JP2016204271A - Method for recovering bisphenol fluorenes from resin including fluorene structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for efficiently recovering high-purity bisphenol fluorenes capable of being reutilized as a raw material for an optical resin from a polycarbonate resin having a fluorene structure.SOLUTION: In hydrolyzing a polycarbonate resin having a fluorene structure in the presence of a metal hydroxide aqueous solution to produce bisphenol fluorenes, distributing the bisphenol fluorenes produced by the hydrolysis into an organic solvent, and then separating a phase of the organic solvent and a phase of the metal hydroxide aqueous solution to recover the bisphenol fluorenes in the phase of the organic solvent, the hydroxide ion (OH) concentration of the metal hydroxide contained in the phase of the metal hydroxide aqueous solution before the separation is regulated to 0.35 mmol/g or less.SELECTED DRAWING: None

Description

  The present invention relates to a method for efficiently recovering bisphenolfluorenes as starting materials from waste or recovered polycarbonate resin having a fluorene structure with high quality. More specifically, a polycarbonate resin having a fluorene structure is hydrolyzed in the presence of an aqueous metal hydroxide solution, and the resulting bisphenol fluorenes are recovered in an organic solvent phase and can be reused as an optical resin raw material. The present invention relates to a method for obtaining bisphenolfluorenes in good yield.

  Polycarbonate with a fluorene structure is relatively excellent in high refractive index, low birefringence, transparency, processability, and heat resistance, and has recently been used as an optical resin material for optical lenses and optical films. The amount is increasing. In addition, since the amount of resin to be discarded increases as the demand for polycarbonate resin containing a fluorene structure increases, it has become important to reuse them. In particular, since bisphenol fluorenes, which are one of the starting materials, are more expensive than other raw materials, it has been desired to develop a method for efficiently recovering them as reusable materials.

  As a method for depolymerizing the polycarbonate resin, mainly, the polycarbonate resin is heated with phenol to convert to bisphenol A and diphenyl carbonate, and both are separated and recovered by distillation. In the presence of a base catalyst, The polycarbonate resin and lower alcohol are converted into bisphenol A and dialkyl carbonate by heat treatment, and the alcoholysis decomposition method in which both are separated and recovered by distillation, and the polycarbonate resin is reacted with an excess aqueous alkali solution to form bisphenol A. There are three known hydrolysis methods that decompose and recover. However, in the phenol decomposition method and alcohol decomposition method, by-products such as diphenyl carbonate or dialkyl carbonate are generated, and the process of separating and recovering the target bisphenols becomes complicated.

As a method for depolymerizing a polycarbonate resin by hydrolysis, for example, in Japanese Patent Application Publication “Japanese Patent Publication No. 40-16536” (Patent Document 1), polycarbonate and 1-30% aqueous alkali solution are put in a pressure vessel. Preferably, after hydrolysis at 150 ° C. or higher, the aqueous alkaline solution containing the decomposition product is acidified to precipitate the decomposition product, filtered, dissolved in methanol, treated with activated carbon to remove colored components, and then re-precipitated. A method for obtaining white bisphenol is disclosed. In Japanese Patent Publication “JP-A-54-48869” (Patent Document 2), a 15N sodium hydroxide aqueous solution is added to polycarbonate, saponified at 100 ° C., unsaponified components are separated, and a saponified mixture is obtained. A method for phosgenation and use in polycarbonate polymerization without purification is disclosed. In Japanese Patent Laid-Open Publication No. 2005-126358 (Patent Document 3), part or all of a waste aromatic polycarbonate resin is dissolved in an organic solvent composed of a chlorinated compound and then decomposed with an aqueous metal hydroxide solution. Then, water is added to the decomposition solution, the precipitated solid content is dissolved, the aqueous phase and the organic solvent phase are separated, and the aqueous phase is recovered to obtain an aromatic dihydroxy compound metal salt aqueous solution. . In addition, in Japanese Patent Publication No. 2005-162675 (Patent Document 4), an acid is added to an aqueous solution of an aromatic dihydroxy compound metal salt obtained in the same manner as Patent Document 3 to precipitate the aromatic dihydroxy compound. A method for obtaining a solid of an aromatic dihydroxy compound by filtration and washing is disclosed.

However, the methods of Patent Documents 1 and 2 require severe reaction conditions of high temperature and / or high pressure, and the operation is complicated such as using a large amount of water in the post-treatment and further requiring reprecipitation operation. is there. In the method of Patent Document 2, since the decomposition product is reused for the polymerization reaction of the resin without purification operation, the additive and the colorant are mixed in the resin as they are and affect the product quality. In the methods of Patent Documents 3 and 4, an organic solvent composed of a chlorinated compound such as methylene chloride is used to dissolve the polycarbonate resin, and there are concerns about adverse effects on safety and the environment. Equipment is necessary. Further, in the methods of Patent Documents 3 and 4, since acid treatment is necessary for taking out crystals of the aromatic dihydroxy compound, the operation becomes complicated and the amount of waste increases. In each of the conventional methods described in Patent Documents 1 to 4, bisphenols are recovered in an aqueous phase as an aqueous metal salt solution of bisphenols, and acid treatment is required to extract them as crystals.

  The above-mentioned conventional method is a depolymerization method suitable for recovering bisphenol A from a polycarbonate using 2,2-bis (4-hydroxyphenyl) propane (commonly called bisphenol A) as a raw material, and has a fluorene structure. It was necessary to develop a suitable method for recovering bisphenolfluorenes having a specific structure from the polycarbonate resin.

Japanese Patent Publication No. 40-16536 JP 54-48869 A JP 2005-126358 A JP 2005-162675 A

  An object of the present invention is to provide a method for efficiently recovering high-purity bisphenolfluorenes that can be reused as a raw material for optical resins from a polycarbonate resin having a fluorene structure.

