Method for producing bisphenol, and method for producing recycled polycarbonate resin

Abstract

Provided is a method for producing bisphenol, the method being capable of obtaining bisphenol which has excellent purity and does not contain other resins derived from a coating layer, an alloy material, or the like. The method for producing bisphenol according to the present invention, with which bisphenol is obtained by removing resins other than polycarbonate resins from a mixed solution containing bisphenol and the other resins. The production method has a step 1 for precipitating bisphenol from an aromatic monoalcohol-containing solution in which the bisphenol and the other resins are dissolved in a solvent including an aromatic monoalcohol, thereby obtaining a slurry of the bisphenol, and subjecting the bisphenol slurry to solid-liquid separation to obtain a crude cake of the bisphenol and a base liquid.

Description

[Technical Field]

[0001] This invention relates to a method for producing bisphenol. Furthermore, this invention relates to a method for producing recycled polycarbonate resin using said bisphenol as a raw material. [Background technology]

[0002] Due to its superior functionality and properties, plastic is indispensable in modern society and is produced and consumed in large quantities not only in Japan but all over the world. For sustainable development, the recycling of plastic resources after consumption is important, and there are three main methods for achieving this: material recycling, which regenerates plastic into raw materials for plastic products; chemical recycling, which regenerates plastic into chemical raw materials; and thermal recycling, which uses plastic as an energy source.

[0003] In Japan, thermal recycling has the highest utilization rate of waste plastics among all recycling laws. The amount of heat generated when burning plastics is comparable to that of coal or oil, and this heat can be effectively utilized for power generation and other purposes. However, in Europe and the United States, thermal recycling is often not considered recycling, and there is a demand for further promotion of material recycling and chemical recycling. Polycarbonate resin, which is used in a wide range of fields due to its transparency, mechanical properties, flame retardancy, dimensional stability, and electrical properties, is no exception.

[0004] Polycarbonate resin offers excellent processability and durability, as well as high transparency. Therefore, it is used not only in the casings of household electrical appliances and optical recording discs (such as CDs), but also in automotive headlamp lenses, carport roofing materials, and highway sound barriers, all of which are used outdoors for extended periods. Many of these outdoor polycarbonate resin products are coated with acrylic resin or similar materials to improve surface scratch resistance. Furthermore, many alloy materials with improved performance are available on the market, which are made by compounding polycarbonate resin with other resins other than polycarbonate resin, such as polyester resin and ABS resin (hereinafter sometimes simply referred to as "other resins").

[0005] Numerous methods for material and chemical recycling of polycarbonate resin have been reported. Examples of material recycling include a method (Patent Document 1) in which an optical recording disc is treated with an alkaline aqueous solution to remove the surface metal coating and recover the polycarbonate resin substrate, and a method (Patent Document 2) in which an optical recording disc is dissolved in a solvent and then precipitated using a mixture of water and alcohol to recover only the polycarbonate resin.

[0006] Furthermore, known chemical recycling methods include hydrolyzing waste polycarbonate resin to recover it as an alkaline aqueous solution containing the sodium salt of bisphenol (Patent Document 3), alkolisys forming an optical recording disc to recover bisphenol and dialkyl carbonate (Patent Document 4), and phenolysis forming a waste polycarbonate resin to recover bisphenol and diphenyl carbonate (Patent Document 5). [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2001-310970 [Patent Document 2] Japanese Patent Publication No. 2009-84538 [Patent Document 3] Japanese Patent Publication No. 2005-179460 [Patent Document 4] Japanese Patent Publication No. 2001-160243 [Patent Document 5] Japanese Patent Application Publication No. 7-207059 [Overview of the Initiative] [Problems that the invention aims to solve]

[0008] Material recycling is the common method for recycling polycarbonate resin products, but it has the drawback of limiting the uses of recycled products. For example, polycarbonate resin products with a coating layer such as acrylic resin produce silver streaks during injection molding when material recycled, making them difficult to recycle for use in building materials or automotive headlamp lenses where transparency is required. Therefore, many polycarbonate resin products that are material recycled are colored and recycled as opaque materials.

[0009] Furthermore, material recycling does not allow for the separation of polycarbonate resin from colorants and other resins. Therefore, in order to obtain resin products with the desired quality and performance, the only option is to set a low mixing ratio of waste polycarbonate resin, which is inefficient from the perspective of resource recycling. For these reasons, it is preferable to purify and recover waste polycarbonate resin mixed with colorants and other resins as monomers through chemical recycling.

[0010] However, when we attempted to obtain bisphenol by depolymerizing waste polycarbonate resin mixed with other resins, the contamination of the obtained bisphenol with polymers became apparent. Furthermore, it was found that bisphenol containing other resins was difficult to dry because the solvent did not evaporate easily. The inclusion of these polymers is undesirable because it not only reduces the purity of bisphenol but can also cause undesirable side reactions, discoloration, and operational problems due to gas generation when manufacturing recycled polycarbonate resin using bisphenol as a raw material. Therefore, there has been a need for a bisphenol purification method that can efficiently separate and remove polymers mixed into waste polycarbonate resin from bisphenol.

[0011] This invention has been made in view of the above-mentioned conventional circumstances, and aims to provide a method for producing bisphenol that does not contain other resins derived from coating layers, alloy materials, etc., and that can produce bisphenol with excellent purity. It also aims to provide a method for producing recycled polycarbonate resin using said bisphenol as a raw material. [Means for solving the problem]

[0012] The inventors of this invention have conducted extensive research to solve the above problems and have found that the following invention is suitable for the above purpose, leading to the present invention. That is, the present invention relates to the following invention.

[0013] <1> A method for producing bisphenol, comprising step 1: removing a resin other than bisphenol and polycarbonate resin (hereinafter referred to as "other resin") from a mixed solution containing bisphenol and polycarbonate resin, wherein step 1 involves precipitating bisphenol from an aromatic monoalcohol-containing solution obtained by dissolving the bisphenol and the other resin in an aromatic monoalcohol-containing solvent, thereby obtaining a slurry of the bisphenol, and then performing solid-liquid separation of the bisphenol slurry to obtain a crude cake of the bisphenol and a mother liquor. <2> Before precipitating the bisphenol, the mixed solution or the aromatic monoalcohol-containing solution is subjected to solid-liquid separation to obtain a homogeneous solution. <1> A method for producing bisphenol as described above. <3> Prior to step 1, the process includes a depolymerization step in which the polycarbonate resin in a polycarbonate resin composite containing the polycarbonate resin and the other resin is depolymerized to obtain a decomposition solution containing the bisphenol and the other resin, wherein the mixed solution is the decomposition solution. <1> or <2> A method for producing bisphenol as described above. <4> The mixed solution is obtained by carrying out the depolymerization in the presence of the aromatic monoalcohol in the depolymerization step, and the aromatic monoalcohol-containing solution is the mixed solution. <3> A method for producing bisphenol as described above. <5> The mixed solution is obtained by performing the depolymerization in the absence of the aromatic monoalcohol in the depolymerization step, and the aromatic monoalcohol-containing solution is obtained by solvent substitution of the solvent of the obtained mixed solution with the aromatic monoalcohol. The method for producing bisphenol according to <3> above. <6> The method for producing bisphenol according to any one of <3> to <5> above, wherein the polycarbonate resin composite is one or more selected from the group consisting of the following (c1) to (c8). (c1) A molded body of a polymer alloy of the polycarbonate resin and the other resin (c2) A resin molded body in which the other resin is coated on the surface of the molded body of the polycarbonate resin (c3) A resin molded body in which a polymer alloy of the polycarbonate resin and the other resin is coated on the surface of the molded body of the polycarbonate resin (c4) A resin molded body in which the other resin is coated on the surface of the molded body of the polymer alloy of the polycarbonate resin and the other resin (c5) A resin molded body in which a polymer alloy of the polycarbonate resin and the other resin is coated on the surface of the molded body of the polymer alloy of the polycarbonate resin and the other resin (c6) A resin molded body in which the polycarbonate resin is coated on the surface of the molded body of the polymer alloy of the polycarbonate resin and the other resin (c7) A resin molded body in which the polycarbonate resin is coated on the surface of the molded body of the other resin (c8) A resin molded body in which a polymer alloy of the polycarbonate resin and the other resin is coated on the surface of the molded body of the other resin <7> The method for producing bisphenol according to any one of <1> to <6> above, wherein the aromatic monoalcohol contains phenol or cresol. <8> The aromatic monoalcohol is phenol, and in step 1, the bisphenol is precipitated as an adduct crystal consisting of bisphenol and phenol, and a crude cake of the adduct crystal consisting of bisphenol and phenol is obtained. <1> from <7> A method for producing bisphenol as described in any of the following. <9> The molar ratio of the aromatic monoalcohol content to the bisphenol content in the aromatic monoalcohol-containing solution that precipitates bisphenol is 1.0 or more (for example, 1.0 or more and 10 or less), <1> from <8> A method for producing bisphenol as described in any of the following. <10> The process includes step 2, which involves supplying a washing solution to the crude bisphenol cake after step 1, washing the crude bisphenol cake, and obtaining a refined bisphenol cake. <1> from <9> A method for producing bisphenol as described in any of the following. <11> The washing solution is at least one selected from the group consisting of aromatic monoalcohols, aliphatic monoalcohols, ketones, aromatic hydrocarbons, aliphatic hydrocarbons, and water. <10> A method for producing bisphenol as described above. <12> The process involves dissolving or melting the crude bisphenol cake or the refined cake obtained by washing the crude cake in a solvent to obtain a bisphenol solution, and then contacting the bisphenol solution with a solid adsorbent to obtain an adsorption-purified solution. <1> from <11> A method for producing bisphenol as described in any of the following. <13> The other resin is at least one selected from the group consisting of acrylic resin, polyethylene terephthalate, polybutylene terephthalate, ABS resin, polyamide, phenolic resin, polyurethane, polylactic acid, and silicone resin. <1> from <12> A method for producing bisphenol as described in any of the following. <14> The bisphenol is 2,2-bis(4-hydroxyphenyl)propane, <1> from <13> A method for producing bisphenol as described in any of the following. <15> The aforementioned <1> from <14> A method for producing recycled polycarbonate resin, comprising the steps of: obtaining bisphenol by a method for producing bisphenol described in any of the above; and producing recycled polycarbonate resin using a bisphenol raw material containing the obtained bisphenol.

[0014] <x1>The washing solution is at least one selected from the group consisting of phenol, cresol, methanol, ethanol, acetone, cyclohexanone, benzene, toluene, xylene, hexane, heptane, cyclohexane, and water. <11> A method for producing bisphenol as described above. <x2>The process comprises a washing step in which the adsorption purification solution is mixed with water, then phase-separated into an organic phase containing bisphenol and an aqueous phase, the aqueous phase is removed to obtain the organic phase, and a crystallization step in which bisphenol is precipitated from the organic phase obtained in the washing step, wherein the washing step is repeated until the electrical conductivity of the removed aqueous phase is 10 μS / cm or less, and then the crystallization step is performed. <12> A method for producing bisphenol as described above. <x3>The process comprises: a washing step in which the adsorption purification solution is mixed with water, then phase-separated into an organic phase containing bisphenol and an aqueous phase, the aqueous phase is removed to obtain the organic phase; a concentration step in which the organic solvent is removed from the organic phase to obtain molten bisphenol; and a granulation step in which the molten bisphenol is granulated to obtain granules, wherein the washing step is repeated until the electrical conductivity of the removed aqueous phase is 10 μS / cm or less, and then the concentration step is performed. <12> A method for producing bisphenol as described above. <x4>The process further comprises a bisphenol synthesis step of obtaining the bisphenol from a ketone or aldehyde and an aromatic monoalcohol, which includes the following steps A to D, and the adsorption purification solution is supplied to one or more of the following steps A to D. <12> A method for producing bisphenol as described above. Step A: A step in which the ketone or aldehyde and the aromatic monoalcohol are dehydrated and condensed in the presence of an acid catalyst to obtain a reaction solution A containing bisphenol. Step B: A step in which unreacted ketones or aldehydes and water are removed from reaction solution A by distillation to obtain concentrated solution B. Step C: A step in which the slurry obtained by crystallizing the concentrated liquid B is subjected to solid-liquid separation to separate it into mother liquor C and cake c. Step D: A step of purifying the cake c to obtain the bisphenol. [Effects of the Invention]

[0015] The present invention provides a method for producing bisphenol with excellent purity. Furthermore, it provides a method for producing recycled polycarbonate resin using the bisphenol as a raw material. [Brief explanation of the drawing]

[0016] [Figure 1] This is a flow chart showing an example of a method for producing bisphenol according to the present invention. [Figure 2] This flowchart shows another example of the method for producing bisphenol according to the present invention. [Figure 3] This flowchart shows another example of the method for producing bisphenol according to the present invention. [Figure 4] This flowchart shows another example of the method for producing bisphenol according to the present invention. [Figure 5] Figure 4 is a flowchart illustrating the method for producing bisphenol in more detail. [Modes for carrying out the invention]

[0017] The embodiments of the present invention will be described in detail below, but the description of the constituent elements described below is just one example of how the present invention can be carried out, and the present invention is not limited to the following description as long as it does not exceed the gist of the invention. In this specification, when the expression "~" is used, it is used to mean an expression that includes the numerical value or physical property value before and after it.

[0018] <Method for producing bisphenol> The present invention relates to a method for producing bisphenol, which involves removing a resin other than bisphenol and polycarbonate resin (hereinafter referred to as "the other resin") from a mixed solution containing the other resin, and comprising step 1: precipitating bisphenol from an aromatic monoalcohol-containing solution obtained by dissolving the bisphenol and the other resin in an aromatic monoalcohol-containing solvent to obtain a bisphenol slurry, and then performing solid-liquid separation of the bisphenol slurry to obtain a crude bisphenol cake and a mother liquor (hereinafter sometimes referred to as "the method for producing bisphenol of the present invention").

[0019] When attempting to obtain bisphenol from a mixed solution containing bisphenol and other resins, the resulting bisphenol is easily contaminated with the other resins, making it difficult to obtain high-purity bisphenol. However, the inventors have discovered that even when other resins are present during bisphenol precipitation, bisphenol can be precipitated while suppressing the adhesion of dissolved other resins by precipitation in the presence of an aromatic monoalcohol. The bisphenol production method of the present invention makes it possible to obtain bisphenol with excellent purity. The resulting bisphenol has high polymerization activity, and a polycarbonate resin with a desired molecular weight and excellent color tone can be obtained.

[0020] The present invention provides a method for producing bisphenol, comprising the step of obtaining bisphenol by removing other resins from a mixed solution containing bisphenol and other resins. The step of obtaining bisphenol by removing other resins from a mixed solution comprises Step 1. Step 1 is a crude crystallization step in which bisphenol is precipitated from an aromatic monoalcohol-containing solution in which bisphenol and other resins are dissolved in an aromatic monoalcohol-containing solvent, a bisphenol slurry is obtained, and then the bisphenol slurry is subjected to solid-liquid separation to obtain a crude bisphenol cake and a mother liquor.

[0021] (mixed solution) The mixed solution is a solution containing bisphenol and other resins. For example, the decomposition solution obtained by depolymerizing the polycarbonate resin in the polycarbonate resin composite described later can be used as the mixed solution.

[0022] In the present invention, "other resin" refers to a polymer other than polycarbonate resin with a molecular weight of 10,000 or more. Examples of other resins included in the mixed solution include polypropylene, polyethylene, polystyrene, acrylic resin, polyethylene terephthalate, polybutylene terephthalate, ABS resin, polyamide, phenolic resin, polyurethane, polylactic acid, and silicone resin. Furthermore, in the present invention, "other resin" includes at least one other resin that dissolves in a solvent containing an aromatic monoalcohol. This other resin that dissolves in a solvent containing an aromatic monoalcohol is removed in step 1. Preferably, the other resin that dissolves in such a solvent containing an aromatic monoalcohol is at least one selected from the group consisting of acrylic resin, polyethylene terephthalate, polybutylene terephthalate, ABS resin, polyamide, phenolic resin, polyurethane, polylactic acid, and silicone resin.

[0023] Depending on the solvent contained in the mixed solution, the mixed solution and the aromatic monoalcohol-containing solution may be the same or different. If the mixed solution contains an aromatic monoalcohol and bisphenol and other resins are dissolved in it, the mixed solution can be used as an aromatic monoalcohol-containing solution and may be used directly for bisphenol precipitation, or it may be concentrated, diluted, or insoluble matter removed before bisphenol precipitation. If the mixed solution does not contain an aromatic monoalcohol, an aromatic monoalcohol-containing solution is prepared by solvent substitution of the mixed solution with an aromatic monoalcohol.

[0024] Furthermore, it is preferable to precipitate bisphenol in a homogeneous solution containing aromatic monoalcohols. Therefore, if there are insoluble substances in the mixed solution or the aromatic monoalcohol-containing solution, it is preferable to separate the mixed solution or the aromatic monoalcohol-containing solution into a homogeneous solution before precipitation of bisphenol, and then precipitate bisphenol from the homogeneous solution. When preparing an aromatic monoalcohol-containing solution by solvent substitution of the mixed solution, solid-liquid separation may be performed before solvent substitution, after solvent substitution, or both before and after solvent substitution.

[0025] The mixed solution may contain, in addition to other resins that dissolve in the solvent containing the aromatic monoalcohol, resins that do not dissolve in the solvent containing the aromatic monoalcohol. Resins that do not dissolve in the solvent containing the aromatic monoalcohol can be removed, for example, by solid-liquid separation through filtration.

[0026] (Aromatic monoalcohol-containing solution) Aromatic monoalcohol-containing solutions are solutions in which bisphenol and other resins are dissolved in a solvent containing an aromatic monoalcohol.

