JP6402971B2 - Sulfiding agent and method for producing polyarylene sulfide resin - Google Patents

Description

  The present invention relates to a method for producing a sulfidizing agent and a method for producing a polyarylene sulfide resin using the same. More specifically, a method for separating, purifying, and producing a sulfidizing agent from waste water discharged in the production process of the polyarylene sulfide resin, and a polyarylene sulfide resin in which the obtained sulfidizing agent is reused as part of the raw material. It relates to a manufacturing method.

  Polyarylene sulfide resin (PAS resin), typified by polyphenylene sulfide resin (PPS resin), has excellent heat resistance and chemical resistance, and is widely used for electrical and electronic parts, automotive parts, water heater parts, fibers, films, etc. Has been. In particular, in applications such as packing for lithium ion batteries and gasket members, in recent years, high molecular weight polyarylene sulfide resins have been widely used because of their excellent toughness and moldability.

  The polyarylene sulfide resin is prepared by converting a polyhaloaromatic compound into an alkali metal sulfide and / or an alkali metal hydrosulfide in an aprotic polar solvent such as N-methyl-2-pyrrolidone (hereinafter sometimes abbreviated as NMP). It can be obtained by a method of polymerizing with a product (hereinafter sometimes referred to as a sulfidizing agent), but with the target polyarylene sulfide resin, the remaining alkali metal hydrosulfide or alkali metal sulfide without solvent or polymerization reaction. A crude reaction product containing a by-product such as a sulfidizing agent such as an alkali metal halide represented by sodium chloride, other alkali metal-containing inorganic salts, oligomers generated by side reactions and derivatives thereof is obtained. The crude reaction product after the polymerization reaction is taken out into an appropriate container, and the solvent in the crude reaction product is separated by solvent removal using an appropriate solid-liquid separation device such as a solvent drying device, a filter, or a centrifuge. It is recovered (this operation is called desolvation).

  Furthermore, since the reaction product obtained after the desolvation treatment contains an alkali metal halide and other alkali metal-containing inorganic salt and by-products together with the target polyarylene sulfide resin, washing with water and filtration are repeated, These are removed. In general, there are a water washing method performed at less than 100 ° C. and a hot water washing performed at a high temperature and high pressure of 100 ° C. or higher. The polyarylene sulfide obtained after washing with water or hot water is separated with a filter, a centrifugal filter or the like, then dried, and subjected to a heat treatment as necessary to obtain a product.

  On the other hand, wastewater obtained after washing with water or hot water has been treated as industrial waste and has not been effectively utilized. However, since the wastewater has a high COD load, it has been required to reduce COD substances in order to reduce the environmental load.

  As a treatment method for reducing COD substances in wastewater, for example, an acid flocculant is added to wastewater to adjust pH, so that COD substances are insolubilized, and insolubilized COD substances are separated. Etc. are known (see Patent Document 1). However, in this method, the waste water of the purification process is introduced, the mixing function is provided, and the aggregation reaction tank equipped with the pH indicating controller and capable of pH adjustment and aggregation treatment is introduced from the aggregation reaction tank. Since the separation is performed using a continuous centrifugal separator that separates the insolubilized COD material, the water content of the separated COD material is high and cannot be reused as a raw material for producing the polyarylene sulfide resin. Moreover, since the COD substance separated by the acidic flocculant is precipitated in a large floc form, it must be treated as industrial waste, which is not preferable.

JP 2003-275773 A

  Therefore, when waste water discharged by water washing or hot water washing after the polymerization reaction was examined in detail, the sulfidizing agent that remained unreacted was converted to sulfur atoms and remained at about 3 to 5 mol% of the charged amount. It is clear that the unreacted sulfidizing agent is one of the factors that increase the COD value of wastewater, and further causes the loss of sulfur atoms (decrease in raw material basic unit). became.

  Therefore, the problem to be solved by the present invention is to recover the unreacted sulfidizing agent contained in the waste water discharged by water washing or hot water washing after the polymerization reaction of the polyarylene sulfide resin, and to reduce the COD value of the waste water. It is to provide a method. Furthermore, a method for producing a polyarylene sulfide resin, in which the recovered unreacted sulfidizing agent is reused as a polymerization raw material for the polyarylene sulfide resin, and a method for suppressing loss of sulfur atoms (decrease in raw material basic unit) are provided. It is to provide.

  As a result of various investigations, the inventors of the present application have found that wastewater discharged by water washing or hot water washing after the polymerization reaction includes alkali metal halides and side reactions in addition to the sulfidizing agent remaining without polymerization. Since by-products such as oligomers and their derivatives are contained, the unreacted sulfidizing agent is once gasified, separated and recovered to remove and recover the unreacted sulfidizing agent from the wastewater. In this way, the present inventors have found that the COD of wastewater can be reduced and reused as a raw material for producing a polyarylene sulfide resin, and the above problems have been solved.

That is, the present invention provides [1] contacting at least a polyarylene sulfide resin, an alkali metal halide and a sulfidizing agent-containing mixture (a) with water, then separating and removing the polyarylene sulfide resin, (1) obtaining an aqueous solution (b) containing an alkali metal halide and a sulfidizing agent,
A step (2) of adding an acid to the aqueous solution (b) containing at least an alkali metal halide and a sulfidizing agent to produce hydrogen sulfide;
Recovering the produced hydrogen sulfide (3), and
A step (4) of reacting the obtained hydrogen sulfide with an alkali metal hydroxide;
The present invention relates to a method for producing a sulfidizing agent, characterized by comprising:

The present invention also provides [2] a mixture (a) containing at least a polyarylene sulfide resin, an alkali metal halide and a sulfidizing agent.
A crude product containing at least a polyarylene sulfide resin, an alkali metal halide, the aprotic polar solvent and a sulfidizing agent obtained after reacting a polyhaloaromatic compound with a sulfidizing agent in an aprotic polar solvent. The production method according to the above [1], which is a reaction mixture or a reaction mixture obtained by solid-liquid separation of the aprotic polar solvent from the crude reaction mixture.
The present invention also provides [3] the sulfidizing agent used when the polyhaloaromatic compound and the sulfidizing agent are reacted in an aprotic polar solvent at least in the presence of the aprotic polar solvent. The production method according to [2], which is obtained through a dehydration step of dehydrating a sulfidizing agent.

  Furthermore, the present invention provides [4] step (4) of reacting the obtained hydrogen sulfide with an alkali metal hydroxide, adding hydrogen sulfide to the unreacted alkali metal hydroxide, The present invention relates to the production method according to [1], which includes a step (5) of reacting hydrogen with an unreacted alkali metal hydroxide.

  Furthermore, the present invention includes [5] a step of recovering hydrogen sulfide generated in the dehydration step according to the above [3] and then reacting with an alkali metal hydroxide to obtain a sulfidizing agent. The present invention relates to a method for producing a sulfiding agent.

  Furthermore, the present invention provides [6] a step of reacting with an alkali metal hydroxide to obtain an alkali metal hydrosulfide and / or alkali metal sulfide, and then hydrogen sulfide is added to the unreacted alkali metal hydroxide. In addition, the present invention relates to the method for producing a sulfidizing agent according to the above [5], comprising a step of reacting the hydrogen sulfide with an unreacted alkali metal hydroxide.

