JPH0710997A - Production of granular polyphenylene sulfide having crushing resistance - Google Patents

Abstract

PURPOSE:To provide the subject production process. CONSTITUTION:This production process comprises subjecting a mixture containing a polyphenylene sulfide, a polar organic solvent and a phase separating agent, the polyphenylene sulfide being in a phase-separated state in which a thin solution phase and a thick solution phase coexist, to a treatment to evaporate at least part of the polar organic solvent and/or the phase separating agent and cooling the mixture to a temperature at which the thick solution phase is solidified or below.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing granular polyphenylene sulfide. More specifically, it relates to a method for producing granular polyphenylene sulfide having excellent crush resistance, which is excellent in post-treatment workability after completion of polymerization and handleability during melt processing.

[0002]

2. Description of the Related Art Polyphenylene sulfide (hereinafter referred to as PP
(Abbreviated as S) is an engineering plastic that has excellent heat resistance, mechanical properties, chemical resistance, oil resistance, hot water resistance, etc., and is used as a material for various molded products such as fibers, sheets, films, and electricity. It is used in a wide range of fields such as the electronic field, automobile field, and mechanical / precision machine field.
A typical method for producing PPS is disclosed in JP-B-45-3368. However, P produced by this method
Since PS has a low degree of polymerization, it was difficult to form PS into a film, sheet, fiber or the like. Further, the PPS obtained by this method is in the form of fine powder, and it is difficult to handle it in the post-treatment step, processing step after polymerization and the like.

Various improved polymerization methods have been proposed for the purpose of obtaining PPS having a high degree of polymerization. As the most typical method, there is a method disclosed in Japanese Patent Publication No. 52-12240, in which an alkali metal carboxylate is added to a reaction system as a polymerization aid. High polymerization linear P
Besides the fact that PS is obtained, what is noteworthy in these methods is that PPS is obtained in the form of granules having an average particle diameter of several hundreds of microns. By obtaining PPS in a granular form,
The post-treatment process and processing process become very easy. However, in the method disclosed in Japanese Patent Publication No. 52-12240, it is necessary to use a large amount of expensive polymerization aid such as lithium acetate or sodium benzoate in order to obtain PPS having a high degree of polymerization. is there. Therefore, the manufacturing cost increases, which is industrially disadvantageous. Further, according to this method, organic acid may be mixed into the treated wastewater, which may cause pollution.

As a further improved polymerization method, Japanese Patent Publication Sho 6
The method disclosed in, for example, JP-A-3-33775 can be mentioned. In these methods, the amount of coexisting water and the reaction temperature are remarkably changed between the pre-polymerization stage and the post-polymerization stage among various polymerization conditions. By this method, extremely high-molecular weight granular PPS can be produced inexpensively without using a polymerization aid. JP-B-52-12240 and JP-B-63-3377
As a drawback common to the methods disclosed in Japanese Patent Publication No. 5 etc., when these methods are applied to the production of low polymerization degree PPS used for sealing electronic / electrical parts, etc., they are fine and easily crushed. It can be mentioned that only PPS can be obtained. The obtained PPS is further miniaturized in the post-treatment process and the processing process, and is difficult to handle.

[0005]

DISCLOSURE OF THE INVENTION It is an object of the present invention to find a method for producing granular PPS which has a granular shape suitable for handling and is difficult to be crushed in a post-treatment step, a processing step and the like. did.

The inventors of the present invention have extensively studied the PPS polymerization methods disclosed in JP-B-52-12240 and JP-B-63-33775, and as a result, in these methods, (1) ) The generated PPS is dissolved in the polymerization solvent, and a state in which a phase having a high concentration of PPS and a phase having a low concentration of PPS coexist, that is, a phase separation state appears. The PPS concentrated phase is solidified in the cooling process and fixed as granular PPS, and (3) when the PPS having a low polymerization degree is produced, the solidified PPS concentrated phase is stirred by the stirring power in the cooling process. It was found that it was crushed and further miniaturized.

In order to obtain PPS particles in which PPS having a low degree of polymerization does not easily become fine, a polar organic solvent and a polar organic solvent are added from the polymerization mixture in the phase separation state (usually at high temperature and high pressure). And / or evaporating at least a portion of the phase separation agent to increase the temperature of the polymerization mixture to P
It has been found that it is effective to rapidly solidify the PPS concentrated phase by rapidly cooling it to a temperature below the temperature at which the PS concentrated phase solidifies, and the present invention has been reached.

