WO2020080898A1 - Method for separating and refining polyarylene sulfide - Google Patents

Abstract

The present invention provides a method for more efficiently separating and refining polyarylene sulfide following polymerization, the polyarylene sulfide having excellent strength, heat resistance, flame retardancy, and processability when processed into a molded product.

Description

Method for separation and purification of polyarylene sulfide

Mutual citations with related applications

This application claims the benefit of priority based on Korean Patent Application No. 10-2018-0125505 of October 19, 2018 and Korean Patent Application No. 10-2019-0129387 of October 17, 2019, All content disclosed in the literature is incorporated as part of this specification.

The present invention relates to a method for more efficiently separating and purifying polyarylene sulfide having excellent strength, heat resistance, flame retardancy, and processability during processing into a molded article.

Polyarylene sulfide (PAS), typified by polyphenylene sulfide (PPS), is used in metals, especially aluminum or zinc, in automobiles, electrical and electronic products, machinery, etc. due to its excellent strength, heat resistance, flame retardancy, and processability. It is widely used as a material to replace the same die casting metal. Particularly, in the case of PPS resin, since it has good fluidity, it is advantageous to use it as a compound by kneading with a filler or reinforcing agent such as glass fiber.

In general, PAS is widely known as a method for producing a sulfur source and a dihalogenated aromatic compound in a polymerization condition in the presence of an amide compound such as N-methyl pyrrolidone (NMP). Since the polymerization reaction in this production method is a desalting polycondensation mechanism, a large amount of by-products such as sodium chloride are produced. Therefore, after the polymerization reaction, a by-product removal process is required, but by-products are difficult to completely remove by-products, and commercially available PPS products contain thousands of ppm of alkali metal content. In this way, if an alkali metal salt remains in the resulting polymer, problems such as lowering of physical properties such as electrical properties occur. Therefore, if a molded article using such a PAS as a raw material is to be applied to the field of electrical and electronic components, the degradation of electrical properties due to the alkali metal in the PAS becomes a major obstacle.

Accordingly, various methods have been known until now as a method of removing by-products such as sodium chloride from the PAS component. For example, in Japanese Laid-Open Publication No. 1986-220446, reactants containing PPS obtained by reacting sodium sulfide, sodium hydroxide and p-dichlorobenzene in N-methyl-2-pyrrolidone are repeatedly washed with water and hot water. Thereafter, a method of repeating washing in ion-exchanged water after washing with an acidic aqueous solution is also described. However, in order to remove the metal compound (by-product) generated in the reaction generation step of the PAS, in a method of removing the metal compound from the PAS by contacting the mixture containing the solid PAS and the metal compound with water and dissolving the metal compound in water, There is a disadvantage that a long-time washing of the means layer using a large amount of water to remove impurities is required, and thus a very large-scale and complicated process is required. In addition, treatment of a large amount of aqueous wastewater generated in the washing process is also necessary, and there is a problem in that the process cost and environmental load are large. On the other hand, as a method of removing by-products such as sodium chloride from these PAS components, recently, a method of filtering and separating the PAS components using a vibrating mesh and passing sodium chloride together with the waste slurry is known, but in this case, sodium chloride fine powder There is a disadvantage in that the separation efficiency decreases after a few filtrations by blocking the mesh holes.

Further, even after polymerizing the PAS, residual unreacted substances are removed by washing with water or an organic solvent such as N-methyl-2-pyrrolidone (NMP) or acetone. Organic solvents such as N-methyl-2-pyrrolidone used in this way are not only expensive, but are known to be the main cause of environmental pollution when discharged as an aqueous solution, and are generally recycled after being recovered and purified. However, organic solvents such as N-methyl-2-pyrrolidone have excellent compatibility with water as they have high organic solubility, so they are infinitely mixed with water, and a large amount of inorganic salts are dissolved, such as effluent from the PAS manufacturing process. Various separation and purification methods have been attempted since it is difficult to distill as it is. However, when water washing is performed to remove by-products such as sodium chloride from the PAS component, the organic solvent used for washing the PAS and water are mixed, which is expensive to recover the organic solvent.

Accordingly, while minimizing energy consumption and washing costs used in the entire process, while increasing the recovery rate of the organic solvent, the development of a process for more efficiently separating and purifying polyarylene sulfide without lowering separation efficiency even when repeatedly applied continuously Is being demanded.

The present invention is to provide a method for more efficiently separating and purifying polyarylene sulfide having excellent strength, heat resistance, flame retardancy, and processability during processing as a molded article.

The present invention is also intended to provide a method for producing polyarylene sulfide comprising a separation and purification process as described above.

According to an embodiment of the present invention, from the mixed solution containing polyarylene sulfide particles, alkali metal halide particles, and organic solvent, the polyarylene sulfide particles are first used by using a decanter centrifuge under 1000 rpm to 2500 rpm conditions. Separating and separating, separating and removing the alkali metal halide particles together with an organic solvent; And drying the separated polyarylene sulfide particles at 100 ° C to 200 ° C before washing with water. A separation and purification method of polyarylene sulfide is provided.

