KR102118356B1 - recovery method of poly phenylne sulfide and N-Methyl-2-pyrrolidone from poly phenylene sulfide waste - Google Patents

Abstract

The present invention is a poly phenylene sulfide (Poly Phenylene Sulfide) comprising a first dilution step, the first filtration step, the second dilution step, the second filtration step, the third dilution step, and the third filtration step N-Methyl-2-pyrrolidone (N-Methyl-2-pyrrolidone) relates to a recovery method.
In the first dilution step, 6000 parts by weight of an organic solvent is mixed and diluted with respect to 10000 parts by weight of poly phenylene sulfide mixed waste. In the first filtration step, the mixed solution of the first dilution step is filtered to recover poly phenylene sulfide. In the second dilution step, water is mixed with the filtrate of the first filtrate and diluted. In the second filtration step, the mixed solution of the second dilution step is filtered to recover poly phenylene sulfide. In the third dilution step, an organic solvent is mixed and diluted in the filtrate of the second filtration step. Subsequent steps are carried out through an acidity adjustment step to increase the recovery efficiency and a dilution and filtration step of the organic solvent and water to obtain poly phenylene sulfide.
According to the present invention, poly phenylene sulfide (Poly Phenylene Sulfide) and N-methyl-2-pyrrolidone (N-Methyl-2-pyrrolidone) are recovered from poly Phenylene Sulfide mixed waste which is difficult to recycle. By doing so, it has an excellent effect of environmental friendliness and economic efficiency.

Description

Poly Phenylene Sulfide and Poly-Phenylene Sulfide and N-Methyl-2-pyrrolidone Recovery Method of poly phenylne sulfide and N-Methyl-2-pyrrolidone from poly phenylene sulfide waste}

The present invention relates to a method for recovering poly phenylene sulfide (N-Methyl-2-pyrrolidone) and its solvent, polyphenylene, which is difficult to recycle. Poly Phenylene Sulfide It relates to a method for recovering poly phenylene sulfide and N-methyl-2-pyrrolidone, an organic solvent, from waste mixed waste.

In general, poly phenylene sulfide (Poly Phenylene Sulfide) resin has excellent flame retardancy, has chemical resistance to most solvents, and has excellent dimensional stability compared to other thermoplastic resins, requiring precision injection as well as automobiles, electronics, and electrical parts. It can be applied to various industries such as connectors and gears. Moreover, as the range of use has recently been expanded to automobile parts, the interest of poly phenylene sulfide resins is increasing day by day.

(1) Poly Phenylene Sulfide resin

The poly phenylene sulfide (Poly Phenylene Sulfide) resin referred to in the present invention is a polymer having a repeating unit represented by the following [Formula 1],

From the viewpoint of heat resistance, a coalescence containing 70 mol% or more, and more preferably 90 mol% or more of the coalescence containing the repeating units represented by the above structural formula is preferred. In addition, poly phenylene sulfide (Poly Phenylene Sulfide) resin may be composed of a repeating unit or the like having a structure of less than 30 mol% of the repeating unit.

Currently, several companies have commercialized the polymerization of poly phenylene sulfide, and several polymerization methods other than the Philips method have been proposed, but the currently industrialized method is basically in the category of the Philips method. When Philips was commercialized, it was difficult to straighten the high molecular weight and was limited to coating applications.However, afterwards, a method of improving the weakness by increasing the viscosity through oxidation crosslinking appeared. This makes it possible to apply to injection molding applications.

It is already known to develop a method for polymerizing a poly phenylene sulfide resin to gradually cool it after polymerization to obtain a granular form of poly phenylene sulfide resin. However, at this time, addition of solids of microparticles mainly containing a low molecular weight poly phenylene sulfide oligomer also occurs. In addition, in most cases, the solids of the fine particles are complicated to handle, and thus, for example, a filter coated with a filter aid generates a mixture of the recovered filter aid and the particulate solid.

However, the mixed waste containing the discarded poly phenylene sulfide (Poly Phenylene Sulfide) oligomer generated during the polymerization process for producing the polyphenylene sulfide resin is a poly phenylene sulfide (Poly Phenylene Sulfide) and a solvent as shown in Table 1 As a waste after recovery, it is impossible to recycle due to low purity of poly phenylene sulfide and solvent, so it is disposed of as an oil phase.

