JP7318843B1 - Method for purifying and producing polyarylene sulfide - Google Patents

Abstract

To provide a method for purifying and producing a porous polyarylene sulfide (PAS) having a large specific surface area and reduced COD of waste water. More specifically, the step (1) of obtaining a mixture containing crude PAS by removing the solvent from the crude reaction product containing PAS obtained by reacting a polyhaloaromatic compound with a sulfidating agent in an organic polar solvent. and a step (2) of contacting the mixture with water and an oxygen atom-containing solvent having 1 to 3 carbon atoms to turn the crude PAS into porous particles having a specific surface area of 30 [m / g] or more; a step (3) of removing the oxygen atom-containing solvent from the mixture containing the porous particles; and a step (4) of contacting the obtained porous particles with carbonated water, wherein the solvent in the step (3) A method for purifying and producing PAS, wherein the method for removing is a steam stripping method, and the amount of steam is 50 parts by mass or more with respect to 100 parts by mass of the porous particles of PAS. [Selection figure] None

Description

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

Polyarylene sulfide (hereinafter sometimes abbreviated as PAS) represented by polyphenylene sulfide (hereinafter sometimes abbreviated as PPS) is excellent in heat resistance, chemical resistance, etc., and is used in electric and electronic parts, automobile parts, Widely used for water heater parts, textiles, films, etc. Among them, the PAS porous material is used for chemical filtration for removing impurities in semiconductor manufacturing, and for filtering synthetic raw materials and organic solvents in pharmaceutical manufacturing, food manufacturing, and industrial chemical product manufacturing, taking advantage of its excellent heat resistance and chemical resistance. It is expected to be used for

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

Also known is a method of making PAS porous by contacting it with a specific organic solvent and then with water after polymerization of PAS (see Patent Document 2). However, the 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 burden of wastewater is a problem. rice field.

JP-A-2-163126 JP 2021-98815 A

Therefore, the problem to be solved by the present invention is to provide a purification method for porous PAS with a large specific surface area and reduced COD in wastewater, and a method for producing porous PAS with a large specific surface area and reduced COD in wastewater. to do.

As a result of various investigations by the present inventors, the mixture containing crude PAS was brought into contact with a specific organic solvent, and after being made porous by contacting with water, the specific organic solvent was removed using a steam stripping method. is removed, and then the porous PAS is contacted with water and carbon dioxide gas or carbonated water to obtain a porous PAS with a larger specific surface area and a reduced COD of wastewater than the conventional method. The present inventors have found that it is possible to achieve the present invention.

That is, the present disclosure provides a step of obtaining a mixture containing crude PAS by desolvating a crude reaction product containing PAS obtained by reacting a polyhaloaromatic compound with a sulfidating agent in an organic polar solvent ( 1) and
A step (2) of contacting a mixture containing crude PAS with water and an oxygen atom-containing solvent having 1 to 3 carbon atoms to convert 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;
and a step (4) of contacting the obtained porous particles with carbonated water,
The 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 with respect to 100 parts by mass of the PAS porous particles. It relates 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 refining porous PAS with a large specific surface area and reduced COD in wastewater, and a method for producing porous PAS with a large specific surface area and reduced COD in wastewater.

An embodiment of the present disclosure will be described in detail below, but the scope of the present disclosure is not limited to the embodiment described here, and various modifications can be made without departing from the scope of the present disclosure. In addition, when multiple upper and lower limits are described for a specific parameter, any upper and lower limits among these upper and lower limits may be combined to form a preferred numerical range. can.

One embodiment of the present disclosure relates to a method for purifying PAS. That is, the invention relating to the method for purifying PAS is a method for purifying crude PAS by desolvating a crude reaction product containing PAS obtained by reacting a polyhaloaromatic compound with a sulfidating agent in an organic polar solvent. ^a step (1) of obtaining a mixture containing The step (2) of forming porous particles, the step (3) of removing the oxygen atom-containing solvent from the mixture containing the porous particles, and the step (4) of contacting the obtained porous particles with carbonated water ), the 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 with respect to 100 parts by mass of the PAS porous particles; characterized by Details are given below.

