JP2020139076A - Method for producing polyarylene sulfide - Google Patents

Abstract

To provide a method for producing polyarylene sulfide, in which a PAS having a small amount of volatile gas when melted, a fast crystallization speed, and excellent features during fabrication can efficiently be yielded.SOLUTION: The method for producing polyarylene sulfide is a method for producing polyarylene sulfide including a particular step, and in which, characterized, the obtained polyarylene sulfide has the amount of gas volatilized when heated and melted at 371°C for 1 hour of 0.30 wt.% or less, and the crystallization temperature is 230°C or higher.SELECTED DRAWING: None

Description

The present invention relates to a method for efficiently producing high quality polyarylene sulfide.

Polyphenylene sulfide (hereinafter abbreviated as PPS) typified by polyphenylene sulfide (hereinafter abbreviated as PAS) has excellent heat resistance, barrier properties, chemical resistance, electrical insulation, moisture heat resistance, and other properties suitable for engineering plastics. It has and is used for various electric / electronic parts, mechanical parts and automobile parts, films, fibers, etc. mainly for injection molding and extrusion molding. There are two methods for producing PAS: a method for obtaining a powdery polymer and a method for obtaining a granular polymer. The former is a method (hereinafter referred to as a flash method) in which the polymerization reaction product is flushed (spouting the polymerization reaction product from a nozzle) at a high temperature and high pressure in the latter half of the polymerization step, which facilitates solvent recovery. The latter is a method in which the polymerization reaction product is slowly cooled in the latter half of the polymerization step to precipitate PPS in the form of granules and recovered (hereinafter referred to as a quenching method). However, in general, PAS resin has a high melting point and therefore has a high melting processing temperature, and volatile components are likely to be generated during processing. Especially when it is used for injection molding, molding defects due to mold stains and mold vent clogging occur. It may occur, and reduction of volatile components is strongly desired. Such volatile components have succeeded in obtaining PPS with reduced volatile components at the time of melting by heat-treating the PPS recovered by the flash method in an oxygen atmosphere (Patent Documents 1 to 3).

International Publication No. 2006/059509 JP-A-2007-308612 International Publication No. 2009/060524

However, the PPS obtained by the methods of Patent Documents 1 to 3 has a drawback that the crystallization rate is slow. The crystallization rate of the polymer affects the time cycle during the molding process, and if the crystallization is slow, the productivity of the molded product is inferior and it is economically disadvantageous. Therefore, a polymer having a high crystallization rate is required. An object of the present invention is to efficiently obtain PAS having a small amount of volatile gas at the time of melting, a high crystallization rate, and excellent features in molding processing.

That is, the present invention is as follows.
(1) A method for producing polyarylene sulfide, which comprises the following steps 1 to 4, wherein the amount of gas volatilized when the obtained polyarylene sulfide is heated and melted at 371 ° C. for 1 hour is 0.30% by weight or less. A method for producing polyarylene sulfide, which comprises a crystallization temperature of 230 ° C. or higher.
Step 1: A step of heating the mixture A containing an organic amide solvent, a sulfidizing agent, and a dihalogenated aromatic compound in a temperature range of 200 ° C. or higher and lower than 290 ° C.
Step 2: A step of adjusting the reaction solution containing the polymer obtained in Step 1 so that 2.0 mol or more and less than 5.5 mol of water is present per 1 mol of the sulfur component.
Step 3: A step of solid-liquid separating the reaction solution obtained in Step 2, removing fine powder and low molecular weight components, and washing the polymer recovered as a solid content with an organic solvent.
Step 4: A step of thermally oxidizing the polymer obtained in Step 3 at 220 ° C. or higher and lower than 270 ° C.
(2) The method for producing polyarylene sulfide according to (1), wherein the step 4 is subjected to thermal oxidation treatment in a state where the oxygen concentration is 2% by volume or more.
(3) The method for producing polyarylene sulfide according to (1) or (2), wherein the organic solvent used in the first step step 3 is N-methyl-2pyrrolidone.