Chemical composition of poly phenylene sulfide mixed waste
ingredient
unit
Oil content (with fluctuation)
Remark
NMP
wt. %
14
N-Methyl-2-pyrrolidone
H²O
wt. %
30
NaCl
wt. %
5
SiO²
wt. %
23
HEX
wt. %
0.2
PPS/PPS oligomer
wt. %
29
PCBs
wt. %
0.1>

If the polyphenylene sulfide (Poly Phenylene Sulfide) oligomer contained in the mixed waste of the polyphenylene sulfide (Poly Phenylene Sulfide) is contained as a main component, it can be efficiently recovered and reused. It will be very good as an enemy.

The present invention was made to solve the problems as described above, the object of the present invention is a poly phenylene sulfide (Poly Phenylene Sulfide) poly phenylene sulfide (Poly Phenylene Sulfide) generated from the polymerization reaction poly phenylene sulfide from polyphenylene sulfide ( Poly Phenylene Sulfide) and N-methyl-2-pyrrolidone (N-Methyl-2-pyrrolidone) to provide an efficient and economical recovery method.

The method for recovering the solvent of polyphenylene sulfide and N-methyl-2-pyrrolidone (N-Methyl-2-pyrrolidone) according to the present invention for achieving the above object is

(1) At least granular polyphenylene sulfide obtained by heating a mixture containing at least a polyhalogenated aromatic compound, a sulfide agent and an organic polar solvent to polymerize a poly phenylene sulfide resin to cool to 220° C. or lower (Poly Phenylene Sulfide) is a method of separating and recovering poly phenylene sulfide oligomer from mixed waste slurry (A) containing oligomer, organic polar solvent, water and halogenated alkali metal salt, and adding acid as a separation and recovery process Method for separating and recovering poly phenylene sulfide oligomers, characterized in that

(2) A method of separating and recovering poly phenylene sulfide oligomer from the mixed waste slurry (A)

(a) mixed waste slurry (A) 0.5 to 10 moles of an organic polar solvent is added to 1 mole of sulfide agent used for polymerization to form a diluted slurry (B),

(b) A dilution slurry (B) to obtain a recovered slurry (C) containing at least granular poly phenylene sulfide oligomer and organic polar solvent, water and a halogenated alkali metal salt.

(c) removing at least 50% by weight of organic polar solvent from the recovery slurry (C) to obtain a residue,

(d) At least the remaining organic polar solvent and halogenated alkali metal salt are removed from the water slurry (D) formed by adding water to the residual water,

Polyphenylene sulfide (Poly Phenylene) according to (1), characterized in that an acid is added to the recovered slurry (C) and/or water slurry (D) in a separation and recovery process to obtain a poly phenylene sulfide oligomer. Sulfide) oligomer recovery method

(3) Recovery of the poly phenylene sulfide (Poly Phenylene Sulfide) oligomer according to (2), characterized in that the pH of the recovered slurry (C) and/or the water slurry (D) is adjusted to 3 to 8 by adding an acid. Way

(4) (c) heating to remove the organic polar solvent (2) or (3) poly phenylene sulfide (Poly Phenylene Sulfide) oligomer recovery method described in

(5) Polyphenylene sulfide according to any one of (4) to (2) to remove residual organic polar solvent and halogenated alkali metal salt by decantation after filtration and/or centrifugation in step (d). Oligomer recovery method

(6) The poly phenylene sulfide according to any one of (2) to (5), wherein the step (d) is repeated at least twice and at least once is added to the water slurry (D). Sulfide) oligomer recovery method

(7) The organic polar solvent is N-methyl-2-pyrrolidone (N-Methyl-2-pyrrolidone) (1) to (7) of any one of the anti-phenylene sulfide (Poly Phenylene Sulfide) oligomer recovery method

(8) (1) to (7) to provide a method for producing a recycled poly phenylene sulfide (Poly Phenylene Sulfide) resin to reuse the poly phenylene sulfide (Poly Phenylene Sulfide) oligomer recovered by any one of the methods described in (7) .

According to the present invention, poly phenylene sulfide (Poly Phenylene Sulfide) and N-methyl-2-pyrrolidone (N-Methyl-2-pyrrolidone) from poly phenylene sulfide (Poly Phenylene Sulfide) mixed waste generated during the polymerization process It has the effect of recovering efficiently and economically.

According to the poly phenylene sulfide (N-Methyl-2-pyrrolidone) recovery method according to the present invention, it is possible to recycle the waste, so it has excellent environmental friendliness and economical efficiency. It works.

