Method for the co-production of inorganic substances and phenolic compounds, and method for producing composite materials

Abstract

To provide a chemical recycle method which suppresses coloring of an obtained inorganic matter and thermosetting resin without giving a damage caused by corrosion to a decomposition tank.SOLUTION: A method for producing an inorganic matter and a phenolic compound simultaneously from a composite material containing the inorganic matter and a thermosetting resin cured product includes the following steps 1 to steps 4. Step 1: a step of bringing a composite material containing an inorganic matter and a thermosetting resin cured product into contact with a treatment liquid containing metal alkoxide and an organic solvent, and obtaining a decomposed liquid A containing the inorganic matter and the phenolic compound. Step 2: a step of carrying out solid-liquid separation of the decomposed liquid A obtained in the step 1 into a crude inorganic matter B and a dissolved liquid C containing the phenolic compound. Step 3: a step of cleaning the crude inorganic matter B obtained in the step 2, and obtaining an inorganic matter. Step 4: a step of separating the phenolic compound from the dissolved liquid C obtained in the step 2.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a method for co-producing an inorganic substance and a phenolic compound, and a method for producing a composite material.

Background Art

[0002] Epoxy resins are important materials used in various applications such as adhesives, insulating materials, paints, casting materials, and composite materials due to their excellent adhesiveness, electrical properties, and heat resistance. The cured epoxy resin obtained by curing this epoxy resin does not melt and is difficult to dissolve in general-purpose solvents. This is because the cured epoxy resin has a complex structure that is three-dimensionally crosslinked.

[0003] In view of recent carbon neutrality, chemical recycling that returns composite materials composed of cured thermosetting resins such as inorganic substances and epoxy resins to inorganic substances and monomer raw materials is required. Regarding inorganic carbon fibers, although methods for recycling them by thermal decomposition methods or dissolution methods are known, the method of returning them to monomer raw materials has been difficult due to the characteristics of the above-mentioned cured epoxy resin.

[0004] Methods for recovering glass fibers and carbon fibers, which are inorganic fiber materials, from composite materials composed of inorganic fiber materials and cured epoxy resins are known. For example, a method for obtaining glass fibers and carbon fibers, which are inorganic fiber materials, from a composite material composed of an inorganic fiber material and a cured epoxy resin using a cured epoxy resin decomposition catalyst and an organic solvent is known (Patent Document 1). Also, a method for decomposing and dissolving a cured epoxy resin and obtaining a cured epoxy resin again using the obtained recovered product is known. For example, a method for decomposing a cured epoxy resin, recovering the decomposition product, and using the obtained epoxy resin decomposition product as a curing agent to obtain a cured epoxy resin is known (Patent Document 2).

Prior Art Documents

Patent Documents

[0005] [Patent Document 1] Japanese Patent Publication No. 2001-172426 [Patent Document 2] International Publication No. 2017 / 154102 [Overview of the project]

[0006] In methods for recovering glass fibers and carbon fibers from composite materials consisting of inorganic fiber materials and epoxy resin curing products, the alkali metal compounds used as epoxy resin decomposition catalysts corrode stainless steel such as SUS304. Therefore, it was necessary to use high-grade, corrosion-resistant materials for the containers used to decompose the curing products. Furthermore, there was a problem that the metals leached out by this corrosion would contaminate the recovered glass fibers, carbon fibers, and phenolic compounds.

[0007] According to Example A1 of Patent Document 1, epoxy resin curing can be dissolved from composite materials using an alkali metal compound, which is a catalyst for decomposing epoxy resin curing, and an organic solvent. However, when the composite material was similarly decomposed using a decomposition tank made of stainless steel SUS304, significant corrosion was observed in the decomposition tank, the obtained glass fibers and carbon fibers showed discoloration derived from the dissolved metal, and the obtained bisphenol also showed discoloration. Furthermore, in a method of decomposing the epoxy resin curing product, recovering the decomposition products, and recycling the resulting epoxy resin decomposition products as a curing agent, the composition of the resulting epoxy resin decomposition products is Because it is an unknown chemical, it is difficult to stably produce epoxy resin cured products of the same quality, and there were safety concerns in the manufacturing process. Thus, further improvements were needed to chemically recycle composite materials industrially. [Means for solving the problem]

[0008] The inventors conducted diligent research to solve the above problems and found that by treating a composite material containing inorganic material and thermosetting resin with a treatment solution containing metal alkoxide, corrosion of the decomposition tank can be suppressed. Furthermore, they found that phenolic compounds can be selectively obtained by extracting them with water from the decomposition solution of the thermosetting resin curing product. They also found that an epoxy resin can be produced using the obtained phenolic compounds, and a composite material can be produced again using the epoxy resin and the inorganic material.

[0009] In other words, the present invention may include the following [1] to [5]. [1] A method for co-producing inorganic substances and phenolic compounds from a composite material containing an inorganic substance and a thermosetting resin cured product, comprising the following steps 1 to 4. Step 1: A composite material containing an inorganic substance and a thermosetting resin cured product is brought into contact with a treatment solution containing a metal alkoxide and an organic solvent to obtain a decomposition solution A containing an inorganic substance and a phenolic compound. Step 2: A process of solid-liquid separation of the decomposition solution A obtained in Step 1 into a dissolution solution C containing crude inorganic matter B and phenolic compounds. Step 3: A step to wash the crude inorganic material B obtained in Step 2 to obtain inorganic material. Step 4: A step to separate the phenol compound from the solution C obtained in Step 2. [2] The co-production method according to [1], wherein step 1 is carried out in a container containing stainless steel. [3] The co-production method according to [1] or [2], wherein the thermosetting resin cured product comprises an epoxy resin. [4] The co-production method according to any one of [1] to [3], wherein the inorganic material comprises one selected from the group consisting of carbon fibers and glass fibers. A reaction step of reacting a phenol compound obtained by any of the methods in [5][1] to [4] with epichlorohydrin, and A method for producing a composite material, comprising the step of curing an epoxy resin composition containing an epoxy resin and an inorganic substance obtained in the reaction step. [Effects of the Invention]

[0010] The present invention provides a chemical recycling method that suppresses discoloration of the resulting inorganic materials and thermosetting resins without causing corrosion damage to the decomposition tank. [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] One embodiment of the present invention is a method for producing inorganic substances and phenolic compounds together from a composite material containing an inorganic substance and a thermosetting resin cured product, comprising the following steps 1 to 4, which constitute a method for the co-production of inorganic substances and phenolic compounds. Step 1: A composite material containing inorganic material and thermosetting resin cured product is mixed with metal alkoxide and organic solvent. A process to obtain a decomposition solution A containing inorganic substances and phenolic compounds by contacting the substance with a processing solution containing a medium. Step 2: A process of solid-liquid separation of the decomposition solution A obtained in Step 1 into a dissolution solution C containing crude inorganic matter B and phenolic compounds. Step 3: A step to wash the crude inorganic material B obtained in Step 2 to obtain inorganic material. Step 4: A step to separate the phenol compound from the solution C obtained in Step 2.