In addition, according to another embodiment of the invention, the alkali metal hydroxide and the alkali metal hydroxide are dehydrated in a mixed solvent of water and an amide compound to perform sulfide of the alkali metal, and water and amide Preparing a sulfur source comprising a mixed solvent of the compound; Adding a dihalogenated aromatic compound and an amide compound to the reactor containing the sulfur source, and polymerizing to synthesize polyarylene sulfide particles together with alkali metal halide particles; Washing the polymerization reaction product including the polyarylene sulfide particles and alkali metal halide particles with an organic solvent; From the mixed solution containing the polyarylene sulfide particles, alkali metal halide particles, and organic solvent, the polyarylene sulfide particles are first precipitated and separated using a decanter-type centrifugal separator under conditions of 1000 rpm to 2500 rpm, followed by separation of the organic Sedimenting and removing the alkali metal halide particles together with a solvent; And drying the separated polyarylene sulfide particles at 100 ° C to 200 ° C before washing with water. A method for producing polyarylene sulfide is provided.

As described above, according to the present invention, the polyarylene sulfide particles are first sedimented and separated according to the particle size difference and the organic solvent through an optimized drying process before washing with water, without deteriorating the separation efficiency due to alkali metal halide particles. There is an excellent effect of efficiently separating and purifying the polyarylene sulfide particles with a high separation efficiency even if it is separated several times in succession. .

1 is a schematic view showing a process for separating and purifying polyarylene sulfide in Example 1 according to an embodiment of the present invention.

FIG. 2 is a schematic view showing a process of sedimenting and separating polyarylene sulfide particles in a decanter centrifuge according to Example 1, followed by sedimentation and removal of alkali metal halide particles.

3 is a schematic view showing a process for separating and purifying the polyarylene sulfide of Comparative Example 1 according to the prior art.

FIG. 4 is a schematic diagram showing a process of filtering and purifying polyarylene sulfide particles in a vibrating mesh according to Comparative Example 1 from the top and removing alkali metal halide particles through the bottom.

In the present invention, terms such as first and second are used to describe various components, and the terms are used only to distinguish one component from another component.

In addition, the terms used in this specification are only used to describe exemplary embodiments, and are not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this specification, the terms "include", "have" or "have" are intended to indicate the presence of implemented features, numbers, steps, elements or combinations thereof, one or more other features or It should be understood that the existence or addition possibilities of numbers, steps, elements, or combinations thereof are not excluded in advance.

The present invention can be applied to various changes and may have various forms, and specific embodiments will be illustrated and described in detail below. However, this is not intended to limit the present invention to a specific disclosure form, and it should be understood that all modifications, equivalents, and substitutes included in the spirit and scope of the present invention are included.

Hereinafter, the present invention will be described in more detail.

The present invention provides a method for efficiently separating and purifying polyarylene sulfide particles from a mixed solution containing polyarylene sulfide particles, alkali metal halide particles, and an organic solvent.

In particular, the present invention can efficiently separate the polyarylene sulfide particles from the obtained waste solution after washing by using the polyarylene sulfide particles generated from the polyarylene sulfide (PAS) manufacturing process as an organic solvent. So, the polyarylene sulfide particles are first settled and separated according to the difference in particle size using a decanter-type centrifuge, and then washed with water without an organic solvent remaining through an optimized drying process before washing with water. It is characterized by increasing the recovery rate of the organic solvent and reducing the recovery cost.

In addition, in the present invention, the polyarylene sulfide particles generated after polymerization are first precipitated and separated according to the difference in particle size with the decanter centrifugal separator, and the alkali metal halide particles are precipitated together with an organic solvent to be removed together with the waste solution. It is possible to separate and collect the polyarylene sulfide particles efficiently without deteriorating the separation efficiency even if they are separated several times in succession.

According to one embodiment of the invention, the separation and purification method of the polyarylene sulfide is a polyarylene sulfide particle and an organic in a decanter centrifugal mixture from a mixture containing polyarylene sulfide particles, alkali metal halide particles, and an organic solvent. After separation of the solvent, the organic solvent is removed through an optimized drying process before washing with water.

Specifically, the method of separating and purifying the polyarylene sulfide is first, using a decanter-type centrifuge under a condition of 1000 rpm to 2500 rpm from a mixed solution containing polyarylene sulfide particles, alkali metal halide particles, and an organic solvent. And separating the polyarylene sulfide particles first by separating them with an organic solvent, followed by sedimenting and removing the alkali metal halide particles.

The method of separating and purifying the polyarylene sulfide uses a decanter centrifuge instead of a conventional vibrating mesh to filter and purify the polyarylene sulfide particles by alkali metal halide particles ( The problem is that the separation efficiency is reduced after several filtrations due to clogging of mesh holes, and the separation efficiency does not decrease even after several separations in succession.

Particularly, by using under the decanter-type centrifugal 1000 rpm to 2500 rpm, the particles do not proceed to segregation due to sedimentation due to differences in specific gravity of commonly known particles, but particles of alkali metal halides such as sodium chloride have high specific gravity. It is characterized by separating and purifying the polyarylene sulfide particles first by sedimentation rate difference due to the size difference.

