JPH04139215A - Method for washing polyarylene sulfide - Google Patents

Abstract

PURPOSE:To efficiently remove residual alkali metallic salts by washing a polyarylene sulfide prepared by reacting an alkali metal (hydro)sulfide with a dihalogen aromatic compound in a polar solvent according to a specific method. CONSTITUTION:An alkali metal (hydro)sulfide [preferably sodium (hydro)sulfide] is initially reacted with a dihalogen aromatic compound (preferably p- dichlorobenzene) in a polar solvent (preferably N-methyl-2-pyrrolidone) and produced polyarylene sulfide particles are then separated from the resultant reaction mixture. The above-mentioned particles are subsequently washed with an organic solvent (e.g. acetone), having a lower boiling point than that of water and compatible with the aforementioned polar solvent and water and then washed with water. Furthermore, the above-mentioned particles are preferably washed by a method for washing with the organic solvent and water as follows. The organic solvent or water in a stirrable amount is added and the aforementioned particles in a slurry form are slowly stirred.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention is directed to the production of polyarylene sulfide obtained by reacting an alkali metal sulfide and/or alkali metal hydrosulfide with a dihalogen aromatic compound in a polar solvent. Regarding cleaning method.

[Prior Art] Polyarylene sulfide (PAS) has N-
Methyl-2- and lolidone (NMP), etc.

It is produced by reacting a dihalogen aromatic compound with an alkali metal sulfide and/or an alkali metal hydrosulfide in a polar solvent.

When the reaction mixture obtained by the reaction in the production of PAS is filtered, particulate PAS is collected, and this PAS contains a polar solvent and by-produced alkali metal salts. Further, even when a drying operation is performed after filtration, the alkali metal salt a remains in the PAS. The alkali metal salts remaining in the PAS can cause product damage, decrease in mechanical performance such as tensile strength, and decrease in electrical properties such as resistance, so this should be removed after the PAS is finished. Is it necessary to remove alkali metal salts?

[Is it an invention or a problem to solve? In order to remove alkali metal salts from 1l PAS, in the case of particulate PAS obtained by filtering the reaction mixture, is it possible to immediately wash it with water? The cleaning solution is a mixture of polar solvents and water, and due to environmental concerns, it cannot be simply disposed of as wastewater.
Since polar solvents are generally expensive, it is necessary to separate them from water and reuse them. In this case, is distillation a possible method for separating the polar solvent and water?
Since polar solvents have a higher boiling point than wood, a polar solvent with dissolved alkali metal salts will be present at the bottom of the distillation column, which will require further separation.
It is also possible to consider extraction with a solvent that is soluble in polar solvents (for example, methylene chloride), but even in this case, a separation step between water and the extraction solvent is ultimately required.

On the other hand, in the case of particulate PAS obtained by further drying the reaction mixture after filtration, has it been proposed to wash it with ethylene glycol (JP-A-60-21061)?
Even in this case, the cleaning solution is a mixture of ethylene glycol, water, and alkali metal salts, and cannot be simply disposed of as waste water.When attempting to separate these by distillation, ethylene glycol is higher in water than water. Because of the boiling point, ethylene glycol with alkali metal salts dissolved therein will be present at the bottom of the distillation column, necessitating a separation step between the alkali metal salts and ethylene glycol.

As described above, the conventional PAS cleaning method has disadvantages in that processing of the cleaning solution is troublesome and, moreover, the removal rate of alkali metal salts is not sufficient.

The present invention has been made in view of the above circumstances, and provides a method for cleaning PAS, which can efficiently remove alkali metal salts remaining in PAS, and can simplify the processing process of cleaning liquid. The purpose is to

[Means and effects for solving the problems] In order to achieve the above object, the present invention provides, as a first invention, an alkali metal sulfide and/or an alkali metal hydrosulfide and a dihalogen aromatic compound in a polar solvent. When washing the polyarylene sulfide particles separated from the reaction mixture obtained by the reaction, after washing the polyarylene sulfide particles with an organic solvent that has a lower boiling point than water and is compatible with the above polar solvent and water. , provides a method for washing polyarylene sulfide characterized by washing with water.