[0008]

Thus, in the present invention, a mixture containing polyphenylene sulfide, a polar organic solvent and a phase separating agent, wherein the polyphenylene sulfide is in a phase separated state in which a dilute solution phase and a concentrated solution phase coexist. (A mixture containing at least the above three components is referred to as a PPS mixture hereinafter), and at least a part of the polar organic solvent and / or the phase separating agent is evaporated to obtain the P
Provided is a method for producing granular polyphenylene sulfide that is resistant to pulverization (that is, has crush resistance), which is characterized by cooling the temperature of the PS mixture to a temperature below the temperature at which the dense phase solidifies.

The present invention will be described in more detail below. (PPS mixture) The PPS mixture that is the subject of the present invention is P
Includes PS, polar organic solvent and phase separation agent. PPS is
General formula -Ph-S- (Ph shows a phenylene group,
S is a polymer containing a phenylene sulfide repeating unit represented by S), and a polymer containing 50 mol% or more of p-phenylene sulfide units is preferable.

The polar organic solvent in the present invention means PPS.
Is a solvent capable of dissolving N-methyl-2-pyrrolidone (hereinafter referred to as NMP), N-ethyl-2-pyrrolidone, pyrrolidone, and 1,3-dimethyl-2.
-Imidazolidinone, caprolactam, N-methylcaprolactam, hexamethylphosphoramide, tetramethylurea, sulfolane, N, N'-dimethylacetamide, N, N'-ethylenedipyrrolidone and the like. Of these, NMP and 1,3-dimethyl-2-imidazolidinone are preferable.

The phase-separating agent in the present invention is a compound which has a function of dissolving PPS in a polar organic solvent by itself or in the presence of a small amount of water or the like and dissolving it in the polar organic solvent. Is. The phase separating agent itself is
It is a compound that is not a solvent for PPS. For example,
Water, monohydric and polyhydric alcohols such as methanol, ethanol and ethylene glycol, paraffin hydrocarbons, lithium acetate, sodium acetate, lithium propionate, sodium propionate, lithium 2-methylpropionate, rubidium butyrate, lithium
Valeate, sodium valeate, cesium hexanoate, lithium heptanoate, lithium 2
-Methyl octanoate, potassium dodecanoate,
Rubidium 4-ethyl tetradecanoate, sodium octanoate, lithium cyclohexane carboxylate, lithium benzoate, sodium benzoate, potassium benzoate and other carboxylic acid alkali metal salts, lithium chloride, potassium fluoride, calcium chloride and other alkali metals or alkalis There are earth metal halides. These are used alone or as a mixture.

The ratio of PPS, polar organic solvent and phase separating agent contained in the PPS mixture is such that the above-mentioned phase separation state can appear, and is suitable for the production of moderately granular PPS which is easy to handle. It is a ratio. For example, 1 kg of polar organic solvent usually has a PPS value of 0.05 to
It is 1 kg. If the PPS concentration is out of this range, the PPS concentration will be too light or too dark, and will be difficult to handle. 0.1-
0.8 kg is preferable, and 0.2 to 0.6 kg is more preferable. The use ratio of the phase separating agent varies depending on the type of the phase separating agent used, but is usually 0.2 to 20 mol per 1 kg of the polar organic solvent. If the value is out of this limit, it is not preferable because a phase separation state is difficult to appear, PPS is difficult to dissolve, and the cost is high.
It is preferably 0.4 to 15 mol. The PPS, the polar organic solvent and the phase separating agent in the PPS mixture are essential components, and other substances may coexist as long as the object of the present invention is not impaired.

The PPS mixture preferably used in the present invention includes the methods disclosed in JP-B-45-3368, JP-B-52-12240, JP-B-63-337775, and the like. The PPS mixture manufactured by the method according to the method can be illustrated.
When these PPS mixtures do not contain PPS, the polar organic solvent and the phase separating agent in a ratio that allows the above-mentioned phase separation state to appear, the insufficient components are added, and then the method for producing granular PPS according to the present invention is performed. You can apply. Usually, the purpose is achieved by supplementing the polar organic solvent or the phase separation agent. Among these methods, Japanese Examined Patent Publication No. 63-33775
The method disclosed in the publication is particularly preferable.