[0027] (Bisphenol) Typical bisphenols found in aromatic monoalcohol-containing solutions are those represented by the following formula (II).

[0028] [ka]

[0029] In equation (II), R 1 ~R 4 Each of these is independently a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, or an aryl group. For example, a hydrogen atom, a fluoro group, a chloro group, a bromo group, an iodo group, a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, an i-butyl group, a t-butyl group, an n-pentyl group, an i-pentyl group, an n-hexyl group, an n-heptyl group, an n-octyl group, an n-nonyl group, an n-decyl group, an n-undecyl group, an n-dodecyl group, a methoxy group, an ethoxy group, an n-propoxy group, an i-propoxy group, an n-butoxy group, an i-butoxy group, or a t-butoxy group. Examples include n-pentyloxy group, i-pentyloxy group, n-hexyloxy group, n-heptyloxy group, n-octyloxy group, n-nonyloxy group, n-decyloxy group, n-undecyloxy group, n-dodecyloxy group, cyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group, cycloheptyl group, cyclooctyl group, cyclododecyl group, benzyl group, phenyl group, tolyl group, and 2,6-dimethylphenyl group.

[0030] In equation (II), R 5 and R 6 Each of these is independently a hydrogen atom, an alkyl group, an alkoxy group, or an aryl group. For example, hydrogen atom, methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, i-butyl group, t-butyl group, n-pentyl group, i-pentyl group, n-hexyl group, n-heptyl group, n-octyl group, 2-ethylhexyl group, n-nonyl group, n-decyl group, n-undecyl group, n-dodecyl group, methoxy group, ethoxy group, n-propoxy group, i-propoxy group, n-butoxy group, i-butoxy group, t-butoxy group, n-pel Examples include phthaloxy group, i-pentyloxy group, n-hexyloxy group, n-heptyloxy group, n-octyloxy group, n-nonyloxy group, n-decyloxy group, n-undecyloxy group, n-dodecyloxy group, cyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group, cycloheptyl group, cyclooctyl group, cyclododecyl group, benzyl group, phenyl group, tolyl group, and 2,6-dimethylphenyl group.

[0031] In equation (II), R 5 and R 6 The two groups may bond or bridge with each other to form a cycloalkylidene group, a fluorenylidene group (fluorene 9,9-diyl group), a xanthenylidene group (xanthene 9,9-diyl group), a thioxanthenylidene group (thioxanthene 9,9-diyl group), and the like. Examples of cycloalkylidene groups include cyclopropylidene, cyclobutylidene, cyclopentylidene, cyclohexylidene, 3,3,5-trimethylcyclohexylidene, cycloheptylidene, cyclooctylidene, cyclononylidene, cyclodecylidene, cycloundecylidene, and cyclododecylidene.

[0032] Specifically, the bisphenols represented by formula (II) include 2,2-bis(4-hydroxyphenyl)propane, 2,2-bis(4-hydroxy-3-methylphenyl)propane, 2,2-bis(4-hydroxy-3,5-dimethylphenyl)propane, 1,1-bis(4-hydroxy-3-methylphenyl)cyclohexane, 9,9-bis(4-hydroxy-3-methylphenyl)fluorene, 3,3-bis(4-hydroxyphenyl)pentane, 3,3-bis(4-hydroxy-3-methylphenyl)pentane, and 2,2-bis(4- Examples of bisphenols include, but are not limited to, hydroxyphenyl)pentane, 2,2-bis(4-hydroxy-3-methylphenyl)pentane, 3,3-bis(4-hydroxyphenyl)heptane, 3,3-bis(4-hydroxy-3-methylphenyl)heptane, 2,2-bis(4-hydroxyphenyl)heptane, 2,2-bis(4-hydroxy-3-methylphenyl)heptane, 4,4-bis(4-hydroxyphenyl)heptane, and 4,4-bis(4-hydroxy-3-methylphenyl)heptane.

[0033] Among these, any bisphenol selected from the group consisting of 2,2-bis(4-hydroxyphenyl)propane, 2,2-bis(4-hydroxy-3-methylphenyl)propane, 2,2-bis(4-hydroxy-3,5-dimethylphenyl)propane, and 1,1-bis(4-hydroxy-3-methylphenyl)cyclohexane is preferred, and in particular, 2,2-bis(4-hydroxyphenyl)propane (hereinafter referred to as "BPA" or "bisphenol A") is preferred.

[0034] (Aromatic monoalcohols) Aromatic monoalcohols included in the aromatic monoalcohol-containing solution include phenol, cresol, and xylenol. The aromatic monoalcohol preferably contains phenol and / or cresol, and more preferably contains phenol.

[0035] The aromatic monoalcohol-containing solution may contain solvents other than the aromatic monoalcohol, as long as bisphenol can be dissolved in it. The molar ratio of aromatic monoalcohol to bisphenol (moles of aromatic monoalcohol / moles of bisphenol) can be 0.5 or higher, 0.6 or higher, 0.7 or higher, etc., and is preferably 1.0 or higher. There is no particular upper limit on the amount of aromatic monoalcohol in the aromatic monoalcohol-containing solution, but since bisphenol precipitation becomes difficult and yield decreases, it is preferably 20 or less, more preferably 15 or less, and even more preferably 10 or less. Therefore, the molar ratio of aromatic monoalcohol to bisphenol is preferably 0.5 to 20, more preferably 1.0 to 20, even more preferably 1.0 to 15, and particularly preferably 1.0 to 10.

[0036] (Precipitation of bisphenol) In step 1, bisphenol is first precipitated from the aromatic monoalcohol-containing solution to obtain a bisphenol slurry. The method for precipitating bisphenol can be a general method of precipitating crystals from a solution, and there are no particular limitations, but a method of precipitating bisphenol by cooling is preferred. The cooling conditions are not particularly limited, but in order to efficiently precipitate bisphenol, it is preferable to set the temperature 20°C to 100°C lower than the temperature of the aromatic monoalcohol-containing solution used in step 1. The aromatic monoalcohol-containing solution used in step 1 is usually around 40°C to 120°C to prevent solidification, so it is preferable to cool it to -20°C to 60°C, and more preferably to 0°C to 50°C, in order to precipitate bisphenol. Cooling to such temperatures makes it possible to obtain a slurry with good fluidity.

[0037] Bisphenol may be precipitated as bisphenol crystals, or as adduct crystals of bisphenol and a solvent. In the case of bisphenol A, it is preferable to use phenol as the aromatic monoalcohol to precipitate adduct crystals consisting of bisphenol A and phenol, thereby obtaining a crude cake of adduct crystals. Precipitating as adduct crystals makes it difficult for other resins to adhere to the precipitated crystals, improving the efficiency of removing other resins dissolved in the phenol-containing solvent.

[0038] (solid-liquid separation) In step 1, a bisphenol slurry is obtained, and then the bisphenol slurry is subjected to solid-liquid separation to obtain a crude bisphenol cake and a mother liquor. Solid-liquid separation can be performed by known means such as filtration or centrifugation. For example, solid-liquid separation can be performed using a horizontal belt filter, rotary vacuum filter, rotary pressure filter, centrifugal filter, centrifugal sedimentation separator, or a hybrid type of centrifuge (screen ball decanter) thereof.

[0039] (Process 2) The present invention preferably includes a step 2, after step 1, in which a washing solution is supplied to the crude bisphenol cake to wash the crude bisphenol cake and obtain a refined bisphenol cake. By washing away other resins and the like adhering to the crude cake with the washing solution, the purity of the bisphenol can be further improved.

[0040] (Cleaning solution) The cleaning solution may include at least one selected from the group consisting of aromatic monoalcohols, aliphatic monoalcohols, ketones, aromatic hydrocarbons, aliphatic hydrocarbons, and water.

[0041] Specifically, the washing solution is preferably at least one selected from the group consisting of phenol, cresol, methanol, ethanol, acetone, cyclohexanone, benzene, toluene, xylene, hexane, heptane, cyclohexane, and water.

[0042] The washing temperature is approximately 10°C to 80°C, preferably 15°C or higher, and more preferably 20°C or higher. The crude cake can be washed within the above temperature range by supplying a washing solution heated to a desired temperature to the crude cake, or by supplying a washing solution to a crude cake that has been heated to a desired temperature.

[0043] The amount of washing solution used per batch for the crude bisphenol cake (amount of washing solution used per batch (g) / mass of crude cake (g)) is preferably 0.5 or more, and more preferably 1.0 or more.

[0044] Washing methods include supplying a washing solution to the crude cake while filtering or centrifuging, or mixing the crude cake with the washing solution and then separating the solid and liquid again. Washing may be performed multiple times, but too many times will reduce the yield of bisphenol, so it is usually limited to five times or less, and three times or less is preferable.

[0045] Furthermore, the present invention preferably includes a step of dissolving or melting the crude bisphenol cake or the refined cake obtained by washing the crude cake in a solvent to obtain a bisphenol solution, and then contacting the bisphenol solution with a solid adsorbent to obtain an adsorption-purified solution. This makes it possible to obtain bisphenol with even higher purity. The method for washing the crude cake to obtain the refined cake is the same as in step 2 above.

[0046] The method for producing bisphenol according to the present invention will be described in detail below, using the case in which a depolymerization step is performed before step 1 as an example.

[0047] <Method for producing bisphenol (I)> Figure 1 is a flow chart showing an example of the method for producing bisphenol according to the present invention. The method for producing bisphenol (I) shown in Figure 1 comprises a depolymerization step, step 1, and step 2. As shown in the flow chart of Figure 1, by performing steps 1 and 2 after the depolymerization step, bisphenol with superior purity can be obtained. In the method for producing bisphenol (I), steps 1 and 2 are performed as a post-process of the depolymerization step of the polycarbonate resin in a polycarbonate resin composite containing polycarbonate resin and other resins. In particular, it is preferable that steps 1 and 2 are performed after the depolymerization step using waste material from the polycarbonate resin composite.

[0048] When polycarbonate resin is depolymerized using polycarbonate resin and polycarbonate resin composites containing other resins as raw materials, other resins coexist with bisphenol in the decomposition solution after depolymerization. As a result, the bisphenol obtained is prone to contamination by these other resins, leading to a low purity of bisphenol.

[0049] Conventionally, the decomposition solution after depolymerization was generally purified by crystallization after reducing the content of aromatic monoalcohols as much as possible in the absence of aromatic monoalcohols, or by operations such as distillation, and then replacing them with organic solvents such as aromatic hydrocarbons. When attempting to obtain a bisphenol cake by crystallization in the presence of aromatic monoalcohols after depolymerization, there is a concern that the bisphenol cake will contain a large amount of aromatic monoalcohols, leading to oxidation and discoloration of the aromatic monoalcohols. Furthermore, since aromatic monoalcohols are soluble in water, the water washing efficiency in the oil-water separation state is poor, so it was thought that the disadvantages outweighed the advantages. However, the inventors have discovered that by depolymerizing the polycarbonate resin in a polycarbonate resin composite containing polycarbonate resin and other resins, and then crystallizing it in the presence of aromatic monoalcohols, it is possible to suppress the adhesion of other resins to the bisphenol crystals, even when other resins are present during crystallization, and to easily separate bisphenol from other resins.

[0050] The method for producing bisphenol of the present invention can obtain highly pure bisphenol even when a polycarbonate resin composite containing a polycarbonate resin and other resins is used as a raw material, particularly when a polycarbonate resin composite such as a coated polycarbonate resin molded body or a molded body of a polymer alloy of a polycarbonate resin and other resins is used as a raw material.

[0051] [Depolymerization step] The depolymerization step is a step performed before step 1, and is a step of depolymerizing the polycarbonate resin in a polycarbonate resin composite (PC + P) containing a polycarbonate resin (PC) and other resins (P) to obtain a decomposition liquid (BP + P) containing bisphenol and other resins.

[0052] (Polycarbonate resin (PC)) The polycarbonate resin contained in the polycarbonate resin composite used as a raw material for depolymerization contains a repeating structural unit of a bisphenol unit and a carbonate unit, and typical examples include polycarbonate resins having a structural unit represented by the following formula (I).

[0053] [Chemical formula]

[0054] Regarding R in the general formula (I) 1 ~R 6 it is synonymous with R in the above formula (II) 1 ~R 6 In the general formula (I), n is the number of structural units. n is not particularly limited, but for example, it is 2 to 1000.

[0055] The constituent units represented by the above general formula (I) are specifically 2,2-bis(4-hydroxyphenyl)propane, 2,2-bis(4-hydroxy-3-methylphenyl)propane, 2,2-bis(4-hydroxy-3,5-dimethylphenyl)propane, 1,1-bis(4-hydroxy-3-methylphenyl)cyclohexane, 9,9-bis(4-hydroxy-3-methylphenyl)fluorene, 3,3-bis(4-hydroxyphenyl)pentane, 3,3-bis(4-hydroxy-3-methylphenyl)pentane, 2,2-bis(4-hydroxyphenyl)pentane, 2 Examples of constituent units derived from bisphenols such as 2-bis(4-hydroxy-3-methylphenyl)pentane, 3,3-bis(4-hydroxyphenyl)heptane, 3,3-bis(4-hydroxy-3-methylphenyl)heptane, 2,2-bis(4-hydroxyphenyl)heptane, 2,2-bis(4-hydroxy-3-methylphenyl)heptane, 4,4-bis(4-hydroxyphenyl)heptane, and 4,4-bis(4-hydroxy-3-methylphenyl)heptane, and carbonate units, include, but are not limited to, these.

[0056] Among these, the polycarbonate resin preferably contains a constituent unit of a bisphenol unit and a carbonate unit, which is derived from any bisphenol selected from the group consisting of 2,2-bis(4-hydroxyphenyl)propane, 2,2-bis(4-hydroxy-3-methylphenyl)propane, 2,2-bis(4-hydroxy-3,5-dimethylphenyl)propane, and 1,1-bis(4-hydroxy-3-methylphenyl)cyclohexane.

[0057] In particular, the constituent units of the bisphenol unit and carbonate unit derived from 2,2-bis(4-hydroxyphenyl)propane (hereinafter referred to as "BPA" or "bisphenol A") (R of the above general formula (I)) 1 ~R 4 is a hydrogen atom, and R 5 , R 6 Since polycarbonate resins containing BPA-type polycarbonate resins (where the group is a methyl group) are easily depolymerized, it is preferable to produce BPA from a polycarbonate resin composite containing BPA-type polycarbonate resin in the bisphenol production method of the present invention.

[0058] (Polycarbonate resin composite containing polycarbonate resin and other resins) As a polycarbonate resin composite (hereinafter sometimes referred to as "PC composite") containing polycarbonate resin and other resins, a molded body of polycarbonate resin alone mixed with other resins as impurities may be used, but it is preferable to use a resin molded body containing polycarbonate resin and other resins. Since it is not possible to separate the polycarbonate resin and other resins by sorting, such a resin molded body is more effective as a raw material for the method of producing bisphenol of the present invention, as it is possible to obtain bisphenol by removing the other resins.

[0059] Examples of resin molded articles containing polycarbonate resin and other resins include the following embodiments (c1) to (c5). (c1) Molded articles of polymer alloys of polycarbonate resin and other resins (c2) A resin molded body in which another resin is coated on the surface of a molded body made of polycarbonate resin alone. (c3) A resin molded body in which a polymer alloy of polycarbonate resin and another resin is coated on the surface of a molded body made of polycarbonate resin alone. (c4) A resin molded body in which the surface of a polymer alloy of polycarbonate resin and other resins is coated with another resin. (c5) A resin molded body in which the surface of a polymer alloy of polycarbonate resin and other resins is coated with a polymer alloy of polycarbonate resin and other resins. (c6) A resin molded body in which polycarbonate resin is coated on the surface of a polymer alloy molded body of polycarbonate resin and other resins. (c7) A resin molded body in which polycarbonate resin is coated on the surface of another resin molded body. (c8) A resin molded body in which a polymer alloy of polycarbonate resin and other resins is coated on the surface of a molded body of another resin.

[0060] Furthermore, the concept of a polymer alloy of polycarbonate resin and other resins includes both mixtures of polycarbonate resin and other resins, and copolymers of polycarbonate resin and other resins. Additionally, a resin molded article containing polycarbonate resin and other resins may be used in combination with a molded article containing polycarbonate resin alone.

[0061] Specifically, examples include molded articles used in applications such as casings for electronic devices and electrical appliances, general merchandise, optical recording media, automotive headlamp covers, lighting lamp covers, automotive interior materials, automotive exterior materials, transport containers, and building materials (carport roofing materials, highway sound barriers, etc.).

[0062] Other resins that can be included in the PC composite include polypropylene, polyethylene, polystyrene, acrylic resin, polyethylene terephthalate, polybutylene terephthalate, ABS resin, polyamide, phenolic resin, polyurethane, polylactic acid, and silicone resin. Furthermore, the PC composite contains at least one other resin that is soluble in a solvent containing an aromatic monoalcohol, and such resins are preferably at least one selected from the group consisting of acrylic resin, polyethylene terephthalate, polybutylene terephthalate, ABS resin, polyamide, phenolic resin, polyurethane, polylactic acid, and silicone resin. The PC composite may contain one of these other resins or two or more of them.

[0063] Polycarbonate resin composites are preferably made from waste plastic (waste material). Waste plastics containing polycarbonate resin and other resins are post-consumer or pre-consumer materials. Post-consumer materials are those that have been incorporated into various products as molded bodies and used by consumers. Pre-consumer materials include molded bodies that did not meet the quality standards of commercially available products that have already been coated or compounded. These post-consumer and pre-consumer materials can be crushed or pulverized as appropriate before use.