  The present invention further provides [7] a polyarylene sulfide resin obtained by reacting a sulfidizing agent obtained by dehydrating a hydrous sulfidizing agent in the presence of an organic amide solvent with a polyhaloaromatic compound in the presence of an organic amide solvent. In the method for producing a polyarylene sulfide resin, the sulfidizing agent obtained by the production method according to any one of the above [1] to [4] and / or the water-containing sulfidizing agent or sulfidizing agent. The present invention relates to a method for producing a polyarylene sulfide resin, comprising a step of adding a sulfidizing agent obtained by the production method of [5] or [6].

  According to the present invention, it is possible to provide a method for recovering the unreacted sulfidizing agent contained in waste water discharged by water washing or hot water washing after the polymerization reaction of the polyarylene sulfide resin and reducing the COD value of the waste water. it can. Furthermore, a method for producing a polyarylene sulfide resin, in which the recovered unreacted sulfidizing agent is reused as a polymerization raw material for the polyarylene sulfide resin, and a method for suppressing loss of sulfur atoms (decrease in raw material basic unit) are provided. Can be provided.

The method for producing a sulfidizing agent of the present invention comprises at least contacting a mixture (a) containing polyarylene sulfide resin, alkali metal halide and sulfidizing agent with water, and then separating and removing the polyarylene sulfide resin. Step (1) to obtain an aqueous solution (b) containing at least an alkali metal halide and a sulfidizing agent,
A step (2) of adding an acid to the aqueous solution (b) containing at least an alkali metal halide and a sulfidizing agent to produce hydrogen sulfide;
Recovering the produced hydrogen sulfide (3), and
A step (4) of reacting the obtained hydrogen sulfide with an alkali metal hydroxide.

  In step (1), at least a mixture (a) containing a polyarylene sulfide resin, an alkali metal halide and a sulfidizing agent is contacted with water, and an aqueous solution (b) containing the alkali metal halide and the sulfidizing agent is contacted. This is a step of separating the polyarylene sulfide resin and then removing the polyarylene sulfide resin to obtain an aqueous solution (b) containing at least an alkali metal halide and a sulfidizing agent.

  The mixture (a) used in the step (1) is not particularly limited as long as it is a mixture containing at least a polyarylene sulfide resin, an alkali metal halide and a sulfidizing agent. It is preferable to use a reaction mixture obtained at least in the method for producing a polyarylene sulfide resin used in 1), which contains at least a polyarylene sulfide resin, an alkali metal halide and a sulfidizing agent.

  A method for obtaining an aqueous solution (b) containing at least an alkali metal halide and a sulfidizing agent by contacting the mixture (a) with water to remove the polyarylene sulfide resin from the mixture (a). Although not particularly limited as long as the effects of the invention are not impaired, a method of solid-liquid separation by filtering the polyarylene sulfide resin after contact with water (hereinafter sometimes referred to as “washing”) is described. Can be mentioned.

  Examples of the method for solid-liquid separation by bringing the mixture (a) into contact with water and then separating the polyarylene sulfide resin by filtration include, for example, aprotic from the crude reaction mixture obtained in the PAS production step described later. A method in which water is added to the reaction slurry obtained by solid-liquid separation of the polar solvent and stirred, followed by filtration using a filtration device, and a filtration residue containing moisture obtained by the filtration described above (hereinafter referred to as “water-containing cake”). For example, a method of adding water again to form a slurry and filtering, or a method of adding water again and filtering while the water-containing cake is held in a filter can be used.

  In the water washing, the amount of water added to the mixture (a) is preferably in the range of 2 to 10 times the theoretical yield of the finally obtained polyarylene sulfide, preferably from the viewpoint of washing efficiency, The amount of water is preferably divided into 2 to 10 times, preferably 2 to 4 times, and subjected to water washing. The water washing is preferably performed in a nitrogen or air atmosphere at a water temperature in the range of 20 ° C. to 300 ° C., and more preferably in the range of 50 ° C. to 100 ° C. Furthermore, it is most preferable to carry out in the range of 70 ° C to 90 ° C. The water washing can be repeated once or a plurality of times. When water washing is repeated a plurality of times, the atmosphere and temperature conditions may be the same or different.

  In the polyarylene sulfide resin separated by filtration, trace amounts of alkali metal halides and sulfidizing agents may remain without being sufficiently washed. Therefore, they contact with water in the range of 100 ° C. to 280 ° C. The polyarylene sulfide resin can be separated and removed by filtration or the like, and the resulting filtrate can be added to the aqueous solution (b). From the viewpoint of reducing the COD load and suppressing loss of sulfur atoms (decrease in raw material basic unit).

  The temperature of the hot water washing is, for example, preferably in the range of 100 to 280 ° C., and more preferably in the range of 120 to 275 ° C., so that the extraction efficiency of the alkali metal halide and sulfiding agent remaining in the resin is improved. To preferred. More specifically, the extraction treatment may be carried out with hot water at 140 to 260 ° C. under the pressure of the gas phase in the reactor under pressure, more preferably 0.2 to 4.6 MPa (gauge pressure). preferable.

  As a specific method for performing such hot water washing, there is a method of washing the polyarylene sulfide resin filtered off after the water washing with stirring in water under a predetermined pressure condition and temperature condition in a pressure vessel. The amount of water at the time of hot water washing is preferably 1.5 times to 10 times the mass of polyarylene sulfide from the viewpoint of good extraction efficiency of the alkali metal halide or sulfiding agent. You may divide water into 2 times or more and perform hot water washing. For example, when hot water washing is repeated twice, filtration is performed between the first hot water washing and the second hot water washing, and the alkali metal halide, sulfidizing agent and polyarylene sulfide resin extracted by the first hot water washing are used. Is preferably filtered off. Moreover, after performing hot water washing once, it may filter and may carry out an above described water washing. This operation can further promote the separation and removal of the alkali metal halide and sulfidizing agent from the polyarylene sulfide resin. Moreover, although the conditions of the 1st hot water washing process and the 2nd hot water washing process can be selected arbitrarily from said conditions, the temperature of the 1st hot water washing process is the temperature which exists in the range of 120 to 200 degreeC, for example. After setting and removing the first highly alkaline filtrate by filtration, the temperature of the second hot water washing step is set to a temperature higher than the temperature of the first hot water washing step, for example, in the range of 150 ° C. to 275 ° C. It is preferable to implement it from the viewpoint of chemical resistance of the apparatus used in the hot water washing.

  In step (1), the pH can be adjusted by adding an acid or a base to the aqueous solution (b), and in particular, the pH after hot water washing is in the range of 11.0 to less than 13.0. It is preferable to control. Examples of the acid used at that time include hydrochloric acid, sulfuric acid, carbonic acid, acetic acid, and oxalic acid. Among these, carbonic acid, acetic acid, and oxalic acid are preferable. Further, carbon dioxide gas may be introduced and contacted at normal pressure or under pressure. On the other hand, examples of the base include alkali metal hydroxides such as lithium hydroxide, sodium hydroxide, and potassium hydroxide, or sodium carbonate, ammonium carbonate, sodium phosphate, and the like. Among these, sodium hydroxide is preferable.