According to the present invention, it is possible to obtain PAS having excellent fluidity at the time of melting, a small amount of volatile gas, and a high crystallization rate.

(1) PAS
The PAS in the present invention is a homopolymer or copolymer having a repeating unit of the formula, − (Ar—S) − as a main constituent unit, preferably containing 80 mol% or more of the repeating unit.

Further, the PAS in the present invention may be any of a random copolymer containing the above repeating unit, a block copolymer and a mixture thereof.

Typical examples of these include polyphenylene sulfide, polyphenylene sulfide sulfone, polyphenylene sulfide ketone, random copolymers thereof, block copolymers, and mixtures thereof. Particularly preferred PAS include polyphenylene sulfide, polyphenylene sulfide sulfone, and polyphenylene sulfide ketone containing 80 mol% or more, particularly 90 mol% or more of p-phenylene sulfide units as the main constituent unit of the polymer.

Hereinafter, the method for producing PAS of the present invention will be described.

PAS is obtained by polymerizing a sulfidizing agent and a dihalogenated aromatic compound in an organic amide solvent. These components will be described.

(2) Sulfidating agent Examples of the sulfidizing agent used in the present invention include alkali metal sulfides and alkali metal hydrosulfides. Specific examples of the alkali metal sulfide include, for example, lithium sulfide, sodium sulfide, potassium sulfide, rubidium sulfide, cesium sulfide, and a mixture of two or more of these, and sodium sulfide is preferably used. These alkali metal sulfides can be used as hydrates or aqueous mixtures, or in the form of anhydrides.

Specific examples of the alkali metal hydrosulfide include, for example, sodium hydrosulfide, potassium hydrosulfide, lithium hydrosulfide, rubidium hydrosulfide, cesium hydrosulfide, and a mixture of two or more thereof, and among them, water. Sodium sulfide is preferably used. These alkali metal hydrosulfides can be used as hydrates or aqueous mixtures, or in the form of anhydrides.

In addition, alkali metal sulfides prepared in situ in the reaction system from alkali metal hydrosulfides and alkali metal hydroxides can also be used. Alternatively, alkali metal sulfides prepared in situ in the reaction system from alkali metal hydroxides such as lithium hydroxide and sodium hydroxide and hydrogen sulfide can also be used.

In the present invention, the amount of the sulfidizing agent (hereinafter referred to as the charged sulfidating agent) present in the reaction system is actually the actual amount when a partial loss of the sulfidizing agent occurs before the start of the polymerization reaction due to dehydration operation or the like. It shall mean the residual amount obtained by subtracting the loss amount from the charged amount.

Alkaline metal hydroxides and / or alkaline earth metal hydroxides can also be used in combination with the sulfidizing agent. Specific examples of the alkali metal hydroxide include, for example, sodium hydroxide, potassium hydroxide, lithium hydroxide, rubidium hydroxide, cesium hydroxide, and a mixture of two or more of these, and alkaline earth. Specific examples of the metal hydroxide include calcium hydroxide, strontium hydroxide, barium hydroxide and the like, and sodium hydroxide is preferably used.

When alkali metal hydrosulfide is used as the sulfidizing agent, it is particularly preferable to use alkali metal hydroxide at the same time. The amount of alkali metal hydroxide used is 0.95 mol or more and less than 1.20 mol, preferably 1.00 mol or more and less than 1.15 mol, and more preferably 1.005 mol or more with respect to 1 mol of alkali metal hydrosulfide. A range of less than 1.100 mol can be exemplified.

(3) Dihalogenated Aromatic Compounds Examples of the dihalogenated aromatic compound used in the present invention include dihalogenated benzene such as p-dichlorobenzene, o-dichlorobenzene, m-dichlorobenzene and p-dibromobenzene, and 1-. Examples thereof include dihalogenated aromatic compounds containing substituents other than halogen such as methoxy-2,5-dichlorobenzene and 3,5-dichlorobenzoic acid. Of these, a dihaloated aromatic compound containing p-dihalogenated benzene as a main component, typified by p-dichlorobenzene, is preferable. Particularly preferably, it contains 80 to 100 mol% of p-dichlorobenzene. It is also possible to use two or more different dihalogenated aromatic compounds in combination to produce a PAS copolymer.