[0013] In this specification, the term "co-production method" differs from methods that obtain only one of either inorganic substances or phenolic compounds from a composite material. It refers to a method in which inorganic substances such as carbon fibers are recovered through chemical recycling of the composite material, while also recovering phenolic compounds that serve as raw materials for thermosetting resins. In other words, it is a method that produces different products than methods that recover only inorganic substances through chemical recycling, or methods that recover only phenolic compounds through chemical recycling.

[0014] <Project 1> Project 1 is a process of obtaining a decomposition liquid A containing an inorganic substance and a phenolic compound by bringing a composite material containing an inorganic product into an inorganic substance and a thermosetting resin cured product into contact with a treatment liquid containing a metal alkoxide and an organic solvent. In the conventional method of dissolving a thermosetting resin cured product from a composite material using a treatment liquid containing an alkali metal compound, which is a decomposition catalyst for an epoxy resin cured product, and an organic solvent, significant corrosion was observed in the decomposition tank, and the obtained glass fibers and carbon fibers showed coloring derived from eluted metal, and the obtained bisphenol also showed coloring. In this embodiment, by using a metal alkoxide, it has become possible to suppress the corrosion of the decomposition tank.

[0015] The reason why the corrosion of the decomposition tank (stainless steel) can be suppressed by using a metal alkoxide is considered by the inventors that when hydroxide ions are present in the treatment liquid, they react with stainless steel and cause corrosion and thinning, and that such a reaction can be suppressed with an alkoxide.

[0016] (Composite material) The composite material to be decomposed contains an inorganic substance and a thermosetting resin cured product. The thermosetting resin is not particularly limited, and examples thereof include epoxy resins and phenolic resins. Among thermosetting resins, an epoxy resin is a resin having an epoxy group as a constituent element, and a phenolic resin is a resin having phenol, which is an aromatic compound, as a constituent element. The cured product made of the thermosetting resin may be composed of only one of these thermosetting resins or may be composed of two or more thermosetting resins.

[0017] The epoxy resin is not particularly limited, and examples thereof include 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 compound of biphenol, diglycidyl ether compound of naphthalene diol, diglycidyl ether compound of phenol compound, diglycidyl ether compound of alcohol compound, alkyl-substituted products thereof, halogenated products thereof, hydrogenated products thereof, etc. The epoxy resin may be used alone or in combination of two or more kinds.

[0018] Examples of the curing agents for these thermosetting resins include acid anhydrides, amine compounds, phenol compounds, isocyanate compounds, etc. The curing agent may be used alone or in combination of two or more kinds. The curing accelerator is not particularly limited, and examples thereof include alkali metal compounds, imidazole compounds, tertiary amine compounds, quaternary ammonium salts, organic phosphorus compounds, etc. The curing accelerator may be used alone or in combination of two or more kinds.

[0019] The inorganic substance is not particularly limited, and examples thereof include carbon, glass, metal, metal compounds, etc. Also, examples of the shape of the inorganic material include fibers, particles, foils, etc. The fibers may be in the form of non-woven fabric or woven fabric. In the case of woven fabric, it may be a cross material made by weaving fiber bundles, or a UD (Uni-Direction) material in which fiber bundles are arranged in one direction. The inorganic material may contain one kind alone or two or more kinds.

[0020] (Treatment liquid) The treatment liquid contains a metal alkoxide and an organic solvent. Metal alkoxides are compounds in which a hydrogen atom of the hydroxyl group of an alcohol is substituted with a metal, and can be obtained by adding a metal to an alcohol. The type of metal is not particularly limited as long as it can form a metal alkoxide, but alkali metals are preferred. Preferred alkali metals are sodium, lithium, and potassium, with sodium being more preferred. Other metals that can be used include magnesium and aluminum.

[0021] Furthermore, 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, and 1-hexanoyl Alcohol, 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 Examples include (-hydroxyethyl)-2-pyrrolidone, diacetone alcohol, 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, dipropylene glycol, etc. These alcohols may be used individually or in combination of two or more.

[0022] Metal alkoxides may be in solid or solution form. From the viewpoint of decomposition efficiency of thermosetting resin cured products, 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) are preferred as metal alkoxides.

[0023] These alkali metal alkoxides may be used individually or in combination of two or more.

[0024] The organic solvent is not particularly limited and includes alcohol-based solvents, ether-based solvents, aromatic solvents, etc.

[0025] The alcoholic solvent 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 Nol, 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)- Examples include 2-pyrrolidone, diacetone alcohol, 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. Alcoholic solvents may be used individually or in combination of two or more.

[0026] The ether solvent is not particularly limited and examples include 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.

[0027] Aromatic solvents are not particularly limited and include benzene, toluene, xylene, alkylbenzenes such as trimethylbenzene and ethylbenzene, and alkylnaphthalenes such as methylnaphthalene, ethylnaphthalene, and dimethylnaphthalene. Aromatic solvents may be used individually or in combination of two or more.

[0028] Furthermore, one or more alcohol-based solvents may be used in combination with one or more ether-based solvents, one or more alcohol-based solvents may be used in combination with one or more aromatic solvents, 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.

[0029] Of these, alcohol-based solvents are preferred because they exhibit excellent solubility of decomposition products of thermosetting resin cured products, and 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 used.

[0030] Furthermore, organic solvents are used in the processing of thermosetting resin cured products, as heating is required in the air. The organic solvent is preferably one with a boiling point of 100°C or higher under 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.

[0031] The processing solution may further contain other components besides metal alkoxides and organic solvents, as needed. Examples of other components include surfactants and low-viscosity solvents.