In addition, the present invention provides, as a second invention, that when washing the polyarylene sulfide particles separated and dried from the reaction mixture, the polyarylene sulfide particles have a boiling point lower than that of water and are compatible with water. After washing with an organic solvent having or a mixed solvent of this organic solvent and water,
Provided is a method for cleaning polyarylene sulfide, which comprises washing with water whenever only an organic solvent is used, and if necessary, when a mixed solvent of an organic solvent and water is used.

The present invention will be explained in more detail below.

The PAS used for cleaning in the present invention is obtained by reacting a dihalogen aromatic compound with an alkaline earth sulfide and/or an alkali metal hydrosulfide in a polar solvent.

In this case, the type of the dihalogen aromatic compound, alkali metal sulfide, alkali metal hydrosulfide, or their polymerization operation may include, for example, those described below, or may be limited to these. There isn't.

(a) Dihalogen aromatic compound Examples of the halogen aromatic compound which is a raw material monomer include dihelobenzenes such as m-dihalobenzene and p-dihalobenzene; 2.3-dihatarotoluene, 2.5-
Dihalotoluene, 2.6-cyhalotoluene, 3.4-dihalotoluene, 2゜5-dihaloxylene, 1-ethyl-
2,5-dihalobenzene, l,2,4.5-tetramethyl-3,6-dihalobenzene, l-n-hexyl-
2,5-dihalobenzene, l-cyclohexyl-2,5
- Alkyl-substituted dihalobenzenes such as dihalobenzene or cycloalkyl-substituted dichlororonzenes: 1-phenyl-2,5-dihalobenzene, l-pencyl-2,5
- Aryl t* dihalobenzenes such as dihalobenzene and 1-P-tolyl-2,5-dihalobenzene; Dihalobiphenyls such as 4.4゜dihalobiphenyl: 1゜4-dihalonaphthalene, 1.6-dihalo Naphthalene, 2.6-
Dihalonaphthalenes such as dihalonaphthalene, 3,5-dihalobenzoic acid, 4,4'-dihalodiphenyl ether,
Examples thereof include 4,4'-dihalodiphenyl ether, 4,4'-dihalodiphenyl ketone, 4,4'-dihalodiphenyl sulfite, and 4,4'-dihalodiphenyl sulfoxide.

The two halogen elements in these dihalogen aromatic compounds are fluorine, chlorine, bromine, or iodine, and they may be the same or different from each other.

Among the dihalogen aromatic compounds, preferred are dihalobenzenes, particularly those containing p-dichlorobenzene as a main component.

These dihalogen aromatic compounds may be used alone or in combination of 2fa or more,
It may also be used in combination with other dihalogen aromatic compounds, such as dihalogen aromatic carboxylic acids and alkali metal salts thereof.

In addition, branching agents such as trihelobenzene, cyheroaniline, and dihalonitrobenzene, and molecular weight regulators such as monohelobenzene, thiophenol, phenol, and anisono can also be used as necessary.

(b) Alkali metal sulfide and alkali metal hydrosulfide As a sulfur source for PAS, alkali metal sulfide and/or alkali metal hydrosulfide (hereinafter, alkali metal sulfide and/or alkali metal hydrosulfide are simply referred to as alkali metal sulfides and/or alkali metal hydrosulfides) metal (water) sulfide) is used.

Examples of the alkali metal sulfide include:

Examples include lithium sulfide, sodium sulfide, potassium sulfide, rubidium sulfide, and cesium sulfide.

Among these, sodium chloride and lithium sulfide are preferable, and sodium sulfide is particularly preferable as the alkali metal hydrosulfide, for example, lithium hydrosulfide (LiH3), sodium hydrosulfide (NaH3),
Potassium bisulfide (NiH3), rubidium bisulfide (RbH)
5), calcium hydrosulfide (CaHS), cesium hydrosulfide (CsHS), etc.

Among these, sodium bisulfide and lithium bisulfide are preferred, and sodium bisulfide is particularly preferred.

These various alkali metal (water) sulfides may be used alone or in combination of two or more.