  In the step (1), it is possible to use a washing tank having a stirrer and a centrifuge for solid-liquid separation, but the container has a stirring blade and a filter for filtration is disposed at the bottom. It can also be carried out in a container having a mixed function. Moreover, even in hot water washing exceeding 100 ° C., it is possible to use a centrifuge in order to filter at a water washing tank having a stirrer that performs hot water washing and then 20 to 100 ° C. It is also possible to carry out in a closed type container having a blade and having a filter for filtration at the bottom or a mixing function capable of being sealed. In the present invention, water washing or hot water washing may be carried out continuously or in a batch manner.

Step (2) is a step of generating hydrogen sulfide by adding an acid to the aqueous solution (b) containing at least an alkali metal halide and a sulfidizing agent.
Examples of the acid used in this case include hydrochloric acid, sulfuric acid, carbonic acid, and acetic acid. Among these, hydrochloric acid is preferable. The pH range of the aqueous solution (b) is not particularly limited as long as it is a range in which hydrogen sulfide is generated by adding an acid. It is preferable to carry out in the range of 0.5, more preferably in the range of 3.5 to 4.5. The addition of the acid is preferably performed in the range of 0 to 60 ° C., more preferably in the range of 10 to 40 ° C., and performed in the pressure range of 0 to 1.0 Pa (gauge pressure). preferable.

  The step (3) is a step of subsequently recovering the generated hydrogen sulfide because the hydrogen sulfide generated in the step (2) is vaporized as a gas. Furthermore, the step (4) is a step of reacting the obtained hydrogen sulfide with an alkali metal hydroxide. Step (3) and step (4) can be performed simultaneously or separately.

  When performing the step (3) and the step (4) at the same time, for example, the volatilized hydrogen sulfide is discharged out of the system and absorbed and recovered in an aqueous solution containing an alkali metal hydroxide. The method of making it react with an alkali metal hydroxide and producing | generating a sulfidizing agent is mentioned. In this case, as the alkali metal hydroxide to be used, the same one as used in the above PAS polymerization step can be used. The amount of alkali metal hydroxide used depends on the temperature and pressure at which hydrogen sulfide is absorbed, so it cannot be specified in general, but it must be sufficient to absorb and react with the entire amount of hydrogen sulfide that is volatilized. Is desirable. Generally, when hydrogen sulfide is absorbed and reacted at room temperature and normal pressure, it is preferably 1 mol or more with respect to 1 mol of sulfur atom of hydrogen sulfide to be volatilized, and if it is in the range of 1 to 2 mol. More preferred. Although the concentration of the alkali metal hydroxide in the aqueous solution also varies depending on the temperature and pressure at the time of absorbing and reacting with hydrogen sulfide, it cannot be defined unconditionally, but is preferably in the range of 5 to 49 wt%, More preferably, it is in the range of 45 wt%. Moreover, since the temperature at the time of absorbing and reacting hydrogen sulfide in an aqueous solution containing an alkali metal hydroxide varies depending on the pressure, it cannot be generally specified, but a range of 0 to 200 ° C. is preferable, and 10 to 150 ° C. The range of is more preferable. Moreover, since the pressure at the time of absorbing and reacting hydrogen sulfide with an aqueous solution containing an alkali metal hydroxide varies depending on the temperature, it cannot be generally specified, but a range of 0 to 1.0 Pa (gauge pressure) is preferable. A range of 0 to 0.5 Pa (gauge pressure) is more preferable.

  On the other hand, when the step (3) and the step (4) are performed separately, for example, a volatilized hydrogen sulfide is discharged out of the system, and a solvent known to absorb hydrogen sulfide, such as an organic amide, for example. After performing the process of absorbing and recovering in a solvent, an alkali metal hydroxide is added to the solvent containing the recovered hydrogen sulfide, and the hydrogen sulfide and the alkali metal hydroxide are reacted to produce an alkali metal hydrosulfide. The method of performing the process to make is mentioned. In this case, an organic amide solvent is mentioned as a solvent known to absorb hydrogen sulfide. Further, organic amide solvents include formamide, acetamide, N-methylformamide, N, N-dimethylacetamide, tetramethylurea, N-methyl-2-pyrrolidone, 2-pyrrolidone, N-methyl-ε-caprolactam, ε- Examples include caprolactam, hexamethylphosphoramide, N-dimethylpropyleneurea, amides such as 1,3-dimethyl-2-imidazolidinone, and urea. Among these, N-methyl-2-pyrrolidone, 2- An amide having an aliphatic cyclic structure of pyrrolidone, N-methyl-ε-caprolactam, ε-caprolactam, hexamethylphosphoramide, N-dimethylpropyleneurea, 1,3-dimethyl-2-imidazolidinone acid is preferable, N-methyl-2-pyrrolidone is more preferred.

  Although the amount of solvent known to absorb hydrogen sulfide varies depending on the temperature and pressure when absorbing hydrogen sulfide, it cannot be defined in general, but it can fully absorb all of the volatilized hydrogen sulfide. It is desirable to be more than the amount. In general, when hydrogen sulfide is absorbed at room temperature and normal pressure, it is preferably in the range of 1 to 30 kg with respect to 1 mol of sulfur atom of hydrogen sulfide to be volatilized. Although the temperature and pressure when absorbing hydrogen sulfide in a solvent known to absorb hydrogen sulfide cannot be generally specified, the absorption temperature is preferably in the range of 0 to 200 ° C, and preferably 10 to 150 ° C. The range is more preferable, while the pressure is preferably in the range of 0 to 1.0 Pa (gauge pressure), and more preferably in the range of 0 to 0.5 Pa (gauge pressure). Thereafter, an alkali metal hydroxide is added to the recovered solvent containing hydrogen sulfide to react the hydrogen sulfide with the alkali metal hydroxide to produce an alkali metal hydrosulfide. At that time, the amount of the alkali metal hydroxide added is preferably not less than an amount capable of sufficiently reacting with the total amount of hydrogen sulfide absorbed in the solvent. In general, when hydrogen sulfide is absorbed at room temperature and normal pressure, it is preferably 1 mol or more with respect to 1 mol of sulfur atom of hydrogen sulfide absorbed in the solvent, and may be in the range of 1 to 2 mol. More preferable. Although the concentration of the alkali metal hydroxide in the aqueous alkali solution added to the solvent also varies depending on the temperature and pressure when absorbing hydrogen sulfide, it cannot be generally specified, but is preferably in the range of 5 to 49 wt%, A range of 10 to 45 wt% is more preferable. In addition, the temperature at which the hydrogen sulfide absorbed in the solvent reacts with the alkali metal hydroxide varies depending on the pressure, and thus cannot be generally specified, but the temperature is preferably in the range of 0 to 200 ° C. A range of ˜150 ° C. is more preferable. Further, although the pressure cannot be generally defined, a range of 0 to 1.0 Pa (gauge pressure) is preferable, and a range of 0 to 0.5 Pa (gauge pressure) is more preferable.