A method for producing a PPS mixture according to the method disclosed in JP-B-63-33775 and the like will be exemplified below. In this method, an alkali metal sulfide and a dihalo aromatic compound are reacted in a polar organic solvent to obtain PPS, at least in two steps as follows. (1) About 0.5 to 1 mol of charged alkali metal sulfide
In the presence of 10 moles of water at a temperature of about 180-235 ° C,
A step of reacting until the conversion of the dihalo-aromatic compound reaches about 50 mol% or more, (2) coexisting with about 2.5 to 10 mol of water per mol of the charged alkali metal sulfide;
A step of setting the temperature at ˜290 ° C. and continuing the reaction.

The alkali metal sulfides include lithium sulfide, sodium sulfide, potassium sulfide, rubidium sulfide,
Cesium sulfide and mixtures thereof can be exemplified. These alkali metal sulfides can be used as hydrates or aqueous mixtures or in anhydrous form. In order to react with the alkali metal polysulfide which may be contained in a small amount in these alkali metal sulfides, a small amount of alkali metal hydroxide can be added to convert them into alkali metal sulfides. Incidentally, as a precursor of the alkali metal sulfide, lithium disulfide, sodium disulfide, potassium disulfide, rubidium disulfide, cesium disulfide and a mixture thereof and an alkali metal hydroxide in an equimolar amount may be used at the same time. it can. Among these alkali metal sulfides and alkali metal polysulfides,
Sodium sulfide and sodium disulfide are inexpensive and industrially preferable.

Examples of the dihalo aromatic compound include o- and m
-, P-dihalobenzene, 2,5-dihalotoluene,
1,4-dihalonaphthalene, 1-methoxy-2,5-dihalobenzene, 4,4′-dihalobiphenyl, 3,5-
Dihalobenzoic acid, 4,4'-dihalodiphenyl ether, 4,4'-dihalodiphenyl sulfone, 4,4'-
Examples thereof include dihalodiphenyl sulfoxide and 4,4'-dihalodiphenyl ketone. Here, the halogen atom refers to fluorine, chlorine, bromine and iodine atoms, which may be different when a plurality of halogen atoms are contained in the same molecule. These compounds may be used alone or in combination of two or more. Above all, those containing p-dihalobenzene represented by p-dichlorobenzene as a main component are preferable. The amount of the dihalo aromatic compound used is 0.90 to 1.10 per mol of the charged alkali metal sulfide.
The molar amount is preferably 0.95 to 1.05 mol.

As the polar organic solvent, the above polar organic solvent can be used. The amount of polar organic solvent used is about 0.2 to 2 kg per mol of the charged alkali metal sulfide. When the amount of the polar organic solvent used is in this range, the PPS mixture can be obtained.

For the purpose of forming a terminal of PPS or controlling the molecular weight, a monohalo compound can be added before the initiation of the polymerization reaction, during the progress of the polymerization reaction, or at an appropriate time after the completion of the polymerization reaction. Examples of the monohalo compound include monohalo-substituted saturated saturated and unsaturated hydrocarbons such as monohalopropane, monohalobutane, monohaloheptane, monohalohexane, aryl halide and chloroprene, and monohalo substituted saturated unsaturated hydrocarbons such as monohalocyclohexane and monohalodecalin. In addition to cyclic hydrocarbons, monohalo-substituted aromatic hydrocarbons such as monohalobenzene and monohalonaphthalene, and substituted products thereof having a functional group in addition to a halogen atom. Here, the halogen atom refers to fluorine, chlorine, bromine and iodine atoms. These are used within a range that does not impair the object of the present invention.

Further, for the purpose of introducing a crosslinked or branched structure into PPS, or for forming the end of PPS,
It is also possible to add a polyhalo compound of trihalo or more before the initiation of the polymerization reaction, during the progress of the polymerization reaction, or at an appropriate time after the completion of the polymerization reaction. Examples of polyhalo compounds are 1,2,3-trihalobenzene, 1,2,4-trihalobenzene, 1,3,5-trihalobenzene, 2,
4,6-trihalotoluene, 1,2,3,4-tetrahalobenzene, hexahalobenzene, 1,3,5-trihalo 2,4,6-trimethylbenzene, 2,2 ', 4
4'-tetrahalobiphenyl, 2,2 ', 6,6' tetrahalo 3,3 ', 5,5'-tetramethylbiphenyl, 1,2,3,4-tetrahalonaphthalene, 1,2,
4-trihalo-6-methylnaphthalene and the like and mixtures thereof. Here, the halogen atom refers to fluorine, chlorine, bromine and iodine atoms. When a plurality of halogen atoms are contained in the same molecule, they may be different. These are used within a range that does not impair the object of the present invention.

