Method for producing bisphenol and method for producing polycarbonate resin

Abstract

Provided are: a method for producing a bisphenol with which it is possible to obtain a bisphenol having a good color tone; and a method for producing a polycarbonate resin using the resulting bisphenol. A method for producing bisphenol, which comprises an adsorption purification step for obtaining an adsorption purified solution by bringing an adsorption purified solution containing bisphenol and an organic solvent into contact with an adsorbent and purifying the adsorption purified solution, the adsorption purified solution being alkaline. Also provided is a method for producing a polycarbonate resin, which comprises: a step for obtaining a bisphenol by the aforementioned method for producing a bisphenol; and a step for producing a polycarbonate resin using a bisphenol starting material containing the obtained bisphenol.

Description

Technical Field

[0001] The present invention relates to a method for producing bisphenol and a method for producing a polycarbonate resin. Background Art

[0002] Plastics are indispensable in modern society due to their excellent functions and properties. They are produced and consumed in large quantities not only in Japan but also around the world. For sustainable development, it is important to recycle the plastic resources after consumption. As means of this, there are three main methods: material recycling of plastics after consumption as raw materials for plastic products, chemical recycling of plastics as chemical raw materials, and thermal recycling as energy.

[0003] Regarding the effective utilization rate of waste plastics through various recycling methods in Japan, thermal recycling has the highest effective utilization rate. The heat released when plastics are burned is not inferior to that of coal and oil, and the heat is effectively used for power generation, etc. However, in Europe and the United States, thermal recycling is often not considered recycling, and further promotion of material recycling and chemical recycling is sought. 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 has excellent processability and durability, and is highly transparent. Therefore, it is used not only in housings of household electrical appliances and optical recording disks (CDs, etc.), but also in automotive headlight covers, roofing materials for parking lots, and soundproof walls on highways that are used outdoors for a long time.

[0005] Various methods for material recycling and chemical recycling of polycarbonate resins have been reported. As methods for material recycling, known ones include: a method of recovering the polycarbonate resin serving as a substrate by treating an optical recording disk with an alkaline aqueous solution to remove a coating agent on the surface (Patent Document 1); a method of similarly recovering only the polycarbonate resin by dissolving the optical recording disk in a solvent and then precipitating it using a mixed solution containing water and alcohol (Patent Document 2), etc.

[0006] In addition, as methods for chemical recycling, known methods include: a method of hydrolyzing waste polycarbonate resin and recovering it in the form of an alkaline aqueous solution containing a sodium salt of bisphenol (Patent Document 3); a method of alcoholyzing an optical recording disk and recovering bisphenol and dialkyl carbonate (Patent Document 4); a method of phenolyzing waste polycarbonate resin and recovering bisphenol and diphenyl carbonate (Patent Document 5), etc.

[0007] Prior art literature

[0008] Patent Literature

[0009] Patent Document 1: Japanese Patent Application Publication No. 2001-310970

[0010] Patent Document 2: Japanese Patent Application Publication No. 2009-84538

[0011] Patent Document 3: Japanese Patent Application Publication No. 2005-179460

[0012] Patent Document 4: Japanese Patent Application Publication No. 2001-160243

[0013] Patent Document 5: Japanese Patent Application Laid-Open No. 7-207059 Summary of the invention

[0014] Problem that the invention aims to solve

[0015] Polycarbonate resin used outdoors for a long time gradually deteriorates from the surface of the material due to wind and rain, causing discoloration and low molecular weight. The deteriorated surface originally has the same composition and properties as the polycarbonate resin in the non-deteriorated part. Therefore, it is difficult to separate the polycarbonate resin from the deteriorated part derived from the polycarbonate resin by removing additives such as metal coatings and flame retardants.

[0016] Bisphenol obtained by depolymerizing waste polycarbonate resin with degraded surface is inferior to pure product in color tone and is therefore not preferred. It is not impossible to remove coloring components by repeated purification such as crystallization and extraction, but the manufacturing process becomes complicated and it will lead to loss of bisphenol and increase of waste, which is not economical. Therefore, a purification method for removing coloring components in bisphenol in a simple and efficient manner is sought.

[0017] In addition, polycarbonate resins may be colored to any color using pigments and dyes, or given specific functions by adding additives such as light diffusing materials, or may have metal coatings such as aluminum formed on the surface of polycarbonate resins, depending on the application. Even if it is unused factory scraps, polycarbonate resins that have undergone such processing are difficult to restore to the original transparent polycarbonate resin through material recycling, and the current situation is that they are colored to a darker color for multi-stage recycling or discarded.

[0018] Even chemical recycling is not easy to completely remove pigments and light diffusing materials, which are fine particles with a particle size of nanometers to micrometers. In addition, aluminum becomes an inhibitory factor when polymerizing polycarbonate, so it is required to control it to an extremely low concentration (less than 1 mass ppm).

[0019] The present invention has been made in view of the above-mentioned existing actual situation, and its object is to provide a method for producing bisphenol that can obtain bisphenol with good color tone. In addition, a method for producing a polycarbonate resin using the bisphenol as a raw material is provided.

[0020] Solutions for solving problems

[0021] The present inventors have conducted intensive studies to solve the above problems and have found that by bringing an organic phase in which bisphenol containing a coloring component is dissolved into contact with an adsorbent in an appropriate state, the coloring component can be selectively adsorbed and removed, thereby reducing the amount of wastewater discharged in the purification process.

[0022] That is, the present invention relates to the following technical solutions.

[0023] <1> A method for producing bisphenol, characterized in that it has the following adsorption purification step: a purified liquid to be adsorbed containing bisphenol and an organic solvent is brought into contact with an adsorbent material, the purified liquid to be adsorbed is purified to obtain an adsorbed purified liquid, and the purified liquid to be adsorbed is alkaline.

[0024] <2> According to the aforementioned <1> The method for producing bisphenol, wherein the pH of the adsorbed purified liquid is above 7.1.

[0025] <3> According to the aforementioned <1> or <2> In the method for producing bisphenol, the adsorbed purified liquid contains a bisphenol analog, and the bisphenol analog has a structure in which at least two carbon atoms on the benzene ring constituting the bisphenol skeleton form double bonds with oxygen atoms.

[0026] <4> According to the aforementioned <1> ~ <3> The method for producing bisphenol according to any one of the preceding claims, wherein the content of water in the adsorbed purified liquid is 10% by mass or less.

[0027] <5> According to the aforementioned <1> ~ <4> The method for producing bisphenol according to any one of the above aspects, wherein the content of the organic solvent in the adsorbed purified liquid is 20% by mass or more.

[0028] <6> According to the aforementioned <1> ~ <5> The method for producing bisphenol according to any one of the above, wherein the organic solvent comprises at least one selected from the group consisting of benzene, toluene, xylene, phenol, cresol, dichloromethane, dimethyl carbonate and diethyl carbonate.

[0029] <7> According to the aforementioned <1> ~ <6> The method for producing bisphenol according to any one of the above aspects, wherein the adsorbent comprises any one selected from the group consisting of activated clay, acid clay, activated carbon, and a cation exchange resin.

[0030] <8> According to the aforementioned <1> ~ <7> The method for producing bisphenol described in any one of the above has the following decomposition step: before the adsorption purification step, the raw material resin in the decomposition raw material containing the raw material resin is chemically decomposed to obtain the bisphenol, wherein the raw material resin is a polycarbonate resin and / or an epoxy resin.

[0031] <9> According to the aforementioned <8> In the method for producing bisphenol, the raw material for decomposition is waste plastic containing the raw material resin.

[0032] <10> According to the aforementioned <9> In the method for producing bisphenol, the waste plastic has a metal layer and / or a resin layer formed of a resin other than the raw material resin.

[0033] <11> According to the aforementioned <8> ~ <10> The method for producing bisphenol according to any one of the preceding claims, wherein the decomposition raw material is a resin composition containing the raw material resin and fine particles and / or a polar low molecular weight compound.

[0034] <12> According to the aforementioned <8> ~ <11> The method for producing bisphenol according to any one of the preceding claims, wherein the decomposition raw material is a resin composition containing the raw material resin and one or more selected from the group consisting of a light diffusing material, an ultraviolet absorber, and a coloring agent.

[0035] <13> According to the aforementioned <8> ~ <12> The method for producing bisphenol described in any one of the preceding claims, wherein the value obtained by multiplying the Hazen color (APHA) of a dichloromethane solution having a concentration of 10% by mass of the above-mentioned decomposition raw material by 10 is 200 or more, and the Hazen color (APHA) of a molten liquid obtained by heating and melting the above-mentioned bisphenol produced at 175° C. for 30 minutes is 100 or less.

[0036] <14> According to the aforementioned <8> ~ <13> The method for producing bisphenol according to any one of the preceding claims, wherein the lightness (L*) of a dichloromethane solution containing the decomposition raw material at a concentration of 10% by mass is 80 or less, and the lightness (L*) of a melt obtained by heating and melting the produced bisphenol at 175° C. for 30 minutes is 90 or more.

[0037] <15> According to the aforementioned <8> ~ <14> The method for producing bisphenol described above comprises decomposing the raw material resin in the presence of at least one decomposing agent selected from the group consisting of water, aromatic monohydric alcohols and aliphatic monohydric alcohols.

[0038] <16> According to the aforementioned <8> ~ <15> The method for producing bisphenol according to any one of the preceding claims, wherein the decomposition step and a step of preparing an adsorbed purified liquid are provided before the adsorption purification step, wherein in the step of preparing an adsorbed purified liquid, the adsorbed purified liquid is prepared from a decomposition liquid containing bisphenol obtained in the decomposition step.

[0039] <17> According to the aforementioned <8> ~ <15> The method for producing bisphenol according to any one of the preceding claims, wherein the decomposition step and the concentration step are provided before the adsorption purification step, wherein in the concentration step, the decomposition liquid containing bisphenol obtained by the decomposition step is concentrated by distillation to prepare an alkaline concentrated liquid, and the adsorption purification step is a step of bringing the concentrated liquid into contact with the adsorbent to obtain the adsorption purified liquid, and the solution removed by the concentration step is supplied to the decomposition step for reuse.

[0040] <18> According to the aforementioned <8> ~ <15> The method for producing bisphenol according to any one of the preceding claims, wherein the decomposition step, the coarse crystallization step and the redissolution step are provided before the adsorption purification step, wherein in the coarse crystallization step, the decomposition liquid containing bisphenol obtained by the decomposition step or the concentrated liquid obtained by concentrating the decomposition liquid is crystallized to separate the solid and liquid into a solid component containing bisphenol and a coarse crystallization mother liquor to obtain a solid component containing bisphenol, and in the redissolution step, the solid component containing bisphenol is redissolved to prepare an alkaline redissolution liquid, the adsorption purification step is a step of bringing the redissolution liquid into contact with the adsorbent to obtain the adsorption purified liquid, and the coarse crystallization mother liquor obtained by solid-liquid separation in the coarse crystallization step is supplied to the decomposition step to be reused.

[0041] <19> According to the aforementioned <1> ~ <18> The method for producing bisphenol described in any one of the above claims comprises a water washing step and a crystallization step. In the water washing step, the adsorption purification liquid is mixed with water and then phase-separated into an organic phase containing bisphenol and an aqueous phase. The aqueous phase is removed to obtain the organic phase. In the crystallization step, bisphenol is precipitated from the organic phase obtained by the water washing step. In the production method, the water washing step is repeatedly performed until the conductivity of the removed aqueous phase becomes 10 μS / cm or less, and then the crystallization step is performed.

[0042] <20> According to the aforementioned <1> ~ <18> The method for producing bisphenol described in any one of the above further comprises a bisphenol synthesis step of obtaining the bisphenol from a ketone or an aldehyde and an aromatic monohydric alcohol, wherein the bisphenol synthesis step comprises the following steps A0 to D0:

[0043] The adsorption purification liquid is supplied to any one or more of the following steps A0 to D0.

[0044] Step A0: a step of subjecting the ketone or aldehyde to dehydration condensation with the aromatic monohydric alcohol in the presence of an acid catalyst to obtain a reaction solution containing the bisphenol;

[0045] Step B0: a step of removing the unreacted ketone or aldehyde and water from the reaction solution obtained in the step A0 to obtain a concentrated solution;

[0046] Step C0: a step of crystallizing the concentrated liquid obtained in the above step B0, and subjecting the obtained slurry liquid to solid-liquid separation to separate into a mother liquid and a filter cake;

[0047] Step D0: A step of purifying the filter cake obtained in the step C0 to obtain the bisphenol.

[0048] <21> According to the aforementioned <1> ~ <20> The method for producing a bisphenol according to any one of the preceding claims, wherein the bisphenol is 2,2-bis(4-hydroxyphenyl)propane.

[0049] <22> According to the aforementioned <21> The method for producing bisphenol further comprises a bisphenol A synthesis step including the following steps A1 to G1, wherein the adsorption purified liquid is supplied to one or more of the following steps A1 to G1.

[0050] Step A1: a step of subjecting acetone and phenol to dehydration condensation in the presence of an acid catalyst to obtain a reaction solution containing bisphenol A;

[0051] Step B1: a step of distilling off unreacted acetone and water from the reaction liquid obtained in the above-mentioned step A1 to obtain a concentrated liquid;

[0052] Step C1: a step of crystallizing the concentrated liquid obtained in the above step B1, and subjecting the obtained slurry liquid to solid-liquid separation to separate into a mother liquid and a filter cake;

[0053] Step D1: a step of purifying the filter cake obtained in the above step C1 to obtain bisphenol A;

[0054] Step E1: a step of circulating a part of the mother liquid obtained in the above step C1 and supplying it to the above step A1;

[0055] Step F1: a step of decomposing bisphenol A in the mother liquor obtained in the above step C1 into phenol and isopropenylphenol under alkaline conditions, and then re-bonding phenol and isopropenylphenol to generate bisphenol A, thereby obtaining a solution containing bisphenol A;

[0056] Step G1: A step of supplying the solution obtained in the step F1 to the step A1.

[0057] <23> A method for producing a polycarbonate resin comprises the following steps: <1> ~ <22> A step of obtaining bisphenol by the method for producing bisphenol described in any one of the preceding claims; and a step of producing a polycarbonate resin using a bisphenol raw material containing the obtained bisphenol.

[0058] Effects of the Invention

[0059] According to the present invention, a method for producing bisphenol that can obtain bisphenol having excellent color tone can be provided. In addition, a method for producing a polycarbonate resin using the bisphenol as a raw material can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] Figure 1 This is a flow chart showing an example of the method for producing bisphenol of the present invention.

[0061] Figure 2 This is a flow chart showing an example of the method for producing bisphenol of the present invention.

[0062] Figure 3 This is a flow chart showing an example of the method for producing bisphenol of the present invention.

[0063] Figure 4 This is a flow chart showing an example of the method for producing bisphenol of the present invention.

[0064] Figure 5 This is a flow chart showing an example of the method for producing bisphenol of the present invention. DETAILED DESCRIPTION

[0065] Hereinafter, the embodiments of the present invention will be described in detail, but the description of the following technical features is an example of the embodiments of the present invention, and the present invention is not limited to the following description as long as it does not exceed its main purpose. It should be noted that when the expression "to" is used in this specification, it is used in the form of an expression including the numerical values ​​or physical property values ​​before and after it.

[0066] <Method for producing bisphenol>

[0067] The present invention relates to a method for producing bisphenol (hereinafter sometimes referred to as "the method for producing bisphenol of the present invention"), which comprises the following adsorption purification step: bringing an adsorbed purified liquid containing bisphenol and an organic solvent into contact with an adsorbent material, purifying the adsorbed purified liquid to obtain an adsorbed purified liquid, wherein the adsorbed purified liquid is alkaline.

[0068] Thus, by treating and purifying the alkaline adsorbed purified liquid containing bisphenol and an organic solvent with an adsorbent, bisphenol having excellent color tone can be obtained. The obtained bisphenol can be used to obtain a polycarbonate resin having a desired molecular weight and high polymerization activity and excellent color tone.

[0069] The method for producing bisphenol of the present invention comprises an adsorption purification step and a bisphenol recovery step. In the adsorption purification step, an adsorbed purified liquid containing bisphenol and an organic solvent is brought into contact with an adsorbent material to purify the adsorbed purified liquid to obtain an adsorbed purified liquid. In the bisphenol recovery step, bisphenol is recovered from the adsorbed purified liquid.

[0070] [Adsorption purification process]

[0071] The adsorption purification step is a step of bringing the adsorbed purified liquid containing bisphenol and an organic solvent into contact with an adsorbent to purify the adsorbed purified liquid to obtain an adsorbed purified liquid. By bringing the adsorbed purified liquid containing bisphenol and an organic solvent into contact with the adsorbent, coloring components and the like that may deteriorate the color tone of bisphenol in the adsorbed purified liquid can be removed efficiently.

[0072] In addition, as described later, the adsorbed purified liquid can also be prepared by undergoing a decomposition process in which the raw material resin as a polycarbonate resin and / or an epoxy resin is chemically decomposed. In this case, sometimes additives such as light diffusion materials, ultraviolet absorbers, and colorants contained in the decomposition raw materials are mixed into the adsorbed purified liquid, but these components can also be efficiently removed by performing an adsorption purification process. In addition, by performing an adsorption purification process, components such as antioxidants, flame retardants, and release agents can also be removed to a certain extent. Furthermore, the catalyst used when the raw material resin is chemically decomposed can also be efficiently removed, which can suppress the deterioration of the color tone of bisphenol and reduce the amount of wastewater in the bisphenol recovery process.

[0073] (Bisphenol)

[0074] Bisphenol is generally a compound represented by the following general formula (1).

[0075]

[0076] R 1 ~R 4 Each independently includes a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, and 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 isopropyl group, an n-butyl group, an isobutyl group, a tert-butyl group, an n-pentyl group, an isopentyl 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 isopropoxy group, an n-butoxy group, an isobutoxy group, a tert-butoxy group, an n-pentyl group, an isopentyl 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 cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, a cyclododecyl group, a benzyl group, a phenyl group, a tolyl group, and a 2,6-dimethylphenyl group may be mentioned.