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

PAS is usually prepared by reacting at least one polyhaloaromatic compound and at least one sulfidation agent under suitable polymerization conditions in an organic polar solvent typified by N-methyl-2-pyrrolidone. 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, specifically p-dichlorobenzene, o- Dichlorobenzene, m-dichlorobenzene, trichlorobenzene, tetrachlorobenzene, dibrombenzene, diiodobenzene, tribrombenzene, dibromnaphthalene, triiodobenzene, dichlorodiphenylbenzene, dibromodiphenylbenzene, dichlorobenzophenone , dibromobenzophenone, dichlorodiphenyl ether, dibromodiphenyl ether, dichlorodiphenyl sulfide, dibromodiphenyl sulfide, dichlorobiphenyl, dibromobiphenyl and the like, and mixtures thereof, and these compounds are block covalent. may be polymerized. Among these, dihalogenated benzenes are preferred, and those containing 80 mol % or more of p-dichlorobenzene are particularly preferred.

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

Furthermore, polyhaloaromatic compounds having functional groups with active hydrogen such as amino groups, thiol groups, and hydroxyl groups can be mentioned. Specifically, 2,6-dichloroaniline and 2,5-dichloroaniline. , 2,4-dichloroaniline, 2,3-dichloroaniline and other dihaloanilines; 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 and compounds in which an amino group is replaced with a thiol group or a hydroxyl group in a mixture thereof.

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

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

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; 3,3′-dinitro-4,4′-dichlorodiphenyl sulfones such as dihalonitrodiphenyl sulfones; 2,5-dichloro-3-nitropyridine, 2-chloro-3,5 - mono- or dihalonitropyridines such as dinitropyridine; or various dihalonitronaphthalenes.

Sulfidating agents for use 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 as aqueous mixtures or as anhydrates. Alkali metal sulfides can also be derived from the reaction between alkali metal hydrosulfides and alkali metal hydroxides.

In addition, a small amount of alkali metal hydroxide may be added in order to react with alkali metal hydrosulfide and alkali metal thiosulfate, which are usually present in trace amounts in 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, ε-caprolactam , hexamethylphosphoramide, tetramethylurea, N-dimethylpropyleneurea, amidourea of 1,3-dimethyl-2-imidazolidinoic acid, and lactams; sulfolane such as sulfolane and dimethylsulfolane; nitriles; ketones such as methyl phenyl ketone and mixtures thereof.

In the presence of these organic polar solvents, the conditions for polymerizing the sulfidating agent and the polyhaloaromatic compound are generally a temperature of 200 to 330° C. and a pressure of substantially The pressure should be in the range of 0.1 to 20 MPa, preferably 0.1 to 2 MPa. The reaction time varies depending on the temperature and pressure, but generally ranges from 10 minutes to 72 hours, preferably from 1 hour to 48 hours.

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

In the present disclosure, the PAS-containing crude reaction product obtained by the polymerization reaction is treated by an appropriate means (e.g., vacuum distillation method, centrifugal separation method, screw decanter method, vacuum filtration method, pressure filtration method, etc.). can be selected) to obtain a mixture containing crude PAS after separating off the organic polar solvent. At that time, the degree of separation and removal of the organic polar solvent is not particularly limited, but the ratio of solid content in the mixture (solid content concentration) is preferably 40 parts by mass or more, more preferably 100 parts by mass of the mixture. 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 still more preferably 99 parts by mass or less.

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

Examples of the oxygen atom-containing solvent having 1 to 3 carbon atoms to be brought into contact with the mixture containing crude PAS include at least one selected from the group consisting of alcohol solvents and ketone solvents. Examples of alcohol solvents (also referred to as alcohol 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 illustrated as a ketone solvent (also called a ketone solvent). In the present disclosure, monohydric alcohols containing up to 3 carbon atoms are preferred. Alternatively, this step may be carried out after reducing the concentration of an aqueous solution obtained by adding water to an oxygen atom-containing solvent having 1 to 3 carbon atoms.

The temperature at which the oxygen atom-containing solvent having 1 to 3 carbon atoms is added is not particularly limited. Range. Although the amount of the solvent used for one washing is not particularly limited, it is preferably 20 parts by mass or more, more preferably 50 parts by mass or more, and still more preferably 100 parts by mass or more with respect to 100 parts by mass of PAS. Therefore, it is preferably 5000 parts by mass or less, more preferably 1800 parts by mass or less, and still more preferably 600 parts by mass or less.

