KR102499842B1 - Process for preparing polyarylene sulfide - Google Patents

Abstract

According to the present invention, in the dehydration process for providing a sulfur source for producing polyarylene sulfide, the basicity of the dehydration liquid is adjusted to convert hydrogen sulfide discharged from the dehydration liquid into sulfide of an alkali metal, which is a sulfur source, and then convert it into a reaction system. By supplying to, it is possible to prevent loss of sulfur source and reduce the capacity of the scrubber, and at the same time effectively treat hydrogen sulfide, which is harmful to the human body and causes air pollution, to provide an environmentally friendly method for producing polyarylene sulfide with improved yield.

Description

Method for producing polyarylene sulfide {PROCESS FOR PREPARING POLYARYLENE SULFIDE}

The present invention relates to a method for producing polyarylene sulfide capable of reducing hydrogen sulfide emissions.

Polyarylene sulfide (PAS), represented by Polyphenylene sulfide (PPS), is widely used with metals, especially aluminum and zinc, in automobiles, electrical/electronic products, and machinery due to its excellent strength, heat resistance, flame retardancy, and workability. It is widely used as a material to replace the same die casting metal. In particular, since PPS resin has good fluidity, it is advantageous to use it as a compound by kneading it with fillers or reinforcing agents such as glass fibers.

In general, PAS is prepared by polymerization of a sulfur source and a dihalogenated aromatic compound under polymerization conditions in the presence of a polar organic compound such as N-methyl pyrrolidone (NMP), and optionally a molecular weight modifier such as an alkali metal salt may be further used. do. Reaction products obtained as a result of such a polymerization reaction include an aqueous phase and an organic phase, and the produced PAS is mainly dissolved in the organic phase.

At this time, in order to provide the sulfur source, the alkali metal hydrosulfide and alkali metal hydroxide are reacted in a mixed solvent of water and an amide compound. In order to proceed with the forward reaction, dehydration to remove water from the reaction system process proceeds.

However, in the dehydration process, there is a problem in that H2S (hydrogen sulfide gas), a by-product, escapes along with water and organic solvent. Since the hydrogen sulfide gas is harmful to the human body, separate treatment is required during the process, and since it escapes in the gas phase without dissolving in water, a separate scrubber must be constructed to remove it.

However, in order to construct the scrubber, a method for effectively treating hydrogen sulfide gas is required because the cost for equipment equipment increases and the process also becomes long.

An object of the present invention is to adjust the basicity of the dehydration solution itself, including hydrogen sulfide as a by-product, in a dehydration process for providing a sulfur source used in the production of polyarylene sulfide, and then distilling the dehydration solution to obtain hydrogen sulfide as a sulfur source. It is to provide a method for producing polyarylene sulfide capable of preventing loss of sulfur sources and reducing scrubber capacity by converting phosphorus alkali metal sulfides and recycling them to the reaction system.

In the present specification, a dehydration process including a dehydration reaction of an alkali metal hydrosulfide and an alkali metal hydroxide and a treatment step of a reaction by-product is performed in a mixed solvent of water and an amide-based compound to provide a sulfur source including an alkali metal sulfide. doing; and

Preparing polyarylene sulfide by polymerizing the sulfur source, the dihalogenated aromatic compound, and the amide-based compound; Including,

The treatment of the reaction by-products includes forming an alkali metal sulfide by adding an alkali metal hydroxide to a dehydration solution containing hydrogen sulfide generated as a by-product of the dehydration reaction.

A method for producing polyarylene sulfide is provided.

The dehydration step is a dehydration reaction of an alkali metal hydrosulfide and an alkali metal hydroxide in a mixed solvent of water and an amide-based compound, thereby dehydrating the alkali metal sulfide, a mixed solvent of water and an amide-based compound, and hydrogen sulfide as a by-product. A first step of providing a sulfur source while discharging the liquid; and

The discharged dehydration liquid is distilled to separate the amide-based compound in the mixed solvent and refluxed in the first step, and the dehydration liquid including hydrogen sulfide, water, and the amide-based compound not separated in the distillation are distilled by-products of the dehydration liquid The second step of collecting; and

It may be preferable to include; a third step of injecting an alkali metal hydroxide into the collected dehydration solution to adjust the basicity of the dehydration solution, and then distilling the dehydration solution to form an alkali metal sulfide to treat reaction by-products. there is.

