JP6999269B2 - Method for producing polyarylene sulfide - Google Patents

Description

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

Polyphenylene sulfide (hereinafter, also referred to as "PAS") represented by polyphenylene sulfide (hereinafter, also referred to as "PPS") has heat resistance, chemical resistance, flame retardancy, mechanical strength, electrical characteristics, and dimensional stability. It is an excellent engineering plastic. Since PAS can be molded into various molded products, films, sheets, fibers, etc. by general melt processing methods such as extrusion molding, injection molding, and compression molding, it can be used for electrical equipment, electronic equipment, automobile equipment, packaging materials, etc. It is widely used in a wide range of technical fields.

Alkali metal halides (eg, NaCl) produced as a by-product during the production of PAS are disposed of as wastewater (eg, Patent Document 1).

JP-A-2015-218214

In Patent Document 1, since the wastewater contains an alkali metal halide and a sulfidizing agent (sulfur source) and other organic substances as unreacted raw materials, it is difficult to dispose of the wastewater as it is, and the wastewater. A COD gradual reduction process or the like is required, and therefore an extremely large-scale and complicated process is required.

The present invention has been made in view of the above-mentioned problems, and is obtained from a solid substance containing an alkali metal halide produced as a by-product and an unreacted sulfur source without subjecting a large-scale process to the above-mentioned sulfur. It is an object of the present invention to provide a method for producing PAS capable of recovering the solid substance having a reduced amount of the source and the sulfur source.

As disclosed in the attached drawings, the present inventors have found a new finding that a large amount of sulfur source is present on the surface of an alkali metal halide produced as a by-product, and (1) a protonic organic solvent. Or (2) it was found that the above-mentioned problems can be solved by extracting at least a part of the above-mentioned sulfur source from the above-mentioned solid matter using an extraction solvent which is a mixed solvent containing water and an organic solvent. The present invention has been completed.

The method for producing PAS according to the present invention includes a polymerization step of polymerizing a sulfur source and a dihaloaromatic compound in an organic polar solvent to generate PAS.
An extraction step in which an extraction solvent is brought into contact with a solid containing an alkali metal halide and the sulfur source, which is produced in the polymerization step, and at least a part of the sulfur source is extracted from the solid.
A recovery step in which the solid matter from which at least a part of the sulfur source has been extracted in the extraction step and the extraction liquid produced in the extraction step and containing the extraction solvent and the sulfur source are separated from each other and recovered. When,
Including
The extraction solvent is (1) a protonic organic solvent or (2) a mixed solvent containing water and an organic solvent.
The amount of the sulfur source in the solid matter recovered in the recovery step is 2 parts by mass or less with respect to 100 parts by mass of the alkali metal halide.

In the method for producing PAS according to the present invention, the organic polar solvent is preferably an organic amide solvent.

In the method for producing PAS according to the present invention, the sulfur source is preferably at least one selected from the group consisting of alkali metal sulfide, alkali metal hydrosulfide, and hydrogen sulfide.

In the method for producing PAS according to the present invention, the amount of water in the mixed solvent is preferably 1 part by mass or more and less than 100 parts by mass with respect to 100 parts by mass of the organic solvent.

In the method for producing PAS according to the present invention, the organic solvent in the mixed solvent is preferably an organic polar solvent.

In the method for producing PAS according to the present invention, the temperature in the extraction step and the recovery step is preferably 100 ° C. or higher.

In the method for producing PAS according to the present invention, it is preferable to use at least a part of the extract as at least a part of a raw material for producing PAS in the polymerization step.

According to the present invention, the amount of the sulfur source is reduced from the solid containing the alkali metal halide produced as a by-product and the unreacted sulfur source without performing a large-scale process. And the above-mentioned sulfur source can be recovered, and a method for producing PAS can be provided.

FIG. 1 is a photograph showing the results of SEM (scanning electron microscope) observations performed on a solid substance containing an alkali metal halide produced as a by-product during the production of PAS and an unreacted sulfur source. be. FIG. 2 is a photograph showing the result of element mapping by SEM / EDX (scanning electron microscope / energy dispersive X-ray spectroscopy) performed on the same solid substance as in FIG.