In this way, a decanter-type centrifuge can be used under 1000 rpm to 2500 rpm so that the difference in sedimentation speed due to the difference in particle size can appear. When the decanter-type centrifugal separator is used at a rotational speed (rpm) higher than 2500 rpm, sedimentation of the alkali metal halide is accelerated to come out like polyarylene sulfide (PAS) and the separation efficiency is lowered. In addition, when the decanter-type centrifugal separator is used under a condition of less than 1000 rpm, sedimentation takes a long time and there is a problem that the amount of waste liquid in the polyarylene sulfide (PAS) increases.

At this time, the decanter-type centrifuge may be used under a temperature condition of room temperature to 180 degrees Celsius, and may be used under a pressure condition of normal pressure to 5 bar. Here, the normal temperature refers to a temperature (normal pressure, ambient temperature) or room temperature (room temperature) under atmospheric pressure conditions from about 20 ℃ to about 28 ℃, or about 22 ℃ to about 26 It can be about ℃. In addition, the normal pressure refers to a separate pressure or normal pressure without atmospheric pressure (normal pressure, atmospheric pressure) may be about 0.95 atm to about 1.1 atm, or about 0.95 bar to about 1.1 bar.

The specific type of the decanter-type centrifuge that can be used in the separation and purification process of polyarylene sulfide according to the present invention is not particularly limited. For example, decanter-type centrifuges are generally commercially available, and these commercially available ones can be used in the present invention.

The decanter centrifugal seperator is a device capable of separating a liquid-liquid or liquid-based mixture by sedimentation, dehydration, or concentration using centrifugal force. However, in general, decanter-type centrifuges are known to segregate and separate particles having a large specific gravity according to specific gravity of the particles, that is, density difference. However, in the present invention, the decanter-type centrifugal separator is driven under the optimized conditions, and sedimentation and separation of polyarylene sulfide particles are first performed according to particle size differences, rather than sedimentation separation due to specific gravity differences, and then the alkali metal halide particles are precipitated and removed. It is characterized by.

In particular, the present invention is intended to efficiently separate polyarylene sulfide particles from polyarylene sulfide particles generated from a polyarylene sulfide (PAS) manufacturing process and waste liquids containing various inorganic salts and impurities. . Accordingly, the mixed solution introduced into the decanter-type centrifugal separator may be a waste solution generated from a synthesis process of polyarylene sulfide or a washing process, or a mixture thereof, and polyarylene sulfide particles, which are products of the polymerization process, and alkali metal as a by-product. Sodium hydroxide (NaOH), sodium sulfide (Na ₂ S), sodium hydrosulfide (NaSH), together with halide particles, organic solvents used for washing, and water ), And p-dichlorobenzene, or the like.

Here, specific examples of the polyarylene sulfide particles include polyphenylene sulfide (PPS).

The polyarylene sulfide particles may have a particle size of 100 micrometers (μm) to 2000 micrometers (μm), or 150 μm to 1800 μm.

As an example, the polyarylene sulfide particle size may be measured using a standard mesh seive of a process standard having various sieve pore sizes such as 100 μm, 40 μm, or 10 μm. The specific conditions for measuring the particle size of the polyarylene sulfide are not particularly limited, for example, after the polyarylene sulfide particles are about 3 hours or more at a relative humidity of 60% to 78% at about 22 ° C to 26 ° C, The particle size may be measured after storage for preferably at least about 6 hours, or at least about 9 hours, more preferably at least 15 hours, and more preferably at least 24 hours.

Further, the polyarylene sulfide particles may have a density of 1 g / cm ³ to 1.5 g / cm ³ , or 1.1 g / cm ³ to 1.45 g / cm ³ .

As an example, the density may be measured by the method of the American Society for Testing and Materials ASTM D 1505.

Meanwhile, specific examples of the alkali metal halide particles generated as a by-product together with polyarylene sulfide particles in a polyarylene sulfide (PAS) manufacturing process include sodium chloride (NaCl) and sodium iodide (NaI). And one or more of these.

The alkali metal halide particles may have a particle size of 5 μm to 30 μm, or 6 μm to 28 μm.

Further, the alkali metal halide particles may have a density of 1.9 g / cm ³ to 3 g / cm ³ , or 2 g / cm ³ to 2.8 g / cm ³ .

Here, the size and density of the alkali metal halide particles can be measured in the same way as the polyarylene sulfide particles.

In addition, the organic solvent contained in the polyarylene sulfide (Polyarylene sulfide, PAS) polyarylene sulfide particles and by-products together with alkali metal halide particles generated from the process is used in the washing process, the organic solvent of the Specific examples include N-methyl-2-pyrrolidone (NMP), acetone, and isopropyl alcohol (IPA), and may be one or more of them.

Meanwhile, according to one embodiment of the present invention, after separating the polyarylene sulfide particles and the organic solvent using a decanter centrifuge as described above, the separated polyarylene sulfide particles are firstly washed with water. The step of removing the organic solvent and the like through a drying process is performed.

In particular, the primary drying process before washing of the polyarylene sulfide particles is performed prior to water washing under conditions of about 100 ° C to about 200 ° C, thereby increasing the recovery rate of the organic solvent by performing water washing without leaving any organic solvent remaining. And reduce the cost of recovery.