[0032] From the viewpoint of improving the decomposition efficiency of thermosetting resin curing products, the concentration of metal alkoxide in the treatment solution is preferably 0.001 moles to 100 moles, more preferably 0.005 moles to 50 moles, and particularly preferably 0.01 moles to 20 moles per liter of treatment solution. The higher the concentration of metal alkoxide, the more efficiently the thermosetting resin curing product can be decomposed. The lower the concentration of metal alkoxide, the more efficiently the thermosetting resin curing product can be decomposed without increasing the viscosity of the treatment solution.

[0033] When preparing the treatment solution, the metal alkoxide may be mixed with the organic solvent in a solid state or in a solution state. Heating is not required during the preparation of the treatment solution; it can be prepared by mixing the organic solvent and the metal alkoxide at room temperature (approximately 5-35°C).

[0034] (Processing method) When the composite material is brought into contact with the processing liquid, it is preferable to do so in a container containing stainless steel. 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. Preferably, it is austenitic stainless steel, and particularly preferably SUS304, SUS316, or SUS316L. By using the above-mentioned treatment solution, it is possible to suppress the corrosion of the container, and even when the composite material and the treatment solution come into contact in a container containing stainless steel, discoloration of the inorganic material and thermosetting resin obtained through chemical recycling can be suppressed.

[0035] The container, including stainless steel, is not particularly limited as long as it allows for contact between the composite material and the processing liquid. Any container that can be used as a decomposition tank may be box-shaped, cylindrical, mesh cage-shaped, or made of a porous material. From the viewpoint of dissolution efficiency, the ratio of the volume of composite material placed in the container to the volume of the container (filling rate) is preferably in the range of 5% to 25%.

[0036] The heating temperature of the processing solution used for contact 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.

[0037] The contact time should be sufficient for the thermosetting resin cured product to decompose and dissolve completely. This time varies depending on the type of thermosetting resin, the type and concentration of the metal alkoxide and organic solvent used, and the processing temperature. However, typically 2 to 50 hours is sufficient to decompose and dissolve 50% or more by weight of the thermosetting resin cured product.

[0038] <Process 2> Step 2 involves dissolving the decomposition solution A obtained in Step 1 into a solution containing crude inorganic material B and a phenolic compound. This is a process of separating the solid and liquid into a solution C. The method of solid-liquid separation 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.

[0039] <Process 3> Step 3 is the process of washing the crude inorganic material B obtained in Step 2 to obtain inorganic material. Cleaning is preferably carried out using at least one selected from the group consisting of organic solvents and water, and more preferably a combination of cleaning with an organic solvent and cleaning with water. Examples of organic solvents used for cleaning include alcohol-based solvents, ether-based solvents, and ketone-based solvents. In addition to pure water and distilled water, the water used for cleaning can be inorganic acids such as dilute hydrochloric acid, dilute sulfuric acid, dilute nitric acid, and phosphoric acid, or organic acids such as formic acid and acetic acid. Cleaning is preferably carried out for a sufficient amount of time to wash away the solvents of the decomposition solution adhering to the crude inorganic material B. For example, if the inorganic material is carbon fiber, it is preferable to clean it until its appearance is visually equivalent to commercially available carbon fiber.

[0040] <Step 4> Step 4 is the process of separating the phenol compound from the solution C obtained in Step 2. Since dissolving solution C contains many oil-soluble components in addition to phenol compounds, the phenol compounds can be recovered from the aqueous phase by performing oil-water separation. The method of separating oil and water is not particularly limited; after adding water such as pure water or distilled water to the dissolving solution C and mixing, the oil and water can be separated by methods such as separation using a permeable membrane, separation by specific gravity, or separation by centrifugation.

[0041] The phenol compound can be recovered from the aqueous phase separated in step 4. The phenol compound is not particularly limited, but a phenol compound that can react with epichlorohydrin to synthesize an epoxy resin is preferred. Bisphenol compounds are preferred as the phenol compound, and examples of bisphenol compounds include, but are not limited to, bisphenol A, bisphenol AP, bisphenol AF, bisphenol B, bisphenol BP, bisphenol C, bisphenol E, bisphenol F, bisphenol G, and bisphenol S.

[0042] Since the phenol compounds contained in the aqueous phase separated in step 4 are metal salts of phenol compounds, the phenol compounds can be precipitated by supplying an organic solvent that dissolves in water. Examples of organic solvents that dissolve in water include, but are not limited to, methanol, ethanol, propanol, isopropanol, butanol, isobutanol, dimethyl ether, diethyl ether, dipropyl ether, acetone, and methyl ethyl ketone. If the amount of organic solvent that dissolves in water is too small, the phenol compounds cannot be sufficiently precipitated, and if it is too large, the container becomes large and efficiency decreases. Therefore, the amount of organic solvent that dissolves in water supplied is preferably 0.001 to 1000, more preferably 0.01 to 100, and particularly preferably 0.05 to 10, relative to the weight of the aqueous phase separated in step 4. The temperature at which the organic solvent that dissolves in water is supplied is preferably below the boiling point of the organic solvent used, more preferably 70°C or below, and particularly preferably 50°C or below. The precipitated bisphenol compound can be recovered by solid-liquid separation using methods such as filtration, centrifugation, or decantation.

[0043] <Synthesis of epoxy resin> The invention relating to a method for producing a recycled epoxy resin using the bisphenol compound obtained in step 4 is also included in the disclosure of this specification. Furthermore, the obtained recycled epoxy resin may be further reacted with a polyvalent hydroxy compound raw material to produce a recycled epoxy resin. Thus, recycled epoxy resin can be produced using a bisphenol compound and / or a recycled epoxy resin produced using a bisphenol compound as at least a portion of the raw materials. The recycled epoxy resin of the present invention can be produced using known epoxy resin production methods without particular limitations, except that it uses a bisphenol compound (bisphenol obtained by the bisphenol production method of the present invention) and / or a recycled epoxy resin produced using a bisphenol compound as raw materials. For example, the bisphenol compound can be used as at least a portion of the polyvalent hydroxy compound raw materials when producing using a one-stage method, oxidation method, or two-stage method, as described later. The obtained recycled epoxy resin can also be used as at least a portion of the epoxy resin raw materials when producing using a two-stage method.

[0044] Furthermore, "epoxy resin raw material" refers to epoxy resin used as a raw material for recycled epoxy resin. "Polyvalent hydroxy compound" is a general term for phenolic compounds with a valency of 2 or higher and alcoholic compounds with a valency of 2 or higher, and "polyvalent hydroxy compound raw material" refers to polyvalent hydroxy compound used as a raw material for recycled epoxy resin.

