JP2012136624A - Method for producing aromatic polyether sulfone - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing an aromatic polyether sulfone by which a recovered diphenyl sulfone (a solvent for reaction) having high purity is easily obtained and productivity of the aromatic polyether sulfone is enhanced.SOLUTION: The method for producing the aromatic polyethersulfone is provided in which condensation reaction of a biphenol compound (1) and a dihalogenated biphenyl compound (2) is performed in the coexistence of a specific base and a diphenyl sulfone being a solvent. In the method, the diphenyl sulfone is solvent-extracted from a reaction mixture after the reaction, by the recovered solvent, the obtained extraction liquid is passed through an ion exchange resin to refine the liquid and then the recovered solvent is distilled off to recover the diphenyl sulfone.

Description

  The present invention relates to a method for producing an aromatic polyethersulfone by subjecting a biphenol compound and a dihalogenated biphenyl compound to a condensation reaction.

Aromatic polyethersulfone is useful as a polymer compound excellent in heat resistance, impact resistance, transparency and the like. Such aromatic polyethersulfone is usually produced by subjecting a predetermined biphenol compound and a dihalogenated biphenyl compound to a condensation reaction in the presence of a base and diphenylsulfone as a reaction solvent.
The resulting aromatic polyethersulfone is obtained by removing by-product salts (inorganic salts such as potassium chloride), which are reaction products of hydrogen halide and base, from the reaction mixture containing the aromatic polyethersulfone with water, The reaction mixture is purified by separating and removing diphenylsulfone by solvent extraction (Patent Document 1).

Japanese Patent Application Laid-Open No. 2004-315764

Since diphenyl sulfone has a high boiling point and excellent stability at high temperatures, it is useful as a reaction solvent when producing an aromatic polyether sulfone by the condensation reaction, and it is preferably reused. In Patent Document 1, diphenylsulfone is separated and recovered from the reaction mixture by solvent extraction, but the by-product salt that remains without being removed in the water-washing and removing step of the by-product salt, which is the previous step, is extracted diphenyl sulfone. It is mixed in sulfone. Therefore, the extracted diphenylsulfone is passed through a heat exchanger to distill off the extraction solvent, and when diphenylsulfone is recovered, by-product salts remaining in the extraction solvent are deposited, and the heat exchanger is blocked. There is a fear.
In addition, since the purity of recovered diphenylsulfone is reduced by the residual by-product salt, the physical properties of the obtained aromatic polyethersulfone are reduced when the recovered diphenylsulfone is reused as it is for the production of aromatic polyethersulfone. (For example, the degree of coloring becomes remarkable).

  In order to solve such a problem, in Patent Document 1, after distilling the extraction solvent, the recovered diphenylsulfone is washed with water, and then the water is removed, whereby the purity of the recovered diphenylsulfone is improved and the degree of coloring Discloses that an aromatic polyethersulfone having a low viscosity can be obtained.

  However, the method of Patent Document 1 requires water washing and subsequent water removal in the recovery of diphenylsulfone, which increases the number of steps and reduces the productivity of aromatic polyethersulfone. It was. Moreover, washing with water may be an operating condition under high temperature and pressure.

  Accordingly, an object of the present invention is to provide a method for producing an aromatic polyethersulfone that can easily recover a reaction solvent such as diphenylsulfone with high purity and that can improve the productivity of the aromatic polyethersulfone. It is in.

  As a result of intensive studies to solve the above problems, the present inventors have obtained diphenyl recovered by removing by-product salts remaining in the extraction solvent obtained by solvent extraction of the reaction solvent from the reaction mixture with an ion exchange resin. Since the sulfone has a high purity, the present invention has been completed by finding a new fact that the productivity of the aromatic polyethersulfone can be improved by reusing it as a reaction solvent. .

