WO2023218735A1

WO2023218735A1 - Purification method and production method for polyarylene sulfide

Info

Publication number: WO2023218735A1
Application number: PCT/JP2023/007708
Authority: WO
Inventors: 麻朗竹中; 高志古沢
Original assignee: Dic株式会社
Priority date: 2022-05-10
Filing date: 2023-03-02
Publication date: 2023-11-16

Abstract

Provided are a purification method and a production method that are for porous polyarylene sulfide (PAS) and that enlarge specific surface area of the same and reduce COD in waste water. In more detail, the PAS purification method and production method are characterized by comprising: a step (1) for obtaining a mixture containing crude PAS, by removing solvents from a crude reaction product that contains PAS and that is obtained by reacting, in an organic polar solvent, a polyhalo aromatic compound and a sulfidation agent; a step (2) for converting the crude PAS into porous particles having a specific surface area in a range of 30 [m²/g] or more, by bringing the mixture into contact with water and an oxygen atom-containing solvent having 1-3 carbon atoms; a step (3) for removing the oxygen atom-containing solvent from the mixture containing the porous particles; and a step (4) for bringing the obtained porous particles into contact with carbonated water. The methods are characterized in that the process for removing the solvent in the step (3) is a steam stripping process, and that the amount of steam used therein is 50 parts by mass or more with respect to 100 parts by mass of the porous particles of PAS.

Description

Purification method and manufacturing method of polyarylene sulfide

The present invention relates to a method for purifying and producing polyarylene sulfide.

Polyarylene sulfide (hereinafter sometimes abbreviated as PAS), represented by polyphenylene sulfide (hereinafter sometimes abbreviated as PPS), has excellent heat resistance and chemical resistance, and is used in electrical and electronic parts, automobile parts, It is widely used for water heater parts, textiles, films, etc. Among these, PAS porous materials are useful for chemical filtration to remove impurities in semiconductor manufacturing, as well as filtration of synthetic raw materials and organic solvents in pharmaceutical manufacturing, food manufacturing, and chemical industry manufacturing, by taking advantage of their excellent heat resistance and chemical resistance. It is expected that it will be used for such purposes.

As a method for producing porous particles using such PAS, a method is known in which PAS is polymerized and then a mixed solution containing a predetermined amount of water and N-methyl-2-pyrrolidone is added at high temperature. (See Patent Document 1). However, the obtained porous particles had a small specific surface area, and various functions based on porosity, such as ion exchange ability and oil absorption, were low.

There is also known a method of making PAS porous by contacting it with a specific organic solvent and water after polymerizing PAS (see Patent Document 2). However, PAS made porous by this method needs to be washed with water while containing a certain amount of solvent in order to maintain the specific surface area in the subsequent purification process, so the environmental impact of wastewater is an issue. Ta.

Japanese Unexamined Patent Publication No. 2-163126 JP2021-98815A

Therefore, the problem to be solved by the present invention is to provide a method for purifying porous PAS that has a large specific surface area and reduces the COD of wastewater, and a method for producing porous PAS that has a large specific surface area and reduces the COD of wastewater. It's about doing.

As a result of various studies, the inventors of the present application found that after making a mixture containing crude PAS porous by contacting it with a specific organic solvent and water, the specific organic solvent was removed using a steam stripping method. A purification method in which the porous crude PAS is brought into contact with water and carbon dioxide gas or carbonated water after removal of the The present invention was completed based on the discovery that the present invention is possible.

That is, the present disclosure provides a step of obtaining a mixture containing crude PAS ( 1) and
Step (2) of contacting a mixture containing crude PAS with water and an oxygen atom-containing solvent having 1 to 3 carbon atoms to form the crude PAS into porous particles having a specific surface area of 30 [m ² /g] or more. and,
a step (3) of removing the oxygen atom-containing solvent from the mixture containing the porous particles;
a step (4) of bringing the obtained porous particles into contact with carbonated water,
A method of removing the solvent in the step (3) is a steam stripping method, and the amount of steam is 50 parts by mass or more based on 100 parts by mass of the porous particles of PAS. Relating to a purification method.

The present disclosure also relates to a method for producing PAS, which includes a step of purifying PAS by the purification method described above.

According to the present invention, it is possible to provide a method for purifying porous PAS that has a large specific surface area and reduced COD of wastewater, and a method for producing porous PAS that has a large specific surface area and reduced COD of wastewater.

