Method for producing isopropenylphenol-containing solution, method for producing bisphenol A-containing solution, method for producing bisphenol A, and method for producing polycarbonate resin

Abstract

To provide a method for producing isopropenylphenol-containing solution which enables efficient removal of a coloring component derived from polycarbonate resin, and enables simple recovery of isopropenylphenol, and to produce bisphenol A having excellent color tone by using the isopropenylphenol-containing solution.SOLUTION: A method for producing an isopropenylphenol-containing solution is provided, including: a step (A1) of decomposing polycarbonate resin (PC), thereby obtaining coarse solution a1 including a low-boiling point component and bisphenol A; a step (A2) of distilling the low-boiling point component from the coarse solution a1 obtained in the step (A1), thereby obtaining coarse solution a2 containing the bisphenol A; and a step (A3) of distilling the coarse solution a2 while or after decomposing the bisphenol A included in the coarse solution a2 obtained in the step (A2), and recovering a distillate a3 including isopropenylphenol and phenol.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for producing an isopropenylphenol-containing solution and a method for producing a bisphenol A-containing solution. More specifically, the present invention relates to a method for producing these solutions by utilizing the decomposition of polycarbonate resin. The present invention also relates to a method for producing bisphenol A using the bisphenol A-containing solution obtained by the method for producing a bisphenol A-containing solution. Furthermore, the present invention relates to a method for producing a polycarbonate resin using bisphenol A obtained by the method for producing bisphenol A. [Background technology]

[0002] Plastic is easily accessible, durable, and inexpensive, leading to its mass production not only in Japan but around the world. Because much of this plastic is "disposable," it is not properly disposed of and some ends up in the environment. Specifically, plastic waste flows from rivers into the ocean, where it degrades due to waves and ultraviolet light, becoming smaller than 5 mm. These tiny pieces of plastic waste are called microplastics. Animals and fish accidentally ingest these microplastics. Plastic waste thus has a significant impact on ecosystems, and in recent years, the marine plastic problem has become a global concern. Polycarbonate resin, used in a wide range of fields due to its transparency, mechanical properties, flame retardancy, dimensional stability, and electrical properties, is no exception.

[0003] One known method for recycling polycarbonate resin is chemical recycling, in which polycarbonate resin is chemically decomposed back to bisphenol A for reuse. Chemical recycling of polycarbonate resin is important as one of the means to solve the marine plastic problem. Polycarbonate resin can be decomposed by various methods such as hydrolysis and alcoholysis, and the resulting bisphenol A can be recovered by crystallization, etc.

[0004] It is also known that bisphenol A obtained by decomposing polycarbonate resin can be incorporated into the following general bisphenol A production process and purified together to obtain high-purity bisphenol A. [General manufacturing process of bisphenol A] Step 1: A step of reacting acetone with phenol in the presence of an acidic catalyst to obtain a reaction solution containing bisphenol A Step 2: A step of distilling and separating the reaction liquid obtained in step 1 to obtain a concentrated liquid. Step 3: A step of crystallizing and recovering the concentrated liquid obtained in step 2 to obtain adduct crystals and mother liquor. Step 4: Producing bisphenol A from the adduct crystals

[0005] For example, a method is known in which a crude solution containing low-purity bisphenol A recovered from decomposition products obtained by thermally or chemically decomposing waste plastics is supplied to a concentrated liquid or mother liquor obtained in the following general bisphenol A production process (Patent Document 1).

[0006] Also known is a method in which waste polycarbonate is decomposed into isopropenylphenol and the like, and the resulting product is supplied to step 1 (reaction step) of the general bisphenol A production process (Patent Document 2). [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-112781 [Patent Document 2] Japanese Patent Application Laid-Open No. 2006-36668 Summary of the Invention [Problem to be solved by the invention]

[0008] Bisphenol A is also used as a raw material for optical materials such as optical polycarbonate resin. Optical materials require excellent color tone (transparency), so the raw material bisphenol A must also have excellent color tone.

[0009] However, due to impurities derived from polycarbonate resin, it has not been easy to achieve bisphenol A obtained by decomposing polycarbonate resin with the same quality as bisphenol A produced from petroleum-derived acetone and phenol. Even if the bisphenol A obtained by hydrolysis or alcoholysis of polycarbonate resin is highly pure, if small amounts of coloring components derived from the polycarbonate resin remain, it may not be sufficient as a raw material for optical materials that require excellent color tone (transparency).

[0010] As described above, it is known that bisphenol A obtained by decomposing polycarbonate resin is supplied to a conventional bisphenol A production process and purified together to obtain high-purity bisphenol A. For example, according to Example 1 of Patent Document 1, a compact disk made of polycarbonate resin is first alcoholyzed with cyclohexanol, and a heavy fraction that does not distill is obtained after vacuum distillation. The heavy fraction that does not distill is then mixed with a mother liquor obtained by crystallization in a conventional bisphenol A production process, and further mixed with a reaction product containing bisphenol A obtained by a condensation reaction in a conventional bisphenol A production process, and concentrated. The resulting concentrated liquid is crystallized, followed by solid-liquid separation to obtain bisphenol A-phenol adduct crystals, and phenol is then distilled off from the resulting adduct crystals to obtain high-purity bisphenol A.

[0011] However, even if the resulting bisphenol A is highly pure, the color tone may be deteriorated due to the influence of coloring components contained in the heavy fraction derived from the polycarbonate resin that is not distilled.

[0012] Also known is a method of alkaline decomposition of polycarbonate resin to decompose it into isopropenylphenol. For example, according to Example 1 of Patent Document 2, a known method is used to decompose polycarbonate resin into isopropenylphenol, and the resulting decomposition liquid is supplied to a BPA synthesis step in which bisphenol A is synthesized. The method describes that the synthesis liquid containing bisphenol A obtained in the BPA synthesis step is supplied to a concentration step in a bisphenol A production step, and high-purity bisphenol A can be obtained by a conventional method.

[0013] The inventors have found that in order to decompose polycarbonate resin into isopropenylphenol, it is necessary to carry out the decomposition at a high temperature, and that in addition to the decomposition reaction of the polycarbonate resin, condensation reactions of the generated isopropenylphenol and the like occur, making the reactions complex. Therefore, it has been found that it is not easy to recover isopropenylphenol.

[0014] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method for producing an isopropenylphenol-containing solution, which can efficiently remove colored components derived from polycarbonate resin and can easily recover the produced isopropenylphenol.

[0015] An object of the present invention is to provide a method for producing a bisphenol A-containing solution using the obtained isopropenylphenol-containing solution.

[0016] An object of the present invention is to provide a method for producing bisphenol A using the obtained isopropenylphenol-containing solution or bisphenol A-containing solution.

[0017] A further object of the present invention is to provide a method for producing a polycarbonate resin using the obtained bisphenol A. [Means for solving the problem]

[0018] As a result of intensive research aimed at solving the above problems, the present inventors have discovered a method in which polycarbonate resin is first decomposed to obtain bisphenol A, low-boiling components are distilled off, and then the bisphenol A is further decomposed and distilled to obtain isopropenylphenol. They have also discovered a method in which the obtained isopropenylphenol is recombined in the presence of an acid catalyst to obtain bisphenol A. They have also discovered a method in which the obtained bisphenol A is recycled to a bisphenol A production process to produce bisphenol A. They have also discovered a method for producing polycarbonate resin using the obtained bisphenol A. That is, the present invention relates to the following inventions.

[0019] <1> A step (A1) of decomposing a polycarbonate resin to obtain a crude solution a1 containing low-boiling components and bisphenol A; a step (A2) of distilling off the low-boiling components from the crude solution a1 obtained in the step (A1) to obtain a crude solution a2 containing bisphenol A; a step (A3) of distilling the crude solution a2 obtained in the step (A2) while or after decomposing bisphenol A contained in the crude solution a2, and recovering a distillate a3 containing isopropenylphenol and phenol; A method for producing an isopropenylphenol-containing solution comprising: <2> 2. The method for producing an isopropenylphenol-containing solution according to claim 1, wherein the distillate a3 in the step (A3) contains isopropenylphenol in an amount of 1.0 mass % or more and 59 mass % or less. <3> The temperature at which the polycarbonate resin is decomposed in the step (A1) is 150°C or lower. <1> or <2> A method for producing the isopropenylphenol-containing solution described in <4> The temperature for decomposing bisphenol A in the step (A3) is higher than 150°C and lower than 250°C. <1> from <3> 10. A method for producing an isopropenylphenol-containing solution according to any one of the preceding claims. <5> The distillation in the step (A3) is carried out while extracting a part of the non-volatile liquid from the system. <1> from <4> 10. A method for producing an isopropenylphenol-containing solution according to any one of the preceding claims.

[0020] <6> The aforementioned <1> from <5> 1. A method for producing a bisphenol A-containing solution, comprising contacting a distillate a3 obtained by any one of the methods described above with an acid catalyst to recombine isopropenylphenol and phenol to produce bisphenol A, thereby obtaining a reaction solution a4 containing bisphenol A.

[0021] <7> The aforementioned <6> 1. A method for producing bisphenol A, comprising the step (A5) of purifying the reaction solution a4 obtained by the method for producing a bisphenol A-containing solution according to claim 1, to obtain bisphenol A. <8> a step (B1) of dehydrating and condensing acetone and phenol in the presence of an acid catalyst to obtain a reaction liquid b1 containing bisphenol A; a step (B2) of distilling off unreacted acetone and water from the reaction liquid b1 obtained in the step (B1) to obtain a concentrated liquid b2; a step (B3) of crystallizing the concentrated liquid b2 obtained in the step (B2) to obtain a slurry liquid, and subjecting the slurry liquid to solid-liquid separation to separate it into a mother liquid b3 and a cake containing crystals of an adduct of bisphenol A and phenol; a step (B4) of purifying the cake obtained in the step (B3) to obtain bisphenol A; a step (B6A) of distilling the mother liquor b3 obtained in the step (B3) while or after decomposing bisphenol A contained in the mother liquor b3, and recovering a distillate b6 containing isopropenylphenol and phenol; a step (B7) of contacting the distillate b6 with an acid catalyst to recombine isopropenylphenol and phenol to produce bisphenol A, thereby obtaining a reaction solution b7 containing bisphenol A; and a portion of the mother liquor b3 obtained in the step (B3) is circulated and supplied to the step (B1) and / or the step (B2); A method for producing bisphenol A, comprising supplying the reaction liquid b7 obtained in the step (B7) to the step (B1) and / or the step (B2), The aforementioned <6> A method for producing bisphenol A, comprising supplying the reaction liquid a4 obtained by the method for producing a bisphenol A-containing solution described in the above to one or more steps selected from the group consisting of the step (B1), the step (B2), and the step (B3). <9> a step (B1) of dehydrating and condensing acetone and phenol in the presence of an acid catalyst to obtain a reaction liquid b1 containing bisphenol A; a step (B2) of distilling off unreacted acetone and water from the reaction liquid b1 obtained in the step (B1) to obtain a concentrated liquid b2; a step (B3) of crystallizing the concentrated liquid b2 obtained in the step (B2) to obtain a slurry liquid, and subjecting the slurry liquid to solid-liquid separation to separate it into a mother liquid b3 and a cake containing crystals of an adduct of bisphenol A and phenol; a step (B4) of purifying the cake obtained in the step (B3) to obtain bisphenol A; a step (B5) of isomerizing the mother liquor b3 obtained in the step (B3), followed by crystallization and solid-liquid separation to separate the mother liquor b5 and a cake containing crystals of an adduct of bisphenol A and phenol; a step (B6B) of distilling the mother liquor b5 obtained in the step (B5) while or after decomposing bisphenol A contained in the mother liquor b5, and recovering a distillate b6 containing isopropenylphenol and phenol; a step (B7) of contacting the distillate b6 with an acid catalyst to recombine isopropenylphenol and phenol to produce bisphenol A, thereby obtaining a reaction solution b7 containing bisphenol A; and a portion of the mother liquor b3 obtained in the step (B3) is circulated and supplied to the step (B1) and / or the step (B2); A method for producing bisphenol A, comprising supplying the reaction liquid b7 obtained in the step (B7) to the step (B1) and / or the step (B2), The aforementioned <6> A method for producing bisphenol A, comprising supplying the reaction liquid a4 obtained by the method for producing a bisphenol A-containing solution described in the above to one or more steps selected from the group consisting of the step (B1), the step (B2), and the step (B3). <10> the reaction liquid a4 is mixed with one or more selected from the group consisting of the reaction liquid b1, the concentrated liquid b2, the mother liquid b3, and the reaction liquid b7, and the mixture is supplied to one or more steps selected from the group consisting of the step (B1), the step (B2), and the step (B3); <8> or <9> The method for producing bisphenol A described in <11> a step (B1) of dehydrating and condensing acetone and phenol in the presence of an acid catalyst to obtain a reaction liquid b1 containing bisphenol A; a step (B2) of distilling off unreacted acetone and water from the reaction liquid b1 obtained in the step (B1) to obtain a concentrated liquid b2; a step (B3) of crystallizing the concentrated liquid b2 obtained in the step (B2) to obtain a slurry liquid, and subjecting the slurry liquid to solid-liquid separation to separate it into a mother liquid b3 and a cake containing crystals of an adduct of bisphenol A and phenol; a step (B4) of purifying the cake obtained in the step (B3) to obtain bisphenol A; a step (B6A) of distilling the mother liquor b3 obtained in the step (B3) while or after decomposing bisphenol A contained in the mother liquor b3, and recovering a distillate b6 containing isopropenylphenol and phenol; a step (B7) of contacting the distillate b6 with an acid catalyst to recombine isopropenylphenol and phenol to produce bisphenol A, thereby obtaining a reaction solution b7 containing bisphenol A; and a portion of the mother liquor b3 is recycled and supplied to the step (B1) and / or the step (B2); The reaction liquid b7 is supplied to the step (B1) and / or the step (B2), The aforementioned <1> from <5> 1. A method for producing bisphenol A, comprising supplying the distillate a3 obtained by the method for producing an isopropenylphenol-containing solution according to any one of the above to the step (B7). <12> a step (B1) of dehydrating and condensing acetone and phenol in the presence of an acid catalyst to obtain a reaction liquid b1 containing bisphenol A; a step (B2) of distilling off unreacted acetone and water from the reaction liquid b1 obtained in the step (B1) to obtain a concentrated liquid b2; a step (B3) of crystallizing the concentrated liquid b2 obtained in the step (B2) to obtain a slurry liquid, and subjecting the slurry liquid to solid-liquid separation to separate it into a mother liquid b3 and a cake containing crystals of an adduct of bisphenol A and phenol; a step (B4) of purifying the cake obtained in the step (B3) to obtain bisphenol A; a step (B5) of isomerizing the mother liquor b3 obtained in the step (B3), followed by crystallization and solid-liquid separation to separate the mother liquor b5 and a cake containing crystals of an adduct of bisphenol A and phenol; a step (B6B) of distilling the mother liquor b5 obtained in the step (B5) while or after decomposing bisphenol A contained in the mother liquor b5, and recovering a distillate b6 containing isopropenylphenol and phenol; a step (B7) of contacting the distillate b6 with an acid catalyst to recombine isopropenylphenol and phenol to produce bisphenol A, thereby obtaining a reaction solution b7 containing bisphenol A; and a portion of the mother liquor b3 is recycled and supplied to the step (B1) and / or the step (B2); The reaction liquid b7 is supplied to the step (B1) and / or the step (B2), The aforementioned <1> from <5> 1. A method for producing bisphenol A, comprising supplying the distillate a3 obtained by the method for producing an isopropenylphenol-containing solution according to any one of the above to the step (B7). <13> The distillate a3 is mixed with the distillate b6 and supplied to the step (B7). <11> or <12> The method for producing bisphenol A described in <14> The aforementioned <7> from <13> 1. A method for producing a polycarbonate resin, comprising obtaining bisphenol A through the method for producing bisphenol A according to any one of the above items 1 to 5, and then using the bisphenol A to produce a polycarbonate resin. [Effects of the Invention]

[0022] According to the present invention, there is provided a method for producing an isopropenylphenol-containing solution, which can efficiently remove colored components derived from polycarbonate resin and can also easily recover the produced isopropenylphenol.