[0064] (Depolymerization) Depolymerization (decomposition) methods include hydrolysis using water, phenol-based phenolysis, alcohol-based alcohol-based alkolilysis, and amine-based aminolysis. A common depolymerization method involves decomposing the polycarbonate resin in a PC composite containing polycarbonate resin and other resins using decomposition agents such as water, phenol, alcohol, or amine in the presence of a solvent and catalyst. Any of these methods may be used for depolymerization.

[0065] Furthermore, it is preferable to prepare a slurry-like reaction solution in which a portion of the polycarbonate resin is dissolved in the solvent, and then proceed with depolymerization while dissolving the polycarbonate resin in the solvent. Even if the prepared reaction solution is in slurry form, the polycarbonate resin will dissolve as depolymerization progresses. In addition, depolymerization may proceed in parallel with the preparation of the reaction solution.

[0066] The temperature during depolymerization and the reaction temperature are not particularly limited and can be set appropriately according to the melting and boiling points of the raw materials and decomposition agents used. For example, the temperature can be 10 to 200°C or 20 to 180°C. The reaction time can be 0.1 to 30 hours, 0.5 to 25 hours, or 1 to 20 hours. Furthermore, depolymerization may be carried out at atmospheric pressure or under pressure.

[0067] (i) Method of depolymerization in the presence of aromatic monoalcohols From the perspective of ease of preparing the aromatic monoalcohol-containing solution, it is preferable to depolymerize the polycarbonate resin in the PC composite in the presence of the aromatic monoalcohol. Methods for depolymerizing in the presence of the aromatic monoalcohol include, for example, depolymerizing the polycarbonate resin in the presence of the aromatic monoalcohol and a catalyst, or depolymerizing the polycarbonate resin in the presence of the aromatic monoalcohol, a catalyst, and a decomposition agent other than the aromatic monoalcohol.

[0068] Aromatic monoalcohols can function as solvents or decomposition agents. Examples of aromatic monoalcohols include phenol, cresol, and xylenol, with phenol or cresol being preferred. In step 1, bisphenol such as bisphenol A can be precipitated as an adduct crystal, so phenol is more preferred as the aromatic monoalcohol.

[0069] The catalyst used during depolymerization should be one that can accelerate the decomposition of the polycarbonate resin. Examples of catalysts for depolymerization include alkali metal hydroxides such as sodium hydroxide and potassium hydroxide; alkali metal carbonates such as sodium carbonate, sodium bicarbonate, potassium carbonate, and potassium bicarbonate; alkylamines such as methylamine, ethylamine, propylamine, dimethylamine, diethylamine, and trimethylamine; inorganic acids such as hydrochloric acid, sulfuric acid, and phosphoric acid; and organic acids such as carboxylic acids and sulfonic acids.

[0070] A small mass ratio of catalyst to PC composite (mass of catalyst / mass of PC composite) tends to decrease the decomposition rate, leading to longer decomposition times and reduced efficiency. Therefore, the mass ratio is preferably 0.001 or higher, more preferably 0.005 or higher, and even more preferably 0.01 or higher. Furthermore, a large mass ratio tends to increase the amount of acid and base required for neutralization. Therefore, the mass ratio is preferably 50 or less, more preferably 20 or less, and even more preferably 10 or less.

[0071] Examples of decomposition agents other than aromatic monoalcohols include water, aliphatic monoalcohols, and amines. Examples of aliphatic monoalcohols include methanol, ethanol, n-propanol, i-propanol, n-butanol, i-butanol, t-butanol, n-pentanol, i-pentanol, n-hexanol, n-heptanol, n-octanol, n-nonanol, n-decanol, n-undecanol, and n-dodecanol. The aliphatic monoalcohol is preferably an alcohol having 1 to 5 carbon atoms, and is more preferably selected from the group consisting of methanol, ethanol, and butanol.

[0072] (ii) Method for depolymerization in the absence of aromatic monoalcohols Depolymerization may be carried out in the absence of aromatic monoalcohols. An example of a method for depolymerizing in the absence of aromatic monoalcohols is to depolymerize the polycarbonate resin in the PC composite in the presence of a solvent other than an aromatic monoalcohol, a catalyst, and a decomposition agent other than an aromatic monoalcohol.

[0073] Other than aromatic monoalcohols, there are no particular restrictions on solvents that dissolve polycarbonate resin, but examples include aromatic hydrocarbons such as benzene, toluene, and xylene; halogenated solvents such as methylene chloride; and dialkyl carbonates such as dimethyl carbonate, diethyl carbonate, dipropyl carbonate, and dibutyl carbonate. Furthermore, since aliphatic monoalcohols act as both a decomposition agent and a solvent, they can be supplied in excess of the amount used as a decomposition agent to function as both. Considering recycling, it is preferable to use a solvent with a boiling point of 200°C or lower.

[0074] A small mass ratio of solvent to PC composite (mass of solvent / mass of PC composite) tends to increase the time required for bisphenol production because a small ratio reduces the dissolution rate of the polycarbonate resin. Therefore, the mass ratio is preferably 0.01 or higher, more preferably 0.03 or higher, and even more preferably 0.05 or higher. Conversely, a large mass ratio increases the volume of solvent relative to the decomposition vessel, reducing the amount of polycarbonate resin that can be decomposed at one time and worsening the vessel efficiency. Therefore, the mass ratio is preferably 100 or less, more preferably 70 or less, and even more preferably 50 or less.

[0075] For catalysts and decomposition agents other than aromatic monoalcohols, (i) the same methods as those used in the depolymerization method in the presence of aromatic monoalcohols can be used.

[0076] One suitable method for depolymerization in the absence of aromatic monoalcohols is to use a dialkyl carbonate as a solvent and an aliphatic monoalcohol as a decomposition agent. The dialkyl carbonate and the aliphatic monoalcohol preferably have alkyl groups with the same number of carbon atoms, and more preferably have the same alkyl group with 1 to 5 carbon atoms. For example, a combination of dimethyl carbonate and methanol is preferred.

[0077] (mixed solution) In the method for producing bisphenol (I), the mixed solution is a decomposition solution obtained by depolymerizing the polycarbonate resin in a polycarbonate resin composite containing a polycarbonate resin and other resins.

[0078] (Bisphenol) The bisphenol contained in the decomposition solution is obtained by depolymerizing polycarbonate resin. Bisphenol has a structure corresponding to the bisphenol unit of polycarbonate resin. When a resin molded product containing polycarbonate resin having the constituent unit represented by formula (I) above is depolymerized, bisphenol represented by formula (II) below is obtained.

[0079] [ka]

[0080] R in general formula (II) 1 ~R 6 Regarding R in equation (I) above, 1 ~R 6 It is synonymous with [the above].

[0081] (Preparation of aromatic monoalcohol-containing solutions) The decomposition solution contains bisphenol produced by the depolymerization of the polycarbonate resin. The decomposition solution also contains other resins present in the PC composite, with at least some of these other resins dissolved in it. Furthermore, the decomposition solution contains the solvent and catalyst used in the depolymerization. Depending on the composition of the decomposition solution, it may be used directly in step 1, or an aromatic monoalcohol-containing solution may be prepared from the decomposition solution and used in step 1.

[0082] When depolymerization is carried out in the presence of an aromatic monoalcohol, the decomposition solution contains bisphenol, other resins contained in the PC composite, and the aromatic monoalcohol. In this case, when the decomposition solution contains an aromatic monoalcohol, it can be used as is as the aromatic monoalcohol-containing solution in step 1. Alternatively, the aromatic monoalcohol-containing solution may be diluted or concentrated to adjust the molar ratio of bisphenol to aromatic monoalcohol and the solubility of bisphenol. Dilution may be carried out using an aromatic monoalcohol or a solvent other than an aromatic monoalcohol. In other words, the mixed solution is obtained by carrying out depolymerization in the presence of an aromatic monoalcohol in the depolymerization step, and the mixed solution is the aromatic monoalcohol-containing solution. In this case, the aromatic monoalcohol used in the depolymerization step becomes the aromatic monoalcohol contained in the aromatic monoalcohol-containing solution.

[0083] When depolymerization is carried out in the absence of aromatic monoalcohols, the decomposition solution contains bisphenol, other resins contained in the PC complex, and solvents other than aromatic monoalcohols, but does not contain aromatic monoalcohols. In this case, if the decomposition solution does not contain aromatic monoalcohols, aromatic monoalcohols are added to prepare an aromatic monoalcohol-containing solution. For example, if the decomposition solution does not contain aromatic monoalcohols, an aromatic monoalcohol-containing solution can be prepared by solvent substitution. That is, the mixed solution is obtained by carrying out depolymerization in the presence of solvents other than aromatic monoalcohols in the depolymerization step, and the aromatic monoalcohol-containing solution is obtained by solvent substitution of the solvent in the obtained mixed solution with aromatic monoalcohols. Solvent substitution may involve substituting a portion of the solvent in the mixed solution or substituting all of it. Furthermore, dilution or concentration may be performed after solvent substitution to adjust the molar ratio of bisphenol to aromatic monoalcohols or the solubility of bisphenol. Dilution may be performed using aromatic monoalcohols or solvents other than aromatic monoalcohols.

[0084] To obtain a sufficient effect in suppressing the adhesion of other resins, the amount of aromatic monoalcohol is preferably 0.5 or more, more preferably 0.6 or more, even more preferably 0.7 or more, and particularly preferably 1.0 or more, relative to the amount of bisphenol in the aromatic monoalcohol-containing solution. If the amount of aromatic monoalcohol is too high, bisphenol will not precipitate easily, which will cause a decrease in yield. Therefore, the molar ratio of aromatic monoalcohol to bisphenol is preferably 20 or less, more preferably 15 or less, and even more preferably 10 or less. Accordingly, the amount of aromatic monoalcohol is preferably 0.5 to 20, more preferably 0.6 to 20, even more preferably 0.7 to 15, and particularly preferably 1.0 to 10, relative to the amount of bisphenol in the aromatic monoalcohol-containing solution.

[0085] The method for precipitating bisphenol in Step 1 and the method for solid-liquid separation, as well as the type of washing solution and washing conditions in Step 2, are as described above.

[0086] Furthermore, since the decomposition solution often contains insoluble matter, it is preferable to separate the mixed solution (decomposition solution) or the aromatic monoalcohol-containing solution into a homogeneous solution by solid-liquid separation before precipitating bisphenol. That is, it is preferable to use an aromatic monoalcohol-containing solution that is transparent to the naked eye in step 1. Solid-liquid separation can be performed by known means such as filtration or centrifugation. For example, solid-liquid separation can be performed using a horizontal belt filter, rotary vacuum filter, rotary pressure filter, centrifugal filter, centrifugal sedimentation separator, or a hybrid type of centrifuge (screen ball decanter) thereof. If other resins are insoluble matter, these other resins will be removed by this solid-liquid separation.

[0087] In the method for producing bisphenol (I), a specific example of using a homogeneous aromatic monoalcohol-containing solution is described below, which includes a depolymerization step, a solution preparation step, step 1A, and step 2. Depolymerization step: A step in which the polycarbonate resin in a polycarbonate resin composite containing polycarbonate resin and other resins is depolymerized to obtain a decomposition solution containing bisphenol and other resins. Solution preparation step: A step in which a homogeneous solution containing bisphenol, aromatic monoalcohols, and other resins is prepared using the decomposition solution obtained in the depolymerization step. Step 1A: A step in which bisphenol is precipitated from the homogeneous solution obtained in the solution preparation step to obtain a bisphenol slurry, and then the bisphenol slurry is subjected to solid-liquid separation to obtain a crude bisphenol cake and a mother liquor. Step 2: A washing solution is supplied to the crude bisphenol cake to wash the crude bisphenol cake and obtain the refined bisphenol cake.

[0088] This method involves preparing a homogeneous solution containing bisphenol, aromatic monoalcohol, and other resins besides polycarbonate resin from the decomposition solution obtained in the depolymerization step, and using this as the aromatic monoalcohol-containing solution in step 1. The depolymerization step and step 2 are the same as described above. Step 1A is the same as step 1 above, except that the homogeneous solution obtained in the solution preparation step is used as the aromatic monoalcohol-containing solution.

[0089] (Solution preparation process) The homogeneous solution of step 1A is prepared from the decomposition solution obtained in the depolymerization step. If the decomposition solution contains an aromatic monoalcohol, it may be used as is for the homogeneous solution of step 1A without concentration or dilution, or it may be concentrated or diluted as appropriate to prepare the homogeneous solution of step 1A. If the decomposition solution does not contain an aromatic monoalcohol, an aromatic monoalcohol may be added, and the solution may be concentrated as appropriate to prepare the homogeneous solution. In addition, when preparing the homogeneous solution, a solvent other than an aromatic monoalcohol may be added to adjust the solubility of bisphenol.

[0090] As described above, the amount of aromatic monoalcohol is preferably 0.5 to 20, more preferably 0.6 to 20, even more preferably 0.7 to 15, and particularly preferably 1.0 to 10 relative to the amount of bisphenol in the homogeneous solution. To ensure that the molar ratio of aromatic monoalcohol to bisphenol falls within this range, it is preferable to concentrate the decomposition solution containing bisphenol obtained in the depolymerization step or mix it with aromatic monoalcohol to prepare a homogeneous solution.

[0091] Furthermore, to remove impurities and obtain a homogeneous solution, the decomposition solution is subjected to solid-liquid separation. In the solution preparation step, it is preferable to filter the decomposition solution before using it in step 1A. The filtrate obtained by filtering the decomposition solution can be concentrated as appropriate before use. If the filtrate contains aromatic monoalcohols, the filtrate can be used in step 1A. If the filtrate does not contain aromatic monoalcohols, an organic solvent containing aromatic monoalcohols can be added to the filtrate to prepare a homogeneous solution, which can then be used in step 1A. Alternatively, if the decomposition solution does not contain aromatic monoalcohols, an organic solvent containing aromatic monoalcohols may be added to the decomposition solution, followed by filtration to prepare a homogeneous solution. If insoluble matter remains in the decomposition solution, it can be removed by filtration. If the PC composite contains other resins that are insoluble in aromatic monoalcohols, these resins can be removed by filtration. For example, polypropylene, polyethylene, polystyrene, etc., are insoluble in aromatic monoalcohols and can be removed by filtration.

[0092] (Bisphenol) The bisphenol contained in the homogeneous solution is obtained by depolymerizing a PC composite containing polycarbonate resin and other resins. The bisphenol has a structure corresponding to the bisphenol unit of the polycarbonate resin, and is the same as described above.

[0093] (Aromatic monoalcohols) Examples of aromatic monoalcohols included in the homogeneous solution include phenol, cresol, and xylenol, with phenol being preferred. When the depolymerization step is carried out in the presence of an aromatic monoalcohol, the aromatic monoalcohol used in the depolymerization step usually becomes the aromatic monoalcohol included in the homogeneous solution.

[0094] (Other resins) The other resins contained in the homogeneous solution are polymers with a molecular weight of 10,000 or more, and refer to high-molecular-weight compounds dissolved in the homogeneous solution. These other resins typically originate from the other resins contained in the PC composite used as a raw material for depolymerization. For example, when a resin molded product containing polycarbonate resin and other resins is depolymerized, the other resins constituting the resin molded product, and which dissolve in a solvent containing aromatic monoalcohols, become the other resins in the homogeneous solution. Specifically, examples of other resins contained in the homogeneous solution include at least one selected from the group consisting of acrylic resins, polyethylene terephthalate, polybutylene terephthalate, ABS resins, polyamides, phenolic resins, polyurethanes, polylactic acid, and silicone resins.

[0095] (Homogeneous solution) The homogeneous solution used in step 1 is a transparent solution containing bisphenol obtained by depolymerization and other resins derived from the PC composite. The homogeneous solution may also contain components other than bisphenol, aromatic monoalcohols, and other resins, such as catalysts, salts, and decomposition agents used during depolymerization.

[0096] Furthermore, some insoluble substances in the mixed solution (decomposition solution) or aromatic monoalcohol-containing solution may be difficult to identify visually. Therefore, regardless of whether the mixed solution (decomposition solution) or aromatic monoalcohol-containing solution is a homogeneous solution (visually transparent), it is preferable to filter (pass through a filter) or centrifuge the mixed solution (decomposition solution) or aromatic monoalcohol-containing solution (especially the aromatic monoalcohol-containing solution) before using it in step 1 or step 1A.

[0097] By precipitating bisphenol as adduct crystals, other resins are less likely to adhere to the precipitated crystals, improving the efficiency of removing other resins. Therefore, it is preferable to use phenol as the aromatic monoalcohol, precipitate adduct crystals consisting of bisphenol and phenol in step 1 or step 1A to obtain a crude cake of adduct crystals consisting of bisphenol and phenol, and then obtain a refined cake of adduct crystals consisting of bisphenol and phenol in step 2. More preferably, phenol is used as the aromatic monoalcohol, precipitate adduct crystals consisting of bisphenol A and phenol in step 1 or step 1A to obtain a crude cake of adduct crystals consisting of bisphenol and phenol, and then obtain a refined cake of adduct crystals consisting of bisphenol A and phenol in step 2.

[0098] <Method for producing bisphenol (II)> Figure 2 is a flow chart showing another example of the method for producing bisphenol according to the present invention. The method for producing bisphenol (II) shown in Figure 2 comprises a depolymerization step, step 1, step 2, an adsorption purification step, a water washing step, and a crystallization step.

[0099] The depolymerization step, step 1, and step 2 are the same as in the method for producing bisphenol (I).