As a result of intensive research to solve the above-mentioned problems, the present inventors hydrolyzed a polycarbonate resin having a fluorene structure in the presence of an aqueous metal hydroxide solution to produce bisphenolfluorenes, and the hydrolysis By adjusting the amount of metal hydroxide in the aqueous metal hydroxide solution without special treatment such as acid treatment, the bisphenolfluorenes produced by the above process can be distributed with high selectivity in organic solvents. Furthermore, the recovered bisphenolfluorenes were found to be useful as a raw material for optical resins because of their high purity and good hue, and the present invention was completed.

That is, the present invention includes the following.

[1]
A polycarbonate resin having a fluorene structure is hydrolyzed in the presence of a metal hydroxide aqueous solution to obtain the following formula (1):

（式中、Ｒ_１a、及びＲ_１bはそれぞれ独立してアルキル基、シクロアルキル基、アルコキシ基又はアリール基を表す。複数のＲ_１a、及び／又はＲ_１bが存在する場合、それぞれは同一であっても異なっても良い。また、ｍ及びｎはそれぞれ独立して０又は１〜４の整数を表す。）
で表されるビスフェノールフルオレン類を生成させ、前記加水分解により生成した上記式（１）で表されるビスフェノールフルオレン類を有機溶媒中に分配させた後、有機溶媒の相と金属水酸化物水溶液の相とを分離して、上記式（１）で表されるビスフェノールフルオレン類を前記有機溶媒の相中に回収するビスフェノールフルオレン類の回収方法であって、分離前の前記金属水酸化物水溶液の相に含まれる金属水酸化物の水酸化物イオン（ＯＨ⁻）濃度が０．３５ｍｍｏｌ／ｇ以下であるビスフェノールフルオレン類の回収方法。

(In the formula, R _1a and R _1b each independently represent an alkyl group, a cycloalkyl group, an alkoxy group, or an aryl group. When a plurality of R _1a and / or R _1b are present, they are the same. And m and n each independently represents 0 or an integer of 1 to 4.)
The bisphenol fluorenes represented by the above formula (1) produced by the hydrolysis are distributed in an organic solvent, and then the organic solvent phase and the aqueous metal hydroxide solution A method for recovering bisphenolfluorenes by separating the phases and recovering the bisphenolfluorenes represented by the above formula (1) in the phase of the organic solvent, the phase of the aqueous metal hydroxide solution before the separation For recovering bisphenolfluorenes having a hydroxide ion (OH ⁻ ) concentration of 0.35 mmol / g or less.

[2]
After recovering the bisphenolfluorenes represented by the above formula (1) in the organic solvent phase, a step of adding an aqueous metal hydroxide solution to the obtained organic solvent phase; and The method for recovering bisphenolfluorenes according to [1], comprising a step of separating the phase from the phase of the aqueous metal hydroxide solution.

[3]
The method for recovering bisphenolfluorenes according to [1] or [2], wherein the organic solvent is at least one selected from the group consisting of aromatic hydrocarbons and aliphatic hydrocarbons.

[4]
The method for recovering bisphenolfluorenes according to [1] to [3], wherein crystals of the bisphenolfluorenes represented by the above formula (1) are obtained from the organic solvent layer by a crystallization operation.

  According to the present invention, high-quality bisphenolfluorenes that can be reused as an optical resin raw material can be efficiently recovered from a polycarbonate resin having a fluorene structure. Furthermore, since it is possible to separate diols and inorganic components that do not have a fluorene structure without significantly reducing the recovery rate of bisphenol fluorenes, it is possible to reduce waste and simplify purification operations. Efficient recovery of bisphenolfluorenes becomes possible.

Hereinafter, the present invention will be described in detail.
In the present invention, the polycarbonate resin having a fluorene structure is produced by a known method such as an interfacial polymerization method or a melt polymerization method using the bisphenol fluorene represented by the above formula (1) as a constituent raw material. Additives such as sealants and stabilizers may be included, and are interpreted in the broadest sense. Examples of the polycarbonate resin to be subjected to the depolymerization method of the present invention include a polycarbonate resin alone or a resin containing other components within a range not impairing the effects of the present invention, such as polyester carbonates; a resin composition combined with other components For example, a mixture of polycarbonate and polyester may be used. The shape is not limited to powder, pellets, sheets, films, molded products, etc., but discarded lenses and sheets; defective products, burrs generated during production and / or molding; production waste, ie polycarbonate Solids recovered from waste of products using resin, pulverized products thereof, and the like are used.

  Bisphenolfluorenes, which are constituent materials of the polycarbonate resin of the present invention and are recovered by the method of the present invention, have a structure represented by the following formula (1).

（式中、Ｒ_１a、及びＲ_１bはそれぞれ独立してアルキル基、シクロアルキル基、アルコキシ基又はアリール基を表す。複数のＲ_１a、及び／又はＲ_１bが存在する場合、それぞれは同一であっても異なっても良い。また、ｍ及びｎはそれぞれ独立して０又は１〜４の整数を表す。）

(In the formula, R _1a and R _1b each independently represent an alkyl group, a cycloalkyl group, an alkoxy group, or an aryl group. When a plurality of R _1a and / or R _1b are present, they are the same. And m and n each independently represents 0 or an integer of 1 to 4.)

Examples of the alkyl group in the above formula (1) include, for example, methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, s-butyl group, t-butyl group, pentyl group, hexyl group, etc. -20 linear or branched alkyl groups can be mentioned. The alkyl group is preferably a linear or branched alkyl group having 1 to 8 carbon atoms, more preferably a linear or branched alkyl group having 1 to 3 carbon atoms, and further preferably a methyl group or ethyl group. It is a group.

