Method for manufacturing inorganic substances, and method for manufacturing composite materials

Abstract

To provide improvement of inorganic liquid runoff, increased recovery of phenolic compounds from decomposed liquid, and efficient inorganic production methods, i.e., chemical recycling methods.SOLUTION: One form of the present invention is a method for producing an inorganic material from a composite material containing an inorganic material and a thermosetting resin cured material, comprising the following processes 1 to 4. Process 1: A composite material containing an inorganic material and a thermosetting resin cured material is brought into contact with treatment liquid containing an alkali metal compound to obtain decomposition liquid A containing the inorganic material. Process 2: The decomposition liquid A obtained in process 1 is neutralized to obtain neutralizing liquid B. Process 3: The neutralizing liquid B obtained in Process 2 is solid-liquid separated to obtain crude inorganic material C and separated liquid D. Process 4: The crude inorganic material C obtained in Process 3 is washed to obtain inorganic material.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a method for manufacturing an inorganic substance and a method for manufacturing 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 substances, although methods for recycling them by thermal decomposition methods or dissolution methods are known, the method of returning a cured epoxy resin to a monomer raw material has been difficult due to the characteristics of the cured epoxy resin described above.

[0004] A method for recovering carbon fibers, which are inorganic fiber materials, from a composite material composed of an inorganic fiber material and a cured epoxy resin is known. For example, a method for obtaining carbon fibers, which are inorganic fiber materials, from a composite material composed of an inorganic fiber material and a cured epoxy resin using a dissolution solution is known (Patent Document 1).

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] In a method for recovering carbon fibers, which are inorganic fiber material, from a composite material consisting of inorganic fiber material and epoxy resin curing, the viscosity of the dissolving solution increases because the solution is basic, and the amount of dissolving solution adhering to the inorganic fiber material increases. Therefore, there was a problem of significant loss of the recovered dissolving solution. Even if sufficient time for the solution to drain was allowed to reduce this loss, the high viscosity of the dissolving solution meant that it took a long time, making it not an efficient method.

[0007] According to Example 1 of Patent Document 1, carbon fibers can be recovered, but for the reasons mentioned above, a large amount of dissolving solution adheres to the carbon material, reducing the amount of bisphenol recovered from the dissolving solution. In addition, when recovering carbon fibers, the high viscosity of the dissolving solution makes it difficult to drain, which is a problem in handling the carbon fibers. Thus, further improvements were needed for the industrial chemical recycling of composite materials. The present invention aims to provide an efficient method for producing inorganic materials, i.e., a method for chemical recycling, by improving the liquid drainage of inorganic materials and increasing the amount of phenolic compounds recovered from the decomposition solution. [Means for solving the problem]

[0008] The inventors have conducted diligent studies to solve the above problems and have found that by neutralizing the decomposition solution after decomposing a composite material containing inorganic materials and thermosetting resin cured products, and before recovering the inorganic materials, the liquid separation of inorganic materials is improved, the amount of phenolic compounds recovered from the decomposition solution increases, and efficient inorganic materials are recovered. We discovered a method for recovering the material and phenolic compounds. Furthermore, we found a method for producing a composite material of inorganic materials and thermosetting resin cured products using the obtained inorganic materials and thermosetting resins.

[0009] In other words, the present invention may include the following [1] to [5]. [1] A method for producing an inorganic substance from a composite material containing an inorganic substance and a thermosetting resin cured product, comprising the following steps 1 to 4. Step 1: A process in which a composite material containing inorganic material and a thermosetting resin cured product is brought into contact with a treatment solution containing an alkali metal compound to obtain a decomposition solution A containing inorganic material. Step 2: A step to neutralize the decomposition solution A obtained in Step 1 to obtain neutralized solution B. Step 3: A step in which the neutralized liquid B obtained in Step 2 is subjected to solid-liquid separation to obtain crude inorganic matter C and separated liquid D. Step 4: A step to wash the crude inorganic material C obtained in Step 3 to obtain inorganic material. [2] The manufacturing method according to [1], wherein the inorganic material comprises one or more selected from the group consisting of carbon fibers and glass fibers. [3] The manufacturing method according to [1] or [2], wherein the thermosetting resin cured product includes an epoxy resin. [4] A manufacturing method according to any one of [1] to [3], further comprising step 5 below. Step 5: Step of recovering the phenol compound from the separated liquid D. A method for producing a composite material, comprising the step of curing a thermosetting resin composition containing an inorganic substance obtained by any of the methods described in [5] [1] to [4] and a thermosetting resin. [Effects of the Invention]