Hereinafter, one embodiment of the present disclosure will be described in detail, but the scope of the present disclosure is not limited to the one embodiment described here, and various changes can be made without departing from the spirit of the present disclosure. Additionally, if multiple upper and lower limit values are listed for a specific parameter, any of these upper and lower limit values may be combined to form a suitable numerical range. can.

One embodiment of the present disclosure relates to a method for purifying PAS. That is, the invention related to the method for purifying PAS purifies crude PAS by desolventizing a crude reaction product containing PAS obtained by reacting a polyhaloaromatic compound and a sulfidating agent in an organic polar solvent. step (1) of obtaining a mixture containing crude PAS, and contacting the mixture containing crude PAS with water and an oxygen atom-containing solvent having 1 to 3 carbon atoms so that the crude PAS has a specific surface area of 30 [m ² /g] or more; Step (2) of forming porous particles into porous particles, Step (3) of removing the oxygen atom-containing solvent from the mixture containing the porous particles, and Step (4) of bringing the obtained porous particles into contact with carbonated water. ), the method for removing the solvent in step (3) is a steam stripping method, and the amount of steam is 50 parts by mass or more based on 100 parts by mass of the PAS porous particles; It is characterized by The details will be explained below.

Process (1)
In the purification method according to the present embodiment, a mixture containing crude PAS is purified by desolventizing a crude reaction product containing PAS obtained by reacting a polyhaloaromatic compound and a sulfidating agent in an organic polar solvent. It has a step (1) of obtaining.

PAS is usually produced by reacting at least one polyhaloaromatic compound and at least one sulfidating agent under appropriate polymerization conditions in an organic polar solvent such as N-methyl-2-pyrrolidone. be synthesized.

The polyhaloaromatic compound used in the present disclosure is, for example, a halogenated aromatic compound having two or more halogen atoms directly bonded to an aromatic ring, and specifically includes p-dichlorobenzene, o- Dichlorobenzene, m-dichlorobenzene, trichlorobenzene, tetrachlorobenzene, dibromobenzene, diiodobenzene, tribromobenzene, dibromnaphthalene, triiodobenzene, dichlorodiphenylbenzene, dibromodiphenylbenzene, dichlorobenzophenone , dibrobenzophenone, dichlorodiphenyl ether, dibromidiphenyl ether, dichlordiphenyl sulfide, dibromidiphenyl sulfide, dichlorbiphenyl, dibrombiphenyl, and mixtures thereof, and these compounds can be used as block co-blocking agents. May be polymerized. Among these, preferred are dihalogenated benzenes, and particularly preferred are those containing 80 mol% or more of p-dichlorobenzene.

Furthermore, for the purpose of increasing the viscosity of PAS by creating a branched structure, a polyhaloaromatic compound having three or more halogen substituents in one molecule may be used as a branching agent as desired. Examples of such polyhaloaromatic compounds include 1,2,4-trichlorobenzene, 1,3,5-trichlorobenzene, and 1,4,6-trichloronaphthalene.

Furthermore, polyhaloaromatic compounds having functional groups with active hydrogen such as amino groups, thiol groups, and hydroxyl groups can be mentioned, and specifically, 2,6-dichloroaniline, 2,5-dichloroaniline, etc. , 2,4-dichloroaniline, dihaloanilines such as 2,3-dichloroaniline; 2,3,4-trichloroaniline, 2,3,5-trichloroaniline, 2,4,6-trichloroaniline, 3, Trihaloanilines such as 4,5-trichloroaniline; dihaloaminodiphenyl ethers such as 2,2'-diamino-4,4'-dichlorodiphenyl ether and 2,4'-diamino-2',4-dichlorodiphenyl ether Examples include compounds in which the amino group is replaced with a thiol group or a hydroxyl group in a mixture thereof.

In addition, active hydrogen-containing polyhaloaromatic compounds in which the hydrogen atom bonded to the carbon atom forming the aromatic ring in these active hydrogen-containing polyhaloaromatic compounds are substituted with other inert groups, for example, hydrocarbon groups such as alkyl groups. Aromatic compounds can also be used.

Among these various active hydrogen-containing polyhaloaromatic compounds, active hydrogen-containing dihaloaromatic compounds are preferred, and dichloroaniline is particularly preferred.