Furthermore, the alkali metal (water) sulfide may be obtained using hydrogen sulfide and an alkali metal hydroxide as raw materials.

In addition, these various alkali metal (water) sulfides can be used in the form of anhydrides, hydrates, aqueous solutions, or water-containing mixtures, or if hydrates, aqueous solutions, or water-containing mixtures are used, As described below, it may be necessary to perform a dehydration operation before the reaction.

(c) Polar Solvent Examples of polar solvents include organic amide compounds, lactam compounds, urea compounds, and cyclic organic phosphorus compounds. Specifically, N,N-dimethylformamide, N,N
-dimethylacetamide, N,N-diethylacetamide, N,N-dipropylacetamide, N,N-dimethylbenzoic acid amide, caprolactam, N-methylcaprolactam, N-ethylcaprolactam, N-isopropylcaprolactam, N-isobutylcaprolactam, N
-Normal propyl caprolactam, N-normal butyl caprolactam, N-cyclohexyl caprolactam, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, N-isopropyl-2-pyrrolidone, N-isobutyl-2-pyrrolidone, N-Normal propyl-2-
Pyrrolidone, N-n-n-butyl-2-pyrrolidone, N
-Cyclohexyl-2-pyrrolidone, N-methyl-3-methyl-2-pyrrolidone, N-cyclohexyl-2-pyrrolidone, N-ethyl-3-methyl-2-pyrrolidone, N
-methyl-3,4゜5-trimethyl-2-pyrrolidone,
N-methyl-2-piperitone, N-isopropyl-2-
piperitone, N-methyl-2-piperitone, N-ethyl-2-piperitone, N-isopropyl-2-doberitone, N-methyl-6-methyl-2-piperidone, N-methyl-3-ethyl-2-piperidone , tetramethylurea,
N,N'-dimethylethyleneurea, N,N''-dimethylpropyleneurea, l-methyl-1-oxosulfolane, l-ethyl-1-oxosulfolane, l-phenyl-
1-oxosulfolane, l-methyl-1-oxophosphorane, 1-normalpropyl-1-oxophosphorane,
and l-phenyl-1-oxophosphorane.

Each of these polar solvents may be used alone, or two polar solvents may be used.
A mixture of more than one species may be used.

Among the above various polar solvents, aprotic organic amides or lactams are preferred, and among these, N-
Alkyl lactams and N-alkylpyrrolidone are preferred, and N-methyl-2-pyrrolidone is particularly preferred.

(d) Polymerization aid If necessary, for example, lithium chloride is used as a polymerization aid.

The amount of lithium chloride used is usually in the range of 0.03 to 2.0 mol per mol of the alkali metal (water) sulfide,
It is preferably selected in the range of 0.1 to 1.6 mol. If the amount of lithium chloride is less than 0.03 mole, the molecular weight of the produced polymer may be low, or the content of impurities such as sodium chloride in the PAS particles may not be sufficiently reduced. If the amount exceeds 2.0 moles, the polymerization aid effect will not be exhibited in proportion to the amount, and lithium chloride may remain in the produced polymer at a high concentration, which is not preferable.

In addition, when lithium chloride is not used at all as a polymerization aid, or when a very small amount of lithium chloride is used, if lithium sulfide is used as the alkali metal sulfide of the raw material component, the lithium sulfide and dihalogen aromatic compound may react. The resulting lithium chloride acts as a polymerization aid.

In addition, as other polymerization aids, sodium acetate, lithium acetate, water, etc. can be used.

(e) Polymerization reaction operation In the polymerization reaction, a dihalogen aromatic compound and an alkali metal (water) sulfide are brought into contact with each other in a polar solvent, using a polymerization aid if necessary, to produce PAS.

In this case, the dihalogen aromatic compound and the alkali metal (water) sulfide preferably have a molar ratio of 0.75:1 to 2.0.
・l, more preferably a molar ratio of 0.9:1 to 1.2:l
Use the ratio of

The amount of polar solvent used is not particularly limited as long as it is sufficient for one reaction to proceed uniformly, and is usually 0.1 to 10 times the total weight of raw material components and polymerization aids. Selected based on weight range. If the amount is less than 0.1 times the weight, the reaction may be non-uniform, and if it exceeds 10 times the weight, the volumetric efficiency will be poor and the productivity will be lowered, which is not preferable.