(Phase separation state, solidification temperature of PPS rich phase)
In the method of the present invention, at least a part of the polar organic solvent and / or the phase separating agent is evaporated from the PPS mixture in the phase separated state. By this operation, the temperature of the PPS mixture is rapidly cooled below the temperature at which the PPS concentrated phase solidifies, the PPS concentrated phase rapidly solidifies, and granular PPS having crush resistance is obtained.

The phase-separated state referred to in the present invention is a state in which PPS is dissolved in a polar organic solvent, and a solution phase having a low PPS concentration and a solution phase having a high PPS coexist. The concentration of PPS in the PPS rich phase and the dilute phase depends on the polar organic solvent, the phase separating agent and the type of PPS used. PP consisting of PPS, NMP and water
In the example of the S mixture, the PPS concentration in the PPS rich phase is usually around 50% by weight, and the PPS concentration in the dilute phase is usually 5% by weight or less.

The temperature at which the PPS rich phase solidifies in the present invention means that the above-mentioned PPS rich phase droplets become solid as the temperature of the PPS mixture decreases, and finally the rich phase droplets are combined. First, it is a temperature at which dispersion is not possible, and does not necessarily mean a temperature at which PPS in the PPS rich phase is crystallized. If crystallization of PPS occurs in the PPS rich phase, use a pressure resistant sample container and use DSC (Differential Scanning Calorimeter).
If measured, the solidification temperature of the PPS concentrated phase can be easily known. For example, in the case of a PPS mixture consisting of linear poly (p-phenylene sulfide), NMP and water:
After heating to about 260 ° C. to cause a phase separation state to appear, DSC measurement is performed while lowering the temperature, and an exothermic peak is observed at about 235 ° C. This corresponds to the solidification temperature of the PPS rich phase. The solidification temperature of the PPS concentrated phase depends on various conditions such as the polar organic solvent used, the phase separating agent, and the type of PPS.

(Evaporation of Polar Organic Solvent and / or Phase Separating Agent) In the method of the present invention, at least a part of the polar organic solvent and / or the phase separating agent is evaporated from the PPS mixture in the phase separated state. The temperature of the PPS mixture is cooled below the solidification temperature of the PPS rich phase. The more rapid the cooling rate and the larger the temperature drop width, the more granular PPS with excellent crush resistance can be obtained. The temperature lowering range of the PPS mixture due to evaporation of the polar organic solvent and / or the phase separating agent varies depending on the polar organic solvent used, the difference in thermal properties of the phase separating agent, and the like. Therefore, in the method of the present invention, evaporating at least a part of the polar organic solvent and / or the phase separating agent means that the polar organic solvent is in an amount corresponding to the temperature drop width required to cause the solidification of the PPS rich phase. And / or should be construed to the extent of evaporating the phase separation agent.
As an evaporation method, a method (flash method) in which a PPS mixture in a phase-separated state (usually in a high temperature / high pressure state) is jetted into a low pressure space is generally used. By flushing the PPS mixture in the phase separated state, at least a part of the polar organic solvent and / or the phase separation agent is evaporated, and the temperature of the remaining PPS mixture is cooled below the solidification temperature of the PPS rich phase. The PPS rich phase solidifies and PP
A slurry containing S particles is obtained.

(Recovery of PPS Particles) In order to recover PPS particles, a usual method, a method disclosed in JP-B-63-33775 or the like may be used. That is, after cooling the slurry, PPS particles were recovered using a sieve having an appropriate pore size, and washing with an organic solvent, washing with water, and washing with an acidic aqueous solution or an acidic organic solvent were appropriately performed. Then, it may be dried.

The flushed PPS mixture in the phase-separated state is immediately introduced into a sieve or the like without passing through the slurry state to separate the PPS particles from the organic solvent, and then washed and dried as described above to further crush the particles. It is preferable because PPS particles having resistance can be obtained. The following speculations do not limit the present invention in any way, but by placing the slurry produced by flashing at high temperature as it is, crystallization of the obtained PPS particles proceeds, and the PPS particles are easily crushed. Conceivable.

[0026]

Industrial Applicability According to the method of the present invention, granular PPS having an appropriate particle size distribution and crush resistance can be obtained. In this PPS, the fine PPS particles do not cause clogging or omission of the filter during filtration or dusting during drying, so that the post-treatment process after PPS polymerization is facilitated.
Further, even when handling the dry powder, the molding process is facilitated because the powder does not become fine and does not stand up.