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

Step (3)
The purification method according to this embodiment subsequently has 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 known devices and methods can be used. That is, the mixture containing the porous particles is brought into contact with steam, and the volatile substances such as the oxygen atom-containing solvent contained in the mixture are volatilized and removed together with the steam. For example, an apparatus for stirring the mixture with a stirrer while supplying steam (for example, JP-A-4-292604), and an apparatus for supplying steam to the mixture from the bottom and contacting it in a multistage column in countercurrent flow (for example, Japanese Patent Publication No. 58-44086, Japanese Patent Application Laid-Open No. 2018-58025, etc.), a vertical apparatus in which a steam nozzle is arranged below the liquid surface of the mixture (for example, Japanese Patent Application Laid-Open No. 9-220402, etc.), and the like.

The conditions for steam stripping are not particularly limited. Part by mass or more is 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 removed efficiently. Also, for example, the temperature at which the steam is brought into contact 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 the steam is brought into contact is preferably 0.5 MPa or less, more preferably 0.3 MPa or less, and still more preferably atmospheric pressure or less. The steam may be blown from the bottom of the device, from the sides of the device, or from multiple points at the same time. Alternatively, the mixture containing the porous particles may be mixed in a pipe supplying the apparatus and then introduced into the evaporation tank.

In this step, the mixture after removing the oxygen atom-containing solvent by steam stripping contains steam-derived water. 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. From the viewpoint of cleaning efficiency in step (4), it is preferably 250 parts by mass or less, more preferably 200 parts by mass or less.

The volatile substances separated by the steam stripping treatment in this step may contain unreacted raw materials, organic polar solvents, PAS oligomers, by-products, etc., in addition to the oxygen atom-containing solvent. These materials may be further separated and recovered from the volatile material and reused in the production of another PAS.

Step (4)
The purification method according to the present embodiment subsequently has 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. Below, the range is more preferably up to 80° C. and the pressure (gauge pressure) is less than 0.1 MPa, preferably 0.05 MPa or less, and more preferably atmospheric pressure.

The amount of carbonated water to be used when contacting the porous particles is not particularly limited, but the contact between the porous particles and the carbonated water is excellent, and the purification efficiency is further improved. With respect to 100 parts by mass, preferably 50 parts by mass or more, more preferably 100 parts by mass or more, more preferably 200 parts by mass or more, preferably 10000 parts by mass or less, more preferably 5000 parts by mass or less, still more preferably 2000 parts by mass It is in the range of parts by mass or less.

Another embodiment of the present disclosure relates to a method for producing PAS, which includes a step of purifying PAS by the above purification method. That is, the invention relating to the method for producing the PAS is obtained by reacting a polyhaloaromatic compound with a sulfidating agent in an organic polar solvent, and desolvating a crude reaction product containing PAS to obtain the crude PAS. a step (1) of obtaining a mixture comprising
A step (2) of contacting a mixture containing crude PAS with water and an oxygen atom-containing solvent having 1 to 3 carbon atoms to convert 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;
and a step (4) of contacting the obtained porous particles with carbonated water,
The method for removing the solvent in step (3) is steam stripping.

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

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

PAS obtained through the above-described purification method or production method of the present disclosure (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, preferably 180 [m 2 /g] or more. m ² /g] or less, more preferably 150 [m ² /g] or less. In addition, a specific surface area can be measured by the method of an Example.

In addition, 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. The amount of sodium can be measured by the method of Examples.

The PAS obtained through the purification method or production method of the present disclosure can be used as it is for various molding materials, etc., as in the past, 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 for various molding materials. The temperature of this heat treatment varies depending on the treatment time and the atmosphere in which the treatment is performed, so it cannot be categorically defined, but it is usually preferable to perform the treatment at 180° C. or higher. If the heat treatment temperature is less than 180°C, the thickening speed is very slow and the productivity is poor, which is not preferable. The heat treatment may be carried out in a molten state at a temperature higher than the melting point of the polymer using an extruder or the like. However, considering the possibility of deterioration of the polymer, workability, etc., it is preferable to carry out at a temperature of 100° C. or less plus the melting point.

As in the past, the PAS obtained by the present disclosure can be mixed with fillers and other resins, melt-kneaded, directly or once molded into pellets, and then variously injection-molded, extrusion-molded, compression-molded, and blow-molded. By melt processing, a molded article having excellent heat resistance, molding processability, dimensional stability, etc. can be obtained. However, in order to further improve properties such as strength, heat resistance and dimensional stability, it is also possible to use various fillers in combination within a range that does not impair the object of the present invention. Examples of fillers include fibrous fillers and inorganic fillers. In addition, a small amount of release agent, colorant, heat stabilizer, ultraviolet stabilizer, foaming agent, rust preventive, flame retardant, lubricant, cup may be used as an additive during molding within the scope of the purpose of the present invention. A ring agent can be included. Further, synthetic resins and elastomers as described below 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, Polyethylene difluoride, polystyrene, ABS resins, epoxy resins, silicone resins, phenol resins, urethane resins, liquid crystal polymers and the like can be mentioned, and elastomers can include polyolefin rubbers, fluororubbers, silicone rubbers and the like.