1 is a flow chart showing a poly phenylene sulfide (Poly Phenylene Sulfide) and N- methyl-2-pyrrolidone (N-Methyl-2-pyrrolidone) recovery method according to an embodiment of the present invention.
FIG. 2 is a flow chart showing a subsequent process for the filtrate of the third filtration step of FIG. 1.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Note that, in this case, in the accompanying drawings, the same components are denoted by the same reference numerals as possible. In addition, detailed descriptions of well-known functions and configurations that may obscure the subject matter of the present invention will be omitted. For the same reason, some components in the accompanying drawings are exaggerated, omitted, or schematically illustrated.

1 is a flow chart showing a method for recovering poly phenylene sulfide (Poly Phenylene Sulfide) according to an embodiment of the present invention.

As shown, the first dilution step (S100), the first filtration step (S200), the second dilution step (S300), the second filtration step (S400), and the third dilution according to the embodiment of the present invention Step S500 is included.

In the method for producing a poly phenylene sulfide (Poly Phenylene Sulfide) resin already disclosed, after the polymerization is completed, the solids are recovered from the polymerization reaction including a polymer, a solvent and the like. Poly phenylene sulfide (Poly Phenylene Sulfide) resin may employ any known recovery method, but in the sense of obtaining a granular form of poly phenylene sulfide (Poly Phenylene Sulfide) resin, a method of gradually recovering the cooled particulate polymer after completion of the polymerization reaction This is desirable. The method of removing some or all of the moisture in the polymerization tank by applying an event to the polymer particle polymerization tank is a preferred method in the sense of simplifying the following solvent recovery process.

[Method for recovering poly phenylene sulfide oligomer from waste mixture]

After recovering the poly phenylene sulfide resin by the above method, the polyphenylene sulfide oligomer in the form of fine powder, organic polar solvent, water, by-product halogenated alkali metal salt, and optionally a polymerization aid are prepared. A waste mixed waste slurry (A) containing at least is obtained.

The present invention is a method for separating and recovering poly phenylene sulfide oligomer from waste mixed waste slurry (A), and is characterized by adding acid in one step of separating and recovering. The basic method used in the present invention will be described in more detail below.

In the first dilution step (S100), it is preferable to first dilute the waste mixed waste slurry (A) with an organic solvent to form a dilution slurry (B). By diluting, the viscosity of the waste mixed waste slurry (A) is low, so that the recovery efficiency of poly phenylene sulfide resin by filtration in the step (b) below increases. At this time, the amount of the organic polar solvent used for dilution is in the range of 0.5 to 10 mol with respect to 1 mol of the sulfide agent used for polymerization, and preferably in the range of 0.7 to 5 mol.

The organic polar solvent used for dilution is preferably the same as the polymerization solvent. In addition, sulfoxide-sulfone-based solvents such as dimethylsulfoxide, dimethylsulfone, and sulfolane, acetone, and methyl ethyl ketone , Ketone-based solvents such as diethyl ketone, acetophenone, dimethyl ether, dipropyl ether, dioxan, tetrahydrofuran, etc. Ether solvent, chloroform, methylene chloride, trichloroethylene, ethylene dichloride, perchlorvethylene, monochloroethane, dichloroethane, Halogen-based solvents such as tetrachloroethane, parklorethane, and chlorobenzene, methanol, methanol, ethanol, propanol, butanol, and pentanol ), ethylene glycol (ethylene glycol), propylene glycol (propylene glycol), phenol (phenol), cresol (cresol), polyethylene glycol (polyethylene glycol), polypropylene (polypropylene) glycol (glycol) alcohol (alcohol) phenol (glycol) Phenolic) solvents are good, but dilution with a solvent other than a polymerization solvent such as water requires separation from the polymerization solvent, and separation of the two substances by using a solvent having high affinity with a polymerization solvent such as water It is economically disadvantageous to require a significant amount of energy.

In the first filtration step (S200), poly phenylene sulfide is recovered from the slurry (B). At this time, in the diluent slurry (B), poly phenylene sulfide (Poly Phenylene Sulfide) exists in a solid state, and poly phenylene sulfide (Poly Phenylene Sulfide) oligomer, water, and halogenated alkali metal salt are dispersed in an organic solvent, so known separation Poly phenylene sulfide (Poly Phenylene Sulfide) can be recovered by. At this time, the diluting slurry contains by-products during polymerization of the polymerization aid. The recovery of poly phenylene sulfide (Poly Phenylene Sulfide) is preferably a method by filtration. Filtration of granular polyphenylene sulfide by filtering at least polyphenylene sulfide oligomers, organic polar solvents, water, alkali metal halide salts, and optionally polymerization aids, byproducts, etc. Get

The temperature of the slurry (B) during filtration is not particularly limited, but a range of 50 to 200°C is usually selected, and a range of 60 to 150°C is more preferable.