Examples of polyhaloaromatic compounds having a nitro group include mono- or dihalonitrobenzenes such as 2,4-dinitrochlorobenzene and 2,5-dichloronitrobenzene; 2-nitro-4,4'-dichlorodiphenyl ether, etc. dihalonitrodiphenyl ethers; dihalonitrodiphenyl sulfones such as 3,3'-dinitro-4,4'-dichlorodiphenylsulfone; 2,5-dichloro-3-nitropyridine, 2-chloro-3,5 - Mono- or dihalonitropyridines such as dinitropyridine; or various dihalonitronaphthalenes.

The sulfidating agents used in this disclosure include alkali metal sulfides such as lithium sulfide, sodium sulfide, rubidium sulfide, cesium sulfide, and mixtures thereof. Such alkali metal sulfides can be used as hydrates or aqueous mixtures or anhydrous. Furthermore, alkali metal sulfide can also be derived by reaction between alkali metal hydrosulfide and alkali metal hydroxide.

Incidentally, a small amount of alkali metal hydroxide may be added in order to react with the alkali metal hydrosulfide and alkali metal thiosulfate that are normally present in trace amounts in the alkali metal sulfide.

Organic polar solvents used in the present disclosure include N-methyl-2-pyrrolidone, formamide, acetamide, N-methylformamide, N,N-dimethylacetamide, 2-pyrrolidone, N-methyl-ε-caprolactam, and ε-caprolactam. , hexamethylphosphoramide, tetramethylurea, N-dimethylpropylene urea, amidourea of 1,3-dimethyl-2-imidazolidinonic acid, and lactams; sulfolanes such as sulfolane and dimethylsulfolane; benzonitrile, etc. Nitriles; ketones such as methyl phenyl ketone and mixtures thereof can be mentioned.

In the presence of these organic polar solvents, the polymerization conditions for the above-mentioned sulfidating agent and the polyhaloaromatic compound are generally at a temperature of 200 to 330°C, and a pressure that substantially removes the polymerization solvent and the polyhaloaromatic compound as a polymerization monomer. The pressure should be within a range such that the pressure is maintained in the liquid phase, and is generally selected from the range of 0.1 to 20 MPa, preferably 0.1 to 2 MPa. The reaction time varies depending on temperature and pressure, but is generally in the range of 10 minutes to 72 hours, preferably in the range of 1 hour to 48 hours.

The present disclosure also includes a form in which the crude reaction product is obtained by reacting a polyhaloaromatic compound and an organic polar solvent in the presence of a sulfidating agent and an organic polar solvent while continuously or intermittently adding the polyhaloaromatic compound and the organic polar solvent. do.

In the present disclosure, the crude reaction product containing PAS obtained from the polymerization reaction is processed by an appropriate method (such as a vacuum distillation method, a centrifugal separation method, a screw decanter method, a vacuum filtration method, a pressure filtration method, etc.). After separation and removal of the organic polar solvent, a mixture containing crude PAS can be obtained. At that time, the degree of separation and removal of the organic polar solvent is not particularly limited, but the proportion of solid content (solid content concentration) in the mixture is preferably 40 parts by mass or more, more preferably is 50 parts by mass or more, more preferably 55 parts by mass or more. Although the upper limit is not limited, it is preferably 100 parts by mass or less, more preferably less than 100 parts by mass, and even more preferably 99 parts by mass or less.

Process (2)
In the purification method according to the present embodiment, the mixture containing crude PAS is then brought into contact with water and an oxygen atom-containing solvent having 1 to 3 carbon atoms, so that the crude PAS has a specific surface area of 30 [m ² /g] or more. (2) to form porous particles in the range of .

Here, the oxygen atom-containing solvent having 1 to 3 carbon atoms to be brought into contact with the mixture containing crude PAS includes, for example, at least one selected from the group consisting of alcohol-based solvents and ketone-based solvents. Examples of alcoholic solvents (also referred to as alcoholic solvents) include methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, ethylene glycol, propylene glycol, and the like; 2-methoxyethyl alcohol, and the like. Moreover, acetone is exemplified as a ketone solvent (also referred to as a ketone solvent). In the present disclosure, monohydric alcohols having 3 or fewer carbon atoms are preferred. Alternatively, this step may be carried out using an aqueous solution prepared by adding water to a solvent containing an oxygen atom having 1 to 3 carbon atoms and reducing the concentration.