Next, a preferred example of the reaction between the dihalogen aromatic compound and alkali metal (water) sulfide will be explained. First, a required amount of alkali metal (water) is added to a desired polar solvent.
After adding a sulfide and a polymerization aid if necessary, and performing a dehydration operation by azeotropic distillation, vacuum distillation, etc. if necessary, the required amount of dihalogen aromatic compound and various additives used as necessary. The components are added and heated to a temperature generally in the range of 180 to 330°C, preferably 220 to 300°C to carry out a polymerization reaction. If the reaction temperature is less than 180°C, the reaction rate is too slow to be practical, while if it exceeds 330°C, side reactions or deterioration of the produced polymer may occur, causing coloration or gelation.

The reaction time depends on the types and proportions of the raw materials used, the amount of polymerization auxiliary, etc., and can be roughly determined, usually within 20 hours, preferably within (ml ~
It takes about 8 hours.

This polymerization reaction can be carried out in an inert gas atmosphere such as nitrogen, argon, carbon dioxide, or water vapor, and there is no particular restriction on the reaction pressure, and it is usually from the autogenous pressure of the polymerization reaction system such as a solvent to 50% The reaction is carried out at pressures up to g/c2 (absolute pressure).

When using lithium chloride as a polymerization aid, if lithium chloride, alkali metal (water) WL compound, or both are in an aqueous solution, water-containing state, or hydrate, first add lithium chloride or alkali to a polar solvent. It is desirable to add a metal (water) sulfide and perform a dehydration operation such as azeotropic distillation or vacuum distillation to prepare a mixed solution, and then add a substantially anhydrous dihalogen aromatic compound thereto and react. When both lithium chloride and the alkali metal (water) sulfide as a raw material component are anhydrous, there is no particular restriction on the order of addition of each component into the polar solvent.The reaction may be a one-step reaction conducted at a steady temperature; A multistage reaction in which the temperature is increased stepwise may be used, or a reaction mode in which the temperature is gradually increased may be adopted.

The RAS particles can also be separated from the reaction mixture by filtration.

In this case, by filtering one reaction mixture, only granular PAS particles are collected on a sieve, and oligomers, polymerization aids, alkali metal salts, reaction impurities, polar solvents, water,
Collect the remaining solution consisting of unreacted scum etc. under the sieve.

A filter that can only filter out PAS particles usually has a filter size of 200
-5 meshes, preferably 100-16 meshes.

The present invention is for cleaning the PAS particles obtained as described above, and will be explained below separately into the first invention and the second invention.

In the first invention, the PAS particles separated from the reaction mixture are washed with an organic solvent that has a lower boiling point than water and is compatible with a polar solvent and wood, and then washed with water.

In this case, more specifically, it is preferable to take the following procedure.

(2) Pre-washing of PAS after filtration It is desirable to pre-wash PAS with a warm polar solvent. This is because, for example, when lithium chloride is used as a polymerization aid, lithium chloride is removed from the PAS in advance. This is because lithium chloride is expensive and it is preferable to collect and reuse it. However, preliminary cleaning is not necessarily required.

(2) Washing with an organic solvent By washing with an organic solvent, the polar solvent adhering to the PAS is washed and replaced with an organic solvent.

In this case, the organic solvent must have the following properties.

B. It must be compatible with polar solvents.

As a result, the polar solvent is effectively washed and replaced by the organic solvent.

Must be compatible with mouth and water.

In other words, PAS is porous, and on the 9th floor of
The organic solvent and alkali metal salt remaining in S mainly exist in the pores. Therefore, if the specific solvent is not compatible with the wood, the water washing described in (2) below will take a long time, and the organic solvent and alkali metal salt in the pores will not be sufficiently removed.