The method may further include supplying the sulfide of the alkali metal obtained in the third step to the first step as a sulfur source.

The alkali metal hydroxide is used in an equivalent ratio of 0.9 to 1.5 with respect to 1 equivalent of the alkali metal hydrosulfide, and is divided and introduced at a ratio of 1: 0.1 to 0.3 in the dehydration reaction and hydrogen sulfide treatment step within the equivalent ratio range. can

The alkali metal hydroxide is introduced into the reactor at an equivalent ratio of 0.9 to 1.5 with respect to 1 equivalent of alkali metal hydrosulfide, and in the dehydration reaction, with respect to 1 equivalent of alkali metal hydrosulfide, in an equivalent ratio of 0.8 to 1.2, In the step of treating hydrogen sulfide, it is preferable to use it by introducing it into a storage tank at an equivalent ratio of 0.1 to 0.3 with respect to 1 equivalent of alkali metal hydrosulfide.

In the step of treating hydrogen sulfide, it is preferable to use a sodium hydroxide solution having a concentration of 10 to 50% by weight as the hydroxide of the alkali metal.

In the third step, after the alkali metal hydroxide is added, the pH of the dehydration solution may be 10 to 15.

In the third step, the pH after distillation of the dehydrated liquid may be 7 to 8.5.

The present invention effectively collects the amount of by-product (hydrogen sulfide) generated in the dehydration reaction by directly adjusting the pH by directly adjusting the pH by injecting an alkali metal hydroxide into the dehydration solution after collecting the dehydration solution generated in the dehydration process of polyarylene sulfide. Thus, it can be provided as a sulfur supply source. Therefore, it is possible to minimize the loss of the sulfur supply source compared to the prior art. That is, since the hydrogen sulfide passing through the dehydration solution reacts with the hydroxide of an alkali metal, it is possible to prevent loss of sulfur sources and reduce scrubber capacity. In addition, it is possible to easily provide polyarylene sulfide, which is environmentally friendly, has improved productivity, and has excellent physical properties, by polymerizing the sulfur source obtained by the above method with a dihalogenated aromatic compound.

1 is a schematic diagram of a dehydration process in producing polyarylene sulfide according to an embodiment of the present invention.
2 schematically illustrates a process chart for preparing the polyarylene sulfide of Example 1 according to one embodiment of the present invention.

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

In addition, 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 dictates otherwise. In this specification, terms such as "comprise", "comprise" or "having" are intended to indicate that there is an embodied feature, number, step, component, or combination thereof, but one or more other features or It should be understood that the presence or addition of numbers, steps, components, or combinations thereof is not precluded.

In addition, since the present invention can have various changes and various forms, specific embodiments will be exemplified and described in detail below. However, it should be understood that this is not intended to limit the present invention to the specific disclosed form, and includes all modifications, equivalents, and substitutes included in the spirit and scope of the present invention.

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

According to one embodiment of the present invention, a dehydration process including a dehydration reaction of an alkali metal hydrosulfide and an alkali metal hydroxide and a treatment step of reaction by-products is performed in a mixed solvent of water and an amide-based compound to obtain alkali metal sulfide containing providing a sulfur source; and

Preparing polyarylene sulfide by polymerizing the sulfur source, the dihalogenated aromatic compound, and the amide-based compound; Including,

The treatment of the reaction by-products includes forming an alkali metal sulfide by adding an alkali metal hydroxide to a dehydration solution containing hydrogen sulfide generated as a by-product of the dehydration reaction.

A method for producing polyarylene sulfide may be provided.