The temperature at which the oxygen atom-containing solvent having 1 to 3 carbon atoms is added is not particularly limited, but is preferably 10°C or higher, more preferably 20°C or higher, preferably 90°C or lower, and more preferably 70°C or lower. range. There is no particular restriction on the amount of the solvent used for one cleaning, but preferably 20 parts by mass or more, more preferably 50 parts by mass or more, still more preferably 100 parts by mass or more, per 100 parts by mass of PAS. , preferably 5,000 parts by mass or less, more preferably 1,800 parts by mass or less, still more preferably 600 parts by mass or less.

In the present disclosure, the crude PAS is made into porous particles having a specific surface area of 30 [m ² /g] or more, preferably 40 [m 2 /g], by contacting the crude PAS with an oxygen atom-containing solvent having 1 to 3 carbon atoms. ² /g] or more and 200 [m ² /g] or less, more preferably 60 [m ² /g] or more and 120 [m ² /g] or less. do. Note that the specific surface area can be measured by the method described in Examples.

Process (3)
The purification method according to the present embodiment subsequently includes a step (3) of removing the oxygen atom-containing solvent from the mixture containing the porous particles.

In this step, the method for removing the oxygen atom-containing solvent from the mixture containing the porous particles is not particularly limited as long as it uses a steam stripping method, and any known device or method can be used. That is, the treatment may be performed by bringing the mixture containing the porous particles into contact with steam, and removing volatile substances such as the oxygen atom-containing solvent contained in the mixture by volatilizing them together with the steam. For example, there is a device that agitates the mixture using a stirrer while supplying steam (for example, JP-A-4-292604, etc.), or a device that supplies steam to the mixture from the bottom and brings it into countercurrent contact within a multistage column (for example, Examples include Japanese Patent Publication No. 58-44086, Japanese Patent Application Publication No. 2018-58025, etc.), and vertical devices in which a steam nozzle is arranged below the liquid level of the mixture (for example, Japanese Patent Application Publication No. 9-220402, etc.).

The conditions for steam stripping are not particularly limited, but for example, the amount of steam to be contacted is preferably 50 parts by mass or more, and 100 parts by mass or more, based on 100 parts by mass of the theoretical yield of PAS contained in the mixture containing the porous particles. Parts by mass or more are more preferable. Further, for example, the flow rate of steam is preferably 0.5 kg/hr or more, more preferably 1.0 kg/hr or more per 1 kg of PAS. Within this range, the oxygen atom-containing solvent can be efficiently removed. Further, for example, the temperature at the time of contacting with steam is preferably 100°C or higher, and preferably 170°C or lower. Within this range, the water content of the mixture can be adjusted to an appropriate range. Further, for example, the pressure (gauge pressure) of the pot when contacting with steam is preferably 0.5 MPa or less, more preferably 0.3 MPa or less, and even more preferably atmospheric pressure or less. Steam may be blown from the bottom of the device, from the side of the device, or from multiple locations at the same time. Alternatively, the mixture containing the porous particles may be mixed in a pipe that supplies the apparatus and then enter the evaporation tank.

In this step, the mixture after the oxygen atom-containing solvent is removed by steam stripping contains water derived from steam. From the viewpoint of maintaining the specific surface area of the porous particles, the water content of the mixture is preferably 10 parts by mass or more, more preferably 20 parts by mass or more, based on 100 parts by mass of the mixture. Moreover, from the viewpoint of cleaning efficiency in step (4), the amount is preferably 250 parts by mass or less, and more preferably 200 parts by mass or less.

In addition to the oxygen atom-containing solvent, the volatile substances separated by the steam stripping process in this step may contain unreacted raw materials, organic polar solvents, PAS oligomers, byproducts, and the like. These materials may be further separated and recovered from the volatiles and reused in the production of other PAS.

Process (4)
The purification method according to the present embodiment subsequently includes a step (4) of bringing the obtained porous particles into contact with carbonated water.

In the present disclosure, the conditions for contacting the porous particles obtained in the preceding steps (1) to (3) with carbonated water are preferably 10°C or higher, more preferably 20°C or higher, and preferably 100°C. Hereinafter, the temperature is more preferably 80° C. or less, and the pressure (gauge pressure) is less than 0.1 MPa, preferably 0.05 MPa or less, and even more preferably atmospheric pressure.