  Examples of the cycloalkyl group in the above formula (1) include a cyclopentyl group, a cyclohexyl group, an alkyl (for example, alkyl having 1 to 4 carbon atoms) substituted cyclopentyl group, an alkyl (for example, an alkyl having 1 to 4 carbon atoms) substituted cyclohexyl group, and the like. And a cycloalkyl group having 4 to 16 carbon atoms (preferably 5 to 8 carbon atoms) or an alkyl-substituted cycloalkyl group. The cycloalkyl group is preferably a cyclopentyl group or a cyclohexyl group.

Examples of the alkoxy group in the above formula (1) include a methoxy group, an ethoxy group, and a propoxy group. Preferably it is a C1-C6 linear or branched alkoxy group, More preferably, it is a C1-C3 linear or branched alkoxy group.

  Examples of the aryl group in the above formula (1) include a phenyl group, an alkyl (for example, alkyl having 1 to 4 carbon atoms) -substituted phenyl group, and a naphthyl group. The aryl group is preferably a phenyl group or an alkyl-substituted phenyl group (for example, a methylphenyl group, a dimethylphenyl group, an ethylphenyl group, etc.), and more preferably a phenyl group.

  The alkyl group, cycloalkyl group, and aryl group may have a substituent other than the alkyl group (for example, an alkoxyl group, an acyl group, a halogen atom, etc.).

M and n representing the number of substitutions in the above formula (1) are preferably 0 or 1-2, and more preferably 0 or 1. Also, m and n are typically the same.

Specific examples of the 9,9-bisphenolfluorenes represented by the above formula (1) include 9,9-bis (4-hydroxyphenyl) fluorene (common name: bisphenolfluorene), 9,9-bis [(4- Hydroxy-3-methyl) phenyl] fluorene (common name: biscresol fluorene), 9,9-bis [(4-hydroxy-3-ethyl) phenyl] fluorene, 9,9-bis [(4-hydroxy-3-tert) -Butyl) phenyl] fluorene, 9,9-bis [(3-hydroxy-6-methyl) phenyl] fluorene, 9,9-bis [(2-hydroxy-4-methyl) phenyl] fluorene, 9,9-bis [(2-hydroxy-4-ethyl) phenyl] fluorene, 9,9-bis [(4-hydroxy-3,5-dimethyl) phenyl] fluorene 9,9-bis [(4-hydroxy-2,6-dimethyl) phenyl] fluorene, 9,9-bis [(4-hydroxy-3,5-di-tert-butyl) phenyl] fluorene, 9,9 -Bis [(4-hydroxy-3-cyclohexyl) phenyl] fluorene, 9,9-bis [(4-hydroxy-3-phenyl) phenyl] fluorene and 9,9-bis [(4-hydroxy-3-methoxyphenyl) ) Fluorene and the like. These 9,9-bisphenol fluorenes may be used alone or as a mixture of two or more. Among these 9,9-bisphenolfluorenes, 9,9-bis (4-hydroxyphenyl) fluorene and 9,9-bis [(4-hydroxy-3-methyl) phenyl] fluorene are frequently used as optical resin materials. 9,9-bis [(4-hydroxy-3,5-dimethyl) phenyl] fluorene and 9,9-bis [(4-hydroxy-3-phenyl) phenyl] fluorene are preferred, and 9,9-bis [( 4-Hydroxy-3-methyl) phenyl] fluorene is particularly preferred.

  The polycarbonate resin of the present invention contains bisphenol fluorenes as a main component, but can contain other diol components as constituent materials. Other diol components can be used alone or in combination of two or more.

Specific examples of other diol components include alkylene glycol [eg, ethylene glycol, propylene glycol, 1,3-butanediol, neopentyl glycol, etc.]; alicyclic diol [eg, cyclohexanediol, cyclohexanedimethanol, tricyclo Decanedimethanol, adamantanediol, norbornanedimethanol, 2,2-bis (4-hydroxycyclohexyl) propane, isosorbide and the like]; aromatic diol [for example, 4,4′-dihydroxydiphenyl, 1,1′-bi-2 Naphthol, 1-bis (4-hydroxyphenyl) ethane, 1,1-bis (4-hydroxyphenyl) -1-phenylethane, 2,2-bis (4-hydroxyphenyl) propane (common name: bisphenol A), 2,2-bis [ 4-hydroxy-3-methyl) phenyl] propane, 1,1-bis (4-hydroxyphenyl) cyclohexane, 1,1-bis (4-hydroxyphenyl) -3,3,5-trimethylcyclohexane, 1,3- Bis (4-hydroxyphenyl) -5,7-dimethyladamantane, 4,4'-dihydroxydiphenyl sulfone, 4,4'-dihydroxydiphenyl ether, etc.]. Among these diol components, 2,2-bis (4-hydroxyphenyl) propane and isosorbide, which are often used in combination with a polycarbonate resin having a fluorene structure, are preferred, and 2,2-bis (4-hydroxyphenyl) propane is particularly preferred. .

The amount (mole) of carbonate bond contained in the polycarbonate resin of the present invention is calculated from the composition ratio of the other diol component and the molecular weight of the polycarbonate resin when the bisphenolfluorenes and other diol components constituting the polycarbonate resin are included. be able to. In addition, the molecular weight of the polycarbonate resin of this invention shows the weight average molecular weight of polystyrene conversion obtained by using the GPC apparatus mentioned later. In addition, when the constituent ratio of the bisphenolfluorenes and other diol components constituting the polycarbonate resin is unknown, for example, the polycarbonate resin is analyzed using ¹ H-NMR, and the ratio of the integrated values of typical peaks of each constituent component Can be determined from

In the present invention, the polycarbonate is decomposed (hydrolyzed) in the presence of an aqueous metal hydroxide solution. As the metal hydroxide used, an alkali metal or alkaline earth metal hydroxide is preferably used, and an alkali metal hydroxide is more preferable. Specifically, sodium hydroxide, potassium hydroxide, calcium hydroxide, barium hydroxide and the like are used, preferably sodium hydroxide or potassium hydroxide, and particularly inexpensive sodium hydroxide is preferable from the viewpoint of cost. These metal hydroxides can be used as any one kind or a mixture of two or more kinds.