[0100] [Adsorption purification process] In the method for producing bisphenol (II), the adsorption purification step is performed after step 2. This step involves dissolving or melting the purified cake in a solvent to obtain a bisphenol solution, and then contacting the bisphenol solution with a solid adsorbent to obtain an adsorption-purified solution. By purifying the bisphenol solution with a solid adsorbent in this way, impurities such as coloring components can be efficiently removed. Furthermore, since other resins are efficiently removed in steps 1 and 2, the filterability and permeability when in contact with the solid adsorbent are good.

[0101] (Bisphenol solution) In the method for producing bisphenol (II), the bisphenol solution is a solution obtained by dissolving or melting the refined cake in a solvent. The solvent in the bisphenol solution mainly consists of an organic solvent, but it may also contain water as long as it is within the range in which bisphenol can be dissolved. The organic solvent used in preparing the bisphenol solution can be any solvent that dissolves bisphenol, and can be aromatic hydrocarbons, aromatic monoalcohols, halogenated solvents, dialkyl carbonates, etc. In particular, it is preferable to include one or more selected from the group consisting of benzene, toluene, xylene, phenol, cresol, methylene chloride, dimethyl carbonate, and diethyl carbonate.

[0102] If the amount of organic solvent in the bisphenol solution is small, the viscosity of the solution will increase in proportion to the bisphenol concentration. If the viscosity is high, bisphenol may precipitate and adhere to the solid adsorbent during contact. In addition, when contacting the solid adsorbent using the percolation method described later, the differential pressure will be large, raising concerns about damage to the equipment. For this reason, it is preferable that the organic solvent content in the bisphenol solution be 20% by mass or more. The organic solvent content in the bisphenol solution can be arbitrarily adjusted to 30% by mass or more, 40% by mass or more, 50% by mass or more, etc., depending on the type of organic solvent.

[0103] Furthermore, if the refined cake is an adduct crystal composed of bisphenol and phenol, heating and melting the crystal can produce a bisphenol solution in which bisphenol is dissolved in phenol.

[0104] (Solid adsorbent) The solid adsorbent is preferably one with a large specific surface area that efficiently adsorbs coloring components, and preferably one that has pores that adsorb metal atoms such as sodium and potassium. Examples include activated clay, acid clay, activated carbon, and cation exchange resin. These solid adsorbents may be used individually or in combination of multiple types. The solid adsorbent preferably contains one selected from the group consisting of activated clay, acid clay, activated carbon, and cation exchange resin, and more preferably contains it as the main component (50% by mass or more in the solid adsorbent). Furthermore, for the purpose of improving filtration or assisting in dewatering, a mixture of one of the adsorbents selected from the group consisting of activated clay, acid clay, activated carbon, and cation exchange resin may be used with general adsorbents such as molecular sieves, silica gel, alumina, celite, and zeolite.

[0105] (Method of contact between bisphenol solution and solid adsorbent) There are no particular limitations on the method of bringing the bisphenol solution into contact with the solid adsorbent, but common methods include the contact method, in which the solid adsorbent is added to the bisphenol solution, thoroughly brought into contact with it while stirring, and then filtered off, and the percolation method, in which the bisphenol solution is passed through a column packed with the solid adsorbent.

[0106] In the contact method, if the amount of solid adsorbent supplied is too small, there is a risk that the coloring components will not be sufficiently adsorbed. Therefore, the amount of solid adsorbent supplied is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, and even more preferably 0.1% by mass or more, relative to the bisphenol being treated. On the other hand, if the amount of solid adsorbent supplied is too large, the coloring components can be sufficiently adsorbed, but there is a concern that the load on the filtration process will increase and economic efficiency will deteriorate. Therefore, the amount of solid adsorbent supplied is preferably 20% by mass or less, more preferably 10% by mass or less, and even more preferably 5% by mass or less, relative to the bisphenol dissolved in the bisphenol solution. Therefore, the amount of solid adsorbent supplied is preferably 0.01 to 20% by mass, more preferably 0.05 to 10% by mass, and even more preferably 0.1 to 5% by mass, relative to the bisphenol.

[0107] In the percolation method, the amount of solid adsorbent packed into the column should be in excess of the bisphenol being treated. If repeated use is intended, the amount can be 10 times, 100 times, 1000 times, or more than the amount of bisphenol being treated.

[0108] The adsorption purification process, which involves contacting a bisphenol solution with a solid adsorbent, is preferably carried out under an inert gas atmosphere. Contacting the bisphenol solution under an inert gas atmosphere, such as nitrogen or argon, helps maintain its color.

[0109] The temperature at which the bisphenol solution and the solid adsorbent come into contact is appropriately set depending on the type of solid adsorbent used. To more efficiently adsorb and remove coloring components, it is preferable that the bisphenol is completely dissolved in the bisphenol solution. Therefore, the temperature must take into account the solubility of bisphenol in the bisphenol solution. Accordingly, the temperature at which the bisphenol solution and the solid adsorbent come into contact is preferably 0°C to 200°C, more preferably 10°C to 190°C, and even more preferably 20°C to 180°C.

[0110] The contact time between the bisphenol solution and the solid adsorbent varies depending on the type and amount of solid adsorbent used and the temperature, but if it is too short, the adsorption of coloring components will be insufficient, so it is usually sufficient to allow at least 0.1 hours. If it is too long, the equipment will be occupied for a long time and the manufacturing efficiency will deteriorate, so it is usually within 100 hours. When the process is carried out by the percolation method, the processing time is controlled by the inner diameter and length of the column and the flow rate. The inner diameter and length of the column should preferably be large enough to accommodate the amount of bisphenol being processed, and specifically, the inner diameter should be about 10 mm to 1000 mm, the length 20 mm to 3000 mm, and the flow rate 1 to 1000 mL / min.

[0111] (Adsorbent purified solution) The adsorption-purified solution is the bisphenol solution after contact with a solid adsorbent. By treating it with a solid adsorbent, the adsorption-purified solution has reduced impurities compared to the bisphenol solution before treatment.

[0112] [Water washing process] The washing step involves mixing the adsorption-purified liquid obtained in the adsorption-purification step with water, separating it into an organic phase containing bisphenol and an aqueous phase, and then removing the aqueous phase to obtain the organic phase. Furthermore, if the electrical conductivity of the aqueous phase does not satisfy 10 μS / cm or less, the thermal stability of bisphenol may be impaired. Therefore, the washing step is repeated until the electrical conductivity of the removed aqueous phase becomes 10 μS / cm or less. Specifically, if the electrical conductivity of the removed aqueous phase exceeds 10 μS / cm, water is supplied again to the organic phase after the removal of the aqueous phase, causing phase separation between the organic phase and the aqueous phase, and the aqueous phase is removed. By repeating this operation, it is possible to reduce the electrical conductivity of the aqueous phase.

[0113] The supplied water can be distilled water, demineralized water, ion-exchanged water, or pure water. In order to efficiently wash the adsorption-purified solution, it is desirable that the electrical conductivity of the supplied water be as low as possible; for example, it is preferable to use water with an electrical conductivity of 5 μS / cm or less, or 2 μS / cm or less.

[0114] [Crystallization process] The crystallization step is a process of precipitating bisphenol from the organic phase obtained in the water washing step. The crystallization step can be carried out in the same manner as in step 1. Specifically, the organic phase is cooled to precipitate bisphenol, and the slurry liquid from which the bisphenol has precipitated is separated into bisphenol and crystallization mother liquor by solid-liquid separation to obtain bisphenol. This allows for the acquisition of solid bisphenol.

[0115] The obtained bisphenol may be dried as appropriate. There are no particular limitations on the drying method, but examples include heating under reduced pressure and distilling off the organic solvent. In the method for producing bisphenol (II), other resins are efficiently removed in steps 1 and 2, so the solvent can be sufficiently evaporated and the bisphenol can be dried.

[0116] Furthermore, if the organic phase obtained in the water washing step contains phenol, depending on the composition of the organic phase, bisphenols such as bisphenol A may precipitate as single crystals of bisphenol or as adduct crystals composed of bisphenol and phenol. Therefore, when producing bisphenol that forms adduct crystals with phenol, it is necessary to adjust the composition of the bisphenol solution used in the adsorption purification step and the organic phase after the water washing step, according to the crystal structure to be obtained in the crystallization step.

[0117] To obtain bisphenol as an adduct crystal, which forms adduct crystals with phenol, bisphenol should be precipitated in an organic phase containing at least 1.0 mole of phenol relative to the bisphenol. If the amount of phenol is too low, the slurry concentration will be high, which can cause problems such as scaling in the crystallizer. Therefore, the amount of phenol in the organic phase should preferably be 2.0 mole or more, and more preferably 3.0 mole or more, relative to the bisphenol.

[0118] For example, if the purified cake obtained in step 2 is an adduct crystal cake, the cake is melted or phenol is added to obtain a bisphenol solution. At this time, the molar ratio of phenol to bisphenol is adjusted to 1.0 mole or more. This solution is subjected to an adsorption purification step, followed by a water washing step. By cooling the obtained organic phase and precipitating crystals, adduct crystals can be obtained.

[0119] To obtain bisphenol as a single crystal, which forms adduct crystals with phenol, one should adjust the composition of the bisphenol solution in the adsorption purification step or the organic phase after the water washing step using an organic solvent other than phenol, so that when bisphenol precipitates, there is an excess of the organic solvent other than phenol compared to phenol. The molar ratio of the organic solvent other than phenol to phenol can be 5.0 moles or more, or 6.0 moles or more, etc.

[0120] If the refined cake obtained in step 2 is an adduct crystal cake, a bisphenol solution can be prepared by dissolving the refined cake in an aromatic hydrocarbon, for example, and single crystals of bisphenol can be obtained by performing an adsorption purification step, a water washing step, and a refinement crystallization step using this bisphenol solution. Alternatively, phenol may be removed by distillation before dissolving the refined cake in an aromatic hydrocarbon. In this case, it is preferable to remove the phenol by distillation until it is less than 1.0 mole relative to the bisphenol.

[0121] When an adsorption purification process is performed using a bisphenol solution such as a melted cake of adduct crystals, with a large amount of phenol present, single crystals of bisphenol can be obtained by, for example, adding aromatic hydrocarbons to the organic phase after the water washing process to adjust the composition of the organic phase, and then precipitating the bisphenol. Methods for adjusting the composition of the organic phase include distilling off phenol until the amount is less than 1.0 mole relative to the bisphenol in the organic phase, and then supplying aromatic hydrocarbons, or adjusting the phenol, water, and aromatic hydrocarbons to a constant composition. The amount of water relative to phenol is preferably 1.0 mole or more, and more preferably 1.2 moles or more. The amount of aromatic hydrocarbons relative to phenol is preferably 5.0 moles or more, and more preferably 6.0 moles or more. It is presumed that the presence of equimolar or more of water relative to phenol hydrates the phenol, suppressing the addition crystallization of bisphenol with phenol, and the presence of a large amount of aromatic hydrocarbons with low solubility for bisphenol promotes the precipitation of bisphenol crystals.

[0122] <Method for producing bisphenol (III)> Figure 3 is a flow chart showing another example of the method for producing bisphenol according to the present invention. The method for producing bisphenol (III) shown in Figure 3 comprises a depolymerization step, step 1, step 2, an adsorption purification step, a water washing step, a concentration step, and a granulation step.

[0123] The depolymerization step, step 1, step 2, adsorption purification step, and water washing step are the same as in the method for producing bisphenol (II).

[0124] [Concentration process] The concentration step involves removing the organic solvent from the organic phase obtained in the water washing step to obtain molten bisphenol. The concentration step is performed after repeatedly washing the aqueous phase with water until the electrical conductivity of the removed aqueous phase is 10 μS / cm or less.

[0125] In the concentration process, the organic solvent is removed by distillation of the organic phase to obtain bisphenol. Distillation may be carried out at atmospheric pressure, but reduced-pressure distillation is preferred. For example, reduced-pressure distillation is performed at a temperature of 150°C to 250°C and a pressure of 5kPa to 80kPa. The bisphenol obtained from the distillation apparatus is in a molten state and can be used directly in the next process.

[0126] [Granulation process] The granulation process is a process of obtaining granules by granulating molten bisphenol. By sending molten bisphenol (molten bisphenol) to a granulation column or flake and granulating it, solid bisphenol can be obtained as prills or flakes. For example, when molten bisphenol is supplied to a granulation column for granulation, the molten bisphenol is sent to the top of the granulation column and sprayed through numerous holes in a nozzle plate installed at the top of the column. The sprayed molten bisphenol is cooled by the circulating gas rising from the bottom of the granulation column and extracted from the bottom of the column as particulate solid called prills.

[0127] <Method for producing bisphenol (IV)> Furthermore, in the method for producing bisphenol according to the present invention, the bisphenol obtained by depolymerization can also be purified and recovered using an existing or newly constructed production plant that continuously synthesizes bisphenol from ketones or aldehydes and aromatic monoalcohols. An example of such a production method is shown in Figure 4.

[0128] The method for producing bisphenol shown in Figure 4 (IV) includes a bisphenol synthesis step to obtain bisphenol from a ketone or aldehyde and an aromatic monoalcohol, separate from the depolymerization step, step 1, step 2 and the adsorption purification step, and step X to supply the adsorption purified solution obtained in the adsorption purification step to the bisphenol synthesis step.

[0129] The depolymerization step, step 1, step 2, and adsorption purification step are the same as in the method for producing bisphenol (II).

[0130] [Bisphenol synthesis process] The bisphenol synthesis process involves obtaining bisphenol from a ketone or aldehyde and an aromatic monoalcohol, and includes steps A to D described below. Step A: A step in which a ketone or aldehyde and an aromatic monoalcohol are dehydrated and condensed in the presence of an acid catalyst to obtain a reaction solution A containing bisphenol. Step B: A step in which unreacted ketones or aldehydes and water are removed from reaction solution A by distillation to obtain concentrated solution B. Step C: A step in which the slurry obtained by crystallizing concentrated liquid B is separated into mother liquor C and cake c through solid-liquid separation. Step D: A step to purify cake c to obtain the bisphenol.

[0131] A manufacturing plant that continuously synthesizes bisphenol from ketones or aldehydes and aromatic monoalcohols may perform steps A to D described above, and a manufacturing plant that performs steps A to D can be used in the method for producing bisphenol. The bisphenol produced in the bisphenol synthesis step is the same as the bisphenol contained in the adsorption purification solution.

[0132] [Process X] Step X is the step of supplying the adsorption-purified solution to the bisphenol synthesis step. The adsorption-purified solution is supplied to one or more steps A to D of the bisphenol synthesis step. In this way, the bisphenol in the adsorption-purified solution can be purified and recovered together with the bisphenol produced from the ketone or aldehyde and the aromatic monoalcohol. The adsorption-purified solution may be supplied to one or more steps A to D of the bisphenol synthesis step. Preferably, the adsorption-purified solution is supplied to one or more steps A, B, and C.

[0133] Alternatively, the adsorption-purified solution may be distilled or crystallized to concentrate the bisphenol, and the resulting concentrate may be supplied to one or more steps in the bisphenol synthesis process. The concentrate may also be supplied to one or more steps in the bisphenol synthesis process after being replaced with a different solvent.

[0134] <Method for producing bisphenol (V)> Figure 5 is a flowchart illustrating the method for producing bisphenol shown in Figure 4 in more detail. Figure 5 shows a method for producing bisphenol A (BPA) by using waste material (BPA-type PC+p) of a resin molded product containing a polycarbonate resin (BPA-type PC) having bisphenol units derived from bisphenol A and another resin (p) that dissolves in phenol as raw materials for depolymerization, and carrying out the method for producing bisphenol (V) shown in Figure 4.

[0135] In the depolymerization step, waste plastics, such as resin molded products, are depolymerized in the presence of phenol to obtain a decomposition solution (BPA+PHL+p) containing bisphenol A, phenol, and other resins. At this time, water or aliphatic alcohols can be used as the decomposition agent, and it is preferable to use a basic catalyst. The decomposition solution (BPA+PHL+p) is usually obtained as a homogeneous solution by solid-liquid separation (e.g., filtration) and then used as the aromatic monoalcohol-containing solution in step 1.

[0136] In step 1, first, an aromatic monoalcohol-containing solution containing bisphenol A, phenol, and other resins is cooled to precipitate adduct crystals (BPA-PHL) composed of bisphenol A and phenol, obtaining a bisphenol A slurry. Next, the slurry containing the precipitated adduct crystals of bisphenol A and phenol is subjected to solid-liquid separation into a crude cake of bisphenol A and phenol adduct crystals (BPA-PHL) and a mother liquor to obtain a crude cake.

[0137] In step 2, the crude cake of the adduct crystal (BPA-PHL) consisting of bisphenol A and phenol is washed with heated water or aromatic hydrocarbons to obtain a refined cake.

[0138] In the adsorption purification process, first, the purified cake obtained in step 2 is dissolved or melted in phenol to obtain a solution in which bisphenol A is dissolved in phenol. Next, the obtained solution is purified by contacting it with a solid adsorbent to obtain an adsorption purified solution containing bisphenol A (PHL solution of BPA).

[0139] Furthermore, in step X, an adsorption purification solution containing bisphenol A is supplied to a BPA manufacturing plant that continuously produces bisphenol A from phenol and acetone. As a result, the bisphenol A in the adsorption purification solution is purified and recovered together with the bisphenol A produced by the condensation reaction of acetone and phenol at the BPA manufacturing plant.