There is no particular restriction on the amount of carbonated water used when bringing the porous particles into contact with the porous particles. Based on 100 parts by mass, preferably 50 parts by mass or more, more preferably 100 parts by mass or more, still more preferably 200 parts by mass or more, preferably 10,000 parts by mass or less, more preferably 5,000 parts by mass or less, still more preferably 2,000 parts by mass. The range is below parts by mass.

Another embodiment of the present disclosure relates to a method for producing PAS, which includes a step of refining PAS by the above-described purification method. That is, the invention related to the method for producing PAS is to remove crude PAS by desolventizing a crude reaction product containing PAS obtained by reacting a polyhaloaromatic compound and a sulfidating agent in an organic polar solvent. Step (1) of obtaining a mixture comprising;
Step (2) of contacting a mixture containing crude PAS with water and an oxygen atom-containing solvent having 1 to 3 carbon atoms to form the crude PAS into porous particles having a specific surface area of 30 [m ² /g] or more. and,
a step (3) of removing the oxygen atom-containing solvent from the mixture containing the porous particles;
a step (4) of bringing the obtained porous particles into contact with carbonated water,
The method for removing the solvent in step (3) is a steam stripping method.

The PAS obtained through the purification method or manufacturing method of the present disclosure may be dried as is, or may be further washed with water or an organic solvent as appropriate, followed by solid-liquid separation and dried.

Drying is performed by heating to a temperature at which the solvent such as water substantially evaporates. Drying may be carried out under vacuum, in air or under an inert atmosphere such as nitrogen.

PAS obtained through the purification method or manufacturing method of the present disclosure described above (sometimes simply referred to as "purified PAS") has the following characteristics. That is, the purified PAS of the present disclosure has a specific surface area of 10 [m ² /g] or more, preferably 15 [m ² /g] or more, more preferably 20 [m ² /g] or more, and preferably 180 [m 2 /g] or more. m ² /g] or less, preferably 150 [m ² /g] or less. Note that the specific surface area can be measured by the method described in Examples.

Further, the purified PAS of the present disclosure has a sodium content of 100 [ppm] or more, preferably 150 [ppm] or more, more preferably 200 [ppm] or more, preferably 500 [ppm] or less, more preferably 400 [ppm] or more. ppm] or less. In addition, the amount of sodium can be measured by the method of the example.

The PAS obtained through the purification method or production method of the present disclosure can be used as it is in various molding materials as before, but it can be thickened by heat treatment in air, oxygen-enriched air, or under reduced pressure. After performing such a thickening operation as necessary, it may be used in various molding materials. This heat treatment temperature varies depending on the treatment time and the atmosphere in which the treatment is carried out, so it cannot be absolutely defined, but it is usually preferably carried out at 180° C. or higher. If the heat treatment temperature is less than 180° C., the rate of viscosity increase will be very slow and productivity will be poor, which is not preferable. The heat treatment may be performed in a molten state using an extruder or the like at a temperature above the melting point of the polymer. However, in view of the possibility of deterioration of the polymer, workability, etc., it is preferable to carry out the reaction at a temperature of 100° C. or less above the melting point.

As in the past, the PAS obtained according to the present disclosure can be blended with fillers and other resins, melt-kneaded, directly or once formed into pellets, and then subjected to various processes such as injection molding, extrusion molding, compression molding, and blow molding. By the melt processing method, it is possible to make molded products with excellent heat resistance, moldability, dimensional stability, etc. However, in order to further improve performance such as strength, heat resistance, and dimensional stability, it is also possible to use it in combination with various fillers as long as the purpose of the present invention is not impaired. Examples of the filler include fibrous fillers and inorganic fillers. In addition, small amounts of mold release agents, colorants, heat stabilizers, ultraviolet stabilizers, foaming agents, rust preventives, flame retardants, lubricants, and cups may be used as additives during molding without departing from the purpose of the present invention. A ring agent can be included. Furthermore, the following synthetic resins and elastomers can be mixed and used in the same manner. These synthetic resins include polyester, polyamide, polyimide, polyetherimide, polycarbonate, polyphenylene ether, polysulfone, polyethersulfone, polyetheretherketone, polyetherketone, polyarylate, polyethylene, polypropylene, polytetrafluoroethylene, Examples of the elastomer include polydifluoroethylene, polystyrene, ABS resin, epoxy resin, silicone resin, phenol resin, urethane resin, and liquid crystal polymer, and examples of the elastomer include polyolefin rubber, fluorine rubber, and silicone rubber.