[0045] The present invention can be used to produce the recycled epoxy resin using a one-step method, an oxidation method, a two-step method, and the like. The one-step method for producing recycled epoxy resin involves reacting a bisphenol compound (bisphenol obtained by the bisphenol production method of the present invention) with an epihalohydrin to obtain recycled epoxy resin. The method for producing recycled epoxy resin by oxidation involves allylation of a bisphenol compound using an allyl halide (such as allyl chloride or allyl bromide), followed by an oxidation reaction to obtain the recycled epoxy resin. The two-stage method for producing recycled epoxy resin involves reacting an epoxy resin raw material with a polyvalent hydroxy compound raw material, using a bisphenol compound and / or recycled epoxy resin as the raw materials.

[0046] The following describes methods for producing recycled epoxy resin using a one-stage method, an oxidation method, and a two-stage method.

[0047] (Method for producing recycled epoxy resin using a one-step method) The method for producing recycled epoxy resin using a one-step process is not particularly limited as long as it is a known manufacturing method, but it will be described in detail below.

[0048] The one-step method for producing recycled epoxy resin may also involve using a bisphenol compound in combination with a polyhydric hydroxy compound other than a bisphenol compound (hereinafter sometimes referred to as "other polyhydric hydroxy compounds"). In other words, the one-step method for producing recycled epoxy resin is a method of obtaining recycled epoxy resin by reacting a polyhydric hydroxy compound raw material with an epihalohydrin, and at least a portion of the polyhydric hydroxy compound raw material may be a bisphenol compound.

[0049] The bisphenol compound content in the polyhydric hydroxy compound raw material is not particularly limited, but a higher bisphenol compound content is environmentally friendly, so 1 to 100% by mass is preferred, and 10 to 100% by mass is more preferred.

[0050] Here, "other polyvalent hydroxy compounds" refers to a general term for phenol compounds with a valency of 2 or higher and alcohol compounds with a valency of 2 or higher, excluding bisphenol compounds. In the one-step method for producing recycled epoxy resin, the "polyvalent hydroxy compound raw material" is the total polyvalent hydroxy compound, which includes bisphenol compounds and other polyvalent hydroxy compounds used as needed.

[0051] 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, and various phenols mixed with benzaldehyde, hydroxybenzo Examples include polyhydric phenolic resins obtained by condensation reactions with various aldehydes such as benzoaldehyde, 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; ethylene glycol, trimethylene glycol, propylene glycol, linear aliphatic diols such as 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.

[0052] In the reaction, the polyvalent hydroxy compound raw material is dissolved in an epihalohydrin to form a homogeneous solution. Typically, epichlorohydrin or epibromohydrin is used as the epihalohydrin, but in the present invention, epichlorohydrin is preferred.

[0053] The amount of epihalohydrin used is preferably 1.0 to 14.0 equivalents, and particularly 2.0 to 10.0 equivalents, per equivalent of hydroxyl groups in the polyvalent hydroxy compound raw material (total polyvalent 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.

[0054] 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 hydroxyl groups in the polyvalent 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 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.

[0055] 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.

[0056] 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 a rapid reaction, alkali metal hydroxides are preferably added intermittently or continuously in small amounts over 0.1 to 24 hours, more preferably over 0.5 to 10 hours. If the addition time of alkali metal hydroxides exceeds the above lower limit, a rapid reaction will occur. This is preferable because it can prevent the reaction from proceeding and makes it easier to control the reaction temperature. It is also preferable that the addition time is below the above upper limit because it makes it easier to reduce the amount of polymer.

[0057] 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.

[0058] Furthermore, catalysts such as quaternary ammonium salts including tetramethylammonium chloride and tetraethylammonium bromide, tertiary amines including benzyldimethylamine and 2,4,6-tris(dimethylaminomethyl)phenol, imidazoles including 2-ethyl-4-methylimidazole and 2-phenylimidazole, phosphonium salts including ethyltriphenylphosphonium iodide, and phosphines including triphenylphosphine may also be used in this reaction.

[0059] Furthermore, in this reaction, inert organic solvents such as alcohols like ethanol and isopropanol, ketones like acetone, methyl ethyl ketone, and methyl isobutyl ketone, ethers like dioxane and ethylene glycol dimethyl ether, glycol ethers like methoxypropanol, and aprotic polar solvents like dimethyl sulfoxide and dimethylformamide may also be used.

[0060] [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.

[0061] 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.

[0062] 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.

[0063] 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.

[0064] 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.

[0065] As the alkali, solid or solution alkali metal hydroxides 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 dissolved in organic solvents or water. Preferably, alkali metal hydroxides are used as a solution dissolved in water or an organic solvent.

[0066] The amount of alkali metal hydroxide to be used is calculated on a solid content basis. 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 raw epoxy resin. 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.

[0067] 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 vacuum distillation and / or steam distillation.

[0068] (Method for producing recycled epoxy resin by oxidation) The method for producing recycled epoxy resin by oxidation is not particularly limited as long as it is a known production method, but it can be carried out according to the methods described in, for example, Japanese Patent Publication No. 2011-225711, Japanese Patent Publication No. 2012-092247, Japanese Patent Publication No. 2012-111858, etc.

[0069] In the method for producing regenerated epoxy resin by oxidation, similar to the one-step method, a bisphenol compound may be used in combination with other polyvalent hydroxy compounds other than bisphenol compounds. That is, the method for producing regenerated epoxy resin by oxidation involves allylation of a polyvalent hydroxy compound raw material using an allyl halogen, followed by an oxidation reaction to obtain the regenerated epoxy resin, and at least a portion of the polyvalent hydroxy compound raw material may be a bisphenol compound.

[0070] In the method for producing recycled epoxy resin by oxidation, the "polyvalent hydroxy compound raw material" is a total polyvalent hydroxy compound consisting of a bisphenol compound and other polyvalent hydroxy compounds used as needed. Other polyvalent hydroxy compounds include those used in the one-step method. The content of the bisphenol compound in the polyvalent hydroxy compound raw material is not particularly limited, but a higher content of bisphenol compound is environmentally friendly, so 1 to 100% by mass is preferred, and 10 to 100% by mass is more preferred.

[0071] (Method for producing recycled epoxy resin using a two-stage method) The method for producing recycled epoxy resin using a two-stage process is not particularly limited as long as it is a known manufacturing method, but it will be described in detail below.