[0010] The present invention improves the liquid drainage of inorganic materials, increases the amount of phenolic compounds recovered from the decomposition solution, and provides an efficient method for producing inorganic materials, i.e., a method for chemical recycling. [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 an inorganic substance from a composite material containing an inorganic substance and a thermosetting resin cured product, the method comprising the following steps 1 to 4. Step 1: A process in which a composite material containing inorganic material and a thermosetting resin cured product is brought into contact with a treatment solution containing an alkali metal compound to obtain a decomposition solution A containing inorganic material. Step 2: A step to neutralize the decomposition solution A obtained in Step 1 to obtain neutralized solution B. Step 3: A step in which the neutralized liquid B obtained in Step 2 is subjected to solid-liquid separation to obtain crude inorganic matter C and separated liquid D. Step 4: A step to wash the crude inorganic material C obtained in Step 3 to obtain inorganic material. The following step 5 may also be included. Step 5: Step of recovering the phenol compound from the separated liquid D.

[0013] <Process 1> Step 1 is a step in which a composite material containing an inorganic substance and a thermosetting resin cured product is brought into contact with a treatment solution containing an alkali metal compound to obtain a decomposition solution A containing an inorganic substance.

[0014] (composite material) The composite materials subject to decomposition include inorganic materials and thermosetting resin cured products. Thermosetting resins are not particularly limited and include, for example, epoxy resins and phenolic resins. Among thermosetting resins, epoxy resins are resins that have epoxy groups as a constituent, and phenolic resins are resins that have phenol, an aromatic compound, as a constituent. That is the case. The cured product made from the thermosetting resin may consist of only one of these thermosetting resins, or it may consist of two or more thermosetting resins.

[0015] 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 novolak type epoxy resin, cresol novolak type epoxy resin, bisphenol A novolak 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.

[0016] 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.

[0017] 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.

[0018] (Treatment liquid) The treatment solution contains alkali metal compounds and organic solvents. Examples of alkali metal compounds include alkali metal hydrides, hydroxides, borohydrides, amide compounds, fluorides, chlorides, bromides, iodides, borates, phosphates, carbonates, sulfates, nitrates, organic acid salts, alkoxides, phenolates, and alkoxides. One alkali metal compound may be used alone, or two or more may be used in combination. Of these, sodium hydroxide, potassium hydroxide, sodium methoxide, sodium ethoxide, potassium methoxide, and potassium ethoxide are preferred due to their industrial availability.

[0019] The organic solvent is not particularly limited and includes alcohol-based solvents, ether-based solvents, aromatic solvents, etc.

[0020] 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 Sanol, 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, dipropylene glycol, etc. Alcoholic solvents may be used individually or in combination of two or more.

[0021] 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.

[0022] 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.

[0023] 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.

[0024] Of these, alcohol-based solvents are preferred because they exhibit excellent solubility of decomposition products of thermosetting resin cured products.

[0025] Furthermore, from the viewpoint of requiring heating in the processing step 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.

[0026] The treatment solution may further contain other components besides alkali metal compounds and organic solvents, as needed. Examples of other components include surfactants and low-viscosity solvents.

[0027] From the viewpoint of improving the decomposition efficiency of thermosetting resin curing products, the concentration of alkali metal compounds in the treatment solution is preferably 0.001 mol to 100 mol per liter of treatment solution, more preferably 0.005 mol to 50 mol, and particularly preferably 0.01 mol to 20 mol. The higher the concentration of alkali metal compounds, the more efficiently the thermosetting resin curing products can be decomposed. The lower the concentration of alkali metal compounds, the more efficiently the thermosetting resin curing products can be decomposed without increasing the viscosity of the treatment solution.

[0028] When preparing the treatment solution, the alkali metal compound may be mixed with the organic solvent in a solid state, or in a solution state.

[0029] When the composite material is brought into contact with the processing solution, the heating temperature of the processing 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 modification of the solvent and decomposition products, this temperature is preferably 300°C or lower, and particularly preferably 250°C or lower.

[0030] 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 alkali metal compound 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. The container used for the contact treatment is not particularly limited as long as it allows the composite material and the treatment liquid to come 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 material is also not particularly limited, but it is preferable that the container contains stainless steel. 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%.

[0031] <Process 2> Step 2 is the process of neutralizing the decomposition solution A obtained in Step 1 to obtain neutralized solution B. In conventional methods, because the dissolving solution is basic, the viscosity of the dissolving solution increases, and the amount of dissolving solution adhering to the inorganic material increases. This resulted in a problem of significant loss of the recovered dissolving solution. Even if sufficient time for the solution to drain was allowed to reduce this loss, it still took a long time due to the high viscosity of the dissolving solution. However, by neutralizing the decomposition solution, the viscosity is reduced, and the drainage of the inorganic material is improved.