Molded products obtained by melt-molding PAS obtained according to the present disclosure or resin compositions containing the same have excellent heat resistance, dimensional stability, etc., as well as PAS obtained by conventional methods. Electrical and electronic parts such as encapsulation molded products, automotive parts such as lamp reflectors and various electrical components, interior materials for various buildings, aircraft, and automobiles, and precision parts such as OA equipment parts, camera parts, and clock parts, etc. It can be widely used as injection molded or compression molded products, or extrusion molded or pultruded products such as fibers, films, sheets, pipes, etc. Furthermore, by taking advantage of its porous nature, it is suitable for adsorbents, filter agents, catalyst carriers, and the like.

Hereinafter, the present disclosure will be explained using Examples and Comparative Examples, but the present disclosure is not limited to these Examples. In addition, hereinafter, unless otherwise specified, "%" and "part" are based on mass.

〔evaluation〕

(1) Measurement of the amount of oxygen atom-containing solvent in the mixture The amount of oxygen atom-containing solvent contained in the mixture after steam stripping treatment was evaluated. First, 10 g of the cake after steam stripping was taken and diluted by adding 15 g of an organic solvent (NMP). The solution was processed using a centrifuge at 500 rpm for 5 minutes. A solution obtained by adding monochlorobenzene as a standard substance to the obtained supernatant liquid was used as a measurement sample, and the measurement was performed using "Gas Chromatography GC-2014" manufactured by Shimadzu Corporation.

(2) Measurement of the amount of sodium in PPS The PPS obtained in Examples 1 to 5 and Comparative Examples 1 to 4 was weighed in a platinum crucible, and concentrated sulfuric acid (atomic absorption grade) was added thereto to cover the It was completely incinerated using a microwave ashing device manufactured by Stone General Co., Ltd. 1% hydrochloric acid and pure water were added thereto to dissolve the ash, and the solution was analyzed for sodium content using an atomic absorption spectrophotometer, and the sodium content in PPS was determined from the obtained value. In this operation, pure water with a conductivity of 18.2 MΩ·cm was used.

(3) Measurement of specific surface area (BET specific surface area) To measure the specific surface area of PPS, Tristar II3020 manufactured by Shimadzu Corporation was used. The PPS obtained in Examples 1 to 5 and Comparative Examples 1 to 4 was placed in a cell and degassed, then replaced with helium, cooled to -196°C, and further replaced with nitrogen to measure the specific surface area.

(4) Evaluation of chemical oxygen demand (COD) in wastewater After contacting a mixture containing PPS with carbonated water, COD was measured using the liquid phase component obtained by filtration as wastewater. 10 mL of waste water was collected, water was added to make 100 mL, and 10 mL of dilute sulfuric acid (sulfuric acid: water = 1:2, volume ratio) and 5 mL of silver nitrate aqueous solution (1.18 mol/L) were added and stirred. 10 mL of potassium manganate aqueous solution (5 mmol/L) was added and heated in a boiling water bath for 30 minutes. After heating, 10 mL of sodium oxalate aqueous solution (12.5 mmol/L) was added, and COD of the wastewater was obtained by titrating with potassium permanganate aqueous solution (5 mmol/L) while maintaining the temperature at 60°C. Evaluation was performed according to the following criteria.
〇: COD value of wastewater is less than 300mg/L ×: COD value of wastewater is 300mg/L or more