[0077] R 5 and R 6Each independently includes a hydrogen atom, an alkyl group, an alkoxy group, and an aryl group. For example, a hydrogen atom, a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a tert-butyl group, an n-pentyl group, an isopentyl group, an n-hexyl group, an n-heptyl group, an n-octyl group, a 2-ethylhexyl 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 isopropoxy group, an n-butoxy group, an isobutoxy group, a tert-butoxy group, an n-pentyloxy group, an isopentyloxy group, an n-hexyloxy group, an n-heptyloxy group, an n-octyloxy group, an n-nonyloxy group, an n-decyloxy group, an n-undecyloxy group, an n-dodecyloxy group, a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, a cyclododecyl group, a benzyl group, a phenyl group, a tolyl group, and a 2,6-dimethylphenyl group may be mentioned.

[0078] R 5 With R 6 The two groups may be bonded or cross-linked to form a cycloalkylene group, a fluorenylene group (fluorene-9,9-diyl), a xanthene group (xanthene-9,9-diyl), a thioxanthene group (thioxanthene-9,9-diyl), etc. Examples of the cycloalkylene group include a cyclopropylene group, a cyclobutylene group, a cyclopentylene group, a cyclohexylene group, a 3,3,5-trimethylcyclohexylene group, a cycloheptylene group, a cyclooctylene group, a cyclononylene group, a cyclodecylene group, a cycloundecylene group, and a cyclododecylene group.

[0079] Specific examples of the bisphenol represented by the general formula (1) 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 1,1-bis(4-hydroxy-3-methylphenyl)cyclohexane. Pentane, 2,2-bis(4-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, 4,4-bis(4-hydroxy-3-methylphenyl)heptane, etc., but are not limited to these.

[0080] Among them, the bisphenol contained in the adsorbed purified liquid is preferably any one 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, and particularly preferably 2,2-bis(4-hydroxyphenyl)propane (hereinafter referred to as "BPA" or "bisphenol A").

[0081] Bisphenol can be produced by decomposing a polycarbonate resin or an epoxy resin in the presence of a catalyst, or by condensing a ketone or an aldehyde with an aromatic monohydric alcohol in the presence of an acid catalyst.

[0082] (Adsorbed purified liquid)

[0083] The adsorbed purified liquid in the present invention contains bisphenol and an organic solvent and is alkaline. The alkaline nature of the adsorbed purified liquid means that the pH of the adsorbed purified liquid is greater than 7, preferably greater than 7.1. The pH of the adsorbed purified liquid can be determined by, for example, sampling the adsorbed purified liquid or a portion thereof, adding an organic solvent and / or water thereto, stirring and standing the sample to separate the sample into an organic phase and an aqueous phase, and then measuring the pH of the aqueous phase. If the pH of the aqueous phase at this time is greater than 7, it can be determined that the adsorbed purified liquid is alkaline. In addition, if the composition is such that pH measurement can be performed, the pH of the adsorbed purified liquid can be directly measured.

[0084] The pH of the aqueous phase obtained by sampling the adsorbed purified liquid or a portion thereof, adding an equal amount of water to the sample, stirring, and standing to separate the two phases is preferably 7.1 or higher, more preferably 7.2 or higher. Alternatively, the pH may be 8.5 or higher.

[0085] Regarding the adsorbed purified liquid, when the solution containing bisphenol and an organic solvent is alkaline, it can be used as the adsorbed purified liquid as it is. In addition, when the solution containing bisphenol and an organic solvent is not alkaline, it can be used as the adsorbed purified liquid by adjusting it to alkaline. As the solution containing bisphenol and an organic solvent, a solution obtained by dissolving low-purity bisphenol in an organic solvent, a solution obtained by performing a bisphenol production reaction (for example, chemical decomposition of a polycarbonate resin in the presence of an organic solvent), etc. can be used.

[0086] As a method for preparing an alkaline adsorbed purified solution, there is a method of adding an alkaline compound to a solution containing bisphenol and an organic solvent. Specifically, the alkaline compound includes alkaline inorganic salts such as sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate, etc.; aliphatic amines such as ammonia, methylamine, triethylamine, etc.; aromatic amines such as aniline, toluidine, etc.; heterocyclic amines such as pyrrolidine and imidazole, etc. These alkaline compounds may be used alone or in combination of two or more. In addition, these alkaline compounds may be supplied in the form of aqueous solutions.

[0087] In order to more efficiently adsorb and remove the coloring components mixed in bisphenol, it is preferred that the adsorbed purified liquid is in a state where bisphenol is completely dissolved in the organic solvent (in a state where it is a transparent solution when viewed visually) when it comes into contact with the adsorbent.

[0088] The organic solvent contained in the adsorbed purified liquid can be any solvent as long as it can dissolve bisphenol, and can be aromatic hydrocarbons, aromatic monohydric alcohols, halogen solvents, dialkyl carbonates, etc. Among them, it is preferred to contain at least one selected from the group consisting of benzene, toluene, xylene, phenol, cresol, dichloromethane, dimethyl carbonate, and diethyl carbonate.

[0089] If the amount of organic solvent contained in the adsorbed purified liquid is small, the liquid viscosity becomes higher in proportion to the concentration of bisphenol. If the liquid viscosity is high, bisphenol may precipitate and fix during the contact with the adsorbent. In addition, when contacting with the adsorbent by the diafiltration method described later, there is a concern that the pressure difference is large and the device is damaged. Therefore, the content of the organic solvent in the adsorbed purified liquid is preferably 20% by mass or more. The content of the organic solvent in the adsorbed purified liquid 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, etc.

[0090] The adsorbed purified liquid preferably contains as little water as possible. There is a concern that the adsorption capacity may be reduced and the filterability may be deteriorated due to swelling caused by the adsorption of water molecules by the adsorbent. Therefore, the water content of the adsorbed purified liquid is preferably 10% by mass or less, more preferably 5% by mass or less, and even more preferably 1% by mass or less.

[0091] Examples of methods for reducing the water content of the adsorbed purified liquid include distillation, membrane separation, adsorption using a dehydrating agent, etc. Alternatively, a hydrophobic solvent that is not miscible with water may be used.

[0092] The adsorbed purified liquid may contain a bisphenol analogue having the same bisphenol skeleton as the bisphenol contained in the liquid phase and having a structure in which at least two carbon atoms on the benzene ring constituting the bisphenol skeleton (i.e., dihydroxydiphenylmethane structure) are double-bonded with oxygen atoms. For example, as bisphenol analogues, oxides of bisphenols such as compounds having a hydroxybenzoquinone structure obtained by oxidation of at least one hydroxyphenyl structure constituting the bisphenol skeleton can be cited. Such bisphenol analogues deteriorate the color tone of bisphenol, and therefore it is required to remove them. In the method for producing bisphenol of the present invention, even if the adsorbed purified liquid contains the above-mentioned bisphenol analogue, the above-mentioned bisphenol analogue can be removed by contacting it with an adsorbent, so that the purification can be shortened and simplified without excessively purifying the adsorbed purified liquid.

[0093] (Adsorbent material)

[0094] In the adsorption purification process, an adsorbent is used. The adsorbent preferably has a large specific surface area and efficiently adsorbs coloring components. In addition, it preferably has pores and adsorbs metal atoms such as sodium and potassium. As an example, activated clay, acid clay, activated carbon, and cation exchange resin can be listed. These adsorbents can be used alone or in combination. The adsorbent preferably contains any one selected from the group consisting of activated clay, acid clay, activated carbon, and cation exchange resin, and is more preferably contained as the main component (more than 50% by mass in the adsorbent). In addition, for the purpose of improving filterability, assisting dehydration, etc., general adsorbents such as molecular sieves, silica gel, alumina, Celite, zeolite, etc. can be mixed with any adsorbent selected from the group consisting of activated clay, acid clay, activated carbon, and cation exchange resin.

[0095] In the method for producing bisphenol of the present invention, when the adsorbent is brought into contact with the adsorbed purified liquid, the adsorbent may be used directly in a solid form, or the adsorbent may be mixed with a solvent and used in a slurry form. It should be noted that the adsorbent is a solid, and therefore, it is sometimes referred to as a "solid adsorbent".

[0096] (Contact method between adsorbed purified liquid and adsorbent material)

[0097] The method for bringing the adsorbed purified liquid into contact with the adsorbent is not particularly limited. As general methods, there are the following methods: a contact method in which the adsorbent is added to the adsorbed purified liquid, the adsorbent is stirred to allow sufficient contact, and then the adsorbent is removed by filtration; and a diafiltration method in which the adsorbed purified liquid is passed through a column filled with the adsorbent.

[0098] The adsorbent may be mixed with a solvent in advance and added to the adsorbed purified liquid in the form of a slurry, or may be filled into a column in the state of the slurry.

[0099] If the amount of adsorbent supplied in the contact method is too small, the coloring components may not be sufficiently adsorbed. Therefore, the amount of 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 to be treated. In addition, if the amount of adsorbent supplied is too large, the coloring components can be sufficiently adsorbed, but there is a concern that the burden of the filtration process increases and the economic efficiency deteriorates. Therefore, the amount of 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 adsorbed purified liquid.

[0100] The amount of the adsorbent filled in the column in the percolation method may be an excess of the bisphenol to be treated. If repeated use is required, the amount may be 10 times, 100 times, 1000 times, etc., of the bisphenol to be treated.

[0101] The adsorption purification step of contacting the adsorbed purified liquid with the adsorbent is preferably performed in an inert gas atmosphere. By contacting in an inert gas atmosphere represented by nitrogen or argon, the color tone of the adsorbed purified liquid (the purified adsorbed purified liquid containing bisphenol and an organic solvent) can be maintained.

[0102] The temperature at which the adsorbed purified liquid is brought into contact with the adsorbent is appropriately set depending on the type of adsorbent used. In order to more efficiently adsorb and remove the coloring components, it is preferred that the bisphenol is completely dissolved in the adsorbed purified liquid. Therefore, regarding the temperature, the solubility of the bisphenol in the adsorbed purified liquid must be considered. Therefore, the temperature at which the adsorbed purified liquid is brought into contact with the adsorbent is preferably 0°C to 200°C, more preferably 10°C to 190°C, and even more preferably 20°C to 180°C.

[0103] The time for contacting the adsorbed purified liquid with the adsorbent material varies depending on the type, amount and temperature of the adsorbent material used. If it is too short, the adsorption of the coloring component is insufficient. Therefore, it is usually sufficient to be more than 0.1 hours. If it is too long, the occupancy time of the device becomes long and the manufacturing efficiency deteriorates. Therefore, it is usually within 100 hours. In addition, when the diafiltration method is implemented, the treatment time is controlled according to the inner diameter, length and flow rate of the column. The inner diameter and length of the column are preferably of a size that has a surplus relative to the amount of bisphenol to be treated. Specifically, the inner diameter is preferably about 10 mm to 1000 mm, the length is preferably 20 mm to 3000 mm, and the flow rate is preferably in the range of 1 to 1000 mL / min.

[0104] [Bisphenol recovery process]

[0105] The method for recovering bisphenol from the adsorption purified liquid is not particularly limited, and it can be carried out by simple means such as crystallization, column chromatography, etc. One method for recovering bisphenol in the adsorption purified liquid is a method of taking out bisphenol in the form of a solid through a water washing step and a fine crystallization step, and further through a drying step as needed.

[0106] For example, the bisphenol recovery process includes a water washing process and a crystallization process. In the water washing process, the adsorption purification liquid is mixed with water and then phase-separated into an organic phase containing bisphenol and an aqueous phase. The aqueous phase is removed to obtain an organic phase. In the crystallization process, bisphenol is precipitated from the organic phase obtained by the water washing process. The water washing process can be repeatedly performed until the conductivity of the aqueous phase becomes 10 μS / cm or less, and then the crystallization process is performed.

[0107] Specifically, water is supplied to the adsorption purification liquid and stirred, and the two phases are separated into an organic phase and an aqueous phase. After confirming that the conductivity of the aqueous phase is 10 μS / cm or less, bisphenol is precipitated by crystallization. If the conductivity of the aqueous phase is less than 10 μS / cm, the thermal stability of bisphenol may be impaired, which is not preferred.

[0108] When the conductivity of the water phase exceeds 10 μS / cm, the conductivity of the water phase can be reduced by removing the water phase and then supplying water again and repeating the same operation. This operation can be repeated multiple times until the conductivity of the water phase becomes 10 μS / cm or less.

[0109] The supplied water may be distilled water, desalted water, ion exchange water, pure water, etc. For efficient washing of the adsorbed purified liquid, the conductivity of the supplied water is preferably 10 μS / cm or less, more preferably 5 μS / cm or less, and further preferably 2 μS / cm or less.

[0110] As a method for recovering bisphenol in the adsorption purified liquid, there is mentioned a method of supplying the adsorption purified liquid or the concentrate to a bisphenol synthesis step by a condensation reaction. This method includes the following steps A0 to D0.

[0111] Step A0: a step of subjecting a ketone or an aldehyde to dehydration condensation with an aromatic monohydric alcohol in the presence of an acid catalyst to obtain a reaction solution containing bisphenol;

[0112] Step B0: a step of removing the unreacted ketone or aldehyde and water from the reaction liquid obtained in step A0 by distillation to obtain a concentrated liquid;

[0113] Step C0: a step of crystallizing the concentrated liquid obtained in step B0, and subjecting the obtained slurry liquid to solid-liquid separation to separate into a mother liquid and a filter cake;

[0114] Step D0: A step of purifying the filter cake obtained in step C0 to obtain the above-mentioned bisphenol.

[0115] The adsorption purification liquid may be supplied to one of steps A0 to D0 of the exemplified bisphenol synthesis step, or may be supplied to a plurality of steps. The adsorption purification liquid is preferably supplied to one or more of steps A0, B0, and C0.

[0116] The adsorption purified liquid may be distilled and crystallized to concentrate bisphenol, and the concentrate may be supplied to one or more steps in the bisphenol synthesis step, or the concentrate may be replaced with a different solvent and then supplied to one or more steps in the bisphenol synthesis step.

[0117] By adopting a method in which the adsorption purification liquid is supplied to the bisphenol synthesis step by condensation reaction, the bisphenol in the adsorption purification liquid can be recovered together with the bisphenol produced from ketone or aldehyde and aromatic monohydric alcohol.

[0118] Specifically, the above-mentioned steps A0 to D0 are performed in a manufacturing facility for continuously synthesizing bisphenol from ketones or aldehydes and aromatic monohydric alcohols. The bisphenol in the adsorption purified liquid can be purified / recovered using such a manufacturing facility. Among them, when the adsorption purified liquid is obtained through a decomposition step of chemically decomposing a polycarbonate resin or an epoxy resin to obtain bisphenol and an adsorption purification step, a method of recovering bisphenol using the manufacturing facility is one of the suitable methods. That is, it is preferred that the adsorption purified liquid is introduced into a manufacturing facility for producing the same bisphenol as the bisphenol contained in the adsorption purified liquid by performing the above-mentioned steps A0 to D0, and the bisphenol is recovered.

[0119] The bisphenol obtained by the method for producing bisphenol of the present invention is heated and melted at 175°C for 30 minutes to obtain a molten liquid (hereinafter referred to as "molten liquid") preferably has a Hazen color (APHA) of 100 or less, and the smaller the APHA, the more preferably it is in the order of 80 or less, 70 or less, 60 or less, and 50 or less. In addition, with respect to bisphenol, the lightness (L*) of the aforementioned molten liquid is preferably 90 or more, more preferably 95 or more, and further preferably 98 or more. With respect to the bisphenol obtained by the method for producing bisphenol of the present invention, it is particularly preferred that both the Hazen color and the lightness of the aforementioned molten liquid satisfy the aforementioned numerical ranges.

[0120] [Decomposition process]

[0121] The method for producing bisphenol of the present invention preferably comprises a decomposition step of chemically decomposing a raw material resin in a decomposition raw material containing a raw material resin to obtain bisphenol before the adsorption purification step, wherein the raw material resin is a polycarbonate resin and / or an epoxy resin.

[0122] The decomposition process is a process of chemically decomposing (depolymerizing) the raw material resin as polycarbonate resin and / or epoxy resin, and as the decomposition raw material, the material containing polycarbonate resin and / or epoxy resin is used. The decomposition raw material usually contains polycarbonate resin and / or epoxy resin as the main component, and preferably uses the waste plastics such as the pre-consumer materials (sometimes also referred to as post-industrial materials) and the molded products (post-consumer materials) after the use of the leftovers, defective products, etc. produced when the polycarbonate resin and / or epoxy resin are molded. For example, as the waste plastics containing the raw material resin, the pre-consumer materials and the post-consumer materials of the molded products such as headlights, reflectors, lampshades for lighting lamps, housings, helmets, building materials, suitcases, CDs, etc. can be used. These molded products can be cut and broken into appropriate sizes for use as described later.

[0123] In addition, as a raw material for decomposition, a molded article having a part formed by components other than the raw material resin can be used. For example, as a raw material for decomposition, waste plastics (i.e., post-consumer materials and / or pre-consumer materials) having a metal layer and / or a resin layer formed by a resin (other resin) other than the raw material resin can be used. As an example, a molded article having a metal layer and / or a resin layer provided on its surface after appropriately adding additives to a polycarbonate resin and / or an epoxy resin and molding into a shape consistent with the purpose can be listed. The method for forming the metal layer and the resin layer is not particularly limited, and can be vapor deposition or coating. As the metal layer and / or the resin layer, aluminum vapor deposition film, aluminum coating film, resin coating film, etc. can be listed.