[0032] The acid used for neutralization is not particularly limited and includes acetic acid, formic acid, hydrochloric acid, sulfuric acid, nitric acid, and phosphoric acid. When neutralizing by mixing acids, it is preferable to ensure that the pH of neutralization solution B is 10 or less, and more preferably 8 or less. Furthermore, the viscosity of neutralizing solution B is preferably 5 mPa·s or less, and more preferably 3 mPa·s or less, from the viewpoint of preventing inorganic substances from draining.

[0033] <Process 3> Step 3 is a process of solid-liquid separation of the neutralized liquid B obtained in Step 2 to obtain crude inorganic material C and separated liquid D. 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.

[0034] <Step 4> Step 4 is the process of washing the crude inorganic material C obtained in Step 3 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 C. 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.

[0035] <Process 5> Step 5 is the step of recovering the phenol compound from the separated liquid D. Since the separated liquid D 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 separation liquid D 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.

[0036] The phenol compound can be recovered from the aqueous phase separated in step 5. 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.

[0037] <Manufacturing process for composite materials> The inorganic material obtained in step 4 above can be mixed with a thermosetting resin and cured to obtain a composite material again. The thermosetting resin may also be synthesized from the phenol compound obtained in step 5 above. For example, the phenol compound obtained in step 5 can be reacted with epichlorohydrin to produce an epoxy resin. Furthermore, an epoxy resin composition containing the epoxy resin and the inorganic material can be prepared, and the epoxy resin composition can be cured to obtain a composite material again. Thus, the present invention establishes a new method of chemical recycling. [Examples]

[0038] 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.

[0039] [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.

[0040] [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 analysis time 0 minutes, Solution A:Solution B = 30:70 (volume ratio, the same applies below). Analysis time 0-2 The ratio of solution A to solution B was gradually increased to 100:0 over 5 minutes. ·Flow rate: 0.40mL / min • Detection wavelength: 280nm

[0041] <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.

[0042] <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.

[0043] <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. The obtained mixture 3 was poured into a flat mold and heated at 150°C for 3 hours to obtain carbon fiber composite material B.

[0044] <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.

[0045] <Example 1> 1100 g of benzyl alcohol and 80 g of a 48% by mass sodium hydroxide aqueous solution were placed in a 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. 1040 g of the treated solution was obtained by restoring the pressure inside the separable flask with nitrogen. To 1000g of the resulting treatment solution, add 200g of carbon fiber composite material A obtained in Reference Example 1 (inorganic materials are...). It contains carbon fiber, with a content of 66g. The resin content is 134g. After adding (the substance), leave it at atmospheric pressure for 1 hour. The mixture was heated to 200°C. 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, it was neutralized with hydrochloric acid. The neutralized solution was filtered by gravity using filter paper placed on a glass funnel, yielding 90g of crude carbon fibers and a filtrate on the filter paper. The filtration rate was very good. The ease of handling of the obtained crude carbon fibers was also very good. The obtained crude carbon fibers were thoroughly washed with acetone and water, and then dried to recover 60g of carbon fibers.

[0046] The obtained filtrate was placed in a jacketed separable flask equipped with a Liebig condenser, stirring blades, and a thermometer under a nitrogen atmosphere. After standing, oil-water separation was performed to obtain organic phase 1. 550 g of 5% by mass aqueous sodium hydroxide solution was added to the obtained organic phase 1 and mixed. After standing, oil-water separation was performed, and the lower phase was withdrawn 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, oil-water separation was performed, and the lower phase was withdrawn from the separable flask to obtain aqueous phase 2. In a jacketed separable flask equipped with a Liebig condenser, stirring blades, and a thermometer, 200 g of toluene was added to the obtained aqueous phases 1 and 2 under a nitrogen atmosphere and mixed, and the internal temperature was raised to 80°C. While maintaining the internal temperature at 80°C, the aqueous phase was neutralized with hydrochloric acid. After that, it was allowed to stand. The oil-water phase was separated, and aqueous phase 3 was extracted to obtain organic phase 2. 200g of water was added to the obtained organic phase 2 and mixed while maintaining the internal temperature at 80°C. After standing, the oil-water phase was separated again, and aqueous phase 4 was extracted to obtain organic phase 3. The obtained organic phase 3 was cooled to 10°C to obtain a slurry. The obtained slurry was filtered off by vacuum filtration to obtain a cake. Using an evaporator equipped with an oil bath, the entire cake was dried at an oil bath temperature of 85°C, 15 Torr, for 3 hours to obtain 26g of solid. The obtained solid was confirmed to be bisphenol A by high-performance liquid chromatography, and its purity was 99%.