[Synthesis Example 1] Polymerization step of PPS 33.222 kg (226 mol) of p-dichlorobenzene (hereinafter abbreviated as DCB) and NMP2 were placed in a 150 L autoclave with stirring blades connected to a pressure gauge, thermometer, condenser, decanter, and rectification column. .280 kg (23 mol), 27.300 kg (230 mol as NaSH) of a 47.23 mass% NaSH aqueous solution, and 18.533 g (228 mol as NaOH) of a 49.21 mass% NaOH aqueous solution were charged and heated at 173°C under a nitrogen atmosphere while stirring. The temperature was raised over 5 hours until 27.300 kg of water was distilled out, and then the pot was sealed. DCB distilled azeotropically during dehydration was separated in a decanter and returned to the pot as needed. After the dehydration was completed, the anhydrous sodium sulfide composition was dispersed in the DCB inside the pot. After the above dehydration step was completed, the internal temperature was cooled to 160°C, 47.492 kg (479 mol) of NMP was charged, and the temperature was raised to 185°C. When the pressure reached 0.00 MPa, the valve connected to the rectification column was opened, and the internal temperature was raised to 200° C. over 1 hour. At this time, cooling and valve opening were controlled so that the temperature at the outlet of the rectifying column was 110° C. or less. The distilled mixed vapor of DCB and water was condensed in a condenser and separated in a decanter, and the DCB was returned to the pot. The amount of distilled water was 179 g. The internal temperature was raised from 200°C to 230°C over 3 hours and stirred for 1 hour, then the temperature was raised to 250°C and stirred for 1 hour. After the reaction was completed, the bottom valve of the autoclave was opened and the autoclave was flashed into a 150 L vacuum stirring dryer equipped with stirring blades to remove NMP, and the autoclave was cooled to room temperature. A crude PPS mixture with a solid content concentration of 55% was obtained.

[Example 1]
20 kg of the crude PPS mixture obtained in Synthesis Example 1 and 21 kg of methanol were placed in a stirring container, stirred and mixed at 25° C. for 30 minutes, and the slurry was filtered with a filter device, and further 32 kg of methanol was poured in several portions and filtered. The specific surface area was 95 m ² /g. The filtered cake was transferred to a steam stripping device (Ribocorn manufactured by Okawara Seisakusho Co., Ltd.), and stirred and mixed for 60 minutes while blowing steam at 11 kg/hr. As a result of analysis of the amount of methanol contained in the mixture after treatment, it was found to be 0.1%. 32 kg of carbonated water was poured into the mixture, and the mixture was stirred and mixed at 25° C. for 30 minutes. The obtained slurry was filtered using a filter device, and 42 kg of carbonated water was poured into the slurry in several portions and filtered. The COD concentration was measured using the filtered liquid phase component as wastewater. Table 1 shows the COD evaluation of the wastewater and the evaluation of the obtained porous PPS.

[Example 2]
The same procedure as in Example 1 was carried out except that the steam amount was 16 kg/hr and the steam flow rate was tripled. Analysis of the amount of methanol contained in the mixture after the steam stripping process revealed that it was 0.02%. Table 1 shows the COD evaluation of the wastewater obtained after the step of contacting with carbonated water and the evaluation of the obtained porous PPS.

[Example 3]
The same procedure as in Example 2 was carried out except that ethanol was used as the washing solvent. The specific surface area of the resin obtained after the contacting step with ethanol was 92 m ² /g. An analysis of the amount of ethanol contained in the mixture after the steam stripping process revealed that it was 0.03%. Table 1 shows the COD evaluation of the wastewater obtained after the step of contacting with carbonated water and the evaluation of the obtained porous PPS.

[Example 4]
The same procedure as in Example 2 was carried out except that isopropyl alcohol was used as the washing solvent. The specific surface area of the resin obtained after the contacting step with isopropyl alcohol was 90 m ² /g. The amount of isopropyl alcohol contained in the mixture after the steam stripping process was analyzed and found to be 0.04%. Table 1 shows the COD evaluation of the wastewater obtained after the step of contacting with carbonated water and the evaluation of the obtained porous PPS.

[Example 5]
The same procedure as in Example 2 was carried out except that acetone was used as the washing solvent. The specific surface area of PPS after the step of contacting with acetone was 88 m ² /g. The amount of acetone contained in the mixture after the steam stripping process was analyzed and found to be 0.03%. Table 1 shows the COD evaluation of the wastewater obtained after the step of contacting with carbonated water and the evaluation of the obtained porous PPS.

[Comparative example 1]
20 kg of the PPS mixture obtained in Synthesis Example 1 and 21 kg of methanol were placed in a stirring container, stirred and mixed at 25° C. for 30 minutes, and the slurry was filtered with a filtration device, and 32 kg of methanol was poured in several portions and filtered. The specific surface area was 95 m ² /g. The filtered cake was placed in a dryer to completely remove methanol. Analysis of the amount of methanol in the mixture after drying revealed that it was 0.1%. 32 kg of carbonated water was poured into the dried mixture, and the mixture was stirred and mixed at 25° C. for 30 minutes to obtain a slurry. The slurry was filtered using a filtration device, and 42 kg of carbonated water was poured into the slurry in several portions and filtered. The COD concentration was measured using the filtered liquid phase component as wastewater. Table 2 shows the COD evaluation of the wastewater and the evaluation of the obtained porous PPS.