At this time, the medium used can separate poly phenylene sulfide in the form of granules, including poly phenylene sulfide oligomer, organic polar solvent, water, and by-product alkali metal halide. The slurry needs to be selected to pass. In general, 10 mesh (filtration interval 1.651mm) ~ 200 mesh (filtration interval 0.074mm), preferably 48 mesh (filtration interval 0.295mm) ~ 100 mesh (filtration interval 0.147mm) is preferred. Examples of the filter include a centrifugal filtration, screening equipment, and the like, but are not limited thereto.

(c) The organic polar solvent is removed from the recovered slurry (C) obtained in (b) above. The removal of the organic polar solvent is preferably a method of heating and treating under normal pressure or reduced pressure. Removal of the organic polar solvent removes at least 50% by weight or more, preferably at least 70% by weight, more preferably at least 90% by weight of the organic polar solvent. As a temperature for volatilization removal, a range of 120°C to 300°C is usually selected, and 140°C to 250°C is more preferable. At this time, the water contained in the recovered slurry (C) is volatilized and removed at the same time. A method of depressurizing can also be used when removing the organic polar solvent.

(d) In the second dilution step (S300), water is added to the residue (D) obtained by the process (c), and the residue (D) is water-slurryed, followed by the second filtration step (S400). By a method such as filtration, at least the remaining organic polar solvent, a halogenated alkali metal halide, and a part of by-products and a polymerization aid in some cases are removed to obtain a poly phenylene sulfide (Poly Phenylene Sulfide). The amount of 0.5 to 5 g is selected for 1 g of the recovered slurry (C), and a range of 0.7 to 2.5 g is preferable. If the quantity is too small, it takes too much time for filtration, and if it is too large, the amount of wastewater increases, which is not preferable. Although the temperature of the water slurry at the time of filtration is not particularly limited, a range of 50 to 200°C is usually suitable, and a range of 60 to 100°C is more preferable. The filter medium used for filtration is a filtration interval of a degree capable of filtration recovery of poly phenylene sulfide oligomers, which is generally 1 μm to 100 μm, preferably 2 μm to 50 μm. Filters include, but are not limited to, suction filters, pressure filters, and the like. The filtration step (d) is preferably performed twice or more in order to obtain a higher purity poly phenylene sulfide oligomer.

It is preferable not to add more than 1 kg of water per 1 kg of dry poly phenylene sulfide to the slurry (A) or dilute slurry (B) at a temperature of 220° C. or less. This is because, when the polymerization solvent and a large amount of water are mixed as described above, a lot of energy is required to separate the two, which is economically disadvantageous.

In the third dilution step (S500), the granular poly phenylene sulfide obtained in step (b) is reslurried in an organic polar solvent one or more times, filtered, and the filtrate is mixed with the first filtrate. , Performing the steps (b) to (d) is an effective means for obtaining a higher purity poly phenylene sulfide (Poly Phenylene Sulfide). At this time, for example, in the case of slurrying twice, a method of filtering the second slurrying liquid and then using the filtrate for the first slurrying is an effective method to reduce the amount of organic polar solvent used.

Slurrying and filtering the poly phenylene sulfide oligomer obtained by step (d) one or more times with water at least once is an effective method for obtaining a higher purity poly phenylene sulfide (Poly Phenylene Sulfide). At this time, for example, in the case of slurrying twice, the method of filtering the second slurrying liquid and then using the filtrate for the first slurrying is an effective method to reduce the amount of water used.

The poly phenylene sulfide thus obtained can be used as it is or dried for various purposes.

It is possible to use it as a recycled raw material of poly phenylene sulfide obtained by the method of the present invention.

FIG. 2 is a flow chart showing a third dilution step of FIG. 1 (a subsequent process for the filtrate of S5000).

As shown, poly phenylene sulfide (Poly Phenylene Sulfide) is separated by the filtrate of the third dilution step (S500), the acidity adjustment step (S510), the fourth filtration step (S520), the fourth dilution step (S530) , It can be obtained through further processing including a fifth filtration step (S540), a sixth dilution step (S550).