[0124] The decomposition raw material may include other resins and low molecular weight compounds other than polycarbonate resin and epoxy resin. For example, as a decomposition raw material, a resin composition containing polycarbonate resin and / or epoxy resin and containing microparticles and / or polar low molecular weight compounds can be used. The microparticles and polar low molecular weight compounds contained in the decomposition raw material are derived from additives, deterioration components caused by the use of molded products, etc. The average particle size of the microparticles is about 1nm to 200μm. The shape of the microparticles is spherical, needle-shaped, fibrous, plate-shaped, etc., and there is no particular limitation. The microparticles are mostly used as light diffusion materials and colorants. Specifically, silicone particles, acrylic particles, carbon black, titanium oxide, etc. can be listed. Polar low molecular weight compounds are compounds having polar groups and a molecular weight of about 200 to 1000. Bisphenol oxides having a quinone skeleton, compounds used as ultraviolet absorbers or colorants, triphenylphosphine, etc. can be listed.

[0125] The molded articles containing polycarbonate resin and / or epoxy resin are usually subjected to the addition of additives such as light diffusers, ultraviolet absorbers, colorants, antioxidants, flame retardants, and mold release agents, surface processing by hard coating or metal coating, etc. according to their uses. Such molded articles can be used as raw materials for decomposition.

[0126] For example, as a raw material for decomposition, a resin composition containing polycarbonate resin and / or epoxy resin and containing one or more additives selected from the group consisting of light diffusion materials, ultraviolet absorbers, colorants, antioxidants, flame retardants and release agents can be used. As light diffusion materials, organic fillers such as silicone particles and acrylic particles can be listed; inorganic fillers such as titanium dioxide, aluminum oxide, zinc oxide, zinc sulfide, barium sulfate, talc, calcium carbonate, and silicon dioxide can be listed. As ultraviolet absorbers, organic compounds with a molecular weight of about 200 to 1000 and ultraviolet absorption ability can be listed. For example, as ultraviolet absorbers, organic compounds with aromatic rings and / or heterocyclic rings can be listed, and specifically, triazine compounds, benzophenone compounds, benzotriazole compounds, phenyl salicylate compounds, phenyl benzoate compounds, etc. can be listed. Examples of colorants include inorganic pigments, organic pigments, and organic dyes. Specifically, examples include titanium oxide, carbon black, phthalocyanine compounds, azo compounds, quinacridone compounds, perylene compounds, anthraquinone compounds, and diketopyrrolopyrrole compounds. Examples of antioxidants include phenolic antioxidants and phosphoric acid antioxidants. Examples of flame retardants include phosphorus flame retardants, silicone flame retardants, and inorganic flame retardants such as metal hydroxides and metal oxides. Examples of release agents include fatty acid esters and polysiloxane silicone oils.

[0127] In addition, as the decomposition raw material, a material having a value obtained by multiplying the Hazen color of a dichloromethane solution of a 10% by mass raw material for decomposition by 10 (hereinafter referred to as "dichloromethane dissolved color of the decomposition raw material") of 200 or more, and a material having a lightness (L*) of a dichloromethane solution of a 10% by mass raw material for decomposition of 80 or less can be used. Such materials include post-consumer materials that have deteriorated due to use; pre-consumer materials and post-consumer materials containing additives insoluble in dichloromethane, etc. If such a material is dissolved in dichloromethane, the solution becomes yellow or turbid, and therefore, the dichloromethane dissolved color becomes larger or the lightness of the dichloromethane solution becomes lower. According to the bisphenol production method of the present invention, when the dichloromethane dissolved color of the decomposition raw material is 200 or more, bisphenol having a Hazen color of a molten liquid of bisphenol of 100 or less can be produced. Furthermore, when the brightness of a 10 mass % dichloromethane solution of the decomposition raw material is 80 or less, it is possible to produce bisphenol having a brightness of 90 or more in a melt of bisphenol.

[0128] The decomposition liquid containing bisphenol obtained in the decomposition step may be directly supplied to the adsorption purification step. Alternatively, the decomposition liquid may be used to prepare an adsorbed purified liquid to be supplied to the adsorption purification step, and the adsorbed purified liquid may be supplied to the adsorption purification step.

[0129] When the decomposition raw material contains other resins, additives, etc., these components may not dissolve and remain as insoluble components depending on the solvent used in the decomposition process. Therefore, when waste plastics (pre-consumer materials and / or post-consumer materials) are used as the decomposition raw material, it is preferred that the decomposition liquid is filtered after the decomposition process and used in the adsorption purification process or the process of preparing the adsorbed purified liquid for the adsorption purification process.

[0130] Below, with Figure 1 to Figure 5 Taking the method for producing bisphenol of the present invention having a decomposition step as an example, the following will be described in detail.

[0131] <Method for producing bisphenol (1)>

[0132] Figure 1 The method (1) for producing bisphenol shown has the following steps: a polycarbonate resin decomposition step (PC decomposition step), which chemically decomposes the polycarbonate resin to obtain a decomposition liquid containing bisphenol; an adsorbed purified liquid preparation step, which prepares an adsorbed purified liquid for use in an adsorption purification step from the decomposition liquid containing bisphenol; an adsorption purification step, which brings the adsorbed purified liquid into contact with an adsorbent to obtain an adsorbed purified liquid; and a bisphenol recovery step (BP recovery step), which recovers bisphenol from the adsorbed purified liquid.

[0133] [Polycarbonate resin decomposition process (PC decomposition process)]

[0134] The polycarbonate resin decomposition step is a step of chemically decomposing the polycarbonate resin to obtain a decomposition liquid containing bisphenol.

[0135] (Polycarbonate resin (PC))

[0136] The polycarbonate resin comprises a polymer composition containing a carbonate bond (-OC(=O)-O-). Specifically, the polycarbonate resin used in the method for producing bisphenol of the present invention comprises a repeating unit derived from bisphenol represented by the general formula (2) (hereinafter sometimes abbreviated as "repeating unit").

[0137]

[0138] Regarding R in the general formula (2) 1 ~R 6 , and R in the above formula (1) 1 ~R 6 have the same meaning.

[0139] Among them, in the method for producing bisphenol of the present invention, it is suitable to 1 ~R 4 is a hydrogen atom, R 5 , R 6A methyl polycarbonate resin (bisphenol A type polycarbonate resin) was used as a raw material resin.

[0140] In the general formula (2), n is not particularly limited and is, for example, 2 to 1,000.

[0141] The decomposition raw material used in the PC decomposition process contains polycarbonate as a raw material resin. As the decomposition raw material, not only can polycarbonate resin be used alone, but also a composition containing a resin other than polycarbonate resin, such as a copolymer or a polymer alloy, can be used. As the composition containing a resin other than polycarbonate resin, for example, polycarbonate / polyester copolymer, polycarbonate / polyester alloy, polycarbonate / polyarylate copolymer, polycarbonate / polyarylate alloy, etc. can be listed. When using a composition containing a resin other than polycarbonate resin, a material having polycarbonate resin as the main component (containing more than 50% by mass of polycarbonate resin in the composition) can be suitably used.

[0142] In addition, the polycarbonate resin may be used by mixing two or more different polycarbonate resins. It should be noted that a polycarbonate resin alone may be simply referred to as polycarbonate.

[0143] From the viewpoint of recycling, polycarbonate resin is preferably the polycarbonate resin contained in waste plastics. Polycarbonate resin is molded into various molded products such as optical components such as headlights, lampshades for lighting, housings, helmets, building materials, suitcases, optical recording media such as CDs for use. As waste plastics comprising polycarbonate resin, it is possible to use leftovers, defective products (pre-consumer materials), used molded products (post-consumer materials) etc. when polycarbonate resin is molded into these molded products.

[0144] The method (1) for producing bisphenol can efficiently remove coloring components by the adsorption purification step, so even if post-consumer materials that may contain a large amount of coloring components are used as a raw material for decomposition, bisphenol with a good color tone can be obtained. Therefore, post-consumer materials are one of the suitable raw materials for decomposition. According to the method (1) for producing bisphenol, even if the dichloromethane dissolved color of the post-consumer materials used as the raw material for decomposition is 200 or more, bisphenol with a melt color of 100 or less can be obtained in the bisphenol recovery step.

[0145] It should be noted that the methylene chloride dissolved color of post-consumer materials refers to the value obtained by multiplying the measured value of the Hazen color of a 10% by mass methylene chloride solution of post-consumer materials by 10. The melt color of bisphenol refers to the Hazen color when bisphenol is melted at 175° C. for 30 minutes. Details are described in the Examples.

[0146] In addition, pre-consumer materials and post-consumer materials containing additives such as light diffusers, ultraviolet absorbers, colorants, antioxidants, flame retardants, and release agents are also suitable raw materials for decomposition.

[0147] Waste plastics can be appropriately used after washing, crushing, pulverizing, etc. As a method of crushing waste plastics, it is possible to use a jaw crusher, a rotary crusher to crush to a coarse crushing of less than 20 cm; a rotary crusher, a cone crusher, a mill to crush to a medium crushing of less than 1 cm; a mill to crush to less than 1 mm, etc., as long as it can be reduced to a size that can be supplied to the decomposition tank. In addition, in the case of thin plastics such as CDs and DVDs, it can be cut using a book cutter and supplied to the decomposition tank. In addition, other resins of copolymers and polymer alloys, such as the surface or back layer of a CD, can be removed in advance and used.

[0148] (Decomposition method)

[0149] Regarding the method of chemically decomposing the polycarbonate resin, various decomposition methods are known for each product derived from the carbonate unit of the obtained polycarbonate resin. For example, in the hydrolysis using water as a decomposition agent, the product derived from the carbonate unit of the polycarbonate resin is obtained in the form of carbon dioxide. In addition, phenolic decomposition using phenol as a decomposition agent, alcoholic decomposition using alcohol as a decomposition agent, aminolysis using amine as a decomposition agent, etc. can also be listed. Regardless of which decomposition method is selected, bisphenol is obtained as the main product as a product derived from the bisphenol unit.

[0150] In the polycarbonate resin decomposition step, the polycarbonate resin is preferably decomposed in the presence of one or more decomposing agents selected from the group consisting of water, aromatic monohydric alcohols, and aliphatic monohydric alcohols.

[0151] Examples of the aromatic monohydric alcohol include phenol, cresol, xylenol, etc. The aromatic monohydric alcohol can be used as a decomposing agent and a solvent.

[0152] Examples of the aliphatic monohydric alcohol include methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, tert-butanol, n-pentanol, isopentanol, n-hexanol, n-heptanol, n-octanol, n-nonanol, n-decanol, n-undecanol, and n-dodecanol.

[0153] The aliphatic monohydric alcohol is preferably an alcohol having 1 to 5 carbon atoms, and more preferably any one selected from the group consisting of methanol, ethanol and butanol.

[0154] In addition, the polycarbonate resin decomposition step may be a step of decomposing the polycarbonate resin using a solvent in the presence of a solvent, a decomposition agent, and a catalyst, since the polycarbonate resin is dissolved. Examples of the solvent include aromatic hydrocarbons such as benzene, toluene, and xylene; aromatic monohydric alcohols such as phenol, cresol, and xylenol; halogen solvents such as methylene chloride; and dialkyl carbonates such as dimethyl carbonate, diethyl carbonate, dipropyl carbonate, and dibutyl carbonate.

[0155] The solvent is not particularly limited as long as it dissolves the polycarbonate resin. In view of reuse, it is preferred to use a solvent with a boiling point of 200° C. or less. In addition, from the viewpoint of preventing undesirable reactions, it is preferred to use a stable solvent with low reactivity such as an aromatic hydrocarbon. In addition, as a solvent, phenol or alcohol that functions as a decomposition agent may be supplied in excess.

[0156] If the mass ratio of the solvent to the polycarbonate resin (mass of the solvent / mass of the polycarbonate resin) is small, the dissolution rate of the polycarbonate resin decreases, and therefore, there is a tendency for the time required to produce bisphenol to be longer. Therefore, the mass ratio is preferably 0.01 or more, more preferably 0.03 or more, and further preferably 0.05 or more. In addition, if the mass ratio is large, there is a tendency that the volume of the solvent relative to the decomposition tank increases, the amount of polycarbonate resin that can be decomposed at one time becomes smaller, and the kettle efficiency deteriorates. Therefore, the mass ratio is preferably 100 or less, more preferably 70 or less, and further preferably 50 or less.

[0157] The catalyst can be any catalyst as long as it can promote the decomposition of the polycarbonate resin, and examples thereof include alkaline catalysts such as alkali metal hydroxides, alkali metal carbonates, and alkylamines; acids. When an acid is used as a catalyst, the resulting decomposition liquid and the solid component obtained by crystallizing the decomposition liquid will be acidic, and therefore, it is usually necessary to use an alkaline compound to adjust the pH to alkaline and provide it to the adsorption purification step. On the other hand, when an alkaline catalyst is used, the resulting decomposition liquid and the solid component obtained by crystallizing the decomposition liquid will be alkaline, and therefore, even if the pH is not particularly adjusted, it can be alkaline. Therefore, the catalyst is preferably an alkaline catalyst, preferably any one selected from the group consisting of alkali metal hydroxides, alkali metal carbonates, and alkylamines.

[0158] Examples of the alkali metal hydroxide include sodium hydroxide and potassium hydroxide.

[0159] Examples of the alkali metal carbonate include sodium carbonate, sodium hydrogen carbonate, potassium carbonate, potassium hydrogen carbonate, and the like.

[0160] Examples of the alkylamine include methylamine, ethylamine, propylamine, dimethylamine, diethylamine, and trimethylamine.

[0161] Examples of the acid include hydrochloric acid, sulfuric acid, and phosphoric acid as inorganic acids, and examples of carboxylic acid and sulfonic acid as organic acids.

[0162] If the mass ratio of the catalyst to the polycarbonate resin (mass of the catalyst / mass of the polycarbonate resin) is small, the decomposition rate decreases, and therefore, there is a tendency for the decomposition time to be prolonged and the efficiency to be deteriorated. Therefore, the mass ratio is preferably 0.001 or more, more preferably 0.005 or more, and further preferably 0.01 or more. In addition, if the mass ratio is large, there is a tendency for the amount of acid and base required for neutralization to increase. Therefore, the mass ratio is preferably 50 or less, more preferably 20 or less, and further preferably 10 or less.

[0163] The reaction solution can be prepared in a manner that the polycarbonate resin is completely dissolved, preferably in a slurry-like manner in which the polycarbonate resin is dispersed. When the prepared reaction solution is in a slurry-like state, as the decomposition reaction proceeds, the polycarbonate resin is completely dissolved in the solvent, so that at the moment when the PC decomposition process ends, a uniform liquid (not a slurry-like decomposition solution) can be obtained. Even if there is residual polycarbonate resin at the moment when the PC decomposition process ends, the polycarbonate resin will be completely dissolved, and a decomposition solution that is not a slurry-like state can be obtained. It should be noted that when preparing the reaction solution, the decomposition reaction can occur simultaneously.

[0164] In the PC decomposition step, it is preferred that the polycarbonate resin is decomposed in a slurry-like reaction liquid in which the polycarbonate resin is dispersed, to obtain a decomposition liquid (a uniform liquid in which the bisphenol is dissolved) that contains bisphenol and is not in a slurry. By causing the decomposition reaction to occur while a part of the polycarbonate resin is dissolved in a solvent in a slurry state in which the polycarbonate resin is dispersed, only the dissolved polycarbonate resin participates in the reaction, thereby making it easy to control the reaction or to reduce the amount of the organic solvent, and thus further improving the manufacturing efficiency.

[0165] It should be noted that the waste plastics containing polycarbonate resins usually contain other resins and additives. When these components are insoluble in the solvent used in the PC decomposition process, they remain as insoluble components in the obtained decomposition liquid, but the polycarbonate resin and the bisphenol generated by the decomposition of the polycarbonate resin will dissolve. In this case, a decomposition liquid containing bisphenol and not in a slurry state is obtained by filtering the decomposition liquid. When using waste plastics as a raw material for decomposition, it is preferred to filter the decomposition liquid after the decomposition reaction for use.

[0166] The decomposition temperature is not particularly limited. It can be set to an appropriate temperature according to the melting point and boiling point of the raw materials used in each decomposition method. When the temperature is too low, there is a concern that the solubility of the polycarbonate resin will decrease and the decomposition liquid will solidify. Therefore, it is usually preferably carried out at 10°C or above, and more preferably at 20°C or above. When the temperature is too high, there is a possibility that the solvent, raw materials, and catalyst evaporate, and decomposition may not be carried out. Therefore, it is preferably carried out at 200°C or below, and more preferably at 180°C or below.

[0167] The reaction time can be appropriately selected according to the solubility of the polycarbonate resin, the reaction temperature, etc. When the reaction time is long, the generated bisphenol tends to decompose, so it is preferably within 30 hours, more preferably within 25 hours, and further preferably within 20 hours. In addition, when the reaction time is short, the decomposition reaction may not proceed sufficiently, so it is preferably 0.1 hours or more, more preferably 0.5 hours or more, and further preferably 1 hour or more.

[0168] [Steps for preparing the adsorbed purified solution]

[0169] The step of preparing the adsorbed purified liquid is a step of preparing the adsorbed purified liquid to be used in the adsorption purification step from the decomposition liquid containing bisphenol. In the step of preparing the adsorbed purified liquid, the decomposition liquid is used to be roughly purified by neutralization, water washing, distillation, crystallization, etc., or the pH of the decomposition liquid is appropriately adjusted to prepare the adsorbed purified liquid to be used in the adsorption purification step. Since the amount of water in the decomposition liquid can be reduced, it is preferred to distill and / or crystallize the decomposition liquid to concentrate the bisphenol in the step of preparing the adsorbed purified liquid. In addition, the amount of water in the decomposition liquid can be reduced by using membrane separation, a dehydrating agent, or a hydrophobic solvent that is not miscible with water, and these operations can be used in combination.