[0023] According to the present invention, there is provided a method for producing a bisphenol A-containing solution using the obtained isopropenylphenol-containing solution.

[0024] According to the present invention, there is provided a method for producing bisphenol A using the obtained isopropenylphenol-containing solution or bisphenol A-containing solution. By using the isopropenylphenol-containing solution or bisphenol A-containing solution, bisphenol A with a good color tone can be obtained.

[0025] Furthermore, according to the present invention, there is provided a method for producing a polycarbonate resin using the obtained bisphenol A. [Brief explanation of the drawings]

[0026] [Figure 1] FIG. 1 is a flow chart showing an example of a method for producing an isopropenylphenol-containing solution of the present invention. [Figure 2] FIG. 1 is a flow chart showing an example of a method for producing a bisphenol A-containing solution according to the present invention. [Figure 3] FIG. 1 is a flow chart showing an example of the method for producing bisphenol A of the present invention. [Figure 4] FIG. 1 is a flow chart showing an example of the method for producing bisphenol A of the present invention. [Figure 5] FIG. 1 is a flow chart showing an example of the method for producing bisphenol A of the present invention. [Figure 6] FIG. 1 is a flow chart showing an example of the method for producing bisphenol A of the present invention. [Figure 7] FIG. 1 is a flow chart showing an example of the method for producing bisphenol A of the present invention. [Figure 8] FIG. 1 is a flow chart showing an example of the method for producing bisphenol A of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0027] The following describes in detail an embodiment of the present invention, but the description of the constituent elements described below is one example of an embodiment of the present invention, and the present invention is not limited to the following description as long as it does not deviate from the gist of the present invention. Note that when the expression "to" is used in this specification, it is used as an expression that includes the numerical values ​​or physical property values ​​before and after it.

[0028] <Method of producing isopropenylphenol-containing solution> Fig. 1 is a flow chart showing an example of the method for producing an isopropenylphenol-containing solution of the present invention. Each step of the method for producing an isopropenylphenol-containing solution of the present invention will be described below with reference to Fig. 1.

[0029] The method for producing an isopropenylphenol-containing solution shown in FIG. 1 includes a step (A1) of decomposing a polycarbonate resin (PC) to obtain a crude solution a1 containing low-boiling components and bisphenol A, a step (A2) of distilling off the low-boiling components from the crude solution a1 obtained in the step (A1) to obtain a crude solution a2 containing bisphenol A, and a step (A3) of distilling the crude solution a2 obtained in the step (A2) while or after decomposing the bisphenol A contained in the crude solution a2 to recover a distillate a3 containing isopropenylphenol (IPP) and phenol (PHL).

[0030] As a result of investigations by the present inventors, it has been found that decomposing a polycarbonate resin into isopropenylphenol and phenol in one step causes the following problems. Phenol can be recovered, but the recovery rate of isopropenylphenol is low. - The recovery rate of decomposition products derived from the carbonate units of polycarbonate resin is low. -It is difficult to remove the residue from the reactor after decomposition and distillation. The reason for this is thought to be that in order to directly convert polycarbonate resin into isopropenylphenol and phenol, a decomposition reaction must be carried out at high temperatures, and the high temperatures cause complex reactions that inhibit the desired reaction.

[0031] The method for producing an isopropenylphenol-containing solution of the present invention involves decomposing a polycarbonate resin into bisphenol A, and then decomposing the bisphenol A into isopropenylphenol and phenol in a stepwise manner. This allows the initial decomposition reaction to be carried out under mild conditions, and side reactions can be suppressed.

[0032] Alternatively, after decomposition to bisphenol A, low-boiling components are distilled off and a reaction is carried out to decompose bisphenol A into isopropenylphenol and phenol. This allows for the production of highly reactive isopropenylphenol after removing many of the components that can react with isopropenylphenol as low-boiling components, and makes it possible to suppress side reactions of isopropenylphenol.

[0033] Waste plastics containing polycarbonate resin may contain stabilizers derived from polycarbonate resin, resins other than polycarbonate resin, sebum, dust, foreign matter, etc. These may cause discoloration, and if incorporated into the process for producing bisphenol A from acetone and phenol described below, they may cause contamination and impair the quality of the resulting bisphenol A. In the method for producing an isopropenylphenol-containing solution of the present invention, after decomposing polycarbonate resin into bisphenol A, low-boiling components are distilled off, and the isopropenylphenol and phenol produced by the decomposition of bisphenol A are recovered by distillation, thereby removing impurities that cause discoloration. As a result, the resulting isopropenylphenol-containing solution can be used to produce bisphenol A with excellent color tone.

[0034] [Process (A1)] The step (A1) is a step of decomposing a polycarbonate resin to obtain a crude solution a1 containing low-boiling components and bisphenol A.

[0035] (Polycarbonate resin (PC)) The polycarbonate resin used in step (A1) includes a bisphenol A-type polycarbonate resin containing repeating units (sometimes simply referred to as "repeating units") derived from bisphenol A (2,2-bis(4-hydroxyphenyl)propane).

[0036] Furthermore, the polycarbonate resin may be not only a bisphenol A-type polycarbonate resin containing a repeating unit derived from bisphenol A alone, but also a composition containing a resin other than polycarbonate resin, such as a copolymer or polymer alloy. Examples of compositions containing a resin other than polycarbonate resin include polycarbonate / polyester copolymers, polycarbonate / polyester alloys, polycarbonate / polyarylate copolymers, and polycarbonate / polyarylate alloys. When using a composition containing a resin other than polycarbonate resin, it is preferable to use one in which bisphenol A-type polycarbonate resin is the main component (the composition contains 50% by mass or more of bisphenol A-type polycarbonate resin).

[0037] Furthermore, the polycarbonate resin may be a mixture of two or more different polycarbonate resins.

[0038] From the viewpoint of chemical recycling, the polycarbonate resin is preferably a polycarbonate resin contained in waste plastics. Polycarbonate resins are molded and used into various molded products such as optical components such as headlamps and optical recording media such as optical disks. As waste plastics containing polycarbonate resins, offcuts, defective products, used molded products, etc., generated when molding polycarbonate resins into these molded products can be used.

[0039] Waste plastics may be used after appropriate cleaning, crushing, pulverization, etc. Methods for crushing waste plastics include coarse crushing using a jaw crusher or rotary crusher to crush to 20 cm or less, medium crushing using a rotary crusher, cone crusher, or mill to crush to 1 cm or less, and milling to crush to 1 mm or less. It is sufficient to reduce the size of the waste plastics to a size that can be fed to the decomposition tank. Furthermore, if the waste plastic is thin plastic, such as CDs or DVDs, it can be shredded using a shredder or the like and fed to the decomposition tank. Furthermore, portions made of components other than polycarbonate resin, such as other resins in copolymers or polymer alloys, or the surface and back layers of optical disks, may be removed in advance before use.

[0040] (Decomposition of polycarbonate resin) The polycarbonate resin can be decomposed by any known method. For example, the polycarbonate resin is decomposed by heating the polycarbonate resin in a solvent to obtain a crude solution a1 containing bisphenol A.

[0041] The solvent used for decomposing the polycarbonate resin is not particularly limited, but examples thereof include aromatic alcohols such as phenol, xylenol, and cresol; aliphatic alcohols such as methanol, ethanol, and butanol; water; aromatic hydrocarbons such as toluene; dialkyl carbonates such as dimethyl carbonate, diethyl carbonate, and dibutyl carbonate; and alkyl esters such as butyl acetate, dimethyl malonate, and ethylene diacetate.

[0042] Among these, it is preferable to use phenol for decomposing polycarbonate resin because the dissolution rate of polycarbonate resin is high. That is, it is preferable to decompose polycarbonate resin in a solvent containing phenol to produce bisphenol A.

[0043] The phenol-containing solvent may contain solvents other than phenol, but preferably contains phenol as the main component. For example, the mass of phenol in the phenol-containing solvent is preferably 50 mass% or more, and can be appropriately set to 65 mass% or more, 70 mass% or more, 75 mass% or more, 80 mass% or more, 85 mass% or more, 90 mass% or more, etc., depending on the types of other solvents and catalysts.

[0044] Furthermore, compared with the case where phenol is used alone as a solvent, the decomposition rate of the polycarbonate resin is improved, and the polycarbonate resin can be decomposed even under mild conditions (for example, atmospheric pressure, about 60 to 150°C). Therefore, the phenol-containing solvent is preferably a mixed solvent containing phenol and any solvent selected from the group consisting of water, monohydric alcohols, and dihydric alcohols, and more preferably a mixed solvent containing phenol and water or a mixed solvent containing phenol and a monohydric alcohol. As the monohydric alcohol, a linear alcohol having 1 to 5 carbon atoms, such as methanol, ethanol, or n-butanol, is preferred.

[0045] Also preferred is a method of producing bisphenol A by decomposing a polycarbonate resin in a solvent containing a dialkyl carbonate. The solvent containing a dialkyl carbonate may contain a solvent other than the dialkyl carbonate, for example, a mixed solvent containing a dialkyl carbonate and a monohydric alcohol. The amount of dialkyl carbonate in the solvent containing a dialkyl carbonate can be appropriately set to 50% by mass or more, 55% by mass or more, 60% by mass or more, 65% by mass or more, 70% by mass or more, etc., depending on the types of other solvents and catalysts, etc.

[0046] It is preferable to use a catalyst for decomposing the polycarbonate resin. The catalyst is not particularly limited, and a basic catalyst or an acid catalyst can be used.

[0047] The basic catalyst is preferably any one selected from the group consisting of alkali metal hydroxides, alkali metal carbonates, alkali metal oxides, alkali metal alkoxides, alkylamines, and pyridines.

[0048] The alkali metal hydroxide is preferably sodium hydroxide or potassium hydroxide.

[0049] Examples of alkali metal carbonates include sodium carbonate, sodium hydrogen carbonate, potassium carbonate, and potassium hydrogen carbonate, with sodium carbonate or potassium carbonate being preferred.

[0050] Examples of alkali metal oxides include sodium oxide and potassium oxide.

[0051] Examples of alkali metal alkoxides include aliphatic alkoxides such as sodium methoxide, sodium ethoxide, potassium methoxide, potassium ethoxide, and potassium t-butoxide; and aromatic alkoxides such as sodium phenoxide and potassium phenoxide.

[0052] Alkylamines are compounds having an amine structure in which at least one hydrogen atom of ammonia is substituted with an alkyl group. Examples of alkylamines include alkyl monoamines such as methylamine, ethylamine, propylamine, dimethylamine, diethylamine, trimethylamine, and triethylamine, and alkyl diamines such as ethylenediamine, trimethylenediamine, tetramethylenediamine, pentaemethylenediamine, hexaemethylenediamine, N-methylethylenediamine, N,N'-dimethylethylenediamine, N,N'-dimethyltrimethylenediamine, N,N,N',N'-tetramethylethylenediamine, N,N'-diethylethylenediamine, N,N,N',N'-tetraethylethylenediamine, 1,3-diaminopropane, N-methyl-1,3-diaminopropane, N,N'-dimethyl-1,3-diaminopropane, and N,N,N',N'-tetramethyl-1,3-diaminopropane. The alkylamine is preferably a secondary amine or a tertiary amine, more preferably a tertiary amine.

[0053] The boiling point of the alkylamine is preferably 200° C. or lower, more preferably 160° C. or lower. The lower limit is preferably 10° C. or higher, more preferably 30° C. or higher. If the boiling point is within this range, the alkylamine can be removed from the system together with the solvent when part of the solvent is distilled off by vacuum distillation or the like.

[0054] The pyridine may be unsubstituted or may have a substituent such as a methyl group or a hydroxyl group, and is preferably unsubstituted pyridine.

[0055] The acid is preferably any one selected from the group consisting of hydrochloric acid, sulfuric acid, phosphoric acid, and sulfonic acid, including alkylsulfonic acids such as methanesulfonic acid and aromatic sulfonic acids such as toluenesulfonic acid.

[0056] The molar ratio of catalyst to 1 mole of repeating units of polycarbonate resin ((mass [g] of catalyst used / molecular weight [g / mol] of catalyst) / (mass [g] of polycarbonate resin used / molecular weight of repeating units [g / mol])) can be appropriately set depending on the type of catalyst. The molar ratio of catalyst to 1 mole of repeating units of polycarbonate resin is preferably 0.0001 or more, more preferably 0.0005 or more, and even more preferably 0.0007 or more. If the amount of catalyst used relative to the polycarbonate resin is small, the decomposition rate tends to slow, the decomposition time tends to increase, and the efficiency tends to deteriorate. In addition, the molar ratio of catalyst to 1 mole of repeating units of polycarbonate resin can be 4.5 or less, 4.0 or less, 3.0 or less, 2.0 or less, 1 or less, 0.9 or less, 0.8 or less, etc. If the amount of catalyst used relative to the polycarbonate resin used is large, the production efficiency tends to decrease.

[0057] The temperature for decomposing polycarbonate resin (PC) can be set appropriately depending on the type of solvent used, etc., but is preferably 150°C or lower. If the temperature for decomposing polycarbonate resin is too high, the decomposition products derived from the carbonate units and the solvent tend to evaporate, and equipment such as a reflux device is required to prevent them from distilling out of the system, which is undesirable. The temperature for decomposing PC may be 130°C or lower, 120°C or lower, 110°C or lower, 100°C or lower, or 95°C or lower. Furthermore, if the temperature for decomposing PC is too low, the decomposition of PC will be insufficient, so the temperature is preferably 60°C or higher, more preferably 70°C or higher, more preferably 75°C or higher, and even more preferably 80°C or higher.

[0058] The pressure for the decomposition reaction of PC is preferably 1 kPa to 50 MPa, more preferably 5 kPa to 10 MPa.

[0059] The reaction method for the decomposition reaction of polycarbonate resin is not particularly limited, and may be continuous or batchwise. For example, in the case of a batchwise method, the reaction time for decomposing the polycarbonate resin is appropriately selected depending on the concentration of the polycarbonate resin, the decomposition temperature, the pressure, etc., but since a long reaction time tends to decompose the produced bisphenol A, it is preferably 30 hours or less, and the smaller the value, the more preferable in the order of 25 hours or less, 20 hours or less, 15 hours or less, 10 hours or less, and 5 hours or less. Furthermore, since a short reaction time may not sufficiently progress the decomposition reaction, it is preferably 0.1 hours or more, more preferably 0.5 hours or more, and even more preferably 1 hour or more.

[0060] (crude solution a1) The crude solution a1 contains bisphenol A produced by the decomposition of the polycarbonate resin, the solvent and catalyst used in the decomposition of the polycarbonate resin, low-boiling components such as by-products derived from carbonate units, and incomplete decomposition products such as dimers and trimers of bisphenol A. The crude solution a1 is a composition that is liquid under the temperature conditions in which steps (A1) and (A2) are performed. The low-boiling components refer to components with a boiling point lower than that of phenol. The low-boiling components vary depending on the solvent and catalyst used in the decomposition of the polycarbonate resin, but examples include water, aliphatic alcohols, aromatic hydrocarbons, amines, by-produced carbon dioxide, by-produced dialkyl carbonates, etc.

[0061] [Process (A2)] Step (A2) is a step of distilling off low-boiling components from the crude solution a1 obtained in step (A1) to obtain a crude solution a2 containing bisphenol A. By removing the low-boiling components, it is possible to suppress side reactions of the produced isopropenylphenol in step (A3).

[0062] The low-boiling components can be removed by distillation at a temperature of 50 to 200°C and a pressure of 0.1 to 150 kPa.

[0063] Distillation is preferably carried out so that crude solution a2 is 70% by mass or less of crude solution a1, more preferably 60% by mass or less, and even more preferably 50% by mass or less. If the amount of low-boiling components distilled off is too small, there is a problem that when bisphenol A is decomposed in step 3, the low-boiling components boil, preventing the temperature from rising to the desired temperature. Furthermore, distillation is preferably carried out so that crude solution a2 is 20% by mass or more of crude solution a1, and more preferably 30% by mass or more. If crude solution a1 is concentrated too much, there is a problem that bisphenol A precipitates and crude solution a1 solidifies.

[0064] When the polycarbonate resin is decomposed in a solvent containing phenol in step (A1), it is preferable to distill off a portion of the phenol in step (A2), which allows low-boiling components having a boiling point lower than that of phenol to be efficiently distilled off.