[Addition of Acid in Poly Phenylene Sulfide Separation and Recovery Process]

In the acidity adjusting step (S510), the addition of acid in the poly phenylene sulfide oligomer separation and recovery process is necessary to improve recovery efficiency. By adding an acid, the rate of separation of poly phenylene sulfide will significantly improve and lead to an improvement in separation efficiency. In the present invention, it is preferable to add an acid to the recovery slurry (C) and/or the water slurry (D) among the separation and recovery processes. The type of acid used here is not particularly limited, but specific examples include organic acids such as formic acid, acetic acid, propionic acid, butyric acid, chloroacetic acid, dichloroacetic acid, acrylic acid, crotonic acid, benzoic acid, salicylic acid, oxalic acid, malonic acid, succinic acid, phthalic acid and fumaric acid. Acidic compounds, inorganic acidic compounds such as sulfuric acid, phosphoric acid, hydrochloric acid, carbonic acid, and silicic acid can be exemplified, and are preferably organic acidic compounds. Although there is no particular limitation on the amount of acid to be added, the pH of the slurry to which the acid is added is preferably 3 to 8, and more preferably 4 to 7 from the viewpoint of using an appropriate amount of acid. If the filtration rate improvement effect is too high and the pH is too weak and too low, it is not possible to expect a filtration rate improvement effect above a certain level, and there is a possibility of promoting the economic disadvantage or corrosion of the device due to the increase in the use amount.

In the step (d) of the fourth filtration step (S520), if an acid is added to the water slurry (D), not only the acid from the beginning, but preferably a method of filtering twice or more, or first, no acid is added to the water slurry (D) After centrifugation, it is also possible to adopt a method of decanting and then adding the obtained solid water and acid to form a water slurry (D) again, filtering and the like. In particular, the latter method is one of the preferred methods in that it can reduce the amount of acid used.

It is one of the preferred methods that the slurry (A) or the diluted slurry (B) is not added with more than 1 kg of water per 1 kg of dry poly phenylene sulfide resin at a temperature of 220° C. or less. The reason is that mixing the polymerization solvent and water as described above requires a lot of energy to separate the two materials, and is economically disadvantageous.

In the fourth dilution step (S530), the polyphenylene sulfide in the form of granules obtained in step (b) is re-slurried with an organic polar solvent one or more times, and the slurry is filtered in the fifth filtration step (S540). And filtering the filtrate with the filtrate for the first time to perform the above steps (b) to (d) is an effective means to obtain a higher purity poly phenylene sulfide (Poly Phenylene Sulfide). At this time, for example, in the case of slurrying twice, the method of filtering the second slurrying liquid and then using the filtrate for primary slurrying is an effective method in terms of reducing the amount of organic polar solvent used.

In the sixth dilution step (S550), the poly phenylene sulfide (Poly Phenylene Sulfide) oligomer obtained in step (d) is water-slurryed once or more, and the slurry in the sixth filtration step (S560) is more highly purified poly This is an effective method for obtaining phenylene sulfide (Poly Phenylene Sulfide). At this time, for example, in the case of slurrying twice, the method of filtering the second slurrying liquid and using the filtrate for primary slurrying is an effective method in terms of reducing the amount of water used.

Hereinafter, the present invention will be described in more detail by examples, but the scope of the present invention is not limited by examples.

[Example 1]

Diluted slurry (B) was obtained by diluting 10,000 g of the waste mixture slurry (A) with 6,000 g of N-methyl-2-pyrrolidone. 200 g of the slurry (B) heated to 70° C. was filtered with (80 mesh, filtration interval of 0.175 mm) to obtain 150 g of poly phenylene sulfide and recovered slurry (C). The filtration time was 9 minutes. The recovered slurry (C) was taught on a rotating evaporator, treated at 160°C under reduced pressure for 1 hour, and then treated at 160°C for 1 hour in a vacuum dryer. The amount of N-methyl-2-pyrrolidone (N-Methyl-2-pyrrolidone) in the obtained solid was 3% by weight.

The solid was stirred at 70° C. for 30 minutes according to 180 g of ion-exchange water and 1.2 times the recovered slurry (C), and re-slurryed. This slurry was suction-filtered with a glass filter having a filtration area of 9.6 cm 2 (filtration interval 10 to 16 μm) to obtain poly phenylene sulfide. The time required for filtration was 5 minutes. The salt concentration in the filtrate was 10.1%.