In the process of treating the dehydration solution generated in the dehydration reaction for preparing a sulfur source during the production process of polyarylene sulfide, the present invention directly adjusts the pH of the dehydration solution to a neutral to weakly basic range, thereby performing the dehydration reaction. Hydrogen sulfide generated as a by-product of can be easily converted into sulfides of alkali metals.

That is, a dehydration solution is discharged through a dehydration reaction. After the dehydration solution is removed, water, an amide-based compound, and hydrogen sulfide, which is a by-product of the dehydration reaction, are included in the dehydration solution. Accordingly, in the present invention, after directly introducing an alkali metal hydroxide into the dehydration solution, when the dehydration solution is distilled and refluxed, the hydrogen sulfide contained in the dehydration solution reacts with the alkali metal hydroxide, and is converted into an alkali metal sulfide as a sulfur source. can be The alkali metal sulfide converted in this way can be supplied to the reaction system again to supplement the sulfur source. Therefore, since the hydrogen sulfide passing through the dewatering liquid reacts with the hydroxide of an alkali metal, it is possible to prevent a loss of a sulfur source and reduce a scrubber capacity. In addition, it is possible to easily provide polyarylene sulfide, which is environmentally friendly, has improved productivity, and has excellent physical properties, by polymerizing the sulfur source obtained by the above method with a dihalogenated aromatic compound.

Each step is described below.

In the present invention, in order to provide a sulfur source (alkali metal sulfide) in a reactor, an alkali metal hydrosulfide and an alkali metal hydroxide undergo a dehydration reaction in a mixed solvent including water and an amide-based compound.

At this time, collecting the dehydration liquid including hydrogen sulfide and water generated as a by-product during the dehydration reaction into a storage tank; Controlling the basicity of the dehydration solution in the storage tank; and distilling and refluxing the dehydrated liquid.

In the step of adjusting the basicity of the dehydration solution, after directly introducing the alkali metal hydroxide into the storage tank, hydrogen sulfide in the dehydration solution reacts with the alkali metal hydroxide to be converted into an alkali metal sulfide through distillation and reflux. Sulfide can be recycled to the reaction system and supplemented with a sulfur source.

In addition, when the pH of the dehydration solution is adjusted by the above method, the reaction is as shown in Scheme 1 below, so that the initial dehydration solution is neutral to weakly basic, then becomes strongly basic, and then it can be adjusted from strong basicity to neutral to weakly basic. there is.

[Scheme 1]

Therefore, it is possible to minimize the loss of the sulfur source in the dehydration process compared to the prior art. In addition, since the sulfur source thus obtained is provided in a state in which loss is minimized after the dehydration is completed, the yield of polyarylene sulfide can be improved through a polymerization reaction with a dihalogenated aromatic compound.

Specifically, in the present invention, hydrogen sulfide, a by-product of the dehydration reaction, is absorbed into an alkali metal hydroxide to form a sulfur source and used in the reaction solution. At this time, the present invention is characterized in that, after adding an alkali metal hydroxide to the dehydration solution itself, when the dehydration solution is refluxed, an alkali metal sulfide is formed and the pH is adjusted to a neutral to weakly basic range.

In the present invention, a sulfur source is created while the dehydration liquid is removed through the dehydration reaction. Water, amide-based compounds, and hydrogen sulfide as a reaction by-product exist in the removed dehydration solution, and amide-based compounds enter the reaction system and water is removed as much as possible while refluxing (recirculating) is performed to separate the amide-based compounds and water.

At this time, the dehydration liquid removed after the initial dehydration reaction becomes neutral to weakly basic, and since hydrogen sulfide, which is a by-product in the dehydration process, is released into the gas phase and leads to a loss of sulfur sources, it is important to control the pH of the initial dehydration liquid in the storage tank. do.

Therefore, the present invention is characterized in that the sulfur source loss is reduced by adjusting the pH of the initial dehydration liquid.