The temperature for performing the decomposition reaction is usually 120 ° C. or lower, preferably less than 100 ° C., more preferably 30 ° C. to 90 ° C. A temperature of 120 ° C. or lower is preferable because the reaction liquid is less likely to be colored brown during the decomposition treatment. When the reaction liquid is colored, the hue of the bisphenolfluorenes tends to deteriorate or the purity tends to decrease due to the influence of the reaction liquid, so that the bisphenolfluorenes with good quality may not be recovered. Further, when the temperature is high (over 120 ° C.), a large amount of heating energy is required, and further, the reaction at the boiling point or higher requires a pressure vessel, so the temperature is set to 120 ° C. or lower. As a result, the required equipment cost can be reduced, which is economically advantageous. Moreover, when the said temperature is too low, decomposition reaction time becomes long and processing efficiency may be remarkably inferior.

The amount of metal hydroxide used for the decomposition reaction is preferably 2.0 to 8.0 mol, more preferably 2.1 to 3.5 mol, per 1 mol of carbonate bond in the polycarbonate resin. Usually, when depolymerizing polycarbonate with bisphenol A as the main component, 4.1 mol or more of metal hydroxide is generally used for 1 mol of carbonate bond, but the polycarbonate resin having a fluorene structure is decomposed. In the present invention, decomposition is possible even at 4.0 mol or less. If the amount of the metal hydroxide used is 2.0 mol or more, it is preferable because the decomposition reaction does not become too slow and the decomposition is sufficiently performed. Moreover, if it is 8.0 mol or less, cost can be suppressed and the amount of water required for washing and purification does not increase, which is economically advantageous. In addition, it is preferable that an acid or the like is used in the recovery step of the next step, and there is little need to adjust the hydroxide ion concentration of the metal hydroxide contained in the phase of the metal hydroxide aqueous solution.

  The metal hydroxide is used in the form of an aqueous solution. The concentration of the metal hydroxide is preferably 10% to 55% by weight, more preferably 20% to 50% by weight. When the concentration of the metal hydroxide is 10% by weight or more, the decomposition rate of the polycarbonate resin is not slow, and when the concentration of the metal hydroxide is 55% by weight or less, the alkali metal hydroxide is precipitated. This is preferable because the metal hydroxide aqueous solution is unlikely to become a slurry. When the metal hydroxide aqueous solution becomes a slurry, the rate of the decomposition reaction of the polycarbonate resin is reduced. Further, when the concentration of the metal hydroxide is 55% by weight or less, it is preferable because coloring and generation of impurities hardly occur and the recovered bisphenolfluorenes are excellent in quality.

  The decomposition reaction of the polycarbonate resin can also be performed in the presence of an organic solvent. By performing the decomposition reaction in the presence of an organic solvent, the decomposition reaction is faster than when no organic solvent is used, and the decomposition can be performed at a lower temperature. Usually, when decomposing a polycarbonate resin containing bisphenol A as a main constituent material, an organic solvent comprising a chlorinated compound such as methylene chloride, which is a good solvent for the polycarbonate resin, is used. It has been found that even if an aromatic hydrocarbon or aliphatic hydrocarbon that is not a good solvent but is easy to handle is used as the solvent, the decomposition reaction can be carried out more easily. For this reason, the decomposition reaction is preferably performed in the presence of at least one organic solvent selected from the group consisting of aromatic hydrocarbons and aliphatic hydrocarbons. In this invention, in the range which does not impair the effect of this invention, other solvents other than the solvent (for example, phenol and methanol) which react with polycarbonate resin can also be used together.

  The organic solvent used in the decomposition reaction of the polycarbonate resin may be any one as long as it does not react with the metal hydroxide, the polycart resin, and the bisphenol fluorenes generated by decomposition. Hydrocarbons or aliphatic hydrocarbons are preferred. Examples of the aromatic hydrocarbon or aliphatic hydrocarbon include toluene, xylene, mesitylene, pentane, hexane, heptane, octane, nonane, decane, cyclohexane, cyclodecane and the like. In particular, toluene or xylene is preferred.

  The amount of the organic solvent used when using the organic solvent is not particularly limited as long as the object of the present invention is achieved, but is preferably 40 to 2000 parts by weight, preferably 100 to 1000 parts by weight with respect to 100 parts by weight of the polycarbonate resin. A range is more preferred. When the amount of the organic solvent used is 40 parts by weight or more, the aromatic polycarbonate resin can be sufficiently dissolved, the amount of the insoluble part can be reduced, and the yield can be increased. When the amount of the organic solvent used is 2000 parts by weight or less, it is possible to suppress the decomposition rate during the decomposition reaction, to shorten the decomposition reaction time, and to suppress the solvent recovery cost. Therefore, it is preferable.

  After the polycarbonate resin having a fluorene structure is hydrolyzed in the presence of an aqueous metal hydroxide solution to produce bisphenol fluorenes by the above-described method, the produced bisphenol fluorenes are distributed to an organic solvent, and then the organic solvent phase is obtained. Collect in. The organic solvent used here may be an organic solvent that does not react with the polycarbonate resin, decomposition product, or metal hydroxide, can dissolve the bisphenolfluorenes represented by the above formula (1), and can be separated from water. It ’s fine. In particular, at least one selected from the group consisting of aromatic hydrocarbons and aliphatic hydrocarbons is preferable from the viewpoint of easy handling and availability. Specific examples include toluene, xylene, mesitylene, pentane, hexane, heptane, octane, nonane, decane, cyclohexane, and cyclodecane. In particular, toluene or xylene is preferred. These organic solvents can be used alone or as a mixture of two or more thereof as necessary.