[0170] The adsorption purification step and the bisphenol recovery step are as described above. In the adsorption purification step, the adsorbed purified liquid obtained in the adsorbed purified liquid preparation step is brought into contact with the adsorbent material to purify the adsorbed purified liquid to obtain an adsorbed purified liquid. Next, in the bisphenol recovery step, bisphenol is recovered from the adsorbed purified liquid by crystallization or by using an existing bisphenol production facility.

[0171] <Method for producing bisphenol (2)>

[0172] Figure 2The method for producing bisphenol (2) shown has the following steps: a polycarbonate resin decomposition step (PC decomposition step), which chemically decomposes the polycarbonate resin to obtain a decomposition liquid containing bisphenol; a concentration step, which concentrates the decomposition liquid containing bisphenol by distillation to prepare an alkaline concentrated liquid; an adsorption purification step, which brings the concentrated liquid into contact with an adsorbent material to obtain an adsorption purified liquid; and a bisphenol recovery step (BP recovery step), which recovers bisphenol from the adsorption purified liquid.

[0173] In the method for producing bisphenol (2), a concentration step is performed as a preparation step of the adsorbed purified liquid in the method for producing bisphenol (1). The method for producing bisphenol (2) is the same as the method for producing bisphenol (1) except for the concentration step.

[0174] [Concentration process]

[0175] In the concentration step, the decomposition liquid containing bisphenol is distilled to remove a part of the solvent and the decomposition agent, thereby obtaining a concentrated liquid containing bisphenol. In addition, when the decomposition liquid or concentrated liquid containing bisphenol is not alkaline, an alkaline compound is mixed with the decomposition liquid or concentrated liquid containing bisphenol to adjust the pH. The obtained concentrated liquid is used as the adsorbed purified liquid. The distillation conditions can be appropriately set according to the type and amount of the solvent and decomposition agent used in the polycarbonate resin decomposition step. Preferably, the concentration in the concentration step is adjusted to a concentration range in which bisphenol in the concentrated liquid does not precipitate at the treatment temperature of the adsorption purification step.

[0176] In addition, the solution (distillate) removed in the concentration step can be recycled and reused in the polycarbonate resin decomposition step.

[0177] <Method for producing bisphenol (3)>

[0178] Figure 3 The method for producing bisphenol (3) shown has the following steps: a polycarbonate resin decomposition step (PC decomposition step), which chemically decomposes the polycarbonate resin to obtain a decomposition liquid containing bisphenol; a coarse crystallization step, which crystallizes the decomposition liquid containing bisphenol, separates the solid and liquid into a solid component containing bisphenol and a coarse crystallization mother liquor, and obtains a solid component containing bisphenol; a redissolution step, which redissolves the solid component containing bisphenol to prepare an alkaline redissolution liquid; an adsorption purification step, which brings the obtained redissolution liquid into contact with an adsorbent to obtain an adsorption purified liquid; and a bisphenol recovery step (BP recovery step), which recovers bisphenol from the adsorption purified liquid.

[0179] In the method for producing bisphenol (3), a coarse crystallization step and a redissolution step are performed as the steps for preparing the adsorbed purified liquid of the method for producing bisphenol (1). The method for producing bisphenol (3) is the same as the method for producing bisphenol (1) except for the coarse crystallization step and the redissolution step.

[0180] [Coarse crystallization process]

[0181] The coarse crystallization step is a step of crystallizing the decomposition liquid containing bisphenol, separating the solid and liquid into a solid component containing bisphenol and a coarse crystallization mother liquor, and obtaining a solid component containing bisphenol. As mentioned above, waste plastics usually contain additives, other resins, coatings and other components other than the raw material resin. Among these other components, there are also components that are more easily removed by the coarse crystallization step than by the adsorption purification step. Therefore, when waste plastics are used as a decomposition raw material, the method for producing bisphenol (3) is particularly preferred. When waste plastics are used as a decomposition raw material to obtain bisphenol with a better color tone, it is more preferred to decompose the polycarbonate resin in the PC decomposition step and then filter it, and use the bisphenol decomposition liquid obtained thereby to perform the coarse crystallization step.

[0182] In the coarse crystallization step, the decomposition liquid obtained in the polycarbonate resin decomposition step is cooled to obtain a slurry in which bisphenol is precipitated. The slurry is subjected to solid-liquid separation to separate the bisphenol-containing solid content and the coarse crystallization mother liquid.

[0183] The crude crystallization step may be performed by distilling the decomposition liquid to remove at least a part of the decomposition agent and the solvent, and concentrating the bisphenol, and then using the concentrated liquid.

[0184] Since the coarse crystallization mother liquid subjected to solid-liquid separation in the coarse crystallization step contains the decomposition agent and the solvent, the mother liquid can be recycled to the polycarbonate resin decomposition step and reused for decomposition of the polycarbonate resin.

[0185] [Redissolution process]

[0186] The re-dissolution step is a step of re-dissolving the solid component containing bisphenol to prepare an alkaline re-dissolved solution. The obtained re-dissolved solution is used as the adsorbed purified solution.

[0187] As a method for preparing a re-dissolved liquid, there can be cited, for example, a method of dissolving a solid component containing bisphenol in an organic solvent for preparing a re-dissolved liquid. If the pH of the re-dissolved liquid when dissolved in an organic solvent is alkaline, it can be used directly. In the case where the pH of the re-dissolved liquid is acidic, a basic compound is mixed to adjust the pH to alkaline. The organic solvent used to prepare the re-dissolved liquid is not particularly limited as long as it can dissolve bisphenol at the temperature when it contacts the adsorbent material, and solvents such as aromatic hydrocarbons, aromatic monohydric alcohols, halogen-based solvents, and dialkyl carbonates can be used. For example, as an organic solvent for preparing a re-dissolved liquid, one or more selected from the group consisting of benzene, toluene, xylene, phenol, cresol, dichloromethane, dimethyl carbonate, and diethyl carbonate can be used.

[0188] In the case where the bisphenol obtained by the PC decomposition step is bisphenol A, if a large amount of phenol is present during the coarse crystallization, adduct crystals of bisphenol A and phenol can be obtained as solid components. If the adduct crystals are heated and melted, a phenol solution containing bisphenol A is formed. Therefore, in the case where the solid component obtained in the coarse crystallization step is an adduct crystal of bisphenol A and phenol, the adduct crystals of bisphenol A and phenol are heated and melted, so that bisphenol A can be redissolved to prepare a redissolved solution. In addition, the adduct crystals of bisphenol A and phenol can be dissolved in other organic solvents such as aromatic hydrocarbons to prepare a redissolved solution.

[0189] In order to more efficiently remove the coloring components contained in the solid content containing bisphenol, the re-dissolving liquid is preferably a uniform solution in which the bisphenol is completely dissolved, rather than a slurry-like solution in which the bisphenol is dispersed.

[0190] In addition, when the re-dissolved liquid contains water, the water content in the re-dissolved liquid can be adjusted by distilling the re-dissolved liquid to remove at least a portion of the water in the re-dissolved liquid. The distillation (dehydration distillation) for distilling and removing the water in the re-dissolved liquid is not particularly limited as long as the conditions for water evaporation occur. Water can be distilled and removed by heating to about 80°C to 100°C under reduced pressure.

[0191] <Method for producing bisphenol (3a)>

[0192] Figure 4 This is an example of a flow chart showing the method (3) for producing bisphenol in more detail.

[0193] Figure 4 In the method for producing bisphenol (3a) shown, in the polycarbonate resin decomposition step, a bisphenol A type polycarbonate resin is decomposed in the presence of an aromatic monohydric alcohol and a basic catalyst or in the presence of an aromatic monohydric alcohol, a basic catalyst and water or an aliphatic monohydric alcohol to obtain a decomposition liquid containing bisphenol A (BPA).

[0194] Next, a coarse crystallization step is performed to separate the solid and liquid into a solid component containing bisphenol A and a coarse crystallization mother liquid. The coarse crystallization mother liquid is recycled in the polycarbonate resin decomposition step.

[0195] In the re-dissolving step, the solid component separated from the solid and liquid in the coarse crystallization step is dissolved in an organic solvent (e.g., an aromatic hydrocarbon) to obtain a re-dissolved solution. In addition, when the solid component is an adduct crystal of bisphenol A and phenol, the adduct crystal can be heated and melted and then appropriately dehydrated and distilled to obtain a re-dissolved solution.

[0196] In the adsorption purification step, the re-dissolved liquid is brought into contact with an adsorbent to obtain an adsorption purified liquid.

[0197] Next, a water washing step is performed to wash the adsorption purified liquid with water to obtain an organic phase containing bisphenol A. Specifically, the adsorption purified liquid is mixed with water, phase-separated into an organic phase containing bisphenol A and an aqueous phase, and the aqueous phase is removed to obtain an organic phase. In addition, water washing is repeated until the conductivity of the aqueous phase becomes 10 μS / cm or less.

[0198] In the crystallization step, the organic phase obtained in the water washing step is crystallized to precipitate bisphenol A, and then the solid and liquid are separated into bisphenol A and a crystallization mother liquor to obtain bisphenol A. Furthermore, the bisphenol A is dried as necessary. In addition, the obtained crystallization mother liquor can be recycled in the PC decomposition step and the re-dissolution step.

[0199] <Method for producing bisphenol (3b)>

[0200] Figure 5 This is another example of a flow chart showing the method (3) for producing bisphenol in more detail.

[0201] Figure 5 In the method for producing bisphenol (3b) shown, in the polycarbonate resin decomposition step, a bisphenol A type polycarbonate resin is decomposed in the presence of an aromatic monohydric alcohol and an alkaline catalyst or in the presence of an aromatic monohydric alcohol and an alkaline catalyst and water or an aliphatic monohydric alcohol to obtain a decomposition liquid containing bisphenol A (BPA).

[0202] Next, a coarse crystallization step is performed to obtain a solid component (coarse filter cake) containing bisphenol A. In the re-dissolution step, after the solid component is dissolved in phenol, dehydration distillation is appropriately performed to obtain a re-dissolved liquid. In addition, when the solid component is an adduct crystal of bisphenol A and phenol, the adduct crystal can be heated and melted, and then dehydration distillation is appropriately performed to obtain a re-dissolved liquid.

[0203] In the adsorption purification step, the re-dissolved liquid is brought into contact with an adsorbent to obtain an adsorption purified liquid.

[0204] Next, the bisphenol A in the adsorption purified liquid was recovered using a BPA production facility that continuously produced bisphenol A from phenol and acetone.

[0205] The BPA production facility carries out the steps including the following steps A1 to G1.

[0206] Step A1: a step of subjecting acetone and phenol to dehydration condensation in the presence of an acid catalyst to obtain a reaction solution containing bisphenol A;

[0207] Step B1: a step of distilling off unreacted acetone and water from the reaction liquid obtained in step A1 to obtain a concentrated liquid;

[0208] Step C1: a step of crystallizing the concentrated liquid obtained in step B1, and subjecting the obtained slurry liquid to solid-liquid separation to separate into a mother liquid and a filter cake;

[0209] Step D1: a step of purifying the filter cake obtained in step C1 to obtain bisphenol A;

[0210] Step E1: a step of circulating a part of the mother liquid obtained in step C1 and supplying it to step A1;

[0211] Step F1: a step of decomposing bisphenol A in the mother liquid obtained in step C1 into phenol and isopropenylphenol under alkaline conditions, and then re-bonding phenol and isopropenylphenol to generate bisphenol A, thereby obtaining a solution containing bisphenol A;

[0212] Step G1: A step of supplying the solution obtained in step F1 to step A.

[0213] By supplying the adsorption purified liquid to steps A1, B1, C1, E1, F1, and G1, bisphenol A in the adsorption purified liquid is purified and recovered together with bisphenol A produced by a condensation reaction of acetone and phenol in a BPA production facility.

[0214] It should be noted that, in the methods (1) to (3), (3a), and (3b) for producing bisphenol, polycarbonate resin is used as the raw material resin for description, but the polycarbonate resin decomposition step may be replaced by a decomposition step using epoxy resin or a mixture of epoxy resin and polycarbonate resin as the raw material resin. Similar to the polycarbonate resin, waste plastics containing epoxy resin may be used as a raw material for decomposition, and post-consumer materials are one of the suitable raw materials for decomposition.

[0215] Examples of the epoxy resin that can be used in the method for producing bisphenol of the present invention include epoxy resins represented by the following general formula (3).

[0216]

[0217] Regarding R in the general formula (3) 1 ~R 6 , and R in the above formula (1) 1 ~R 6 have the same meaning.

[0218] Among them, the substances that can be used in the method for producing bisphenol of the present invention are preferably 1 ~R 4 is a hydrogen atom, R 5 , R 6 A methyl epoxy resin (bisphenol A type epoxy resin) was used as a raw material resin.

[0219] As R in the general formula (3) 7 , hydrogen atoms, halogen atoms, alkyl groups, alkoxy groups, aryl groups, carboxyl groups, etc. Examples thereof include hydrogen atoms, fluoro groups, chloro groups, bromo groups, iodo groups, methyl groups, ethyl groups, n-propyl groups, isopropyl groups, n-butyl groups, isobutyl groups, tert-butyl groups, n-pentyl groups, isopentyl groups, n-hexyl groups, n-heptyl groups, n-octyl groups, n-nonyl groups, n-decyl groups, n-undecyl groups, n-dodecyl groups, methoxy groups, ethoxy groups, n-propoxy groups, isopropoxy groups, n-butoxy groups, isobutoxy groups, tert-butoxy groups, n-pentyloxy groups, isopentyloxy groups, n-hexyloxy groups, n-heptyloxy groups, n-octyloxy groups, n-nonyloxy groups, n-decyloxy groups, n-undecyloxy groups, n-dodecyloxy groups, cyclopropyl groups, cyclobutyl groups, cyclopentyl groups, cyclohexyl groups, cycloheptyl groups, cyclooctyl groups, cyclododecyl groups, benzyl groups, phenyl groups, tolyl groups, and 2,6-dimethylphenyl groups.

[0220] In the general formula (3), n is not particularly limited and is, for example, 2 to 1,000.

[0221] <Uses of bisphenol>

[0222] The bisphenol obtained by the method for producing bisphenol of the present invention (hereinafter sometimes referred to as "bisphenol of the present invention") can be used as a constituent component, curing agent, additive or precursor thereof of various thermoplastic resins such as polyether resins, polyester resins, polyarylate resins, polycarbonate resins, polyurethane resins, acrylic resins, epoxy resins, unsaturated polyester resins, phenolic resins, polybenzoxazine resins, cyanate resins, etc., which are used in various applications such as optical materials, recording materials, insulating materials, transparent materials, electronic materials, adhesive materials, and heat-resistant materials. In addition, it is also useful as a color developer for heat-sensitive recording materials, an anti-fading agent, a bactericide, an antibacterial and antifungal agent, and the like.

[0223] Among these, because good hue and good mechanical properties can be given, they are preferably used as raw materials (monomers) for thermoplastic resins and thermosetting resins, more preferably as raw materials for polycarbonate resins and epoxy resins, and further preferably as raw materials for polycarbonate resins and epoxy resins used in optical applications. Among them, they are preferably used as raw materials for manufacturing polycarbonate resins by melt polymerization. In addition, they are also preferably used as developers, and are especially more preferably used in combination with leuco dyes and color-changing temperature regulators.

[0224] <Method for producing polycarbonate resin>

[0225] The present invention relates to a method for producing a polycarbonate resin (hereinafter sometimes referred to as "the method for producing a polycarbonate resin of the present invention"), which comprises the following steps: a step of obtaining bisphenol by the method for producing bisphenol of the present invention; and a step of producing a polycarbonate resin using a bisphenol raw material containing the obtained bisphenol (the bisphenol of the present invention).

[0226] The polycarbonate resin can be produced by a method such as a transesterification reaction of a bisphenol raw material with a carbonic acid diester such as diphenyl carbonate in the presence of an alkali metal compound and / or an alkaline earth metal compound. It should be noted that the bisphenol raw material may be the bisphenol of the present invention alone, or the bisphenol of the present invention may be used in combination with a bisphenol obtained by a method other than the method for producing the bisphenol of the present invention.

[0227] The above-mentioned transesterification reaction can be carried out by appropriately selecting a known method, and an example using bisphenol A and diphenyl carbonate as raw materials is described below.

[0228] In the method for producing the polycarbonate resin, diphenyl carbonate is preferably used in excess relative to bisphenol A. The amount of diphenyl carbonate used relative to the bisphenol A is preferably more from the viewpoint of fewer terminal hydroxyl groups of the produced polycarbonate resin and excellent thermal stability of the polymer, and preferably less from the viewpoint of faster transesterification reaction and easier production of a polycarbonate resin of a desired molecular weight. Accordingly, the amount of diphenyl carbonate used relative to 1 mol of bisphenol A is usually 1.001 mol or more, preferably 1.002 mol or more, and usually 1.3 mol or less, preferably 1.2 mol or less.

[0229] As a method for supplying the raw materials, bisphenol A and diphenyl carbonate may be supplied in a solid form, but preferably one or both of them are melted and supplied in a liquid state.

[0230] When polycarbonate resin is manufactured by transesterification reaction of diphenyl carbonate and bisphenol A, transesterification catalyst is usually used. In the manufacturing method of the above-mentioned polycarbonate resin, as the transesterification catalyst, alkali metal compounds and / or alkaline earth metal compounds are preferably used. They can be used as one, or two or more can be used in any combination and ratio. In practical terms, it is desirable to use alkali metal compounds.

[0231] The amount of catalyst used relative to 1 mol of bisphenol A or diphenyl carbonate is usually 0.05 μmol or more, preferably 0.08 μmol or more, more preferably 0.10 μmol or more, and usually 100 μmol or less, preferably 50 μmol or less, more preferably 20 μmol or less. By making the amount of catalyst used within the above range, the polymerization activity required for the polycarbonate resin of the desired molecular weight can be easily obtained, and the polycarbonate resin with excellent polymer hue and excellent fluidity during molding without excessive polymer branching can be easily obtained.

