JPH1045911A - Purification method of polyarylene sulfide - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a purification method for producing a PAS having a low content of metal ions and excellent in physical properties such as a color after melting with a relatively simple apparatus. SOLUTION: An inorganic acid and / or an organic acid is added to a slurry containing an organic polar solvent and a polyarylene sulfide or the like after the reaction obtained by reacting a dihalo aromatic compound with a sulfidizing agent in an organic polar solvent. In addition, in the method of purifying the polyarylene sulfide polymer by performing treatments such as filtration, washing with water, and drying after stirring and washing, the amount of the inorganic acid and / or the organic acid is controlled so that the pH of the slurry exceeds 7, And wash at least once with 10
A method for purifying a polyarylene sulfide polymer, which is carried out at 0 ° C. or higher.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for purifying polyarylene sulfide (hereinafter abbreviated as PAS) represented by polyphenylene sulfide (hereinafter abbreviated as PPS).

More specifically, the present invention controls the pH of the slurry to a specific range by adding an inorganic acid and / or an organic acid to the slurry after the reaction, and performs water washing at least once at a specific temperature or higher. The present invention provides a purification method for producing PAS having a low content of metal ions and having excellent physical properties such as color after melting by a relatively simple apparatus.

[0003]

2. Description of the Related Art PAS represented by PPS has heat resistance,
The molded product has been widely used in recent years for electronic and electronic parts, automobile parts, and the like by utilizing properties excellent in molding workability and the like. However, higher purity is demanded mainly for electric and electronic parts and the like, and in particular, reduction of the content of metal ions mainly including Na ions is desired.

As a means for reducing metal ions, a method using no acid includes, for example, (1) JP-A-60-2
No. 10631, JP-A-62-185718,
JP-A-59-217728, JP-A-59-219
No. 331, etc., however, these methods are complicated and rarely give satisfactory results.

As an excellent means for reducing metal ions, a method using an acid has been conventionally known. For example, (2) Japanese Patent Application Laid-Open No. 62-223232 discloses that a polar solvent after completion of the reaction is used. There is disclosed a method for purifying PPS, which comprises adding an inorganic acid or an organic acid to a slurry of PPS, washing the mixture with stirring at a pH of 6 or less, filtering, washing with water, and drying.

[0006]

The method (2)
Can reduce alkali metal ions as compared with the case where no acid is added. However, gas is generated when the obtained polymer is melted, coloring is intense, and pH is set to 6 or less. There were problems such as the need for special equipment.

The present invention solves the above-mentioned drawbacks of the conventional production method and provides a purification method for producing a PAS having a low content of metal ions and excellent physical properties such as a color at the time of melting by a relatively simple apparatus. The purpose is to do.

[0008]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to achieve the above object, and as a result, a PAS having a low metal ion content and excellent physical properties such as color when melted has been obtained by a relatively simple apparatus. For the production, it has been found that it is important to control the slurry after the reaction to a specific range of pH, and to carry out water washing at least once at 100 ° C. or higher. And a sulfidizing agent obtained by the reaction, after the reaction is completed, an inorganic acid and / or an organic acid is added to a slurry containing an organic polar solvent and polyarylene sulfide, and the pH is controlled so as to exceed 7, And wash at least once with water
By conducting the purification at a temperature of not lower than 00 ° C., it was found that a PAS having a low metal ion content and excellent physical properties such as a color at the time of melting can be produced by a relatively simple apparatus, and completed the present invention.

That is, the present invention relates to a method of reacting a dihalo-aromatic compound with a sulfidizing agent in an organic polar solvent, and adding an inorganic acid and / or a polyarylene sulfide to a slurry containing the organic polar solvent and polyarylene sulfide after completion of the reaction. In a method of purifying a polyarylene sulfide polymer by performing treatments such as filtration, water washing, and drying after adding an organic acid and stirring and washing, the amount of the inorganic acid and / or the organic acid is adjusted so that the pH of the slurry exceeds 7. Provided is a method for purifying a polyarylene sulfide polymer, wherein the method comprises controlling and washing with water at least once at 100 ° C. or higher.