Therefore, in the present invention, alkali metal hydroxide is added to the removed dehydration solution, and when the pH-adjusted dehydration solution is refluxed in this process, hydrogen sulfide partially dissolved in the dehydration solution is also converted to a sulfur source or in the column/dehydration line. Any hydrogen sulfide present is also converted to a sulfur source. It can be put into the reaction system again like an amide-based compound to reduce loss of a sulfur source. In addition, the alkali metal hydroxide can contribute to efficiently supplying a sulfur source because the previously used amount is divided into the initial dehydration reaction step and the storage tank.

In addition, after the dehydration is completed, a step of preparing polyarylene sulfide by polymerizing a sulfur source, a dihalogenated aromatic compound, and an amide-based compound may be followed.

According to this method, hydrogen sulfide and alkali metal hydroxides react in the column of the distillation column for distilling the dehydrated liquid, so that the water leaves the distillation column as it is and is collected separately in the storage tank, and the sulfur source obtained through the reaction is introduced into the reactor. to be put in

Therefore, in the present invention, since the amount of hydrogen sulfide generated as a by-product is minimized and sent to the inside of the reactor, loss of sulfur source can be reduced. Moreover, the method of the present invention does not require the installation of a scrubber to prevent air pollution caused by hydrogen sulfide escaping as a reaction by-product, and can also reduce the scrubber capacity.

When the amount of hydrogen sulfide that escapes during the dehydration process increases, the loss of internal sulfur sources increases, so hydrogen sulfide reacts with alkali metal hydroxides to form sulfides of alkali metals, which are introduced into the reaction system and water is discharged again. That is, when the amide-based compound is refluxed into the reactor, the sulfide of the alkali metal may be supplied to the reactor together.

In addition, when a large amount of sulfur loss occurs, the monomer equivalence ratio (sulfide and dihalogenated compound) is changed, causing polymerization problems, reducing the yield of the final material and increasing the melting rate.

Preferably, in the dehydration process, the reaction by-product means to include hydrogen sulfide generated as a by-product of the dehydration reaction. In the dehydration process, the step of treating the reaction by-products includes adding an alkali metal hydroxide to a dehydration solution containing hydrogen sulfide generated as a by-product of the dehydration reaction to form an alkali metal sulfide; including, treating hydrogen sulfide may be a step.

For example, in order to treat hydrogen sulfide, which is a reaction by-product in the dehydration process, an alkali metal hydroxide is directly added to the dehydration liquid containing hydrogen sulfide generated as a by-product of the dehydration reaction to adjust the basicity of the dehydration liquid, A step of forming an alkali metal sulfide by distilling the dehydrated liquid through a reaction between the alkali metal hydroxide and hydrogen sulfide may be performed.

More specifically, by dehydrating alkali metal hydrosulfide and alkali metal hydroxide in a mixed solvent of water and amide compound, dehydration solution including alkali metal sulfide, water and amide compound solvent, and by-product hydrogen sulfide A first step of providing a sulfur source while discharging; and

The discharged dehydration liquid is distilled to separate the amide-based compound in the mixed solvent and refluxed in the first step, and the dehydration liquid including hydrogen sulfide, water and the amide-based compound not separated in the distillation as a distillation by-product of the dehydration liquid The second step of collecting; and

A third step of injecting an alkali metal hydroxide into the dehydration solution collected in the second step to adjust the basicity of the dehydration solution, and then distilling the dehydration solution to form an alkali metal sulfide to treat reaction by-products. can include

At this time, the initial pH of the dehydration solution in the second step is neutral to weakly basic. In addition, when alkali metal hydroxide is added in the third step, the dehydration solution becomes strongly basic. And, while the strongly basic dehydration liquid is refluxed through distillation, it reacts with hydrogen sulfide in the dehydration liquid to finally become neutral or weakly basic again.

Therefore, the dehydration solution in the second step means the pH before the alkali metal hydroxide is introduced. In addition, the dehydration solution in the third step may be divided into a pH after the alkali metal hydroxide is added and a pH after distillation of the dehydration solution.