[0232] In producing the polycarbonate resin by the above method, it is preferred that the above two raw materials are continuously supplied to a raw material mixing tank, and the obtained mixture and the transesterification catalyst are continuously supplied to a polymerization tank.

[0233] In the production of a polycarbonate resin by the transesterification method, generally two raw materials supplied to a raw material mixing tank are uniformly stirred and then supplied to a polymerization tank to which a catalyst is added to produce a polymer.

[0234] Example

[0235] Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. However, the present invention is not limited to the following Examples unless it exceeds the gist of the present invention.

[0236] [Raw materials and reagents]

[0237] (1) As the raw material for decomposition containing polycarbonate resin, the following raw materials were used.

[0238] Waste polycarbonate resin composition (headlight PC)

[0239] 10 kg of headlamp covers (average size: 200 mm×100 mm×5 mm; with irregularities) cut out from polycarbonate resin headlamps of general automobiles manufactured between 2005 and 2010 using a disc grinder were used.

[0240] ·Aluminum-deposited polycarbonate resin composition (Al-deposited PC)

[0241] The aluminum-deposited polycarbonate resin composition used was a polycarbonate resin "NOVAREX (registered trademark) M7022J" manufactured by Mitsubishi Chemical Engineering Plastics Co., Ltd., molded into a 60 mm×60 mm×3 mm plate, and subjected to aluminum vapor deposition processing by Kanto Optical Equipment Co., Ltd.

[0242] Polycarbonate resin composition containing light diffusion material (light diffusion material-PC), polycarbonate resin composition containing titanium oxide (TiO2-PC), polycarbonate resin composition containing carbon black (CB-PC)

[0243] The polycarbonate resin composition containing a light diffusion material, the polycarbonate resin composition containing titanium oxide, and the polycarbonate resin composition containing carbon black used the following composition: using the polycarbonate resin "NOVAREX (registered trademark) M7022J" of Mitsubishi Chemical Engineering Plastics, 0.5% by mass of silicone microparticles (KMP-590 manufactured by Shin-Etsu Chemical Co., Ltd.), titanium dioxide (reagent manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), and carbon black (manufactured by Mitsubishi Chemical Corporation) were added, respectively, relative to the polycarbonate resin, and after mixing for 20 minutes using a rotary drum, the mixture was supplied to a twin-screw extruder equipped with one vent (TEX30HSST manufactured by Nippon Steel Works, Ltd.), and kneaded under the conditions of a screw speed of 200 rpm, a discharge amount of 15 kg / hour, and a barrel temperature of 280°C. The molten resin extruded into a strand shape was quenched in a water tank and pelletized using a pelletizer to obtain a substance.

[0244] (2) Other raw materials and reagents

[0245] As for phenol, sodium bicarbonate, toluene, dodecanethiol, acetonitrile, cesium carbonate, activated clay, acid clay, and activated carbon (powder), reagents from Fujifilm Wako Pure Chemical Industries, Ltd. were used.

[0246] Diphenyl carbonate produced by Mitsubishi Chemical Corporation was used.

[0247] [Evaluation of color tone of decomposition raw materials]

[0248] (Dichloromethane solution color of decomposition raw material)

[0249] The evaluation of the dichloromethane solution color of the decomposition raw material was carried out by the following method.

[0250] ·Device: Spectrophotometric petroleum product color tester (OME7700 manufactured by Nippon Denshoku Industries)

[0251] · Apparatus: Test tube made by Nippon Rika Glass Co., Ltd. (24mm×200m / m P-24)

[0252] 2 g of the decomposition raw material was weighed into a test tube, and 18 g of dichloromethane was added to dissolve the polycarbonate resin. The Hazen color of a dichloromethane solution containing 10% by mass of the decomposition raw material was measured using the above-mentioned apparatus, and the value obtained by multiplying the measured value by 10 was taken as the dichloromethane solution color of the decomposition raw material.

[0253] (Lightness(L*))

[0254] The brightness of a 10 mass % dichloromethane solution of the decomposition raw material was evaluated by the following method.

[0255] ·Device: Spectrophotometric petroleum product color tester (OME7700 manufactured by Nippon Denshoku Industries)

[0256] · Apparatus: Test tube made by Nippon Rika Glass Co., Ltd. (24mm×200m / m P-24)

[0257] 2 g of the decomposition raw material was weighed into a test tube, and 18 g of dichloromethane was added to dissolve the polycarbonate resin. The lightness (L*) of a dichloromethane solution containing 10% by mass of the decomposition raw material was measured using the above-mentioned apparatus.

[0258] [Evaluation of color tone of bisphenol]

[0259] The color tone of the bisphenol melt was evaluated by the following method.

[0260] (Hazen Chroma(APHA))

[0261] · Equipment: Spectrophotometric petroleum product color tester (OME7700 manufactured by Nippon Denshoku Industries Co., Ltd.), aluminum block heater

[0262] · Apparatus: Test tube made by Nippon Rika Glass Co., Ltd. (24mm×200m / m P-24)

[0263] 20 g of bisphenol was weighed into a test tube, heated to 175° C. using an aluminum block heater to melt, and the Hazen chromaticity was measured using a spectroscopic petroleum product color tester when 30 minutes had passed since the start of heating.

[0264] (Lightness(L*))

[0265] · Equipment: Spectrophotometric petroleum product color tester (OME7700 manufactured by Nippon Denshoku Industries Co., Ltd.), aluminum block heater

[0266] · Apparatus: Test tube made by Nippon Rika Glass Co., Ltd. (24mm×200m / m P-24)

[0267] 20 g of bisphenol was weighed into a test tube, heated to 175° C. using an aluminum block heater to melt, and the lightness (L*) was measured 30 minutes after the start of heating using a spectrophotometric petroleum product color tester.

[0268] [Analysis of Bisphenol A]

[0269] ·Device: "LC10A" manufactured by Shimadzu Corporation

[0270] Unison UK C18 3μm 250×4.6mmI.D

[0271] Analysis temperature: 40℃

[0272] ·Eluent composition: A10% / B90% isocratic mode

[0273] Liquid A

[0274] Liquid B Acetonitrile

[0275] Analysis time: 30 minutes

[0276] [Analysis of phenol, toluene and dodecanethiol]

[0277] ·Device: GC-2014 manufactured by Shimadzu Corporation

[0278] Agilent DB-1 0.530mm×30m 1.50μm

[0279] Method: FID

[0280] Vaporization chamber temperature: 230℃

[0281] Detector temperature: 300°C

[0282] When the analysis time is 0 to 5 minutes, the column temperature is maintained at 50°C. When the analysis time is 5 to 30 minutes, the column temperature is gradually increased to 280°C. When the analysis time is 30 to 40 minutes, the column temperature is maintained at 280°C.

[0283] ·Quantitative determination: internal standard method. Biphenyl was used as the internal standard substance.

[0284] [pH measurement of adsorbed purified liquid]

[0285] · Device: pH meter pH METER ES-73 manufactured by Horiba, Ltd.

[0286] The measurement was carried out according to the following steps.

[0287] 10 g of the adsorbed purified liquid was sampled from the separable flask into a 50 mL heat-resistant bottle, 10 g of water was added, and the mixture was stirred for 5 minutes using a magnetic stirrer in a 70°C hot water bath. After the stirring was completed, the mixture was allowed to stand to separate the two phases, and the aqueous phase was sampled. After the aqueous phase was cooled to 25°C, the pH was measured using a pH meter. The measured pH was set as the pH of the adsorbed purified liquid.

[0288] [Measurement of electrical conductivity of water phase in water washing step]

[0289] · Device: Conductivity meter COND METER D-71 manufactured by Horiba, Ltd.

[0290] [Viscosity average molecular weight (Mv)]

[0291] The viscosity average molecular weight (Mv) was calculated by dissolving a polycarbonate resin in dichloromethane (concentration: 6.0 g / L) and measuring the specific viscosity (ηsp) at 20° C. using an Ubbelohde viscometer.

[0292] ηsp / C=[η](1+0.28ηsp)

[0293] [η] = 1.23 × 10 -4 Mv 0.83

[0294] [Reference example]

[0295] The dichloromethane-soluble colors of the decomposition raw materials (RM) used in Examples and Comparative Examples are shown below.

[0296] Waste polycarbonate resin composition (headlight PC): 760

[0297] Aluminum-deposited polycarbonate resin composition (Al-deposited PC): 160

[0298] Polycarbonate resin composition containing light diffusion material (light diffusion material-PC): 260

[0299] Polycarbonate resin composition containing titanium oxide (TiO2-PC): 1440

[0300] Polycarbonate resin composition containing carbon black (CB-PC): 0

[0301] The brightness of a 10 mass % dichloromethane solution of the decomposition raw material (RM) used in Examples and Comparative Examples is as follows.

[0302] Waste polycarbonate resin composition (headlight PC): 96.8

[0303] Aluminum-deposited polycarbonate resin composition (Al-deposited PC): 97.6

[0304] Polycarbonate resin composition containing light diffusion material (light diffusion material-PC): 97.7

[0305] Polycarbonate resin composition containing titanium oxide (TiO2-PC): 18.8

[0306] Polycarbonate resin composition containing carbon black (CB-PC): 60.7

[0307] [Example 1]

[0308] (Decomposition process)

[0309] In a nitrogen atmosphere, 120 g of the waste polycarbonate resin composition (the repeating unit of the polycarbonate resin is 254 g / mol, so 120 g÷254 g / mol=0.472 mol), 107 g of a sodium bicarbonate aqueous solution adjusted to 7% by mass, 360 g of phenol, and 2.4 g of dodecanethiol were added to a jacketed separable flask equipped with a Dimrot condenser, a stirring blade, and a thermometer at room temperature. The reaction liquid was in a slurry state.

[0310] Thereafter, the internal temperature was raised to 90° C. and the reaction was allowed to proceed for 4 hours while maintaining the temperature at 90° C., thereby obtaining a decomposition liquid (homogeneous solution). A portion of the decomposition liquid was subjected to composition analysis by high performance liquid chromatography, and the generation of bisphenol A was confirmed.

[0311] (Coarse crystallization process)

[0312] The obtained decomposition liquid was slowly cooled from 90°C to 10°C to obtain slurry. The obtained slurry was filtered to obtain 166g of a coarse cake (solid content) and 384g of a coarse crystallization mother liquor. 450g of warm water was sprayed on the coarse cake to wash away phenol on the surface of the crystals.

[0313] The composition analysis of a portion of the washed crude cake by high performance liquid chromatography confirmed that it was an adduct crystal in which phenol was added to bisphenol A. The composition analysis of the obtained crude crystallization mother liquor by high performance liquid chromatography and gas chromatography showed that it contained 71.5 mass% of phenol, 6.9 mass% of bisphenol A, and 0.3 mass% of dodecanethiol. The remaining 21.3 mass% was regarded as a 7 mass% sodium bicarbonate aqueous solution.

[0314] (Redissolution process)

[0315] The obtained adduct crystals were returned to a jacketed separable flask equipped with a Dimrot condenser, a stirring blade, and a thermometer, 600 g of toluene was added, and the mixture was heated to 75° C. to dissolve the adduct crystals, thereby obtaining an organic phase a1 (redissolved liquid) containing bisphenol A.

[0316] 10 g of the organic phase a1 was taken out from the separable flask into a 50 mL heat-resistant bottle, 10 g of water was added, and the mixture was stirred for 5 minutes using a magnetic stirrer in a hot water bath at 70° C., then allowed to stand and the pH of the aqueous phase was measured to find it was 8.8.

[0317] (Adsorption purification process)

[0318] 2.0 g of activated clay was added to the organic phase a1, and after stirring for 20 minutes, the activated clay was filtered to obtain an organic phase a2 (adsorption purified liquid).

[0319] (Water washing process)

[0320] The obtained organic phase a2 was returned to the separable flask again, 100 g of water was added, and after stirring for 15 minutes, it was allowed to stand for 10 minutes to separate the two phases, thereby obtaining an organic phase a3 and an aqueous phase a4. The aqueous phase a4 was taken out into a heat-resistant bottle, cooled to 25°C, and the conductivity was measured to be 46.8 μS / cm. Water was added to the organic phase a3 again, and the same operation was performed to obtain an organic phase a5 and an aqueous phase a6. The conductivity of the aqueous phase a6 was 2.8 μS / cm. The number of water washings required for the conductivity of the aqueous phase to satisfy a value of less than 10 μS / cm was 2 times, and the amount of waste water was 1.7 g relative to 1 g of the waste polycarbonate resin composition (raw material for decomposition (RM)) supplied to the decomposition step.

[0321] (Crystallization process)

[0322] Thereafter, the organic phase a5 was cooled to 10°C to obtain a slurry. The obtained slurry was filtered to obtain 80 g of a fine filter cake. The obtained fine filter cake was dried using a rotary evaporator to obtain 62 g of bisphenol A. The yield was 58 mol% (62 g ÷ 228 g / mol ÷ 0.472 × 100 = 58 mol%). The APHA of the bisphenol A melt (BPA melt) was 55.

[0323] [Example 2]

[0324] (Decomposition process)

[0325] In a nitrogen atmosphere, 120 g of waste polycarbonate resin composition (the repeating unit of polycarbonate resin is 254 g / mol, so 120 g÷254 g / mol=0.472 mol), 380 g of crude crystallization mother liquid obtained in Example 1 (containing 271.7 g of phenol, 26.2 g of BPA, 1.1 g of dodecanethiol, 80.9 g of 7% sodium bicarbonate aqueous solution), 88.3 g of phenol, 26.1 g of 7% sodium bicarbonate aqueous solution, and 1.3 g of dodecanethiol were added to a jacketed separable flask equipped with a Dimrot condenser, a stirring blade, and a thermometer at room temperature. The reaction liquid was in a slurry state.

[0326] Thereafter, the internal temperature was raised to 90° C. and the reaction was allowed to proceed for 4 hours while maintaining the temperature at 90° C., thereby obtaining a decomposition liquid (homogeneous solution). A portion of the decomposition liquid was subjected to composition analysis by high performance liquid chromatography, and the generation of bisphenol A was confirmed.

[0327] (Coarse crystallization process)

[0328] The decomposed liquid was used to carry out the same operation as in the crude crystallization step of Example 1 to obtain 197 g of a crude cake (solid content) and 382 g of a crude crystallization mother liquid. 450 g of warm water was sprayed on the crude cake to wash away phenol on the surface of the crystals.

[0329] The composition analysis of a portion of the washed crude cake by high performance liquid chromatography confirmed that it was an adduct crystal in which phenol was added to bisphenol A. The composition analysis of the obtained crude crystallization mother liquor by high performance liquid chromatography and gas chromatography showed that it contained 72.1% by mass of phenol, 6.8% by mass of bisphenol A, and 0.3% by mass of dodecanethiol. The remaining 20.8% by mass was regarded as a 7% by mass sodium bicarbonate aqueous solution.

[0330] (Redissolution process)

[0331] The adduct crystals were returned to a jacketed separable flask equipped with a Dimrot condenser, a stirring blade, and a thermometer, 600 g of toluene was added, and the mixture was heated to 75° C. to dissolve the adduct crystals, thereby obtaining an organic phase b1 (redissolved liquid) containing bisphenol A. The pH was measured by the same method as in Example 1 and found to be 8.8.

[0332] (Adsorption purification process)

[0333] 2.0 g of activated clay was added to the organic phase b1, and after stirring for 20 minutes, the activated clay was filtered to obtain an organic phase b2 (adsorption purified liquid).

[0334] (Water washing process)

[0335] The obtained organic phase b2 was returned to the separable flask again, 100 g of water was added, and after stirring for 15 minutes, it was allowed to stand for 10 minutes to separate the two phases, thereby obtaining an organic phase b3 and an aqueous phase b4. The aqueous phase b4 was taken out into a heat-resistant bottle, cooled to 25°C, and the conductivity was measured to be 59.4 μS / cm. Water was added to the organic phase b3 again, and the same operation was performed to obtain an organic phase b5 and an aqueous phase b6. The conductivity of the aqueous phase b6 was 2.5 μS / cm. The number of water washings required for the conductivity of the aqueous phase to satisfy a value of less than 10 μS / cm was 2 times, and the amount of waste water was 1.7 g relative to 1 g of the waste polycarbonate resin composition supplied to the decomposition step.

[0336] (Crystallization process)

[0337] Thereafter, the organic phase b5 was cooled to 10°C to obtain a slurry. The obtained slurry was filtered to obtain 117 g of a refined filter cake and 621 g of a refined crystallization mother liquor. The composition of the refined crystallization mother liquor was analyzed by liquid chromatography and gas chromatography, and it contained 91.1% by mass of toluene, 7.4% by mass of phenol, and 1.2% by mass of bisphenol A.

[0338] The obtained refined cake was dried by a rotary evaporator to obtain 79 g of bisphenol A. The yield was 73 mol % (79 g÷228 g / mol÷0.472×100=73 mol %). The APHA of the bisphenol A melt was 61.

[0339] 620 g of the refined crystallization mother liquor was added to a 1L distillation flask equipped with a thermometer, a distillation tube equipped with Sulzer laboratory packing, a Liebig condenser, a stirring blade and an oil bath, and the temperature was slowly raised to 110°C while stirring, and the pressure was reduced to 647 hPa by a vacuum pump, and it was distilled by single distillation. It was evaporated to a distillation rate of 92% (distillation amount 570.6 g / feeding amount 620 g×100), and 570.6 g of recovered toluene and 47.6 g of still pot residue were obtained. The composition analysis of the still pot residue using high performance liquid chromatography and gas chromatography showed that toluene was 12% by mass, phenol was 72% by mass, and bisphenol A was 16% by mass.