Conventionally, when an acid is added at the time of purification to lower the pH to 6 or less, there are problems in terms of physical properties of the polymer such as generation of gas when molten and severe coloration,
In addition, although a special device corresponding to an acid is required, the method of the present invention does not require a special device such as an acid device because the pH exceeds 7, and a combination of washing with water at a high temperature allows metal ions to be obtained. It is possible to obtain a polymer having a low content and excellent stability during melting. That is, the present invention is a completely different method from the conventional method.

[0011]

DETAILED DESCRIPTION OF THE INVENTION In the present invention, the terms "sulfidizing agent", "dihalo-aromatic compound" and "solvent" are mixtures of the compounds or substances mentioned within the respective defined ranges. Case. For example, the present invention includes, as one specific example, a case where the “dihalo-aromatic compound” is composed of a plurality of types of compounds and the produced PAS is a copolymer.

(Production of polymer) The method for producing PAS in the present invention is based on a dehalogenation / sulfurization reaction of a dihaloaromatic compound with a sulfidizing agent, and various known methods can be used. is there.

(Sulfidizing agent) Examples of the sulfidizing agent used in the present invention include alkali metal sulfides, alkali metal hydrosulfides, and mixtures thereof.

Examples of the alkali metal sulfide include lithium sulfide, sodium sulfide, potassium sulfide, rubidium sulfide, and cesium sulfide. These may be used alone or as a mixture of two or more. May be used. Further, the alkali metal sulfide is an anhydride,
Either a hydrate or an aqueous solution may be used.

Among the above alkali metal sulfides, sodium sulfide and potassium sulfide are preferable, and sodium sulfide is particularly preferable.

These alkali metal sulfides can be obtained, for example, by reacting an alkali metal hydrosulfide with an alkali metal base, or hydrogen sulfide with an alkali metal base, but those prepared outside the reaction system may be used. .

Examples of the alkali metal hydrosulfide include lithium hydrosulfide, sodium hydrosulfide, potassium hydrosulfide, rubidium hydrosulfide, and cesium hydrosulfide. These may be used alone or in combination of two types. The above may be used as a mixture. Further, the alkali metal hydrosulfide,
Any of an anhydride, a hydrate, and an aqueous solution may be used.

Among the above alkali metal hydrosulfides, sodium bisulfide and potassium bisulfide are preferred, and sodium bisulfide is particularly preferred.

These alkali metal hydrosulfides can be obtained by reacting hydrogen sulfide with an alkali metal base, but those prepared outside the reaction system may be used.

Examples of the alkali metal base include alkali metal hydroxide. Examples of the alkali metal hydroxide include lithium hydroxide, sodium hydroxide, potassium hydroxide, rubidium hydroxide, cesium hydroxide, and the like. These may be used alone, respectively.
Mixtures of more than one species may be used.

Among the above alkali metal hydroxide compounds, lithium hydroxide, sodium hydroxide and potassium hydroxide are preferred, and sodium hydroxide is particularly preferred.

In any of the above cases, a small excess of alkali metal base may be added in order to remove impurities present in trace amounts in the alkali metal sulfide and alkali metal hydrosulfide.

The above-mentioned sulfidizing agent may be an anhydride, but is preferably a hydrate from the viewpoint of easy availability and controllability of the reaction. When an anhydride is used, it is used by adding water.

(Dihalo Aromatic Compound) The dihalo aromatic compound corresponding to the monomer to form the skeleton of the aromatic sulfide polymer has an aromatic nucleus and two halo substituents on the nucleus. Any one can be used as long as it can be polymerized through a dehalogenation / sulfidation reaction with a sulfidizing agent such as an alkali metal sulfide. Therefore, the aromatic nucleus may have various substituents which do not inhibit the dehalogenation / sulfidation reaction, in addition to the case where the aromatic nucleus is composed of only the aromatic hydrocarbon.

Specifically, examples of the dihalo aromatic compound used in the present invention include compounds represented by the following formulas (A) to (D).

[0026]

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Here, each substituent has the following meaning. X: Cl, Br, I or F. In particular, at least one halogen selected from the group consisting of Cl and Br.