C. It must have a lower boiling point than water.

Thereby, as will be described later, the cleaning liquid can be separated into an organic solvent and water containing an alkali metal salt by distillation.

Examples of such organic solvents include acetone, methanol, ethanol, and isopropyl alcohol. One type of organic solvent may be used alone, or two or more types may be used in combination.

The cleaning method is not particularly limited, and any method used for particle cleaning may be used, or an amount of organic solvent (usually about 5 times the volume of PAS) that allows the PAS particles to be stirred into a slurry at room temperature and pressure. It is preferable to add and slowly stir.

■Separation and removal of organic solvents Next, the organic solvent is separated and removed from the RAS.

The organic solvent can be separated and removed by filtration using a 200-5 mesh filter, preferably 100-16 mesh filter, or by centrifugation. At this point, the organic solvent and alkali metal salt attached to the RAS remain.

■Repetition of the above operations (■) and (2) It is preferable to repeat the operations (2) and (2) above several times. As a general guideline, it is best to carry out the process until the remaining amount of polar solvent in PAS is about 1% by weight or less.

■ Washing with water Finally, wash this PAS with water. Washing with water removes adhering organic solvents and alkali metal salts.

The water washing method is not particularly limited, and any method used for particle washing may be used, or by adding an amount of water (usually about 5 times the volume of PAS) that can stir the PAS particles or slurry at room temperature and pressure. It is preferable to use a method of stirring slowly, and the number of times of washing with water may be selected as appropriate depending on the required value of the residual alkali metal salt.

■Processing of cleaning liquid The mixture of polar solvent and organic solvent that comes out of step (■) is separated by distillation, and both are reused.

(2) The mixture of water, organic solvent, and alkali metal salt that comes out is separated by distillation. At this time, since the organic solvent has a lower boiling point than water, it is distilled out from the top of the distillation column. Water containing dissolved alkali metal salts remains at the bottom of the tower and can be disposed of as waste water.

In the second invention, the PAS particles separated from the first reaction mixture are washed with an organic solvent that has a lower boiling point than wood and is compatible with water, or a mixed solvent of this organic solvent and water. After that, wash with water if necessary.

More specifically, it is preferable to take the following procedure.

(1) Pre-washing of PAS after filtration It is desirable to pre-wash RAS with a warm polar solvent as in the first invention, and the reason is also the same as in the first invention.

(2) Dry the dry PAS to remove the bipolar solvent. By drying, the step of separating the polar solvent and the organic solvent in 3 of the first invention can be omitted.6 The drying method is not particularly limited, or low temperature drying under reduced pressure is used to prevent deterioration of the polar solvent. Preferably, the polar solvent in the dried PAS is 2
It is desirable that it be below about 00 wtpp-.
If it exceeds 200 wtpp, it will mix with the polar solvent or organic solvent or organic solvent/water mixed solvent during washing with the primary organic solvent or organic solvent/water mixed solvent, and even in the distillation process of the washing liquid, it will be mixed with the water side at the bottom of the column. Therefore, it is necessary to separate water and polar solvent.

(3) Cleaning with an organic solvent or a mixed solvent of organic solvent/water Since the organic solvent in the second invention plays the role of making it easier for water to enter the pores of PAS, the properties required for the organic solvent are as follows: does not require compatibility with polar solvents, or is otherwise the same as the first invention.

As such organic solvents, the same ones mentioned in the first invention can be mentioned.

If a mixed solvent of organic solvent/water is used in this step,
Alkali metal salts are removed from PAS. In addition, by using a mixed solvent, when the organic solvent is separated from water and alkali metal salt in a later step, it is possible to reduce the amount of organic solvent that gets mixed into the water and alkali metal salt side. This has the advantage of simplifying the separation equipment.

In addition, in the mixed solvent of organic solvent/water, the mixing ratio is not particularly limited, or it is appropriate that the organic solvent be 20% by weight or more, particularly 30 to 80% by weight.

The cleaning method is not particularly limited, and any method used for particle cleaning may be used, or heating up to about 170°C and/or pressurization up to about 14 kg/cm2 may be used.
Amount of S particles or slurry that can be stirred (usually PA
It is preferable to add a solvent of about 5 times the volume of S and stir it.