Molded articles obtained by melt-molding the PAS obtained by the present disclosure or the resin composition containing it have excellent heat resistance, dimensional stability, etc. similar to PAS obtained by conventional methods. Electrical and electronic parts such as sealed molded products, automobile parts such as lamp reflectors and various electrical parts, interior materials for various buildings, aircraft and automobiles, precision parts such as OA equipment parts, camera parts, watch parts, etc. It can be widely used as injection-molded or compression-molded products, or extrusion-molded or pultrusion-molded products such as fibers, films, sheets, and pipes. It is also suitable for adsorbents, filtering agents, catalyst carriers, etc., taking advantage of its porosity.

Examples and comparative examples will be described below, but the present disclosure is not limited to these examples. In the following, unless otherwise specified, "%" and "parts" are based on mass.

〔evaluation〕

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

(2) Measurement of sodium content 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 the extent that it was immersed. It was completely incinerated with a microwave incinerator manufactured by Stone General Co., Ltd. 1% hydrochloric acid and pure water were added to dissolve the ash, the solution was analyzed for sodium content using an atomic absorption photometer, and the sodium content in the PPS was quantified from the obtained value. Pure water with a conductivity of 18.2 MΩ·cm was used in this operation.

(3) Measurement of specific surface area (BET specific surface area) The specific surface area of PPS was measured using Tristar II3020 manufactured by Shimadzu Corporation. The PPS obtained in Examples 1 to 5 and Comparative Examples 1 to 4 was placed in a cell, degassed, replaced with helium, cooled to −196° C., and 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, the liquid phase component obtained by filtration was used as wastewater to measure COD. 10 mL of waste water was collected, water was added to make 100 mL, 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, and then filtered. 10 mL of an aqueous potassium manganate solution (5 mmol/L) was added and heated in a boiling water bath for 30 minutes. After heating, 10 mL of an aqueous sodium oxalate solution (12.5 mmol/L) was added, and the COD of the wastewater was obtained by titration with an aqueous potassium permanganate solution (5 mmol/L) while maintaining the temperature at 60°C. Evaluation was performed according to the following criteria.
○: COD value of wastewater is less than 300 mg/L ×: COD value of wastewater is 300 mg/L or more

[Synthesis Example 1] Polymerization process of PPS Into a 150 L autoclave equipped with a stirring blade connecting a pressure gauge, a thermometer, a condenser, a decanter and a rectification tower, 33.222 kg (226 mol) of p-dichlorobenzene (hereinafter abbreviated as DCB), NMP2 280 kg (23 mol), 27.300 kg (230 mol as NaSH) of 47.23 wt% aqueous NaSH solution, and 18.533 g (228 mol as NaOH) of 49.21 wt% aqueous NaOH solution were charged and heated to 173°C under a nitrogen atmosphere while stirring. After the temperature was raised over 5 hours to distill 27.300 kg of water, the kettle was sealed. DCB azeotropically distilled during dehydration was separated with a decanter and returned to the kettle as needed. After dehydration, the anhydrous sodium sulfide composition was dispersed in DCB in the kettle. After completion of the dehydration step, 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 connecting the rectifying columns 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 outlet temperature of the rectifying column was 110° C. or lower. The mixed vapor of distilled DCB and water was condensed in a condenser, separated in a decanter, and DCB was returned to the boiler. The amount of distilled water was 179 g. The internal temperature was raised from 200° C. to 230° C. over 3 hours, stirred for 1 hour, then heated to 250° C. and stirred for 1 hour. After completion of the reaction, the bottom valve of the autoclave was opened and the autoclave was flushed into a 150 L vacuum stirring dryer equipped with stirring blades to remove NMP and cooled to room temperature. A crude PPS mixture with a solids 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 vessel and stirred and mixed at 25° C. for 30 minutes. The specific surface area was 95 m ² /g. The filtered cake was transferred to a steam stripping device (Ribocone manufactured by Okawara Seisakusho Co., Ltd.), and stirred and mixed for 60 minutes while blowing steam at 11 kg/hr. As a result of analyzing the amount of methanol contained in the treated mixture, it was 0.1%. 32 kg of carbonated water was poured into the mixture and stirred and mixed at 25° C. for 30 minutes. The resulting slurry was filtered with a filtering device, and 42 kg of carbonated water was poured in several portions and filtered. The COD concentration was measured by using the filtered liquid phase component as waste water. Table 1 shows the COD evaluation of the waste water and the evaluation of the obtained porous PPS.