[0047] <Comparative Example 1> 1000 g of benzyl alcohol and 80 g of a 48% by mass sodium hydroxide aqueous solution were placed in a 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. To the 1070g of processed liquid obtained, 200g of carbon fiber composite material A obtained in Reference Example 1 (inorganic material) was added. It contains carbon fiber, with a content of 66g. The resin content is 134g. After adding (the substance), leave it at atmospheric pressure for 1 hour. The temperature was raised to 200°C. The contents of the separable flask were maintained at 200°C for 3 hours. A slurry A containing carbon fibers was obtained. The temperature of the obtained slurry A was lowered to 70°C. The obtained liquid was filtered by gravity using filter paper placed on a glass funnel, yielding 153g of crude carbon fibers and a filtrate on the filter paper. The filtration rate was very poor. The handling of the obtained crude carbon fibers was also very poor, as the liquid dripped. The obtained crude carbon fibers were thoroughly washed with acetone and water, and then dried to recover 59g of carbon fibers.

[0048] The obtained filtrate was placed in a jacketed separable flask equipped with a Liebig condenser, stirring blades, and a thermometer under a nitrogen atmosphere. After standing, oil-water separation was performed to obtain organic phase 1. 550 g of 5% by mass aqueous sodium hydroxide solution was added to the obtained organic phase 1 and mixed. After standing, oil-water separation was performed, and the lower phase was withdrawn 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, oil-water separation was performed, and the lower phase was withdrawn from the separable flask to obtain aqueous phase 2. In a jacketed separable flask equipped with a Liebig condenser, stirring blades, and a thermometer, 200 g of toluene was added to the obtained aqueous phases 1 and 2 under a nitrogen atmosphere and mixed, and the internal temperature was raised to 80°C. While maintaining the internal temperature at 80°C, the aqueous phase was neutralized with hydrochloric acid. After standing, oil-water separation was performed, and aqueous phase 3 was extracted to obtain organic phase 2. 200 g of water was added to the obtained organic phase 2 and mixed while maintaining the internal temperature at 80°C. After standing, oil-water separation was performed, and aqueous phase 4 was extracted to obtain organic phase 3. The obtained organic phase 3 was cooled to 10°C to obtain a slurry. The obtained slurry was filtered by vacuum filtration to obtain a cake. Using an evaporator equipped with an oil bath, the entire cake was dried at an oil bath temperature of 85°C, 15 Torr, for 3 hours to obtain 20 g of solid. The obtained solid was identified as bisphenol A by high-performance liquid chromatography, and its purity was 99%.

[0049] Table 1 summarizes the presence or absence of neutralization of slurry A, the amount and ease of handling of crude carbon fibers obtained, the filtration rate on filter paper, and the amount of bisphenol A obtained in Example 1 and Comparative Example 1. From Table 1, it can be seen that neutralizing slurry A greatly improves the filtration rate on filter paper and also improves the amount of bisphenol A recovered. This result is due to the fact that neutralization reduces the viscosity of the obtained liquid, thereby reducing the amount of liquid contained in the crude carbon fibers. Furthermore, by reducing the viscosity of the obtained liquid, the crude carbon fibers become much easier to handle and the filtration performance is also very good, so it can be seen that inorganic materials such as carbon fibers and bisphenol can be efficiently obtained.

[0050] [Table 1] *1 ◎...Because the viscosity of the slurry was low, it was possible to easily place the slurry containing crude carbon fibers onto the filter paper. ×...Because the viscosity of the slurry was high, it was difficult to place the slurry containing crude carbon fibers onto the filter paper. *2 ◎···Filtration completed within 3 minutes, ○···Filtration completed within 3-5 minutes, △···Filtration completed within 5-10 minutes, ×···Requires more than 10 minutes to complete filtration

[0051] <Example 2> In Example 1, 200g of carbon fiber composite material A obtained in Reference Example 1 (inorganic material is carbon fiber) was used. The content is 66g. The resin content is 134g. Instead of the gas obtained in Reference Example 2, Lath fiber composite material A 200g (Inorganic material is glass, content is 66g. Resin content is 13g) The procedure was carried out in the same manner as in Example 1, except that 4g of ( ) was used. The amount of crude glass fibers obtained was 91 g. The handling of the crude glass fibers was very good. Furthermore, the filtration rate of the liquid obtained by neutralization through filter paper was also very good. The amount of bisphenol A obtained was 27 g.