For example, in the third step, after the alkali metal hydroxide is added, the pH may be 10 to 15. In addition, in the third step, the pH of the dehydrated liquid after distillation may be 7 to 8.5. Therefore, the initial pH of the third step is strongly basic, and may become neutral or weakly basic when the reaction of hydrogen sulfide is complete.

In addition, when the dehydration liquid is distilled and refluxed in the third step, an alkali metal hydroxide and hydrogen sulfide contained in the dehydration liquid react to form an alkali metal sulfide.

Thereafter, a step of supplying the sulfide of the alkali metal obtained in the third step to the first step as a sulfur source may be further included. The alkali metal sulfide supplied to the reaction system in the first step is replenished as a sulfur source, thereby contributing to an improvement in the production yield of polyarylene sulfide.

1 is a schematic diagram of a dehydration process in producing polyarylene sulfide according to an embodiment of the present invention.

According to the method of the present invention, dehydration is performed by partially refluxing the dehydration liquid into the distillation column as shown in FIG. 1 to separate water and organic solvent.

At this time, during the dehydration process, about 1 to 3 mol% of H2S compared to the initial input S is released. In the present invention, in order to recover and recycle H2S, an alkali metal hydroxide is directly added to the dehydration liquid and the dehydration liquid is refluxed into the distillation column. Adjust the pH to neutral to slightly basic. Thereafter, the pH of the dehydration liquid in the distillation column is adjusted to a neutral to slightly basic level of 7 to 8.5, and then a reaction between hydrogen sulfide and an alkali metal hydroxide proceeds in the dehydration liquid having a lowered basicity. A sulfide of can be generated and supplied to the reaction system.

Referring to FIG. 1, first, the reactor 1 for performing the dehydration reaction is connected to the lines 2 and 3 of the distillation column 4. When dehydration proceeds, the dehydrated liquid goes up to the distillation column through line (2), and the organic solvent separated by the boiling point of water and organic amide solvent in the distillation column (4) is returned to the reactor (1) through line (3). It is refluxed. At this time, the distillation tower (4) should be designed to efficiently separate water and organic amide solvent. The dehydrated liquid coming out of the distillation tower (4) passes through the condenser (6) and is converted into a liquid phase and stored in the storage tank (7). At this time, the liquefied dehydration solution contains water and some organic amide solvent. Therefore, in order to remove some of the organic amide solvent from the dehydration solution, the dehydration solution in the storage tank 7 is refluxed back to the distillation column 4 using the circulation pump 8 to perform fractional distillation. If this continues, only water (11) remains in the dehydration liquid in the storage tank (7).

However, since the generated hydrogen sulfide 10 is not condensed by cooling and does not dissolve in the dehydration liquid, it exists in the storage tank 7 as a gaseous state. Therefore, in the present invention, the alkali metal hydroxide (9) is added to the storage tank (7), but it is added by dividing it into small amounts among the amount used in the entire dehydration process. According to this method, the pH of the dehydrated liquid can be adjusted as described above, and the pH-adjusted dehydrated liquid is refluxed to the distillation column 4 using the circulation pump 8. In the distillation tower (4), hydrogen sulfide is adsorbed in the distillation tower (4) by the alkali metal hydroxide contained in the refluxed dehydration liquid and converted into an alkali metal sulfide. The sulfide of the alkali metal is refluxed to the reactor 1 through the line 3 to reduce the loss of the sulfur source, thereby improving the yield of polyarylene sulfide.

Conditions for distillation and reflux of the dehydrated liquid in the distillation column are not particularly limited, and may be performed according to a method well known in the art.

Meanwhile, the alkali metal hydroxide may be used by dividing the content used during the entire dehydration reaction. For example, the content to be initially dehydrated and the content to be added to the dehydration liquid may be divided at a predetermined ratio and used in the process.

For example, the alkali metal hydroxide is used in an equivalent ratio of 0.9 to 1.5 with respect to 1 equivalent of the alkali metal hydrosulfide, and in the dehydration reaction and reaction by-product treatment step within the equivalent ratio range, in a ratio of 1: 0.1 to 0.3. It can be divided into inputs.