Y: -R, -OR, -COOR, -COO
Na, (the R, H, an alkyl group, a cycloalkyl group, those selected from the group consisting of aryl and aralkyl groups) -CN and -NO ₂ those selected from the group consisting of. Here, the alkyl group or the alkyl group portion has 1 to 18 carbon atoms.
Degree, the aryl group or the aryl group moiety has 6 to 1 carbon atoms.
About 8 are normal.

[0029]

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(R ′ and R ″ are selected from the group consisting of H, an alkyl group, a cycloalkyl group, an aryl group and an aralkyl group). Here, the alkyl group or the alkyl group part and the aryl group or the aryl group part are defined as described above.

In the formula (A), m and n are respectively m =
2, an integer of 0 ≦ n ≦ 4. In the formula (B), a and b are each an integer of a = 2 and 0 ≦ b ≦ 6. In the formula (C), c, d,
e and f are respectively 0 ≦ c ≦ 2, 0 ≦ d ≦ 2, c + d
= 2, 0 ≦ e, f ≦ 2.

In the formula (D), g, h, i and j are respectively 0 ≦ g ≦ 2, 0 ≦ h ≦ 2, g + h = 2, 0 ≦ i, j ≦
An integer of 2.

The following are examples of the dihalogen-substituted aromatic compound represented by the above general formula.

P-dihalobenzene, m-dihalobenzene, o-dihalobenzene, 2,5-dihalotoluene,
1,4-dihalonaphthalene, 1-methoxy-2,5-dihalobenzene, 4,4′-dihalobiphenyl, 3,5-
Dihalobenzoic acid, 2,4-dihalobenzoic acid, 2,5-dihalonitrobenzene, 2,4-dihalonitrobenzene,
2,4-dihaloanisole, p, p'-dihalodiphenylether, 4,4'-dihalobenzophenone, 4,
4'-dihalodiphenyl sulfone, 4,4'-dihalodiphenyl sulfoxide, 4,4'-dihalodiphenyl sulfide, etc., among which p-dihalobenzene, m
-Dihalobenzene, 4,4'-dihalobenzophenone and 4,4'-dihalodiphenylsulfone are preferred,
Among them, p-dichlorobenzene, m-dichlorobenzene, 4,4′-dichlorobenzophenone and 4,4 ′
-Dichlorodiphenyl sulfone is particularly preferably used.

As described above, a copolymer containing two or more different reaction units can be obtained by an appropriate combination of dihaloaromatic compounds. If p-dichlorobenzene and 4,4'-dichlorobenzophenone or 4,4'-dichlorophenylsulfone are used in combination,

[0036]

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Unit and

[0038]

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Unit or

[0040]

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A copolymer containing units can be obtained.

However, it is possible to copolymerize,
70 mol% of p-dihalobenzene in dihalo aromatic compound
Or more, preferably 90 mol% or more, and more preferably 95 mol% or more.
PPS excellent in various physical properties when polymerized using more than mol%
Is preferred.

The amount of the dihaloaromatic compound used in the present invention is preferably in the range of 0.8 to 1.3 mol per mol of the sulfur source in the sulfidizing agent used, and particularly preferably 0.9 to 1.3 mol.
The range of 1.10 mol is preferable for obtaining a polymer having excellent physical properties.

The PAS according to the present invention is a polymer of the above-mentioned dihalo-aromatic compound. However, in order to form the terminal of the produced polymer or to control the polymerization reaction or the molecular weight, the mono-halo compound (not necessarily the aromatic compound) is used. ) Or a polyhalo compound of trihalo or more (not necessarily an aromatic compound) to form a branched or crosslinked polymer.

Specific examples where the monohalo or polyhalo compound is an aromatic compound will be obvious to those skilled in the art as the monohalo or polyhalo derivative of the above specific examples. Specifically, for example, if a small amount of trichlorobenzene is used in combination with dihalobenzene, a phenylene sulfide polymer having a branch can be obtained.

The amount of the monohalo or polyhalo compound used cannot be specified unconditionally because it varies depending on the purpose and reaction conditions, but is preferably 0.1 mol or less, more preferably 0.1 mol or less, per 1 mol of the dihalo aromatic compound. 05
Mol or less.