<Manufacturing method of PAS>
The method for producing PAS according to the present invention includes a polymerization step of polymerizing a sulfur source and a dihaloaromatic compound in an organic polar solvent to generate PAS.
An extraction step in which an extraction solvent is brought into contact with a solid containing an alkali metal halide and the sulfur source, which is produced in the polymerization step, and at least a part of the sulfur source is extracted from the solid.
A recovery step in which the solid matter from which at least a part of the sulfur source has been extracted in the extraction step and the extraction liquid produced in the extraction step and containing the extraction solvent and the sulfur source are separated from each other and recovered. When,
Including
The extraction solvent is (1) a protonic organic solvent or (2) a mixed solvent containing water and an organic solvent.
The amount of the sulfur source in the solid matter recovered in the recovery step is 2 parts by mass or less with respect to 100 parts by mass of the alkali metal halide. According to the method for producing PAS according to the present invention, it is possible to efficiently extract the sulfur source from the solid while suppressing the dissolution of the alkali metal halide from the solid. The sulfur source in the solid matter is derived from the sulfur source charged for the polymerization reaction in the polymerization step, and refers to an unreacted sulfur source.

[Polymerization process]
In the polymerization step, the sulfur source and the dihaloaromatic compound are polymerized in an organic polar solvent to generate PAS. As the organic polar solvent, the sulfur source, and the dihaloaromatic compound, those usually used in the production of PAS can be used.

Examples of the organic polar solvent include an organic amide solvent; an aprotic organic polar solvent composed of an organic sulfur compound; and an aprotic organic polar solvent composed of a cyclic organic phosphorus compound. Examples of the organic amide solvent include amide compounds such as N, N-dimethylformamide and N, N-dimethylacetamide; N-alkylcaprolactam compounds such as N-methyl-ε-caprolactam; and N-methyl-2-pyrrolidone (hereinafter, "" NMP ”), N-alkylpyrrolidone compounds such as N-cyclohexyl-2-pyrrolidone or N-cycloalkylpyrrolidone compounds; N, N-dialkylimidazolidinones such as 1,3-dialkyl-2-imidazolidinone. Compounds; Tetraalkylurea compounds such as tetramethylurea; Hexaalkylphosphoric acid triamide compounds such as hexamethylphosphoric acid triamide, and the like can be mentioned. Examples of the aprotic organic polar solvent composed of an organic sulfur compound include dimethyl sulfoxide and diphenyl sulfone. Examples of the aprotic organic polar solvent composed of a cyclic organic phosphorus compound include 1-methyl-1-oxophosphoran. Among them, an organic amide solvent is preferable in terms of availability, handleability, etc., and N-alkylpyrrolidone compound, N-cycloalkylpyrrolidone compound, N-alkylcaprolactum compound, and N, N-dialkylimidazolidinone compound are more preferable. , NMP, N-methyl-ε-caprolactum, and 1,3-dialkyl-2-imidazolidinone are even more preferred, with NMP being particularly preferred. The amount of the organic polar solvent used is preferably 1 to 30 mol, more preferably 2 to 15 mol, relative to 1 mol of the sulfur source, from the viewpoint of efficiency of the polymerization reaction and the like.

Examples of the sulfur source include alkali metal sulfide, alkali metal hydrosulfide, and hydrogen sulfide, and alkali metal sulfide and alkali metal hydrosulfide are preferable. The sulfur source can be handled, for example, in the state of an aqueous slurry or an aqueous solution, and is preferably in the state of an aqueous solution from the viewpoint of handleability such as measurable property and transportability. Examples of the alkali metal sulfide include lithium sulfide, sodium sulfide, potassium sulfide, rubidium sulfide, and cesium sulfide. Examples of the alkali metal hydrosulfide include lithium hydrosulfide, sodium hydrosulfide, potassium hydrosulfide, rubidium hydrosulfide, and cesium hydrosulfide.

Examples of the dihaloaromatic compound include o-dihalobenzene, m-dihalobenzene, p-dihalobenzene, dihalotoluene, dihalonaphthalene, methoxy-dihalobenzene, dihalobiphenyl, dihalobenzoic acid, dihalodiphenyl ether, dihalodiphenyl sulfone, and dihalodiphenyl sulfoxide. , Dihalodiphenylketone and the like, the halogen atom refers to each atom of fluorine, chlorine, bromine and iodine, and the two halogen atoms in the dihaloaromatic compound may be the same or different. Among them, p-dichlorobenzene, m-dichlorobenzene, and a mixture thereof are preferable, p-dichlorobenzene is more preferable, and p-dichlorobenzene (hereinafter, also referred to as "pDCB") is preferable in terms of availability, reactivity, and the like. Especially preferable. The amount of the dihalo aromatic compound used is preferably 0.90 to 1.50 mol, more preferably 0.92 to 1.10 mol, still more preferably, with respect to 1 mol of the charged amount of the sulfur source. It is 0.95 to 1.05 mol. When the amount used is within the above range, a decomposition reaction is unlikely to occur, a stable polymerization reaction can be easily carried out, and a high molecular weight polymer can be easily produced.