［式中、Ｙは−ＳＯ₂−を表す。Ｒ¹〜Ｒ⁸は、それぞれ独立に、水素原子、炭素数１〜４のアルキル基または炭素数１〜４のアルコキシ基を表す。］

（式中、Ｚは−ＳＯ₂−を表し、Ｒ⁹〜Ｒ¹⁶は、それぞれ独立に、水素原子、炭素数１〜４のアルキル基または炭素数１〜４のアルコキシ基を表す。ＸおよびＸ'は、それぞれ独立にハロゲン原子を表す。）
具体的には、本発明の製造方法は、下記の第一工程〜第五工程を含むものである。
（第一工程）
前記塩基と反応溶媒の共存下に、前記式（１）で示されるビフェノール化合物と前記式（２）で示されるジハロゲン化ビフェニル化合物を縮合反応させて、該縮合反応により脱離したハロゲン化水素と前記塩基との反応生成物である副生塩と、反応溶媒と、芳香族ポリエーテルとを含む反応混合物を得る工程、
（第二工程）
得られた反応混合物から、前記副生塩を除去し、その後、反応溶媒を回収溶媒で溶媒抽出して、芳香族ポリエーテルスルホンを得る工程、
（第三工程）
第二工程で反応溶媒を抽出した抽出液をイオン交換樹脂に通して精製し、次いで回収溶媒を留去して、反応溶媒を回収する工程。
（第四工程）
前記塩基と、第三工程で得たジフェニルスルホンの共存下に、前記のビフェノール化合物（１）とジハロゲン化ビフェニル化合物（２）を縮合反応させて、前記のハロゲン化水素と塩基との反応生成物である副生塩と、ジフェニルスルホンと、芳香族ポリエーテルスルホンとを含む反応混合物を得る工程、
（第五工程）
前記（第二工程）〜（第四工程）を繰り返す工程。 That is, the method for producing an aromatic polyethersulfone of the present invention comprises a base that is an alkali metal carbonate and / or an alkali metal bicarbonate and a biphenol compound represented by the following formula (1) in the presence of a reaction solvent: A method for producing an aromatic polyethersulfone by a condensation reaction with a dihalogenated biphenyl compound represented by the following formula (2), wherein the reaction solvent is extracted from the reaction mixture after the reaction with a recovered solvent, and obtained. The extracted liquid is purified after passing through an ion exchange resin and then recovered.

[Wherein Y represents —SO ₂ —. R ^{1 to} R ⁸ each independently represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms. ]

(In the formula, Z represents —SO ₂ —, and R ^{9 to} R ¹⁶ each independently represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms. X and X 'Each independently represents a halogen atom.)
Specifically, the production method of the present invention includes the following first to fifth steps.
(First step)
In the presence of the base and the reaction solvent, the biphenol compound represented by the formula (1) and the dihalogenated biphenyl compound represented by the formula (2) are subjected to a condensation reaction, Obtaining a reaction mixture comprising a by-product salt which is a reaction product with the base, a reaction solvent, and an aromatic polyether;
(Second step)
Removing the by-product salt from the resulting reaction mixture, and then extracting the reaction solvent with a recovery solvent to obtain an aromatic polyethersulfone;
(Third process)
A step of purifying the extract obtained by extracting the reaction solvent in the second step through an ion exchange resin, and then recovering the reaction solvent by distilling off the recovered solvent.
(Fourth process)
In the presence of the base and diphenylsulfone obtained in the third step, the biphenol compound (1) and the dihalogenated biphenyl compound (2) are subjected to a condensation reaction, whereby the reaction product of the hydrogen halide and the base is obtained. Obtaining a reaction mixture comprising a by-product salt, diphenylsulfone, and aromatic polyethersulfone,
(Fifth process)
A step of repeating (second step) to (fourth step).

  The biphenol compound represented by the formula (1) may be 4,4′-dihydroxydiphenylsulfone, and the dihalogenated biphenyl compound represented by the formula (2) may be 4,4′-dichlorodiphenylsulfone.

  The base may be at least one selected from the group consisting of sodium carbonate, potassium carbonate, sodium bicarbonate and potassium bicarbonate.

  The ion exchange resin may be a cation exchange resin and an anion exchange resin.

  According to the present invention, by removing the by-product salt from the reaction mixture containing the aromatic polyethersulfone obtained by the condensation reaction, the reaction solvent is subjected to solvent extraction to obtain the aromatic polyethersulfone and the reaction solvent is recovered. A reaction solvent obtained by purifying an extract obtained by solvent extraction with a solvent through an ion exchange resin has high purity, and thus can be reused as a reaction solvent. Therefore, an aromatic solution can be used without increasing the number of steps. There is an effect that the productivity of the polyethersulfone can be improved.