[0340] [Example 3]

[0341] (Decomposition process)

[0342] In a nitrogen atmosphere, 120 g of waste polycarbonate resin composition (the repeating unit of polycarbonate resin is 254 g / mol, so 120 g÷254 g / mol=0.472 mol), 380 g of crude crystallization mother liquor obtained in Example 2 (containing 274.0 g of phenol, 25.8 g of bisphenol A, 1.1 g of dodecanethiol, and 79.0 g of 7% sodium bicarbonate aqueous solution), 47.6 g of the still residue of the refined crystallization mother liquor (containing 5.6 g of toluene, 34.5 g of phenol, and 7.4 g of bisphenol A), 45.8 g of phenol, 28.0 g of 7% sodium bicarbonate aqueous solution, and 1.3 g of dodecanethiol were added to a jacketed separable flask equipped with a Dimrot condenser, a stirring blade, and a thermometer at room temperature. The reaction liquid was in a slurry state.

[0343] Thereafter, the internal temperature was raised to 90° C. and the reaction was allowed to proceed for 4 hours while maintaining the temperature at 90° C., thereby obtaining a decomposition liquid (homogeneous solution). A portion of the decomposition liquid was subjected to composition analysis by high performance liquid chromatography, and the generation of bisphenol A was confirmed.

[0344] (Coarse crystallization process)

[0345] The obtained decomposition liquid was used to carry out the same operation as the crude crystallization step of Example 1 to obtain 205 g of a crude cake (solid content) and 383 g of a crude crystallization mother liquor. 450 g of warm water was sprayed on the crude cake to wash away the phenol on the surface of the crystals. The composition analysis of a part of the washed crude cake by high performance liquid chromatography confirmed that it was an adduct crystal in which phenol was added to bisphenol A.

[0346] (Redissolution process)

[0347] The obtained adduct crystals were returned to a jacketed separable flask equipped with a Dimrot condenser, a stirring blade, and a thermometer, 567 g of the recovered toluene obtained in Example 2 and 33 g of toluene were added, and the adduct crystals were dissolved by heating to 75° C. to obtain an organic phase c1 (redissolved liquid) containing bisphenol A. The pH was measured by the same method as in Example 1, and the pH was 8.7.

[0348] (Adsorption purification process)

[0349] The organic phase c1 was mixed with 20.0 g of activated clay and 10 g of Celite, and the mixture was passed through a simple column packed in a glass filter to obtain an organic phase c2 (adsorption purified liquid).

[0350] (Water washing process)

[0351] The obtained organic phase c2 was returned to the separable flask again, 100 g of water was added, and after stirring for 15 minutes, it was allowed to stand for 10 minutes to separate the two phases, thereby obtaining an organic phase c3 and an aqueous phase c4. The aqueous phase c4 was taken out into a heat-resistant bottle, cooled to 25°C, and the conductivity was measured to be 50.8 μS / cm. Water was added to the organic phase c3 again, and the same operation was performed to obtain an organic phase c5 and an aqueous phase c6. The conductivity of the aqueous phase c6 was 3.2 μS / cm. The number of water washings required for the conductivity of the aqueous phase to satisfy a value of less than 10 μS / cm was 2 times, and the amount of waste water was 1.7 g relative to 1 g of the waste polycarbonate resin composition supplied to the decomposition step.

[0352] (Crystallization process)

[0353] Thereafter, the temperature of the organic phase c5 was lowered to 10° C. to obtain a slurry. The obtained slurry was filtered to obtain 121 g of a refined filter cake and 620 g of a refined crystallization mother liquor.

[0354] The obtained refined cake was dried by a rotary evaporator to obtain 82 g of bisphenol A. The yield was 76 mol% (82 g÷228 g / mol÷0.472×100=76 mol%). The APHA of the bisphenol A melt was 60.

[0355] [Comparative Example 1]

[0356] (Decomposition process and coarse crystallization process)

[0357] The same operation as the decomposition step and the coarse crystallization step of Example 1 was performed to obtain 160 g of coarse filter cake (solid content) and 382 g of coarse crystallization mother liquor. 450 g of warm water was sprayed on the coarse filter cake to wash away the phenol on the surface of the crystal. The composition analysis of a part of the coarse filter cake after washing by high performance liquid chromatography confirmed that it was an adduct crystal with phenol added to bisphenol A. The composition analysis of the obtained coarse crystallization mother liquor by high performance liquid chromatography and gas chromatography showed that it contained 70.6% by mass of phenol, 6.6% by mass of bisphenol A, and 0.3% by mass of dodecanethiol. The remaining 22.5% by mass was regarded as a 7% by mass sodium bicarbonate aqueous solution.

[0358] (Redissolution process)

[0359] The adduct crystals were returned to a jacketed separable flask equipped with a Dimrot condenser, a stirring blade, and a thermometer, 600 g of toluene was added, and the mixture was heated to 75° C. to dissolve the adduct crystals, thereby obtaining an organic phase d1 (redissolved liquid) containing bisphenol A. The pH was measured by the same method as in Example 1 and found to be 8.8.

[0360] (Water washing process)

[0361] The obtained organic phase d1 is returned to the separable flask again, and the same operation as the water washing step in Example 1 is carried out to obtain an organic phase d2 and an aqueous phase d3. The aqueous phase d3 is taken out into a heat-resistant bottle, cooled to 25°C, and the conductivity is measured to be 450μS / cm. Water is added to the organic phase d2 again, and the same operation is repeated to obtain an organic phase d4. The final conductivity of the aqueous phase is 5.3μS / cm. The number of water washings required for the conductivity of the aqueous phase to meet the requirement of less than 10μS / cm is 5 times, and the amount of waste water is 4.2g relative to 1g of the waste polycarbonate resin composition supplied to the decomposition step.

[0362] (Crystallization process)

[0363] Thereafter, the temperature of the organic phase d4 was lowered to 10° C. to obtain a slurry. The obtained slurry was filtered to obtain 105 g of a refined filter cake and 623 g of a refined crystallization mother liquor.

[0364] The obtained refined cake was dried by 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%). The APHA of the bisphenol A melt was 210.

[0365] [Comparative Example 2]

[0366] (Decomposition process)

[0367] In a nitrogen atmosphere, 120 g of waste polycarbonate resin composition (the repeating unit of polycarbonate resin is 254 g / mol, so 120 g÷254 g / mol=0.472 mol), 380 g of coarse crystallization mother liquid obtained in Comparative Example 1 (containing 268.3 g of phenol, 25.1 g of BPA, 1.1 g of dodecanethiol, 85.5 g of 7% sodium bicarbonate aqueous solution), 91.7 g of phenol, 21.5 g of 7% sodium bicarbonate aqueous solution, and 1.3 g of dodecanethiol were added to a jacketed separable flask equipped with a Dimrot condenser, a stirring blade, and a thermometer at room temperature. The reaction liquid was in a slurry state.

[0368] Thereafter, the internal temperature was raised to 90° C. and the reaction was allowed to proceed for 4 hours while maintaining the temperature at 90° C., thereby obtaining a decomposition liquid (homogeneous solution). A portion of the decomposition liquid was subjected to composition analysis by high performance liquid chromatography, and the generation of bisphenol A was confirmed.

[0369] (Coarse crystallization process)

[0370] The obtained decomposition liquid was used to carry out the same operation as the crude crystallization step of Example 1 to obtain 195 g of a crude cake (solid content) and 383 g of a crude crystallization mother liquor. 450 g of warm water was sprayed on the crude cake to wash away the phenol on the surface of the crystals. The composition analysis of a part of the washed crude cake by high performance liquid chromatography confirmed that it was an adduct crystal in which phenol was added to bisphenol A.

[0371] (Redissolution process)

[0372] The adduct crystals were returned to a jacketed separable flask equipped with a Dimrot condenser, a stirring blade, and a thermometer, 600 g of toluene was added, and the mixture was heated to 75° C. to dissolve the adduct crystals, thereby obtaining an organic phase e1 (redissolved liquid) containing bisphenol A. The pH was measured by the same method as in Example 1 and found to be 8.7.

[0373] (Water washing process)

[0374] The obtained organic phase e1 was returned to the separable flask again, and the same operation as the water washing step in Example 1 was performed to obtain an organic phase e2 and an aqueous phase e3. The aqueous phase e3 was taken out into a heat-resistant bottle, cooled to 25°C, and the conductivity was measured to be 472μS / cm. Water was added to the organic phase e2 again, and the same operation was repeated to obtain an organic phase e4. The final conductivity of the aqueous phase was 6.0μS / cm. The number of water washings required for the conductivity of the aqueous phase to meet 10μS / cm or less was 5 times, and the amount of waste water was 4.2g relative to 1g of the waste polycarbonate resin composition supplied to the decomposition step.

[0375] (Crystallization process)

[0376] Thereafter, the temperature of the organic phase e4 was lowered to 10° C. to obtain a slurry. The obtained slurry was filtered to obtain 119 g of a refined filter cake and 621 g of a refined crystallization mother liquor.

[0377] The obtained refined cake was dried by a rotary evaporator to obtain 79 g of bisphenol A. The yield was 73 mol % (79 g÷228 g / mol÷0.472×100=73 mol %). The APHA of the bisphenol A melt was 500.

[0378] [Comparative Example 3]

[0379] (Decomposition process)

[0380] The same operation as the decomposition step of Example 1 was carried out, and after 4 hours of reaction, a decomposition liquid (homogeneous solution) was obtained. 10 g of 70% sulfuric acid aqueous solution was added to the decomposition liquid, and after stirring for 15 minutes, the two phases were separated, and the aqueous phase was removed to obtain an organic phase f1.

[0381] (Coarse crystallization process)

[0382] The obtained organic phase f1 was slowly cooled from 90°C to 10°C to obtain a slurry liquid. The obtained slurry was filtered to obtain 122g of a coarse filter cake (solid content) and 381g of a coarse crystallization mother liquor. 450g of warm water was sprayed on the coarse filter cake to wash away the phenol on the surface of the crystal. The composition analysis of a part of the washed coarse filter cake by high performance liquid chromatography confirmed that it was an adduct crystal with phenol added to bisphenol A.

[0383] (Redissolution process)

[0384] The obtained adduct crystals were returned to a jacketed separable flask equipped with a Dimrot condenser, a stirring blade, and a thermometer, 600 g of toluene was added, and the mixture was heated to 75° C. to dissolve the adduct crystals, thereby obtaining an organic phase f2 (redissolved liquid) containing bisphenol A.

[0385] 10 g of the organic phase f2 was taken out from the separable flask into a 50 mL heat-resistant bottle, 10 g of water was added, and the mixture was stirred for 5 minutes using a magnetic stirrer in a hot water bath at 70° C., then allowed to stand and the pH of the aqueous phase was measured to find it was 3.3.

[0386] (Adsorption purification process)

[0387] 2.0 g of activated clay was added to the organic phase f2, and after stirring for 20 minutes, the activated clay was filtered to obtain an organic phase f3.

[0388] (Water washing process)

[0389] The obtained organic phase f3 was returned to the separable flask again, and the same operation as the water washing step in Example 1 was performed to obtain an organic phase f4 and an aqueous phase f5. The aqueous phase f5 was taken out into a heat-resistant bottle, cooled to 25°C, and the conductivity was measured to be 790μS / cm. Water was added to the organic phase f4 again, and the same operation was repeated to obtain an organic phase f6. The final conductivity of the aqueous phase was 5.5μS / cm. The number of water washings required for the conductivity of the aqueous phase to meet the requirement of 10μS / cm or less was 4 times, and the amount of waste water was 3.3g relative to 1g of the waste polycarbonate resin composition supplied to the decomposition step.

[0390] (Crystallization process)

[0391] Thereafter, the temperature of the organic phase f6 was lowered to 10° C. to obtain a slurry. The obtained slurry was filtered to obtain 98 g of a refined filter cake and 620 g of a refined crystallization mother liquor.

[0392] The obtained refined cake was dried by a rotary evaporator to obtain 62 g of bisphenol A. The yield was 58 mol% (62 g÷228 g / mol÷0.472×100=58 mol%). The APHA of the bisphenol A melt was 64.

[0393] [Example 4]

[0394] (Decomposition process)

[0395] The same operation as the decomposition step of Example 1 was carried out to obtain a decomposition liquid (homogeneous solution) containing bisphenol A.

[0396] (Coarse crystallization process)

[0397] The decomposed liquid was used to carry out the same operation as in the crude crystallization step of Example 1 to obtain 175 g of a crude cake (solid content) and 372 g of a crude crystallization mother liquid. 450 g of warm water was sprayed on the crude cake to wash away phenol on the surface of the crystals.

[0398] Composition analysis of a portion of the washed crude cake by high performance liquid chromatography confirmed that the cake was an adduct crystal in which phenol was added to bisphenol A.

[0399] (Redissolution process)

[0400] The adduct crystals were returned to a jacketed separable flask equipped with a Dimrot condenser, a stirring blade, and a thermometer, 600 g of toluene was added, and the adduct crystals were dissolved by heating to 75° C. to obtain an organic phase g1 (redissolved liquid) containing bisphenol A. The pH was measured by the same method as in Example 1 and the pH was 8.6.

[0401] (Adsorption purification process)

[0402] The organic phase g1 was passed through a glass filter filled with 25 g of activated carbon, and filtered while slightly reducing the pressure using a vacuum pump to obtain an organic phase g2 (adsorption purified liquid).

[0403] (Water washing process)

[0404] The obtained organic phase g2 was returned to the separable flask again, 100 g of water was added, and after stirring for 15 minutes, it was allowed to stand for 10 minutes to separate the two phases, thereby obtaining an organic phase g3 and an aqueous phase g4. The aqueous phase g4 was taken out into a heat-resistant bottle, cooled to 25°C, and the conductivity was measured to be 12.3 μS / cm. Water was added to the organic phase g3 again, and the same operation was performed to obtain an organic phase g5 and an aqueous phase g6. The conductivity of the aqueous phase g6 was 4.4 μS / cm. The number of water washings required for the conductivity of the aqueous phase to satisfy a value of less than 10 μS / cm was 2 times, and the amount of waste water was 1.7 g relative to 1 g of the waste polycarbonate resin composition supplied to the decomposition step.

[0405] (Crystallization process)

[0406] Thereafter, the temperature of the organic phase g5 was lowered to 10° C. to obtain a slurry. The obtained slurry was filtered to obtain 81 g of a refined filter cake and 544 g of a refined crystallization mother liquor.

[0407] The obtained refined cake was dried by a rotary evaporator to obtain 62 g of bisphenol A. The yield was 58 mol% (62 g÷228 g / mol÷0.472×100=58 mol%). The APHA of the bisphenol A melt was 45.

[0408] The results of Examples 1 to 4 and Comparative Examples 1 to 3 are summarized in Table 1. As can be seen from Table 1, by treating the adsorbed purified liquid containing bisphenol obtained by depolymerizing a waste polycarbonate resin composition with an adsorbent, bisphenol having excellent color tone can be obtained. In addition, the amount of waste water can be reduced.

[0409] [Table 1]

[0410]

[0411] [Example 5]

[0412] Into a glass reaction tank with a content of 45 mL equipped with a stirrer and a distillation tube, 10.00 g (0.04 mol) of bisphenol A obtained in Example 1, 9.95 g (0.05 mol) of diphenyl carbonate, and 18 μL of a 400 mass ppm cesium carbonate aqueous solution were added. The glass reaction tank was depressurized to about 100 Pa and then returned to atmospheric pressure with nitrogen gas three times to replace the interior of the reaction tank with nitrogen gas. Thereafter, the reaction tank was immersed in an oil bath at 220° C. to dissolve the contents.

[0413] The rotation speed of the stirrer was set to 100 times per minute, and the pressure in the reaction vessel was reduced from 101.3 kPa to 13.3 kPa in absolute pressure over 40 minutes while distilling off phenol produced as a by-product by the oligomerization reaction of bisphenol A and diphenyl carbonate in the reaction vessel.

[0414] Next, the pressure in the reaction vessel was maintained at 13.3 kPa, and the transesterification reaction was performed for 80 minutes while further distilling off phenol.

[0415] Thereafter, while the external temperature of the reaction vessel was raised to 290° C., the pressure in the reaction vessel was reduced from 13.3 kPa to 399 Pa in absolute pressure over 40 minutes, and the distilled phenol was removed to the outside of the system.

[0416] Thereafter, the absolute pressure of the reaction tank was reduced to 30 Pa to carry out the polycondensation reaction. The polycondensation reaction was terminated when the stirrer of the reaction tank reached a predetermined stirring power. The time from heating to 290° C. to the completion of the polymerization was 120 minutes.

[0417] Next, the reaction tank was restored to an absolute pressure of 101.3 kPa with nitrogen gas, and then the pressure was increased to a gauge pressure of 0.2 MPa, and the polycarbonate resin was taken out from the reaction tank to obtain the polycarbonate resin. The viscosity average molecular weight (Mv) of the obtained polycarbonate resin was 26,300.

[0418] [Comparative Example 4]

[0419] Into a glass reaction tank with a content of 45 mL equipped with a stirrer and a distillation tube, 10.00 g (0.04 mole) of bisphenol A obtained in Comparative Example 3, 9.95 g (0.05 mole) of diphenyl carbonate, and 18 μL of a 400 mass ppm cesium carbonate aqueous solution were added. The glass reaction tank was depressurized to about 100 Pa and then returned to atmospheric pressure with nitrogen gas three times to replace the interior of the reaction tank with nitrogen gas. Thereafter, the reaction tank was immersed in an oil bath at 220° C. to dissolve the contents.

[0420] The rotation speed of the stirrer was set to 100 times per minute, and the pressure in the reaction vessel was reduced from 101.3 kPa to 13.3 kPa in absolute pressure over 40 minutes while distilling off phenol produced as a by-product by the oligomerization reaction of bisphenol A and diphenyl carbonate in the reaction vessel.

[0421] Next, the pressure in the reaction vessel was maintained at 13.3 kPa, and the transesterification reaction was performed for 80 minutes while further distilling off phenol. However, during the reaction, phenol stopped distilling off and polymerization did not proceed.

[0422] The results of Example 5 and Comparative Example 4 are summarized in Table 2.

