organic solvent to obtain suspension D. Step E: A step in which the suspension D obtained in step D is subjected to solid-liquid separation to obtain metal phenoxide from the solid phase.

3. The method for producing a metal phenoxide according to claim 1, wherein step B is obtained by solid-liquid separation of the decomposition liquid A obtained in step A to remove insoluble matter to obtain decomposition liquid A', and water is added to the decomposition liquid A' to obtain an oil-water two-phase liquid B.

4. The method for producing a metal phenoxide according to claim 1, wherein the metal phenoxide is a metal alkoxide of a bisphenol compound.

5. The method for producing a metal phenoxide according to claim 4, wherein the bisphenol compound of the metal alkoxide of the bisphenol compound is 2,2-bis(4-hydroxyphenyl)propane.

6. The method for producing a metal phenoxide according to claim 1, wherein the metal of the metal phenoxide is an alkali metal.

7. A metal phenoxide obtained by the manufacturing method described in any one of claims 1 to 6, and Epiha A method for producing epoxy resin, comprising the step of reacting it with rohydrin.

8. A method for producing an epoxy resin, comprising the step of reacting an epoxy resin obtained by the manufacturing method described in claim 7 with a polyvalent hydroxy compound.

9. A method for producing a cured epoxy resin product, comprising the step of curing an epoxy resin composition containing an epoxy resin and a curing agent obtained by the manufacturing method described in claim 7.

10. A method for producing a cured epoxy resin product, comprising the step of curing an epoxy resin composition containing an epoxy resin and a curing agent obtained by the manufacturing method described in claim 8.

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