[0140] The BPA manufacturing plant to which the adsorption purification solution is supplied carries out the following processes, including steps A1 to G1. Step A1: A step in which acetone and phenol are dehydrated and condensed in the presence of an acid catalyst to obtain reaction solution A1 containing bisphenol A. Step B1: A step in which unreacted acetone and water are removed from reaction solution A1 by distillation to obtain concentrated solution B1. Step C1: A step in which the slurry obtained by crystallizing the concentrated liquid B1 is subjected to solid-liquid separation to separate it into mother liquor C1 and cake c1. Step D1: A step to purify cake c1 to obtain bisphenol A. Process E1: A process in which a portion of the mother liquor C1 is circulated and supplied to process A1. Step F1: A step in which bisphenol A in mother liquor C1 is decomposed into phenol and isopropenylphenol under alkaline conditions, and then bisphenol A is produced by recombining the phenol and isopropenylphenol, thereby obtaining a solution F1 containing bisphenol A. Step G1: A step of supplying the solution F1 to step A1.

[0141] In particular, it is preferable to supply the adsorption purification solution containing bisphenol A to one or more steps selected from the group consisting of steps A1, B1, C1, E1, F1, and G1.

[0142] Furthermore, in the method for producing bisphenol of the present invention, step 2 may be omitted in steps (II) to (V), and the crude cake obtained in step 1 may be used in the adsorption purification step.

[0143] [Manufacturing method for recycled polycarbonate resin] The present invention relates to a method for producing recycled polycarbonate resin (hereinafter sometimes referred to as "the method for producing recycled polycarbonate resin of the present invention"), comprising the steps of obtaining bisphenol using the method for producing bisphenol of the present invention, and producing recycled polycarbonate resin using a bisphenol raw material containing the obtained bisphenol.

[0144] The recycled polycarbonate resin obtained by the method for producing recycled polycarbonate resin of the present invention can be produced by, for example, a transesterification reaction of a bisphenol raw material containing bisphenol (recycled bisphenol) obtained from the method for producing bisphenol of the present invention and a carbonate diester raw material such as diphenyl carbonate in the presence of an alkali metal compound and / or an alkaline earth metal compound. The bisphenol raw material may be recycled bisphenol alone, or recycled bisphenol may be used in combination with bisphenol obtained by a method other than the method for producing bisphenol of the present invention.

[0145] The above transesterification reaction can be carried out by appropriately selecting known methods, but an example using bisphenol A and diphenyl carbonate as starting materials is described below.

[0146] In the method for producing recycled polycarbonate resin of the present invention, it is preferable to use diphenyl carbonate in excess of bisphenol A. The amount of diphenyl carbonate used relative to bisphenol A is preferably high in terms of having fewer terminal hydroxyl groups in the produced recycled polycarbonate resin and having excellent thermal stability of the polymer, and preferably low in terms of having a fast transesterification reaction rate and facilitating the production of recycled polycarbonate resin with a desired molecular weight. For these reasons, the amount of diphenyl carbonate used per 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.

[0147] As for the method of supplying the raw materials, bisphenol A and diphenyl carbonate can be supplied in solid form, but it is preferable to supply one or both of them in a melted liquid state.

[0148] When producing recycled polycarbonate resin by the transesterification reaction of diphenyl carbonate and bisphenol A, a transesterification catalyst is usually used. In the above method for producing recycled 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 individually, or two or more may be used in any combination and ratio. In practice, it is desirable to use an alkali metal compound.

[0149] The amount of catalyst used per mole of bisphenol A or diphenyl carbonate is typically 0.05 μmol or more, preferably 0.08 μmol or more, more preferably 0.10 μmol or more, and also typically 100 μmol or less, preferably 50 μmol or less, and more preferably 20 μmol or less. By using a catalyst within the above range, it is easy to obtain the polymerization activity necessary to produce recycled polycarbonate resin with a desired molecular weight, and it is easy to obtain recycled polycarbonate resin with excellent polymer hue, without excessive polymer branching, and with excellent fluidity during molding.

[0150] To produce recycled polycarbonate resin using the above method, it is preferable to continuously supply both of the above raw materials to a raw material mixing tank, and to continuously supply the resulting mixture and the transesterification catalyst to a polymerization tank.

[0151] In the production of recycled polycarbonate resin by the transesterification method, the two raw materials are typically supplied to a raw material mixing tank, uniformly stirred, and then supplied to a polymerization tank to which a catalyst is added, thereby producing a polymer. [Examples]

[0152] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples unless its essence is changed.

[0153] [Raw materials and reagents] The polycarbonate resin used is "NOVAREX® M7027BF" from Mitsubishi Chemical Engineering Plastics Corporation. • The compound product of polycarbonate resin and PET resin (PC / PET resin) used was "MB2105" from Mitsubishi Chemical Engineering Plastics Corporation. The compound product of polycarbonate resin and PBT resin (PC / PBT resin) used was "MB4309R" from Mitsubishi Chemical Engineering Plastics Corporation. • For the compound product of polycarbonate resin and ABS resin (PC / ABS resin), we used "MB2213R" from Mitsubishi Chemical Engineering Plastics Corporation. Polyethylene terephthalate (PET), polybutylene terephthalate (PBT), ABS resin (ABS), polyamide 66 (PA66), phenolic resin (PHL resin), acrylic resin (PMMA), thermoplastic polyurethane (TPU), and polylactic acid (PLA) were tested using test resin pellets from Standard Test Piece Co., Ltd. Phenol (PHL), dimethyl carbonate, methanol, sodium bicarbonate, potassium hydroxide, dilute sulfuric acid, toluene, dodecanethiol, acetonitrile, cesium carbonate, activated carbon (powder), and biphenyl were reagents from Fujifilm Wako Pure Chemical Industries, Ltd. • Bisphenol A and diphenyl carbonate were products of Mitsubishi Chemical Corporation.

[0154] [Polymer Analysis] Quantitative analysis using GPC ·Equipment: Agilent 1100 Plgel 5μm 500Å 300×7.5mmI.D ×2 Plgel 5μm 100Å 300×7.5mmI.D ×1 ·Analysis temperature: 40℃ • Eluent: Tetrahydrofuran ·Analysis time 30 minutes Peaks detected between 15.0 and 17.0 minutes were aggregated and quantified as polymers with a molecular weight of 10,000 or more (based on standard polystyrene).

[0155] [Analysis of Bisphenol A] • Equipment: Shimadzu Corporation "LC10A" Unison UK C18 3μm 250×4.6mmI.D ·Analysis temperature: 40℃ • Eluent composition: A 10% / B 90% Isocratic mode A liquid water Solution B: Acetonitrile ·Analysis time 30 minutes

[0156] [Analysis of Toluene] • Equipment: Shimadzu Corporation GC-2014 Agilent DB-1 0.530mm×30m 1.50μm ·Method: FID • Evaporation chamber temperature: 230℃ Detector temperature: 300℃ • During the first 0 to 5 minutes of analysis, the column temperature was maintained at 50°C. From 5 to 30 minutes of analysis, the column temperature was gradually increased to 280°C. From 30 to 40 minutes of analysis, the column temperature was maintained at 280°C. • Quantitative analysis: Internal standard method. Biphenyl was used as the internal standard.

[0157] [Measurement of electrical conductivity of the aqueous phase in the washing process] • Equipment: COND METER D-71, manufactured by Horiba, Ltd. The water supplied during the washing process was desalinated water with an electrical conductivity of 0.9 μS / cm.

[0158] [Viscosity average molecular weight] The viscosity-average molecular weight (Mv) of polycarbonate resin was calculated by dissolving the polycarbonate resin in methylene chloride (concentration 6.0 g / L), measuring the specific viscosity (ηsp) at 20°C using an Ubbelohde viscous tube, and then 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

[0159] [PelletYI] The YI (transparency of polycarbonate resin (PC)) of the pellets was evaluated by measuring the YI value (yellowness index value) in the reflected light of polycarbonate resin pellets in accordance with ASTM D1925. A Konica Minolta spectrophotometer "CM-5" was used, and the measurement conditions were a measurement diameter of 30 mm and SCE (Surface-to-Eye Convergence). The calibration glass for petri dish measurement, "CM-A212," was fitted into the measurement section, and the zero calibration box "CM-A124" was placed over it to perform zero calibration. Subsequently, white calibration was performed using the built-in white calibration plate. Next, measurements were taken using the white calibration plate "CM-A210," and it was confirmed 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 measured pellets in a cylindrical glass container with an inner diameter of 30 mm and a height of 50 mm, packed to a depth of approximately 40 mm. The process of removing the pellets from the glass container and measuring again was repeated twice, and the average of the three measured values ​​was used.

[0160] [Example 1] (Preparation of a homogeneous solution) In a device (Personal Organic Synthesis Apparatus PPV-5460, manufactured by Tokyo Rikakikai Co., Ltd.) equipped with a glass three-neck reaction vessel, an aluminum block constant temperature bath, and a magnetic stirrer, 30 g of bisphenol A, 85 g of phenol, 30 g of water, and 5 g of PET pellets were added and stirred at 85°C for 2 hours. After 2 hours, the mixture was filtered using a glass filter equipped with a vacuum pump, and 150.0 g of filtrate was obtained. This was designated as homogeneous solution A. Analysis of the polymer content in homogeneous solution A revealed that 3.3% by mass of components with a molecular weight of 10,000 or more was detected, and it was found that 5.0 g of PET (3.3% by mass × 150.0 g homogeneous solution ÷ 100 = 5.0 g) was dissolved in homogeneous solution A.

[0161] (Obtaining crude bisphenol cake (Step 1)) Homogeneous solution A was placed in a three-necked glass reaction vessel and cooled to an internal temperature of 20°C to precipitate bisphenol A crystals, obtaining a slurry. This slurry was subjected to solid-liquid separation using a glass filter equipped with a vacuum pump to obtain 45 g of crude bisphenol A cake A. Analysis of the polymer content in this crude cake A revealed that 2.0 mass% of components with a molecular weight of 10,000 or more were detected, and it was found that crude cake A contained 0.9 g of PET (2.0 mass% × 45 g crude cake ÷ 100 = 0.9 g). The PET removal rate by obtaining the crude cake was 82 mass% (100 - 0.9 g / 5.0 g × 100 = 82 mass%).

[0162] (Obtaining bisphenol extract (Step 2)) Crude cake A was placed in a 200 mL glass beaker, and 120 g of demineralized water heated to 60°C was added. The mixture was stirred with a glass rod to form a slurry. This slurry was subjected to solid-liquid separation using a glass filter equipped with a vacuum pump. The same procedure was repeated to obtain 34 g of refined bisphenol A cake A. The amount of polymer in this refined cake A was analyzed, and components with a molecular weight of 10,000 or more were below the detection limit of 0.1% by mass. The final PET removal rate was 99% by mass or higher.

[0163] [Example 2] (Preparation of a homogeneous solution) The same procedure as in Example 1 was followed, except that PET was replaced with PBT, to obtain 148.7 g of homogeneous solution B. Some PBT pellets were filtered out using a glass filter, and when the amount of polymer in homogeneous solution B was measured, 2.5% by mass of components with a molecular weight of 10,000 or more was detected, and it was found that 3.7 g of PBT (2.5% by mass × 148.7 g of homogeneous solution ÷ 100 = 3.7 g) was dissolved in homogeneous solution B.

[0164] (Obtaining crude bisphenol cake (Step 1)) Homogeneous solution B was placed in a three-necked glass reaction vessel and cooled to an internal temperature of 20°C to precipitate bisphenol A crystals and obtain a slurry. This slurry was subjected to solid-liquid separation using a glass filter equipped with a vacuum pump to obtain 43 g of crude bisphenol A cake B. Analysis of the polymer content in this crude cake B revealed that 1.4 mass% of components with a molecular weight of 10,000 or more were detected, and it was found that crude cake B contained 0.6 g of PBT (1.4 mass% × 43 g crude cake ÷ 100 = 0.6 g). The PBT removal rate by obtaining the crude cake was 84 mass% (100 - 0.6 g / 3.7 g × 100 = 84 mass%).

[0165] (Obtaining bisphenol extract (Step 2)) Crude cake B was placed in a 200 mL glass beaker, and 120 g of demineralized water heated to 60°C was added. The mixture was stirred with a glass rod to form a slurry. This slurry was subjected to solid-liquid separation using a glass filter equipped with a vacuum pump. The same procedure was repeated to obtain 30 g of refined bisphenol A cake B. The amount of polymer in this refined cake B was analyzed, and components with a molecular weight of 10,000 or more were below the detection limit of 0.1% by mass. The final PBT removal rate was 99% by mass or higher.

[0166] [Example 3] (Preparation of a homogeneous solution) The same procedure as in Example 1 was followed, except that PET was replaced with ABS resin, to obtain 149.0 g of homogeneous solution C. Some ABS resin pellets were filtered out using a glass filter. When the amount of polymer in homogeneous solution C was measured, 2.7% by mass of components with a molecular weight of 10,000 or more was detected, and it was found that 4.0 g of ABS resin (2.7% by mass × 149.0 g of homogeneous solution ÷ 100 = 4.0 g) was dissolved in homogeneous solution C.

[0167] (Obtaining crude bisphenol cake (Step 1)) A homogeneous solution C was placed in a three-necked glass reaction vessel and cooled to an internal temperature of 20°C to precipitate bisphenol A crystals, obtaining a slurry. This slurry was subjected to solid-liquid separation using a glass filter equipped with a vacuum pump to obtain 44 g of crude bisphenol A cake C. Analysis of the polymer content in this crude cake C revealed that 1.4% by mass of components with a molecular weight of 10,000 or more was detected, and it was found that crude cake C contained 0.6 g of ABS resin (1.4% by mass × 44 g crude cake ÷ 100 = 0.6 g). The removal rate of ABS resin by obtaining the crude cake was 85% by mass (100 - 0.6 g / 4.0 g × 100 = 85% by mass).

[0168] (Obtaining bisphenol extract (Step 2)) Crude cake C was placed in a 200 mL glass beaker, 120 g of demineralized water at room temperature was added, and the mixture was stirred with a glass rod to form a slurry. This slurry was subjected to solid-liquid separation using a glass filter equipped with a vacuum pump. The same procedure was repeated to obtain 31 g of refined bisphenol A cake C. The amount of polymer in this refined cake C was analyzed, and components with a molecular weight of 10,000 or more were below the detection limit of 0.1% by mass. The final removal rate of ABS resin was 99% by mass or higher.

[0169] [Example 4] (Preparation of a homogeneous solution) The same procedure as in Example 1 was followed, except that PET was replaced with PA66, to obtain 150.0 g of homogeneous solution D. Measurement of the polymer content in homogeneous solution D revealed that 3.3% by mass of components with a molecular weight of 10,000 or more was detected, indicating that 5.0 g of PA66 (3.3% by mass × 150.0 g homogeneous solution ÷ 100 = 5.0 g) was dissolved in homogeneous solution D.

[0170] (Obtaining crude bisphenol cake (Step 1)) Homogeneous solution D was placed in a three-necked glass reaction vessel and cooled to an internal temperature of 20°C to precipitate bisphenol A crystals and obtain a slurry. This slurry was subjected to solid-liquid separation using a glass filter equipped with a vacuum pump to obtain 44 g of crude bisphenol A cake D. Analysis of the polymer content in this crude cake D revealed that components with a molecular weight of 10,000 or more accounted for 1.4% by mass, and it was found that crude cake D contained 0.6 g of PA66 (1.4% by mass × 44 g crude cake ÷ 100 = 0.6 g). The removal rate of PA66 by obtaining the crude cake was 88% by mass (100 - 0.6 g / 5.0 g × 100 = 88% by mass).

[0171] (Obtaining bisphenol extract (Step 2)) Crude cake D was placed in a 200 mL glass beaker, 120 g of toluene heated to 60°C was added, and the mixture was stirred with a glass rod to form a slurry. This slurry was subjected to solid-liquid separation using a glass filter equipped with a vacuum pump. The same procedure was repeated to obtain 30 g of refined bisphenol A cake D. The amount of polymer in this refined cake D was analyzed, and components with a molecular weight of 10,000 or more were below the detection limit of 0.1% by mass. The final removal rate of PA66 was 99% by mass or higher.

[0172] [Example 5] (Preparation of a homogeneous solution) The same procedure as in Example 1 was followed, except that PET was replaced with PMMA, to obtain 149.9 g of homogeneous solution E. Measurement of the polymer content in homogeneous solution E revealed that 3.3% by mass of components with a molecular weight of 10,000 or more was detected, indicating that 4.9 g of PMMA (3.3% by mass × 149.0 g of homogeneous solution ÷ 100 = 4.9 g) was dissolved in homogeneous solution E.

[0173] (Obtaining crude bisphenol cake (Step 1)) A homogeneous solution E was placed in a three-necked glass reaction vessel and cooled to an internal temperature of 20°C to precipitate bisphenol A crystals, obtaining a slurry. This slurry was subjected to solid-liquid separation using a glass filter equipped with a vacuum pump to obtain 45 g of crude bisphenol A cake E. Analysis of the polymer content in this crude cake E revealed that 2.2% by mass of components with a molecular weight of 10,000 or more was detected, and it was found that crude cake E contained 1.0 g of PMMA (2.2% by mass × 45 g crude cake ÷ 100 = 1.0 g). The PMMA removal rate by obtaining the crude cake was 80% by mass (100 - 1.0 g / 4.9 g × 100 = 80% by mass).

[0174] (Obtaining bisphenol extract (Step 2)) Crude cake E was placed in a 200 mL glass beaker, and 120 g of toluene heated to 60°C was added. The mixture was stirred with a glass rod to form a slurry. This slurry was subjected to solid-liquid separation using a glass filter equipped with a vacuum pump. The same procedure was repeated to obtain 30 g of refined bisphenol A cake E. The amount of polymer in this refined cake E was analyzed, and components with a molecular weight of 10,000 or more were below the detection limit of 0.1% by mass. The final PMMA removal rate was 99% by mass or higher.