[0065] The crude solution a1 may be neutralized or washed as appropriate depending on the catalyst used, etc., and then distilled.

[0066] (crude solution a2) Crude solution a2 is a composition that contains bisphenol A and is liquid at the temperature conditions for step (A3). Crude solution a2 may be solid at a temperature lower than the temperature conditions for step (A3). Since crude solution a2 is usually transferred to the apparatus for performing step (A3) at 40°C or higher, crude solution a2 is a composition that contains bisphenol A and is liquid at 40°C or higher.

[0067] The content of bisphenol A in crude solution a2 (mass of bisphenol A / mass of crude solution a2×100(%)) is preferably less than 90% by mass. It is more preferably 85% by mass or less, and the lower the value, the more preferable it is in the order of 80% by mass or less, 70% by mass or less, and 60% by mass or less. If the content of bisphenol A is too high, the viscosity of crude solution a2 increases, making it difficult to transport.

[0068] The content of bisphenol A in the crude solution a2 is preferably 10% by mass or more, and the larger the value, the more preferable it is in the order of 20% by mass or more, 30% by mass or more, and 40% by mass or more. If the content of bisphenol A is too low, the amount of bisphenol A produced will be small, which is economically undesirable.

[0069] The crude solution a2 may contain a solvent other than bisphenol A. For example, when a solvent containing phenol is used, the crude solution a2 may contain phenol. The content of phenol contained in the crude solution a2 is preferably 10% by mass or more, more preferably 15% by mass or more, and particularly preferably 20% by mass or more. If the phenol content is too low, bisphenol A in the crude solution a2 may precipitate and form a slurry liquid, which may make it difficult to transport.

[0070] The water content of the crude solution a2 is usually adjusted to 0.01% by mass or less in order to efficiently decompose bisphenol A and the like into phenol and isopropenylphenol.

[0071] The crude solution a2 may contain heavy components such as incomplete decomposition products of polycarbonate resin (e.g., multimers such as bisphenol A dimers and trimers). However, if the amount of heavy components is too large, carbon dioxide may be generated in step (A3), causing pressure fluctuations and complicating reaction control. Therefore, the content of heavy components in the crude solution a2 is preferably 5% by mass or less, more preferably 1% by mass or less. The crude solution a2 may be thoroughly washed.

[0072] [Process (A3)] Step (A3) is a step of distilling the crude solution a2 obtained in step (A2) while or after decomposing bisphenol A contained therein, to recover a distillate a3 containing isopropenylphenol and phenol.

[0073] Bisphenol A is preferably decomposed into isopropenylphenol and phenol by alkaline decomposition under basic conditions. Examples of basic catalysts that can be used for the alkaline decomposition of bisphenol A include hydroxides, oxides, carbonates, and alkoxides of alkali metals such as sodium and potassium, and hydroxides, oxides, carbonates, and alkoxides of alkaline earth metals such as calcium and magnesium. Among these, sodium hydroxide or potassium hydroxide is preferred.

[0074] When a basic catalyst is used in step (A1) and is not distilled off in step (A2), the crude solution a2 is basic. In this case, the reaction may be carried out directly without adding a new basic catalyst in step (A3). In order to facilitate the decomposition of bisphenol A, it is preferable to add a new basic catalyst in step (A3).

[0075] The decomposition of bisphenol A is preferably carried out at a temperature higher than 150° C., more preferably 160° C. or higher, and even more preferably 170° C. or higher. The decomposition is preferably carried out at a temperature not higher than 250° C., and more preferably 240° C. or lower. If the temperature for decomposing bisphenol A is too low, the decomposition will be insufficient, which is undesirable, while if the temperature is too high, undesirable side reactions will occur, which will reduce the recovery rate of phenol and isopropenylphenol, which is undesirable.

[0076] The decomposition rate of bisphenol A in crude solution a2 is preferably 10 mol % or more, more preferably 20 mol % or more, and even more preferably 30 mol % or more. If the decomposition rate is too low, an increase in the amount of components that do not evaporate and remain as non-volatile liquids will occur. This component is undesirable as it becomes waste. The decomposition rate of bisphenol A in crude solution a2 can be calculated as the amount of isopropenylphenol contained in distillate a3 relative to the amount of bisphenol A in crude solution a2 (number of moles of isopropenylphenol / number of moles of bisphenol A in crude solution a2 × 100(%)).

[0077] The distillation can be carried out at a temperature higher than 150° C. The pressure is usually from 0.6 kPa to atmospheric pressure, preferably from 0.6 to 20 kPa, and more preferably from 0.8 to 10 kPa.

[0078] In step (A3), distillation can be performed while decomposing bisphenol A. For example, distillation can be performed while decomposing bisphenol A using a reactive distillation apparatus having a reaction vessel at the bottom and a distillation column at the top. Crude solution a2 and a basic catalyst are transferred to the reaction vessel at the bottom and heated, whereby the bisphenol A contained in crude solution a2 is decomposed into isopropenylphenol and phenol. At this time, incomplete decomposition products of polycarbonate resin (polymers such as bisphenol A dimers and trimers) and bisphenol A isomers (2,4-bis(4-hydroxyphenyl)propane) are also decomposed into isopropenylphenol and phenol. The phenol and isopropenylphenol produced by the decomposition are evaporated, extracted from the top of the reaction column, and recovered as fraction a3.

[0079] Furthermore, impurities such as chroman compounds undergo a heavier reaction, converting them into high-boiling substances (compounds with a boiling point higher than that of bisphenol A). The non-volatile liquid that remains in the reaction tank without evaporating contains concentrated high-boiling substances and substances (residues) that cause the coloring of bisphenol A. The residues are removed by withdrawing this non-volatile liquid from the bottom of the reaction tower.

[0080] In step (A3), distillation can be carried out after decomposing bisphenol A. For example, crude solution a2 is supplied to a reaction vessel to decompose bisphenol A. The resulting solution may then be transferred to a distillation column and distilled to recover isopropenylphenol and phenol.

[0081] Distillate a3 preferably contains 1.0% by mass or more of isopropenylphenol. If the content of isopropenylphenol in distillate a3 is less than 1.0% by mass, the amount of bisphenol A recovered after recombination will be small. Furthermore, distillate a3 preferably contains 59% by mass or less of isopropenylphenol, more preferably 45% by mass or less, and even more preferably 30% by mass or less. This is because if the content of isopropenylphenol is too high, it will turn into a condensate other than bisphenol A.

[0082] Furthermore, the distillate a3 preferably comprises isopropenylphenol and phenol, and the phenol content in the distillate a3 is preferably 99% by mass or less, more preferably 41% by mass or more, more preferably 55% by mass or more, and even more preferably 70% by mass or more.

[0083] The distillation is preferably carried out while extracting a portion of the non-volatile liquid from the system. By extracting the non-volatile liquid from the system, continuous operation becomes possible. The amount of the non-volatile liquid extracted from the system is appropriately adjusted depending on the amount of crude solution a2 used in step (A3).

[0084] Furthermore, the components in the extracted non-volatile liquid may be further decomposed using an acid catalyst. This decomposes those components that were not decomposed in step (A3), producing phenol. For example, the residue in the non-volatile liquid extracted from the system is decomposed at 150 to 300°C in the presence of an acid catalyst. The resulting phenol-containing solution is then distilled (at a temperature of 150 to 300°C and a pressure of 0.1 to 10 kPa) to recover phenol. This phenol can also be reused. Examples of acid catalysts used in this process include aromatic sulfonic acids such as p-toluenesulfonic acid. Furthermore, since the non-volatile liquid is basic, the amount of acid catalyst mixed in is controlled so that the residue can be decomposed under acidic conditions.

[0085] The obtained distillate a3 can be used to recombine isopropenylphenol and phenol in the distillate a3, thereby producing bisphenol A. By using the distillate a3 obtained by the method for producing an isopropenylphenol-containing solution of the present invention, bisphenol A having excellent optical properties can be obtained. The distillate a3 obtained by the method for producing an isopropenylphenol-containing solution of the present invention can be used in the method for producing a bisphenol A-containing solution of the present invention described below and the method for producing bisphenol A of the present invention.

[0086] <Method of manufacturing bisphenol A-containing solution> Fig. 2 is a flow chart showing an example of the method for producing a bisphenol A-containing solution of the present invention. The method for producing a bisphenol A-containing solution shown in Fig. 2 includes a step (A4) of contacting a distillate a3 obtained by the above-described method for producing an isopropenylphenol-containing solution of the present invention with an acid catalyst to recombine isopropenylphenol (IPP) and phenol (PHL) to produce bisphenol A (BPA), thereby obtaining a reaction solution a4 containing bisphenol A.

[0087] Examples of the acid catalyst used in step (A4) include inorganic acids such as sulfuric acid, hydrogen chloride, and phosphoric acid, organic acids such as p-toluenesulfonic acid, phenolsulfonic acid, and methanesulfonic acid, and acidic ion exchange resins. Among these, acidic ion exchange resins are preferred, and strongly acidic sulfonic acid cation exchange resins are more preferred.

[0088] The recombination can be carried out, for example, in a reactor filled with a sulfonic acid-type strongly acidic cation exchange resin. By supplying the solution (distillate a3) obtained by the method for producing an isopropenylphenol-containing solution of the present invention to this reactor, a recombination reaction between isopropenylphenol and phenol occurs, resulting in a reaction solution a4 containing bisphenol A. Alternatively, phenol may be supplied together with the distillate a3 so that a predetermined ratio of phenol to isopropenylphenol is achieved in the reactor where the recombination is carried out.

[0089] The reaction temperature for recombination is usually 45 to 130° C., preferably 50 to 100° C. The contact time with the acid catalyst is usually 5 to 200 minutes, preferably 15 to 120 minutes.

[0090] The resulting reaction liquid a4 contains bisphenol A (BPA) and phenol (PHL). The resulting reaction liquid a4 preferably contains bisphenol A in an amount of 50% by mass or less, more preferably 40% by mass or less. If the bisphenol A content is too high, the resulting bisphenol A will precipitate, which may easily clog the piping used to extract the reaction liquid a4 from the reactor where the recombination took place or to transfer it to the reactor where the next step will be performed. The content of bisphenol A in the reaction liquid a4 is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, and even more preferably 1.0% by mass or more. If the amount of bisphenol A is too small, there is a problem of reduced production efficiency.

[0091] <Bisphenol A manufacturing method> 3 to 8 are flow charts showing an example of the method for producing bisphenol A of the present invention. Hereinafter, the method for producing bisphenol A of the present invention will be described with reference to FIGS.

[0092] <Bisphenol A manufacturing method (1)> The method for producing bisphenol A of the present invention shown in FIG. 3 includes a step (A5) of purifying the reaction solution a4 obtained by the method for producing a bisphenol A-containing solution of the present invention to obtain bisphenol A (BPA).

[0093] The purification method is not particularly limited, and known methods can be used. For example, the method can include a step of crystallizing a reaction liquid a4 containing bisphenol A and phenol, followed by solid-liquid separation to obtain crystals of an adduct of bisphenol A and phenol, and a step of removing phenol from the crystals of the adduct of bisphenol A and phenol to obtain bisphenol A. The reaction liquid a4 may be used for crystallization after being appropriately washed or after being concentrated by distilling off the phenol. Phenol can be removed by a method of removing phenol from a molten liquid obtained by heating and melting crystals of an adduct of bisphenol A and phenol, or by a crystallization method using a hydrocarbon solvent such as toluene.

[0094] The method for producing bisphenol A of the present invention can also include a step of distilling off phenol from a reaction liquid a4 containing bisphenol A and phenol, and a step of crystallizing the crystals using a hydrocarbon solvent such as toluene, followed by solid-liquid separation to obtain bisphenol A.

[0095] <Bisphenol A manufacturing method (2)> 4 to 6 show a method for producing bisphenol A according to the present invention, in which the above-described bisphenol A-containing solution is incorporated into a process for producing bisphenol A from acetone and phenol, and the bisphenol A in the bisphenol A-containing solution is purified to produce bisphenol A. By incorporating the method into the process for producing bisphenol A from acetone and phenol in this way, bisphenol A with an excellent color tone that is sufficiently suitable for use as an optical material can be obtained at lower cost and with lower energy consumption.

[0096] The process for producing bisphenol A shown in Figure 4 is a step (B1) of dehydrating and condensing acetone and phenol in the presence of an acid catalyst to obtain a reaction liquid b1 containing bisphenol A; a step (B2) of distilling off unreacted acetone and water from the reaction liquid b1 obtained in the step (B1) to obtain a concentrated liquid b2; a step (B3) of crystallizing the concentrated liquid b2 obtained in the step (B2) to obtain a slurry liquid, and subjecting the slurry liquid to solid-liquid separation to separate it into a mother liquid b3 and a cake containing bisphenol A and phenol adduct crystals (BPA-PHL); Step (B4) of purifying the cake obtained in step (B3) to obtain bisphenol A (BPA); a step (B6A) of distilling the mother liquor b3 obtained in the step (B3) while or after decomposing bisphenol A contained therein to recover a distillate b6 containing isopropenylphenol (IPP) and phenol (PHL); a step (B7) of contacting the distillate b6 with an acid catalyst to recombine isopropenylphenol and phenol to produce bisphenol A, thereby obtaining a reaction solution b7 containing bisphenol A; and A part of the mother liquor b3 obtained in step (B3) is recycled and supplied to step (B1) and / or step (B2), A method for producing bisphenol A, comprising supplying the reaction liquid b7 obtained in step (B7) to step (B1) and / or step (B2), The reaction liquid a4 obtained by the above-described method for producing a bisphenol A-containing solution of the present invention is supplied to one or more steps selected from the group consisting of step (B1), step (B2), and step (B3).

[0097] Steps (B1) to (B7) will be explained below.

[0098] [Process (B1)] The step (B1) is a step in which acetone and phenol are subjected to dehydration condensation in the presence of an acid catalyst to obtain a reaction liquid b1 containing bisphenol A.

[0099] (acetone) The raw material acetone can be any commercially available one without any particular limitation. For example, acetone may be newly supplied from outside the system, or unreacted acetone distilled off in step (B2) described below may be recycled to be used as acetone in step (B1), or a mixture of these may be used.

[0100] (phenol) The raw material phenol can be any phenol available industrially without any particular limitation. For example, phenol may be newly supplied from outside the system, or unreacted phenol distilled off in step (B2) described later may be recycled to be used as phenol in step (B1), or a mixture of these may be used.

[0101] (acid catalyst) The acid catalyst is an acidic substance, and examples thereof include mineral acids such as hydrochloric acid and sulfuric acid, strongly acidic cation exchange resins, and solid acids such as polysiloxanes. Considering factors such as corrosion of the equipment, catalyst separation after the reaction, and catalytic activity, strongly acidic cation exchange resins, such as sulfonic acid-type resins, are typically used. Examples include styrene-divinylbenzene copolymer-type acidic cation exchange resins in which sulfonic acid groups have been introduced into approximately 2 to 16% of the total number of benzene rings. The average particle size is typically 0.2 to 2 mm, preferably 0.4 to 1.5 mm. To improve selectivity and conversion, it is preferable to add a sulfur-containing amine compound as a co-catalyst during the reaction or to support the acid catalyst. A suitable acid catalyst for step B is a strongly acidic cation exchange resin partially modified with a sulfur-containing amine compound.

[0102] (molar ratio of acetone to phenol) Although there is no particular limitation on the molar ratio of the raw materials phenol to acetone, it is preferable to use phenol in excess of the stoichiometric amount, i.e., 3 to 30 moles, preferably 5 to 20 moles, of phenol per mole of acetone. If the amount of phenol used per mole of acetone is less than 3 moles, the selectivity for bisphenol A decreases, and if it is more than 30 moles, problems such as a decrease in reaction rate and an increase in the size of the apparatus occur.