[Example 2]
The procedure was carried out in the same manner as in Example 1 except that the amount of steam was increased to 16 kg/hr and the steam flow rate was tripled. As a result of analyzing the amount of methanol contained in the mixture after the steam stripping treatment, 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 procedure was carried out in the same manner as in Example 2, except that ethanol was used as the washing solvent. The specific surface area of the resin obtained after the step of contacting with ethanol was 92 m ² /g. As a result of analyzing the amount of ethanol contained in the mixture after the steam stripping treatment, 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 procedure was carried out in the same manner as in Example 2, except that isopropyl alcohol was used as the washing solvent. The specific surface area of the resin obtained after the step of contacting with isopropyl alcohol was 90 m ² /g. The amount of isopropyl alcohol contained in the mixture after steam stripping 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]
It was carried out in the same manner as in Example 2, except that acetone was used as the washing solvent. The specific surface area of the PPS after the step of contacting with acetone was 88 m ² /g. As a result of analyzing the amount of acetone contained in the mixture after the steam stripping treatment, 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.

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

[Comparative Example 2]
The cake was filtered in the same manner as in Comparative Example 1, and the resulting cake was placed in a dryer to remove methanol. As a result of analyzing the amount of methanol contained in the mixture after drying, it was 3.2%. Table 2 shows the COD evaluation of the wastewater obtained after the step of contacting with carbonated water having 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 vessel and stirred and mixed at 25° C. for 30 minutes. 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 filtering device, 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 mixed with stirring at 25° C. for 30 minutes to obtain a slurry. The slurry was filtered with a filtering device, and 42 kg of carbonated water was poured in several portions and filtered. The COD concentration was measured by using the filtered liquid phase component as waste water. Table 2 shows the COD evaluation of the wastewater and the evaluation of the obtained porous PPS.

[Comparative Example 4]
The procedure of Example 1 was repeated except that the amount of steam was changed to 1.1 kg/hr and the steam flow rate was changed to 0.2 times. Analysis of the amount of methanol contained in the mixture after the steam stripping treatment showed 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 1-5 and Comparative Examples 1-2 showed that the PPS produced by solvent removal using steam stripping had a higher specific surface area and a lower sodium content. Further, 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. Further, comparison between Examples 1 to 5 and Comparative Example 4 showed that the COD concentration of the wastewater can be reduced when the treatment is performed with the amount of steam within a specific range.

Claims (6)

Step (1) of obtaining a mixture containing crude polyarylene sulfide by desolvating a crude reaction product containing polyarylene sulfide obtained by reacting a polyhaloaromatic compound with a sulfidating agent in an organic polar solvent. and,
A mixture containing crude polyarylene sulfide is brought into contact with water and an oxygen atom-containing solvent having 1 to 3 carbon atoms to convert the crude polyarylene sulfide into porous particles having a specific surface area of 30 [m ² /g] or more. a step (2);
a step (3) of removing the oxygen atom-containing solvent from the mixture containing the porous particles;
and a step (4) of contacting the obtained porous particles with carbonated water,
The method for removing the solvent in the step (3) is a steam stripping method, and the amount of steam is 50 parts by mass or more with respect to 100 parts by mass of the polyarylene sulfide porous particles. A method for purifying polyarylene sulfide. 2. The purification method according to claim 1, wherein in the step (3), the water content of the mixture after removing the solvent is 10 parts by mass or more per 100 parts by mass of the mixture. 3. The purification method according to claim 1, wherein in the step (4), the polyarylene sulfide porous particles and carbonated water are brought into contact under a pressure lower than 0.1 MPa. 3. The purification method according to claim 1, wherein in the step (4), the polyarylene sulfide porous particles and carbonated water are brought into contact at a temperature of 100[deg.] C. or less. 3. A method for producing polyarylene sulfide, comprising a step of purifying polyarylene sulfide by the purification method according to claim 1 or 2 . 6. The method for producing polyarylene sulfide according to claim 5 , wherein the purified polyarylene sulfide is porous particles having a specific surface area of 10 [m ² /g] or more.