[0027]

EXAMPLES Examples will be shown below, but the present invention is not limited thereto. (Average particle diameter) The average particle diameter of the granular PPS was measured as follows. First, Japanese Industrial Standard JIS K0069
The particle size distribution of the sample is measured in accordance with the test method of 1 and is shown in an integrated percentage graph. Then, the point at which the cumulative percentage became 50% was read from the graph and used as the average particle size.

(Powdering rate) The pulverizing rate defined below was used as a measure of the crush resistance of PPS particles. JIS beforehand
50 g of granular PPS sample recovered using a -100 mesh sieve was transferred to a JIS-100 mesh stainless sieve and shaken with a shaker for 10 minutes, and the weight of the sample that passed through the sieve, that is, crushed by shaking. The PPS was weighed and the pulverization rate was calculated according to the following formula. The shaking frequency with the shaker is about 300 times / minute. PPS with low powdering rate
The higher the crush resistance.

Powdering rate (%) = {weight of sample passed through sieve (g) / 50 (g)} × 100

(Example of Synthesis of PPS Mixture) 3800 g (22.43 mol, purity 46.06% by weight) of sodium sulfide and 6700 g of NMP were charged into a pressure-resistant autoclave and gradually heated to 200 ° C. with stirring. As a result, distillate 249 containing 1561 g of water and 916 g of NMP
6 g was distilled off from the autoclave. As a result of this operation,
The analysis revealed that 21.90 mol of sodium sulfide, about 27.2 mol of water, and 5784 g of NMP remained in the autoclave. To the mixture in the autoclave, p
-3413 g (23.21 mol) of dichlorobenzene, 102 g of water, and 4071 g of NMP were added and reacted at 220 ° C for 4 hours and 30 minutes. Subsequently, 986 g of water was added to the mixture in the autoclave, the temperature was raised to 255 ° C. and the reaction was continued for 5 hours.
An S mixture (A) was obtained.

From about half of the PPS mixture (A) above,
The granular PPS polymer was recovered using a JIS-100 mesh stainless steel sieve. The recovered polymer was washed 3 times with acetone, 3 times with water, then 1 at 105 ° C. in air.
After drying for 6 hours, granular PPS (B) having a melt viscosity of 160 poise (310 ° C., shear rate of 1200 / sec) was obtained. The average particle size was 320 μm, and the pulverization rate was 6.82%.

(Example 1) The above-mentioned granular PPS (B) 100 was placed in a pressure-resistant autoclave having an outlet at the bottom.
g, NMP (500 g) and water (72 g) were charged, the space was replaced with nitrogen, and the mixture was kept at 255 ° C. for 1 hour to allow a phase separation state to appear. The PPS mixture in the phase-separated state was extracted from the extraction port at the bottom and placed in another stainless steel container,
It spewed out under atmospheric pressure. The evaporated NMP and water were condensed and collected by a condenser. Next, the granular PPS was immediately separated and recovered from the slurry containing the granular PPS using a JIS-100 mesh sieve. The recovered PPS was washed 3 times with acetone and 3 times with water, then dried in air at 105 ° C. for 16 hours. The PPS recovery rate was 93.5%, the average particle size was 460 μm, and the pulverization rate was 1.8%.

(Embodiment 2) The granular PPS (B) 100 was placed in a pressure resistant autoclave having an outlet at the bottom.
g, NMP (500 g) and water (72 g) were charged, the space was replaced with nitrogen, and the mixture was kept at 255 ° C. for 1 hour to allow a phase separation state to appear. The PPS mixture in the phase-separated state was taken out from the bottom outlet and jetted into another autoclave under atmospheric pressure. The evaporated NMP and water were condensed and collected by a condenser. Then, the autoclave containing the slurry containing granular PPS was heated to 200 ° C. and then cooled to room temperature with stirring. Granular PPS was separated and collected using a JIS-100 mesh sieve, washed with acetone three times and water three times, and then in air at 105 ° C. for 16 times.
Dried for hours. The PPS recovery rate was 84.6%, the average particle size was 360 μm, and the pulverization rate was 4.8%.

(Example 3) The above-mentioned granular PPS (B) 100 was placed in a pressure-resistant autoclave having an outlet at the bottom.
g, NMP (500 g) and water (72 g) were charged, the space was replaced with nitrogen, and the mixture was kept at 255 ° C. for 1 hour to allow a phase separation state to appear. The PPS mixture in the phase-separated state was extracted from the extraction port at the bottom and directly flushed on a JIS-100 mesh screen. By this operation, the PPS concentrated phase was solidified, and at the same time, the granular PPS was separated from the liquid component. The recovered PPS was washed 3 times with acetone and 3 times with water, then dried in air at 105 ° C. for 16 hours. PP
The recovery rate of S was 95.2%, the average particle size was 620 μm, and the pulverization rate was 0.93%.