[0103] The condensation reaction of acetone and phenol can be carried out by a known method. The condensation reaction of phenol and acetone is not particularly limited to a reaction method, but is usually carried out by a fixed-bed flow method or a suspension-bed batch method. In the case of a fixed-bed flow method, the liquid hourly space velocity of the raw material mixture supplied to the reactor is usually 0.2 to 50 / hour. In the case of a suspension-bed batch method, the amount of acid catalyst used is usually 20 to 100 mass% of the raw material mixture, and the reaction time is usually 0.5 to 5 hours, although this varies depending on the reaction temperature and reaction pressure. Among these, a fixed-bed continuous reaction method is preferred, in which phenol and acetone are continuously supplied to a condensation reaction apparatus filled with an acidic cation exchange resin on which a co-catalyst is immobilized, and the reaction is carried out.

[0104] The reaction temperature is usually 40 to 130°C, preferably 40 to 90°C. A reaction temperature below 40°C is undesirable because the reaction liquid may solidify. Furthermore, at temperatures above 130°C, the acidic groups of the acidic cation exchange resin, which serves as the reaction catalyst, may be detached from the catalyst and contaminate bisphenol A, causing decomposition of bisphenol A, or the high temperature may cause decomposition of the catalyst, shortening its lifespan. The reaction pressure is usually normal pressure to 600 kPa (absolute pressure).

[0105] [Process (B2)] Step (B2) is a step of obtaining a concentrated liquid b2 by distilling off unreacted acetone and water from the reaction liquid b1 obtained in step (B1). The reaction liquid b1 obtained in step (B1) contains the produced bisphenol A, unreacted acetone, phenol, by-product water, bisphenol A isomers, etc. In step (B2), the reaction liquid b1 is distilled under reduced pressure or the like to remove light components including unreacted acetone and water from the reaction liquid b1, thereby obtaining a concentrated liquid b2 containing bisphenol A and phenol.

[0106] In step (B2), it is preferable to obtain a concentrated solution b2 by distilling off acetone, water, and a portion of phenol from the reaction solution b1 obtained in step (B1). By distilling off a portion of phenol, a concentrated solution b2 from which acetone and water have been thoroughly removed can be obtained.

[0107] For example, the reaction mixture b1 obtained in step (B1) can be transferred to a distillation column, and water, unreacted acetone, and a portion of the phenol are removed from the top of the column. The reaction product is then extracted from the bottom of the column to obtain a concentrate b2 to be used in step (B3). The concentrate b2 obtained is then subjected to step (B3). The distilled acetone may be recycled to step (B1). The distilled phenol may be recycled to step (B1) or used as a washing solvent for bisphenol A in step (B4).

[0108] The distillation is preferably carried out at a reaction temperature of 50 to 150°C and a pressure of 0.0065 to 0.040 MPa. It is generally preferable to remove acetone and water from the concentrated liquid b2 to a concentration of 0.1% by mass or less, respectively. This reduces the solubility of the adduct crystals during the crystallization procedure, improving the crystal yield. The concentration of bisphenol A in the concentrated liquid b2 is preferably 20 to 50% by mass. If the concentration of bisphenol A is less than 20% by mass, the yield will be low, and if it is greater than 50% by mass, the viscosity of the concentrated liquid b2 will increase, making transportation difficult.

[0109] [Process (B3)] Step (B3) is a step in which the concentrated liquid b2 obtained in step (B2) is crystallized to obtain a slurry liquid, and the slurry liquid is subjected to solid-liquid separation to separate it into a mother liquid b3 and a cake (solid content).

[0110] In step (B3), the concentrated liquid b2 is first crystallized to precipitate adduct crystals of bisphenol A and phenol. For example, the concentrated liquid b2 is adjusted to a temperature of typically 60 to 100°C, preferably 70 to 90°C, and then transferred to a crystallizer. The transferred concentrated liquid b2 is cooled in the crystallizer from 60 to 100°C (preferably 70 to 90°C) to 40 to 70°C, thereby precipitating the adduct crystals and forming a slurry. Next, the slurry in which the adduct crystals are dispersed is subjected to solid-liquid separation to separate the mother liquid b3 and a cake (solid content). The resulting mother liquid b3 contains unprecipitated bisphenol A and phenol. The cake is mainly composed of the adduct crystals.

[0111] Solid-liquid separation can be carried out by known means such as filtration or centrifugation, for example, using a horizontal belt filter, a rotary vacuum filter, a rotary pressure filter, a batch filter, a centrifugal filtration separator, a centrifugal sedimentation separator, or a hybrid type centrifugal separator thereof (screen ball decanter).

[0112] [Process (B4)] Step (B4) is a step of purifying the cake obtained in step (B3) to obtain bisphenol A. The method for purifying the cake is not particularly limited, and phenol can be separated from the cake obtained in step (B3) and bisphenol A can be recovered by methods such as removing phenol from a molten liquid obtained by heating and melting the cake, or crystallizing the phenol using a hydrocarbon solvent such as toluene.

[0113] A typical method for removing phenol from the cake involves heating and melting the cake to 100 to 160°C, and removing most of the phenol from the resulting molten liquid using, for example, a distillation apparatus, a thin-film evaporator, or a flash evaporator. Alternatively, to remove traces of phenol remaining in the molten liquid, the above-described procedure may be followed by steam stripping or the like to further remove the remaining phenol and purify bisphenol A. This method is described, for example, in JP-A-63-132850 and JP-A-2-28126.

[0114] The high-purity bisphenol A obtained in the molten state as described above is sent to a pelletizer or flaker and converted into solid prills or flakes to become the product bisphenol A. Alternatively, the obtained bisphenol A can be transferred to the next step in a molten state without being solidified, as in the case of supplying it to the production of polycarbonate resin by a melt process.

[0115] [Process (B6A)] Step (B6A) is a step of distilling the mother liquor b3 obtained in step (B3) while or after decomposing bisphenol A contained therein, to recover a distillate b6 containing isopropenylphenol and phenol. Step (B6A) can be carried out in the same manner as step (A3), except that mother liquor b3 is used instead of crude solution a2.

[0116] [Process (B7)] Step (B7) is a step in which the distillate b6 is brought into contact with an acid catalyst to recombine isopropenylphenol and phenol to produce bisphenol A, thereby obtaining a reaction liquid b7 containing bisphenol A. The reaction liquid b7 obtained in step (B7) is supplied to step (B1) and / or step (B2). Step (B7) can be carried out in the same manner as step (A4), except that distillate b6 is used instead of distillate a3.

[0117] [Supply of reaction solution a4] In the bisphenol A production method shown in FIG. 4, reaction liquid a4 is supplied to one or more steps selected from the group consisting of steps (B1), (B2), and (B3). Impurities such as coloring components derived from polycarbonate resins have been removed from the isopropenylphenol-containing solution. Reaction liquid a4, containing bisphenol A, obtained by recombining isopropenylphenol and phenol in this isopropenylphenol-containing solution also contains few impurities. Therefore, even if reaction liquid a4 is incorporated into an existing or new process for producing bisphenol A from acetone and phenol, it does not contaminate the individual steps, does not affect the quality of the produced bisphenol A, and can produce bisphenol A with excellent color tone. The method for supplying reaction liquid a4 is not particularly limited. It may be supplied directly to the equipment of each step, or, as shown in FIG. 5, it may be mixed with one or more solutions selected from the group consisting of reaction liquid b1, concentrated liquid b2, mother liquor b3, and reaction liquid b7 and then supplied to the equipment.

[0118] The amount of reaction liquid a4 supplied is not particularly limited. A larger supply amount is advantageous for the yield because the amount of bisphenol A produced by the decomposition of the polycarbonate resin increases. When supplying reaction liquid a4, it is desirable to operate the reaction liquid a4 so as not to cause precipitation of bisphenol A. Specifically, it is preferable to maintain the temperature of reaction liquid a4 at 50°C or higher and 120°C or lower.

[0119] The method for producing bisphenol A shown in Figure 6 is a step (B1) of dehydrating and condensing acetone and phenol in the presence of an acid catalyst to obtain a reaction liquid b1 containing bisphenol A; a step (B2) of distilling off unreacted acetone and water from the reaction liquid b1 obtained in the step (B1) to obtain a concentrated liquid b2; a step (B3) of crystallizing the concentrated liquid b2 obtained in the step (B2) to obtain a slurry liquid, and subjecting the slurry liquid to solid-liquid separation to separate it into a mother liquid b3 and a cake containing bisphenol A and phenol adduct crystals (BPA-PHL); Step (B4) of purifying the cake obtained in step (B3) to obtain bisphenol A (BPA); a step (B5) of isomerizing the mother liquor b3 obtained in the step (B3), followed by crystallization and solid-liquid separation to separate the mother liquor b5 and a cake containing bisphenol A; a step (B6B) of distilling the mother liquor b5 obtained in the step (B5) while or after decomposing bisphenol A contained therein to recover a distillate b6 containing isopropenylphenol (IPP) and phenol (PHL); a step (B7) of contacting the distillate b6 with an acid catalyst to recombine isopropenylphenol and phenol to produce bisphenol A, thereby obtaining a reaction solution b7 containing bisphenol A; and A part of the mother liquor b3 obtained in step (B3) is recycled and supplied to step (B1) and / or step (B2), A method for producing bisphenol A, comprising supplying the reaction liquid b7 obtained in step (B7) to step (B1) and / or step (B2), The reaction liquid a4 obtained by the above-described method for producing a bisphenol A-containing solution of the present invention is supplied to one or more steps selected from the group consisting of step (B1), step (B2), and step (B3).

[0120] The bisphenol A production methods shown in Figures 4 and 5 are methods in which the mother liquor b3 obtained after the solid-liquid separation in step (B3) is used as is in the step of decomposing bisphenol A into isopropenylphenol and phenol. In contrast, the bisphenol A production method shown in Figure 6 is a method in which the mother liquor b3 obtained after the solid-liquid separation in step (B3) is further isomerized, and then crystallized and solid-liquid separated to obtain a mother liquor b5, which is used to decompose bisphenol A into isopropenylphenol and phenol.

[0121] Steps (B1) to (B4) of the method for producing bisphenol A shown in FIG. 6 are the same as steps (B1) to (B4) of the method for producing bisphenol A shown in FIG.

[0122] [Process (B5)] The step (B5) is a step of isomerizing the mother liquor b3 obtained in the step (B3), followed by crystallization and solid-liquid separation to separate the mother liquor b5 and a cake containing bisphenol A.

[0123] (Isomerization treatment) The composition of the mother liquor b3 is typically 65 to 85 mass% phenol, 10 to 20 mass% bisphenol A (2,2-bis(4-hydroxyphenyl)propane), and 5 to 15 mass% 2,4-bis(4-hydroxyphenyl)propane, and contains a large amount of impurities such as an isomer of bisphenol A (2,4-bis(4-hydroxyphenyl)propane). The isomerization converts the isomer of bisphenol A to bisphenol A. The solution after the isomerization contains approximately 15 to 20 mass% bisphenol A and approximately 5 to 10 mass% 2,4-bis(4-hydroxyphenyl)propane. A portion of the solution after the isomerization is withdrawn and sent to a crystallizer to prevent the accumulation of impurities. A portion of the solution after the isomerization may be recycled to at least one of steps (B1), (B2), and (B3).

[0124] The isomerization treatment typically uses a sulfonic acid type cation exchange resin as a catalyst, and is carried out at a reaction temperature of about 50 to 100°C, with a liquid hourly space velocity (LHSV) of about 0.2 to 50 / hour in the case of a continuous fixed-bed flow method, which is a push-flow method.

[0125] (crystallization and solid-liquid separation) The solution after the isomerization treatment is cooled to crystallize bisphenol A and phenol adduct crystals (BPA-PHL) to obtain a slurry liquid. The solution after the isomerization treatment may be appropriately concentrated by distillation before use. The bisphenol A concentration in the concentrated liquid can be about 20 to 50 mass %. The concentration operation can be performed using a distillation column or the like, and is carried out at a pressure of about 5.3 to 40 kPa and a temperature of about 70 to 140°C. The evaporated phenol may also be reused as a washing liquid for washing the cake obtained after solid-liquid separation.

[0126] Next, the slurry liquid in which the adduct crystals of bisphenol A and phenol have been crystallized is subjected to solid-liquid separation to separate it into a mother liquor b5 and a cake of the adduct of bisphenol A and phenol. The solid-liquid separation can be carried out by a known method, similar to step (B3).

[0127] The cake of crystals of the adduct of bisphenol A and phenol is melted and then the phenol is removed from it alone or sent to step (B4) where the phenol is removed.

[0128] [Process (B6B)] Step (B6B) is a step of distilling the mother liquor b5 obtained in step (B5) while or after decomposing bisphenol A contained in the mother liquor b5, and recovering a distillate b6 containing isopropenylphenol and phenol. Step (B6B) can be carried out in the same manner as step (A3), except that mother liquor b5 is used instead of crude solution a2.

[0129] [Process (B7)] Step (B7) is a step in which the distillate b6 is brought into contact with an acid catalyst to recombine isopropenylphenol and phenol to produce bisphenol A, thereby obtaining a reaction solution b7 containing bisphenol A, and is the same as step (B7) in the method for producing bisphenol A in Figure 4.

[0130] [Supply of reaction solution a4] In the bisphenol A production method shown in Figure 6, reaction liquid a4 is supplied to one or more steps selected from the group consisting of step (B1), step (B2), and step (B3). As in the bisphenol A production method shown in Figure 4, the method for supplying reaction liquid a4 is not particularly limited, and it may be supplied directly to the apparatus of each step, or may be mixed with one or more solutions selected from the group consisting of reaction liquid b1, concentrated liquid b2, mother liquor b3, and reaction liquid b7 and then supplied to the apparatus. The supply amount and temperature of reaction liquid a4 are the same as in the bisphenol A production method shown in Figure 4.

[0131] <Bisphenol A manufacturing method (3)> The method for producing bisphenol A of the present invention shown in FIGS. 7 and 8 is a method for producing bisphenol A by incorporating the above-mentioned isopropenylphenol-containing solution into a process for producing bisphenol A from acetone and phenol.

[0132] The method for producing bisphenol A shown in Figure 7 is as follows: a step (B1) of dehydrating and condensing acetone and phenol in the presence of an acid catalyst to obtain a reaction liquid b1 containing bisphenol A; a step (B2) of distilling off unreacted acetone and water from the reaction liquid b1 obtained in the step (B1) to obtain a concentrated liquid b2; a step (B3) of crystallizing the concentrated liquid b2 obtained in the step (B2) to obtain a slurry liquid, and subjecting the slurry liquid to solid-liquid separation to separate it into a mother liquid b3 and a cake containing bisphenol A; a step (B4) of purifying the cake obtained in the step (B3) to obtain bisphenol A; a step (B6A) of distilling the mother liquor b3 obtained in the step (B3) while or after decomposing bisphenol A contained in the mother liquor b3, thereby recovering a distillate b6 containing isopropenylphenol and phenol; a step (B7) of contacting the distillate b6 with an acid catalyst to recombine isopropenylphenol and phenol to produce bisphenol A, thereby obtaining a reaction solution b7 containing bisphenol A; and A part of the mother liquor b3 obtained in step (B3) is recycled and supplied to step (B1) and / or step (B2), A method for producing bisphenol A, comprising supplying the reaction liquid b7 obtained in step (B7) to step (B1) and / or step (B2), The distillate a3 obtained in the above-mentioned method for producing an isopropenylphenol-containing solution is supplied to step (B7).

[0133] The method for producing bisphenol A shown in Figure 8 is as follows: a step (B1) of dehydrating and condensing acetone and phenol in the presence of an acid catalyst to obtain a reaction liquid b1 containing bisphenol A; a step (B2) of distilling off unreacted acetone and water from the reaction liquid b1 obtained in the step (B1) to obtain a concentrated liquid b2; a step (B3) of crystallizing the concentrated liquid b2 obtained in the step (B2) to obtain a slurry liquid, and subjecting the slurry liquid to solid-liquid separation to separate it into a mother liquid b3 and a cake containing bisphenol A; a step (B4) of purifying the cake obtained in the step (B3) to obtain bisphenol A; a step (B5) of isomerizing the mother liquor b3 obtained in the step (B3), followed by crystallization and solid-liquid separation to separate the mother liquor b5 and a cake containing bisphenol A; a step (B6B) of distilling the mother liquor b5 obtained in the step (B5) while or after decomposing bisphenol A contained in the mother liquor b5, thereby recovering a distillate b6 containing isopropenylphenol and phenol; a step (B7) of contacting the distillate b6 with an acid catalyst to recombine isopropenylphenol and phenol to produce bisphenol A, thereby obtaining a reaction solution b7 containing bisphenol A; and A part of the mother liquor b3 obtained in step (B3) is recycled and supplied to step (B1) and / or step (B2), A method for producing bisphenol A, comprising supplying the reaction liquid b7 obtained in step (B7) to step (B1) and / or step (B2), The above-mentioned isopropenylphenol-containing solution distillate a3 is supplied to step (B7).