[0175] [Example 6] (Preparation of a homogeneous solution) The same procedure as in Example 1 was followed, except that PET was replaced with TPU, to obtain 148.9 g of homogeneous solution F. Some of the TPU pellets were filtered out using a glass filter. When the amount of polymer in homogeneous solution F was measured, 2.6% by mass of components with a molecular weight of 10,000 or more was detected, and it was found that 3.9 g of TPU (2.6% by mass × 148.9 g of homogeneous solution ÷ 100 = 3.9 g) was dissolved in homogeneous solution F.

[0176] (Obtaining crude bisphenol cake (Step 1)) A homogeneous solution F was placed in a three-necked glass reaction vessel and cooled to an internal temperature of 20°C to precipitate bisphenol A crystals, obtaining a slurry. This slurry was subjected to solid-liquid separation using a glass filter equipped with a vacuum pump to obtain 43 g of crude bisphenol A cake F. Analysis of the polymer content in this crude cake F revealed that 1.5% by mass of components with a molecular weight of 10,000 or more was detected, and it was found that the crude cake F contained 0.6 g of TPU (1.5% by mass × 43 g crude cake ÷ 100 = 0.6 g). The removal rate of TPU by obtaining the crude cake was 85% by mass (100 - 0.6 g / 3.9 g × 100 = 85% by mass).

[0177] (Obtaining bisphenol extract (Step 2)) Crude cake F was placed in a 200 mL glass beaker, and 120 g of demineralized water heated to 60°C was added. The mixture was stirred with a glass rod to form a slurry. This slurry was subjected to solid-liquid separation using a glass filter equipped with a vacuum pump. The same procedure was repeated to obtain 32 g of refined bisphenol A cake F. The amount of polymer in this refined cake F was analyzed, and components with a molecular weight of 10,000 or more were below the detection limit of 0.1% by mass. The final removal rate of TPU was 99% by mass or higher.

[0178] [Example 7] (Preparation of a homogeneous solution) The same procedure as in Example 1 was followed, except that PET was replaced with PLA, to obtain 148.8 g of homogeneous solution G. Some PLA pellets were filtered out using a glass filter, and when the amount of polymer in homogeneous solution G was measured, 2.5% by mass of components with a molecular weight of 10,000 or more was detected, and it was found that 3.7 g of PLA (2.5% by mass × 148.8 g of homogeneous solution ÷ 100 = 3.7 g) was dissolved in homogeneous solution G.

[0179] (Obtaining crude bisphenol cake (Step 1)) A homogeneous solution G was placed in a three-necked glass reaction vessel and cooled to an internal temperature of 20°C to precipitate bisphenol A crystals, obtaining a slurry. This slurry was subjected to solid-liquid separation using a glass filter equipped with a vacuum pump to obtain 42 g of crude bisphenol A cake G. Analysis of the polymer content in this crude cake G revealed that 1.1% by mass of components with a molecular weight of 10,000 or more was detected, indicating that the crude cake G contained 0.5 g of PLA (1.1% by mass × 42 g crude cake ÷ 100 = 0.5 g). The PLA removal rate by obtaining the crude cake was 86% by mass (100 - 0.5 g / 3.7 g × 100 = 86% by mass).

[0180] (Obtaining bisphenol extract (Step 2)) Crude cake G was placed in a 200 mL glass beaker, 120 g of toluene at room temperature was added, and the mixture was stirred with a glass rod to form a slurry. This slurry was subjected to solid-liquid separation using a glass filter equipped with a vacuum pump. The same procedure was repeated to obtain 31 g of refined bisphenol A cake G. The amount of polymer in this refined cake G was analyzed, and components with a molecular weight of 10,000 or more were below the detection limit of 0.1% by mass. The final PLA removal rate was 99% by mass or higher.

[0181] [Example 8] (Preparation of a homogeneous solution) The same procedure as in Example 1 was followed, except that PET was replaced with phenolic resin (PHL resin), to obtain 150.0 g of homogeneous solution H. Measurement of the polymer content in homogeneous solution H revealed that 3.3% by mass of components with a molecular weight of 10,000 or more was detected, indicating that 5.0 g of phenolic resin (3.3% by mass × 150.0 g homogeneous solution ÷ 100 = 5.0 g) was dissolved in homogeneous solution H.

[0182] (Obtaining crude bisphenol cake (Step 1)) A homogeneous solution H was placed in a three-necked glass reaction vessel and cooled to an internal temperature of 20°C to precipitate bisphenol A crystals, obtaining a slurry. This slurry was subjected to solid-liquid separation using a glass filter equipped with a vacuum pump to obtain 42 g of crude bisphenol A cake H. Analysis of the polymer content in this crude cake H revealed that 1.3% by mass of components with a molecular weight of 10,000 or more was detected, indicating that the crude cake H contained 0.5 g of phenolic resin (1.3% by mass × 42 g crude cake ÷ 100 = 0.5 g). The removal rate of phenolic resin by obtaining the crude cake was 90% by mass (100 - 0.5 g / 5.0 g × 100 = 90% by mass).

[0183] (Obtaining bisphenol extract (Step 2)) Crude cake H was placed in a 200 mL glass beaker, and 120 g of demineralized water heated to 60°C was added. The mixture was stirred with a glass rod to form a slurry. This slurry was subjected to solid-liquid separation using a glass filter equipped with a vacuum pump. The same procedure was repeated to obtain 30 g of refined bisphenol A cake H. The amount of polymer in this refined cake H was analyzed, and components with a molecular weight of 10,000 or more were below the detection limit of 0.1% by mass. The final removal rate of phenolic resin was 99% by mass or higher.

[0184] [Comparative Example 1] (Preparation of a homogeneous solution) In a device (Personal Organic Synthesis Apparatus PPV-5460, manufactured by Tokyo Rikakikai Co., Ltd.) equipped with a glass three-neck reaction vessel, an aluminum block constant temperature bath, and a magnetic stirrer, 50 g of bisphenol A, 40 g of dimethyl carbonate, and 10 g of ABS resin pellets were placed and stirred at 85°C for 2 hours. After 2 hours, the mixture was filtered using a glass filter equipped with a vacuum pump, and 98.6 g of filtrate was obtained. This was designated as homogeneous solution I. Analysis of the polymer content in homogeneous solution I revealed that 8.6% by mass of components with a molecular weight of 10,000 or more was detected, and it was found that 8.5 g of ABS resin (8.6% by mass × 98.6 g of homogeneous solution ÷ 100 = 8.5 g) was dissolved in homogeneous solution I.

[0185] (Obtaining crude bisphenol cake) Homogeneous solution I was placed in a three-necked glass reaction vessel and cooled to an internal temperature of 50°C. After confirming that it had cooled to 50°C, 80g of toluene was added, and it was further cooled to 20°C to precipitate bisphenol A crystals and obtain a slurry. This slurry was subjected to solid-liquid separation using a glass filter equipped with a vacuum pump to obtain 46g of crude bisphenol A cake I. Analysis of the polymer content in this crude cake I revealed that components with a molecular weight of 10,000 or more accounted for 15.9% by mass, and it was found that crude cake I contained 7.3g of ABS resin (15.9% by mass × 46g crude cake ÷ 100 = 7.3g). The removal rate of ABS resin by obtaining the crude cake was 14% by mass (100 - 7.3g / 8.5g × 100 = 14% by mass).

[0186] (Obtaining bisphenol extract) Crude cake I was placed in a 200 mL glass beaker, and 150 g of toluene heated to 60°C was added. The mixture was stirred with a glass rod to form a slurry. This slurry was subjected to solid-liquid separation using a glass filter equipped with a vacuum pump. The same procedure was repeated to obtain 44 g of refined bisphenol A cake I. Analysis of the polymer content in this refined cake I revealed that 15.5% by mass of components with a molecular weight of 10,000 or more was detected, and it was found that refined cake I contained 6.8 g of ABS resin (15.5% by mass × 44 g refined cake ÷ 100 = 6.8 g). The final removal rate of ABS resin was 20% by mass (100 - 6.8 g / 8.5 g × 100 = 20% by mass).

[0187] [Comparative Example 2] (Preparation of a homogeneous solution) The same procedure as in Comparative Example 1 was followed, except that ABS resin was replaced with PMMA, to obtain 100.0 g of homogeneous solution J. Analysis of the polymer content in homogeneous solution J revealed that 10.0% by mass of components with a molecular weight of 10,000 or more was detected, indicating that 10.0 g of PMMA (10.0% by mass × 100.0 g homogeneous solution ÷ 100 = 10.0 g) was dissolved in homogeneous solution J.

[0188] (Obtaining crude bisphenol cake) A homogeneous solution J was placed in a three-necked glass reaction vessel and cooled to an internal temperature of 50°C. After confirming that it had cooled to 50°C, 80g of toluene was added, and it was further cooled to 20°C to precipitate bisphenol A crystals and obtain a slurry. This slurry was subjected to solid-liquid separation using a glass filter equipped with a vacuum pump to obtain 50g of crude bisphenol A cake J. Analysis of the polymer content in this crude cake J revealed that components with a molecular weight of 10,000 or more accounted for 19.7% by mass, and it was found that the crude cake J contained 9.9g of PMMA (19.7% by mass × 50g crude cake ÷ 100 = 9.9g). The PMMA removal rate by obtaining the crude cake was 1% by mass (100 - 9.9g / 10.0g × 100 = 1% by mass).

[0189] (Obtaining bisphenol extract) Crude cake J was placed in a 200 mL glass beaker, 150 g of toluene heated to 60°C was added, and the mixture was stirred with a glass rod to form a slurry. This slurry was subjected to solid-liquid separation using a glass filter equipped with a vacuum pump. The same procedure was repeated to obtain 45 g of refined bisphenol A cake J. Analysis of the polymer content in this refined cake J revealed that components with a molecular weight of 10,000 or more accounted for 21.0% by mass, and it was found that the refined cake J contained 9.5 g of PMMA (21.0% by mass × 45 g of refined cake ÷ 100 = 9.5 g). The final PMMA removal rate was 5% by mass (100 - 9.5 g / 10.0 g × 100 = 5% by mass).

[0190] [Comparative Example 3] (Preparation of a homogeneous solution) The same procedure as in Comparative Example 1 was followed, except that ABS resin was replaced with PLA, to obtain 99.6 g of homogeneous solution K. Analysis of the polymer content in homogeneous solution K revealed that 9.6% by mass of components with a molecular weight of 10,000 or more was detected, indicating that 9.6 g of PLA (9.6% by mass × 99.6 g of homogeneous solution ÷ 100 = 9.6 g) was dissolved in homogeneous solution K.

[0191] (Obtaining crude bisphenol cake) Homogeneous solution K was placed in a three-necked glass reaction vessel and cooled to an internal temperature of 50°C. After confirming that it had cooled to 50°C, 80g of toluene was added, and it was further cooled to 20°C to precipitate bisphenol A crystals and obtain a slurry. This slurry was subjected to solid-liquid separation using a glass filter equipped with a vacuum pump to obtain 48g of crude bisphenol A cake K. Analysis of the polymer content in this crude cake K revealed that 15.3% by mass of components with a molecular weight of 10,000 or more was detected, and it was found that crude cake K contained 7.3g of PLA (15.3% by mass × 48g crude cake ÷ 100 = 7.3g). The PLA removal rate by obtaining the crude cake was 24% by mass (100 - 7.3g / 9.6g × 100 = 24% by mass).

[0192] (Obtaining bisphenol extract) Crude cake K was placed in a 200 mL glass beaker, 150 g of toluene heated to 60°C was added, and the mixture was stirred with a glass rod to form a slurry. This slurry was subjected to solid-liquid separation using a glass filter equipped with a vacuum pump. The same procedure was repeated to obtain 43 g of refined bisphenol A cake K. Analysis of the polymer content in this refined cake K revealed that 15.7 mass% of components with a molecular weight of 10,000 or more were detected, and it was found that the refined cake K contained 6.8 g of PLA (15.7 mass% × 43 g refined cake ÷ 100 = 6.8 g). The final PLA removal rate was 29 mass% (100 - 6.8 g / 9.6 g × 100 = 29 mass%).

[0193] [Comparative Example 4] (Preparation of a homogeneous solution) The same procedure as in Comparative Example 1 was followed, except that ABS resin was replaced with phenolic resin, to obtain 99.8 g of homogeneous solution L. Analysis of the polymer content in homogeneous solution L revealed that 9.8% by mass of components with a molecular weight of 10,000 or more was detected, indicating that 9.8 g of phenolic resin (9.8% by mass × 99.8 g of homogeneous solution ÷ 100 = 9.8 g) was dissolved in homogeneous solution L.

[0194] (Obtaining crude bisphenol cake) A homogeneous solution L was placed in a three-necked glass reaction vessel and cooled to an internal temperature of 50°C. After confirming that it had cooled to 50°C, 80g of toluene was added, and it was further cooled to 20°C to precipitate bisphenol A crystals and obtain a slurry. This slurry was subjected to solid-liquid separation using a glass filter equipped with a vacuum pump to obtain 49g of crude bisphenol A cake L. Analysis of the polymer content in this crude cake L revealed that 17.9% by mass of components with a molecular weight of 10,000 or more was detected, and it was found that the crude cake L contained 8.8g of phenol resin (17.9% by mass × 49g crude cake ÷ 100 = 8.8g). The removal rate of phenol resin by obtaining the crude cake was 10% by mass (100 - 8.8g / 9.8g × 100 = 10% by mass).

[0195] (Obtaining bisphenol extract) Crude cake L was placed in a 200 mL glass beaker, 150 g of toluene heated to 60°C was added, and the mixture was stirred with a glass rod to form a slurry. This slurry was subjected to solid-liquid separation using a glass filter equipped with a vacuum pump. The same procedure was repeated to obtain 45 g of refined bisphenol A cake L. Analysis of the polymer content in this refined cake L revealed that 16.9% by mass of components with a molecular weight of 10,000 or more was detected, and it was found that the refined cake L contained 7.6 g of phenolic resin (16.9% by mass × 45 g refined cake ÷ 100 = 7.6 g). The final removal rate of phenolic resin was 22% by mass (100 - 7.6 g / 9.8 g × 100 = 22% by mass).

[0196] [Comparative Example 5] (Preparation of a homogeneous solution) The same procedure as in Comparative Example 1 was performed, except that ABS resin was replaced with PMMA and dimethyl carbonate was replaced with methylene chloride, to obtain 100.0 g of homogeneous solution M. Analysis of the polymer content in homogeneous solution M revealed that 10.0% by mass of components with a molecular weight of 10,000 or more was detected, indicating that 10.0 g of PMMA (10.0% by mass × 100.0 g homogeneous solution ÷ 100 = 10.0 g) was dissolved in homogeneous solution M.

[0197] (Obtaining crude bisphenol cake) A homogeneous solution M was placed in a three-necked glass reaction vessel and cooled to an internal temperature of 50°C. After confirming that it had cooled to 50°C, 90g of toluene was added, and it was further cooled to 20°C to precipitate bisphenol A crystals and obtain a slurry. This slurry was subjected to solid-liquid separation using a glass filter equipped with a vacuum pump to obtain 47g of crude bisphenol A cake M. Analysis of the polymer content in this crude cake M revealed that components with a molecular weight of 10,000 or more accounted for 20.1% by mass, and it was found that the crude cake M contained 9.4g of PMMA (20.1% by mass × 47g crude cake ÷ 100 = 9.4g). The PMMA removal rate by obtaining the crude cake was 6% by mass (100 - 9.4g / 10.0g × 100 = 6% by mass).

[0198] (Obtaining bisphenol extract) Crude cake M was placed in a 200 mL glass beaker, 150 g of toluene heated to 60°C was added, and the mixture was stirred with a glass rod to form a slurry. This slurry was subjected to solid-liquid separation using a glass filter equipped with a vacuum pump. The same procedure was repeated to obtain 42 g of refined bisphenol A cake M. Analysis of the polymer content in this refined cake M revealed that 20.8 mass% of components with a molecular weight of 10,000 or more were detected, and it was found that the refined cake M contained 8.7 g of PMMA (20.8 mass% × 42 g refined cake ÷ 100 = 8.7 g). The final PMMA removal rate was 13 mass% (100 - 8.7 g / 10.0 g × 100 = 13 mass%).

[0199] The results for Examples 1-8 and Comparative Examples 1-5 are summarized in Table 1.

[0200] [Table 1]

[0201] [Example 9] (Depolymerization process) In a jacketed separable flask equipped with a Liebig condenser, stirring blades, and a thermometer, 120 g of polycarbonate resin (since the repeating units of polycarbonate resin are 254 g / mol, 120 g ÷ 254 g / mol = 0.472 moles), 107 g of sodium bicarbonate aqueous solution adjusted to 7% by mass, 360 g of phenol, 2.4 g of dodecanethiol, and 12 g of PMMA pellets were placed at room temperature under a nitrogen atmosphere. The reaction solution was in the form of a slurry. Subsequently, the internal temperature was raised to 90°C, and the reaction was allowed to proceed for 4 hours while maintaining this temperature to obtain a decomposition solution (homogeneous solution). A portion of this decomposition solution was analyzed for composition using high-performance liquid chromatography to confirm the formation of bisphenol A. This decomposition solution was filtered using a glass filter equipped with a vacuum pump, and 580 g of the resulting filtrate was prepared as homogeneous solution N. A portion of this homogeneous solution N was analyzed for composition using GPC, and 2.0 mass% of components with a molecular weight of 10,000 or more were detected. It was found that homogeneous solution N contained 11.6 g of PMMA (2.0 mass% × 580 g of homogeneous solution N ÷ 100 = 11.6 g).