[0072] A two-stage method for producing recycled epoxy resin may include a step of reacting an epoxy resin raw material with a polyvalent hydroxy compound raw material, wherein at least a portion of the epoxy resin raw material is recycled epoxy resin, and / or at least a portion of the polyvalent hydroxy compound raw material is a bisphenol compound.

[0073] In other words, the method for producing recycled epoxy resin using the two-step method is one of the following methods (i) to (iii).

[0074] Method (i): A method of reacting an epoxy resin other than recycled epoxy resin (hereinafter sometimes simply referred to as "other epoxy resin") with a polyhydric hydroxy compound raw material containing a bisphenol compound.

[0075] In method (i), the epoxy resin raw material is an epoxy resin other than recycled epoxy resin. The polyhydric hydroxy compound raw material is a total polyhydric hydroxy compound consisting of a bisphenol compound and other polyhydric hydroxy compounds used as needed.

[0076] Method (ii): An epoxy resin raw material containing recycled epoxy resin and a bisphenol compound Method for reacting polyvalent hydroxy compound starting materials.

[0077] In method (ii), the epoxy resin raw material is a total epoxy resin consisting of recycled epoxy resin and other epoxy resins used as needed. The polyhydric hydroxy compound raw material is a total polyhydric hydroxy compound consisting of a bisphenol compound and other polyhydric hydroxy compounds used as needed.

[0078] Method (iii): A method of reacting an epoxy resin raw material containing recycled epoxy resin with a polyhydric hydroxy compound other than a bisphenol compound.

[0079] In method (iii), the epoxy resin raw material is a total epoxy resin consisting of recycled epoxy resin and other epoxy resins used as needed. The polyhydric hydroxy compound raw material is a polyhydric hydroxy compound other than bisphenol compounds.

[0080] The recycled epoxy resins used in methods (ii) and (iii) can be obtained by a one-step method for producing recycled epoxy resins or by an oxidation method. Alternatively, the recycled epoxy resin obtained in method (i) may be used. Other epoxy resins are as described later in the method for producing cured recycled epoxy resins, and other polyvalent hydroxy compounds are the same as in the one-step method.

[0081] In methods (i) and (ii), the content of the bisphenol compound in the polyhydric hydroxy compound containing the bisphenol compound is not particularly limited, but a higher content of the bisphenol compound is more environmentally friendly, so 1 to 100% by mass is preferred, and 10 to 100% by mass is more preferred. Furthermore, in method (ii), the content of recycled epoxy resin in the epoxy resin raw material containing recycled epoxy resin 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.

[0082] 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. This equivalent ratio is preferable because it facilitates the development of high molecular weight and allows for the retention of more epoxy group terminals.

[0083] 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.

[0084] 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.

[0085] 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.

[0086] <Method for manufacturing recycled epoxy resin cured products> This specification also discloses an invention relating to a method for producing a cured recycled epoxy resin, wherein a recycled epoxy resin composition containing a recycled epoxy resin obtained by a method for producing recycled epoxy resin and a curing agent is cured to obtain a cured recycled epoxy resin product. In the method for producing a cured recycled epoxy resin of the present invention, the recycled epoxy resin obtained by the method for producing recycled epoxy resin described above is mixed with a curing agent to obtain a composition containing the recycled epoxy resin and the curing agent (hereinafter sometimes referred to as the "recycled epoxy resin composition"), and then the recycled epoxy resin composition is cured to obtain a cured recycled epoxy resin product.

[0087] Furthermore, the recycled epoxy resin composition may optionally contain other epoxy resins, curing agents, curing accelerators, inorganic fillers, coupling agents, etc., in addition to the recycled epoxy resin obtained by the method for producing recycled epoxy resin of the present invention.

[0088] The content of recycled epoxy resin in a recycled 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 content be 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 recycled epoxy resin composition. When other epoxy resins are included, the recycled epoxy resin content can be 40 to 99 parts by mass or 60 to 99 parts by mass, per 100 parts by mass of the total epoxy resin components in the recycled epoxy resin composition. Note that "total epoxy resin components" refers to the total amount of epoxy resin contained in the recycled epoxy resin composition, and is the sum of the recycled epoxy resin and other epoxy resins used as needed.

[0089] (Hardening agent) In this disclosure, "curing agent" refers to a substance that contributes to the crosslinking reaction and / or chain length extension reaction between epoxy groups of an epoxy resin. In this disclosure, even substances commonly referred to as "curing accelerators" will be considered curing agents if they contribute to the crosslinking reaction and / or chain length extension reaction between epoxy groups of an epoxy resin.

[0090] In the recycled epoxy resin composition, the content of the curing agent is preferably 0.1 to 1000 parts by mass per 100 parts by mass of the total epoxy resin component. More preferably, it is 500 parts by mass or less.

[0091] 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, aromatic amines and other amine-based curing agents, acid anhydride-based curing agents, amide-based curing agents, tertiary amines, imidazoles, etc. 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 components of the recycled epoxy resin obtained by the method for producing recycled epoxy resin of the present invention or other epoxy resins.

[0092] [Phenol-based curing agent] Specific examples of phenolic curing agents include bisphenol compounds, bisphenol A, tetramethylbisphenol A, bisphenol F, tetramethylbisphenol F, and bis Various polyhydric phenols such as phenol 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, brominated bisphenol A, brominated phenol novolac resin, and various other polyhydric phenols. Examples include polyhydric phenolic resins obtained by condensation reactions of phenols with various aldehydes such as benzaldehyde, hydroxybenzaldehyde, crotonaldehyde, and glyoxal; polyhydric phenolic resins obtained by condensation reactions of xylene resins with phenols; co-condensation resins of heavy oils or pitches with phenols and formaldehydes; various phenolic 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.

[0093] These phenolic curing agents may be used individually or in any combination and mixing ratio of two or more types.

[0094] 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 recycled epoxy resin composition.

[0095] [Amine-based curing agent] Examples of amine-based curing agents (excluding tertiary amines) include aliphatic amines, polyetheramines, alicyclic amines, and aromatic amines.

[0096] 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.

[0097] Examples of polyetheramines include triethylene glycol diamine, tetraethylene glycol diamine, diethylene glycol bis(propylamine), polyoxypropylenediamine, and polyoxypropylene triamines.

[0098] 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.