At this time, if the content of the alkali metal hydroxide added to the dehydration solution exceeds the above ratio, the molar ratio of the alkali metal hydroxide to the sulfur source increases, which may increase the deterioration of the organic amide solvent or cause side reactions during polymerization. In addition, if the content of the alkali metal hydroxide introduced into the dehydration solution is too small, there is a possibility that hydrogen sulfide collection may not be performed properly.

According to a preferred embodiment, the alkali metal hydroxide is in an equivalent ratio of 0.9 to 1.5 with respect to 1 equivalent of alkali metal hydrosulfide, and in the dehydration reaction, in an equivalent ratio of 0.8 to 1.2 with respect to 1 equivalent of alkali metal hydrosulfide. In the step of treating the reaction by-products, it is preferable to use them by introducing them into a storage tank at an equivalent ratio of 0.1 to 0.3 to 1 equivalent of alkali metal hydrosulfide.

More preferably, during the dehydration reaction, the alkali metal hydroxide may be used in an equivalent ratio of 0.9 to 1.2 with respect to 1 equivalent of the alkali metal hydrosulfide among the total amount added. In addition, in the step of treating hydrogen sulfide, the alkali metal hydroxide may be used in an equivalent ratio of 0.2 to 0.3 with respect to 1 equivalent of the alkali metal hydrosulfide among the total amount added.

In addition, specific examples of the hydroxide of the alkali metal include lithium hydroxide, sodium hydroxide, potassium hydroxide, rubidium hydroxide, or cesium hydroxide, and any one or a mixture of two or more of these may be used. Preferably, the alkali metal hydroxide may be sodium hydroxide. In addition, in the treatment step of the reaction by-product, an aqueous solution of an alkali metal hydroxide having a concentration of 10 to 50% by weight or 10 to 40% by weight of the alkali metal hydroxide may be used. More preferably, in the treatment step of the reaction by-product, a sodium hydroxide solution having a concentration of 10 to 50% by weight or 10 to 40% by weight of the alkali metal hydroxide may be used.

According to the above method, the pH of the dehydrated liquid in the storage tank becomes neutral to weakly basic at an initial stage, becomes strongly basic after adding alkali metal hydroxide, and then supplied to the distillation column. Thereafter, when reflux proceeds through distillation of the dehydration liquid in the distillation tower, the strong alkalinity of the dehydration liquid proceeds with hydrogen sulfide throughout the dehydration process, and when it goes back to the inside of the reactor, it becomes neutral and acidic. Therefore, in this case, the pH of the dehydration solution may be adjusted to, for example, 7 to 8.5.

In addition, the dehydration liquid in the storage tank may contain water at a concentration of 70% or more (V/V%).

Meanwhile, except for the dehydration process, the dehydration reaction to provide polyarylene sulfide and the polymerization process using a sulfur source are not particularly limited and may be performed according to methods well known in the art.

For example, the polyarylene sulfide of the present invention may be subjected to a dehydration reaction (first step) and a polymerization reaction (second step) according to the method shown in FIG. 2 .

In addition, the polyarylene sulfide is obtained by dehydrating an alkali metal hydrosulfide and an alkali metal hydroxide in a mixed solvent of water and an amide compound in the presence of an organic acid salt of an alkali metal, and dehydration by the above-described method. processing the liquid; and (b) preparing polyarylene sulfide by polymerizing the sulfur source, the dihalogenated aromatic compound, and the amide-based compound.

Specifically, the sulfur source is prepared by dehydrating an alkali metal hydrosulfide and an alkali metal hydroxide in a mixed solvent of water and an amide-based compound. Accordingly, the sulfur source may include an alkali metal sulfide generated by the reaction of an alkali metal hydrosulfide and an alkali metal hydroxide, water remaining after the dehydration reaction, and a mixed solvent of an amide-based compound.