The primary drying process is performed at about 100 ° C to about 200 ° C, preferably about 120 ° C to about 190 ° C, or about 135 ° C to about 180 ° C. Particularly, the primary drying process is performed at about 100 ° C. or higher to evaporate the organic solvent used for polymerization or washing, preferably at about 120 ° C. or higher, or at about 135 ° C. or higher. In addition, in order to prevent crosslinking of polyarylene sulfide (PAS) by contact with hot air in the first drying process, it is performed at about 200 ° C or lower, preferably at about 190 ° C or lower, or at about 180 ° C or lower Can be done.

In addition, the primary drying process may be performed under normal pressure or reduced pressure conditions. The normal pressure is as described above, and the reduced pressure refers to a pressure condition below normal pressure. For example, the primary drying process may be performed under pressure conditions of 4x10 ^-14 bar to 1.1 bar, or 4x10 ^-10 bar to 1.1 bar, or 4x10 ^-6 bar to 1.1 bar. In particular, preferably, the evaporation of the organic solvent is more facilitated, and it can be performed under reduced pressure conditions so that crosslinking does not occur.

In the present invention, water washing may be performed in a state in which no organic solvent is left through the primary drying process before washing of the polyarylene sulfide particles as described above, and the residual amount of the organic solvent in the polyarylene sulfide particles obtained after the drying is 0.5. It is characterized by being less than or equal to 0.3% by weight, or less than or equal to 0.1% by weight.

Subsequently, after removing the organic solvent and the like through the above-described primary drying process, the water washing process for the polyarylene sulfide particles may be repeated one or more times or more. In addition, after washing the dried polyarylene sulfide particles with water, a secondary drying process may be further performed to remove solvents such as water. The second drying process may be performed at about 100 ° C to about 200 ° C, or 130 ° C to about 190 ° C, or about 140 ° C to about 180 ° C. In particular, the second drying process may be performed at about 100 ° C or higher, or about 130 ° C or higher, or about 140 ° C or higher to evaporate a solvent such as water after the washing process. In addition, in order to prevent crosslinking of polyarylene sulfide (PAS) by contact with hot air in the second drying process, it is performed at about 200 ° C or less, preferably at about 190 ° C or less, or at about 180 ° C or less Can be done.

In addition, the secondary drying process may be performed under normal pressure or reduced pressure conditions. The normal pressure is as described above, and the reduced pressure refers to a pressure condition below normal pressure. For example, the secondary drying process may be performed under pressure conditions of 4x10 ^-14 bar to 1.1 bar, or 4x10 ^-10 bar to 1.1 bar, or 4x10 ^-6 bar to 1.1 bar. In particular, it can be carried out under reduced pressure conditions to make evaporation of the solvent such as water easier and to avoid crosslinking.

The polyarylene sulfide particles are first sedimented and separated according to the difference in particle size using a decanter-type centrifuge through the separation and purification method of polyarylene sulfide as described above, followed by organic drying through an optimized drying process before washing with water. Water washing may be performed in a state in which no solvent is left, thereby increasing the recovery rate of the organic solvent and significantly reducing the recovery cost.

In particular, the recovery yield of the polyarylene sulfide (PAS) particles separated and purified through the separation and purification process of the present invention is about 90% or more, or about 95% or more, or about 98% or more, and the washing water obtained through the water washing process The residual content of the organic solvent may be about 0.5% by weight or less, or about 0.1% by weight or less, or 0.05% by weight or less.

Meanwhile, according to another embodiment of the present invention, a method for producing polyarylene sulfide including a separation and purification process as described above is provided.

In the method for preparing the polyarylene sulfide, dehydration of an alkali metal hydrosulfide and an alkali metal hydroxide in a mixed solvent of water and an amide compound is performed, followed by sulfide of the alkali metal, and water and amides. Preparing a sulfur source comprising a mixed solvent of the compound (step 1); Adding a dihalogenated aromatic compound and an amide compound to the reactor containing the sulfur source, and polymerizing to synthesize polyarylene sulfide particles together with alkali metal halide particles (step 2); Washing the polymerization reaction product containing the polyarylene sulfide particles and alkali metal halide particles with an organic solvent (step 3); From the mixed solution containing the polyarylene sulfide particles, alkali metal halide particles, and organic solvent, the polyarylene sulfide particles are first precipitated and separated using a decanter-type centrifugal separator under conditions of 1000 rpm to 2500 rpm, followed by separation of the organic Sedimenting and removing the alkali metal halide particles together with a solvent (step 4); And before washing the separated polyarylene sulfide particles with water, 100 It characterized in that it comprises a; drying step (5 steps) from ℃ to 200 ℃.

In the method for preparing the polyarylene sulfide according to another embodiment of the present invention, each step will be described.

The first step described above is a step of preparing a sulfur source.

The sulfur source is prepared by performing dehydration of an alkali metal hydroxide, an alkali metal hydroxide in a mixed solvent of water and an amide compound. Accordingly, the sulfur source may include a mixed solvent of water and an amide compound remaining after the dehydration reaction, together with the sulfide of the alkali metal produced by the reaction of the alkali metal hydroxide and the hydroxide of the alkali metal.