[0099] 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'-diamino-1,2-diphenylethane, 2,4-diaminodiphenylsulfone, 4,4'-diaminodiphenylsulfone, m-aminophenol, m-aminobenzylamine, and benzyldiamine. Examples include methylamine, 2-(dimethylaminomethyl)phenol, triethanolamine, methylbenzylamine, α-(m-aminophenyl)ethylamine, α-(p-aminophenyl)ethylamine, diaminodiethyldimethyldiphenylmethane, and α,α'-bis(4-aminophenyl)-p-diisopropylbenzene.

[0100] The amine-based curing agents listed above may be used individually or in any combination and mixing ratio of two or more types.

[0101] 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 recycled 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.

[0102] [Tertiary amines] 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.

[0103] 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 recycled 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.

[0104] [Acid anhydride curing agent] Examples of acid anhydride-based curing agents include acid anhydrides and modified acid anhydrides.

[0105] 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, methylhymic anhydride, trialkyltetrahydrophthalic anhydride, Examples include 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-naphthalenesuccinic acid dianhydride, and 1-methyl-dicarboxy-1,2,3,4-tetrahydro-1-naphthalenesuccinic acid dianhydride.

[0106] Examples of modified acid anhydrides include those obtained by modifying the aforementioned acid anhydrides with glycol. 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.

[0107] The acid anhydride-based curing agents listed above may be used individually or in any combination and proportion.

[0108] 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 recycled 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.

[0109] [Amid-based hardener] 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 recycled epoxy resin composition.

[0110] [Imidazoles] 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.

[0111] When using imidazoles, it is preferable that the amount of imidazoles in the recycled epoxy resin composition is 0.1 to 20% by mass relative to the total amount of all epoxy resin components and imidazoles.

[0112] [Other hardeners] In recycled epoxy resin compositions, other curing agents can be used in addition to the curing agent mentioned above. There are no particular restrictions on the other curing agents that can be used in recycled epoxy resin compositions; all curing agents that are generally known as epoxy resin curing agents can be used. These other hardening agents may be used individually or in combination of two or more.

[0113] (Other epoxy resins) The recycled epoxy resin composition may contain other epoxy resins (other epoxy resins) in addition to the recycled epoxy resin obtained by the method for producing recycled epoxy resin of the present invention. By including other epoxy resins, various physical properties can be improved.

[0114] Other epoxy resins that can be used in the recycled epoxy resin composition include all epoxy resins other than the epoxy resin contained in the recycled epoxy resin obtained by the method for producing recycled epoxy resin 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, dihydroxy Examples include epoxy resins derived from roxystilbenes, 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.

[0115] If the recycled 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.

[0116] (Curing accelerator) The recycled 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.

[0117] 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.

[0118] Phosphorus compounds that can be used as curing accelerators include organophosphines such as triphenylphosphine, diphenyl(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, alkyldiarylphosphine, or complexes of these organophosphines with organoborons, or complexes of these organophosphines with maleic anhydride, 1,4-benzoquinone, 2,5- Examples include quinone compounds such as ruquinone, 1,4-naphthoquinone, 2,3-dimethylbenzoquinone, 2,6-dimethylbenzoquinone, 2,3-dimethoxy-5-methyl-1,4-benzoquinone, 2,3-dimethoxy-1,4-benzoquinone, and phenyl-1,4-benzoquinone, as well as compounds obtained by adding compounds such as diazophenylmethane.

[0119] 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.

[0120] 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 recycled 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.

[0121] (Inorganic filler) Inorganic fillers can be added to recycled 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 recycled epoxy resin composition.

[0122] (Release agent) A mold release agent may be added to the recycled epoxy resin composition. Examples of mold 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 mold release agents such as paraffin. These may be used individually or in any combination and ratio of two or more types.

[0123] 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 recycled epoxy resin composition. This range of release agent addition is preferable because it allows for good release properties while maintaining curing characteristics.

[0124] [Coupling agent] A coupling agent may be added to the recycled epoxy resin composition. The coupling agent is preferably used in combination with an inorganic filler, as the addition of the coupling agent can improve the adhesion between the epoxy resin matrix and the inorganic filler. Examples of coupling agents include silane coupling agents and titanate coupling agents.

[0125] Examples of silane coupling agents include epoxysilanes such as γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, and β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane; aminosilanes such as γ-aminopropyltriethoxysilane, N-β(aminoethyl)γ-aminopropyltrimethoxysilane, N-β(aminoethyl)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 polymeric silanes of epoxy, amino, and vinyl types.

[0126] Examples of titanate coupling agents include isopropyltriisostearoyl titanate, isopropyltri(N-aminoethyl / aminoethyl) titanate, diisopropylbis(dioctyl phosphate) titanate, tetraisopropylbis(dioctyl phosphite) titanate, tetraoctylbis(ditridecyl phosphite) titanate, tetra(2,2-diallyloxymethyl-1-butyl)bis(ditridecyl) phosphite titanate, bis(dioctyl pyrophosphate) oxyacetate titanate, and bis(dioctyl pyrophosphate) ethylene titanate.

[0127] These coupling agents may be used individually, or two or more may be mixed in any combination and ratio.

[0128] When a coupling agent is used in a recycled 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. When 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, while when 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.

[0129] (Other ingredients) The recycled 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.

[0130] Examples of flame retardants include halogen-based flame retardants such as brominated epoxy resins and brominated phenolic 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.

[0131] (Curing method) A cured recycled epoxy resin product can be obtained by curing a recycled 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.

[0132] (Application) The cured recycled epoxy resin product obtained by curing the recycled epoxy resin composition has a low coefficient of thermal expansion and excellent heat crack resistance. Therefore, recycled 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 paint field, such as electrodeposition coatings for automobiles, heavy-duty anticorrosive coatings for ships and bridges, and coatings for the interior of beverage cans; in the electrical and electronic field, such as laminates, semiconductor encapsulants, insulating powder coatings, and coil impregnation; and in the civil engineering, construction, and adhesive fields, 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.

[0133] The recycled epoxy resin composition may be used after curing for the aforementioned applications, or it may be cured during the manufacturing process for those applications.

[0134] By preparing an epoxy resin composition containing the recycled epoxy resin and an inorganic substance, and curing the epoxy resin composition, it is possible to obtain a composite material again. In this way, the present invention can establish a new chemical recycling method. [Examples]

[0135] 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.