[0134] Steps (B1) to (B7) of the method for producing bisphenol A shown in Fig. 7 are the same as steps (B1) to (B7) of the method for producing bisphenol A shown in Fig. 4. In addition, the method for producing bisphenol A shown in Fig. 8 is the same as steps (B1) to (B7) of the method for producing bisphenol A shown in Fig. 6.

[0135] [Supply of distillate a3] In the bisphenol A production method shown in Figures 7 and 8, distillate a3 is supplied to step (B7). Impurities such as coloring components derived from polycarbonate resins have been removed from the isopropenylphenol-containing solution. Therefore, even if distillate a3 is incorporated into a mother liquor circulation step of an existing or new process for producing bisphenol A from acetone and phenol, it will not contaminate the mother liquor, will not affect the quality of the produced bisphenol A, and bisphenol A with excellent color tone can be obtained. The method for supplying distillate a3 is not particularly limited; it may be supplied directly to an apparatus performing step (B7), or may be mixed with distillate b6 and supplied to the apparatus.

[0136] The amount of distillate a3 supplied to step (B7) is not particularly limited. The larger the amount supplied, the more bisphenol A can be obtained, which is advantageous for the yield.

[0137] <Uses of bisphenol A> Bisphenol A obtained by the method for producing bisphenol A of the present invention (hereinafter, sometimes referred to as "bisphenol A of the present invention") can be used as a constituent, curing agent, additive, or precursor thereof for various thermoplastic resins such as polyether resins, polyester resins, polyarylate resins, polycarbonate resins, polyurethane resins, and acrylic resins, and various thermosetting resins such as epoxy resins, unsaturated polyester resins, phenolic resins, polybenzoxazine resins, and cyanate resins, which are used in a variety of applications including optical materials, recording materials, insulating materials, transparent materials, electronic materials, adhesive materials, and heat-resistant materials. It is also useful as an additive for color developers and anti-fading agents for thermal recording materials, as well as for disinfectants, antibacterial and antifungal agents.

[0138] Among these, it is preferably used as a raw material (monomer) for thermoplastic resins and thermosetting resins, because it can impart good mechanical properties, and more preferably as a raw material for polycarbonate resins and epoxy resins. It is also preferably used as a color developer, and more preferably used in combination with a leuco dye or a discoloration temperature adjuster.

[0139] <Manufacturing method of polycarbonate resin> The present invention also relates to a method for producing a polycarbonate resin, in which bisphenol A is obtained through the method for producing bisphenol A of the present invention, and then a polycarbonate resin is produced using the bisphenol A (hereinafter, this may be referred to as the "method for producing a polycarbonate resin of the present invention").

[0140] The polycarbonate resin obtained by the method for producing a polycarbonate resin of the present invention can be produced by, for example, a method of subjecting the bisphenol A of the present invention to a transesterification reaction with a carbonate diester such as diphenyl carbonate in the presence of an alkali metal compound and / or an alkaline earth metal compound. As the raw material bisphenol A, the bisphenol A of the present invention may be used alone, or the bisphenol A of the present invention may be used in combination with bisphenol A obtained by a method other than the method for producing bisphenol A of the present invention.

[0141] The above transesterification reaction can be carried out by appropriately selecting a known method, but an example of the present invention using bisphenol A and diphenyl carbonate as raw materials will be described below.

[0142] In the above-mentioned method for producing a polycarbonate resin, it is preferable to use an excess amount of diphenyl carbonate relative to the bisphenol A of the present invention. A larger amount of diphenyl carbonate relative to the bisphenol A is preferable, since the produced polycarbonate resin will have fewer terminal hydroxyl groups and the polymer will have excellent thermal stability. A smaller amount is preferable, since the transesterification reaction rate is faster and it is easier to produce a polycarbonate resin with the desired molecular weight. For these reasons, the amount of diphenyl carbonate used relative to 1 mole of bisphenol A is usually 1.001 moles or more, preferably 1.002 moles or more, and usually 1.3 moles or less, preferably 1.2 moles or less.

[0143] As a method for supplying the raw materials, bisphenol A and diphenyl carbonate of the present invention can be supplied in a solid state, but it is preferable to melt one or both of them and supply them in a liquid state.

[0144] When producing a polycarbonate resin by the transesterification reaction of diphenyl carbonate and bisphenol A, a transesterification catalyst is usually used. In the above-mentioned method for producing a polycarbonate resin, it is preferable to use an alkali metal compound and / or an alkaline earth metal compound as the transesterification catalyst. These may be used alone or in any combination and ratio of two or more. In practice, it is desirable to use an alkali metal compound.

[0145] The amount of catalyst used per mole of bisphenol A or diphenyl carbonate is usually 0.05 μmol or more, preferably 0.08 μmol or more, more preferably 0.10 μmol or more, and usually 100 μmol or less, preferably 50 μmol or less, more preferably 20 μmol or less. When the amount of catalyst used is within the above range, it is easy to obtain the polymerization activity required to produce a polycarbonate resin having a desired molecular weight, and it is easy to obtain a polycarbonate resin that has excellent polymer color, does not undergo excessive polymer branching, and has excellent fluidity during molding.

[0146] To produce a polycarbonate resin by the above method, it is preferable to continuously feed both of the raw materials into a raw material mixing tank, and then continuously feed the resulting mixture and the transesterification catalyst into a polymerization tank.

[0147] In the production of polycarbonate resins by the transesterification method, the two raw materials are usually supplied to a raw material mixing tank, stirred uniformly, and then supplied to a polymerization tank to which a catalyst is added, thereby producing a polymer. [Example]

[0148] The present invention will be explained in more detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples as long as it does not depart from the gist of the invention.

[0149] [Raw materials and reagents] The polycarbonate resin used was "NOVAREX (registered trademark) M7027BF" manufactured by Mitsubishi Chemical Engineering Plastics Corporation. Phenol, sodium hydroxide, sulfuric acid, toluene, methanol, ethylene glycol, diethylamine, dimethyl carbonate, acetonitrile, and cesium carbonate were used as reagents from Fujifilm Wako Pure Chemical Industries, Ltd. The ion exchange resin used was Diaion (registered trademark) "SK104" manufactured by Mitsubishi Chemical Corporation. Diphenyl carbonate used was a product of Mitsubishi Chemical Corporation.

[0150] [Preparation of cation exchange resin] Cation exchange resin A: Diaion (registered trademark) SK104, which was completely substituted with phenol, was obtained according to Reference Example 1 described in Patent Document JP-A-2012-201619.

[0151] [analysis] Quantitative method: Internal standard method using biphenyl as an internal standard The confirmation of the production of bisphenol A, its purity, and the quantification of undecomposed polycarbonate resin and components thought to be stabilizers (components other than phenol and bisphenol A) were carried out by high performance liquid chromatography according to the following procedures and conditions. Equipment: Shimadzu LC-2010A, Waters 5μm 150mm x 4.6mm ID Method: Low-pressure gradient method ·Analysis temperature: 40℃ ·Eluent composition: Solution A: Acetonitrile Solution B: 85% phosphoric acid:water = 1 mL:999 mL solution At 0 min of analysis time, the eluent composition was A:B = 35:65 (volume ratio, same below), and from 0 to 5 min of analysis time, the eluent composition was A:B = 35:65, and then gradually changed to A:B = 90:10 from 5 to 40 min of analysis time. ·Flow rate: 0.85mL / min Detection wavelength: 280nm

[0152] [Viscosity average molecular weight (Mv)] The viscosity average molecular weight (Mv) was determined by dissolving the polycarbonate resin in methylene chloride (concentration: 6.0 g / L), measuring the specific viscosity (ηsp) at 20°C using an Ubbelohde viscometer, and calculating the viscosity average molecular weight (Mv) using the following formula. ηsp / C=[η](1+0.28ηsp) [η]=1.23×10 -4 Mv 0.83

[0153] [Pellet YI] Pellet YI (transparency of polycarbonate resin) was evaluated by measuring the YI value (yellowness index value) of reflected light of polycarbonate resin pellets in accordance with ASTM D 1925. The instrument used was a spectrophotometer "CM-5" manufactured by Konica Minolta, and the measurement conditions were a measurement diameter of 30 mm and SCE. The CM-A212 Petri dish calibration glass was fitted into the measurement unit, and the CM-A124 zero calibration box was placed over it to perform zero calibration. Then, the built-in white calibration plate was used to perform white calibration. Measurements were then performed using the CM-A210 white calibration plate, confirming that L* was 99.40±0.05, a* was 0.03±0.01, b* was -0.43±0.01, and YI was -0.58±0.01. YI was measured by filling a cylindrical glass container with an inner diameter of 30 mm and a height of 50 mm with pellets to a depth of about 40 mm. The pellets were removed from the glass container and the measurement was repeated twice, and the average of the three measurements was used.

[0154] [pH measurement] The pH was measured using a pH meter "pH METER ES-73" manufactured by Horiba Ltd., with respect to the aqueous phase at 25°C taken out of the flask.

[0155] [Example 1] <Process (A1)> Into a jacketed separable flask equipped with a Dimroth condenser, a stirring blade, and a thermometer, 72 g of water (72 g ÷ 18 g / mol = 4.0 mol, molar ratio of water to 1 mole of repeating unit of polycarbonate resin = 4.0 mol ÷ 0.4 mol = 10), 3 g of a 25 mass% aqueous sodium hydroxide solution, and 250 g of phenol were placed under a nitrogen atmosphere, and then 100 g of polycarbonate resin (since the molecular weight of the repeating unit of polycarbonate resin is 254 g / mol, the number of moles of repeating unit = 100 g ÷ 254 g / mol = 0.39 mol) was placed at room temperature. The jacket temperature was then raised to 110°C, causing reflux. The reaction was continued for 4 hours while maintaining the jacket temperature at 110°C, yielding a homogeneous reaction liquid (crude solution a1). The mass of the reaction liquid was 415g. The composition of a portion of the resulting reaction solution was confirmed by high performance liquid chromatography, and it was found to contain 21.3 mass% bisphenol A. The production rate of bisphenol A (BPA) based on the amount of BPA derived from the polycarbonate resin was 21.3 ÷ 100 × 415 g ÷ 228 g / mol ÷ 0.39 mol × 100 = 99 mol%.

[0156] <Process (A2)> The resulting reaction solution (crude solution a1) was transferred to a distillation apparatus equipped with a thermometer, a stirring blade, a distillation tube, a distillate receiver, and a pressure regulator. The pressure was adjusted from atmospheric pressure (101.33 kPa) to 16.00 kPa, and the internal temperature was raised from room temperature to 130°C while monitoring the distillate amount. Water and phenol were extracted, and 160 g of the bottoms (crude solution a2) were obtained.

[0157] <Process (A3)> Next, the pressure inside the distillation apparatus was set to 0.93 kPa, and the internal temperature was gradually increased to 210°C, thereby obtaining 124 g of a distillate (distillate a3) and 36 g of a non-volatile liquid in the distillation apparatus. The obtained non-volatile liquid was discarded. The composition of a portion of the distillate (distillate a3) obtained was confirmed by high-performance liquid chromatography, revealing that the content of isopropenylphenol was 18% by mass. The production rate of isopropenylphenol based on the BPA derived from the polycarbonate resin was 18 ÷ 100 × 124 g ÷ 134 g / mol ÷ 0.39 × 100 = 43 mol%.

[0158] <Process (A4)> A stirrer was placed in the receiver for the distillate (distillate a3), and the receiver was immersed in a water bath at 60°C. Then, 1 g of 1% by mass sulfuric acid was added, and the mixture was stirred for 30 minutes to obtain 125 g of a recombination reaction liquid (reaction liquid a4). The composition of a portion of the resulting recombination reaction liquid was confirmed by high-performance liquid chromatography, and it was found to contain 29% by mass of bisphenol A (recycled bisphenol A). The production rate of recycled bisphenol A, based on the BPA derived from the polycarbonate resin, was 29 ÷ 100 × 125 g ÷ 228 g / mol ÷ 0.39 × 100 = 40 mol%.

[0159] [Example 2] <Step (A1)> and <Step (A2)> were the same as in Example 1.

[0160] <Process (A3)> After adding 1 g of 25% by mass aqueous sodium hydroxide solution to the resulting bottoms (crude solution a2), the pressure inside the distillation apparatus was set to 0.93 kPa and the internal temperature was gradually raised to 210°C, yielding 127 g of distillate (distillate a3) in the distillate receiver and 33 g of non-volatile liquid in the distillation apparatus. The obtained non-volatile liquid was discarded. The composition of a portion of the distillate (distillate a3) obtained was confirmed by high-performance liquid chromatography, revealing that the content of isopropenylphenol was 21% by mass. The production rate of isopropenylphenol based on the BPA derived from the polycarbonate resin was 21 ÷ 100 × 127 g ÷ 134 g / mol ÷ 0.39 × 100 = 51 mol%.

[0161] <Process (A4)> A stirrer was placed in the receiver for the distillate (distillate a3F) and immersed in a water bath at 60°C. Then, 1 g of 1% by mass sulfuric acid was added and stirred for 30 minutes to obtain a recombination reaction liquid (reaction liquid a4). The composition of a portion of the obtained recombination reaction liquid (reaction liquid a4) was confirmed by high-performance liquid chromatography, and it was found to contain 33% by mass of bisphenol A (recycled bisphenol A). The production rate of recycled bisphenol A, based on the BPA derived from the polycarbonate resin, was 33 ÷ 100 × 128 g ÷ 228 g / mol ÷ 0.39 × 100 = 48 mol%.

[0162] [Comparative Example 1] A 200 mL autoclave equipped with an induction stirrer, a pressure gauge, and a thermometer was charged with 30 g of polycarbonate resin (30 g ÷ 254 g / mol = 0.12 mol), 100 g of phenol, and 1 g of sodium carbonate. After three nitrogen purges, the autoclave was placed in an electric furnace and reacted at an internal temperature of 250°C for 3 hours. After the reaction, the autoclave was immersed in ice water, and the internal pressure was returned to normal pressure to obtain a reaction liquid.

[0163] The resulting reaction liquid was placed in a distillation apparatus equipped with a thermometer, a stirring blade, a distillation tube, an oil bath and a pressure regulator.

[0164] Next, the temperature was gradually raised to 180°C, and while monitoring the amount of distillate, the internal pressure was gradually lowered from atmospheric pressure to 10 kPa to distill off 100 g of phenol, thereby obtaining a residue.

[0165] The distillation apparatus was evacuated to full vacuum. The oil bath temperature was then raised to 230°C, and 5 g of distillate was obtained. When the composition of a portion of the obtained distillate was confirmed by high-performance liquid chromatography, it was found to be mostly phenol, with no isopropenylphenol detected. Since regenerated bisphenol A cannot be obtained without obtaining isopropenylphenol, further reaction was abandoned.

[0166] Table 1 summarizes the production rates of bisphenol A after decomposing polycarbonate (PC) resin, the production rates of isopropenylphenol, and the production rates of bisphenol A by adding sulfuric acid for Examples 1 and 2 and Comparative Example 1. Table 1 shows that recycled bisphenol A can be obtained by first decomposing polycarbonate resin into bisphenol A, and then decomposing the bisphenol A to produce isopropenylphenol.

[0167] [Table 1]

[0168] [Reference example 1] A distillate from a bisphenol A production plant was obtained with reference to Example 1 described in Patent Document JP-A-2007-224020. The composition of the distillate (distillate b6) from the bisphenol A production plant was 92 mass % phenol, 2 mass % isopropenylphenol, and 6 mass % other components.

[0169] [Example 3] In the same manner as in Example 1, decomposition of the polycarbonate resin and decomposition of bisphenol A were carried out, and 124 g of a distillate (distillate a3) containing 18 mass % of isopropenylphenol was obtained.