The sulfide of the alkali metal may be determined according to the type of the alkali metal hydrosulfide used in the reaction, and specific examples thereof include lithium sulfide, sodium sulfide, potassium sulfide, rubidium sulfide or cesium sulfide, and any one of them or Mixtures of two or more can be included.

When preparing a sulfur source by reaction of the alkali metal hydroxide and the hydroxide of the alkali metal, specific examples of the alkali metal hydrosulfide include sodium hydrogen sulfide, sodium hydrogen sulfide, potassium hydrogen sulfide, rubidium hydrogen sulfide, or cesium hydrogen sulfide. have. Any one or a mixture of two or more of these may be used, and anhydrides or hydrates of these may also be used.

In addition, specific examples of the alkali metal hydroxide include lithium hydroxide, sodium hydroxide, potassium hydroxide, rubidium hydroxide, or cesium hydroxide, and any one or a mixture of two or more thereof may be used. The hydroxide of the alkali metal may be used in an equivalent ratio of 0.90 to 2.0, more specifically in an equivalent ratio of 1.0 to 1.5, and more specifically in an equivalent ratio of 1.0 to 1.2, per 1 equivalent of the sulfide of the alkali metal.

On the other hand, in the present invention, equivalent weight means molar equivalent weight (eq / mol).

In addition, in the production of a sulfur source by the reaction of the alkali metal hydroxide and the hydroxide of the alkali metal, an organic acid salt of an alkali metal capable of increasing the polymerization degree of polyarylene sulfide in a short time by promoting a polymerization reaction as a polymerization aid is added. Can be. Specifically, the organic acid salt of the alkali metal may be lithium acetate or sodium acetate, and any one or a mixture of two or more of them may be used. The organic acid salt of the alkali metal may be used in an equivalent ratio of 0.01 to 1.0, more specifically 0.01 to 0.8, and even more specifically 0.05 to 0.5 based on 1 equivalent of the hydrosulfide of the alkali metal.

The reaction of the alkali metal hydroxide with the alkali metal hydroxide may be performed in a mixed solvent of water and an amide compound, wherein specific examples of the amide compound are N, N-dimethylformamide or N, N -Amide compounds such as dimethylacetamide; Pyrrolidone compounds such as N-methyl-2-pyrrolidone (NMP) or N-cyclohexyl-2-pyrrolidone; Caprolactam compounds such as N-methyl-ε-caprolactam; Imidazolidinone compounds such as 1,3-dialkyl-2-imidazolidinone; Urea compounds such as tetramethyl urea; Or phosphate amide compounds such as hexamethylphosphate triamide, and any one or a mixture of two or more of them can be used. Among these, the amide-based compound may be more specifically N-methyl-2-pyrrolidone (NMP) when considering reaction efficiency and cosolvent effect as a polymerization solvent during polymerization for polyarylene sulfide production.

In addition, the water may be used in an equivalent ratio of about 1 to 8 with respect to 1 equivalent of the amide compound, more specifically about 1.5 to 5, and even more specifically about 2.5 to 5.

On the other hand, in the first step, a reactant containing an alkali metal hydrosulfide and an alkali metal hydroxide may generate sulfide of an alkali metal through dehydration. At this time, the dehydration reaction is about 130 In the temperature range of ℃ to 205 ℃, it may be performed by stirring at a rate of about 100 rpm to about 500 rpm. More specifically, about 175 It may be performed by stirring at a rate of about 100 rpm to about 300 rpm in the temperature range of ℃ to 200 ℃. At this time, the time of the dehydration reaction may be performed within about 30 minutes to 6 hours, or about 1 hour to 3 hours.

During the dehydration process, a solvent such as water may be removed through distillation, etc., and a part of the amide compound is discharged together with water, and some sulfur contained in the sulfur source reacts with water by heat during the dehydration process. It can be volatilized as a hydrogen sulfide gas.

On the other hand, as a result of the reaction of the alkali metal hydroxide, alkali metal hydroxide and alkali metal salt, the alkali metal sulfide is precipitated as a solid in a mixed solvent of water and an amide compound. Accordingly, when a polyarylene sulfide according to the present invention is used as a sulfur source, when a sulfur source prepared by reacting the above-mentioned alkali metal hydrosulfide with an alkali metal hydroxide is used, the molar ratio of the sulfur source is the alkali metal injected during the reaction. Let the molar ratio of the sulfides of

Subsequently, a dehydration process is performed to remove a solvent such as water in the reaction product containing the sulfide of the alkali metal produced as a result of the above-described reaction. The dehydration process can be performed according to a method well known in the art, the conditions are not greatly limited, and specific process conditions are as described above.