The aromatic polyether sulfone according to the present invention condenses a biphenol compound represented by the above formula (1) and a dihalogenated biphenyl compound represented by the following formula (2) in the presence of a base and diphenyl sulfone as a reaction solvent. Produced by reaction.
As an alkyl group represented by R < ¹ > -R < ⁸ > in the said Formula (1), C1-C4 alkyl groups, such as a methyl group, an ethyl group, n-propyl group, t-butyl group, are mentioned, for example. . Moreover, as an alkoxy group represented by R < ¹ > -R < ⁸ >, C1-C4 alkoxy groups, such as a methoxy group, an ethoxy group, n-butoxy group, t-butoxy group, are mentioned, for example.

  Among the biphenol compounds represented by the formula (1), 4,4′-dihydroxydiphenylsulfone, or at least one carbon atom selected from the 3-position, 5-position, 3′-position and 5′-position of the compound has a methyl group Bound compounds are preferred, especially 4,4′-dihydroxydiphenyl sulfone.

As a C1-C4 alkyl group represented by R < ⁹ > -R < ¹⁶ > in the said Formula (2), the alkyl group similar to the group demonstrated in R < ¹ > -R < ⁸ > in Formula (1) is mentioned, for example. . Further, the alkoxy group having 1 to 4 carbon atoms represented by R ⁹ to R ¹⁶ in Formula (2), for example, include the same alkoxy groups as described in R ¹ to R ⁸ in Formula (1) It is done. Examples of the halogen atom represented by X and X ′ include fluorine, chlorine, bromine and the like, and fluorine or chlorine is particularly preferable.

  Among the dihalogenated biphenyl compounds represented by the formula (2), 4,4′-dichlorodiphenylsulfone, 4,4′-difluorodiphenylsulfone, or the 3-position, 5-position, 3′-position and 5 ′ of these compounds A compound in which a methyl group is bonded to at least one carbon atom selected from the above positions is preferred. In particular, 4,4′-dichlorodiphenyl sulfone is preferable.

（式中、Ａは−ＳＯ₂−を表し、Ｒ¹⁷〜Ｒ²⁴は、それぞれ独立に、水素原子、炭素数１〜４のアルキル基または炭素数１〜４のアルコキシ基を表す。Ｘ"はハロゲン原子を表す。）で示されるモノハロゲン化ビフェニル化合物を共存させてもよい。 In the present invention, when the biphenol compound (1) is reacted with the dihalogenated biphenyl compound (2), the following formula (3)

(In the formula, A represents —SO ₂ —, and R ^{17 to} R ²⁴ each independently represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms. X ″ represents A monohalogenated biphenyl compound represented by the formula (1) represents a halogen atom.

Examples of the alkyl group represented by R ^{17 to} R ²⁴ in the monohalogenated biphenyl compound (3) include the same alkyl groups having 1 to 4 carbon atoms as those described for R ^{1 to} R ⁸ in the formula (1). Is mentioned. Examples of the alkoxy group represented by R ^{17 to} R ²⁴ in the monohalogenated biphenyl compound (3) include the same alkoxy groups having 1 to 4 carbon atoms as those described for R ^{1 to} R ⁸ in the formula (1). Is mentioned. X ″ in the monohalogenated biphenyl compound (3) represents a halogen atom, and examples of the halogen atom include the same atoms as X and X ′ in the formula (2).

  Among the monohalogenated biphenyl compounds (3), 4- (4-chlorophenylsulfonyl) phenol, 4- (4-fluorophenylsulfonyl) phenol and the like are preferable.

Next, an embodiment of the production method of the present invention will be described. In this embodiment,
A first step of obtaining a reaction mixture comprising diphenyl sulfone and aromatic polyether by a condensation reaction;
A second step in which by-product salts are removed from the obtained reaction mixture, and then diphenylsulfone is subjected to solvent extraction with a recovery solvent;
A third step of passing the extract through an ion exchange resin to remove residual by-product salts and recovering diphenyl sulfone;
Using the recovered diphenylsulfone, a condensation reaction of the biphenol compound (1) and the dihalogenated biphenyl compound (2) to obtain a reaction mixture;
-The process of repeating said 2nd process-4th process is included.

Hereinafter, each process is demonstrated in order.
(First step)
In the first step, in the presence of a specific base and diphenylsulfone as a reaction solvent, the biphenol compound (1) and the dihalogenated biphenyl compound (2), and if necessary, the monohalogenated biphenyl compound (3) A reaction mixture containing aromatic polyethersulfone produced by condensation reaction, by-product salt (KCl, NaCl, etc.), which is a reaction product of hydrogen halide and base eliminated by the condensation reaction, and diphenylsulfone. Get.