(Solvent and Water) As the organic polar solvent used in the polymerization reaction of the present invention, known organic polar solvents can be used, but an organic polar solvent having no active hydrogen, that is, an aprotic organic polar solvent is preferable.

The organic polar solvent must not unduly inhibit the polymerization reaction of the present invention. Further, this solvent contains at least a dihalo aromatic compound as a raw material and S ^2-
Should be capable of dissolving the sulfidizing agent giving the concentration required for the reaction.

Therefore, the solvent is usually a polar solvent having a nitrogen atom, an oxygen atom and / or a sulfur atom. Further, it is desirable that this solvent does not participate in the dehalogenation / sulfurization reaction similar to the starting dihalo aromatic compound. Thus, for example, it is desirable not to be a haloaromatic hydrocarbon. Further, in the production method of the present invention,
Optimally, the solvent used has a boiling point higher than that of water.

Specific examples of such a solvent include:
(1) Amides, for example hexamethylphosphoric triamide (HMPA), N-methyl-2-pyrrolidone
-Methylpyrrolidone (NMP), N-cyclohexylpyrrolidone (NCP), N-methylcaprolactam, tetramethylurea (TMU), dimethylformamide (DM
F), dimethylacetamide (DMA), and others,
(2) etherified polyethylene glycol such as polyethylene glycol dialkyl ether (polymerization degree: 20
Up to about 00, the alkyl group is about C ₁ -C ₂₀ ), etc.
(3) Sulfoxides, such as tetramethylene sulfoxide, dimethyl sulfoxide (DMSO) and others. Among the above various solvents, N-methylcaprolactam and NMP are particularly preferable because of their high chemical stability.

The amount of the solvent used depends on the type of the solvent used, but in order to maintain the viscosity of the reaction system capable of performing a uniform polymerization reaction and to maintain a certain level of productivity, it is used in the polymerization. The range is preferably from 1.0 to 6 mol per mol of the sulfur source in the sulfidizing agent. Further, in consideration of productivity, the range of 1.2 to 5.0 moles per 1 mole of the sulfur source in the sulfidizing agent used in the polymerization is preferable, and the more preferable amount of the solvent used is in the sulfidizing agent used in the polymerization. 1.5 to 4 moles per mole of the sulfur source.

The water for adjusting the water content in the polymerization system or the water content of the sulfidizing agent may be any water that does not hinder the reaction. Water excluding anions and cations is preferred. Further, the water used in the water washing step is preferably water having a metal ion content of 5 ppm or less. Therefore, it is preferable to use, for example, distilled water, ion-exchanged water and the like.

In general, the amount of water that should be present during the polymerization reaction of the present invention is preferably as small as possible in order to avoid concurrent hydrolysis and the like. However, when the sulfidizing agent used is a hydrate or the like, even if the sulfidizing agent is heated and dehydrated in an organic polar solvent, 1 mol or more per 1 mol of the sulfidizing agent remains in the system. Therefore, it is difficult to reduce the water content in the system, and the water content in the system is 1-2 mol, preferably 1-mol, per mol of the sulfidizing agent.
1.5 mol.

(Polymerization) The polymerization according to the present invention may be carried out after the dehydration operation, if necessary, or while performing the dehydration operation.
The heating is preferably performed at a temperature of 00 to 300 ° C, preferably 210 to 280 ° C, for 0.1 to 40 hours, preferably 0.5 to 20 hours, more preferably 1 to 10 hours. Within this range, the reaction proceeds smoothly.

That is, if the reaction temperature is lower than 200 ° C., the reaction rate may be slow and the reaction may be uneven. On the other hand, if the reaction temperature is higher than 300 ° C., side reactions such as decomposition of the produced polymer or solvent are likely to occur. .

The reaction time cannot be specified unconditionally because it depends on the type and amount of the raw materials used, or the reaction temperature. However, if the reaction time is less than 0.1 hour, the amount of unreacted components increases or the produced polymer has a low molecular weight. And more than 40 hours is not preferable because productivity is poor.