[0052] <Example 3> In Example 1, 200g of carbon fiber composite material A obtained in Reference Example 1 (inorganic material is carbon fiber) was used. The content is 66g. The resin content is 134g.) Instead of the carbon obtained in Reference Example 3, Fiber composite material B 200g (Inorganic material is carbon fiber, content is 99g. Resin content is 10 The procedure was carried out in the same manner as in Example 1, except that 1 g of (amount) was used. The amount of crude carbon fiber obtained was 95 g. The handling of the crude carbon fiber was very good. Furthermore, the filtration rate of the liquid obtained by neutralization through filter paper was also very good. The amount of bisphenol A obtained was 23 g.

[0053] <Example 4> In Example 1, 200g of carbon fiber composite material A obtained in Reference Example 1 (inorganic material is carbon fiber) was used. The content is 66g. The resin content is 134g. Instead of the gas obtained in Reference Example 4, Lath fiber composite material B 200g (The inorganic material is glass fiber, with a content of 99g. The resin content is...) The procedure was carried out in the same manner as in Example 1, except that 101g of ( ) was used. The amount of crude glass fiber obtained was 92 g. The crude glass fiber was very easy to handle. Furthermore, the filtration rate of the liquid obtained by neutralization through filter paper was also very good. The amount of bisphenol A obtained was 22 g.

[0054] Table 2 summarizes the presence or absence of neutralization of slurry A, the amount and ease of handling of the obtained crude inorganic fibers, the filtration rate using filter paper, and the amount of bisphenol A obtained in Examples 1 to 4. From Table 2, it can be seen that by neutralizing slurry A, inorganic materials, which are inorganic fibers, and bisphenol can be efficiently obtained even when the composite material changes.

[0055] [Table 2] *1 ◎...Because the viscosity of the slurry was low, it was possible to easily place the slurry containing crude carbon fibers onto the filter paper. ×...Because the viscosity of the slurry was high, it was difficult to place the slurry containing crude carbon fibers onto the filter paper. *2 ◎···Filtration completed within 3 minutes, ○···Filtration completed within 3-5 minutes, △···Filtration completed within 5-10 minutes, ×···Requires more than 10 minutes to complete filtration

[0056] <Example 5> In a 1L four-necked flask equipped with a thermometer, stirrer, and condenser, 50g of bisphenol A, 260g of epichlorohydrin, 100g of isopropanol, and 40g of water obtained in Examples 1 and 2 were charged. The mixture was heated to 40°C to dissolve uniformly, and then 40g of a 48% by mass aqueous sodium hydroxide 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 oil phase and the aqueous phase was removed, and the by-product salts and excess sodium hydroxide were removed. The epichlorohydrin was then completely removed under reduced pressure at 150°C. Next, 110 g of methyl isobutyl ketone was added, and the temperature was raised to 65°C to dissolve it uniformly. Then, 2 g of 48% by mass sodium hydroxide aqueous solution was added and reacted for 60 minutes. After that, 60 g of methyl isobutyl ketone was added and washed four times with 200 g of water. Subsequently, methyl isobutyl ketone was completely removed under reduced pressure at 150°C to obtain the epoxy resin of Example 5. According to JIS K7236 (2009), the epoxy equivalent of the obtained epoxy resin was measured and found to be 185 g / equivalent.

[0057] Mixture 5 was obtained by placing 50g of the epoxy resin (epoxy equivalent 185), 50g of ricacid, and 0.5g of cuazole 2E4MZ into an aluminum cup and mixing thoroughly. Mixture 6 was obtained by adding 50g of the carbon fiber obtained in Example 1 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 an inorganic substance from a composite material containing an inorganic substance and a thermosetting resin cured product, comprising the following steps 1 to 4. Step 1: A process in which a composite material containing an inorganic substance and a thermosetting resin cured product is brought into contact with a treatment solution containing an alkali metal compound to obtain a decomposition solution A containing an inorganic substance. Step 2: A step to neutralize the decomposition solution A obtained in Step 1 to obtain neutralized solution B. Step 3: A step in which the neutralized liquid B obtained in Step 2 is subjected to solid-liquid separation to obtain crude inorganic matter C and separated liquid D. Step 4: A step to wash the crude inorganic material C obtained in Step 3 to obtain inorganic material.

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

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

4. The manufacturing method according to claim 1, further comprising the following step 5. Step 5: Step of recovering the phenol compound from the separated liquid D.

5. A method for producing a composite material, comprising the step of curing a thermosetting resin composition comprising an inorganic substance obtained by the method according to any one of claims 1 to 4 and a thermosetting resin.

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