  The proportion of the compounds (1), (2) and (3) used is usually compound (2) and compound (1) relative to a total of 1 equivalent of the phenolic hydroxyl groups contained in compound (1) and compound (3). The total amount of halogen atoms contained in 3) is in the range of 0.9 to 1.1 equivalents, preferably in the range of 0.98 to 1.05 equivalents. Specifically, for example, when an aromatic polyether is produced by a condensation reaction of the compound (1) and the compound (2), the compound (2) is usually 0 with respect to 1 equivalent of the compound (1). It is used in the range of 0.9 to 1.1 equivalents, preferably in the range of 0.98 to 1.05 equivalents.

  The base used in the present invention is an alkali metal carbonate and / or an alkali metal bicarbonate. Of these, sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate and the like are preferable. The amount of the base used is usually 1 equivalent or more with respect to 1 equivalent of the total phenolic hydroxyl group in the compounds (1), (2) and (3), preferably about 1.005 to 1.25 equivalents. It is. It is preferable that the amount of the base used is 1.25 equivalents or less with respect to 1 equivalent of the phenolic hydroxyl group because side reactions tend to be reduced. Moreover, since the molecular weight of the aromatic polyether obtained as the usage-amount of a base is 1 equivalent or more with respect to 1 equivalent of phenolic hydroxyl group tends to increase, it is preferable.

  In the production method of the present invention, the condensation reaction temperature is usually in the range of 210 to 320 ° C, preferably in the range of 240 to 290 ° C. When the condensation reaction temperature exceeds 210 ° C., the molecular weight of the resulting aromatic polyether tends to increase, and when it is less than 320 ° C., coloring tends to be reduced. The time required for the condensation reaction varies depending on the types of the compounds (1), (2) and (3), the reaction mode, the reaction temperature, etc., but is usually about 1 to 24 hours, preferably about 2 to 12 hours. It is.

  The mixing and reaction of the compounds (1), (2) and (3) are preferably carried out under an inert gas stream. Thereby, coloring due to oxidation of the compounds (1), (2) and (3) and the aromatic polyethersulfone which is a product of the condensation reaction can be reduced.

  The condensation reaction in the present invention can usually be stopped by cooling the reaction mixture containing the aromatic polyethersulfone. Further, for the purpose of inactivating the terminal phenoxide of the aromatic polyethersulfone, a halide or the like may be added to stop the polymerization reaction. Examples of the halide include aliphatic halides such as methyl chloride, ethyl chloride, and methyl bromide; 4-chlorodiphenyl sulfone, 4-fluorodiphenyl sulfone, 4-chlorobenzophenone, 4-fluorobenzophenone, 4,4′-difluoro Aromatic halides such as diphenylsulfone, 4,4′-dichlorodiphenylsulfone, 4,4′-difluorobenzophenone, p-chloronitrobenzene and the like can be mentioned.

(Second step)
In the second step, the by-product salt is removed from the reaction mixture obtained in the first step, and then aromatic polyethersulfone and diphenylsulfone are separated to obtain aromatic polyethersulfone.
Examples of the method for removing the by-product salt from the obtained reaction mixture and isolating the aromatic polyethersulfone after the completion of the condensation reaction include the following methods. First, a mixture of aromatic polyethersulfone, by-product salt and diphenylsulfone is cooled and solidified, and then pulverized. Next, by washing the pulverized product with water, most of the by-product salt is removed, and then the solid diphenyl sulfone is dissolved from the reaction mixture after the by-product salt is removed, but the aromatic polyether sulfone is not dissolved. Diphenylsulfone is extracted using a solvent, and aromatic polyethersulfone is separated.

Examples of the recovery solvent that dissolves diphenylsulfone but does not dissolve aromatic polyether include low-boiling solvents such as methanol, acetone, isopropanol, methyl ethyl ketone, and ethanol, and mixtures thereof.
The aromatic polyether sulfone separated from the diphenyl sulfone is further substituted with water, washed with water, dehydrated and dried to obtain the desired aromatic polyether sulfone.

(Third process)
In the third step, in order to separate the aromatic polyethersulfone from the second step, the solvent-extracted extract containing diphenylsulfone is passed through an ion exchange resin to remove residual salt such as KCl. To do. Recovered diphenylsulfone is obtained by evaporating and recovering the recovered solvent from the extract that has passed through the ion exchange resin.