The amount of the dihalogenated aromatic compound used is 0.9 mol or more and less than 2.0 mol, preferably 0.95 mol or more, and preferably 0.95 mol or more, from the viewpoint of obtaining polyarylene sulfide having a molecular weight suitable for processing. Examples thereof include a range of less than 5 mol, more preferably 1.005 mol or more and less than 1.2 mol.

(4) Organic Amide Solvent In the present invention, an organic amide solvent is used as the polymerization solvent. Specific examples include N-alkylpyrrolidones such as N-methyl-2-pyrrolidone and N-ethyl-2-pyrrolidone, caprolactams such as N-methyl-ε-caprolactam, and 1,3-dimethyl-2-imidazolidi. Approtic organic solvents typified by non, N, N-dimethylacetamide, N, N-dimethylformamide, hexamethylphosphate triamide and the like, and mixtures thereof are preferably used because of their high reaction stability. Of these, N-methyl-2-pyrrolidone (hereinafter, may be abbreviated as NMP) is preferably used.

The amount of the organic amide solvent used in the present invention is not particularly limited, but a range of 2.5 mol or more and less than 15 mol, preferably 2.5 mol or more and less than 5.5 mol, is selected per 1 mol of the charged sulfide agent. The range of 2.7 mol or more and less than 4.5 mol is more preferable, the range of 2.7 mol or more and less than 4.0 mol is more preferable, and the range of 2.7 mol or more and less than 3.5 mol is even more preferable. Here, the amount of the organic amide solvent in the reaction system is an amount obtained by subtracting the amount of the organic amide solvent removed from the reaction system from the amount of the organic amide solvent introduced into the reaction system. If the amount of the organic amide solvent used is less than the above range, it tends to be difficult to obtain PAS with high purity. Further, when the organic amide solvent is polymerized using an amount exceeding the above range, the molecular weight is difficult to increase and the crystallization rate becomes too high, which may hinder the film formation of a particularly thick film. Further, the organic amide solvent tends to be economically disadvantageous because the reaction takes a long time if it is too much or too little.

(5) Molecular Weight Modulator, Branching / Crosslinking Agent In the present invention, a molecular weight modifier (not necessarily aromatic) such as a monohalogen compound is used to form the terminal of the produced PAS, or to regulate the polymerization reaction or molecular weight. (It does not have to be a compound) can be used in combination with the above dihalogenated aromatic compound. Further, in order to form a branched or crosslinked polymer, a polyhalogen compound having a trihalogenation or higher (not necessarily an aromatic compound), an active hydrogen-containing halogenated aromatic compound, a halogenated aromatic nitro compound, or the like is branched. -It is also possible to use a cross-linking agent together. As the polyhalogen compound, a commonly used compound can be used, but a polyhalogenated aromatic compound is preferable, and specific examples thereof include 1,3,5-trichlorobenzene, 1,2,4-trichlorobenzene, and the like. Examples thereof include 1,2,4,5-tetrachlorobenzene, hexachlorobenzene and 1,4,6-trichloronaphthalene, with 1,3,5-trichlorobenzene and 1,2,4-trichlorobenzene being preferred. Examples of the active hydrogen-containing halogenated aromatic compound include halogenated aromatic compounds having functional groups such as an amino machine, a mercapto group and a hydroxyl group. Specific examples include 2,5-dichloroaniline, 2,4-dichloroaniline, 2,3-dichloroaniline, 2,4,6-trichloroaniline, 2,2'-diamino-4,4'-dichlorodiphenyl ether, 2 , 4'-diamino-2', 4-dichlorodiphenyl ether and the like. Examples of the halogenated aromatic nitro compound include 2,4-dinitrochlorobenzene, 2,5-dichloronitrobenzene, 2-nitro-4,4'-dichlorodiphenyl ether, and 3,3'-dinitro-4,4'-. Examples thereof include dichlorodiphenylsulfone, 2,5-dichloro-2-nitropyridine and 2-chloro-3,5-dinitropyridine.