[0202] (Process 1) The obtained homogeneous solution N was gradually cooled from 90°C to 10°C to obtain a slurry. The obtained slurry was filtered to obtain 206 g of crude cake N (solid component) and 355 g of crude crystallization mother liquor. Analysis of the polymer content in this crude cake M revealed that 1.4 mass% of components with a molecular weight of 10,000 or more were detected, and it was found that crude cake N contained 2.9 g of PMMA (1.4 mass% × crude cake 206 g ÷ 100 = 2.9 g). The PMMA removal rate by obtaining the crude cake was 75 mass% (100 - 2.9 g / 11.6 g × 100 = 75 mass%).

[0203] (Process 2) 450g of desalted water heated to 60°C was sprinkled onto the crude cake N to wash it, and 136g of refined cake N was obtained. The amount of polymer in this refined cake N was analyzed, and components with a molecular weight of 10,000 or more were below the detection limit (0.1% by mass or less). The removal rate of PMMA was 99% by mass or more. Furthermore, a compositional analysis of a portion of the crude cake after washing by high-performance liquid chromatography confirmed that it was an adduct crystal in which phenol was added to bisphenol A.

[0204] (Adsorption purification process) The obtained purified cake N was returned to a jacketed separable flask equipped with a Liebig condenser, stirring blades, and a thermometer. 600 g of toluene was added, and the mixture was heated to 75°C to dissolve it, obtaining organic phase N1 (bisphenol solution) containing bisphenol A. This organic phase N1 was gradually supplied to a glass filter lined with 20g of activated carbon, and suction filtration was performed to obtain organic phase N2 (adsorbed purified liquid). The filtration performance was good.

[0205] (Water washing process) The obtained organic phase N2 was returned to the separable flask, 100g of water was added, and the mixture was stirred for 15 minutes while maintaining the temperature at 75°C. After standing for 10 minutes, the two phases were separated to obtain the organic phase and the aqueous phase. This procedure was repeated three times to obtain the organic phase N3. The aqueous phase from the fourth extraction was transferred to a heat-resistant bottle, cooled to 25°C, and its electrical conductivity was measured to be 2.2 μS / cm.

[0206] (Precipitation crystallization process) Thereafter, the organic phase N3 was cooled to 10 °C to obtain a slurry. The obtained slurry was filtered to obtain 75 g of a cake. The obtained cake was dried by holding at 85 °C for 5 hours using a rotary evaporator to obtain 60 g of bisphenol A. The yield was 56 mol% (60 g ÷ 228 g / mol ÷ 0.472 × 100 = 56 mol%). When the obtained bisphenol A was analyzed using gas chromatography, the toluene content (TOL content) was 500 ppm by mass.

[0207] [Example 10] (Depolymerization process) Under a nitrogen atmosphere, 125 g of methanol, 300 g of dimethyl carbonate, and 3 g of potassium hydroxide were placed in a jacketed separable flask equipped with a Dimroth condenser, a stirring blade, and a thermometer. Then, 200 g of a polycarbonate resin (since the molecular weight of the repeating unit derived from bisphenol of the polycarbonate resin is 254 g / mol, the number of moles of the repeating unit derived from bisphenol = 200 g ÷ 254 g / mol = 0.787 mol) and 20 g of PMMA pellets were added at room temperature. Thereafter, the jacket temperature was raised to 80 °C. Undissolved polycarbonate resin was observed in the reaction solution when it reached 80 °C, and it was in a slurry state. Also, methanol was refluxing. The reaction was carried out for 3 hours while maintaining the jacket temperature at 80 °C to obtain a decomposition solution (homogeneous solution). A part of this decomposition solution was analyzed for its composition by high performance liquid chromatography, and it was confirmed that it contained 24.3 mass% of bisphenol A, 153 g (24.3 mass% × 628 g of the decomposition solution ÷ 100 = 153 g).

[0208] To the obtained decomposition solution, dilute sulfuric acid was added until the aqueous phase reached pH 6, and then filtration was performed using a glass filter equipped with a vacuum pump to obtain 645 g of a homogeneous solution. A part of this homogeneous solution was subjected to composition analysis by GPC, and it was found that components with a molecular weight of 10,000 or more were detected at 3.0% by mass, and 19.4 g (3.0% by mass × 645 g of homogeneous solution ÷ 100 = 19.4 g) of PMMA was contained in the homogeneous solution.

[0209] The homogeneous solution was transferred to a distillation apparatus equipped with a thermometer, a stirring blade, a distillation tube, and a pressure regulator. After adding 60 g of phenol, the pressure was changed from normal pressure (760 Torr) to 120 Torr, and while observing the distillate amount, the internal temperature was raised from room temperature to 80 °C, and 410 g was withdrawn as a fraction to obtain a residue in the kettle.

[0210] (Step 1) To the obtained residue in the kettle, 300 g of toluene was added to obtain a homogeneous solution O. This homogeneous solution O was maintained at 80 °C, and then the temperature was gradually lowered to 5 °C to obtain a slurry. The obtained slurry was filtered using a centrifuge to obtain 252 g of a crude cake O and 280 g of a crude crystallization mother liquor. When analyzing the polymer amount in this crude cake O, components with a molecular weight of 10,000 or more were detected at 1.8% by mass, and it was found that 4.5 g (1.8% by mass × 252 g of crude cake ÷ 100 = 4.5 g) of PMMA was contained in the crude cake O. The removal rate of PMMA by obtaining the crude cake was 77% by mass (100 - 4.5 g / 19.4 g × 100 = 77% by mass).

[0211] (Step 2) 600 g of toluene heated to 60 °C was sprinkled on the crude cake O to wash the crude cake, and 226 g of a refined cake O was obtained. When analyzing the polymer amount in this refined cake O, components with a molecular weight of 10,000 or more were below the detection limit (0.1% by mass or less). The removal rate of PMMA was 99% by mass or more. As a result of subjecting a part of the crude cake after washing to composition analysis by high performance liquid chromatography, it was confirmed that it was an adduct crystal in which phenol was added to bisphenol A.

[0212] (Adsorption purification step) The obtained purified cake O was returned to a jacketed separable flask equipped with a Liebig condenser, stirring blades, and a thermometer. 600 g of toluene and 80 g of water were added, and the mixture was heated to 80°C to dissolve it, obtaining organic phase O1 (bisphenol solution) containing bisphenol A. This organic phase O1 was gradually supplied to a glass filter lined with 20g of activated carbon, and filtered by suction to obtain organic phase O2 (adsorbed purified solution). The filterability was good.

[0213] (Water washing process) The obtained organic phase O2 was returned to the separable flask, 120 g of water was added, and the mixture was stirred for 15 minutes while maintaining the temperature at 75°C. After standing for 10 minutes, the two phases were separated to obtain the organic phase and the aqueous phase. This procedure was repeated three times to obtain the organic phase O3. The aqueous phase from the fourth extraction was transferred to a heat-resistant bottle, cooled to 25°C, and its electrical conductivity was measured to be 1.8 μS / cm.

[0214] (Crystallization process) Subsequently, the organic phase O3 was cooled to 10°C to obtain a slurry. The obtained slurry was filtered to obtain 134 g of cake. The resulting cake was dried using a rotary evaporator at 85°C for 5 hours to obtain 107 g of bisphenol A. The yield was 60 mol% (107 g ÷ 228 g / mol ÷ 0.787 × 100 = 60 mol%). When the obtained bisphenol A was analyzed by gas chromatography, the toluene content was found to be 500 ppm by mass.

[0215] [Comparative Example 6] (Depolymerization process) The procedure was carried out under the same conditions as in Example 10, and the formation of bisphenol A was confirmed.

[0216] Dilute sulfuric acid was added to the obtained decomposition solution until the aqueous phase reached pH 6. The solution was then filtered using a glass filter equipped with a vacuum pump to obtain 645 g of homogeneous solution. A portion of this homogeneous solution was analyzed for composition using GPC, and 3.0% by mass of components with a molecular weight of 10,000 or more was detected. It was found that the homogeneous solution contained 19.4 g of PMMA (3.0% by mass × 645 g homogeneous solution ÷ 100 = 19.4 g).

[0217] The homogeneous liquid was transferred to a distillation apparatus equipped with a thermometer, stirring blade, distillation tube, and pressure regulator. The pressure was reduced from atmospheric pressure (760 Torr) to 120 Torr, and while monitoring the distillation rate, the internal temperature was raised from room temperature to 80°C. 290g of the fraction was then withdrawn, and the residue in the still was obtained.

[0218] (Process 1) To the resulting residue, 360 g of toluene was added to obtain a homogeneous solution P. This homogeneous solution P was maintained at 80°C, and then the temperature was gradually lowered to 5°C to obtain a slurry. The obtained slurry was filtered using a centrifuge to obtain 162 g of crude cake P and 557 g of crude crystallization mother liquor. Analysis of the polymer content in this crude cake P revealed that 11.7 mass% of components with a molecular weight of 10,000 or more were detected, and it was found that crude cake P contained 19.0 g of PMMA (11.7 mass% × crude cake 162 g ÷ 100 = 19.0 g). The PMMA removal rate by obtaining the crude cake was 2 mass% (100 - 19.0 g / 19.4 g × 100 = 2 mass%).

[0219] (Process 2) 450g of toluene heated to 60°C was sprinkled onto the crude cake P, and the crude cake was washed to obtain 158g of refined cake P. Analysis of the polymer content in this refined cake P revealed that 11.6% by mass of components with a molecular weight of 10,000 or more was detected, and it was found that the crude cake P contained 18.3g of PMMA (11.6% by mass × 158g crude cake ÷ 100 = 18.3g). The PMMA removal rate by obtaining the refined cake was 6% by mass (100 - 18.3g / 19.4g × 100 = 6% by mass).

[0220] (Adsorption purification process) The obtained refined cake P was returned to a jacketed separable flask equipped with a Dimroth condenser, a stirring blade, and a thermometer, 600 g of toluene was added, and the mixture was heated to 80 °C and dissolved to obtain an organic phase P1 (bisphenol A solution) containing bisphenol A. This organic phase P1 was gradually supplied to a glass filter filled with 20 g of activated carbon and subjected to suction filtration to obtain an organic phase P2 (adsorption-refined solution). At this time, the filtration rate decreased during filtration, and it took about three times as long as in Examples 9 and 10 to adsorptively purify the entire amount of the organic phase P1.

[0221] (Water washing step) The obtained organic phase P2 was returned to the separable flask again, 120 g of water was added, and the mixture was stirred for 15 minutes while maintaining the temperature at 75 °C, then allowed to stand for 10 minutes for two-phase separation to obtain an organic phase and an aqueous phase. This operation was repeated three times to obtain an organic phase P3. The fourth aqueous phase was taken out into a heat-resistant flask, cooled to 25 °C, and its electric conductivity was measured to be 5.2 μS / cm.

[0222] (Crystallization step) Thereafter, the temperature of the organic phase P3 was lowered to 10 °C to obtain a slurry. The obtained slurry was filtered to obtain 155 g of a cake. The obtained cake was held at 85 °C for 5 hours using a rotary evaporator for drying, but bisphenol A remained in the form of a cake. When this dried bisphenol A was analyzed using gas chromatography, the toluene content was 18% by mass.

[0223]

Table 2

[0224] [Example 11] (Depolymerization step) In a jacketed separable flask equipped with a Liebig condenser, stirring blades, and a thermometer, 120 g of polycarbonate resin (since the repeating units of polycarbonate resin are 254 g / mol, 120 g ÷ 254 g / mol = 0.472 moles), 107 g of sodium bicarbonate aqueous solution adjusted to 7% by mass, 360 g of phenol, 2.4 g of dodecanethiol, and 12 g of PC / ABS alloy pellets (PC content 70% by mass: 1.2 g × 70% by mass ÷ 100 ÷ 254 g / mol = 0.003 moles) were placed at room temperature under a nitrogen atmosphere. The reaction solution was in the form of a slurry. Subsequently, the internal temperature was raised to 90°C, and the reaction was allowed to proceed for 4 hours while maintaining this temperature to obtain the decomposition solution. The decomposition solution was cloudy and not a homogeneous solution. This decomposition solution was filtered using a glass filter equipped with a vacuum pump, and 575 g of the resulting filtrate was prepared as homogeneous solution Q. A portion of this homogeneous solution Q was analyzed for composition by high-performance liquid chromatography to confirm the formation of bisphenol A.

[0225] (Process 1) The obtained homogeneous solution Q was gradually cooled from 90°C to 10°C to obtain a slurry. The obtained slurry was filtered to obtain 187 g of crude cake Q (solid component) and 345 g of crude crystallization mother liquor.

[0226] (Process 2) 450g of desalted water heated to 60°C was sprinkled onto crude cake Q to wash the crude cake, yielding 131g of refined cake Q. A portion of this refined cake Q was analyzed by high-performance liquid chromatography and confirmed to be an adduct crystal in which phenol was added to bisphenol A.

[0227] (Adsorption purification process) The obtained purified cake Q was returned to a jacketed separable flask equipped with a Liebig condenser, stirring blades, and a thermometer. 600 g of toluene was added, and the mixture was heated to 75°C to dissolve it, obtaining organic phase Q1 (bisphenol solution) containing bisphenol A. This organic phase Q1 was gradually supplied to a glass filter lined with 20g of activated carbon, and suction filtration was performed to obtain organic phase Q2 (adsorbed purified liquid). The filtration performance was good.

[0228] (Water washing process) The obtained organic phase Q2 was returned to the separable flask, 100g of water was added, and the mixture was stirred for 15 minutes while maintaining the temperature at 75°C. After standing for 10 minutes, the two phases were separated to obtain the organic phase and the aqueous phase. This procedure was repeated three times to obtain the organic phase Q3. The aqueous phase from the fourth extraction was transferred to a heat-resistant bottle, cooled to 25°C, and its electrical conductivity was measured to be 1.5 μS / cm.

[0229] (Crystallization process) Subsequently, the organic phase Q3 was cooled to 10°C to obtain a slurry. The obtained slurry was filtered to obtain 72 g of cake. The resulting cake was dried using a rotary evaporator at 85°C for 5 hours to obtain 58 g of bisphenol A. The yield was 54 mol% (58 g ÷ 228 g / mol ÷ 0.475 mol × 100 = 54 mol%). Analysis of the obtained bisphenol A using gas chromatography revealed a toluene content of 500 ppm by mass. Furthermore, analysis of the polymer content in the dried bisphenol A (product BPA) showed that components with a molecular weight of 10,000 or more were below the detection limit (0.1% by mass or less).

[0230] [Example 12] (Depolymerization process) In a jacketed separable flask equipped with a Liebig condenser, stirring blades, and a thermometer, 120 g of polycarbonate resin (since the repeating units of polycarbonate resin are 254 g / mol, 120 g ÷ 254 g / mol = 0.472 moles), 107 g of sodium bicarbonate aqueous solution adjusted to 7% by mass, 360 g of phenol, 2.4 g of dodecanethiol, and 12 g of PC / PET alloy pellets (PC content 68% by mass: 1.2 g × 68% by mass ÷ 100 ÷ 254 g / mol = 0.003 moles) were placed at room temperature under a nitrogen atmosphere. The reaction solution was in the form of a slurry. Subsequently, the internal temperature was raised to 90°C, and the reaction was carried out for 4 hours while maintaining this temperature to obtain a homogeneous decomposition solution. This decomposition solution was filtered using a glass filter equipped with a vacuum pump, and 586 g of the resulting filtrate was prepared as homogeneous solution R. A portion of this homogeneous solution R was analyzed for composition by high-performance liquid chromatography to confirm the formation of bisphenol A.

[0231] (Process 1) The obtained homogeneous solution R was gradually cooled from 90°C to 10°C to obtain a slurry. The obtained slurry was filtered to obtain 179 g of crude cake R (solid component) and 373 g of crude crystallization mother liquor.

[0232] (Process 2) 450g of desalted water heated to 60°C was sprinkled onto the crude cake R to wash it, and 141g of refined cake R was obtained. A portion of this refined cake R was analyzed for composition by high-performance liquid chromatography and confirmed to be an adduct crystal in which phenol was added to bisphenol A.

[0233] (Adsorption purification process) The obtained purified cake R was returned to a jacketed separable flask equipped with a Liebig condenser, stirring blades, and a thermometer. 600 g of toluene was added, and the mixture was heated to 75°C to dissolve it, obtaining organic phase R1 (bisphenol solution) containing bisphenol A. This organic phase R1 was gradually supplied to a glass filter lined with 20g of activated carbon, and suction filtration was performed to obtain organic phase R2 (adsorbed purified liquid). The filtration performance was good.

[0234] (Water washing process) The obtained organic phase R2 was returned to the separable flask, 100g of water was added, and the mixture was stirred for 15 minutes while maintaining the temperature at 75°C. After standing for 10 minutes, the two phases were separated to obtain the organic phase and the aqueous phase. This procedure was repeated three times to obtain the organic phase R3. The aqueous phase from the fourth extraction was transferred to a heat-resistant bottle, cooled to 25°C, and its electrical conductivity was measured to be 2.1 μS / cm.

[0235] (Crystallization process) Subsequently, the organic phase R3 was cooled to 10°C to obtain a slurry. The obtained slurry was filtered to obtain 78 g of cake. The resulting cake was dried using a rotary evaporator at 85°C for 5 hours to obtain 63 g of bisphenol A. The yield was 58 mol% (63 g ÷ 228 g / mol ÷ 0.475 mol × 100 = 58 mol%). Analysis of the obtained bisphenol A using gas chromatography revealed a toluene content of 500 ppm by mass. Furthermore, analysis of the polymer content in the dried bisphenol A showed that components with a molecular weight of 10,000 or more were below the detection limit (0.1% by mass or less).