The organic solvent can be added after the hydrolysis reaction, and the produced bisphenolfluorenes can be distributed in the organic solvent. In addition, as described above, an organic solvent is added in advance before the decomposition reaction, the hydrolysis reaction is performed in the presence of the organic solvent, and the produced bisphenolfluorenes can be dissolved in the organic solvent and distributed to the organic solvent as needed. it can. By performing the decomposition reaction in the presence of an organic solvent, the decomposition reaction is faster than when no organic solvent is used, and the decomposition can be performed at a lower temperature. Therefore, the decomposition reaction is preferably performed in the presence of the organic solvent. The resulting bisphenolfluorenes are dissolved and distributed in an organic solvent as needed.

  The amount of organic solvent used for partitioning and recovery depends on the solubility of the produced bisphenolfluorenes in the organic solvent, and is limited in particular if the amount can be recovered efficiently and selectively with minimal partitioning into the aqueous phase. However, it is preferably 40 to 2000 parts by weight, more preferably 100 to 1000 parts by weight, based on 100 parts by weight of the polycarbonate resin. When the amount of the organic solvent used is more than 40 parts by weight, it is possible to reduce the insoluble part, and also to reduce the distribution to the aqueous phase and increase the yield, which is preferable. When the amount is 2000 parts by weight or less, it is preferable because volume efficiency can be prevented from being lowered, and an increase in solvent recovery cost can be suppressed thereby.

  In the present invention, the bisphenol fluorenes recovered in the phase of the organic solvent are obtained by changing the amount of the metal hydroxide contained in the phase of the aqueous metal hydroxide solution used in the hydrolysis reaction to the phase of the organic solvent and the metal water. It is possible to recover more bisphenol fluorenes in the organic solvent by adjusting the ratio to be described later until immediately before the phase of the aqueous oxide solution is separated.

The amount of the metal hydroxide contained in the phase of the aqueous metal hydroxide solution before separation is such that the hydroxide ion (OH ⁻ ) concentration of the metal hydroxide is 0.35 mmol / g or less. The hydroxide ion concentration can be measured by a standard method such as pH measurement or titration, and metal hydroxide (polycarbonate resin) consumed by decomposition of polycarbonate from the total amount of metal hydroxide used in the decomposition reaction. 2 moles per 1 mole of carbonate bond in it) and the metal hydroxide consumed to form the phenol salt contained in the aqueous metal hydroxide phase. it can.

When the hydroxide ion concentration is higher than 0.35 mmol / g, the distribution of bisphenolfluorenes to the aqueous phase increases, and the recovery rate into the organic solvent decreases. Moreover, when the hydroxide ion concentration is less than 0.05 mmol / g, when other diol components other than bisphenolfluorenes are included as constituent raw materials, the distribution to the phases of these organic solvents is increased and recovered. The purity of bisphenol fluorenes may decrease. In such a case, it is possible to selectively remove other diol components other than bisphenol fluorenes contained in the recovered organic solvent phase by performing a post-cleaning step described later.

The total amount of the metal hydroxide contained in the phase of the aqueous metal hydroxide solution before separation is not particularly limited as long as the object of the present invention is achieved, but is hydroxylated with respect to 1 mol of carbonate bond in the polycarbonate resin. The amount of substance ions is 0.05 to 0.6 mol, preferably 0.15 to 0.5 mol. By setting it as the range described on the left, it becomes possible to more efficiently recover bisphenolfluorenes into a phase of an organic solvent.

If the amount of metal hydroxide (hydroxide ion (OH ⁻ ) concentration / total amount) contained in the phase of the aqueous metal hydroxide solution before separation is excessive from the above range, neutralize by adding an acid. It can be adjusted by doing. Moreover, when it is insufficient, it can adjust by adding a metal hydroxide so that it may become the range mentioned above. The acid used here may be an organic acid or an inorganic acid as long as it does not react with bisphenol fluorenes, but when an organic acid is used, an inorganic acid is preferable because it may be distributed to the phase of an organic solvent. In particular, sulfuric acid and hydrochloric acid are preferred from the viewpoint of easy industrial use. Moreover, when adding a metal hydroxide, the metal hydroxide used by the hydrolysis reaction mentioned above is used. When an acid or a metal hydroxide is added to adjust the amount of the metal hydroxide, it is preferable to stir for a certain time (for example, 30 minutes or more) after the addition.

  The amount of water contained in the phase of the aqueous metal hydroxide solution before separation is not particularly limited as long as the object of the present invention is achieved, but is usually 100 to 600 parts by weight with respect to 100 parts by weight of the polycarbonate resin. . By setting the amount of water to 100 parts by weight or more, the inorganic component generated by hydrolysis is sufficiently dissolved, and the liquid separation property can be improved. Moreover, volume efficiency improves by setting it as 600 parts weight or less, and more bisphenol fluorenes can be distributed to the phase of an organic solvent.

  The temperature at the time of separation is not particularly limited as long as the object of the present invention is achieved, but it is usually 20 to 90 ° C, preferably 65 to 85 ° C.

After separating the phase of the organic solvent containing bisphenolfluorenes and the phase of the aqueous metal hydroxide solution as described above, after performing the purification operation such as washing and adsorption as necessary, the phase of the organic solvent containing bisphenolfluorenes Crystals of bisphenolfluorenes can be obtained by precipitating crystals by an operation such as crystallization. In particular, since crystals of bisphenolfluorenes can be easily obtained, it is preferable to take out bisphenolfluorenes by a crystallization operation. Moreover, it is possible to improve the purity of the bisphenol fluorene obtained by performing the post-washing process mentioned later further about the phase of the organic solvent containing the bisphenol fluorene obtained by isolate | separating.