(6) Polymerization Aid In the present invention, it is preferable to use a polymerization aid in order to obtain a high molecular weight PAS in a shorter time. Here, the polymerization aid refers to a substance having an action of increasing the molecular weight of the obtained PAS. Specific examples of such polymerization aids include organic carboxylates, water, alkali metal chlorides, organic sulfonates, alkali metal sulfates, alkaline earth metal oxides, alkali metal phosphates, and alkalis. Examples include earth metal phosphates. These can be used alone or in combination of two or more. Among these, an organic carboxylate and water are preferably used, and an organic carboxylate is more preferably used.

The organic carboxylate is a general formula R (COOM) _n (in the formula, R is an alkyl group, a cycloalkyl group, an aryl group, an alkylaryl group or an arylalkyl group having 1 to 20 carbon atoms. It is an alkali metal selected from lithium, sodium, potassium, rubidium and cesium. N is a compound represented by an integer of 1 to 3). The organic carboxylate can also be used as a hydrate or an aqueous solution. Specific examples of the organic carboxylate include, for example, lithium acetate, sodium acetate, potassium acetate, sodium propionate, lithium acetate, sodium benzoate, lithium phenylacetate, sodium phenylacetate, potassium p-toluic acid, and mixtures thereof. And so on. The organic carboxylate is formed by adding an organic acid and one or more compounds selected from the group consisting of alkali metal hydroxides, alkali metal carbonates and alkali metal bicarbonates in approximately equal chemical equivalents and reacting them. It may be formed. Among the above organic carboxylates, it is presumed that the lithium salt has high solubility in the reaction system and is highly effective as a polymerization aid but is expensive, and the potassium, rubidium and cesium salts are inferior in solubility in the reaction system. Sodium acetate, which is inexpensive and has an appropriate solubility in the reaction system, is preferably used.

The amount of these polymerization aids used is preferably in the range of 0.1 mol or more and less than 0.25 mol, more preferably in the range of 0.1 mol or more and less than 0.2 mol, with respect to 1 mol of the charged sulfidizing agent. If it is less than the above range, the high molecular weight increasing effect is insufficient, and if it exceeds the above range, not only a higher high molecular weight increasing effect cannot be obtained, but also an adverse effect may occur depending on the polymerization time.

These polymerization aids may be contained in the reaction system at least in step 2 described later. Therefore, the addition time may be any time as long as it is before the step 2.

(7) Polymerization Stabilizer In the present invention, a polymerization stabilizer can be used in order to stabilize the polymerization reaction system and prevent side reactions. The polymerization stabilizer contributes to the stabilization of the polymerization reaction system and suppresses unwanted side reactions. One guideline for the side reaction is the production of thiophenol, and the production of thiophenol can be suppressed by adding a polymerization stabilizer. Specific examples of the polymerization stabilizer include compounds such as alkali metal hydroxides, alkali metal carbonates, alkaline earth metal hydroxides, and alkaline earth metal carbonates. Among them, alkali metal hydroxides such as sodium hydroxide, potassium hydroxide, and lithium hydroxide are preferable. Since the above-mentioned organic carboxylate also acts as a polymerization stabilizer, it is one of the polymerization stabilizers used in the present invention.