(4) Separation and removal of organic solvent or mixed solvent This can be carried out by the same method as in the first invention.

At this point, when only organic solvent was used in (3), the organic solvent and alkali metal salt attached to PAS remained, and when a mixed solvent was used in (3), PAS
Some residual mixed solvent remains.

(5) Repeat the operations (3) and (4) above (3),
It is preferable to repeat the operation (4) several times.This allows the washing water to enter the pores of the PAS more easily when using only an organic solvent, and allows the washing water to enter the pores of the PAS more easily when using a mixed solvent. It can be removed better.

(6) Washing with water If an organic solvent is used in (3), be sure to wash with water.

As a result, the organic solvent and alkali metal salt adhering to the PAS are removed.

(3) If a mixed solvent is used, wash with water if necessary. This removes the adhering mixed solvent and the like.

Note that the same method as in the first invention can be used as the washing method.

(7) When only an organic solvent is used in processing (3) of the cleaning solution, the organic solvent that comes out in (4) is either an impurity or a trace amount.

It may be possible to reuse it as is, or if the amount of impurities has increased, it can be separated and removed by distillation or other methods. In addition, the mixed liquid of water, organic solvent, and alkali metal salt that came out in (6) is f
@1 Separation by distillation as in the invention. At this time, since the organic solvent has a lower boiling point than water, it is distilled out from the top of the distillation column. The water in which the alkali metal salts are dissolved remains at the bottom of the tower, and can be disposed of as wastewater.

When using a mixed solvent of organic solvent/water in (3), (4)
The mixture of water, organic solvent, and alkali metal salt that comes out is
Separate by distillation. At this time, the organic solvent is distilled off from the top of the distillation column in the same manner as above, and water in which the alkali metal salt is dissolved remains at the bottom of the column.

In addition, when washing with a mixed solvent and washing with water, the washing water for the first washing contains a certain amount of organic solvent, so it may be desirable to separate the organic solvent by distillation. and can be disposed of as wastewater.

[Examples] Next, the present invention will be specifically illustrated by Examples, but the present invention is not limited to the following Examples.

Sample I ILl of the sample in 12
! : 9.13Kg of sodium sulfide pentahydrate (
(54.3 mol), 2.3 g (54.3 mol) of lithium chloride and 30 g of N-methyl-2-pyrrolidone (NMP) were added, and water was distilled off under reduced pressure at 160°C. After that, NMPlO statement, p-dichlorobenzene 7.98K
g (54.3 mol) was added and reacted for 3 hours to obtain 1 reaction mixture.

The reaction mixture was cooled and filtered with granular polyphenylene sulfite (granular PP5) through a 140 mesh stainless steel sieve.
) was separated by filtration to separate granular PPS and its filtrate.Next, this granular PPS was washed with 20 parts of NMP.

Particulate PPS was separated using a 140-mesh stainless steel sieve washed with NMP e1'. After this separation, a part of the wet granular PPS was collected and used as a sample in Examples.

This sample I consists of PP5200g, NMP240g,
It consisted of 0.6g of sodium chloride.

1000 g of acetone was added to the above sample (2) and gently stirred for about 30 minutes. Thereafter, one particle of PPS and a liquid were separated using a 24-mesh sieve. This granular PP
Add 1000g of acetone to S again, and slowly add about 3
After stirring for 0 minutes, pass through a 24-mesh sieve in the same way.
It was separated into granular PPS and liquid. In addition, acetone washing and separation were carried out in a similar manner.

The remaining NMP concentration in the granular PPS obtained here is:

It was 0.66wt$.

The separated liquid consisting of acetone/NMP resulting from this acetone washing and separation operation was fractionated into acetone and NMP by distillation, and both could be reused.

Add 1000g of water to the granular PPS that has been washed and separated with acetone.
was added and gently stirred for about 30 minutes. After that, 2
The granular PPS and liquid were separated using a 4-mesh sieve. When this water washing operation was carried out two more times, the amount of residual salt in the obtained granular PPS was 66pp-
There was. The separated liquid consisting of water/acetone/sodium chloride resulting from this water washing operation was separated into water/sodium chloride acetone by distillation. The acetone was reused, and the water containing sodium chloride was directly disposed of as wastewater.