In the polymerization reaction of the present invention, a polymerization vessel whose liquid contact part is made of titanium, chromium, zirconium or the like is used, and it is usually preferable to carry out the reaction in an atmosphere of an inert gas such as nitrogen, helium or argon. Nitrogen is preferred from the viewpoints of economy, ease of handling, and the like.

There is no particular limitation on the reaction pressure.
Since it depends on the type and amount of the used raw materials and the solvent, the reaction temperature, and the like, the conditions are appropriately selected and adopted.

The reaction solution preparation and copolymer formation reaction may be a one-step reaction performed at a constant temperature, a multi-step reaction in which the temperature is increased stepwise, or the temperature is continuously changed. It doesn't matter if the reaction is a form of reaction.

(Purification) The most important feature of the present invention resides in this purification step. For example, the slurry obtained after the completion of the reaction containing the organic polar solvent and polyarylene sulfide obtained as described above is subjected to purification. This slurry is usually
Not only organic polar solvents, polyarylene sulfide,
It contains other chemical components. In the case of using a dihalo aromatic compound and an alkali metal sulfide as raw materials, the other chemical components in the slurry include:
A reaction by-product that can be dissociated into metal ions is typical.

After completion of the reaction, the obtained organic polar solvent and PA
S-containing slurry as it is, or as a reaction solvent (or a solvent having equivalent low molecular polymer solubility)
After adding and stirring, the mixture is stirred as it is at the same temperature or cooled, or after adding a reaction solvent (or a solvent having a low molecular polymer solubility equivalent to that) and stirring.
An inorganic acid and / or an organic acid is added so that the pH of the slurry is more than 7, preferably more than 7 and not more than 9, and the slurry is homogenized.

The pH of the slurry is directly measured without diluting with water, and the value measured at 50 ° C. is used in the present invention. The pH of the slurry may be measured by various known methods, a method using a pH meter, a method using a pH test paper, a method using an indicator, or the like. In particular, pH
A method using a meter is most preferable from the viewpoint of operability and the like.

The acid used in the present invention is not particularly limited.
Examples of the inorganic acid include hydrochloric acid, sulfuric acid, sulfurous acid, phosphoric acid, nitric acid, nitric acid and the like, and among them, hydrochloric acid, sulfuric acid and phosphoric acid are preferable. Examples of the organic acid include saturated fatty acids such as formic acid, acetic acid and propionic acid, unsaturated fatty acids such as acrylic acid and crotonic acid, aromatic fatty acids such as benzoic acid and phthalic acid, oxalic acid, maleic acid and adipic acid. Examples thereof include sulfonic acids such as dicarboxylic acid and p-toluenesulfonic acid. Among them, formic acid, acetic acid and oxalic acid are preferred.

In the present invention, it is essential to add an inorganic acid and / or an organic acid, but the pH must not be reduced to 7 or less. If the pH of the slurry is reduced to 7 or less, it is not preferable from the viewpoint of physical properties of the polymer, such as remarkable coloring when the obtained polymer is melted, and if the pH is lowered, it is necessary to use expensive acid-compatible equipment.

When an acid is added and the pH after the addition is higher than 7, a PAS having a low content of metal ions and excellent physical properties such as a color at the time of melting can be manufactured even in a device which does not support an acid.

After homogenizing the slurry by adding an acid, the slurry is filtered. The filtration temperature is not particularly limited,
The temperature is preferably 50 ° C. or higher and the boiling point of the solvent used for the reaction at normal pressure or lower, more preferably 100 ° C. or higher and 190 ° C. or lower.

The filtration includes, for example, an operation of solid-liquid separation using a filter, a centrifugal separator or the like. After the filtration, the obtained solid content may be subjected to a water washing treatment as described below as it is. However, after filtering the slurry, the mother liquor attached to the solid content was further washed with a heated solvent,
It is more preferable to remove the adhesion of the mother liquor.

The removal amount of the mother liquor is 50% or more, preferably 70% or more, more preferably 90% or more, of the mother liquor adhered before washing. The greater the removal amount, the better the physical properties such as the color at the time of melting.