These polymerization stabilizers can be used alone or in combination of two or more. The polymerization stabilizer is usually 0.01 mol or more and less than 0.2 mol, preferably 0.03 mol or more and less than 0.1 mol, and more preferably 0.05 mol or more and 0. Use in proportions of less than 09 moles. If this ratio is small, the stabilizing effect is insufficient, and if it is too large, it is economically disadvantageous and the polymer yield tends to decrease. The time for adding the polymerization stabilizer can be selected as desired, but it is preferably before the dehydration step or at the start of polymerization. If a part of the alkali metal sulfide is decomposed during the dehydration operation to generate hydrogen sulfide, the resulting alkali metal hydroxide can also be a polymerization stabilizer.

(8) Preliminary step Prior to step 1 (polymerization step), a sulfur source, a dihalogenated aromatic compound and an organic polar solvent, and if necessary, a polymerization stabilizer and a polymerization aid are added to the fully mixed reactor, preferably. In an inert gas atmosphere, the dehydration reaction may be carried out in the range of room temperature to 220 ° C. to adjust the amount of water in the reaction system. The fully mixed reactor here includes an autoclave.

The water content of the reaction system referred to here is the amount obtained by subtracting the water content removed from the reaction system from the water introduced into the reaction system as an aqueous solution and a hydrate at the time of charging the raw materials. This amount is not particularly limited, but is particularly preferably in the range of 0 mol or more and less than 2.00 mol with respect to 1.00 mol of the sulfidizing agent from the viewpoint of polymerization rate and suppression of by-products.

(9) Step 1 (Polymerization reaction step)
In the present invention, the sulfidizing agent and the dihalogenated aromatic compound are heated and reacted in an organic polar solvent in a temperature range of 200 ° C. or higher and lower than 290 ° C. When starting the polymerization reaction step, a sulfidizing agent and a polyhalogenated aromatic compound are mixed in an organic polar solvent, preferably in an inert gas atmosphere at room temperature to 220 ° C., preferably 100 ° C. or higher and lower than 220 ° C. Add. A polymerization aid may be added at this stage. The order in which these raw materials are charged may be random or simultaneous. The temperature of such a mixture is raised to 200 ° C. or higher and lower than 290 ° C. The rate of temperature rise is not particularly limited, but a rate of 0.01 to 5 ° C./min is usually selected, and a range of 0.1 to 3 ° C./min is more preferable. In general, the temperature is finally raised to a temperature of 250 or more and less than 290 ° C., and the temperature is usually 0.25 to 50 hours, preferably 0. React for 5 or more and less than 20 hours. A method of reacting at 200 ° C. or higher and lower than 260 ° C. for a certain period of time before reaching the final temperature and then raising the temperature to 270 ° C. or higher and lower than 290 ° C. is effective in obtaining a higher degree of polymerization. At this time, the reaction time at 200 ° C. or higher and 260 ° C. is usually selected in the range of 0.25 hours to 20 hours, preferably in the range of 0.25 to 10 hours.

(10) Step 2 (Recovery step)
In the method for producing a PAS resin of the present invention, after the completion of step 1 (polymerization reaction step), a solid substance is recovered from the polymerization reaction product containing a polymer component, a solvent and the like (recovery step). Granular particles of the polymer component are added by adding water so that 2.0 mol or more and less than 5.5 mol of water is present per 1 mol of the sulfur component of the sulfidizing agent in a state where the monomer consumption reaction is completed in the polymerization step. Precipitate as. When the amount of water in the system is less than 2.0 mol per mol of the sulfur component, the precipitated polymer particles are small, and a sufficient cleaning effect cannot be exhibited in the subsequent cleaning step, and the yield is not recovered by the filter. It causes deterioration. If the amount is 5.5 mol or more, the precipitated polymer particles become large and block in the pipe, which is not preferable for operation.

(11) Step 3 (cleaning step)
In the present invention, the reaction solution containing the polymer particles precipitated in step 2 is solid-liquid separated by an 80 mesh filter, and the obtained solid substance is washed with an organic solvent.