In addition, during the dehydration process, sulfur contained in the sulfur source reacts with water to generate hydrogen sulfide and alkali metal hydroxide, and the hydrogen sulfide produced is volatilized, so that it remains in the system after the dehydration process by hydrogen sulfide volatilized out of the system during the dehydration process. The amount of sulfur in the sulfur source can be reduced. As an example, when using a sulfur source containing alkali metal hydrosulfide as a main component, the amount of sulfur remaining in the system after the dehydration process is equal to a value obtained by subtracting the molar amount of hydrogen sulfide volatilized out of the system from the amount of sulfur in the input sulfur source. . Accordingly, it is necessary to quantify the amount of effective sulfur contained in the sulfur source remaining in the system after the dehydration process from the amount of hydrogen sulfide volatilized out of the system. Specifically, the dehydration process may be performed until water becomes a molar ratio of 1 to 5, more specifically 1.5 to 4, and more specifically 1.75 to 3.5 with respect to 1 mole of effective sulfur. When the amount of moisture in the sulfur source is excessively reduced by the dehydration process, water can be adjusted by adding water prior to the polymerization process.

Accordingly, the sulfur source prepared by the reaction and dehydration of the alkali metal hydroxide and the alkali metal hydroxide may include a mixed solvent of water and an amide compound, together with the alkali metal sulfide, The water may be specifically included in a molar ratio of 1.75 to 3.5 with respect to 1 mole of sulfur contained in the sulfur source. Further, the sulfur source may further include an alkali metal hydroxide produced by the reaction of sulfur and water.

Meanwhile, according to an embodiment of the present invention, the second step is a step of preparing a polyarylene sulfide by polymerizing the sulfur source with a dihalogenated aromatic compound.

The dihalogenated aromatic compound usable for the production of the polyarylene sulfide is a compound in which two hydrogens in the aromatic ring are substituted with halogen atoms, and specific examples include o-dihalobenzene, m-dihalobenzene, and p-dihal Robenzene, dihalotoluene, dihalonaphthalene, dihalobiphenyl, dihalobenzoic acid, dihalodiphenyl ether, dihalodiphenylsulfone, dihalodiphenylsulfoxide or dihalodiphenyl ketone, etc. Mixtures of two or more can be used. In the dihalogenated aromatic compound, the halogen atom may be fluorine, chlorine, bromine or iodine. Among these, p-dichlorobenzene (p-DCB) may be used when considering the effect of reducing reactivity and formation of side reactions when preparing polyarylene sulfide.

The dihalogenated aromatic compound may be added in an amount of about 0.8 to 1.2 based on 1 equivalent of the sulfur source. When it is added within the above-mentioned content range, polyarylene sulfide having excellent physical properties can be prepared without fear of a decrease in the melt viscosity of the polyarylene sulfide produced and an increase in the chlorine content present in the polyarylene sulfide. have. Considering the superiority of the improvement effect according to the sulfur source and the control amount of the dihalogenated aromatic compound, more specifically, the dihalogenated aromatic compound may be added in an equivalent weight of about 0.9 to 1.1.

In addition, before proceeding to the second step, the step of lowering the temperature of the reactor containing the sulfur source to a temperature of about 150 ℃ to 200 ℃ to prevent the vaporization of the dihalogenated aromatic compound may be further included.

In addition, the polymerization reaction of the above-mentioned sulfur source with a dihalogenated aromatic compound is an aprotic polar organic solvent, and can be carried out in a solvent of an amide-based compound that is stable to alkali at high temperatures.

Specific examples of the amide-based compound are as described above, and when considering reaction efficiency among the exemplified compounds, more specifically, the amide-based compound is N-methyl-2-pyrrolidone (NMP) or N-cyclo It may be a pyrrolidone compound such as hexyl-2-pyrrolidone.

Since the amide compound contained in the sulfur source in the first step may act as a cosolvent, the amide compound added in the second step is a molar ratio of water (H ₂ O) to the amide compound present in the polymerization reaction system. It may be added in an amount such that the (molar ratio of water / amide compound) is about 0.85 or more.

In addition, other additives for controlling the polymerization reaction or molecular weight, such as a molecular weight modifier and a crosslinking agent, may be further added in a content within a range that does not degrade the physical properties and production yield of the final polyarylene sulfide.

The polymerization reaction of the sulfur source and the dihalogenated aromatic compound may be performed at about 200 ° C to 300 ° C. Alternatively, it may be performed in multiple steps while changing the temperature within the above-described temperature range. Specifically, after the first polymerization reaction at about 200 ° C or more and less than about 250 ° C, the second polymerization reaction is performed at a temperature higher than the temperature at the time of the first polymerization, specifically, at about 250 ° C to about 300 ° C. Can be.

The polyarylene sulfide produced as a result of the polymerization reaction is generated in a particle form, and alkali metal halide particles are generated as a by-product together with the polyarylene sulfide particles.

The characteristics related to the polyarylene sulfide particles and alkali metal halide particles thus produced are as described above, and detailed description is omitted.

On the other hand, according to an embodiment of the present invention, the third step is a step of washing with an organic solvent to remove impurities such as oligomers generated after polymerization among reaction products produced as a result of the polymerization reaction.

Specific examples of the organic solvent include N-methyl-2-pyrrolidone (NMP), acetone, and isopropyl alcohol (IPA), and may be one or more of them.

The washing process using an organic solvent may be performed according to a method well known in the art, and the conditions are not particularly limited.