The obtained solid content may be washed with water as it is, but for example, acetone, methyl ethyl ketone,
After washing once or twice or more with a solvent such as alcohols, washing may be performed with water. The solvent-washed or non-washed solid is washed once or twice with water. In this washing step, washing is performed at a high temperature at least once.

The washing temperature at this high temperature is usually 100 ° C.
Or more, preferably 160 ° C. or more, more preferably 190 ° C.
° C or higher. Performing water washing at such a high temperature effectively reduces the metal ion content, which is one of the objects of the present invention.

After washing with water, drying is performed to obtain the desired PAS. Drying is performed by heating the isolated PAS to a temperature at which a solvent such as water substantially evaporates. Drying may be performed under vacuum, or may be performed in air or under an inert gas atmosphere such as nitrogen.

The obtained polymer can be used as it is for various molding materials and the like, but it can be thickened by heat treatment in air or oxygen-enriched air or under reduced pressure. After performing a thickening operation,
It may be used for various molding materials.

The heat treatment temperature varies depending on the treatment time and the atmosphere in which the treatment is performed, so that it cannot be unconditionally specified.
If the heat treatment temperature is lower than 180 ° C., the rate of thickening is extremely slow, and the productivity is poor, which is not preferable. The heat treatment may be performed in a molten state at a temperature higher than the melting point of the polymer using an extruder or the like. However, from the possibility of polymer deterioration or workability, melting point plus 1
It is preferable to carry out at a temperature of not higher than 00 ° C.

The polymer obtained according to the present invention is a conventional P
As with AS, a molded product excellent in heat resistance, molding workability, dimensional stability, etc. can be directly obtained by various melt processing methods such as injection molding, extrusion molding, compression molding, and blow molding. However, in order to further improve the performance such as strength, heat resistance and dimensional stability, it is also possible to use in combination with various fillers as long as the object of the present invention is not impaired.

Examples of the filler include a fibrous filler and an inorganic filler. Examples of the fibrous filler include fibers such as glass fiber, carbon fiber, silane glass fiber, ceramic fiber, aramid fiber, metal fiber, potassium titanate, silicon carbide, calcium sulfate, calcium silicate, and natural fibers such as wollastonite. Etc. can be used. In addition, as the inorganic filler, barium sulfate, calcium sulfate, clay, viroferrite, bentonite, sericite, zeolite, mica, mica, talc, atalpargite, ferrite, calcium silicate, calcium carbonate, magnesium carbonate, glass beads, etc. Can be used.

Further, a small amount of an additive such as a releasing agent, a coloring agent, a heat stabilizer, an ultraviolet stabilizer, a foaming agent, a rust inhibitor, a flame retardant may be used as an additive during the molding process without departing from the object of the present invention. , A lubricant and a coupling agent.

Further, similarly, the following synthetic resins and elastomers can be mixed and used. As these synthetic resins, polyester, polyamide, polyimide, polyetherimide, polycarbonate, polyphenylene ether, polysulfone, polyethersulfone, polyetheretherketone, polyetherketone, polyarylene, polyethylene, polypropylene, polytetrafluoroethylene, Polydifluoroethylene, polystyrene, ABS
Resins, epoxy resins, silicone resins, phenolic resins, urethane resins, liquid crystal polymers and the like can be mentioned, and elastomers include polyolefin rubber, fluorine rubber, silicone rubber and the like.

The polymer of the present invention and the composition thereof are excellent in heat resistance and dimensional stability like PAS obtained by a conventional method, and therefore, for example, electric / electronic parts such as connectors, printed boards, molded articles, etc. Injection molding, compression molding, or composite molding of automotive parts such as lamp reflectors and various electrical components, interior materials of various buildings, aircraft and automobiles, and precision parts such as OA equipment parts, camera parts and watch parts・ Extrusion molding of sheets, pipes, etc.
Excellent molding materials or fibers with excellent heat resistance, molding processability, dimensional stability, etc. in various molding processing fields such as pultrusion molding.
Used as a film.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

[0080]

EXAMPLES Hereinafter, the raw materials used in the examples and the like will be described in advance.