Specific examples of the method for cleaning the PAS resin with an organic solvent include the following methods. The organic solvent used for cleaning is not particularly limited as long as it does not have an action of decomposing PAS resin, but for example, a nitrogen-containing polar solvent such as N-methyl-2-pyrrolidone, dimethylformamide, or dimethylacetamide, or dimethyl. Sulfoxide-sulfone solvents such as sulfoxide and dimethyl sulfone, ketone solvents such as acetone, methyl ethyl ketone, diethyl ketone and acetophenone, ether solvents such as dimethyl ether, dipropyl ether and tetrahydrofuran, chloroform, methylene chloride, trichloroethylene, ethylene dichloride, Halogen solvents such as dichloroethane, tetrachloroethane, chlorobenzene, alcohol / phenol solvents such as methanol, ethanol, propanol, butanol, pentanol, ethylene glycol, propylene glycol, phenol, cresol, polyethylene glycol, benzene, toluene, xylene Examples thereof include aromatic hydrocarbon solvents such as. Among these organic solvents, it is preferable to use N-methyl-2-pyrrolidone, acetone, dimethylformamide, chloroform and the like. Moreover, these organic solvents are used in one kind or a mixture of two or more kinds.

As a method of cleaning with an organic solvent, there is a method of immersing the PAS resin in the organic solvent, and if necessary, stirring or heating can be performed as appropriate.

The cleaning temperature when cleaning the PAS resin with an organic solvent is not particularly limited, and any temperature can be selected from normal temperature to less than 300 ° C. The higher the cleaning temperature, the higher the cleaning efficiency tends to be, but usually, a sufficient effect can be obtained at a cleaning temperature of room temperature or higher and lower than 150 ° C.

As for the ratio of polyarylene sulfide to the organic solvent, it is preferable that the amount of the organic solvent is large, but usually, a bath ratio of 2 times or more and less than 5 times per weight of the polymer is selected. If the bath ratio is less than 2 times, the cleaning and removal of impurities in the polymer is insufficient, and if the bath ratio is 5 times or more, the load of recovering the organic solvent used for cleaning becomes large, which is economically disadvantageous. ..

Further, the PAS resin that has been washed with an organic solvent is preferably washed with water or warm water several times in order to remove the residual organic solvent.

As a method for washing the polyarylene sulfide with water or warm water, there is a method such as immersing the polyarylene sulfide in water or warm water, and it is also possible to appropriately stir or heat it if necessary. The washing temperature when washing the polyarylene sulfide with water or warm water is preferably 20 ° C. or higher and lower than 220 ° C., and more preferably 50 ° C. or higher and lower than 200 ° C. If the temperature is lower than 20 ° C, it becomes difficult to remove by-products, and if the temperature is 220 ° C or higher, the pressure becomes high, which is not preferable for safety.

(12) Drying Treatment The PAS resin thus obtained is preferably dried under normal pressure or reduced pressure. As the drying temperature, a range of 120 or more and less than 280 ° C. is selected, and a range of 140 or more and less than 250 ° C. is more preferable. The dry atmosphere may be an inert atmosphere such as nitrogen, helium or under reduced pressure, an oxidizing atmosphere such as oxygen or air, or a mixed atmosphere of air and nitrogen, but it is preferably performed under reduced pressure, especially under normal pressure. After drying to remove water and the like, it is preferable to dry again under reduced pressure. The drying time is selected from 0.5 hours or more and less than 50 hours, preferably 1 hour or more and less than 30 hours, and more preferably 1 hour or more and less than 20 hours.

(13) Step 4 (thermal oxidation treatment)
The heating device for the thermal oxidation treatment may be a normal hot air dryer or a heating device with a rotary type or a stirring blade, but for efficient and more uniform processing, a rotary type or a heating device with a stirring blade may be used. It is more preferable to use the heating device of. The oxygen concentration during the thermal oxidation treatment is preferably 2% by volume or more. The upper limit of the oxygen concentration is not particularly limited, but is limited to about 50% by volume, more preferably 25% by volume or less. The temperature condition of the thermal oxidation treatment is 220 ° C. or higher and lower than 270 ° C., preferably 220 ° C. or higher and lower than 230 ° C. Below 220 ° C., the oxidation rate of polyarylene sulfide is slow, which is disadvantageous in terms of productivity. At 270 ° C. or higher, the temperature is close to the melting point of polyarylene sulfide, so that polyarylene sulfide partially starts to melt, which becomes a foreign substance during subsequent processing and molding, which is not preferable.