  Step (3) may be either a continuous type or a batch type. Since the absorption rate of hydrogen sulfide to alkali metal hydroxide aqueous solution or organic amide solvent is fast, it can be a general one such as a packed tower with a circulation pump, and a liquid-filled type or bubbling type can also be used sufficiently. is there. Moreover, when performing process (3) and process (4) simultaneously, process (4) can be performed in the same apparatus as process (3), and process (3) and process (4) are performed separately. In this case, even if the step (4) is performed in the same apparatus as the step (3), the hydrogen sulfide recovered in the step (3) is transferred to another apparatus, for example, a reaction vessel with a stirring blade, a vessel, a drum, or the like. Later, an alkali metal hydroxide may be added and allowed to react.

  As described above, in step (3) and step (4), since the alkali metal hydroxide is used in an amount that can sufficiently absorb and react with the entire amount of hydrogen sulfide recovered, excess alkali metal hydroxide is not reacted. It remains in the system as it is. Therefore, after the step (4), there is a step (5) of adding hydrogen sulfide to the unreacted alkali metal hydroxide to react the unreacted alkali metal hydroxide with the hydrogen sulfide. Is preferred. The amount of hydrogen sulfide to be added is preferably in the range of 0.5 to 1 mol with respect to 1 mol of the alkali metal hydroxide remaining unreacted. By reacting with hydrogen sulfide in this range, 0.5 to 1 mole of alkali metal hydrosulfide and / or alkali metal sulfide is produced per mole of remaining alkali metal hydroxide.

  In addition, the ratio of the alkali metal hydrosulfide and alkali metal sulfide produced | generated through process (4) or process (5) is the quantity of the alkali metal hydroxide made to react with hydrogen sulfide, reaction time, temperature, pressure. It is not possible to define it unconditionally because it varies depending on the etc., and any of alkali metal hydrosulfides and alkali metal sulfides can be used again as a sulfidizing agent which is a polymerization raw material for polyarylene sulfide resins described later. Since it can be used, the alkali metal hydrosulfide and the alkali metal sulfide may be in any ratio within the range of 0/100 to 100/0 on a mass basis.

  As the mixture (a) containing at least a polyarylene sulfide resin, an alkali metal halide and a sulfidizing agent used in the present invention, those obtained by the following method for producing a polyarylene sulfide resin can be used. In addition, the alkali metal hydrosulfide and / or alkali metal sulfide obtained through the above steps (1) to (4) or steps (1) to (5) is used as a sulfidizing agent, and the following polyarylenes: In the method for producing a sulfide resin, it can be used as at least a part of a polymerization raw material.

PAS Polymerization Step That is, the method for producing a polyarylene sulfide resin used in the present invention comprises mixing an aprotic polar solvent, a polyhaloaromatic compound, and a sulfidizing agent, and in the aprotic polar solvent, A compound and a sulfidizing agent are polymerized to obtain a crude reaction mixture containing at least a polyarylene sulfide resin, a sulfidizing agent remaining without polymerization, an alkali metal halide, and an aprotic polar solvent. PAS polymerization step, a reaction mixture obtained by solid-liquid separation of an aprotic polar solvent from the crude reaction mixture, comprising at least a polyarylene sulfide resin, a sulfidizing agent remaining without being polymerized, and an alkali metal halide The method of passing through a PAS / solvent solid-liquid separation step can be mentioned.

  Here, in the present invention, the polyhaloaromatic compound is, for example, a halogenated aromatic compound having two or more halogen atoms directly bonded to an aromatic ring, specifically, p-dichlorobenzene, o -Dichlorobenzene, m-dichlorobenzene, trichlorobenzene, tetrachlorobenzene, dibromobenzene, diiodobenzene, tribromobenzene, dibromonaphthalene, triiodobenzene, dichlorodiphenylbenzene, dibromodiphenylbenzene, dichloro And dihaloaromatic compounds such as benzophenone, dibromobenzophenone, dichlorodiphenyl ether, dibromodiphenyl ether, dichlorodiphenyl sulfide, dibromodiphenyl sulfide, dichlorobiphenyl, dibromobiphenyl, and mixtures thereof. These compounds may be block copolymerized. Of these, dihalogenated benzenes are preferred, and those containing p-dichlorobenzene of 80 mol% or more are particularly preferred. Further, for the purpose of increasing the viscosity of the polyarylene sulfide resin by using a branched structure, a polyhaloaromatic compound having 3 or more halogen substituents in one molecule may be used as a branching agent as desired. Examples of such polyhaloaromatic compounds include 1,2,4-trichlorobenzene, 1,3,5-trichlorobenzene, 1,4,6-trichloronaphthalene, and the like. Furthermore, polyhaloaromatic compounds having a functional group having active hydrogen such as amino group, thiol group, hydroxyl group can be mentioned. Specifically, 2,6-dichloroaniline, 2,5-dichloroaniline 2,4-dichloroaniline, 2,3-dichloroaniline and other dihaloanilines; 2,3,4-trichloroaniline, 2,3,5-trichloroaniline, 2,4,6-trichloroaniline, 3, Trihaloanilines such as 4,5-trichloroaniline; dihaloaminodiphenyl ethers such as 2,2′-diamino-4,4′-dichlorodiphenyl ether and 2,4′-diamino-2 ′, 4-dichlorodiphenyl ether Examples thereof include compounds in which the amino group is replaced by a thiol group or a hydroxyl group in a mixture thereof. In addition, active hydrogen-containing polyhalo compounds in which the hydrogen atom bonded to the carbon atom forming the aromatic ring in these active hydrogen-containing polyhaloaromatic compounds is substituted with another inert group, for example, a hydrocarbon group such as an alkyl group. Aromatic compounds can also be used.

  Among these various active hydrogen-containing polyhaloaromatic compounds, an active hydrogen-containing dihaloaromatic compound is preferable, and dichloroaniline is particularly preferable.

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

  In the present invention, examples of the sulfidizing agent include alkali metal sulfides and / or alkali metal hydrosulfides.

  Examples of the alkali metal sulfide include lithium sulfide, sodium sulfide, rubidium sulfide, cesium sulfide, and mixtures thereof. Such alkali metal sulfides can be used as hydrates, aqueous mixtures or anhydrides. The alkali metal sulfide can also be derived from the reaction between an alkali metal hydrosulfide and an alkali metal hydroxide. Normally, a small amount of alkali metal hydroxide may be added to react with alkali metal hydrosulfide or alkali metal thiosulfate present in a trace amount in the alkali metal sulfide.

  The alkali metal hydrosulfide includes lithium hydrosulfide, sodium hydrosulfide, rubidium hydrosulfide, cesium hydrosulfide, and mixtures thereof. Such alkali metal hydrosulfides can be used as hydrates, aqueous mixtures or anhydrides.

  The alkali metal hydrosulfide is used together with an alkali metal hydroxide. Examples of the alkali metal hydroxide include lithium hydroxide, sodium hydroxide, potassium hydroxide, rubidium hydroxide, and cesium hydroxide. These may be used alone or in combination of two or more. May be used. Among these, lithium hydroxide, sodium hydroxide, and potassium hydroxide are preferable because they are easily available, and sodium hydroxide is particularly preferable.

  As described above, the alkali metal hydrosulfide and / or alkali metal sulfide obtained through the steps (1) to (4) or the steps (1) to (5) is also used as a sulfidizing agent. It can be reused as a raw material in the polymerization reaction of sulfide resin.