[Example 2]

10,000 g of the waste mixture slurry (A) was diluted with 6,000 g of N-methyl-2-pyrrolidone to obtain a diluted slurry (B). 200 g of the dilution slurry (B) heated to 70° C. was filtered with (80 mesh, filtration interval of 0.175 mm) to obtain 150 g of poly phenylene sulfide and recovered slurry (C). The recovered slurry (C) was taught on a rotating evaporator, treated at 160°C under reduced pressure for 1 hour, and then treated at 160°C for 1 hour in a vacuum dryer. The amount of N-methyl-2-pyrrolidone (N-Methyl-2-pyrrolidone) in the obtained solid was 3% by weight.

The solid was stirred for 30 minutes at 70° C. according to the amount of ion-exchange water (180 g of ion-exchange water) (1.2 times of the recovery slurry (C)) and reslurried. Filtration through a glass filter of) to obtain poly phenylene sulfide, and 180 g of ion-exchange water (recovery slurry (C)) was again added to the obtained poly phenylene sulfide. After stirring for 30 minutes at 70° C. and re-slurrying, the slurry was suction-filtered with a glass filter having a filtration area of 9.6 cm 2 (10 to 16 μm in snow gap), and poly phenylene sulfide (Poly Phenylene Sulfide) was filtered. The time required for filtration was 6 minutes, and the saline concentration in the filtrate was 0.1%.

[Example 3]

Diluted slurry (B) was obtained by diluting the waste mixture slurry ((A) with 10,000 g of 6,000 g of N-methyl-2-pyrrolidone). B) 200 g was aged (80 mesh, filtration interval 0.175 mm) to obtain poly phenylene sulfide and 150 g of recovery slurry (C), the filtration time was 9 minutes, and recovery slurry (C) Was taught on a rotating evaporator, treated under reduced pressure at 160° C. for 1 hour, and then treated with a vacuum dryer at 160° C. for 1 hour, N-methyl-2-pyrrolidone (N-Methyl-2) in the obtained solid. The amount of -pyrrolidone) was 3% by weight.

The solid was stirred for 30 minutes at 70°C along with 100 g of ion-exchange water (0.5 times the recovery slurry (C)), and re-slurryed. The slurry was suction filtered through a glass filter having a filtration area of 9.6 cm 2 (filtration interval 10 to 16 μm) to obtain polyphenylene sulfide. The time required for filtration was 45 minutes. Moreover, the saline concentration of the filtrate was 19.4%.

On the other hand, the embodiments of the present invention disclosed in the present specification and drawings are merely to provide a specific example in order to easily explain the technical contents of the present invention and help understanding of the present invention, and other modified examples based on the technical idea of the present invention It is obvious to those of ordinary skill in the art to which the present invention pertains.

Claims (5)

Poly phenylene sulfide (Poly Phenylene Sulfide) and organic obtained by heating a mixture containing at least a polyhalogenated aromatic compound, a sulfide agent, and an organic polar solvent to polymerize a poly phenylene sulfide resin to cool to 220° C. or lower It is a method of separating and recovering poly phenylene sulfide in the form of granules from a mixed waste slurry (A) containing a polar solvent, water and a halogenated alkali metal salt,
In the process of separation and recovery, acid is added,
A method of separating and recovering poly phenylene sulfide from the slurry (A)
(a) slurry (A) 0.5 to 10 mol of an organic polar solvent is added to 1 mol of the sulfide agent used for polymerization to form a dilute slurry (B),
(b) Recovering the granulated polyphenylene sulfide from the diluent slurry (B), and at least a recovered slurry containing polyphenylene sulfide and an organic polar solvent, water and a halogenated alkali metal salt Get (C)
(c) removing at least 50% by weight of organic polar solvent from the recovery slurry (C) to obtain a residue,
(d) adding water to the residual water to remove at least the remaining organic polar solvent and halogenated alkali metal salt from the formed water slurry (D),
A recovery method of poly phenylene sulfide (Poly Phenylene Sulfide) characterized by adding an acid to the recovery slurry (C) and / or water slurry (D) in a separate recovery process to obtain a poly phenylene sulfide (Poly Phenylene Sulfide). delete A method for recovering the poly phenylene sulfide according to claim 1, characterized in that the pH of the recovered slurry (C) and/or the water slurry (D) is adjusted to 3 to 8 by adding an acid. The method for recovering the poly phenylene sulfide (Poly Phenylene Sulfide) according to claim 1 or 3 to remove the organic polar solvent by heating in the step (c). The organic polar solvent is N-methyl-2-pyrrolidone (N-Methyl-2-pyrrolidone), the method of recovering the poly phenylene sulfide (Poly Phenylene Sulfide) according to claim 1 or 3.

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