[0136] [Raw materials and reagents] The bisphenol A type epoxy resins (epoxy equivalents of 950 and 183) used were products of Mitsubishi Chemical Corporation. The ricacid (acid anhydride) M-700 used was a product of Shin Nippon Rika Co., Ltd. The curing catalyst used was a product of Shikoku Chemicals Co., Ltd. The 48% by mass aqueous sodium hydroxide solution, disylenediamide (DICY), 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU), hydrochloric acid, and toluene were all products of Fujifilm Wako Pure Chemical Industries, Ltd. The benzyl alcohol used was a product of Sankyo Chemical Co., Ltd. The carbon fiber used was 3mm carbon fiber chopped by Yoshino Co., Ltd. The glass fibers used were quartz wool manufactured by AS ONE Corporation.

[0137] [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

[0138] <Reference example 1: Thermosetting resin = CFRP preparation of acid anhydride cured product> Mixture 1 was obtained by thoroughly mixing 100g of bisphenol A type epoxy resin (epoxy equivalent 183), 100g of ricacid, and 1g of cuazole 2E4MZ in an aluminum cup. Mixture 2 was obtained by adding 100g of carbon fiber A (new) to the obtained mixture 1 and mixing. Carbon fiber composite material A was obtained by pouring the obtained mixture 2 into a flat mold, heating at 100°C for 3 hours, and then heating at 140°C for 3 hours.

[0139] <Reference example 2: GFRP preparation of thermosetting resin = acid anhydride cured product> In Reference Example 1, the procedure was carried out in the same manner as in Reference Example 1, except that 100g of quartz wool A was replaced with 100g of carbon fiber A, to obtain glass fiber composite material A.

[0140] <Reference Example 3: Preparation of CFRP using thermosetting resins (amine-cured products)> Mixture 3 was obtained by placing 100g of bisphenol A type epoxy resin (epoxy equivalent 183), 1g of DICY, and 1g of DCMU into an aluminum cup and mixing thoroughly. Mixture 4 was obtained by adding 100g of carbon fiber A to the obtained mixture 3 and mixing. Carbon fiber composite material B was obtained by pouring the obtained mixture 4 into a flat mold and heating at 150°C for 3 hours.

[0141] <Reference Example 4: Preparation of GFRP using thermosetting resins (amine-cured products)> Glass fiber composite material B was obtained by following the same procedure as in Reference Example 3, except that 100g of quartz wool A was substituted for 100g of carbon fiber A.

[0142] <Example 1> In a separable flask made of SUS304 stainless steel, equipped with a stirring blade, a condenser, and a thermometer, 1050 g of benzyl alcohol and 200 g of a methanol solution (basic compound) of 28% by mass of sodium methoxy were placed under a nitrogen atmosphere. The internal temperature was then gradually increased, and the methanol was removed by distillation to obtain 1100 g of the treatment solution. 1000g of the obtained processing solution was mixed with 200g of carbon fiber composite material A obtained in Reference Example 1 (inorganic material being carbon fiber, with a content of 66g; resin content of 134g). The mixture was then heated to 200°C over 1 hour at atmospheric pressure. The contents of the separable flask were maintained at 200°C for 3 hours to obtain slurry A containing carbon fibers. After lowering the temperature of the obtained slurry A to 70°C, the slurry A was filtered under reduced pressure to obtain crude carbon fibers and filtrate. No corrosion was observed on the inner surface of the SUS304 separable flask (the inner surface was silvery white). The obtained crude carbon fibers were thoroughly washed with acetone and water, and dried to recover 65g of carbon fiber B. The appearance of the recovered carbon fiber B was equivalent to that of carbon fiber A used in Reference Example 1, and no reddish tint was observed.

[0143] The obtained filtrate was placed in a glass jacketed separable flask equipped with a Liebig condenser, stirring blades, and a thermometer under a nitrogen atmosphere. 500 g of water was added and mixed. After standing, the mixture was allowed to stand to separate the oil and water, and the lower phase was removed from the separable flask to obtain aqueous phase 1. 500 g of water was added to the organic phase remaining in the separable flask and mixed. After standing, the mixture was allowed to stand to separate the oil and water, and the lower phase was removed from the separable flask to obtain aqueous phase 2. After placing the obtained aqueous phases 1 and 2 into a flask, the water was removed by evaporation under reduced pressure to obtain 500 g of aqueous solution. 3000 g of acetone was added to the obtained aqueous solution to obtain suspension A. Suspension A was filtered, and the filtrate was air-dried to obtain 75 g of white solid A. A portion of the obtained solid A was analyzed by high-performance liquid chromatography and found to contain 33% by mass of bisphenol A, with no other components observed.

[0144] <Comparative Example 1> 1000 g of benzyl alcohol and 80 g of a 48% by mass aqueous sodium hydroxide solution (basic compound) were placed in a SUS304 separable flask equipped with a stirring blade, condenser, and thermometer under a nitrogen atmosphere. After creating a full vacuum inside the separable flask, the internal temperature was gradually increased, and the water and some of the benzyl alcohol were removed by distillation to completely remove the water from the flask. By restoring the pressure inside the separable flask with nitrogen, 1070 g of the treated solution was obtained. 1000g of the obtained processing solution was mixed with 200g of carbon fiber composite material A obtained in Reference Example 1 (inorganic material being carbon fiber, with a content of 66g; resin content of 134g). The mixture was then heated to 200°C over 1 hour at atmospheric pressure. The contents of the separable flask were maintained at 200°C for 3 hours to obtain slurry A containing carbon fibers. After lowering the temperature of the obtained slurry A to 70°C, the slurry A was filtered under reduced pressure to obtain crude carbon fibers and filtrate. Corrosion was observed on the inner surface of the SUS304 separable flask, which had turned black. The obtained crude carbon fibers are thoroughly washed with acetone and water and dried to produce carbon fiber B6. 5g was recovered. The recovered carbon fiber B had a reddish appearance compared to carbon fiber A used in Reference Example 1.

[0145] The obtained filtrate was placed in a glass jacketed separable flask equipped with a Liebig condenser, stirring blades, and a thermometer under a nitrogen atmosphere. 500 g of water was added and mixed. After standing, the mixture was allowed to stand to separate the oil and water, and the lower phase was removed from the separable flask to obtain aqueous phase 1. 500 g of water was added to the organic phase remaining in the separable flask and mixed. After standing, the mixture was allowed to stand to separate the oil and water, and the lower phase was removed from the separable flask to obtain aqueous phase 2. After placing the obtained aqueous phases 1 and 2 into a flask, the water was removed by evaporation under reduced pressure to obtain 500 g of aqueous solution. 3000 g of acetone was added to the obtained aqueous solution to obtain a suspension. Suspension A was filtered, and the filtrate was air-dried to obtain 78 g of brown solid A. A portion of the obtained solid A was analyzed by high-performance liquid chromatography and found to contain 32% by mass of bisphenol A, with no other components observed.