  The method for producing a polyarylene sulfide resin used in the present invention can also use a water-containing sulfidizing agent as a raw material. In that case, through a step of dehydrating the water-containing sulfidizing agent in the presence of at least an aprotic polar solvent, It is preferable to use for the polymerization reaction of polyarylene sulfide resin. In addition, when the amount of the aprotic polar solvent charged is small, for example, when it is less than 1 mole relative to 1 mole of the sulfur atom of the sulfidizing agent, the hydrous sulfidizing agent and the non-sulfating agent are added in the presence of the polyhaloaromatic compound. It is preferable to dehydrate the protic polar solvent.

  In the dehydration step, at least an aprotic polar solvent and a hydrous alkali metal sulfide or a hydrous alkali hydrosulfide and an alkali metal hydroxide as a hydrous sulfiding agent are charged into a reaction vessel provided with a distillation apparatus, and water is used together. The temperature is removed by boiling, specifically, it is heated to 300 ° C. or lower, preferably 80 to 220 ° C., more preferably 100 to 200 ° C., and water is discharged out of the system by distillation. To do. In the dehydration step, dehydration is performed until the amount of water in the system in which the polymerization reaction is performed is 5 mol or less, more preferably in the range of 0.01 to 2.0 mol per mol of the sulfur atom of the sulfidizing agent. It is preferable.

  In the dehydration step, alkali metal sulfide or alkali metal hydrosulfide reacts with water to generate hydrogen sulfide as a gas in a balanced manner. For this reason, after recovering the produced hydrogen sulfide, it is preferable to react with an alkali metal hydroxide to obtain an alkali metal hydrosulfide and / or alkali metal sulfide. Specifically, the produced hydrogen sulfide is discharged out of the reaction system together with water or an azeotrope, and after separation of water or azeotrope and hydrogen sulfide by a distillation apparatus, the same method as in the above step (3) The recovered hydrogen sulfide is further reacted with an alkali metal hydroxide in the same manner as in the step (4) to produce an alkali metal hydrosulfide and / or alkali metal sulfide. It is preferable to do. Further, after the step of reacting the hydrogen sulfide recovered in the dehydration step with an alkali metal hydroxide to produce an alkali metal hydrosulfide and / or alkali metal sulfide, the same method as in step (5) is performed. It is preferable to include a step of adding hydrogen sulfide to the unreacted alkali metal hydroxide to react the unreacted alkali metal hydroxide with the hydrogen sulfide. The alkali metal hydrosulfide and / or alkali metal sulfide obtained in the dehydration step is also preferably used as a part of the raw material in the method for producing a polyarylene sulfide resin as a sulfidizing agent.

  In the present invention, the aprotic polar solvent includes formamide, acetamide, N-methylformamide, N, N-dimethylacetamide, tetramethylurea, N-methyl-2-pyrrolidone, 2-pyrrolidone, N-methyl-ε. Amides such as caprolactam, ε-caprolactam, hexamethylphosphoramide, N-dimethylpropyleneurea, 1,3-dimethyl-2-imidazolidinone, urea and lactams; sulfolanes such as sulfolane and dimethylsulfolane; benzos Nitriles such as nitrile; ketones such as methyl phenyl ketone and mixtures thereof can be mentioned, among which N-methyl-2-pyrrolidone, 2-pyrrolidone, N-methyl-ε-caprolactam, ε-caprolactam, Hexamethylphosphoramide, N-di Chill propylene urea, 1,3-dimethyl-2-amide having an aliphatic cyclic structure imidazolidinone acids are preferred, more preferably N- methyl-2-pyrrolidone.

  In the polymerization reaction of the polyarylene sulfide resin in the PAS polymerization step, the alkali metal sulfide is reacted with the polyhaloaromatic compound as a sulfidizing agent in the presence of these aprotic polar solvents. Alternatively, in the polymerization reaction of the polyarylene sulfide resin, the alkali metal hydrosulfide and alkali metal hydroxide are reacted with the polyhaloaromatic compound as a sulfidizing agent in the presence of these aprotic polar solvents. The polymerization conditions are generally in the range of 200 to 330 ° C., and the pressure should be in such a range as to keep the polymerization solvent and the polymerization monomer polyhaloaromatic compound in a substantially liquid phase. It is selected from the range of 1-20 MPa, preferably from the range of 0.1-2 MPa. The charged amount of the polyhaloaromatic compound is in the range of 0.2 mol to 5.0 mol, preferably in the range of 0.8 to 1.3 mol, more preferably, with respect to 1 mol of the sulfur atom of the sulfidizing agent. Prepare to be in the range of 0.9 to 1.1 moles. The amount of the aprotic polar solvent charged is in the range of 1.0 to 6.0 mol, preferably in the range of 2.5 to 4.5 mol, with respect to 1 mol of the sulfur atom of the sulfidizing agent. adjust. The polymerization reaction is preferably performed in the presence of a small amount of water, and the proportion is preferably adjusted as appropriate in consideration of the polymerization method and the molecular weight and productivity of the polymer obtained. Specifically, the dehydration operation is performed so as to be in the range of 2.0 mol or less, preferably 1.6 mol or less with respect to 1 mol of the sulfur atom of the sulfidizing agent, and further dehydration in the presence of a polyhaloaromatic compound. In the case of performing the operation (for example, the method of “5)” in the following specific embodiment), 0.9 mol or less, preferably 0.05 to 0.3 mol, more preferably 0.01 to 0.02 mol or less. The dehydration operation may be performed so as to be in the range.

As a specific embodiment for polymerizing the sulfidizing agent and the polyhaloaromatic compound in the presence of the aprotic polar solvent described above, for example,
1) A method using a polymerization aid such as an alkali metal carboxylate or lithium halide,
2) A method using a branching agent such as an aromatic polyhalogen compound,
3) A method in which a polymerization reaction is carried out in the presence of a small amount of water and then water is added for further polymerization,
4) A method in which during the reaction between the alkali metal sulfide and the aromatic dihalogen compound, the gas phase portion of the reaction kettle is cooled to condense part of the gas phase in the reaction kettle and reflux to the liquid phase,
5) In the presence of a polyhaloaromatic compound, an alkali metal sulfide, or a hydrous alkali metal hydrosulfide and an alkali metal hydroxide, and an amide, urea or lactam having an aliphatic cyclic structure are reacted while being dehydrated. Obtained through a step of producing a slurry containing a solid alkali metal sulfide, a step of adding a polar organic solvent such as NMP and dehydrating by distilling off water after producing the slurry, followed by a dehydration step. In the resulting slurry, a polyhaloaromatic compound, an alkali metal hydrosulfide, and an alkali metal salt of an amide, urea or lactam hydrolyzate having an aliphatic cyclic structure are mixed with 1 mol of a polar organic solvent such as NMP. In contrast, polyarylene sulfide having a process of performing polymerization by reacting at a water content of 0.02 mol or less in the reaction system as an essential process. The method of manufacturing a resin, and the like.