[0236] [Example 13] (Depolymerization process) In a jacketed separable flask equipped with a Liebig condenser, stirring blades, and a thermometer, 120 g of polycarbonate resin (since the repeating units of polycarbonate resin are 254 g / mol, 120 g ÷ 254 g / mol = 0.472 moles), 107 g of sodium bicarbonate aqueous solution adjusted to 7% by mass, 360 g of phenol, 2.4 g of dodecanethiol, and 12 g of PC / PBT alloy pellets (PC content 67% by mass: 1.2 g × 67% by mass ÷ 100 ÷ 254 g / mol = 0.003 moles) were placed at room temperature under a nitrogen atmosphere. The reaction solution was in the form of a slurry. Subsequently, the internal temperature was raised to 90°C, and the reaction was carried out for 4 hours while maintaining this temperature to obtain a decomposition solution. The decomposition solution was in a suspended state. This decomposition solution was filtered using a glass filter equipped with a vacuum pump, and 572 g of the resulting filtrate was prepared as homogeneous solution S. A portion of this homogeneous solution S was analyzed for composition by high-performance liquid chromatography to confirm the formation of bisphenol A.

[0237] (Process 1) The obtained homogeneous solution S was gradually cooled from 90°C to 10°C to obtain a slurry. The obtained slurry was filtered to obtain 175 g of crude cake S (solid component) and 368 g of crude crystallization mother liquor.

[0238] (Process 2) 450g of desalted water heated to 60°C was sprinkled onto the crude cake S to wash it, and 136g of refined cake S was obtained. A portion of this refined cake S was analyzed for composition by high-performance liquid chromatography and confirmed to be an adduct crystal in which phenol was added to bisphenol A.

[0239] (Adsorption purification process) The obtained purified cake S was returned to a jacketed separable flask equipped with a Liebig condenser, stirring blades, and a thermometer. 600 g of toluene was added, and the mixture was heated to 75°C to dissolve it, obtaining organic phase S1 (bisphenol solution) containing bisphenol A. This organic phase S1 was gradually supplied to a glass filter lined with 20g of activated carbon, and suction filtration was performed to obtain organic phase S2 (adsorbed purified liquid). The filtration performance was good.

[0240] (Water washing process) The obtained organic phase S2 was returned to the separable flask, 100g of water was added, and the mixture was stirred for 15 minutes while maintaining the temperature at 75°C. After standing for 10 minutes, the two phases were separated to obtain the organic phase and the aqueous phase. This procedure was repeated three times to obtain the organic phase S3. The aqueous phase from the fourth extraction was transferred to a heat-resistant bottle, cooled to 25°C, and its electrical conductivity was measured to be 1.8 μS / cm.

[0241] (Crystallization process) Subsequently, the organic phase S3 was cooled to 10°C to obtain a slurry. The obtained slurry was filtered to obtain 73 g of cake. The resulting cake was dried using a rotary evaporator at 85°C for 5 hours to obtain 60 g of bisphenol A. The yield was 55 mol% (60 g ÷ 228 g / mol ÷ 0.475 mol × 100 = 55 mol%). Analysis of the obtained bisphenol A using gas chromatography revealed a toluene content of 500 ppm by mass. Furthermore, analysis of the polymer content in the dried bisphenol A showed that components with a molecular weight of 10,000 or more were below the detection limit (0.1% by mass or less).

[0242] [Table 3]

[0243] [Example 14] In a 150 mL glass reaction vessel equipped with a stirrer and distillation tube, 60 g of bisphenol A obtained in Example 9, 45 g of bisphenol A manufactured by Mitsubishi Chemical Corporation (0.46 mol as bisphenol A), 107.4 g (0.50 mol) of diphenyl carbonate, and 7 μL of a 400 ppm by mass aqueous solution of cesium carbonate were added. The glass reaction vessel was reduced to approximately 100 Pa, and then the pressure was restored to atmospheric pressure with nitrogen, a process that was repeated three times to replace the inside of the reaction vessel with nitrogen. After that, the reaction vessel was immersed in an oil bath at 220°C to dissolve the contents.

[0244] The stirrer was set to rotate at 100 revolutions per minute, and while distilling off the phenol produced as a by-product by the oligomerization reaction of bisphenol A and diphenyl carbonate in the reaction vessel, the pressure inside the reaction vessel was reduced from an absolute pressure of 101.3 kPa to 13.3 kPa over a period of 40 minutes. Next, the pressure in the reaction vessel was maintained at 13.3 kPa, and the transesterification reaction was carried out for 80 minutes while the phenol was further removed by distillation.

[0245] Subsequently, the external temperature of the reaction vessel was raised to 290°C, and the internal pressure of the reaction vessel was reduced from 13.3 kPa to 399 Pa (absolute pressure) over 40 minutes to remove the distilled phenol from the system.

[0246] Subsequently, the absolute pressure in the reaction vessel was reduced to 30 Pa, and the polycondensation reaction was carried out. The polycondensation reaction was terminated when the stirrer in the reaction vessel reached a predetermined stirring power. The time from raising the temperature to 290°C to the completion of polymerization was 133 minutes.

[0247] Next, the reaction vessel was repressurized to an absolute pressure of 101.3 kPa using nitrogen, then increased to a gauge pressure of 0.2 MPa, and the polycarbonate resin was extracted from the reaction vessel to obtain the polycarbonate resin. The viscosity-average molecular weight (Mv) of the obtained polycarbonate resin was 20170, and the pellet YI was 12.9.

[0248] [Example 15] As the polycarbonate resin composite, an acrylic cured polycarbonate resin composition was used. For the acrylic cured polycarbonate resin composition, Mitsubishi Chemical Engineering Plastics Corporation's polycarbonate resin "NOVAREX® M7022J" was used to form a 60mm x 60mm x 3mm plate, Mitsubishi Chemical Corporation's "AcryKing®" was applied, dried, and then cured by UV irradiation. The resulting plate was then cut into pieces of approximately 5-10mm in size for use.

[0249] (Depolymerization process) In a jacketed separable flask equipped with a Liebig condenser, stirring blades, and a thermometer, 199 g of acrylic cured polycarbonate resin composition (since the repeating units of polycarbonate resin are 254 g / mol, 199 g ÷ 254 g / mol = 0.783 moles), 88.1 g of sodium bicarbonate aqueous solution adjusted to 7% by mass, 299 g of phenol, and 2.0 g of dodecanethiol were added at room temperature under a nitrogen atmosphere. The reaction solution was in the form of a slurry. Subsequently, the internal temperature was raised to 90°C, and the reaction was allowed to proceed for 4 hours while maintaining this temperature to obtain the decomposition solution. The decomposition solution was cloudy and not a homogeneous solution. This decomposition solution was filtered using a glass filter equipped with a vacuum pump, and 553 g of the resulting filtrate was prepared as homogeneous solution T. A portion of this homogeneous solution T was analyzed for composition by high-performance liquid chromatography to confirm the formation of bisphenol A.

[0250] (Process 1) The obtained homogeneous solution T was gradually cooled from 90°C to 10°C to obtain a slurry. The obtained slurry was filtered to obtain 226.7 g of crude cake T (solid component) and 313.4 g of crude crystallization mother liquor.

[0251] (Process 2) 400g of desalted water heated to 60°C was sprinkled onto the crude cake T to wash it, and 201.5g of refined cake T was obtained. A portion of this refined cake T was analyzed for composition by high-performance liquid chromatography and confirmed to be an adduct crystal in which phenol was added to bisphenol A.

[0252] (Adsorption purification process) The obtained purified cake T was returned to a jacketed separable flask equipped with a Liebig condenser, stirring blades, and a thermometer. 600 g of toluene was added, and the mixture was heated to 75°C to dissolve it, obtaining organic phase T1 (bisphenol solution) containing bisphenol A. This organic phase T1 was gradually supplied to a glass filter lined with 40g of activated carbon, and suction filtration was performed to obtain organic phase T2 (adsorbent purified solution). The filtration performance was good.

[0253] (Water washing process) The obtained organic phase T2 was returned to the separable flask, 100g of water was added, and the mixture was stirred for 15 minutes while maintaining the temperature at 75°C. After standing for 10 minutes, the two phases were separated to obtain the organic phase and the aqueous phase. This procedure was repeated three times to obtain the organic phase T3. The aqueous phase from the fourth extraction was transferred to a heat-resistant bottle, cooled to 25°C, and its electrical conductivity was measured to be 2.1 μS / cm.

[0254] (Crystallization process) Subsequently, the organic phase T3 was cooled to 10°C to obtain a slurry. The obtained slurry was filtered, and 300g of toluene was added to the resulting cake for suspension washing, followed by filtration to obtain 117g of cake. The resulting cake was dried using a rotary evaporator at 85°C for 5 hours to obtain 1 g of bisphenol A. The yield was 57 mol% (101 g ÷ 228 g / mol ÷ 0.783 moles × 100 = 57 mol%). Analysis of the obtained bisphenol A using gas chromatography revealed a toluene content of 400 ppm by mass. Furthermore, analysis of the polymer content in the dried bisphenol A (product BPA) showed that components with a molecular weight of 10,000 or more were below the detection limit (0.1% by mass or less).

[0255] [Example 16] As the polycarbonate resin composite, an organic microparticle-containing polycarbonate resin composition was used. The organic microparticle-containing polycarbonate resin composition was prepared using the polycarbonate resin "NOVAREX® M7022J" from Mitsubishi Chemical Engineering Plastics Corporation. Spherical organic microparticles (GM-0205S, manufactured by Aica Kogyo Co., Ltd.) were added at a concentration of 0.5% by mass relative to the polycarbonate resin. After mixing in a tumbler for 20 minutes, the mixture was supplied to a Japan Steel Works Ltd. (TEX30HSST) equipped with one vent, kneaded under the conditions of a screw rotation speed of 200 rpm, a discharge rate of 15 kg / hour, and a barrel temperature of 280°C. The molten resin extruded into strands was rapidly cooled in a water bath and pelletized using a pelletizer.

[0256] (Depolymerization process) In a jacketed separable flask equipped with a Liebig condenser, stirring blades, and a thermometer, 199 g of polycarbonate resin composition containing organic microparticles (since the repeating units of polycarbonate resin are 254 g / mol, 199 g ÷ 254 g / mol = 0.783 moles), 88.1 g of sodium bicarbonate aqueous solution adjusted to 7% by mass, and 299 g of phenol were placed at room temperature under a nitrogen atmosphere. The reaction solution was in the form of a slurry. Subsequently, the internal temperature was raised to 90°C, and the reaction was carried out for 4 hours while maintaining this temperature to obtain a homogeneous decomposition solution. This decomposition solution was filtered using a glass filter equipped with a vacuum pump, and 548 g of the resulting filtrate was prepared as homogeneous solution U. A portion of this homogeneous solution U was analyzed for composition by high-performance liquid chromatography to confirm the formation of bisphenol A.

[0257] (Process 1) The obtained homogeneous solution U was gradually cooled from 90°C to 10°C to obtain a slurry. The obtained slurry was filtered to obtain 277 g of crude cake U (solid component) and 272 g of crude crystallization mother liquor.

[0258] (Process 2) 450g of desalted water heated to 60°C was sprinkled onto the crude cake U to wash it, and 236g of refined cake U was obtained. A portion of this refined cake U was analyzed for composition by high-performance liquid chromatography and confirmed to be an adduct crystal in which phenol was added to bisphenol A.

[0259] (Adsorption purification process) The obtained purified cake U was returned to a jacketed separable flask equipped with a Liebig condenser, stirring blades, and a thermometer. 600 g of toluene was added, and the mixture was heated to 75°C to dissolve it, obtaining organic phase U1 (bisphenol solution) containing bisphenol A. This organic phase U1 was gradually supplied to a glass filter lined with 40g of activated carbon, and filtered by suction to obtain organic phase U2 (adsorbent purified liquid). The filterability was good.

[0260] (Water washing process) The obtained organic phase U2 was returned to the separable flask, 100g of water was added, and the mixture was stirred for 15 minutes while maintaining the temperature at 75°C. After standing for 10 minutes, the two phases were separated to obtain the organic phase and the aqueous phase. This procedure was repeated three times to obtain the organic phase U3. The aqueous phase from the fourth extraction was transferred to a heat-resistant bottle, cooled to 25°C, and its electrical conductivity was measured to be 2.2 μS / cm.

[0261] (Crystallization process) Subsequently, the organic phase U3 was cooled to 10°C to obtain a slurry. The obtained slurry was filtered, and 300g of toluene was added to the resulting cake for suspension washing, followed by filtration to obtain 141g of cake. The resulting cake was dried using a rotary evaporator at 85°C for 5 hours to obtain 120 g of bisphenol A. The yield was 67 mol% (120 g ÷ 228 g / mol ÷ 0.783 mol × 100 = 67 mol%). Analysis of the obtained bisphenol A using gas chromatography revealed a toluene content of 500 ppm by mass. Furthermore, analysis of the polymer content in the dried bisphenol A showed that components with a molecular weight of 10,000 or more were below the detection limit (0.1% by mass or less).

Claims

1. A method for producing bisphenol, comprising removing a resin other than bisphenol and polycarbonate resin (hereinafter referred to as "other resin") from a mixed solution containing the other resin, The other resin is at least one selected from the group consisting of acrylic resin, polyethylene terephthalate, polybutylene terephthalate, ABS resin, polyamide, phenolic resin, polyurethane, polylactic acid, and silicone resin. The process includes step 1, in which the bisphenol and the other resin are dissolved in a solvent containing an aromatic monoalcohol to obtain an aromatic monoalcohol-containing solution, from which the bisphenol is precipitated to obtain a bisphenol slurry, and then the bisphenol slurry is subjected to solid-liquid separation to obtain a crude bisphenol cake and a mother liquor in which the other resin is dissolved. Before precipitating the bisphenol, the mixed solution or the aromatic monoalcohol-containing solution is subjected to solid-liquid separation to obtain a homogeneous solution. A method for producing bisphenol, wherein the homogeneous solution contains other resins which are polymers having a molecular weight of 10,000 or more on a standard polystyrene basis, as quantified by the GPC method.

2. Prior to step 1, the process includes a depolymerization step in which the polycarbonate resin in a polycarbonate resin composite containing the polycarbonate resin and the other resin is depolymerized to obtain a decomposition solution containing the bisphenol and the other resin. The depolymerization temperature is 20 to 180°C. The method for producing bisphenol according to claim 1, wherein the mixed solution is the decomposition solution.

3. The mixed solution is obtained by carrying out the depolymerization in the presence of the aromatic monoalcohol during the depolymerization step. The method for producing bisphenol according to claim 2, wherein the aromatic monoalcohol-containing solution is the mixed solution.

4. The mixed solution is obtained by carrying out the depolymerization step in the absence of the aromatic monoalcohol. The method for producing bisphenol according to claim 2, wherein the aromatic monoalcohol-containing solution is obtained by solvent substitution of the solvent in the obtained mixed solution with the aromatic monoalcohol.

5. The method for producing bisphenol according to any one of claims 2 to 4, wherein the polycarbonate resin composite is one or more selected from the group consisting of (c1) to (c8) below. (c1) Molded article of the polymer alloy of the polycarbonate resin and the other resin (c2) A resin molded body in which the surface of the polycarbonate resin molded body is coated with the other resin. (c3) A resin molded body in which a polymer alloy of the polycarbonate resin and the other resin is coated on the surface of the molded body of the polycarbonate resin. (c4) A resin molded body in which the surface of a polymer alloy molded body of the polycarbonate resin and the other resin is coated with the other resin. (c5) A resin molded body in which the surface of a molded body of a polymer alloy of polycarbonate resin and the other resin is coated with the polymer alloy of polycarbonate resin and the other resin. (c6) A resin molded body in which the surface of a polymer alloy molded body of the polycarbonate resin and the other resin is coated with the polycarbonate resin. (c7) A resin molded body in which the polycarbonate resin is coated on the surface of the molded body of the other resin. (c8) A resin molded body in which a polymer alloy of the polycarbonate resin and the other resin is coated on the surface of the molded body of the other resin.

6. The method for producing bisphenol according to claim 1 or 2, wherein the aromatic monoalcohol comprises phenol or cresol.

7. The aforementioned aromatic monoalcohol is phenol, A method for producing bisphenol according to claim 1 or 2, wherein in step 1, the bisphenol is precipitated as an adduct crystal consisting of the bisphenol and phenol, and a crude cake of the adduct crystal consisting of the bisphenol and phenol is obtained.

8. A method for producing bisphenol according to claim 1 or 2, wherein the molar ratio of the content of the aromatic monoalcohol to the bisphenol content in the aromatic monoalcohol-containing solution for precipitating bisphenol is 1.0 or more.

9. A method for producing bisphenol according to claim 1 or 2, further comprising step 2 after step 1, of supplying a washing solution to the crude bisphenol cake, washing the crude bisphenol cake, and obtaining a refined bisphenol cake.

10. The method for producing bisphenol according to claim 10, wherein the washing solution is at least one selected from the group consisting of aromatic monoalcohols, aliphatic monoalcohols, ketones, aromatic hydrocarbons, aliphatic hydrocarbons, and water.

11. A method for producing bisphenol according to claim 1 or 2, comprising the steps of: dissolving or melting the crude bisphenol cake or the refined cake obtained by washing the crude cake in a solvent to obtain a bisphenol solution; and then contacting the bisphenol solution with a solid adsorbent to obtain an adsorption-purified solution.

12. The method for producing bisphenol according to claim 1 or 2, wherein the bisphenol is 2,2-bis(4-hydroxyphenyl)propane.

13. A step of obtaining bisphenol by the method for producing bisphenol according to claim 1 or 2, A method for producing recycled polycarbonate resin, comprising the step of producing recycled polycarbonate resin using the obtained bisphenol raw material containing bisphenol.

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