On the other hand, according to an embodiment of the present invention, the fourth step is a step of first separating and purifying polyarylene sulfide particles from a reaction product produced as a result of the polymerization reaction.

For separation and purification of the polyarylene sulfide particles, a mixed solution containing the polyarylene sulfide particles, alkali metal halide particles, and amide compounds is introduced into a decanter type centrifuge, and the decanter type centrifuge is 1000 rpm to By operating under 2500 rpm conditions, the polyarylene sulfide particles are first sedimented and then removed by sedimentation of alkali metal halide particles.

In another embodiment of the present invention, features related to the process of sedimenting and separating the polyarylene sulfide particles using a decanter-type centrifuge are as described above, and detailed description is omitted.

Meanwhile, according to one embodiment of the present invention, the fifth step is to separate the polyarylene sulfide particles and the organic solvent using a decanter centrifuge as described above, and then wash the separated polyarylene sulfide particles with water. It is a step of removing the organic solvent and the like through the primary drying process before.

In particular, the primary drying process before washing of the polyarylene sulfide particles is performed prior to water washing at about 100 ° C to about 200 ° C, thereby increasing the recovery rate of the organic solvent by washing the water with no organic solvent remaining. Costs can be reduced.

In another embodiment of the present invention, the features related to the primary drying process before washing the polyarylene sulfide particles with water are as described above, and a detailed description thereof will be omitted.

Thereafter, the separated and purified polyarylene sulfide particles may be selectively further washed, filtered, or dried using water or the like according to a conventional method.

The specific method for manufacturing the polyarylene sulfide may refer to Examples described later. However, the manufacturing method of polyarylene sulfide is not limited to the contents described in the present specification, and the manufacturing method may further employ the steps conventionally employed in the technical field to which the present invention pertains, and The step (s) can be changed by conventionally changeable step (s).

Hereinafter, preferred embodiments are provided to help understanding of the present invention. However, the following examples are only provided to more easily understand the present invention, and the contents of the present invention are not limited thereby.

Example 1

1-1. Preparation of polyphenylene sulfide

Sodium sulfide is prepared by mixing 70% sodium hydrogen sulfide (NaSH) and sodium hydroxide (NaOH) in an equivalent ratio of 1: 1.05 to make a PPS polymer. At this time, 0.4 equivalents of sodium acetate (CH ₃ COONa) powder, 1.65 equivalents of N-methyl-2-pyrrolidone (NMP), and 4.72 equivalents of deionized water (DI water) were added to the reactor. Here, equivalent weight means molar equivalent weight (eq / mol). At this time, the solid reagent was first added and then added in the order of NMP and DI water. Then, the reactor was stirred at about 150 rpm and dehydrated by heating to about 195 ° C. for 1 hour 40 minutes. Then, the temperature of the reactor was lowered to about 175 ° C., and 1.02 times equivalent of para-dichlorobenzene (p-DCB) and 1.35 equivalents of N-methyl-2-pyrrolidone (NMP) of sodium hydrogen sulfide were added to the reactor. Did. Thereafter, the reaction mixture is heated to about 230 degrees Celsius as a shear reaction and reacted for about 2 hours, and then heated to about 255 degrees Celsius as a subsequent reaction to react for about 2 hours, and then about 3 equivalents of distilled water is added and about Stir for 5 minutes. Then, 500 g of a slurry containing the resulting PPS polymer particles was obtained. The slurry contains polyarylene sulfide particles, alkali metal halide particles, and amide compounds.

1-2. Separation and purification of polyphenylene sulfide

100 g of the slurry produced in step 1-1 was collected and washed once using NMP 100 g each, for the obtained mixed solution, a filtration process using a decanter-type centrifuge as shown in FIG. 1 (filtration ) To isolate polyarylene sulfide with a PPS wet cake. At this time, the decanter type centrifuge was used at room temperature and atmospheric pressure at 1000 rpm.

The PPS wet cake thus obtained was subjected to a primary vacuum drying process under a pressure of about 0.15 bar or less at a temperature of 150 ° C. prior to washing the water to produce dry PPS. The residual amount of organic solvent in the dry PPS was 0.5% by weight or less. Subsequently, after repeated washing four times using 50 g of water, a second vacuum drying process was performed under a condition of a pressure of about 0.15 bar or less at 150 ° C.

The time taken to filter 100 g of the generated PPS slurry by repeating the above process was 0.3 hours in total, including additional time such as input, and the total amount of PPS particles separated and purified was about 15.2 g, and remained in the wastewater after recovery. The weight of the portion of the PPS fine powder recovered further using a fine filter was about 0.31 g. Accordingly, it was confirmed that the recovery yield of the separated and purified PPS particles in the total content of the total PPS particles thus recovered was about 98%. In addition, it was confirmed that the NMP content in the washing water collected through the water washing process performed before the last drying step is 500 ppm (0.05% by weight).

Comparative Example 1

In performing the separation and purification process on the obtained mixed solution after performing a one-time washing using NMP 50 g by fractionating 100 g of the slurry produced in step 1-1 of Example 1, as shown in FIG. 3 Instead of a decanter centrifuge, a filtration process is performed under normal temperature and pressure conditions using a vibrating mesh (see FIG. 4) to obtain a PPS wet cake to wash water without a separate primary drying process. A polyarylene sulfide was separated and purified in the same manner as in Example 1, except that the process was performed.