[0170] (recombination) 1,000 g (isopropenylphenol content = 1,000 g × 2% by mass ÷ 100 = 20 g) of the distillate (distillate b6) from the bisphenol A production plant obtained in Reference Example 1 and 124 g (22 g of isopropenylphenol) of the distillate (distillate a3) were placed in a recovery flask equipped with a stirrer and mixed to obtain a mixed solution (amount of the mixed solution: 1,124 g, 22 g of isopropenylphenol + 20 g = 42 g, 42 g ÷ 134 g / mol = 0.3 mol). The recovery flask was then immersed in a 60°C water bath, and 1 g of 1% by mass sulfuric acid was added to the mixed solution. The mixture was stirred for 30 minutes to obtain a reaction solution. The composition of a portion of the resulting reaction liquid was confirmed by high performance liquid chromatography, and it was found that the content of bisphenol A (regenerated bisphenol A) was 5.5% by mass.

[0171] (neutralization) The resulting reaction solution was neutralized with a 25% by mass aqueous solution of sodium hydroxide to obtain a neutralized solution. The resulting neutralized solution was placed in a distillation apparatus equipped with a vacuum pump, a pressure reduction controller, a thermometer, a stirring blade, and a distillation tube. The pressure was adjusted from atmospheric pressure (101.33 kPa) to 16.00 kPa, and the internal temperature was raised from room temperature to 130°C while monitoring the distillation amount, thereby distilling off phenol and obtaining 155 g of bottoms containing bisphenol A.

[0172] (Crystallization / solid-liquid separation) The resulting bottoms were placed in a fully jacketed separable flask equipped with a thermometer and a stirring blade, after which 150 g of toluene and 100 g of demineralized water were added, and the internal temperature was raised to 80°C while mixing. The stirring was stopped and the mixture was allowed to stand, after which the lower aqueous phase was removed to obtain organic phase 1. The temperature of the obtained organic phase 1 was lowered from 80°C to 10°C to obtain slurry liquid 1. The obtained slurry liquid 1 was filtered using a vacuum filter to obtain 60 g of cake A.

[0173] The obtained cake A was placed in a fully jacketed separable flask equipped with a thermometer and a stirring blade, after which 300 g of toluene and 100 g of demineralized water were added, and the internal temperature was raised to 80°C while mixing. The stirring was stopped and the mixture was allowed to stand, after which the lower aqueous phase was removed to obtain organic phase 2. The obtained organic phase 2 was washed four times with 100 g of demineralized water to obtain organic phase 3. The temperature of organic phase 3 was lowered from 80°C to 10°C to obtain slurry liquid 2. The obtained slurry liquid 2 was filtered using a vacuum filter to obtain 50 g of cake B.

[0174] Cake B was dried using a rotary evaporator to obtain 45 g of bisphenol A. The melt color of the obtained bisphenol A was APHA15, and no undecomposed substances derived from the polycarbonate resin or components thought to be stabilizers were detected.

[0175] [Reference example 2] A recombination reaction liquid from a bisphenol A production plant was obtained with reference to Example 1 described in Patent Document JP-A-2007-224020. The composition of the recombined reaction liquid (reaction liquid b7) from the bisphenol A production plant was 91 mass % of phenol, 3 mass % of bisphenol A, and 6 mass % of other components.

[0176] [Example 4] 128 g of the recombination reaction liquid (reaction liquid a4) obtained in Example 1 was neutralized with a 25% by mass aqueous solution of sodium hydroxide to obtain a neutralized liquid.

[0177] The resulting neutralized liquid was mixed with 1000 g of the recombination reaction liquid from the bisphenol A production plant obtained in Reference Example 2, and the mixture was placed in a distillation apparatus equipped with a vacuum pump, a pressure reduction controller, a thermometer, a stirring blade, and a distillation tube.

[0178] The pressure was changed from normal pressure (101.33 kPa) to 16.00 kPa, and while monitoring the distillate amount, the internal temperature was increased from room temperature to 130°C to distill off phenol, yielding 155 g of bottoms containing bisphenol A.

[0179] The resulting bottoms were placed in a fully jacketed separable flask equipped with a thermometer and a stirring blade, and then 150 g of toluene and 100 g of demineralized water were added, and the internal temperature was raised to 80°C while mixing. Stirring was stopped and the mixture was allowed to stand, after which the lower aqueous phase was removed to obtain organic phase 1. The temperature of the obtained organic phase 1 was lowered from 80°C to 10°C to obtain slurry liquid 1. The obtained slurry liquid 1 was filtered using a vacuum filter to obtain 61 g of cake A.

[0180] The obtained cake A was placed in a fully jacketed separable flask equipped with a thermometer and a stirring blade, after which 300 g of toluene and 100 g of demineralized water were added, and the internal temperature was raised to 80°C while mixing. The stirring was stopped and the mixture was allowed to stand, after which the lower aqueous phase was removed to obtain organic phase 2. The obtained organic phase 2 was washed four times with 100 g of demineralized water to obtain organic phase 3. The temperature of organic phase 3 was lowered from 80°C to 10°C to obtain slurry liquid 2. The obtained slurry liquid 2 was filtered using a vacuum filter to obtain 53 g of cake B.

[0181] Cake B was dried using a rotary evaporator to obtain 44 g of bisphenol A. The melt color of the obtained bisphenol A was APHA18, and no undecomposed substances derived from the polycarbonate resin or components thought to be stabilizers were detected.

[0182] [Reference example 3] A bisphenol A reaction liquid (reaction liquid b1), a concentrated liquid (concentrated liquid b2), and a mother liquor (mother liquor b3) were obtained from a bisphenol A production plant by the method of Example 1 described in Patent Document JP-A-2007-224020. The composition of the bisphenol A reaction liquid (reaction liquid b1) from the bisphenol A production plant was 69 mass % phenol, 22 mass % bisphenol A, and 9 mass % other components. The composition of the concentrate (concentrate b2) from the bisphenol A production plant was 67 mass % phenol, 24 mass % bisphenol A, and 9 mass % other components. The composition of the mother liquor (mother liquor b3) from the bisphenol A production plant was 80 mass % phenol, 10 mass % bisphenol A, and 10 mass % other components.

[0183] [Example 5] 124 g of the recombination reaction liquid (reaction liquid a4) obtained in Example 1 was neutralized with a 25% by mass aqueous solution of sodium hydroxide to obtain a neutralized liquid.

[0184] The resulting neutralized liquid was mixed with 200 g of the bisphenol A mother liquor (mother liquor b3) from the bisphenol A production plant obtained in Reference Example 3, and the mixture was placed in a distillation apparatus equipped with a vacuum pump, a pressure reduction controller, a thermometer, a stirring blade, and a distillation tube. The pressure was adjusted from atmospheric pressure (101.33 kPa) to 16.00 kPa, and the internal temperature was raised from room temperature to 130°C while monitoring the distillate amount, thereby distilling off phenol, and 85 g of bottoms containing bisphenol A was obtained.

[0185] The resulting bottoms were placed in a fully jacketed separable flask equipped with a thermometer and a stirring blade, and then 200 g of toluene and 100 g of demineralized water were added, and the internal temperature was raised to 80°C while mixing. Stirring was stopped and the mixture was allowed to stand, after which the lower aqueous phase was removed to obtain organic phase 1. The temperature of the obtained organic phase 1 was lowered from 80°C to 10°C to obtain slurry liquid 1. The obtained slurry liquid 1 was filtered using a vacuum filter to obtain 59 g of cake A.

[0186] The obtained cake A was placed in a fully jacketed separable flask equipped with a thermometer and a stirring blade, after which 300 g of toluene and 100 g of demineralized water were added, and the internal temperature was raised to 80°C while mixing. The stirring was stopped and the mixture was allowed to stand, after which the lower aqueous phase was removed to obtain organic phase 2. The obtained organic phase 2 was washed four times with 100 g of demineralized water to obtain organic phase 3. The temperature of organic phase 3 was lowered from 80°C to 10°C to obtain slurry liquid 2. The obtained slurry liquid 2 was filtered using a vacuum filter to obtain 55 g of cake B.

[0187] Cake B was dried using a rotary evaporator to obtain 49 g of bisphenol A. The melt color of the obtained bisphenol A was APHA21, and no undecomposed substances derived from the polycarbonate resin or components thought to be stabilizers were detected.

[0188] [Example 6] 124 g of the recombination reaction liquid (reaction liquid a4) obtained in Example 1 was neutralized with a 25% by mass aqueous solution of sodium hydroxide to obtain a neutralized liquid.

[0189] The obtained neutralized liquid and 100 g of a concentrated liquid of bisphenol A (concentrated liquid b2) from a bisphenol A manufacturing plant were placed in a distillation apparatus equipped with a vacuum pump, a pressure reduction controller, a thermometer, a stirring blade, and a distillation tube.

[0190] The pressure was changed from normal pressure (101.33 kPa) to 16.00 kPa, and while monitoring the amount of distillate, the internal temperature was increased from room temperature to 130°C to distill off phenol, yielding 90 g of bottoms containing bisphenol A.

[0191] The resulting bottoms were placed in a fully jacketed separable flask equipped with a thermometer and a stirring blade, and then 210 g of toluene and 100 g of demineralized water were added, and the internal temperature was raised to 80°C while mixing. Stirring was stopped and the mixture was allowed to stand, after which the lower aqueous phase was removed to obtain organic phase 1. The temperature of the obtained organic phase 1 was lowered from 80°C to 10°C to obtain slurry liquid 1. The obtained slurry liquid 1 was filtered using a vacuum filter to obtain 68 g of cake A.

[0192] The obtained cake A was placed in a fully jacketed separable flask equipped with a thermometer and a stirring blade, after which 300 g of toluene and 100 g of demineralized water were added, and the internal temperature was raised to 80°C while mixing. The stirring was stopped and the mixture was allowed to stand, after which the lower aqueous phase was removed to obtain organic phase 2. The obtained organic phase 2 was washed four times with 100 g of demineralized water to obtain organic phase 3. The temperature of organic phase 3 was lowered from 80°C to 10°C to obtain slurry liquid 2. The obtained slurry liquid 2 was filtered using a vacuum filter to obtain 55 g of cake B.

[0193] Cake B was dried using a rotary evaporator to obtain 49 g of bisphenol A. The melt color of the obtained bisphenol A was APHA18, and no undecomposed substances derived from the polycarbonate resin or components thought to be stabilizers were detected.

[0194] [Example 7] 124 g of the recombination reaction liquid (reaction liquid a4) obtained in Example 1 was neutralized with a 25% by mass aqueous solution of sodium hydroxide to obtain a neutralized liquid.

[0195] The obtained neutralized liquid was mixed with 100 g of the reaction liquid of bisphenol A (reaction liquid b1) obtained in Reference Example 3 from the bisphenol A production plant, and the mixture was placed in a distillation apparatus equipped with a vacuum pump, a pressure reduction control device, a thermometer, a stirring blade, and a distillation tube.

[0196] The pressure was changed from normal pressure (101.33 kPa) to 16.00 kPa, and while monitoring the amount of distillate, the internal temperature was raised from room temperature to 130°C to distill off acetone, water, and phenol, yielding 90 g of bottoms containing bisphenol A.

[0197] The resulting bottoms were placed in a fully jacketed separable flask equipped with a thermometer and a stirring blade, and then 200 g of toluene and 100 g of demineralized water were added, and the internal temperature was raised to 80°C while mixing. Stirring was stopped and the mixture was allowed to stand, after which the lower aqueous phase was removed to obtain organic phase 1. The temperature of the obtained organic phase 1 was lowered from 80°C to 10°C to obtain slurry liquid 1. The obtained slurry liquid 1 was filtered using a vacuum filter to obtain 66 g of cake A.

[0198] The obtained cake A was placed in a fully jacketed separable flask equipped with a thermometer and a stirring blade, after which 300 g of toluene and 100 g of demineralized water were added, and the internal temperature was raised to 80°C while mixing. The stirring was stopped and the mixture was allowed to stand, after which the lower aqueous phase was removed to obtain organic phase 2. The obtained organic phase 2 was washed four times with 100 g of demineralized water to obtain organic phase 3. The temperature of organic phase 3 was lowered from 80°C to 10°C to obtain slurry liquid 2. The obtained slurry liquid 2 was filtered using a vacuum filter to obtain 58 g of cake B.

[0199] Cake B was dried using a rotary evaporator to obtain 53 g of bisphenol A. The melt color of the obtained bisphenol A was APHA21, and no undecomposed substances derived from the polycarbonate resin or components thought to be stabilizers were detected.

[0200] [Example 8] <Process (A1)> A jacketed separable flask equipped with a Dimroth condenser, a stirring blade, and a thermometer was charged with 29 g of methanol (29 g ÷ 32 g / mol = 0.9 mol), 300 g of phenol, and 10 g of 25% by mass aqueous sodium hydroxide solution under a nitrogen atmosphere, followed by 100 g of polycarbonate resin (the molecular weight of the repeating unit of the polycarbonate resin is 254 g / mol, so the number of moles of the repeating unit = 100 g ÷ 254 g / mol = 0.4 mol) at room temperature. The mass of the reaction solution was 439 g. Thereafter, the jacket temperature was raised to 85° C., causing reflux. The reaction was continued for 4 hours while maintaining the jacket temperature at 85° C., to obtain a homogeneous reaction solution. The composition of a portion of the resulting reaction solution was confirmed by high performance liquid chromatography, and it was found to contain 20 mass% bisphenol A. The production rate of bisphenol A (BPA) based on the amount of BPA derived from the polycarbonate resin was 20 ÷ 100 × 439 g ÷ 228 g / mol ÷ 0.4 mol × 100 = 96 mol%.

[0201] <Process (A2)> The resulting reaction mixture was transferred to a distillation apparatus equipped with a thermometer, a stirring blade, a distillation tube, a distillate receiver, and a pressure regulator. The pressure was adjusted from atmospheric pressure (101.33 kPa) to 16.00 kPa, and the internal temperature was raised from room temperature to 130°C while monitoring the distillate amount. Methanol, dimethyl carbonate, and phenol were extracted, yielding 172 g of bottom residue.

[0202] <Process (A3)> Next, the pressure inside the distillation apparatus was set to 0.93 kPa, and the internal temperature was gradually raised to 210°C, thereby obtaining 119 g of distillate in the distillate receiver and 53 g of non-volatile liquid in the distillation apparatus. The obtained non-volatile liquid was discarded. The composition of a portion of the distillate was confirmed by high-performance liquid chromatography, revealing that the isopropenylphenol content was 16% by mass. The production rate of isopropenylphenol based on the BPA derived from the polycarbonate resin was 16 ÷ 100 × 119 g ÷ 134 g / mol ÷ 0.4 × 100 = 36 mol%.

[0203] <Process (A4)> A stirrer was placed in the receiver for the distillate, and the receiver was immersed in a water bath at 60°C. Then, 1 g of 1% by mass sulfuric acid was added, and the mixture was stirred for 30 minutes to obtain a recombination reaction solution. The composition of a portion of the obtained recombination reaction solution was confirmed by high-performance liquid chromatography, and it was found to contain 26% by mass of bisphenol A (regenerated bisphenol A). The production rate of recycled bisphenol A, based on the BPA derived from the polycarbonate resin, was 26 ÷ 100 × 119 g ÷ 228 g / mol ÷ 0.4 × 100 = 34 mol%.

[0204] 119 g of the resulting recombination reaction liquid was neutralized with a 25% by mass aqueous solution of sodium hydroxide to obtain a neutralized liquid.

[0205] The resulting neutralized solution and 100 g of the concentrated solution of bisphenol A from a bisphenol A production plant obtained in Reference Example 3 were placed in a distillation apparatus equipped with a vacuum pump, a pressure reduction controller, a thermometer, a stirring blade, and a distillation tube. The pressure was adjusted from atmospheric pressure (101.33 kPa) to 16.00 kPa, and the internal temperature was raised from room temperature to 130°C while monitoring the distillate amount, thereby distilling off phenol and obtaining 91 g of bottoms containing bisphenol A.

[0206] The resulting bottoms were placed in a fully jacketed separable flask equipped with a thermometer and a stirring blade, and then 200 g of toluene and 100 g of demineralized water were added, and the internal temperature was raised to 80°C while mixing. The stirring was stopped and the mixture was allowed to stand, after which the lower aqueous phase was removed to obtain organic phase 1. The temperature of the obtained organic phase 1 was lowered from 80°C to 10°C to obtain slurry liquid 1. The obtained slurry liquid 1 was filtered using a vacuum filter to obtain 65 g of cake A.