(14) PAS
The PAS obtained in the present invention has a gas amount (gas generation amount) of 0.30% by weight or less when it is heated and melted at 371 ° C. for 1 hour. More preferably, it is 0.25% by weight or less. By setting the amount of gas generated to 0.30% by weight or less, dirt on the base used in the molding process is reduced, and the productivity of the molding process is improved. The lower limit of the amount of gas generated is not particularly limited, but it is economically disadvantageous if the thermal oxidation treatment time is lengthened for the purpose of reducing the amount of gas generated.

The amount of gas generated by PAS in the present invention is determined by measuring PAS in an aluminum cup, inserting the aluminum cup into an electric tube furnace, heating at 371 ° C. for 1 hour, removing the sample from the electric tube furnace, and then in a desiccator. Allow to cool for at least 30 minutes and weigh. The ratio of the weight difference before and after heating to the weight of the sample before heating by the electric tube furnace was defined as the amount of gas generated.

The PAS obtained in the present invention has a crystallization temperature of 230 ° C. or higher. If the temperature is 230 ° C. or higher, the time from the molten state to solidification is short, and the time cycle of the molding process can be shortened, which is economically advantageous. The preferred range is that the crystallization temperature is 230 ° C. or higher and lower than 240 ° C. If it exceeds 240 ° C., the time from the molten state to the solidification is short, and the molding stability is lacking, which is not preferable.

The crystallization temperature in the present invention is a temperature measured using a differential scanning calorimeter (DSC). Approximately 10 mg of PAS was weighed in a nitrogen atmosphere, and the temperature was raised from room temperature to 340 ° C at a temperature raising / lowering rate of 20 ° C./min. The crystallization peak temperature observed when the temperature is warmed and lowered to 100 ° C. is defined as the crystallization temperature (Tmc).

Hereinafter, the method of the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples. The method for measuring each physical property of PAS is as follows.

(1) Amount of gas generated After measuring 5 g of PPS resin in an aluminum cup having a capacity of 60 ml, it was inserted into an electric tube furnace (Yamato Scientific FO810) and heated at 371 ° C. for 1 hour. After taking out the sample from the electric tube furnace, it was allowed to cool in a desiccator (Inuchi Seieidou ND-1) for 30 minutes or more and weighed. The ratio of the weight difference before and after heating to the weight of the sample before heating by the electric tube furnace was defined as the amount of gas generated.

(2) Measurement of crystallization temperature Using pyris1 DSC manufactured by Perkin Elmer, the temperature is raised from room temperature to 340 ° C at a sample volume of about 10 mg, a nitrogen atmosphere, a temperature rise / fall rate of 20 ° C./min, and 1 at 340 ° C. The temperature was held for 1 minute, the temperature was lowered to 100 ° C., the temperature was raised to 340 ° C. again, and the crystallization peak temperature when the temperature was lowered to 100 ° C. was defined as the crystallization temperature (Tmc).

[Reference Example 1] Preparation of PPS-1 Preliminary step In a tank equipped with a stirrer, 8237.4 g (70.0 mol) of 48% sodium hydrosulfide, 2933.3 g (70.4 mol) of 96% sodium hydroxide, N- Methyl-2-pyrrolidone (NMP) 11454.1 g (115.5 mol), sodium acetate 512.5 g (6.25 mol), gradually heated to 225 ° C. over about 1 hour while passing nitrogen under normal pressure to add 7807 g of water. After distilling off, the reaction vessel was cooled to 160 ° C.