[0423] [Table 2]

[0424]

[0425] [Example 6]

[0426] (Decomposition process)

[0427] In a nitrogen atmosphere, 199 g of the waste polycarbonate resin composition (the repeating unit of the polycarbonate resin is 254 g / mol, so 199 g÷254 g / mol=0.783 mol), 88 g of a sodium bicarbonate aqueous solution adjusted to 7% by mass, 299 g of phenol, and 2.0 g of dodecanethiol were added to a jacketed separable flask equipped with a Dimrot condenser, a stirring blade, and a thermometer at room temperature. The reaction liquid was in a slurry state.

[0428] Thereafter, the internal temperature was raised to 90° C. and the reaction was allowed to proceed for 4 hours while maintaining the temperature at 90° C., thereby obtaining a decomposition liquid (homogeneous solution). A portion of the decomposition liquid was subjected to composition analysis by high performance liquid chromatography, and the generation of bisphenol A was confirmed.

[0429] To this decomposition liquid, 5.0 g of an aqueous sulfuric acid solution adjusted to 70% by mass was supplied to partially neutralize the solution with sodium hydrogen carbonate.

[0430] The decomposition liquid was filtered under reduced pressure using circular quantitative filter paper No. 5A manufactured by ADVANTEC, thereby obtaining a clear decomposition liquid.

[0431] (Coarse crystallization process)

[0432] 100 g of desalted water was added to the filtered decomposition liquid, and the temperature was slowly lowered from 90°C to 10°C to obtain slurry. The obtained slurry was filtered to obtain 244 g of a coarse filter cake (solid content) and 341 g of a coarse crystallization mother liquor. 400 g of warm water was sprayed on the coarse filter cake to wash the coarse filter cake.

[0433] (Redissolution process)

[0434] 222 g of the obtained crude cake was returned to a jacketed separable flask equipped with a Dimrot condenser, a stirring blade, and a thermometer, 600 g of toluene was added, and the mixture was heated to 75° C. to dissolve the crude cake, thereby obtaining an organic phase h1 (redissolved liquid) containing bisphenol A. The pH was measured by the same method as in Example 1, and the pH was 7.3.

[0435] (Adsorption purification process)

[0436] The organic phase h1 obtained in the re-dissolution step was passed through a glass filter filled with 25 g of activated carbon, and filtered while slightly reducing the pressure using a vacuum pump to obtain an organic phase h2 (adsorption purified liquid).

[0437] (Water washing process)

[0438] The organic phase h2 obtained in the adsorption purification step was subjected to the same operation as the water washing step in Example 1, and was washed with water three times to obtain an organic phase h3 in order to make the conductivity of the water phase satisfy 10 μS / cm or less. The conductivity of the water phase in the third washing was 2.3 μS / cm. The amount of waste water was 1.5 g relative to 1 g of the waste polycarbonate resin composition supplied to the decomposition step.

[0439] (Crystallization process)

[0440] Thereafter, the temperature of the organic phase h3 was lowered to 10° C. to obtain a slurry, which was filtered to obtain 125 g of a refined filter cake and 692 g of a refined crystallization mother liquor.

[0441] The obtained refined cake was dried by a rotary evaporator to obtain 103 g of bisphenol A. The yield was 58 mol% (103 g÷228 g / mol÷0.783×100=58 mol%). The APHA of the bisphenol A melt was 52.

[0442] [Example 7]

[0443] (Decomposition process)

[0444] The polycarbonate resin was decomposed under the same conditions as in Example 6, to obtain a decomposition liquid, except that the decomposition raw material (RM) was changed to a polycarbonate resin composition containing a light diffusing material.

[0445] (Coarse crystallization process)

[0446] 100 g of deionized water was added to the decomposition liquid obtained in the decomposition step, and the temperature was slowly lowered from 90°C to 10°C to obtain slurry. The obtained slurry was filtered to obtain 238 g of a coarse filter cake (solid content) and 340 g of a coarse crystallization mother liquor. 400 g of warm water was sprayed on the coarse filter cake to wash the coarse filter cake.

[0447] (Redissolution process)

[0448] 210 g of the obtained crude cake was returned to a jacketed separable flask equipped with a Dimrot condenser, a stirring blade, and a thermometer, 600 g of toluene was added, and the mixture was heated to 75° C. to dissolve the crude cake, thereby obtaining an organic phase i1 (redissolved liquid) containing bisphenol A. The pH was measured by the same method as in Example 1, and the pH was 7.4.

[0449] (Adsorption purification process)

[0450] The organic phase i1 obtained in the re-dissolution step was passed through a glass filter filled with 25 g of activated carbon, and filtered while slightly reducing the pressure using a vacuum pump to obtain an organic phase i2 (adsorption purified liquid).

[0451] (Water washing process)

[0452] The obtained organic phase i2 was subjected to the same operation as the water washing step of Example 1, and was washed with water three times to make the conductivity of the water phase satisfy 10 μS / cm or less, thereby obtaining an organic phase i3. The conductivity of the water phase in the third washing was 3.1 μS / cm. The amount of waste water was 1.5 g relative to 1 g of the polycarbonate resin composition containing the light diffusion material supplied to the decomposition step.

[0453] (Crystallization process)

[0454] Thereafter, the temperature of the organic phase i3 was lowered to 10° C. to obtain a slurry. The obtained slurry was filtered to obtain 119 g of a refined filter cake and 690 g of a refined crystallization mother liquor.

[0455] The obtained refined cake was dried by a rotary evaporator to obtain 99 g of bisphenol A. The yield was 55 mol% (99 g÷228 g / mol÷0.783×100=55 mol%). The APHA of the bisphenol A melt was 25 and the L* (brightness) was 99.4.

[0456] [Example 8]

[0457] (Decomposition process)

[0458] The polycarbonate resin was decomposed under the same conditions as in Example 6, except that the decomposition raw material (RM) was changed to an aluminum-deposited polycarbonate resin composition, to obtain a decomposition liquid.

[0459] (Coarse crystallization process)

[0460] 100 g of deionized water was added to the decomposition liquid obtained in the decomposition step, and the temperature was slowly lowered from 90°C to 10°C to obtain slurry. The obtained slurry was filtered to obtain 235 g of a coarse filter cake (solid content) and 342 g of a coarse crystallization mother liquor. 400 g of warm water was sprayed on the coarse filter cake to wash the coarse filter cake.

[0461] (Redissolution process)

[0462] 213 g of the obtained crude cake was returned to a jacketed separable flask equipped with a Dimrot condenser, a stirring blade, and a thermometer, 600 g of toluene was added, and the mixture was heated to 75° C. to dissolve the crude cake, thereby obtaining an organic phase j1 (redissolved liquid) containing bisphenol A. The pH was measured by the same method as in Example 1, and the pH was 7.4.

[0463] (Adsorption purification process)

[0464] The organic phase j1 obtained in the re-dissolution step was passed through a glass filter filled with 25 g of activated carbon, and filtered while slightly reducing the pressure using a vacuum pump to obtain an organic phase j2 (adsorption purified liquid).

[0465] (Water washing process)

[0466] The obtained organic phase j2 was subjected to the same operation as the water washing step of Example 1, and was washed with water three times to make the conductivity of the water phase satisfy 10 μS / cm or less, thereby obtaining an organic phase j3. The conductivity of the water phase in the third washing was 2.8 μS / cm. The amount of waste water was 1.5 g relative to 1 g of the aluminum-deposited polycarbonate resin composition supplied to the decomposition step.

[0467] (Crystallization process)

[0468] Thereafter, the temperature of the organic phase j3 was lowered to 10° C. to obtain a slurry. The obtained slurry was filtered to obtain 123 g of a refined filter cake and 693 g of a refined crystallization mother liquor.

[0469] The obtained refined cake was dried by a rotary evaporator to obtain 101 g of bisphenol A. The yield was 57 mol% (101 g÷228 g / mol÷0.783×100=57 mol%). The APHA of the bisphenol A melt was 38.

[0470] [Example 9]

[0471] (Decomposition process)

[0472] The polycarbonate resin was decomposed under the same conditions as in Example 6, to obtain a decomposition liquid, except that the decomposition raw material (RM) was changed to a polycarbonate resin composition containing titanium oxide and the partial neutralization with 70% sulfuric acid was not performed.

[0473] (Coarse crystallization process)

[0474] 100 g of deionized water was added to the decomposition liquid obtained in the decomposition step, and the temperature was slowly lowered from 90°C to 10°C to obtain slurry. The obtained slurry was filtered to obtain 233 g of a coarse filter cake (solid content) and 344 g of a coarse crystallization mother liquor. 400 g of warm water was sprayed on the coarse filter cake to wash the coarse filter cake.

[0475] (Redissolution process)

[0476] 211 g of the obtained crude cake was returned to a jacketed separable flask equipped with a Dimrot condenser, a stirring blade, and a thermometer, 600 g of toluene was added, and the mixture was heated to 75° C. to dissolve the crude cake, thereby obtaining an organic phase k1 (redissolved liquid) containing bisphenol A. The pH was measured by the same method as in Example 1, and the pH was 8.7.

[0477] (Adsorption purification process)

[0478] The organic phase k1 obtained in the re-dissolution step was passed through a glass filter filled with 25 g of activated carbon, and filtered while slightly reducing the pressure using a vacuum pump to obtain an organic phase k2 (adsorption purified liquid).

[0479] (Water washing process)

[0480] The obtained organic phase k2 was subjected to the same operation as the water washing step of Example 1, and was washed with water three times to make the conductivity of the water phase satisfy 10 μS / cm or less, thereby obtaining an organic phase k3. The conductivity of the water phase in the third washing was 3.5 μS / cm. The amount of waste water was 1.5 g relative to 1 g of the polycarbonate resin composition containing titanium oxide supplied to the decomposition step.

[0481] (Crystallization process)

[0482] Thereafter, the temperature of the organic phase k3 was lowered to 10° C. to obtain a slurry. The obtained slurry was filtered to obtain 119 g of a refined filter cake and 694 g of a refined crystallization mother liquor.

[0483] The obtained refined cake was dried by a rotary evaporator to obtain 100 g of bisphenol A. The yield was 56 mol% (100 g÷228 g / mol÷0.783×100=56 mol%). The APHA of the bisphenol A melt was 30 and the L* (brightness) was 98.7.

[0484] [Example 10]

[0485] (Decomposition process)

[0486] The polycarbonate resin was decomposed under the same conditions as in Example 6 to obtain a decomposition liquid, except that the raw material (RM) for decomposition was changed to a polycarbonate resin composition containing carbon black and the partial neutralization with 70% sulfuric acid was not performed.

[0487] (Coarse crystallization process)

[0488] 100 g of deionized water was added to the decomposition liquid obtained in the decomposition step, and the temperature was slowly lowered from 90°C to 10°C to obtain slurry. The obtained slurry was filtered to obtain 233 g of a coarse filter cake (solid content) and 340 g of a coarse crystallization mother liquor. 400 g of warm water was sprayed on the coarse filter cake to wash the coarse filter cake.

[0489] (Redissolution process)

[0490] 210 g of the obtained crude cake was returned to a jacketed separable flask equipped with a Dimrot condenser, a stirring blade, and a thermometer, 600 g of toluene was added, and the mixture was heated to 75° C. to dissolve the crude cake, thereby obtaining an organic phase m1 (redissolved liquid) containing bisphenol A. The pH was measured by the same method as in Example 1, and the pH was 8.8.

[0491] (Adsorption purification process)

[0492] The organic phase m1 obtained in the re-dissolution step was passed through a glass filter filled with 25 g of activated carbon, and filtered while slightly reducing the pressure using a vacuum pump to obtain an organic phase m2 (adsorption purified liquid).

[0493] (Water washing process)

[0494] The obtained organic phase m2 was subjected to the same operation as the water washing step of Example 1, and was washed with water three times to make the conductivity of the water phase satisfy 10 μS / cm or less, thereby obtaining an organic phase m3. The conductivity of the water phase at the third time was 3.1 μS / cm. The amount of waste water was 1.5 g relative to 1 g of the polycarbonate resin composition containing carbon black supplied to the decomposition step.

[0495] (Crystallization process)

[0496] Thereafter, the temperature of the organic phase m3 was lowered to 10° C. to obtain a slurry. The obtained slurry was filtered to obtain 125 g of a refined filter cake and 692 g of a refined crystallization mother liquor.

[0497] The obtained refined cake was dried by a rotary evaporator to obtain 103 g of bisphenol A. The yield was 58 mol% (103 g÷228 g / mol÷0.783×100=58 mol%). The APHA of the bisphenol A melt was 36 and the L* (brightness) was 98.6.

[0498] [Comparative Example 5]

[0499] (Decomposition process)

[0500] In a nitrogen atmosphere, 120 g of waste polycarbonate resin composition (the repeating unit of polycarbonate resin is 254 g / mol, so 120 g÷254 g / mol=0.472 mol), 120 g of p-toluenesulfonic acid, 360 g of phenol, 45 g of water, and 2.4 g of dodecanethiol were added to a jacketed separable flask equipped with a Dimrot condenser, a stirring blade, and a thermometer at room temperature. The reaction liquid was in a slurry state.

[0501] Thereafter, the internal temperature was raised to 90° C. and the reaction was allowed to proceed for 4 hours while maintaining the temperature at 90° C., thereby obtaining a decomposition liquid (homogeneous solution). A portion of the decomposition liquid was subjected to composition analysis by high performance liquid chromatography, and the generation of bisphenol A was confirmed.

[0502] (Coarse crystallization process)

[0503] The obtained decomposition liquid was slowly cooled from 90°C to 10°C to obtain slurry. The obtained slurry was filtered to obtain 140 g of a coarse cake (solid content) and 391 g of a coarse crystallization mother liquor. 450 g of warm water was sprayed on the coarse cake to wash away phenol on the surface of the crystals.

[0504] Composition analysis of a portion of the washed crude cake by high performance liquid chromatography confirmed that the cake was an adduct crystal in which phenol was added to bisphenol A.

[0505] (Redissolution process)

[0506] The obtained adduct crystals were returned to a jacketed separable flask equipped with a Dimrot condenser, a stirring blade, and a thermometer, 600 g of toluene was added, and the mixture was heated to 75° C. to dissolve the adduct crystals, thereby obtaining an organic phase n1 (redissolved liquid) containing bisphenol A.

[0507] 10 g of the organic phase n1 was taken out from the separable flask into a 50 mL heat-resistant bottle, 10 g of water was added, and the mixture was stirred for 5 minutes using a magnetic stirrer in a hot water bath at 70° C., then allowed to stand and the pH of the aqueous phase was measured to find it was 2.5.

[0508] (Adsorption purification process)

[0509] 2.0 g of activated clay was added to the organic phase n1, and after stirring for 20 minutes, the activated clay was filtered to obtain an organic phase n2.

[0510] (Water washing process)

[0511] The obtained organic phase n2 was returned to the separable flask again, 100 g of water was added, and after stirring for 15 minutes, it was allowed to stand for 10 minutes to separate the two phases to obtain an organic phase n3 and an aqueous phase n4. The aqueous phase n4 was taken out into a heat-resistant bottle, cooled to 25°C, and the conductivity was measured to be 320.1 μS / cm. Water was added to the organic phase n3 again, and the same operation was performed to obtain an organic phase n5. The final conductivity of the aqueous phase was 3.8 μS / cm. The number of water washes required for the conductivity of the aqueous phase to meet the requirement of less than 10 μS / cm was 4 times, and the amount of waste water was 3.3 g relative to 1 g of the waste polycarbonate resin composition supplied to the decomposition process.

[0512] (Crystallization process)

[0513] Thereafter, the organic phase n5 was cooled to 10°C to obtain a slurry. The obtained slurry was filtered to obtain 65 g of a fine filter cake. The obtained fine filter cake was dried using a rotary evaporator to obtain 51 g of bisphenol A. The yield was 47 mol% (51 g ÷ 228 g / mol ÷ 0.472 × 100 = 47 mol%). The APHA of the bisphenol A melt was 52.

[0514] [Comparative Example 6]

[0515] (Decomposition process)

[0516] The same operation as in the decomposition step of Comparative Example 5 was carried out, and after confirming the generation of bisphenol A, 227 g of a 10% sodium hydroxide aqueous solution was supplied to obtain a decomposition liquid containing bisphenol A.

[0517] (Coarse crystallization process)

[0518] The obtained decomposition liquid was slowly cooled from 90°C to 10°C to obtain slurry. The obtained slurry was filtered to obtain 145 g of a coarse cake (solid content) and 615 g of a coarse crystallization mother liquor. 450 g of warm water was sprayed on the coarse cake to wash away phenol on the surface of the crystals.

[0519] Composition analysis of a portion of the washed crude cake by high performance liquid chromatography confirmed that the cake was an adduct crystal in which phenol was added to bisphenol A.

[0520] (Redissolution process)

[0521] The adduct crystals were returned to a jacketed separable flask equipped with a Dimrot condenser, a stirring blade, and a thermometer, 600 g of toluene was added, and the adduct crystals were dissolved by heating to 75° C. to obtain an organic phase o1 (redissolved liquid) containing bisphenol A. The pH was measured by the same method as in Example 1 and the pH was 6.2.

[0522] (Adsorption purification process)

[0523] 2.0 g of activated clay was added to the organic phase o1, and after stirring for 20 minutes, the activated clay was filtered to obtain an organic phase o2.

[0524] (Water washing process)

[0525] The obtained organic phase o2 was returned to the separable flask again, 100 g of water was added, and after stirring for 15 minutes, it was allowed to stand for 10 minutes to separate the two phases, thereby obtaining an organic phase o3 and an aqueous phase o4. The aqueous phase o4 was taken out into a heat-resistant bottle, cooled to 25°C, and the conductivity was measured to be 1003 μS / cm. Water was added to the organic phase o3 again, and the same operation was performed to obtain an organic phase o5. The final conductivity of the aqueous phase was 4.0 μS / cm. The number of water washings required to satisfy the conductivity of the aqueous phase of less than 10 μS / cm was 5 times, and the amount of waste water was 4.2 g relative to 1 g of the waste polycarbonate resin composition supplied to the decomposition step.