In the post-cleaning step, a metal hydroxide aqueous solution is newly added to the organic solvent phase containing the bisphenolfluorenes recovered by the above-described method, and the organic solvent phase and the metal hydroxide aqueous solution are added as necessary. After mixing, the organic solvent phase and the metal hydroxide aqueous solution phase are separated.

As the metal hydroxide used in the post-cleaning step, the metal hydroxide used when decomposing the polycarbonate resin having the fluorene structure described above can be used as appropriate. The amount of the metal hydroxide contained in the metal hydroxide aqueous solution is included in the phase of the metal hydroxide aqueous solution when the phase of the organic solvent and the phase of the metal hydroxide aqueous solution are separated. It is preferable that the hydroxide ion (OH ⁻ ) concentration be 0.07 mmol / g to 0.2 mmol / g. By setting the hydroxide ion concentration to 0.2 mmol / g or less, it is possible to suppress distribution of bisphenolfluorenes to the aqueous phase, and by setting it to 0.07 mmol / g or more, other diol components can be reduced. It is preferable because impurities such as the first can be selectively distributed to the water layer.

The total amount of metal hydroxide used in the post-cleaning step is not particularly limited as long as the object of the present invention is achieved. However, the amount of hydroxide ions is 0.1% relative to 1 mol of carbonate bond in the polycarbonate resin. 1 to 0.4 mol, preferably 0.15 to 0.35 mol. By setting the range shown on the left, it becomes possible to selectively distribute impurities such as other diol components to the aqueous layer while recovering bisphenolfluorenes into the organic solvent phase more efficiently. .

The amount of water in the aqueous solution containing the metal hydroxide is not particularly limited as long as the object of the present invention is achieved, but is usually 50 to 600 parts by weight with respect to 100 parts by weight of the polycarbonate resin. By setting the amount of water to 50 parts by weight or more, the inorganic component generated by hydrolysis is sufficiently dissolved, and the liquid separation property can be improved. Moreover, volume efficiency improves by setting it as 600 parts weight or less, and more bisphenol fluorenes can be distributed to the phase of an organic solvent.

Although the temperature at the time of implementing a post-cleaning process is not specifically limited in the range by which the objective of this invention is achieved, Usually, it is 20-90 degreeC, Preferably it implements at 65-85 degreeC. In order to carry out the post-cleaning step more efficiently, the organic solvent phase and the metal hydroxide aqueous solution are mixed by a conventional method such as stirring, and then the organic solvent phase and the metal hydroxide aqueous solution are mixed. It is preferable to separate these phases.

The organic solvent phase containing the bisphenolfluorenes obtained after the post-cleaning step described above is further subjected to purification operations such as washing and adsorption as necessary, and then crystals are precipitated by crystallization and other operations. Fluorene crystals can be obtained. In particular, since crystals of bisphenolfluorenes can be easily obtained, it is preferable to take out bisphenolfluorenes by a crystallization operation.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, this invention is not limited to these. Hereafter, each measured value measured about the bisphenol fluorenes and the polycarbonates which have a fluorene structure followed the following method and measurement conditions.

[1] Distribution amount and HPLC purity of each component HPLC measurement was performed under the following measurement conditions, and the distribution amount (molar ratio) of each component and HPLC were determined based on the value obtained by quantifying the obtained area value by the absolute calibration curve method. The purity was determined.

・ Device: “LC-2010AHT” manufactured by Shimadzu Corporation
・ Column: “L-column ODS” manufactured by the Chemical Substance Evaluation Research Organization
(5 μm, 4.6 mmφ × 250 mm),
Column temperature: 40 ° C
・ Detection wavelength: UV 254 nm,
-Mobile phase: A liquid = water, B liquid = acetonitrile,
-Mobile phase flow rate: 1.0 ml / min,
Mobile phase gradient: Liquid B concentration: 30% (0 minutes) → 100% (after 25 minutes) → 100% (after 35 minutes).

[2] Melting Point and Glass Transition Temperature Using a differential scanning calorimeter (“EXSTAR DSC 7020” manufactured by SII Nano Technology Co., Ltd.), the melting point and glass transition temperature were measured at a heating rate of 10 ° C./min.

[3] Polycarbonate resin molecular weight and decomposition product formation rate Using a high-speed GPC device ("HLC-8200 GPC, mobile phase: THF" manufactured by Tosoh Corporation), the weight average molecular weight of the polycarbonate resin is RI (differential refractive index). Measured with a detector (polystyrene conversion).
Moreover, the area percentage value at the time of performing GPC measurement of the reaction liquid on said measurement conditions was made into the production | generation rate of each component and a dimer.

[4] Hydroxide ion (OH ⁻ ) concentration of metal hydroxide contained in the phase of the aqueous metal hydroxide solution before separation Quantitative value when performing HPLC measurement under the above conditions (absolute calibration curve method) Thus, the amount of bisphenol fluorenes contained in the phase of the metal hydroxide aqueous solution and the amount of other diol components are calculated, and based on these values, the metal hydroxide contained in the phase of the metal hydroxide aqueous solution is expressed by the following equation: The amount of hydroxide ions of the product was calculated, and the concentration was calculated by dividing the obtained amount of hydroxide ions by the absolute amount (g) of the aqueous phase.