Step 1 (polymerization step)
Next, 10825.1 g (73.6 mol) of p-dichlorobenzene (p-DCB) and 9169.5 kg (92.5 mol) of NMP were added. Subsequently, the reaction vessel was sealed under nitrogen gas, the temperature was raised from 200 ° C. to 275 ° C. with stirring, and the temperature was maintained at 275 ° C. for 70 minutes.

Process 2 (recovery process)
2669.3 g of water was added to the reaction mixture obtained in step 1 and the mixture was cooled to 160 ° C. to precipitate polymer particles.

Process 3 (cleaning process)
The reaction solution containing the polymer particles precipitated in step 2 was solid-liquid separated by an 80 mesh filter, and the obtained solid was washed with NMP at 95 ° C. in a liquid amount having a polymer weight ratio of 2.9.

Drying Step The polymer obtained in Step 3 was dried under a nitrogen atmosphere at 160 ° C. to obtain PPS-1.

[Reference Example 2] Preparation of PPS-2 Pre-stage In a tank equipped with a stirrer, 8207.4 g (70.0 mol) of 48% sodium hydrosulfide, 2952.0 g (70.8 mol) of 96% sodium hydroxide, N- Methyl-2-pyrrolidone (NMP) 11695.1 g (118.0 mol), sodium acetate 1205.1 g (14.7 mol), gradually heated to 225 ° C. over about 1 hour while passing nitrogen under normal pressure, and water 9461. After distilling out 4 g, the reaction vessel was cooled to 160 ° C.

Polymerization Step Next, 10447.6 g (71.1 mol) of p-dichlorobenzene (p-DCB) and 8280.9 g (83.5 mol) of NMP were added. Subsequently, the reaction vessel was sealed under nitrogen gas, heated from 200 ° C. to 275 ° C. with stirring, held at 275 ° C. for 70 minutes, and flushed.

Cleaning step The polymer obtained by flushing was washed with water by reslurry and rinse, and solid-liquid separated with a filter to recover the polymer.

Drying Step The recovered polymer was dried under a nitrogen atmosphere at 160 ° C. to obtain PPS-2.

[Examples 1 and 2]
PPS-1 was subjected to thermal oxidation treatment (step 4) under the conditions shown in Table 1, and the amount of gas generated and the crystallization temperature of the obtained PPS resin were measured. The results are shown in Table 1.

[Comparative Examples 1 and 2]
In Comparative Example 1, PPS-1 was not subjected to thermal oxidation treatment (step 4). In Comparative Example 2, PPS-2 was subjected to thermal oxidation treatment (step 4) under the conditions shown in Table 1. The amount of gas generated and the crystallization temperature of the obtained PPS resin were measured. The results are shown in Table 1.

Claims (3)

A method for producing polyarylene sulfide, which comprises the following steps 1 to 4, wherein the amount of gas volatilized when the obtained polyarylene sulfide is heated and melted at 371 ° C. for 1 hour is 0.30% by weight or less and crystallizes. A method for producing polyarylene sulfide, characterized in that the temperature is 230 ° C. or higher.
Step 1: A step of heating a mixture A containing an organic amide solvent, a sulfidizing agent, and a dihalogenated aromatic compound in a temperature range of 200 ° C. or higher and lower than 290 ° C.
Step 2: A step of adjusting the reaction solution containing the polymer obtained in Step 1 so that 2.0 mol or more and less than 5.5 mol of water is present per 1 mol of the sulfur component.
Step 3: A step of solid-liquid separating the reaction solution obtained in Step 2, removing fine powder and low molecular weight components, and washing the polymer recovered as a solid content with an organic solvent.
Step 4: A step of thermally oxidizing the polymer obtained in Step 3 at 220 ° C. or higher and lower than 270 ° C. The method for producing polyarylene sulfide according to claim 1, wherein in the step 4, thermal oxidation treatment is performed in a state where the oxygen concentration is 2% by volume or more. The method for producing polyarylene sulfide according to claim 1 or 2, wherein the organic solvent used in the step 3 is N-methyl-2pyrrolidone.