  Among these, in the case of producing a polyarylene sulfide resin by the polymerization method of 1) to 5), particularly 1) to 4), as a production raw material, for example, an aprotic polar solvent is N-methyl-2-pyrrolidone. When the polyhaloaromatic compound is p-dichlorobenzene, as a side reaction product of the polymerization reaction, the following general formula (1)

（式中、Ｘはアルカリ金属原子または水素原子を表す。）で表されるカルボキシアルキルアミノ基含有化合物が該粗反応混合物に含まれる場合がある。本発明は、ポリアリーレンスルフィド樹脂を製造方法について公知の方法であれば特に限定するものではないため、製造方法によっては該カルボキシアルキルアミノ基含有化合物が生成しない場合もあることから必須の成分ではない。しかし、例えば、１）〜５）、特に１）〜４）の重合方法で、前記カルボキシアルキルアミノ基含有化合物が生成した場合は、当該カルボキシアルキルアミノ基含有化合物は粗反応混合物と非プロトン性極性溶媒のＰＡＳ／溶媒固液分離工程を経て、反応混合物中に含まれ、さらに本発明の工程（１）を経て、前記水溶液（ａ）中に含まれ、さらに本発明の工程（２）を経て、前記水溶液（ｂ）中に含まれ、さらに工程（３）、（４）において硫化水素と分離されることとなる。すなわち、アルカリ金属ハロゲン化物と同様に移行する。このため、アルカリ金属水硫化物を生成する反応には関与せず、必須の成分ではない。

A carboxyalkylamino group-containing compound represented by the formula (wherein X represents an alkali metal atom or a hydrogen atom) may be contained in the crude reaction mixture. Since the present invention is not particularly limited as long as it is a known method for producing a polyarylene sulfide resin, it is not an essential component because the carboxyalkylamino group-containing compound may not be produced depending on the production method. . However, for example, when the carboxyalkylamino group-containing compound is produced by the polymerization method of 1) to 5), particularly 1) to 4), the carboxyalkylamino group-containing compound and the aprotic polarity are mixed with the crude reaction mixture. It is contained in the reaction mixture through the PAS / solvent solid-liquid separation step of the solvent, further through the step (1) of the present invention, further contained in the aqueous solution (a), and further through the step (2) of the present invention. , Contained in the aqueous solution (b) and further separated from hydrogen sulfide in the steps (3) and (4). That is, it migrates in the same way as the alkali metal halide. For this reason, it does not participate in the reaction for producing the alkali metal hydrosulfide and is not an essential component.

  At least polyarylene sulfide resin obtained through the above PAS polymerization step, remaining alkali metal hydrosulfide and / or alkali metal sulfide as an unreacted sulfiding agent, alkali metal halide, and aprotic polarity A crude reaction mixture containing a solvent can be used as the mixture (a).

  Next, in the PAS / solvent solid-liquid separation step, at least the polyarylene sulfide resin obtained through the PAS polymerization step, the alkali metal hydrosulfide and / or alkali metal sulfide remaining as an unreacted sulfidizing agent, The crude reaction mixture containing the alkali metal halide and the aprotic polar solvent is then subjected to solid-liquid separation of the aprotic polar solvent from the crude reaction mixture, so that at least a polyarylene sulfide resin, an alkali metal halogen is obtained. And a reaction mixture containing an alkali metal hydrosulfide and / or an alkali metal sulfide. The obtained reaction mixture can also be used as the mixture (a).

  The solid-liquid separation is roughly classified into two types, a flash method and a quench method described later. The flash method is a method of recovering a solvent by evaporating the solvent and simultaneously recovering a solid substance, and is generally performed by heating under reduced pressure to distill off the solvent.

  On the other hand, the quench method is a method in which the polymerization reaction product is removed by cooling to recover the particulate polyarylene sulfide resin. Generally, after cooling the reaction slurry in a reaction kettle, the polyarylene sulfide resin is crystallized. For example, a solid-liquid separation method may be used. Solid-liquid separation in the Quench method is a method in which after separation using a centrifugal separator such as filtration or screw decanter, water is directly added to the obtained filtration residue to form a slurry, and then solid-liquid separation is repeated. For example, a method of removing the remaining solvent by heating the filtered residue in a non-oxidizing atmosphere can be used. The flash method is preferable because solids can be recovered relatively easily, and the quench method is easy to control the particle size of the polyarylene sulfide resin, and the alkali metal halide or sulfiding agent is added to the polymer particles during crystallization. This is preferable in that a high-purity polymer is obtained.

  Subsequently, the reaction mixture is separated into a polyarylene sulfide resin and an aqueous solution containing at least an alkali metal halide and a sulfidizing agent through a purification step by water washing or hot water washing of the present invention. The said refinement | purification process can be performed similarly to a process (1), and what is necessary is just to collect | recover the polyarylene sulfide resin separated by filtration, when manufacturing a polyarylene sulfide resin.

  The polyarylene sulfide resin separated by filtration is recovered and then dried as it is, and may be used as a polyarylene sulfide resin powder. Further, after washing treatment, solid-liquid separation is performed, and drying is performed to form a powder or granule. It can also be prepared as a polyarylene sulfide resin.

  As described above, the polyarylene sulfide resin polymerized by reusing the sulfidizing agent obtained through the steps (1) to (4) of the present invention as at least a part of the raw material impairs the effects of the present invention. As long as there are no additives, additives such as a mold release agent, a colorant, a heat stabilizer, an ultraviolet stabilizer, a foaming agent, a rust inhibitor, a flame retardant, a lubricant, a coupling agent, and a filler can be contained. Furthermore, the following synthetic resins and elastomers can also be mixed and used. These synthetic resins include polyester, polyamide, polyimide, polyetherimide, polycarbonate, polyphenylene ether, polysulfone, polyethersulfone, polyetheretherketone, polyetherketone, polyarylene, polyethylene, polypropylene, polytetrafluoroethylene, Examples thereof include poly (difluoroethylene), polystyrene, ABS resin, epoxy resin, silicone resin, phenol resin, urethane resin, and liquid crystal polymer. Examples of the elastomer include polyolefin rubber, fluorine rubber, and silicone rubber.

  Furthermore, the polyarylene sulfide resin polymerized by reusing the sulfidizing agent obtained through steps (1) to (4) as at least a part of the raw material is used for injection molding, extrusion molding, compression molding and blow molding. By various melt processing methods, it is possible to produce a molded article having excellent heat resistance, molding processability, dimensional stability, etc., and particularly excellent adhesion to an epoxy resin. For this reason, for example, electrical / electronic parts such as connectors / printed boards / encapsulated molded products, automotive parts such as lamp reflectors / various electrical components, interior materials such as various buildings, aircraft / automobiles, or OA equipment parts / It can be widely used as injection molding / compression molding products such as precision parts such as camera parts and watch parts, or extrusion molding and pultrusion molding products such as fibers, films, sheets, and pipes.

  According to the present invention, by separating and recovering an alkali metal hydrosulfide remaining as an unreacted sulfiding agent in a reusable state from waste water obtained after washing with water or after washing with hot water in the production process of the polyarylene sulfide resin, It is possible to improve the productivity of the polyarylene sulfide resin by reducing the environmental load by reducing the COD value of waste water and industrial waste, and suppressing the loss of sulfur atoms (decrease in raw material basic unit).

  The present invention will be specifically described below with reference to examples. These examples are illustrative and not limiting.