Example 1 was repeated except that mN2 acetone was replaced with methanol.

Residual NMP in granular PPS obtained by methanol washing
The concentration was 0.66 wt$, and the amount of residual salt in the granular PPS obtained by washing with water was 38 ppm in Na value.

The sample I was heated under reduced pressure (40 Torr) for 12 hours.
It was dried at 0°C to obtain dry granular PPS (sample ■).

The NMPi degree in this dry granular pps is 120wt.
The ppH and residual salt amount were 3300 ppm in terms of Na'' value.The dried granules were made into pp 5ftppps-■.

The same operation was performed until the NMP concentration was 180wtpp.
m, dry granular p with residual salt content of 3400 ppm Na” value
ps'1tpps-■, residual NMP concentration is 150wt P
Dry granular pps with a residual salt amount or Na'' value of 1,400 ppm was defined as pps-■.

Example 3 In a closed container, 1000 g of methanol was added to PP5-■, and the mixture was gently stirred at 140°C for about 30 minutes. After that, the temperature was lowered to room temperature and granulated P was passed through a 24-mesh sieve.
It was separated into PS and liquid. This granular PPS was transferred to a closed container again, methanol looog was added thereto, and the mixture was heated to 140°C.
After stirring gently for about 30 minutes, granular PP
It was separated into S and liquid.

Next, the same water washing operation as in Example 1 was carried out twice. The amount of residual salt in the obtained granular PPS was 190 p in terms of Na" value.
It was p■.

The separated liquid was separated into water/sodium chloride methanol by distillation. The methanol was reused, and the water containing sodium chloride was directly disposed of as wastewater.

Examples 4-14. Comparative Examples 1 to 3 RAS-■ in the same manner as in Example 3, except that the solvent washing and water washing conditions were changed as shown in Table 1.

The cleaning steps ① and ② were carried out. The results are also listed in Table 1. Note that the amount of solvent, amount of water, and other operations used in the -times of washing were the same as in Example 3. However, in Example 11, the solvent cleaning was carried out under nitrogen pressure of 8.5 Kg/cm2·G.

[Hereinafter, blank spaces] Table 1 [Effects of the Invention] As explained above, the cleaning method of the present invention can effectively remove alkali metal salts contained in polyarylene sulfide, and therefore remove residual alkali metal salts. At a low concentration, it is possible to obtain polyarylene sulfide that is difficult to form due to a decrease in mechanical performance and electrical properties, and it is also possible to simplify the treatment process of the cleaning solution.

Claims (4)

[Claims] (1) When cleaning polyarylene sulfide particles separated from a reaction mixture obtained by reacting an alkali metal sulfide and/or alkali metal hydrosulfide with a dihalogen aromatic compound in a polar solvent, the polyarylene sulfide particles are washed. A method for washing polyarylene sulfide, which comprises washing with an organic solvent having a boiling point lower than that of water and having compatibility with the polar solvent and water, and then washing with water. (2) When washing polyarylene sulfide particles that have been separated and dried from the reaction mixture obtained by reacting an alkali metal sulfide and/or alkali metal hydrosulfide with a dihalogen aromatic compound in a polar solvent, A method for washing polyarylene sulfide, which comprises washing polyarylene sulfide particles with an organic solvent having a lower boiling point than water and having compatibility with water, and then washing with water. (3) When washing polyarylene sulfide particles that have been separated and dried from the reaction mixture obtained by reacting an alkali metal sulfide and/or alkali metal hydrosulfide with a dihalogen aromatic compound in a polar solvent, A method for cleaning polyarylene sulfide, which comprises cleaning polyarylene sulfide particles with a mixed solvent of water and an organic solvent that has a lower boiling point than water and is compatible with water. (4) The method for cleaning polyarylene sulfide according to claim 3, characterized in that the polyarylene sulfide particles are washed with water after being washed with a mixed solvent.