(Comparative Example 1) The granular PPS (B) 100 was placed in a pressure resistant autoclave having an outlet at the bottom.
g, NMP (500 g) and water (72 g) were charged, the space was replaced with nitrogen, and the mixture was kept at 255 ° C. for 1 hour to allow a phase separation state to appear. Then, the mixture was allowed to cool to room temperature while continuing stirring. Granular PPS using a JIS-100 mesh screen
Was recovered. The recovered PPS was washed 3 times with acetone and 3 times with water, then dried in air at 105 ° C. for 16 hours. P
PS recovery rate is 79.3%, average particle size is 320 μm,
The pulverization rate was 7.1%.

(Example 4) A PPS mixture (A) 750 was placed in a pressure-resistant autoclave having an outlet on the bottom.
After charging g and purging the space with nitrogen, the temperature was maintained at 255 ° C. for 1 hour to allow a phase separation state to appear. The PPS mixture in the phase-separated state was extracted from the bottom outlet and spouted into another stainless steel container under atmospheric pressure. The evaporated NMP and water were condensed and collected by a condenser. Next, the granular PPS was immediately separated and recovered from the slurry containing the granular PPS using a JIS-100 mesh sieve. The recovered PPS was washed 3 times with acetone and 3 times with water,
Then, it was dried in air at 105 ° C. for 16 hours. Recovery PP
The average particle size of S was 430 μm, and the pulverization rate was 1.6%.

(Example 5) A PPS mixture (A) 750 was placed in a pressure-resistant autoclave having an outlet on the bottom.
After charging g and purging the space with nitrogen, the temperature was maintained at 255 ° C. for 1 hour to allow a phase separation state to appear. The PPS mixture in the phase-separated state was extracted from the extraction port at the bottom and directly flushed on a JIS-100 mesh screen.
By this operation, the PPS concentrated phase was solidified, and at the same time, the granular PPS was separated from the liquid component. The recovered PPS was washed 3 times with acetone and 3 times with water, then in air at 105 ° C.
And dried for 16 hours. The average particle size of the recovered PPS is 510
μm, and the pulverization rate was 1.02%.

Comparative Example 2 A PPS mixture (A) 750 was placed in a pressure-resistant autoclave having a bottom with an outlet.
After charging g and purging the space with nitrogen, the temperature was maintained at 255 ° C. for 1 hour to allow a phase separation state to appear. Then, the mixture was allowed to cool to room temperature while continuing stirring. Granular PPS was recovered using a JIS-100 mesh screen. The recovered PPS is washed 3 times with acetone, 3 times with water, then 105 in air.
It was dried at ℃ for 16 hours. The average particle size of the recovered PPS is 31.
The particle size was 0 μm and the pulverization rate was 6.9%.

Claims (4)

[Claims] 1. A mixture containing polyphenylene sulfide, a polar organic solvent and a phase separating agent, wherein the polyphenylene sulfide is in a phase separated state in which a dilute solution phase and a concentrated solution phase coexist, and the polar organic solvent and / or A method for producing granular polyphenylene sulfide having crush resistance, which comprises cooling at least a part of the phase separating agent to lower the temperature of the mixture to a temperature at which the dense phase solidifies. 2. A mixture of polyphenylene sulfide, a polar organic solvent and a phase separating agent is a compound of sulfur and at least one metal selected from alkali metals and alkaline earth metals in a polar organic solvent, and a dihaloaromatic compound. The method for producing granular polyphenylene sulfide having crush resistance according to claim 1, which is a mixture formed by dehalogenation / sulfurization of and. 3. At least a part of the polar organic solvent and / or the phase-separating agent is evaporated by jetting the mixture in a phase-separated state into an atmosphere of lower pressure, and the temperature of the mixture is raised. The method for producing granular polyphenylene sulfide having crush resistance according to claim 1, wherein the concentrated phase is cooled to a temperature at which it solidifies or lower. 4. The phase-separated mixture is jetted under an atmosphere of lower pressure to solidify the concentrated phase,
The method for producing granular polyphenylene sulfide having crush resistance according to claim 3, wherein the solidified concentrated phase is immediately separated and recovered.