[Comparative example 2]
It was carried out in the same manner as Comparative Example 1, and the cake produced by filtration was placed in a dryer to remove methanol. The amount of methanol contained in the mixture after drying was analyzed and found to be 3.2%. Table 2 shows the COD evaluation of the wastewater obtained after the step of contacting with carbonated water, which had a specific surface area of 8 m ² /g, and the evaluation of the obtained porous PPS.

[Comparative example 3]
20 kg of the PPS mixture obtained in Synthesis Example 1 and 21 kg of methanol were placed in a stirring container, stirred and mixed at 25° C. for 30 minutes, and the slurry was filtered with a filtration device, and 32 kg of methanol was poured in several portions and filtered. The specific surface area of PPS in the mixture was 95 m ² /g. 21 kg of water was poured into the filtered cake, stirred and mixed at 25° C. for 30 minutes, the slurry was filtered with a filter, and 21 kg of water was poured in several portions and filtered. The amount of methanol in the obtained resin was analyzed and found to be 4.4%. 32 kg of carbonated water was poured into the filtered cake, and the mixture was stirred and mixed at 25° C. for 30 minutes to obtain a slurry. The slurry was filtered using a filtration device, and 42 kg of carbonated water was poured into the slurry in several portions and filtered. The COD concentration was measured using the filtered liquid phase component as wastewater. Table 2 shows the COD evaluation of the wastewater and the evaluation of the obtained porous PPS.

[Comparative example 4]
The same procedure as in Example 1 was carried out except that the amount of steam was 1.1 kg/hr and the flow rate of steam was increased 0.2 times. An analysis of the amount of methanol contained in the mixture after the steam stripping process revealed that it was 30%. Table 2 shows the COD evaluation of the wastewater obtained after the step of contacting with carbonated water and the evaluation of the obtained porous PPS.

A comparison of Examples 1 to 5 and Comparative Examples 1 to 2 showed that PPS produced by removing the solvent using steam stripping had a larger specific surface area and a smaller amount of sodium. Furthermore, a comparison between Examples 1 to 5 and Comparative Example 3 showed that the COD concentration of wastewater can be reduced when steam stripping is used. Furthermore, a comparison between Examples 1 to 5 and Comparative Example 4 showed that the COD concentration of wastewater can be reduced when treated with a specific range of steam amount.

Claims

Step (1) of obtaining a mixture containing crude polyarylene sulfide by desolvating the crude reaction product containing polyarylene sulfide obtained by reacting a polyhaloaromatic compound and a sulfidating agent in an organic polar solvent. and,
A mixture containing crude polyarylene sulfide is brought into contact with water and a solvent containing an oxygen atom having 1 to 3 carbon atoms to form the crude polyarylene sulfide into porous particles having a specific surface area of 30 [m 2 /g] or more. Step (2) and
a step (3) of removing the oxygen atom-containing solvent from the mixture containing the porous particles;
a step (4) of bringing the obtained porous particles into contact with carbonated water,
The method for removing the solvent in step (3) is a steam stripping method, and the amount of steam is 50 parts by mass or more based on 100 parts by mass of the porous polyarylene sulfide particles. Method for purifying polyarylene sulfide.
The purification method according to claim 1, wherein in the step (3), the water content of the mixture after removing the solvent is 10 to 250 parts by mass based on 100 parts by mass of the mixture.
The purification method according to claim 1 or 2, wherein in the step (4), the porous particles of polyarylene sulfide and carbonated water are brought into contact under a pressure lower than 0.1 MPa.
The purification method according to any one of claims 1 and 2, wherein in the step (4), the porous particles of polyarylene sulfide and carbonated water are brought into contact at a temperature of 100°C or less.
The purification method according to claim 1 or 2, wherein the organic solvent is an alcohol solvent or a ketone solvent.
A method for producing polyarylene sulfide, comprising the step of purifying polyarylene sulfide by the purification method according to any one of claims 1 to 3.
7. The method for producing polyarylene sulfide according to claim 6, wherein the purified polyarylene sulfide is a porous particle having a specific surface area of 10 [ m2 /g] or more.