[0146] Table 1 summarizes the types of basic compounds used in Example 1 and Comparative Example 1, the presence or absence of corrosion of the SUS304 separable flask and the color of its inner surface, and the color of the resulting solid. From Table 1, it can be seen that using metal alkoxides suppresses corrosion of the SUS304 separable flask and improves the color of the solid.

[0147] [Table 1] *1; Silvery white...◎, Slight discoloration...〇, Red discoloration...△, Black discoloration...× *2; Equivalent to carbon fiber A...◎, Slightly reddish...〇, Slightly reddish...△, Reddish...× *3; White - ◎, Yellow - ○, Brown - △, Reddish-brown - ×

[0148] <Example 2> In Example 1, the procedure was carried out in the same manner as in Example 1, except that 200g of glass fiber composite material A obtained in Reference Example 2 (inorganic material being glass, with a content of 66g and a resin content of 134g) was used instead of 200g of carbon fiber composite material A obtained in Reference Example 1 (inorganic material being carbon fiber, with a content of 66g and a resin content of 134g). No corrosion was observed in the SUS304 separable flask (the inner surface was silvery-white). Furthermore, the color of the recovered glass fibers was similar to that of quartz wool A. Additionally, the obtained solid material was white in color.

[0149] <Example 3> In Example 1, instead of 200g of carbon fiber composite material A obtained in Reference Example 1 (inorganic material is carbon fiber, with a content of 66g and resin content of 134g), the carbon fiber composite material obtained in Reference Example 3 was used. The procedure was carried out in the same manner as in Example 1, except that 200g of fiber composite material B (inorganic material being carbon fiber, with a content of 99g; resin content of 101g) was used. No corrosion was observed in the SUS304 separable flask (the inner surface was silvery-white). Furthermore, the color of the recovered carbon fibers was the same as that of carbon fiber A. Additionally, the obtained solid material was white in color.

[0150] <Example 4> In Example 1, the procedure was carried out in the same manner as in Example 1, except that 200g of glass fiber composite material B obtained in Reference Example 4 (inorganic material is glass, with a content of 99g and a resin content of 101g) was used instead of 200g of carbon fiber composite material A obtained in Reference Example 1 (inorganic material is carbon fiber, with a content of 66g and a resin content of 134g). No corrosion was observed in the SUS304 separable flask (the inner surface was silvery-white). Furthermore, the color of the recovered glass fibers was similar to that of quartz wool A. Additionally, the obtained solid material was white in color.

[0151] Table 2 summarizes the presence or absence of corrosion of the SUS304 separable flask, the color of the inner surface of the SUS304 separable flask, the appearance of the recovered inorganic material, and the color of the solid material in Examples 1 to 4. From Table 2, it can be seen that by using sodium methoxide as the basic compound, there was no corrosion of the SUS304 separable flask, the color of the inner surface of the SUS304 separable flask was good, the appearance of the recovered inorganic material was good, and the color of the solid material was also good.

[0152] [Table 2] *1; Silvery white...◎, Slight discoloration...〇, Red discoloration...△, Black discoloration...× *2; Equivalent to carbon fiber A...◎, Slightly reddish...〇, Slightly reddish...△, Reddish...× *3; White···◎, Yellow···○, Brown···△, Reddish-brown···×

[0153] <Example 5> In a 1L four-necked flask equipped with a thermometer, stirrer, and condenser, 40g of solid A obtained in Example 1, 240g 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. After that, the mixture was held at 65°C for 30 minutes to complete the reaction, and the reaction solution was transferred to a 1L separatory funnel. 70g of water at 65°C was added and the mixture was allowed to stand at 65°C for 1 hour. After standing, the aqueous phase was separated from the oil phase and the by-product salts and excess sodium hydroxide were removed. Then, epichlorohydrin was completely removed under reduced pressure at 150°C, 100g of methyl isobutyl ketone was added, and the temperature was raised to 65°C to dissolve it uniformly. After that, 1.5g of a 48.5% by mass aqueous sodium hydroxide solution was added and reacted for 60 minutes, then 60g of methyl isobutyl ketone was added and 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. According to JIS K7236 (2009), the epoxy equivalent of the obtained epoxy resin A was measured and found to be 228 g / equivalent.

[0154] Mixture 5 was obtained by placing 10g of epoxy resin A (epoxy equivalent 183), 80g of ricacid, and 0.1g of curazole 2E4MZ into an aluminum cup and mixing thoroughly. Mixture 6 was obtained by adding 10g of carbon fiber A (new) to the obtained mixture 5 and mixing. The obtained mixture 6 was poured into a flat mold and heated at 100°C for 3 hours, and then heated at 140°C for 3 hours to obtain carbon fiber composite material C.

Claims

1. A method for producing inorganic substances and phenolic compounds together by decomposing a composite material containing inorganic substances and thermosetting resin cured products in a container containing stainless steel, comprising the following steps 1 to 4. Step 1: A composite material containing an inorganic substance and a thermosetting resin cured product is brought into contact with a processing solution containing a metal alkoxide and an organic solvent in a container containing stainless steel to obtain a decomposition solution A containing an inorganic substance and a phenolic compound. Step 2: A process of solid-liquid separation of the decomposition solution A obtained in Step 1 into a dissolution solution C containing crude inorganic matter B and phenolic compounds. Step 3: A step to wash the crude inorganic material B obtained in Step 2 to obtain inorganic material. Step 4: A step to separate the phenol compound from the solution C obtained in Step 2.

2. The co-production method according to claim 1, wherein step 1 is carried out in a container containing stainless steel.

3. The co-production method according to claim 1, wherein the thermosetting resin cured product includes an epoxy resin.

4. The co-production method according to claim 1, wherein the inorganic material includes one or more selected from the group consisting of carbon fibers and glass fibers.

5. A reaction step of reacting a phenol compound obtained by any one of claims 1 to 4 with epichlorohydrin, and A method for producing a composite material, comprising the step of curing an epoxy resin composition containing an epoxy resin and an inorganic substance obtained in the reaction step.

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