(Measuring method of melt viscosity)
The polyphenylene sulfide resin produced in the synthesis example was measured after holding for 6 minutes at 300 ° C., load: 1.96 × 10 ⁶ Pa, L / D = 10/1, using a flow tester CFT-500C manufactured by Shimadzu Corporation. did.

(Quantification method of scattering S and unreacted S)
0.5 g of the sample was precisely weighed in a beaker, and then 70 ml of pure water and 4 ml of 1% sodium hydroxide aqueous solution were added, and titrated with 0.02 mol / L silver nitrate using a potentiometric automatic titrator while stirring.

(Sodium hydrosulfide concentration, determination method of sodium sulfide concentration)
Neutralization titration with 0.1 mol / L hydrochloric acid using potentiometric automatic titration device, sodium sulfide concentration is calculated from titration at the first equivalent point, then titration and second equivalent at the second equivalent point The sodium hydrosulfide concentration was calculated from the difference in the titer of the points.

Example 1
A gas absorption bottle containing 80 g of a 15 wt% sodium hydroxide aqueous solution and a condenser, a pressure gauge, and a thermometer connected with a liquid receiver were connected to a 45% sodium hydrosulfide (47.62 mass% NaSH) 588.62 g, 48 % Caustic soda (48.75 mass% NaOH) 393.85 g and N-methyl-2-pyrrolidone 1165 g were charged. While stirring under a nitrogen stream, the temperature was raised to 209 ° C. to distill 496.48 g of water (the amount of water remaining was 1.11 mol per 1 mol of NaSH). The hydrogen sulfide scattered during the dehydration was absorbed into the sodium hydroxide aqueous solution by the gas absorption bottle to obtain the sodium hydroxide aqueous solution (1) that absorbed the hydrogen sulfide.

  As a result of silver nitrate titration of the aqueous sodium hydroxide solution (1) that absorbed hydrogen sulfide, the amount of hydrogen sulfide scattered during dehydration was 0.110 mol, and the amount of recovered sulfur atoms was 2 with respect to 1 mol of sodium hydrogen sulfide charged. It was 2 mol%.

  Thereafter, the autoclave was sealed and cooled to 180 ° C., and 712.04 g of p-dichlorobenzene and 755 g of N-methyl-2-pyrrolidone were charged. The temperature was raised by pressurizing to 0.1 MPa with a gauge pressure using nitrogen gas at a liquid temperature of 150 ° C. The polymerization reaction was carried out by stirring at a liquid temperature of 250 ° C. for 2 hours.

  After the polymerization reaction, the resulting crude reaction mixture was cooled to room temperature to obtain a slurry. The slurry was heated to 120 ° C., filtered under reduced pressure, and then vacuum-dried at 150 ° C. for 3 hours. After drying, N-methyl-2-pyrrolidone was distilled off to obtain a reaction mixture.

  Next, 3780 g of 70 ° C. warm water was added to the reaction mixture and stirred, followed by filtration. Further, 1080 g of 70 ° C. warm water was added and filtered, and the filtrate was collected to obtain an aqueous solution (2). As a result of silver nitrate titration of the aqueous solution (2), the unreacted sulfur content (total of sodium sulfide and sodium hydrosulfide) was 0.167 mol (3.4 mol% with respect to the sodium hydrosulfide charged).

Subsequently, a gas absorption bottle containing an aqueous sodium hydroxide solution (1) in which hydrogen sulfide was absorbed was connected to a sealed container equipped with a stirrer, a pH meter, a gas introduction tube, and a dropping funnel. 4900 g of the aqueous solution (2) was charged into the sealed container, stirred while introducing N ₂ gas (50 ml / min), hydrochloric acid was added dropwise to adjust to pH 3.0, stirring was performed for 60 minutes, and hydrogen sulfide gas was added. This was generated and absorbed in a sodium hydroxide aqueous solution (1) in the connected gas absorption bottle to obtain a sodium hydrosulfide recovery liquid (A). The sodium hydrosulfide recovery liquid (A) had a sodium hydrosulfide concentration of 15.9% by mass and a sodium sulfide concentration of 2.0% by mass.

(Example 2)
A gas absorption bottle containing 80 g of 25% by mass aqueous sodium hydroxide solution (3) was connected to a sealed container equipped with a stirrer, pH meter, gas introduction tube, and dropping funnel. The closed vessel was charged with 4900 g of the aqueous solution (2) obtained in the same manner as in Example 1, stirred while introducing N ₂ gas (50 ml / min), and hydrochloric acid was added dropwise to adjust the pH to 3.0. The mixture was stirred for 60 minutes to generate hydrogen sulfide gas, which was absorbed into the aqueous sodium hydroxide solution (3). Without replacing the sodium hydroxide aqueous solution (3) in the gas absorption bottle, the aqueous solution (2) in the sealed container was replaced with 4900 g of the aqueous solution (2) obtained in the same manner as in Example 1, and N ₂ gas ( (50 ml / min) while stirring, hydrochloric acid was added dropwise to adjust the pH to 3.0, and the mixture was stirred for 60 minutes to generate hydrogen sulfide gas. A sodium hydroxide aqueous solution in the connected gas absorption bottle (3) To obtain a sodium hydrosulfide recovery liquid (B). The sodium hydrosulfide recovery liquid (B) had a sodium hydrosulfide concentration of 24.3% by mass and a sodium sulfide concentration of 0.6% by mass.

(Example 3)
In a 1 L autoclave connected with a gas absorption bottle containing an aqueous sodium hydroxide solution and a condenser, pressure gauge, and thermometer connected to a liquid receiver, 45% sodium hydrosulfide (47.62 mass% NaSH) 166.99 was obtained. 29 g of sodium hydrosulfide recovery liquid (A) (the proportion of sodium hydrosulfide recovered with respect to the total mole of sodium hydrosulfide used and reused as a raw material is 6.0 mol%), 48% caustic soda (48.75 mass) % NaOH) 117.54 g and N-methyl-2-pyrrolidone 349 g were charged. While stirring under a nitrogen stream, the temperature was raised to 209 ° C. to distill 166.38 g of water (the amount of water remaining was 1.13 mol per 1 mol of NaSH). The hydrogen sulfide scattered during dehydration was absorbed in the sodium hydroxide aqueous solution by the gas absorption bottle. Thereafter, the autoclave was sealed and cooled to 180 ° C., and 213.90 g of p-dichlorobenzene and 227 g of N-methyl-2-pyrrolidone were charged. The temperature was raised by pressurizing to 0.1 MPa with a gauge pressure using nitrogen gas at a liquid temperature of 150 ° C. The reaction was carried out with stirring at a liquid temperature of 250 ° C. for 2 hours. The maximum pressure during the reaction was 0.86 MPa. After the reaction, it was cooled to room temperature. 200 g of the resulting reaction slurry was heated to 100 ° C. and then filtered under reduced pressure. 1 L of pure water was added to the obtained solvent-containing cake, stirred and slurried, filtered, and 1 L of pure water was further added to the obtained water-containing cake, followed by cake washing filtration. This operation was further repeated twice, followed by drying with a hot air circulating dryer at 120 ° C. for 4 hours to obtain a PPS resin. The melt viscosity of the obtained polymer was 56 Pas.