1. Sulfidizing agent (alkali metal sulfide) Crystalline sodium sulfide (pentahydrate) (hereinafter, Na ₂ S · 5H ₂₎
O) is a product of Sankyo Chemical Co., Ltd.

2. The solvent N-methylpyrrolidone (hereinafter abbreviated as NMP) is
Uses Mitsubishi Chemical Corporation products.

3. Dihalo aromatic compound p-dichlorobenzene (hereinafter abbreviated as p-DCB)
Uses products of Sumitomo Chemical Co., Ltd.

4. Water Distilled tap water and ion-exchanged (metal ion content 5 ppm or less) is used.

5. Sulfuric acid 98% sulfuric acid is a special grade manufactured by Kishida Chemical Co., Ltd.

6. Hydrochloric acid Sulfuric acid uses a special grade of 35% manufactured by Kishida Chemical Co., Ltd. still,
The above percentages are all percentages by weight.

<Evaluation of Physical Properties> The melt viscosity (η) of the obtained polymer was measured using a Koka flow tester (316 ° C., shear rate 100 / sec, nozzle diameter 0.5 m).
m, length 1.0 mm). The sodium ion content of the obtained polymer is an aqueous solution of the residue obtained by calcining the polymer,
It measured with the atomic absorption altimeter. The pH was measured using a pH meter Model PH82 manufactured by Yokogawa Electric Corporation and a composite electrode supplemented with KCl. The color is melt-kneaded at 330 ° C. for 5 minutes to form a pellet, and the pellet is pressed at 320 ° C. to form a sheet with a thickness of 2 mm.
The color of the sheet was measured. In addition, it evaluated by L value.

Reference Example 1 Preparation of slurry: 2185.6 g of Na ₂ S.5H ₂ O in a 10-liter autoclave with stirring blades connected to a temperature sensor, a rectification tower, a dropping tank, a dropping pump, and a distillate receiving tank.
(13.0 mol) and 4461 g (45.0 mol) of NMP were charged, and the temperature was raised to 200 ° C. under a nitrogen atmosphere to distill off a water-NMP mixture. The composition in the distillate is 258 g NMP, 903 g water, 85 m ionic sulfur
mol.

The system was closed, the system was heated to 220 ° C., and 1911.0 g (13.0 mol) of p-DCB was added to N
A solution dissolved in 1300 g of MP was dropped at a constant rate over 2 hours. After completion of the dropwise addition, the temperature was maintained at 220 ° C. for 3 hours.
Thereafter, the temperature was raised to 250 ° C. over 1 hour, and the temperature was maintained for 1 hour to complete the reaction. After the completion of the reaction, the resultant was cooled to room temperature.

[0092] 500 g of the obtained slurry was poured into 5 liters of water, stirred at 50 ° C for 1 hour, and filtered. The cake was again stirred with 5 liters of water at 50 ° C. for 1 hour, washed, and filtered. This operation was repeated four times, followed by filtration and drying overnight (120 ° C.) with a hot air drier to obtain 78 g of a white powdery PPS polymer.

The obtained polymer had a melt viscosity of 460 poise and a sodium ion ion content of 830 pp.
m. The L value of the sheet was 57.2.

Example 1 0.4 g of sulfuric acid was added to 250 g of the polymerization slurry obtained in Reference Example 1 to adjust the pH of the slurry to 7.8. The pH of the slurry before sulfuric acid was added
Was 12.3. The pH-adjusted slurry was heated to 150 ° C. while stirring under a nitrogen atmosphere, kept at that temperature for 10 minutes, and then filtered at that temperature using a special heat-retaining suction filtration device. 330 mesh stainless steel (SUS304) wire mesh (diameter 125 mm)
It was used. Before and after filtration, no change such as corrosion was observed in the filter medium.

The cake was prepared by heating NMP2 to 150 ° C.
Washed twice with 00 g. The cake was further added to 2000 g of water, stirred at 50 ° C. for 1 hour, washed, and filtered. This operation was repeated four times. However, the third washing of the four washings was performed at 120 ° C.