Each of the organic polar solvent, the sulfur source, and the dihaloaromatic compound may be used alone, or may be used in combination of two or more as long as it is possible to produce PAS.

In the polymerization reaction, a mixture containing the sulfur source and the dihalo aromatic compound is heated to initiate the polymerization reaction, and the melt viscosity measured at a temperature of 310 ° C. and a shear rate of 1,216 sec-1 is 0.1 Pa · s or more. It is a polymerization reaction that produces the polymer of. In order to obtain PAS with higher viscosity, it can be divided into two or more steps. The polymerization reaction is preferably, for example, a pre-polymerization reaction between the sulfur source and the dihalo aromatic compound. The first-stage polymerization reaction is a polymerization reaction in which a mixture containing the sulfur source and the dihalo aromatic compound is heated to initiate the polymerization reaction to produce a prepolymer having a conversion rate of the dihalo aromatic compound of 50% or more.

In the polymerization reaction, it is preferable to carry out the polymerization reaction under heating at a temperature of 170 to 300 ° C. from the viewpoint of the efficiency of the polymerization reaction and the like. The polymerization temperature in the polymerization reaction is more preferably in the range of 180 to 280 ° C. in order to suppress side reactions and decomposition reactions. In particular, in the pre-polymerization reaction, from the viewpoint of the efficiency of the polymerization reaction, the polymerization reaction can be started under heating at a temperature of 170 to 270 ° C. to produce a prepolymer having a conversion rate of a dihaloaromatic compound of 50% or more. preferable. It is more preferable to select the polymerization temperature in the pre-stage polymerization reaction from the range of 180 to 265 ° C. in order to suppress side reactions and decomposition reactions.

The conversion of the dihalo aromatic compound is preferably 50 to 98%, more preferably 60 to 97%, still more preferably 65 to 96%, and particularly preferably 70 to 95%. The conversion rate of the dihalo aromatic compound is calculated by determining the amount of the dihalo aromatic compound remaining in the reaction mixture by gas chromatography and based on the residual amount, the amount of the dihalo aromatic compound charged and the amount of the sulfur source charged. Can be done.

[Extraction process and recovery process]
In the extraction step, the extraction solvent is brought into contact with the solid substance produced in the polymerization step and containing the alkali metal halide and the sulfur source, and at least a part of the sulfur source is extracted from the solid substance. Here, the solubility of the sulfur source in the extraction solvent is large enough to remove the sulfur source from the solid substance, and the extraction solvent is the alkali metal halogen contained in the solid substance. Does not dissolve most of the compound. The ratio represented by (solubility of the sulfur source in the extraction solvent) / (solubility of the alkali metal halide in the extraction solvent) is preferably 0.02 or more, and preferably 0.1 or more. It is more preferably 0.3 or more, and even more preferably 0.3 or more. When the ratio is within the above range, the sulfur source can be extracted from the solid matter more efficiently, and the solid matter having a further reduced amount of the sulfur source can be recovered more easily. The upper limit of the above ratio is not particularly limited, and may be, for example, 1000 or less, or 100 or less. In the alkali metal halide in the solid matter, the alkali metal is not particularly limited, and examples thereof include sodium and potassium, and the halogen is not particularly limited, and examples thereof include fluorine, chlorine, and iodine. Can be mentioned. Each of the alkali metal and the halogen may be used alone or in combination of two or more.

In the recovery step, the solid matter from which at least a part of the sulfur source was extracted in the extraction step and the extract liquid produced in the upper extraction step and containing the extraction solvent and the sulfur source are separated from each other. to recover.

As the extraction solvent, the solubility of the sulfur source in the extraction solvent is large enough to remove the sulfur source from the solid substance, and the extraction solvent is contained in the solid substance. Unless it dissolves most of the alkali metal halides, it is not particularly limited, and for example, a protonic organic solvent is used (more specifically, only a protonic organic solvent is used), or water and an organic solvent are used. A mixed solvent containing the above is used. Each of the above-mentioned extraction solvent, the above-mentioned protonic organic solvent, and the above-mentioned organic solvent may be used alone or in combination of two or more. Above all, the mixed solvent is preferable because the sulfur source can be extracted more efficiently. Since the sulfur source can be extracted more efficiently, the amount of water in the mixed solvent is preferably 1 part by mass or more and less than 100 parts by mass with respect to 100 parts by mass of the organic solvent. It is more preferably 7 parts by mass or more and 75 parts by mass or less, and even more preferably 3 parts by mass or more and 50 parts by mass or less.