Example 4
“166.03 g of 45% sodium hydrosulfide (47.62 mass% NaSH), 29 g of the obtained sodium hydrosulfide recovery liquid (A) (recovered with respect to the total mol of sodium hydrosulfide and recovered and reused as a raw material) Sodium hydrosulfide use ratio is 6.0 mol%), 48% caustic soda (48.75 mass% NaOH) 117.54 g ”instead of“ 45% sodium hydrosulfide (47.62 mass% NaSH) 158.40 g, Sodium hydrosulfide recovery liquid (A) 50 g (relating to the total mole of sodium hydrosulfide charged, sodium hydrosulfide used in a recycled ratio of 10.3 mol%), 48% sodium hydroxide (48.75 mass) % NaOH) 117.10 g ”was used. The polymer obtained had a melt viscosity of 57 Pas.

(Example 5)
"456.0% sodium hydrosulfide (47.62 mass% NaSH) 166.03g, obtained sodium hydrosulfide recovery liquid (A) 29g (the ratio of recovered sodium hydrosulfide used to the total mole of sodium hydrosulfide is "6.0 mol%), 48% caustic soda (48.75 mass% NaOH) 117.54 g", "45% sodium hydrosulfide (47.62 mass% NaSH) 135.09 g, sodium hydrosulfide recovery liquid (B ) Example except that 80 g (recovered sodium hydrosulfide used relative to the total mole of sodium hydrosulfide used was 23.5 mol%) and 48% caustic soda (48.75 mass% NaOH) 117.65 g ” Same as 3. The polymer obtained had a melt viscosity of 55 Pas.

(Reference Example 1)
“166.03 g of 45% sodium hydrosulfide (47.62 mass% NaSH), 29 g of the obtained sodium hydrosulfide recovery liquid (A) (recovered with respect to the total mol of sodium hydrosulfide and recovered and reused as a raw material) The sodium hydrosulfide use ratio is 6.0 mol%), and instead of 48% caustic soda (48.75 mass% NaOH) 117.54 g, “45% sodium hydrosulfide (47.62 mass% NaSH) 176.59 g, The same procedure as in Example 3 was performed except that 118.5 g of 48% caustic soda (48.75 mass% NaOH) was used. The melt viscosity of the obtained polymer was 56 Pas.

(Comparative Example 1)
To an autoclave connected with a gas absorption bottle containing 80 g of N-methyl-2-pyrrolidone and a condenser, a pressure gauge, and a thermometer connected to a liquid receiver, 176.59 g of 45% sodium hydrosulfide (47.62% by mass NaSH), 123.45 g of 48% caustic soda (48.75 mass% NaOH) and 349 g of N-methyl-2-pyrrolidone were charged. While stirring under a nitrogen stream, the temperature was raised to 209 ° C. to distill 151.49 g of water (the amount of remaining water was 1.17 mol per 1 mol of NaSH). The hydrogen sulfide scattered at the time of dehydration was absorbed into the gas absorption bottle to obtain an N-methyl-2-pyrrolidone solution (1) that absorbed hydrogen sulfide.
In addition, as a result of silver nitrate titration of the N-methyl-2-pyrrolidone solution (1) that absorbed hydrogen sulfide, the amount of hydrogen sulfide scattered during dehydration was 0.030 mol, and the recovered sulfur atoms were charged sodium hydrogen sulfide 1 It was 1.9 mol% with respect to mol.

(Comparative Example 2)
Thereafter, the autoclave was sealed and cooled to 180 ° C., and charged with 80 g of an N-methyl-2-pyrrolidone solution (1) having absorbed hydrogen sulfide, 218.11 g of p-dichlorobenzene and 148 g of N-methyl-2-pyrrolidone. . Thereafter, the same procedure as in Example 3 was performed. The polymer obtained had a melt viscosity of 55 Pas.

  From the above results, it is clear that in Examples 1 and 2, compared to Comparative Example 1, among the sulfidizing agents used as the raw materials for producing the polyphenylene sulfide resin, a large amount of the unreacted remaining sulfidizing agent can be recovered. became. Furthermore, in Examples 3 to 5, even if the sulfidizing agent recovered in Examples 1 and 2 was reused as a raw material for PPS polymerization at a high rate, it was melted in the same manner as in Reference Example 1 (normal PPS polymerization method). It became clear that a PPS resin having a viscosity can be produced.

Claims (7)

After contacting at least the mixture (a) containing the polyarylene sulfide resin, the alkali metal halide and the sulfidizing agent with water, the polyarylene sulfide resin is separated and removed, and at least the alkali metal halide and the sulfided A step (1) of obtaining an aqueous solution (b) containing an agent;
A step (2) of adding an acid to the aqueous solution (b) containing at least an alkali metal halide and a sulfidizing agent to produce hydrogen sulfide;
Recovering the produced hydrogen sulfide (3), and
A step (4) of reacting the obtained hydrogen sulfide with an alkali metal hydroxide;
To have,
A method for producing a sulfiding agent, wherein the sulfiding agent is at least one selected from the group consisting of alkali metal sulfides and alkali metal hydrosulfides . The mixture (a) comprising at least a polyarylene sulfide resin, an alkali metal halide and a sulfidizing agent is:
A crude product containing at least a polyarylene sulfide resin, an alkali metal halide, the aprotic polar solvent and a sulfidizing agent obtained after reacting a polyhaloaromatic compound with a sulfidizing agent in an aprotic polar solvent. The production method according to claim 1, which is a reaction mixture or a reaction mixture obtained by solid-liquid separation of the aprotic polar solvent from the crude reaction mixture.   A dehydration step of dehydrating the hydrous sulfiding agent in the presence of at least the aprotic polar solvent is the sulfiding agent used when the polyhaloaromatic compound and the sulfiding agent are reacted in an aprotic polar solvent. The production method according to claim 2, which is obtained through the process.   After the step (4) of reacting the obtained hydrogen sulfide with the alkali metal hydroxide, hydrogen sulfide is added to the unreacted alkali metal hydroxide, and the hydrogen sulfide and the unreacted alkali metal water are added. The manufacturing method of Claim 1 which has the process (5) made to react with an oxide.   A method for producing a sulfidizing agent, comprising: recovering hydrogen sulfide produced in the dehydration step according to claim 3 and then reacting it with an alkali metal hydroxide to obtain a sulfidizing agent.   After the step of reacting with an alkali metal hydroxide to obtain an alkali metal hydrosulfide and / or alkali metal sulfide, hydrogen sulfide is added to the unreacted alkali metal hydroxide to add the hydrogen sulfide The method for producing a sulfidizing agent according to claim 5, further comprising a step of reacting the alkali metal hydroxide of the reaction.   A polyarylene sulfide resin produced by reacting a sulfidizing agent obtained by dehydrating a hydrous sulfiding agent in the presence of an organic amide solvent with a polyhaloaromatic compound in the presence of an organic amide solvent to produce a polyarylene sulfide resin. The sulfidizing agent obtained by the production method according to any one of claims 1 to 4 and / or the sulfiding agent according to claim 5 or 6 as at least a part of the hydrous sulfiding agent or sulfiding agent. A method for producing a polyarylene sulfide resin, comprising a step of adding a sulfidizing agent obtained by the production method.