After washing with water and filtering, a hot air drier is used overnight (120
C) and dried to obtain 36 g of a white powdery PPS polymer. The melt viscosity of the obtained polymer was 550 poise, and the content of sodium ion ions was 180 ppm. The L value of the sheet was 63.1.

Example 2 The procedure of Example 1 was repeated, except that the third washing was performed at 170 ° C. of the four washings. The resulting polymer has a melt viscosity of 540 poise and a sodium ion ion content of 130 ppm.
Met. The L value of the sheet was 64.0.

Example 3 The same procedure as in Example 1 was carried out except that the third washing was performed at 200 ° C. among the four washings. The resulting polymer has a melt viscosity of 530 poise and a sodium ion ion content of 110 ppm.
Met. The L value of the sheet was 64.1.

Example 4 0.8 g of hydrochloric acid instead of sulfuric acid
The procedure was the same as in Example 3 except that the pH of the slurry after the addition of hydrochloric acid was lower than before the addition but exceeded 7. The resulting polymer has a melt viscosity of 540 poise and a sodium ion ion content of 120 p.
pm. The L value of the sheet was 64.2.

Example 5 The temperature at which the slurry was filtered was set to 8
The procedure was performed in the same manner as in Example 3 except that the temperature was changed to 0 ° C. The resulting polymer had a melt viscosity of 540 poise and a sodium ion ion content of 130 ppm. The L value of the sheet was 64.8.

[Comparative Example 1] The same operation as in Example 1 was performed without adding sulfuric acid. The resulting polymer has a melt viscosity of 590 poise and a sodium ion ion content of 500 p.
pm. The L value of the sheet was 63.3.

Comparative Example 2 The same procedure as in Example 1 was carried out except that the amount of sulfuric acid was changed to 1.6 g. The pH of the slurry after the addition of sulfuric acid was 3.2. The resulting polymer had a melt viscosity of 500 poise and a sodium ion ion content of 150 ppm. The L value of the sheet was 54.9. It was significantly colored compared to the polymer of Example 1. Further, the filter medium used for filtration at 150 ° C. was significantly corroded.

[Comparative Example 3] The same procedure as in Example 1 was performed, except that the water washing performed four times was all performed at 50 ° C. The resulting polymer had a melt viscosity of 570 poise and a sodium ion ion content of 300 ppm. The L value of the sheet was 63.0.

[0102]

According to the purification method of the present invention, an inorganic acid and / or an organic acid is added to the slurry after the reaction, and the pH of the slurry is adjusted.
Is filtered in a specific range and washed with water at a specific temperature or higher, so that a particularly remarkable effect of obtaining a PAS having a small content of metal ions and excellent physical properties such as color after melting can be obtained. Moreover, even in the purification method, there is no need for an apparatus that takes into account the properties of the acid to be added, and the above-mentioned excellent effect of producing an excellent PAS can be achieved simultaneously with a relatively simple apparatus.

Claims (6)

[Claims] An inorganic acid and / or an organic acid are added to a slurry obtained by reacting a dihalo-aromatic compound with a sulfidizing agent in an organic polar solvent and containing the organic polar solvent and polyarylene sulfide after completion of the reaction. In a method of purifying a polyarylene sulfide polymer by adding an acid and washing with stirring, followed by filtration, washing with water, drying and the like, the amount of the inorganic acid and / or organic acid is controlled so that the pH of the slurry exceeds 7. And wash at least once with water
A method for purifying a polyarylene sulfide polymer, which is performed at a temperature of 00 ° C. or higher. 2. The purification method according to claim 1, wherein the slurry controlled by adding an inorganic acid and / or an organic acid is a slurry having a pH of more than 7 and 9 or less. 3. The purification method according to claim 1, wherein the washing is performed at least once at 160 ° C. or higher. 4. The water used for washing has a metal ion content of 5.
The purification method according to claim 1, wherein the water is at most ppm. 5. The polyarylene sulfide according to claim 1, wherein the polyarylene sulfide is polyphenylene sulfide.
5. The purification method according to any one of 4. 6. The method according to claim 1, wherein the organic polar solvent is N-methyl-2-pyrrolidone.