Examples of the protonic organic solvent include alcohols, amines, carboxylic acids, sulfonic acids and the like.

As the organic solvent in the mixed solvent, an organic polar solvent is preferable, and an organic amide solvent is more preferable, in consideration of the efficiency of extraction of the sulfur source and the reuse of the extracted sulfur source in the polymerization step. Examples of the organic polar solvent and the organic amide solvent include those exemplified above, and NMP is preferable from the viewpoint of the efficiency of extraction of the sulfur source. Each of the organic polar solvent and the organic amide solvent may be used alone or in combination of two or more. Further, as the organic solvent in the mixed solvent, the protonic organic solvent can also be used.

In the extraction step, as a result of extracting at least a part of the sulfur source from the solid, the solid with a reduced amount of the sulfur source can be obtained. Further, in the extraction step, an extract containing the extraction solvent and the sulfur source is produced.

The method for separating and recovering the solid substance and the extract from each other in the recovery step is not particularly limited, and examples thereof include known solid-liquid separation methods, specifically, filtration, sieving, and the like. Centrifugation and the like can be mentioned. Examples of the filtration include filtration using a fiber filter. Examples of the sieving component include sieving components using a screen. Examples of the centrifuge include centrifugation by a centrifuge.

The temperature in the extraction step and the recovery step is preferably 100 ° C. or higher, more preferably 150 ° C. or higher. When the temperature is 100 ° C. or higher, the solubility of the sulfur source in the extraction solvent tends to increase, so that the sulfur source can be extracted from the solid matter more efficiently, and the amount of the sulfur source is further increased. The reduced solid matter can be recovered more easily. The upper limit of the temperature is not particularly limited, and may be 300 ° C. or lower, or 280 ° C. or lower, from the viewpoint of workability and the like.

The amount of the sulfur source in the solid matter recovered in the recovery step is 2 parts by mass or less, preferably 1 part by mass or less, based on 100 parts by mass of the alkali metal halide. When the amount of the sulfur source is within the above range, the alkali metal halide in the solid matter has a higher purity and can be disposed of more easily. The disposal includes, for example, discharging the alkali metal halide in the solid as an aqueous solution, burying the alkali metal halide in the soil in the form of the solid, and the alkali metal halide in the solid. Can be used as a raw material for electrolysis. In particular, when the alkali metal halide in the solid substance is used as a raw material for electrolysis, the dihalo aromatic compound and the sulfur source are produced from the halogen molecules and the alkali metal hydroxide generated by the electrolysis, respectively. It can be used for the production of PAS. That is, since the alkali metal halide, which is a by-product that has been discarded until now, can be reused as a raw material for PAS production, the process cost in PAS production can be reduced.

At least a part of the extract can be used as at least a part of a raw material for producing PAS in the polymerization step. Thereby, the unreacted sulfur source can be reused in the polymerization step.

[Separation process]
The method for producing PAS according to the present invention may include a separation step of separating the solid substance from the reaction mixture after the polymerization step between the polymerization step and the extraction step. By the separation step, for example, the solid matter and at least a part of the produced PAS can be separated. The method for separating the solid matter from the reaction mixture in the separation step is not particularly limited, and examples thereof include the same methods as exemplified in the recovery step. The temperature in the separation step is not particularly limited, and may be, for example, the same as the temperature in the extraction step and the recovery step.

Examples are shown below, and embodiments of the present invention will be described in more detail. Of course, the present invention is not limited to the following examples, and it goes without saying that various aspects are possible for details.

[Composite example]
In a 20 L autoclave, NMP (5,507 g), 62.3 mass% sodium hydrosulfide aqueous solution (2,339 g, 26.0 mol), and 73.5 mass% sodium hydroxide aqueous solution (1,399 g, 25.7 mol). ) Was charged, and the inside of the autoclave was replaced with nitrogen. Then, the contents in the autoclave are gradually heated to 200 ° C. at normal pressure while stirring, water (1124 g), NMP (691 g), and hydrogen sulfide (0.38 mol) are distilled off, and the autoclave is sealed. did. Subsequently, NMP (2,868 g), water (34.7 g), 97.0% by mass sodium hydroxide (15.3 g), and pDCB (3,803 g, 25.9 mol) were charged into the autoclave. At this point, the composition in the autoclave is 300 g of NMP, 1.3 mol of water and 0.05 mol of sodium hydroxide for 1 mol of sodium sulfide produced by the reaction of sodium hydrosulfide and sodium hydroxide. , PDCB was 1.01 mol.
Under sealing, the contents in the autoclave were heated to 180 ° C. with stirring, then heated from 180 ° C. to 260 ° C. for 150 minutes, and then rapidly cooled to obtain a polymerization mixture.