[0207] The obtained cake A was placed in a fully jacketed separable flask equipped with a thermometer and a stirring blade, after which 300 g of toluene and 100 g of demineralized water were added, and the internal temperature was raised to 80°C while mixing. The stirring was stopped and the mixture was allowed to stand, after which the lower aqueous phase was removed to obtain organic phase 2. The obtained organic phase 2 was washed four times with 100 g of demineralized water to obtain organic phase 3. The temperature of organic phase 3 was lowered from 80°C to 10°C to obtain slurry liquid 2. The obtained slurry liquid 2 was filtered using a vacuum filter to obtain 55 g of cake B.

[0208] Cake B was dried using a rotary evaporator to obtain 48 g of bisphenol A. The melt color of the obtained bisphenol A was APHA22, and no undecomposed substances derived from the polycarbonate resin or components thought to be stabilizers were detected.

[0209] [Example 9] <Process (A1)> A jacketed separable flask equipped with a Dimroth condenser, a stirring blade, and a thermometer was charged with 24 g of ethylene glycol (24 g ÷ 62 g / mol = 0.4 mol), 300 g of phenol, and 10 g of a 25% by mass aqueous solution of sodium hydroxide under a nitrogen atmosphere, followed by 100 g of polycarbonate resin (the molecular weight of the repeating unit of the polycarbonate resin is 254 g / mol, so the number of moles of the repeating unit = 100 g ÷ 254 g / mol = 0.4 mol) at room temperature. The total mass of the reaction solution was 434 g. Thereafter, the jacket temperature was raised to 85° C., causing reflux. The reaction was continued for 4 hours while maintaining the jacket temperature at 85° C., to obtain a homogeneous reaction solution. The composition of a portion of the resulting reaction solution was confirmed by high performance liquid chromatography, and it was found to contain 20 mass% bisphenol A. The production rate of bisphenol A (BPA) based on the amount of BPA derived from the polycarbonate resin was 20 ÷ 100 × 434 g ÷ 228 g / mol ÷ 0.4 mol × 100 = 95 mol%.

[0210] <Process (A2)> The resulting reaction mixture was transferred to a distillation apparatus equipped with a thermometer, a stirring blade, a distillation tube, a distillate receiver, and a pressure regulator. The pressure was adjusted from atmospheric pressure (101.33 kPa) to 16.00 kPa, and the internal temperature was raised from room temperature to 130°C while monitoring the distillate amount. Ethylene carbonate and phenol were extracted, and 190 g of bottoms were obtained.

[0211] <Process (A3)> Next, the pressure inside the distillation apparatus was set to 0.93 kPa, and the internal temperature was gradually raised to 210°C, thereby obtaining 108 g of distillate in the distillate receiver and 82 g of non-volatile liquid in the distillation apparatus. The obtained non-volatile liquid was discarded. The composition of a portion of the distillate was confirmed by high-performance liquid chromatography, revealing that the isopropenylphenol content was 13% by mass. The production rate of isopropenylphenol based on the BPA derived from the polycarbonate resin was 13 ÷ 100 × 108 g ÷ 134 g / mol ÷ 0.4 × 100 = 26 mol%.

[0212] <Process (A4)> A stirrer was placed in the receiver for the distillate, and the receiver was immersed in a water bath at 60°C. Then, 1 g of 1% by mass sulfuric acid was added, and the mixture was stirred for 30 minutes to obtain 109 g of a recombination reaction liquid. The composition of a portion of the obtained recombination reaction liquid was confirmed by high-performance liquid chromatography, and it was found to contain 21% by mass of bisphenol A (regenerated bisphenol A). The production rate of recycled bisphenol A, based on the BPA derived from the polycarbonate resin, was 21 ÷ 100 × 109 g ÷ 228 g / mol ÷ 0.4 × 100 = 25 mol%.

[0213] 109 g of the resulting recombination reaction liquid was neutralized with a 25% by mass aqueous solution of sodium hydroxide to obtain a neutralized liquid.

[0214] The resulting neutralized solution and 100 g of the concentrated solution of bisphenol A from a bisphenol A production plant obtained in Reference Example 3 were placed in a distillation apparatus equipped with a vacuum pump, a pressure reduction controller, a thermometer, a stirring blade, and a distillation tube. The pressure was adjusted from atmospheric pressure (101.33 kPa) to 16.00 kPa, and the internal temperature was raised from room temperature to 130°C while monitoring the distillation amount, thereby distilling off phenol and obtaining 85 g of bottoms containing bisphenol A.

[0215] The resulting bottoms were placed in a fully jacketed separable flask equipped with a thermometer and a stirring blade, and then 200 g of toluene and 100 g of demineralized water were added, and the internal temperature was raised to 80°C while mixing. Stirring was stopped and the mixture was allowed to stand, after which the lower aqueous phase was removed to obtain organic phase 1. The temperature of the obtained organic phase 1 was lowered from 80°C to 10°C to obtain slurry liquid 1. The obtained slurry liquid 1 was filtered using a vacuum filter to obtain 45 g of cake A.

[0216] The obtained cake A was placed in a fully jacketed separable flask equipped with a thermometer and a stirring blade, after which 300 g of toluene and 100 g of demineralized water were added, and the internal temperature was raised to 80°C while mixing. The stirring was stopped and the mixture was allowed to stand, after which the lower aqueous phase was removed to obtain organic phase 2. The obtained organic phase 2 was washed four times with 100 g of demineralized water to obtain organic phase 3. The temperature of organic phase 3 was lowered from 80°C to 10°C to obtain slurry liquid 2. The obtained slurry liquid 2 was filtered using a vacuum filter to obtain 42 g of cake B.

[0217] Cake B was dried using a rotary evaporator to obtain 39 g of bisphenol A. The melt color of the obtained bisphenol A was APHA18, and no undecomposed substances derived from the polycarbonate resin or components thought to be stabilizers were detected.

[0218] [Example 10] <Process (A1)> Diethylamine (57 g ÷ 73 g / mol = 0.8 mol) and 500 g of phenol were placed in a jacketed separable flask equipped with a Dimroth condenser, a stirring blade, and a thermometer under a nitrogen atmosphere, followed by 100 g of polycarbonate resin (since the molecular weight of the repeating unit of the polycarbonate resin is 254 g / mol, the number of moles of the repeating unit = 100 g ÷ 254 g / mol = 0.4 mol) at room temperature. The mass of the reaction liquid was 657 g. Thereafter, the jacket temperature was raised to 85° C., causing reflux. The reaction was continued for 4 hours while maintaining the jacket temperature at 85° C., to obtain a homogeneous reaction solution. The composition of a portion of the resulting reaction solution was confirmed by high performance liquid chromatography, and it was found to contain 13 mass% bisphenol A. The production rate of bisphenol A (BPA) based on the amount of BPA derived from the polycarbonate resin was 13 ÷ 100 × 657 g ÷ 228 g / mol ÷ 0.4 mol × 100 = 94 mol%.

[0219] <Process (A2)> The resulting reaction mixture was transferred to a distillation apparatus equipped with a thermometer, a stirring blade, a distillation tube, a distillate receiver, and a pressure regulator. The pressure was adjusted from atmospheric pressure (101.33 kPa) to 16.00 kPa, and the internal temperature was raised from room temperature to 130°C while monitoring the distillate amount. Tetraethylurea and phenol were extracted, and 150 g of bottom residue was obtained.

[0220] <Process (A3)> The pressure was then returned to normal pressure (101.33 kPa), and 4 g of a 25% by mass aqueous solution of sodium hydroxide was added. The pressure inside the distillation apparatus was then returned to 0.93 kPa, and the internal temperature was gradually increased to 210°C, yielding 80 g of distillate in the distillate receiver and 70 g of non-volatile liquid in the distillation apparatus. The obtained non-volatile liquid was discarded. The composition of a portion of the distillate was confirmed by high-performance liquid chromatography, revealing that the isopropenylphenol content was 9% by mass. The production rate of isopropenylphenol based on the BPA derived from the polycarbonate resin was 9 / 100×80g / 134g / mol / 0.4×100=13% by mole.

[0221] <Process (A4)> A stirrer was placed in the receiver for the distillate, and the receiver was immersed in a water bath at 60°C. Then, 1 g of 1% by mass sulfuric acid was added, and the mixture was stirred for 30 minutes to obtain 229 g of a recombination reaction liquid. The composition of a portion of the obtained recombination reaction liquid was confirmed by high-performance liquid chromatography, and it was found to contain 14% by mass of bisphenol A (regenerated bisphenol A). The production rate of recycled bisphenol A, based on the BPA derived from the polycarbonate resin, was 14 ÷ 100 × 80 g ÷ 229 g / mol ÷ 0.4 × 100 = 12 mol%.

[0222] 80 g of the resulting recombination reaction liquid was neutralized with a 25% by mass aqueous solution of sodium hydroxide to obtain a neutralized liquid.

[0223] The resulting neutralized solution and 100 g of the concentrated solution of bisphenol A from a bisphenol A production plant obtained in Reference Example 3 were placed in a distillation apparatus equipped with a vacuum pump, a pressure reduction controller, a thermometer, a stirring blade, and a distillation tube. The pressure was adjusted from atmospheric pressure (101.33 kPa) to 16.00 kPa, and the internal temperature was raised from room temperature to 130°C while monitoring the distillation amount, thereby distilling off phenol and obtaining 65 g of bottoms containing bisphenol A.

[0224] The resulting bottoms were placed in a fully jacketed separable flask equipped with a thermometer and a stirring blade, after which 150 g of toluene and 100 g of demineralized water were added and the internal temperature was raised to 80°C while mixing. Stirring was stopped and the mixture was allowed to stand, after which the lower aqueous phase was removed to obtain organic phase 1. The temperature of the obtained organic phase 1 was lowered from 80°C to 10°C to obtain slurry liquid 1. The obtained slurry liquid 1 was filtered using a vacuum filter to obtain 35 g of cake A.

[0225] The obtained cake A was placed in a fully jacketed separable flask equipped with a thermometer and a stirring blade, after which 210 g of toluene and 100 g of demineralized water were added, and the internal temperature was raised to 80°C while mixing. The stirring was stopped and the mixture was allowed to stand, after which the lower aqueous phase was removed to obtain organic phase 2. The obtained organic phase 2 was washed four times with 100 g of demineralized water to obtain organic phase 3. The temperature of organic phase 3 was lowered from 80°C to 10°C to obtain slurry liquid 2. The obtained slurry liquid 2 was filtered using a vacuum filter to obtain 31 g of cake B.

[0226] Cake B was dried using a rotary evaporator to obtain 26 g of bisphenol A. The melt color of the obtained bisphenol A was APHA18, and no undecomposed substances derived from the polycarbonate resin or components thought to be stabilizers were detected.

[0227] [Example 11] <Process (A1)> In a jacketed separable flask equipped with a Dimroth condenser, a stirring blade, and a thermometer, 65 g of methanol (65 g ÷ 32 g / mol = 2 mols, molar ratio of methanol to 1 mole of polycarbonate resin repeating unit = 2 mol ÷ 0.4 mol = 5), 150 g of dimethyl carbonate, and 1 g of potassium hydroxide were placed under a nitrogen atmosphere, followed by 100 g of polycarbonate resin (since the molecular weight of the polycarbonate resin repeating unit is 254 g / mol, the number of moles of repeating unit = 100 g ÷ 254 g / mol = 0.4 mol) at room temperature. The mass of the reaction liquid was 316 g. The jacket temperature was then raised to 70°C. Undissolved polycarbonate resin was observed in the reaction solution when it reached 70°C (it was in a slurry state). The reaction was continued for 5 hours while maintaining the jacket temperature at 65°C, and a homogeneous reaction solution was obtained. The composition of a portion of the resulting reaction solution was confirmed by high performance liquid chromatography, and it was found to be 27% by mass of bisphenol A. The production rate of bisphenol A (BPA) based on the BPA derived from the polycarbonate resin was 27 ÷ 100 × 316 g ÷ 228 g / mol ÷ 0.4 mol × 100 = 94 mol%.

[0228] <Process (A2)> The resulting reaction liquid was transferred to a distillation apparatus equipped with a thermometer, a stirring blade, a distillation tube, a distillate receiver, and a pressure regulator. The pressure was set to normal pressure (101.33 kPa) and the internal temperature was set to 100°C, and a portion of the methanol and dimethyl carbonate was distilled off. Thereafter, 180 g of phenol was added, and the pressure was changed from normal pressure (101.33 kPa) to 16.00 kPa. While monitoring the amount of distillation, the internal temperature was raised to 130°C, and the dimethyl carbonate and phenol were removed, yielding 225 g of bottom residue.

[0229] <Process (A3)> Next, the pressure inside the distillation apparatus was set to 0.93 kPa, and the internal temperature was gradually raised to 210°C, thereby obtaining 153 g of distillate in the distillate receiver and 72 g of non-volatile liquid in the distillation apparatus. The obtained non-volatile liquid was discarded. The composition of a portion of the distillate was confirmed by high-performance liquid chromatography, revealing that the isopropenylphenol content was 17% by mass. The production rate of isopropenylphenol based on the BPA derived from the polycarbonate resin was 17 ÷ 100 × 153 g ÷ 134 g / mol ÷ 0.4 × 100 = 49 mol%.

[0230] <Process (A4)> A stirrer was placed in the receiver for the distillate, and the receiver was immersed in a water bath at 60°C. Then, 1 g of 1% by mass sulfuric acid was added, and the mixture was stirred for 30 minutes to obtain 154 g of a recombination reaction liquid. The composition of a portion of the obtained recombination reaction liquid was confirmed by high-performance liquid chromatography, and it was found to contain 27% by mass of bisphenol A (regenerated bisphenol A). The production rate of recycled bisphenol A, based on bisphenol A (BPA) derived from polycarbonate resin, was 27 ÷ 100 × 154 g ÷ 228 g / mol ÷ 0.4 × 100 = 25 mol%.

[0231] 154 g of the resulting recombination reaction liquid was neutralized with a 25% by mass aqueous solution of sodium hydroxide to obtain a neutralized liquid.

[0232] The resulting neutralized solution was mixed with 100 g of the concentrated solution of bisphenol A from the bisphenol A production plant obtained in Reference Example 3, and the mixture was placed in a distillation apparatus equipped with a vacuum pump, a pressure reduction controller, a thermometer, a stirring blade, and a distillation tube. The pressure was adjusted from atmospheric pressure (101.33 kPa) to 16.00 kPa, and the internal temperature was raised from room temperature to 130°C while monitoring the distillation amount, thereby distilling off phenol and obtaining 157 g of bottom residue containing bisphenol A.

[0233] The resulting bottoms were placed in a fully jacketed separable flask equipped with a thermometer and a stirring blade, after which 350 g of toluene and 100 g of demineralized water were added, and the internal temperature was raised to 80°C while mixing. Stirring was stopped and the mixture was allowed to stand, after which the lower aqueous phase was removed to obtain organic phase 1. The temperature of the obtained organic phase 1 was lowered from 80°C to 10°C to obtain slurry liquid 1. The obtained slurry liquid 1 was filtered using a vacuum filter to obtain 55 g of cake A.

[0234] The obtained cake A was placed in a fully jacketed separable flask equipped with a thermometer and a stirring blade, after which 300 g of toluene and 100 g of demineralized water were added, and the internal temperature was raised to 80°C while mixing. The stirring was stopped and the mixture was allowed to stand, after which the lower aqueous phase was removed to obtain organic phase 2. The obtained organic phase 2 was washed four times with 100 g of demineralized water to obtain organic phase 3. The temperature of organic phase 3 was lowered from 80°C to 10°C to obtain slurry liquid 2. The obtained slurry liquid 2 was filtered using a vacuum filter to obtain 52 g of cake B.

[0235] Cake B was dried using a rotary evaporator to obtain 48 g of bisphenol A. The melt color of the obtained bisphenol A was APHA9, and no undecomposed substances derived from the polycarbonate resin or components thought to be stabilizers were detected.