  As the ion exchange resin, a cation exchange resin and an anion exchange resin are used. The proportion of the cation exchange resin and the anion exchange resin used is usually preferably equal to or close to the weight by weight. Specifically, for example, the cation exchange resin is about 45 to 55% by weight, the anion The exchange resin is about 55 to 45% by weight, and the ion exchange capacity is preferably about cation exchange capacity / anion exchange capacity = about 0.9 to 1.1.

  The order of passing the ion exchange resin is usually passed through the anion exchange resin after passing through the cation exchange resin, but may be reversed. Moreover, you may mix and use a cation exchange resin and an anion exchange resin. Although it does not specifically limit as an average particle diameter of an ion exchange resin, Usually, a cation exchange resin is about 600-700 micrometers, and an anion exchange resin is about 600-800 micrometers.

  The temperature and pressure when the diphenylsulfone solvent extract is passed through the ion exchange resin may usually be room temperature and normal pressure. By this ion exchange treatment, the by-product salt can be efficiently removed in a liquid state that is easy to handle and under mild conditions, so that the heat exchanger is not clogged during the subsequent solvent distillation, and is recovered. The purity of the resulting diphenylsulfone increases.

  Next, diphenyl sulfone is recovered by evaporating a recovery solvent (extraction solvent) that is a low-boiling point solvent or a low-boiling point solvent mixture from the extract that has passed through the ion exchange resin. The temperature of the liquid when evaporating the recovered solvent is usually in the range of 125 to 200 ° C. If the temperature is lower than 125 ° C., diphenyl sulfone is solidified and loses fluidity. The evaporated recovery solvent is condensed and recovered, and then distilled to remove water, so that it can be reused as a recovery solvent for extraction.

(Fourth process)
In the fourth step, the biphenol compound (1) and the dihalogenated biphenyl compound (2) are subjected to a condensation reaction in the presence of the base and the diphenyl sulfone recovered in the third step, and an aromatic polyether, diphenyl sulfone, To obtain a reaction mixture containing by-product salts.

(Fifth process)
In the fifth step, the second to fourth steps are repeated. In the present invention, since the recovered diphenylsulfone is highly pure and contains almost no by-product salt, diphenylsulfone can be used repeatedly in these steps.

  The aromatic polyethersulfone obtained by the production method of the present invention can be made into a resin having excellent transparency by drying as necessary. Moreover, a desired molded article can also be obtained by an injection molding machine, an extrusion molding machine, etc. using the obtained aromatic polyether sulfone. When molding with a molding machine, reactive fiber coupling agents such as glass fiber such as milled glass fiber and chopped glass fiber, inorganic filler, silane coupling agent, titanate coupling agent, borane coupling agent, Higher fatty acids, higher fatty acid esters, higher fatty acid metal salts, lubricants such as fluorocarbon surfactants, mold release improvers such as fluororesins and metal soaps, nucleating agents, antioxidants, stabilizers, plasticizers, lubricants, Coloring agents, coloring agents, ultraviolet absorbers, antistatic agents, lubricants, flame retardants, and the like may be added. However, it is preferable not to use additives that reduce transparency such as glass fibers, inorganic fillers, and colorants for applications requiring transparency such as glass substitute materials.

  EXAMPLES Hereinafter, although an Example etc. demonstrate this invention in detail, this invention is not limited by these Examples.

Example 1- (1)
[Production example of aromatic polyethersulfone using reagent-grade diphenylsulfone]
In a reaction vessel equipped with a stirrer, a nitrogen inlet tube, a thermometer, and a condenser with a receiver at the tip, 100.11 parts by weight of 4,4′-dihydroxydiphenylsulfone as a monomer and 4,4 ′ as a monomer -After charging 119.92 parts by weight of dichlorodiphenylsulfone and 196 parts by weight of diphenylsulfone (light transmittance of 400 nm, 96.5%, manufactured by UCB) and replacing the inside of the container with a nitrogen atmosphere, nitrogen was further introduced into the container. While circulating, the temperature was raised to 180 ° C. to dissolve the monomer. Next, 57.5 parts by weight of anhydrous potassium carbonate was added. Thereafter, the temperature was gradually raised to 280 ° C., and the reaction was performed at the same temperature for 4.5 hours (corresponding to the first step of the present invention).