[0526] (Crystallization process)

[0527] Thereafter, the temperature of the organic phase o5 was lowered to 10° C. to obtain a slurry. The obtained slurry was filtered to obtain 68 g of a refined filter cake.

[0528] The obtained refined cake was dried by a rotary evaporator to obtain 50 g of bisphenol A. The yield was 46 mol% (50 g÷228 g / mol÷0.472×100=46 mol%). The APHA of the bisphenol A melt was 56.

[0529] [Comparative Example 7]

[0530] (Decomposition process)

[0531] The polycarbonate resin was decomposed under the same conditions as in Example 7 to obtain a decomposition liquid.

[0532] (Coarse crystallization process)

[0533] The decomposed liquid obtained in the decomposition step was crystallized and washed in the same manner as in Example 7 to obtain a coarse cake.

[0534] (Redissolution process)

[0535] The obtained crude cake was dissolved in the same manner as in Example 7 to obtain an organic phase p1 (redissolved liquid) containing bisphenol A. The pH was measured in the same manner as in Example 1 and found to be 7.3.

[0536] (Water washing process)

[0537] The obtained organic phase p1 was subjected to the same operation as the water washing step of Example 1, and was washed with water five times to make the conductivity of the water phase satisfy 10 μS / cm or less, thereby obtaining an organic phase p2. The conductivity of the fifth water phase was 3.1 μS / cm. The amount of waste water was 2.5 g relative to 1 g of the polycarbonate resin composition containing the light diffusion material supplied to the decomposition step.

[0538] (Crystallization process)

[0539] Thereafter, the organic phase p2 was cooled to 10°C to obtain a slurry. The obtained slurry was filtered, and the obtained fine filter cake was dried using a rotary evaporator to obtain 108 g of bisphenol A. The yield was 60 mol% (108 g ÷ 228 g / mol ÷ 0.783 × 100 = 60 mol%). The APHA of the bisphenol A melt was 420, and it was significantly turbid. The L* (brightness) of the bisphenol A melt was 55.2.

[0540] [Comparative Example 8]

[0541] (Decomposition process)

[0542] The polycarbonate resin was decomposed under the same conditions as in Example 8 to obtain a decomposed liquid.

[0543] (Coarse crystallization process)

[0544] The decomposition liquid obtained in the decomposition step was crystallized and washed in the same manner as in Example 8 to obtain a coarse filter cake.

[0545] (Redissolution process)

[0546] The obtained crude cake was dissolved in the same manner as in Example 8 to obtain an organic phase r1 (redissolved liquid) containing bisphenol A. The pH was measured in the same manner as in Example 1 and found to be 7.3.

[0547] (Water washing process)

[0548] The obtained organic phase r1 was subjected to the same operation as the water washing step of Example 1, and five water washings were performed to obtain an organic phase r2 in order to make the conductivity of the water phase satisfy 10 μS / cm or less. The conductivity of the fifth water phase was 2.8 μS / cm. The amount of waste water was 2.5 g relative to 1 g of the aluminum-deposited polycarbonate resin composition supplied to the decomposition step.

[0549] (Crystallization process)

[0550] Thereafter, the organic phase r2 was cooled to 10°C to obtain a slurry. The obtained slurry was filtered, and the obtained fine filter cake was dried using a rotary evaporator to obtain 107 g of bisphenol A. The yield was 60 mol% (107 g ÷ 228 g / mol ÷ 0.783 × 100 = 60 mol%). The APHA of the bisphenol A melt was 65.

[0551] [Comparative Example 9]

[0552] (Decomposition process)

[0553] The polycarbonate resin was decomposed under the same conditions as in Example 9 to obtain a decomposition liquid.

[0554] (Coarse crystallization process)

[0555] The decomposition liquid obtained in the decomposition step was crystallized and washed in the same manner as in Example 9 to obtain a coarse filter cake.

[0556] (Redissolution process)

[0557] The obtained crude cake was dissolved in the same manner as in Example 9 to obtain an organic phase s1 (redissolved liquid) containing bisphenol A. The pH was measured in the same manner as in Example 1 and found to be 8.7.

[0558] (Water washing process)

[0559] The obtained organic phase s1 was subjected to the same operation as the water washing step of Example 1, and was washed with water four times to make the conductivity of the water phase satisfy 10 μS / cm or less, thereby obtaining an organic phase s2. The conductivity of the fourth water phase was 3.3 μS / cm. The amount of waste water was 2.0 g relative to 1 g of the polycarbonate resin composition containing titanium oxide supplied to the decomposition step.

[0560] (Crystallization process)

[0561] Thereafter, the organic phase s2 was cooled to 10°C to obtain a slurry. The obtained slurry was filtered, and the obtained fine filter cake was dried using a rotary evaporator to obtain 109 g of bisphenol A. The yield was 61 mol% (109 g ÷ 228 g / mol ÷ 0.783 × 100 = 61 mol%). The APHA of the bisphenol A melt was 510, and it was significantly turbid. The L* (brightness) of the bisphenol A melt was 49.4.

[0562] [Comparative Example 10]

[0563] (Decomposition process)

[0564] The polycarbonate resin was decomposed under the same conditions as in Example 10 to obtain a decomposed liquid.

[0565] (Coarse crystallization process)

[0566] The decomposition liquid obtained in the decomposition step was crystallized and washed in the same manner as in Example 10 to obtain a coarse cake.

[0567] (Redissolution process)

[0568] The obtained crude cake was dissolved in the same manner as in Example 10 to obtain an organic phase t1 (redissolved liquid) containing bisphenol A. The pH was measured in the same manner as in Example 1 and found to be 8.7.

[0569] (Water washing process)

[0570] The obtained organic phase t1 was subjected to the same operation as the water washing step of Example 1, and was washed with water four times to make the conductivity of the aqueous phase satisfy 10 μS / cm or less, thereby obtaining an organic phase t2. The conductivity of the fourth aqueous phase was 4.2 μS / cm. The amount of waste water was 2.0 g relative to 1 g of the polycarbonate resin composition containing carbon black supplied to the decomposition step.

[0571] (Crystallization process)

[0572] Thereafter, the organic phase t2 was cooled to 10°C to obtain a slurry. The obtained slurry was filtered, and the obtained fine filter cake was dried using a rotary evaporator to obtain 107 g of bisphenol A. The yield was 60 mol% (107 g ÷ 228 g / mol ÷ 0.783 × 100 = 60 mol%). The APHA of the bisphenol A melt was 220, and it was colored black. The L* (brightness) of the bisphenol A melt was 74.5.

[0573] The results of Examples 6 to 10 are summarized in Table 3, and the results of Comparative Examples 5 to 10 are summarized in Table 4. As can be seen from Examples 7 to 10 in Table 3 and Comparative Examples 7 to 10 in Table 4, it is difficult to completely remove the additives in the decomposition raw material by a general bisphenol purification method without adsorption purification, which causes the deterioration of the color tone of the regenerated bisphenol. However, by performing adsorption purification, the additives can be efficiently removed, and regenerated bisphenol with excellent color tone (nearly colorless and not turbid) can be obtained. In addition, as can be seen from Example 6 in Table 3 and Comparative Examples 5 to 6 in Table 4, by performing adsorption purification in a state where the adsorbed purified liquid is alkaline, the yield rate is improved and the amount of waste water can be reduced.

[0574] [Table 3]

[0575]

[0576] [Table 4]

[0577]

[0578] [Example 11]

[0579] Into a glass reaction tank with a content of 45 mL equipped with a stirrer and a distillation tube, 10.00 g (0.04 mol) of bisphenol A obtained in Example 8, 9.95 g (0.05 mol) of diphenyl carbonate, and 18 μL of a 400 mass ppm cesium carbonate aqueous solution were added. The glass reaction tank was depressurized to about 100 Pa and then returned to atmospheric pressure with nitrogen gas three times to replace the interior of the reaction tank with nitrogen gas. Thereafter, the reaction tank was immersed in an oil bath at 220° C. to dissolve the contents.

[0580] The rotation speed of the stirrer was set to 100 times per minute, and the pressure in the reaction vessel was reduced from 101.3 kPa to 13.3 kPa in absolute pressure over 40 minutes while distilling off phenol produced as a by-product by the oligomerization reaction of bisphenol A and diphenyl carbonate in the reaction vessel.

[0581] Thereafter, while the external temperature of the reaction vessel was raised to 290° C., the pressure in the reaction vessel was reduced from 13.3 kPa to 399 Pa in absolute pressure over 40 minutes, and the distilled phenol was removed to the outside of the system.

[0582] Thereafter, the absolute pressure of the reaction tank was reduced to 30 Pa to carry out the polycondensation reaction. The polycondensation reaction was terminated when the stirrer of the reaction tank reached a predetermined stirring power. The time from heating to 290° C. to the completion of the polymerization was 135 minutes.

[0583] Next, the reaction tank was restored to an absolute pressure of 101.3 kPa with nitrogen gas, and then the pressure was increased to 0.2 MPa by gauge pressure, and the polycarbonate resin was taken out from the reaction tank to obtain the polycarbonate resin. The viscosity average molecular weight (Mv) of the obtained polycarbonate resin was 26,100.

[0584] [Comparative Example 11]

[0585] A polycarbonate resin was polymerized in the same manner as in Example 11 except that the bisphenol A obtained in Comparative Example 6 was used.

[0586] While distilling off phenol produced as a by-product by the oligomerization reaction of bisphenol A and diphenyl carbonate in the reaction vessel, the absolute pressure was reduced from 101.3 kPa to 13.3 kPa. However, phenol stopped distilling off during the reaction and polymerization did not proceed beyond that level.

[0587] [Comparative Example 12]

[0588] A polycarbonate resin was polymerized in the same manner as in Example 11 except that the bisphenol A obtained in Comparative Example 8 was used.

[0589] The polymerization reaction proceeded slowly compared to Example 11, and it took 235 minutes from the time the temperature was raised to 290° C. to the time the polymerization was completed. The viscosity average molecular weight (Mv) of the obtained polycarbonate resin was 19,900.

[0590] The results of Example 11 and Comparative Examples 11 and 12 are summarized in Table 5.

[0591] [Table 5]

[0592]

Claims

1. A method for producing bisphenol, characterized in that: It has the following adsorption purification process: The adsorbed purified liquid containing bisphenol and an organic solvent is brought into contact with an adsorbent material to purify the adsorbed purified liquid to obtain an adsorbed purified liquid. The adsorbed purified liquid is alkaline.

2. The method for producing bisphenol according to claim 1, wherein The pH of the adsorbed purified liquid is above 7.

1.

3. The method for producing bisphenol according to claim 1 or 2, wherein: The adsorbed purified liquid contains a bisphenol analog, and the bisphenol analog has a structure in which at least two carbon atoms on a benzene ring constituting the bisphenol skeleton are double-bonded with oxygen atoms.

4. The method for producing bisphenol according to claim 1 or 2, wherein: The water content in the adsorbed purified liquid is 10 mass % or less.

5. The method for producing bisphenol according to claim 1 or 2, wherein: The content of the organic solvent in the adsorbed purified liquid is 20% by mass or more.

6. The method for producing bisphenol according to claim 1 or 2, wherein: The organic solvent includes at least one selected from the group consisting of benzene, toluene, xylene, phenol, cresol, dichloromethane, dimethyl carbonate, and diethyl carbonate.

7. The method for producing bisphenol according to claim 1 or 2, wherein: The adsorbent material includes any one selected from the group consisting of activated clay, acid clay, activated carbon, and cation exchange resin.

8. The method for producing bisphenol according to claim 1, comprising the following decomposition step: Prior to the adsorption purification step, the raw material resin in the decomposition raw material containing the raw material resin is chemically decomposed to obtain the bisphenol, and the raw material resin is a polycarbonate resin and / or an epoxy resin.

9. The method for producing bisphenol according to claim 8, wherein: The decomposition raw material is waste plastic containing the raw material resin.

10. The method for producing bisphenol according to claim 9, wherein: The waste plastic includes a metal layer and / or a resin layer formed of a resin other than the raw material resin.

11. The method for producing bisphenol according to claim 8 or 9, wherein: The decomposition raw material is a resin composition containing the raw material resin and fine particles and / or a polar low molecular compound.

12. The method for producing bisphenol according to claim 8 or 9, wherein: The decomposition raw material is a resin composition containing the raw material resin and one or more selected from the group consisting of a light diffusing material, an ultraviolet absorber, a colorant, an antioxidant, a flame retardant, and a release agent.

13. The method for producing bisphenol according to claim 8 or 9, wherein: The concentration of the decomposition raw material is 10% by mass, and the value obtained by multiplying the Hazen color APHA of the dichloromethane solution by 10 is 200 or more. The produced bisphenol was heated and melted at 175° C. for 30 minutes to obtain a melt having a Hazen color APHA of 100 or less.

14. The method for producing bisphenol according to claim 8 or 9, wherein: The lightness L* of a dichloromethane solution containing the decomposition raw material at a concentration of 10% by mass is 80 or less, The bisphenol produced was heated and melted at 175° C. for 30 minutes to obtain a melt having a lightness L* of 90 or more.

15. The method for producing bisphenol according to claim 8 or 9, wherein: The raw material resin is decomposed in the presence of at least one decomposing agent selected from the group consisting of water, aromatic monohydric alcohols and aliphatic monohydric alcohols.

16. The method for producing bisphenol according to claim 8 or 9, wherein: The decomposition step and the step of preparing an adsorbed purified liquid are performed before the adsorption purification step. In the step of preparing an adsorbed purified liquid, the adsorbed purified liquid is prepared from the decomposition liquid containing bisphenol obtained in the decomposition step.

17. The method for producing bisphenol according to claim 8 or 9, wherein: The decomposition step and the concentration step are performed before the adsorption purification step. In the concentration step, the decomposition liquid containing bisphenol obtained by the decomposition step is concentrated by distillation to prepare an alkaline concentrated liquid. The adsorption purification step is a step of bringing the concentrated liquid into contact with the adsorbent to obtain the adsorption purified liquid. The solution removed in the concentration step is supplied to the decomposition step and reused.

18. The method for producing bisphenol according to claim 8 or 9, wherein: Prior to the adsorption purification step, the decomposition step, the coarse crystallization step and the redissolution step are performed. In the coarse crystallization step, the decomposition liquid containing bisphenol obtained in the decomposition step or the concentrated liquid obtained by concentrating the decomposition liquid is crystallized to separate the solid and liquid into a solid component containing bisphenol and a coarse crystallization mother liquid to obtain a solid component containing bisphenol. In the re-dissolving step, the solid component containing bisphenol is re-dissolved to prepare an alkaline re-dissolved liquid. The adsorption purification step is a step of bringing the re-dissolved liquid into contact with the adsorbent material to obtain the adsorption purified liquid. The coarse crystallization mother liquid separated into solid and liquid in the coarse crystallization step is supplied to the decomposition step and reused.

19. The method for producing bisphenol according to claim 1 or 2, comprising a water washing step and a fine crystallization step. In the water washing step, the adsorption purified liquid is mixed with water, and then phase-separated into an organic phase containing bisphenol and an aqueous phase, and the aqueous phase is removed to obtain the organic phase. In the crystallization step, bisphenol is precipitated from the organic phase obtained in the water washing step. In the production method, the water washing step is repeatedly performed until the conductivity of the removed water phase becomes 10 μS / cm or less, and then the fine crystallization step is performed.

20. The method for producing bisphenol according to claim 1 or 2, further comprising a bisphenol synthesis step of obtaining the bisphenol from a ketone or an aldehyde and an aromatic monohydric alcohol, wherein the bisphenol synthesis step comprises the following steps A0 to D0: The adsorption purification liquid is supplied to any one or more of the following steps A0 to D0, Step A0: a step of subjecting the ketone or aldehyde to dehydration condensation with the aromatic monohydric alcohol in the presence of an acid catalyst to obtain a reaction solution containing the bisphenol; Step B0: a step of removing the unreacted ketone or aldehyde and water from the reaction solution obtained in the step A0 by distillation to obtain a concentrated solution; Step C0: a step of crystallizing the concentrated liquid obtained in the step B0, and subjecting the obtained slurry liquid to solid-liquid separation to separate into a mother liquid and a filter cake; Step D0: A step of purifying the filter cake obtained in the step C0 to obtain the bisphenol.

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

22. The method for producing bisphenol according to claim 21, further comprising a bisphenol A synthesis step comprising the following steps A1 to G1: The adsorption purification liquid is supplied to any one or more of the following steps A1 to G1, Step A1: a step of subjecting acetone and phenol to dehydration condensation in the presence of an acid catalyst to obtain a reaction solution containing bisphenol A; Step B1: a step of distilling off unreacted acetone and water from the reaction liquid obtained in the step A1 to obtain a concentrated liquid; Step C1: a step of crystallizing the concentrated liquid obtained in the step B1, and subjecting the obtained slurry liquid to solid-liquid separation to separate into a mother liquid and a filter cake; Step D1: a step of purifying the filter cake obtained in the step C1 to obtain bisphenol A; Step E1: a step of circulating a part of the mother liquid obtained in the step C1 and supplying the mother liquid to the step A1; Step F1: a step of decomposing bisphenol A in the mother liquid obtained in the step C1 into phenol and isopropenylphenol under alkaline conditions, and then re-bonding phenol and isopropenylphenol to generate bisphenol A, thereby obtaining a solution containing bisphenol A; Step G1: a step of supplying the solution obtained in the step F1 to the step A1.

23. A method for producing a polycarbonate resin, comprising the following steps: A step of obtaining bisphenol by the method for producing bisphenol according to claim 1 or 2; and A step of producing a polycarbonate resin using a bisphenol raw material containing the obtained bisphenol.

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