[Example 1]
The polymerization mixture (729 g) obtained in the synthesis example was charged into a 1 L autoclave, the inside of the autoclave was replaced with nitrogen, and then the autoclave was sealed. The contents in the autoclave were heated to 245 ° C. with stirring, immediately pressurized with nitrogen (1 MPa), and filtered through a fiber filter (opening 12 μm). The filtration residue in the autoclave was cooled to about 100 ° C. and the autoclave was opened.
NMP (500 g) and water (63 g) were added to the opened autoclave, the inside of the autoclave was replaced with nitrogen, and then the autoclave was sealed. The contents in the autoclave were heated to 245 ° C. with stirring, immediately pressurized with nitrogen (1 MPa), and filtered through a fiber filter (opening 12 μm). The filtration residue in the autoclave was cooled to about 100 ° C. and the autoclave was opened. After that, the same operation was repeated once again.
The obtained filtration residue was dried at 90 ° C. under vacuum to obtain a white powder containing a by-product salt. The amount of sodium sulfide in the white powder was 0.24% by mass. The results are shown in Table 1.

[Example 2]
A white powder containing a by-product salt was obtained in the same manner as in Example 1 except that the amount of water charged into the opened autoclave was changed from 63 g to 18 g. The amount of sodium sulfide in the white powder was 0.96% by mass. The results are shown in Table 1.

[Comparison example]
A white powder containing a by-product salt was obtained in the same manner as in Example 1 except that water was not poured into the open autoclave and extraction was performed only by NMP. The amount of sodium sulfide in the white powder was 2.11% by mass. The results are shown in Table 1.

[Example 3 (reference example) ]
The white powder obtained in the comparative example was observed by SEM (scanning electron microscope) and elemental mapping by SEM / EDX (scanning electron microscope / energy dispersive X-ray spectroscopy). FIG. 1 shows the results of SEM observation, and FIG. 2 shows the results of element mapping by SEM / EDX.

As shown by circled in FIG. 2, it is observed that chlorine (Cl) is not present in the portion where sulfur (S) is present. Since sodium (Na) is present in the same portion, the white powder is mostly composed of sodium chloride, and sulfur content is present as sodium sulfide and / or sodium hydrosulfide on a part of the surface. Is suggested.

From the above observations, in the present invention, the unreacted sulfur source present on the surface of the solid matter containing the alkali metal halide produced as a by-product during the production of PAS is selectively selected by the above extraction solvent. It is presumed that the solid matter with a reduced amount of the sulfur source can be obtained by extraction.

Claims (5)

A polymerization step of polymerizing a sulfur source and a dihaloaromatic compound in an organic polar solvent to produce polyarylene sulfide,
An extraction step in which an extraction solvent is brought into contact with a solid containing an alkali metal halide and the sulfur source, which is produced in the polymerization step, and at least a part of the sulfur source is extracted from the solid.
A recovery step in which the solid matter from which at least a part of the sulfur source has been extracted in the extraction step and the extraction liquid produced in the extraction step and containing the extraction solvent and the sulfur source are separated from each other and recovered. When,
Including
The extraction solvent is a mixed solvent containing water and an organic solvent.
The amount of the sulfur source in the solid matter recovered in the recovery step is 2 parts by mass or less with respect to 100 parts by mass of the alkali metal halide .
The amount of water in the mixed solvent is 2 parts by mass or more and 75 parts by mass or less with respect to 100 parts by mass of the organic solvent.
A method for producing polyarylene sulfide , wherein the organic solvent in the mixed solvent is an organic amide solvent . The method according to claim 1, wherein the organic polar solvent is an organic amide solvent. The method according to claim 1 or 2, wherein the sulfur source is at least one selected from the group consisting of alkali metal sulfide, alkali metal hydrosulfide, and hydrogen sulfide. The method according to any one of claims 1 to 3 , wherein the temperature in the extraction step and the recovery step is 100 ° C. or higher. The method according to any one of claims 1 to 4 , wherein at least a part of the extract is used as at least a part of a raw material for producing polyarylene sulfide in the polymerization step.

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