The time required to filter 100 g of the generated PPS slurry by repeating the above process was 0.5 hours, and the total amount of PPS particles separated and purified was about 14.7 g, and the recovery yield was about 94.8%. In addition, the NMP content in the washing water collected through the water washing process performed before the last drying step can be seen that the separation efficiency was significantly reduced to 4% by weight.

Comparative Example 2

In performing the separation and purification process for the obtained mixed solution after performing a one-time wash using NMP 50 g by fractionating 100 g of the slurry produced in step 1-1 of Example 1, instead of vacuum drying, a tray (tray ) Was subjected to a separation and purification process of polyarylene sulfide in the same manner as in Example 1, except that drying was performed at 90 ° C at atmospheric pressure.

The time required to filter 100 g of the generated PPS slurry by repeating the above process was 0.3 hours in total, including additional time such as input, and the total amount of the separated and purified PPS particles was about 15.4 g, and remained in the wastewater after recovery. The weight of the portion of the PPS fine powder recovered further using a fine filter was about 0.11 g. Accordingly, it was confirmed that the recovery yield of the separated and purified PPS particles in the total content of the total PPS particles thus recovered was about 98%. In addition, it can be seen that the separation efficiency was lowered to 4000 ppm (0.4% by weight) in the NMP content of the collected washing water through the water washing process performed before the last drying step.

Claims (13)

1. From the mixed solution containing polyarylene sulfide particles, alkali metal halide particles, and an organic solvent, the polyarylene sulfide particles are first precipitated and separated using a decanter-type centrifugal separator under conditions of 1000 rpm to 2500 rpm, followed by separation of the organic solvent. Sedimenting and removing the alkali metal halide particles with; And

   Drying the separated polyarylene sulfide particles at 100 ° C to 200 ° C before washing with water;

   The separation and purification method of polyarylene sulfide containing.
2. According to claim 1,

   The mixed solution is a waste solution generated in the synthesis process or washing process of polyarylene sulfide,

   Method for separation and purification of polyarylene sulfide.
3. According to claim 1,

   The polyarylene sulfide particles, the particle size is 100 ㎛ to 2000 ㎛,

   Method for separation and purification of polyarylene sulfide.
4. According to claim 1,

   The polyarylene sulfide particles have a density of 1 g / cm ³ to 1.5 g / cm ³ ,

   Method for separation and purification of polyarylene sulfide.
5. According to claim 1,

   The alkali metal halide particles, at least one selected from the group consisting of sodium chloride and sodium iodide,

   Method for separation and purification of polyarylene sulfide.
6. According to claim 1,

   The alkali metal halide particles, the particle size is 5 ㎛ to 30 ㎛,

   Method for separation and purification of polyarylene sulfide.
7. According to claim 1,

   The alkali metal halide particles, the density is 1.9 g / cm ³ to 3 g / cm ³ ,

   Method for separation and purification of polyarylene sulfide.
8. According to claim 1,

   The organic solvent is at least one selected from the group consisting of N-methyl-2-pyrrolidone, acetone, and isopropyl alcohol,

   Method for separation and purification of polyarylene sulfide.
9. According to claim 1,

   The mixed solution further comprises at least one selected from the group consisting of sodium hydroxide, sodium acetate, sodium sulfide, sodium hydrogen sulfide, and p-dichlorobenzene,

   Method for separation and purification of polyarylene sulfide.
10. According to claim 1,

    The step of drying the separated polyarylene sulfide particles is performed under normal pressure or reduced pressure conditions,

    Method for separation and purification of polyarylene sulfide.
11. According to claim 1,

    The polyarylene sulfide particles obtained after the drying step, the organic solvent residual amount is 0.5% by weight or less,

    Method for separation and purification of polyarylene sulfide.
12. According to claim 1,

    After washing the polyarylene sulfide particles obtained after the drying step with water, further comprising drying at 100 ℃ to 200 ℃,

    Method for separation and purification of polyarylene sulfide.
13. Dehydration of an alkali metal hydroxide and an alkali metal hydroxide in a mixed solvent of water and an amide compound is performed to obtain a sulfur source comprising an alkali metal sulfide and a mixed solvent of water and an amide compound. Manufacturing;

    Adding a dihalogenated aromatic compound and an amide compound to the reactor containing the sulfur source, and polymerizing to synthesize polyarylene sulfide particles together with alkali metal halide particles;

    Washing the polymerization reaction product including the polyarylene sulfide particles and alkali metal halide particles with an organic solvent;

    From the mixed solution containing the polyarylene sulfide particles, alkali metal halide particles, and organic solvent, the polyarylene sulfide particles are first precipitated and separated using a decanter-type centrifugal separator under conditions of 1000 rpm to 2500 rpm, followed by separation of the organic Sedimenting and removing the alkali metal halide particles together with a solvent; And

    Drying the separated polyarylene sulfide particles at 100 ° C to 200 ° C before washing with water;

    The method of manufacturing a polyarylene sulfide containing.

Images