Amount of hydroxide ion of metal hydroxide contained in the phase of metal hydroxide aqueous solution (mol)
= Total amount of metal hydroxide used (mol)
-Number of carbonate bonds in polycarbonate resin (mol) x 2
-Total amount (mol) of bisphenol fluorenes contained in the phase of the aqueous metal hydroxide solution x 2
-Total amount (mol) of other diol components contained in the phase of the metal hydroxide aqueous solution x 2

(Synthesis Example 1) 9,9-bis (4-hydroxy-3-methylphenyl) fluorene (hereinafter referred to as biscresol fluorene: trade name TBIS-MP (Taoka Chemical Industries, Ltd.)) and 2,2-bis (4-hydroxy Synthesis of copolymeric polycarbonate of phenyl) propane (hereinafter referred to as bisphenol A) Into a reactor equipped with a thermometer, a stirrer, and a reflux condenser were charged 11515 parts of ion-exchanged water and 2000 parts of 48% sodium hydroxide aqueous solution. , Biscresol fluorene (HPLC purity 99.5%, melting point 223 ° C.) 1513 parts, bisphenol A 913 parts and hydrosulfite 5 parts were dissolved, methylene chloride 8592 parts was added, and phosgene 950 parts at 15-25 ° C. with stirring. After completion of the phosgene blowing, p-tert-butylphenol was blown in. A solution prepared by dissolving 48 parts of methylene chloride in 650 parts of methylene chloride and 333 parts of a 48% aqueous sodium hydroxide solution were added to emulsify, and then 2.8 parts of triethylamine was added and stirred at 28 to 33 ° C. for 1 hour to react. After completion of the reaction, the product was diluted with methylene chloride, washed with water, acidified with hydrochloric acid and washed with water, and when the conductivity of the aqueous phase was almost the same as that of ion-exchanged water, the methylene chloride phase was concentrated, Dehydration gave a solution with a polycarbonate concentration of 20%, and the solvent was removed from this solution to obtain a polycarbonate resin.The obtained polycarbonate resin had a molar ratio of constituent units of biscresol fluorene and bisphenol A. 50: 50. (Polymer yield 97%, glass transition temperature: 226 ° C., molecular weight 30000) After taking out the polycarbonate resin Was crushed in a mortar was amorphous solid.

Example 1
In a reactor equipped with a stirrer, a cooler, and a thermometer, 100 parts by weight of the polycarbonate resin solid material obtained in Synthesis Example 1 and 66 parts by weight of a 48% aqueous sodium hydroxide solution (2.5 mole times: vs. Synthesis Example 1) 600 parts by weight of toluene was added to the polycarbonate resin obtained in step 1), and the mixture was heated and stirred at 90 ° C. for 2 hours. When the reaction solution was analyzed by GPC, the high molecular weight substance disappeared, 49.8% was 9,9-bis (4-hydroxy-3-methylphenyl) fluorene, 49.7% was 2,2-bis. In (4-hydroxyphenyl) propane, 0.5% was decomposed into dimers. Next, 410 parts by weight of water was added to the reaction liquid, stirred at 80 ° C. for 30 minutes, and allowed to stand. Then, the hydroxide ion (OH ⁻ ) concentration of the metal hydroxide in the aqueous phase was calculated by the above method. .15 mmol / g.
Thereafter, the aqueous phase was separated and removed to obtain a toluene solution. This toluene solution was analyzed by HPLC. As a result, 9,9-bis (4-hydroxy-3-methylphenyl) fluorene and 2,2-bis (4-hydroxyphenyl) propane were detected. It was found that 99% and 35% of the theoretical amount of each component was recovered.
Furthermore, the 30 minutes stirring with toluene solution was added an aqueous solution of sodium 370 parts by weight hydroxide concentration 0.3 mmol / g 80 ° C., allowed to stand, the hydroxide ions of the metal hydroxide in the aqueous phase (OH ^-) The concentration calculated by the above method was 0.17 mmol / g.
Thereafter, the aqueous phase was separated and removed to obtain a toluene solution. The separated toluene solution was analyzed by HPLC. As a result, 9,9-bis (4-hydroxy-3-methylphenyl) fluorene and 2,2-bis (4-hydroxyphenyl) propane were added to the polycarbonate resin in the toluene solution. It was found that 96% and 2% of the theoretical amount of each component was recovered. Furthermore, this toluene solution was washed with water at 80 ° C. with 100 g of ion exchange water three times to remove inorganic components, and then the obtained toluene solution was cooled to room temperature to precipitate crystals. The precipitated crystals were filtered and dried to obtain 49 parts by weight of white crystals of 9,9-bis (4-hydroxy-3-methylphenyl) fluorene (recovery rate of 85% vs. 9,9-bis ( For 4-hydroxy-3-methylphenyl) fluorene). The white crystals had an HPLC purity of 99.0% and a melting point of 222 ° C.