  After completion of the reaction, the reaction solution was cooled to room temperature, solidified, and finely pulverized. The obtained aromatic polyether, a by-product salt (KCl) produced by the neutralization reaction of the base (potassium carbonate) and hydrogen halide, and a diphenylsulfone powdery mixture are washed with warm water, and the by-product salt is obtained. Was removed. Next, diphenylsulfone was extracted from the mixture after removing the by-product salt with an acetone / methanol mixture, and the residue after extraction was heated to 150 ° C. to obtain an aromatic polyethersulfone (of the present invention). Corresponds to the second step).

Example 1- (2)
[Purification of recovered diphenylsulfone (corresponding to the third step of the present invention)]
In Example 1- (1), the extract obtained by extracting diphenyl sulfone with an acetone / methanol mixture from the mixture after removing the by-product salt was placed in a column packed with a mixed ion exchange resin at room temperature (23-27 ° C.). ) Under normal pressure to remove residual by-product salt (KCl).
The mixed ion exchange resin used has an apparent density of about 730 g / L, an average particle size of about 600 μm, and an exchange capacity ratio (cation exchange resin / anion exchange resin) of 0.9 to 1.1.
The representative composition of the extract immediately before passing through the mixed ion exchange resin is as follows.
46% by weight of acetone
40% by weight of methanol
9% by weight of water
Diphenyl sulfone 5% by weight
KCl 400wtppm
The ion exchange conditions are as follows.
Flow rate: 2003ml / hr
Column inner diameter: 20mm
Filling length: 0.66m
Empty speed: 6.38 vl / d
As a result, from the start up to 300 minutes, KCl from the effluent was 5 ppm or less, which is the detection limit. Recovered diphenylsulfone was obtained by evaporating acetone, methanol and water from the extract that passed through the ion exchange resin. KCl was detected by ion chromatography.

Claims (5)

Condensation of a biphenol compound represented by the following formula (1) and a dihalogenated biphenyl compound represented by the following formula (2) in the presence of a reaction solvent with a base that is an alkali metal carbonate and / or alkali metal bicarbonate. A method for producing an aromatic polyethersulfone by reacting, extracting the reaction solvent from the reaction mixture after the reaction with a recovery solvent, and purifying the resulting extract through an ion exchange resin; A process for producing an aromatic polyethersulfone, which is recovered.

[Wherein Y represents —SO ₂ —. R ^{1 to} R ⁸ each independently represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms. ]

(In the formula, Z represents —SO ₂ —, and R ^{9 to} R ¹⁶ each independently represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms. X and X 'Each independently represents a halogen atom.) The manufacturing method of aromatic polyether sulfone of Claim 1 including the following 1st process-5th process.
(First step)
In the presence of the base and the reaction solvent, the biphenol compound represented by the formula (1) and the dihalogenated biphenyl compound represented by the formula (2) are subjected to a condensation reaction, Obtaining a reaction mixture comprising a by-product salt which is a reaction product with the base, a reaction solvent, and an aromatic polyether;
(Second step)
Removing the by-product salt from the resulting reaction mixture, and then extracting the reaction solvent with a recovery solvent to obtain an aromatic polyethersulfone;
(Third process)
A step of purifying the extract obtained by extracting the reaction solvent in the second step through an ion exchange resin, and then recovering the reaction solvent by distilling off the recovered solvent.
(Fourth process)
In the presence of the base and diphenylsulfone obtained in the third step, the biphenol compound (1) and the dihalogenated biphenyl compound (2) are subjected to a condensation reaction, whereby the reaction product of the hydrogen halide and the base is obtained. Obtaining a reaction mixture comprising a by-product salt, diphenylsulfone, and aromatic polyethersulfone,
(Fifth process)
A step of repeating (second step) to (fourth step).   The production according to claim 2, wherein the biphenol compound represented by the formula (1) is 4,4'-dihydroxydiphenylsulfone, and the dihalogenated biphenyl compound represented by the formula (2) is 4,4'-dichlorodiphenylsulfone. Method.   The production method according to any one of claims 1 to 3, wherein the base is at least one selected from the group consisting of sodium carbonate, potassium carbonate, sodium bicarbonate and potassium bicarbonate.   The production method according to claim 1, wherein the ion exchange resin is a mixed ion exchange resin comprising a cation exchange resin and an anion exchange resin.