[0236] [Example 12] <Process (A5)> 124 g of the recombination reaction liquid obtained in Example 1 was neutralized with a 25% by mass aqueous solution of sodium hydroxide to obtain a neutralized liquid.

[0237] The resulting neutralized solution was placed in a distillation apparatus equipped with a vacuum pump, a pressure reduction controller, a thermometer, a stirring blade, and a distillation tube. The pressure was adjusted from atmospheric pressure (101.33 kPa) to 16.00 kPa, and the internal temperature was raised from room temperature to 130°C while monitoring the distillation amount, thereby distilling off phenol and obtaining 75 g of bottoms containing bisphenol A.

[0238] The resulting bottoms were placed in a fully jacketed separable flask equipped with a thermometer and a stirring blade, and then 100 g of toluene and 100 g of demineralized water were added and the internal temperature was raised to 80°C while mixing. Stirring was stopped and the mixture was allowed to stand, after which the lower aqueous phase was removed to obtain organic phase 1. The temperature of the obtained organic phase 1 was lowered from 80°C to 10°C to obtain slurry liquid 1. The obtained slurry liquid 1 was filtered using a vacuum filter to obtain 36 g of cake A.

[0239] The obtained cake A was placed in a fully jacketed separable flask equipped with a thermometer and a stirring blade, after which 250 g of toluene and 100 g of demineralized water were added, and the internal temperature was raised to 80°C while mixing. The stirring was stopped and the mixture was allowed to stand, after which the lower aqueous phase was removed to obtain organic phase 2. The obtained organic phase 2 was washed four times with 100 g of demineralized water to obtain organic phase 3. The temperature of organic phase 3 was lowered from 80°C to 10°C to obtain slurry liquid 2. The obtained slurry liquid 2 was filtered using a vacuum filter to obtain 34 g of cake B.

[0240] Cake B was dried using a rotary evaporator to obtain 26 g of bisphenol A. The melt color of the obtained bisphenol A was APHA23, and no undecomposed substances derived from the polycarbonate resin or components thought to be stabilizers were detected.

[0241] [Example 13] <Process (A5)> 125 g of the distillate (distillate a3) obtained in step (A3) of Example 1 was placed in a recovery flask equipped with a stirrer, and then 3 g of Diaion SK104 substituted with phenol was added. The recovery flask was immersed in a water bath at 60°C and stirred for 1 hour, after which the mixture was filtered using filter paper to obtain a filtrate.

[0242] The obtained filtrate was placed in a distillation apparatus equipped with a vacuum pump, a pressure reduction controller, a thermometer, a stirring blade, and a distillation tube. The pressure was adjusted from atmospheric pressure (101.33 kPa) to 16.00 kPa, and the internal temperature was raised from room temperature to 130°C while monitoring the distillation amount, thereby distilling off phenol and obtaining 72 g of bottoms containing bisphenol A.

[0243] The resulting bottoms were placed in a fully jacketed separable flask equipped with a thermometer and a stirring blade, and then 100 g of toluene and 100 g of demineralized water were added and the internal temperature was raised to 80°C while mixing. Stirring was stopped and the mixture was allowed to stand, after which the lower aqueous phase was removed to obtain organic phase 1. The temperature of the obtained organic phase 1 was lowered from 80°C to 10°C to obtain slurry liquid 1. The obtained slurry liquid 1 was filtered using a vacuum filter to obtain 35 g of cake A.

[0244] The obtained cake A was placed in a fully jacketed separable flask equipped with a thermometer and a stirring blade, after which 250 g of toluene and 100 g of demineralized water were added, and the internal temperature was raised to 80°C while mixing. The stirring was stopped and the mixture was allowed to stand, after which the lower aqueous phase was removed to obtain organic phase 2. The obtained organic phase 2 was washed four times with 100 g of demineralized water to obtain organic phase 3. The temperature of organic phase 3 was lowered from 80°C to 10°C to obtain slurry liquid 2. The obtained slurry liquid 2 was filtered using a vacuum filter to obtain 31 g of cake B.

[0245] Cake B was dried using a rotary evaporator to obtain 24 g of bisphenol A. The melt color of the obtained bisphenol A was APHA19, and no undecomposed substances derived from the polycarbonate resin or components thought to be stabilizers were detected.

[0246] <Comparative Example 2> 160 g of the bottoms from Example 1 and 200 g of the concentrate from the bisphenol A production plant obtained in Reference Example 3 were placed in a fully jacketed separable flask equipped with a thermometer and a stirring blade. Then, 500 g of toluene and 100 g of demineralized water were added, and the internal temperature was raised to 80°C. 50% by mass of sulfuric acid was added and mixed to neutralize. The stirring was stopped, and the mixture was allowed to stand and separate, after which the lower aqueous phase was removed, and organic phase 1 was obtained.

[0247] The obtained organic phase 1 was cooled from 80° C. to 10° C. to obtain a slurry liquid 1. The obtained slurry liquid 1 was filtered using a vacuum filter to obtain 120 g of a cake A.

[0248] The obtained cake A was placed in a fully jacketed separable flask equipped with a thermometer and a stirring blade, after which 700 g of toluene and 100 g of demineralized water were added, and the internal temperature was raised to 80°C while mixing. The stirring was stopped and the mixture was allowed to stand, after which the lower aqueous phase was removed to obtain organic phase 2. The obtained organic phase 2 was washed four times with 100 g of demineralized water to obtain organic phase 3. The temperature of organic phase 3 was lowered from 80°C to 10°C to obtain slurry liquid 2. The obtained slurry liquid 2 was filtered using a vacuum filter to obtain 110 g of cake B.

[0249] Cake B was dried using a rotary evaporator to obtain 95 g of bisphenol A. The melt color of the obtained bisphenol A was APHA89, and the content of components thought to be undecomposed substances and stabilizers derived from the polycarbonate resin was 0.08 mass %.

[0250] [Example 14] A 45 mL glass reactor equipped with a stirrer and a distillation tube was charged with 10.00 g (0.04 mol of bisphenol A) of the bisphenol A obtained in Examples 5 to 7, 9.95 g (0.05 mol) of diphenyl carbonate, and 18 μL of a 400 ppm by mass aqueous cesium carbonate solution. The glass reactor was depressurized to approximately 100 Pa, and then the pressure was returned to atmospheric pressure with nitrogen. This operation was repeated three times to replace the inside of the reactor with nitrogen. The reactor was then immersed in an oil bath at 220°C, and the contents were dissolved.

[0251] The stirrer was rotated at 100 revolutions per minute, and the pressure inside the reaction vessel was reduced from 101.3 kPa to 13.3 kPa absolute pressure over 40 minutes while distilling off phenol, which was a by-product of the oligomerization reaction of bisphenol A and diphenyl carbonate inside the reaction vessel. Subsequently, the pressure inside the reaction vessel was maintained at 13.3 kPa, and the transesterification reaction was carried out for 80 minutes while further distilling off phenol.

[0252] Thereafter, the temperature outside the reactor was raised to 290°C, and the pressure inside the reactor was reduced from 13.3 kPa to 399 Pa absolute over 40 minutes, and the distilled phenol was removed from the system.

[0253] Thereafter, the absolute pressure in the reaction vessel was reduced to 30 Pa, and the polycondensation reaction was carried out. When the agitator in the reaction vessel reached a predetermined agitation power, the polycondensation reaction was terminated. The time from raising the temperature to 290°C to completing the polymerization was 120 minutes.

[0254] The reactor was then pressurized with nitrogen to an absolute pressure of 101.3 kPa, and then the pressure was increased to a gauge pressure of 0.2 MPa. The polycarbonate resin was extracted from the reactor to obtain a polycarbonate resin having a viscosity average molecular weight (Mv) of 26,300.

Claims

1. A step (A1) of decomposing a polycarbonate resin to obtain a crude solution a1 containing low-boiling components and bisphenol A, wherein the temperature at which the polycarbonate resin is decomposed is 150°C or lower; a step (A2) of distilling off the low-boiling components from the crude solution a1 obtained in the step (A1) to obtain a crude solution a2 containing bisphenol A, wherein the content of bisphenol A contained in the crude solution a2 (mass of bisphenol A / mass of crude solution a2×100(%)) is 10 mass% or more and less than 90 mass%; a step (A3) of distilling the crude solution a2 obtained in the step (A2) while decomposing the bisphenol A contained in the crude solution a2 or after decomposing the bisphenol A to recover a distillate a3 containing isopropenylphenol and phenol, wherein the temperature for decomposing the bisphenol A is higher than 150°C and lower than 250°C; A method for producing an isopropenylphenol-containing solution comprising:

2. 2. The method for producing an isopropenylphenol-containing solution according to claim 1, wherein the distillate a3 in the step (A3) contains isopropenylphenol in an amount of 1.0 mass% or more and 59 mass% or less.

3. A method for producing an isopropenylphenol-containing solution described in claim 1 or 2, wherein the crude solution a2 is a composition that is liquid at 40°C or higher.

4. The method for producing an isopropenylphenol-containing solution according to any one of claims 1 to 3, wherein the distillation in the step (A3) is carried out while extracting a portion of the non-volatile liquid to the outside of the system.

5. A method for producing a bisphenol A-containing solution, comprising contacting a distillate a3 obtained by the production method according to any one of claims 1 to 4 with an acid catalyst to recombine isopropenylphenol and phenol to produce bisphenol A, thereby obtaining a reaction solution a4 containing bisphenol A.

6. A method for producing bisphenol A, comprising a step (A5) of purifying the reaction solution a4 obtained by the method for producing a bisphenol A-containing solution according to claim 5 to obtain bisphenol A.

7. a step (B1) of dehydrating and condensing acetone and phenol in the presence of an acid catalyst to obtain a reaction liquid b1 containing bisphenol A; a step (B2) of distilling off unreacted acetone and water from the reaction liquid b1 obtained in the step (B1) to obtain a concentrated liquid b2; a step (B3) of crystallizing the concentrated liquid b2 obtained in the step (B2) to obtain a slurry liquid, and subjecting the slurry liquid to solid-liquid separation to separate it into a mother liquid b3 and a cake containing crystals of an adduct of bisphenol A and phenol; a step (B4) of purifying the cake obtained in the step (B3) to obtain bisphenol A; a step (B6A) of distilling the mother liquor b3 obtained in the step (B3) while or after decomposing bisphenol A contained in the mother liquor b3, and recovering a distillate b6 containing isopropenylphenol and phenol; a step (B7) of contacting the distillate b6 with an acid catalyst to recombine isopropenylphenol and phenol to produce bisphenol A, thereby obtaining a reaction solution b7 containing bisphenol A; and a portion of the mother liquor b3 obtained in the step (B3) is circulated and supplied to the step (B1) and / or the step (B2); A method for producing bisphenol A, comprising supplying the reaction liquid b7 obtained in the step (B7) to the step (B1) and / or the step (B2), A method for producing bisphenol A, comprising supplying the reaction liquid a4 obtained by the method for producing a bisphenol A-containing solution according to claim 5 to one or more steps selected from the group consisting of the step (B1), the step (B2), and the step (B3).

8. a step (B1) of dehydrating and condensing acetone and phenol in the presence of an acid catalyst to obtain a reaction liquid b1 containing bisphenol A; a step (B2) of distilling off unreacted acetone and water from the reaction liquid b1 obtained in the step (B1) to obtain a concentrated liquid b2; a step (B3) of crystallizing the concentrated liquid b2 obtained in the step (B2) to obtain a slurry liquid, and subjecting the slurry liquid to solid-liquid separation to separate it into a mother liquid b3 and a cake containing crystals of an adduct of bisphenol A and phenol; a step (B4) of purifying the cake obtained in the step (B3) to obtain bisphenol A; a step (B5) of isomerizing the mother liquor b3 obtained in the step (B3), followed by crystallization and solid-liquid separation to separate the mother liquor b5 and a cake containing crystals of an adduct of bisphenol A and phenol; a step (B6B) of distilling the mother liquor b5 obtained in the step (B5) while or after decomposing bisphenol A contained in the mother liquor b5, to recover a distillate b6 containing isopropenylphenol and phenol; a step (B7) of contacting the distillate b6 with an acid catalyst to recombine isopropenylphenol and phenol to produce bisphenol A, thereby obtaining a reaction solution b7 containing bisphenol A; and a portion of the mother liquor b3 obtained in the step (B3) is circulated and supplied to the step (B1) and / or the step (B2); A method for producing bisphenol A, comprising supplying the reaction liquid b7 obtained in the step (B7) to the step (B1) and / or the step (B2), A method for producing bisphenol A, comprising supplying the reaction liquid a4 obtained by the method for producing a bisphenol A-containing solution according to claim 5 to one or more steps selected from the group consisting of the step (B1), the step (B2), and the step (B3).

9. 9. The method for producing bisphenol A according to claim 7 or 8, wherein the reaction liquid a4 is mixed with one or more selected from the group consisting of the reaction liquid b1, the concentrated liquid b2, the mother liquid b3, and the reaction liquid b7, and the mixture is supplied to one or more steps selected from the group consisting of the step (B1), the step (B2), and the step (B3).

10. a step (B1) of dehydrating and condensing acetone and phenol in the presence of an acid catalyst to obtain a reaction liquid b1 containing bisphenol A; a step (B2) of distilling off unreacted acetone and water from the reaction liquid b1 obtained in the step (B1) to obtain a concentrated liquid b2; a step (B3) of crystallizing the concentrated liquid b2 obtained in the step (B2) to obtain a slurry liquid, and subjecting the slurry liquid to solid-liquid separation to separate it into a mother liquid b3 and a cake containing crystals of an adduct of bisphenol A and phenol; a step (B4) of purifying the cake obtained in the step (B3) to obtain bisphenol A; a step (B6A) of distilling the mother liquor b3 obtained in the step (B3) while or after decomposing bisphenol A contained in the mother liquor b3, and recovering a distillate b6 containing isopropenylphenol and phenol; a step (B7) of contacting the distillate b6 with an acid catalyst to recombine isopropenylphenol and phenol to produce bisphenol A, thereby obtaining a reaction solution b7 containing bisphenol A; and a portion of the mother liquor b3 is circulated and supplied to the step (B1) and / or the step (B2); The reaction liquid b7 is supplied to the step (B1) and / or the step (B2), A method for producing bisphenol A, comprising supplying the distillate a3 obtained by the method for producing an isopropenylphenol-containing solution according to any one of claims 1 to 4 to the step (B7).

11. a step (B1) of dehydrating and condensing acetone and phenol in the presence of an acid catalyst to obtain a reaction liquid b1 containing bisphenol A; a step (B2) of distilling off unreacted acetone and water from the reaction liquid b1 obtained in the step (B1) to obtain a concentrated liquid b2; a step (B3) of crystallizing the concentrated liquid b2 obtained in the step (B2) to obtain a slurry liquid, and subjecting the slurry liquid to solid-liquid separation to separate it into a mother liquid b3 and a cake containing crystals of an adduct of bisphenol A and phenol; a step (B4) of purifying the cake obtained in the step (B3) to obtain bisphenol A; a step (B5) of isomerizing the mother liquor b3 obtained in the step (B3), followed by crystallization and solid-liquid separation to separate the mother liquor b5 and a cake containing crystals of an adduct of bisphenol A and phenol; a step (B6B) of distilling the mother liquor b5 obtained in the step (B5) while or after decomposing bisphenol A contained in the mother liquor b5, to recover a distillate b6 containing isopropenylphenol and phenol; a step (B7) of contacting the distillate b6 with an acid catalyst to recombine isopropenylphenol and phenol to produce bisphenol A, thereby obtaining a reaction solution b7 containing bisphenol A; and a portion of the mother liquor b3 is circulated and supplied to the step (B1) and / or the step (B2); The reaction liquid b7 is supplied to the step (B1) and / or the step (B2), A method for producing bisphenol A, comprising supplying the distillate a3 obtained by the method for producing an isopropenylphenol-containing solution according to any one of claims 1 to 4 to the step (B7).

12. The method for producing bisphenol A according to claim 10 or 11, wherein the distillate a3 is mixed with the distillate b6 and supplied to the step (B7).

13. A method for producing a polycarbonate resin, comprising obtaining bisphenol A through the method for producing bisphenol A according to any one of claims 6 to 12, and then using the bisphenol A to produce a polycarbonate resin.

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