(Example 2)
In Example 1, 66 parts by weight of the 48% aqueous sodium hydroxide solution was used as 71 parts by weight (2.8 mole times: relative to 1 mole of carbonate bond of the polycarbonate resin obtained in Synthesis Example 1). Except for the above, the same reaction was carried out for 3 hours, and the reaction solution was analyzed by GPC. As a result, the high molecular weight substance was lost, and 49.9% was 9,9-bis (4-hydroxy-3-methylphenyl) fluorene. 49.8% decomposed into 2,2-bis (4-hydroxyphenyl) propane and 0.3% into dimer. Next, 150 parts by weight of water was added to the reaction solution, stirred at 80 ° C. for 30 minutes, and allowed to stand. Then, the hydroxide ion (OH ⁻ ) concentration of the metal hydroxide in the aqueous phase was calculated by the above method. It was 30 mmol / g.
Thereafter, the aqueous phase was separated and removed to obtain a toluene solution. This toluene solution was analyzed by HPLC. As a result, 9,9-bis (4-hydroxy-3-methylphenyl) fluorene and 2,2-bis (4-hydroxyphenyl) propane were detected. It was found that 99% and 16% of the theoretical amount of each component was recovered.
Further, 370 parts by weight of a sodium hydroxide aqueous solution having a concentration of 0.15 mmol / g was added to this toluene solution, stirred at 80 ° C. for 30 minutes and allowed to stand, and then the hydroxide ion (OH ⁻ ) of the metal hydroxide of the aqueous phase When the concentration was analyzed by the above method, it was 0.1 mmol / g.
Thereafter, the aqueous phase was separated and removed to obtain a toluene solution. The obtained toluene solution was analyzed by HPLC. As a result, 9,9-bis (4-hydroxy-3-methylphenyl) fluorene and 2,2-bis (4-hydroxyphenyl) propane were added to the polycarbonate resin in the toluene solution. It was found that 97% and 3% of the theoretical amount of each component was recovered. Furthermore, this toluene solution was washed with water at 80 ° C. with 100 g of ion exchange water three times to remove inorganic components, and then the obtained toluene solution was cooled to room temperature to precipitate crystals. The precipitated crystals were filtered and dried to obtain 49 parts by weight of white crystals of 9,9-bis (4-hydroxy-3-methylphenyl) fluorene (recovery rate of 85% vs. 9,9-bis ( For 4-hydroxy-3-methylphenyl) fluorene). The white crystals had an HPLC purity of 99.2% and a melting point of 222 ° C.

(Comparative Example 1)
In Example 1, the amount of the 48% sodium hydroxide aqueous solution used was 66 parts by weight, except that it was 78 parts by weight (3.1 moles relative to 1 mole of the carbonate bond of the polycarbonate resin obtained in Synthesis Example 1). Performed the same operation for 3 hours, and the reaction solution was analyzed by GPC. As a result, the high molecular weight product disappeared and 49.9% was converted to 9,9-bis (4-hydroxy-3-methylphenyl) fluorene. , 49.9% decomposed into 2,2-bis (4-hydroxyphenyl) propane and 0.2% into dimer. Further, this reaction solution was allowed to stand at 80 ° C., and then the hydroxide ion (OH ⁻ ) concentration of the metal hydroxide in the aqueous phase was analyzed by the above method. As a result, it was 0.42 mmol / g.
Thereafter, the aqueous phase was separated and removed, and the aqueous phase was separated and removed to obtain a toluene solution. When this toluene solution was analyzed by HPLC, 9,9-bis (4-hydroxy-3-methylphenyl) fluorene was detected, and only 88% of the theoretical amount constituting the polycarbonate resin was found in the toluene solution. It was not recovered. The obtained aqueous phase was analyzed by HPLC. As a result, 9,9-bis (4-hydroxy-3-methylphenyl) fluorene contained 12% of the theoretical amount constituting the polycarbonate resin.

(Comparative Example 2)
In Example 1, 66 parts by weight of 48% aqueous sodium hydroxide solution was added to 78 parts by weight (3.1 moles relative to 1 mole of the carbonate bond of the polycarbonate resin obtained in Synthesis Example 1). The same operation was performed except that the amount used was changed to 600 parts by weight, and the reaction was performed for 3 hours. When the reaction solution was analyzed by GPC, the high molecular weight product disappeared and 49.9% was 9,9- In bis (4-hydroxy-3-methylphenyl) fluorene, 49.8% was decomposed into 2,2-bis (4-hydroxyphenyl) propane and 0.3% was decomposed into a dimer. Further, this reaction solution was allowed to stand at 80 ° C., and then the hydroxide ion (OH ⁻ ) concentration of the metal hydroxide in the aqueous phase was analyzed by the above method. As a result, it was 0.41 mmol / g.
Thereafter, the aqueous phase was separated and removed, and the aqueous phase was separated and removed to obtain a toluene solution. When this toluene solution was analyzed by HPLC, 9,9-bis (4-hydroxy-3-methylphenyl) fluorene was detected, and only 90% of the theoretical amount constituting the polycarbonate resin was found in the toluene solution. It was not recovered. Further, when the obtained aqueous phase was analyzed by HPLC, 9,9-bis (4-hydroxy-3-methylphenyl) fluorene contained 10% of the theoretical amount constituting the polycarbonate resin.

Claims (4)

A polycarbonate resin having a fluorene structure is hydrolyzed in the presence of a metal hydroxide aqueous solution to obtain the following formula (1):

(In the formula, R _1a and R _1b each independently represent an alkyl group, a cycloalkyl group, an alkoxy group, or an aryl group. When a plurality of R _1a and / or R _1b are present, they are the same. And m and n each independently represents 0 or an integer of 1 to 4.)
The bisphenol fluorenes represented by the above formula (1) produced by the hydrolysis are distributed in an organic solvent, and then the organic solvent phase and the aqueous metal hydroxide solution A method for recovering bisphenolfluorenes by separating the phases and recovering the bisphenolfluorenes represented by the above formula (1) in the phase of the organic solvent, the phase of the aqueous metal hydroxide solution before the separation For recovering bisphenolfluorenes having a hydroxide ion (OH ⁻ ) concentration of 0.35 mmol / g or less. After recovering the bisphenolfluorenes represented by the above formula (1) in the organic solvent phase, a step of adding an aqueous metal hydroxide solution to the obtained organic solvent phase; and The method for recovering bisphenolfluorenes according to claim 1, comprising a step of separating the phase from the phase of the aqueous metal hydroxide solution. The method for recovering bisphenolfluorenes according to claim 1 or 2, wherein the organic solvent is at least one selected from the group consisting of aromatic hydrocarbons and aliphatic hydrocarbons. The method for recovering bisphenolfluorenes according to any one of claims 1 to 3, wherein crystals of the bisphenolfluorenes represented by the formula (1) are obtained from the organic solvent layer by a crystallization operation.