On the other hand, the sulfide of the alkali metal may be determined according to the type of hydrosulfide of the alkali metal used in the reaction, and specific examples include lithium sulfide, sodium sulfide, potassium sulfide, rubidium sulfide, or cesium sulfide. One or a mixture of two or more may be included.

In the preparation of the sulfur supply source by the reaction of the alkali metal hydrosulfide and the alkali metal hydroxide, specific examples of usable alkali metal hydrosulfides include lithium hydrogen sulfide, sodium hydrogen sulfide, potassium hydrogen sulfide, rubidium hydrogen sulfide, or cesium hydrogen sulfide. can Any one of these or a mixture of two or more thereof may be used, and anhydrides or hydrates thereof may also be used.

In addition, specific examples of the hydroxide of the alkali metal, as described above, include lithium hydroxide, sodium hydroxide, potassium hydroxide, rubidium hydroxide, or cesium hydroxide, and any one or a mixture of two or more of these may be used. . During the dehydration reaction, the alkali metal hydroxide is preferably introduced into the reactor at an equivalent ratio of 0.8 to 1.2 within an equivalent ratio of 0.9 to 1.5 with respect to 1 equivalent of the alkali metal hydrosulfide among the total amount added. Preferably, during the dehydration reaction, the alkali metal hydroxide may be used in an equivalent ratio of 0.9 to 1.2 with respect to 1 equivalent of the alkali metal hydrosulfide.

Meanwhile, in the present invention, equivalent means molar equivalent (eq/mol).

In addition, when preparing a sulfur source by the reaction of the alkali metal hydrosulfide and the alkali metal hydroxide, an organic acid salt of an alkali metal capable of increasing the degree of polymerization of polyarylene sulfide in a short time by accelerating the polymerization reaction is added as a polymerization aid It 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 these 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 more specifically 0.05 to 0.5, based on 1 equivalent of the alkali metal hydrosulfide.

The reaction of the alkali metal hydrosulfide and the alkali metal hydroxide may be carried out in a mixed solvent of water and an amide compound. Specific examples of the amide compound include 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 phosphoric acid amide compounds such as hexamethylphosphoric acid triamide, and the like, any one or a mixture of two or more of these may be used. Among them, the amide-based compound may be N-methyl-2-pyrrolidone (NMP) in more detail, considering reaction efficiency and co-solvent effect as a polymerization solvent during polymerization for producing polyarylene sulfide.

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

Meanwhile, in the above step, a reactant including an alkali metal hydrosulfide and an alkali metal hydroxide may generate an alkali metal sulfide through dehydration. At this time, the dehydration reaction may be carried out by stirring at a temperature range of about 130 to 205 ℃, at a speed of about 100 to 500 rpm. More specifically, it may be performed by stirring at a speed of about 100 to 300 rpm in a temperature range of about 175 to 200 °C. 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 this dehydration process, solvents such as water among the reactants may be removed through distillation, etc., and some of the amide-based compounds are discharged along with water, and some sulfur contained in the sulfur source reacts with water by heat during the dehydration process to obtain It can volatilize as hydrogen sulfide gas.

Meanwhile, as a result of the reaction of the alkali metal hydrosulfide, alkali metal hydroxide, and alkali metal salt as described above, the alkali metal sulfide is precipitated as a solid in a mixed solvent of water and an amide compound. Accordingly, when a sulfur source prepared by reacting a hydrosulfide of an alkali metal and a hydroxide of an alkali metal is used as a sulfur source in the production of polyarylene sulfide according to the present invention, the molar ratio of the sulfur source is the alkali metal added during the reaction. is taken as the molar ratio of the hydrosulfide of

Subsequently, a dehydration process is performed to remove solvents such as water in the reaction products including alkali metal sulfides produced as a result of the above reaction. The dehydration process may be performed according to the method 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 since the generated hydrogen sulfide is volatilized, the hydrogen sulfide volatilized out of the system during the dehydration process remains in the system after the dehydration process. The amount of sulfur in the sulfur source may be reduced. For example, when a sulfur source containing alkali metal hydrosulfide as a main component is used, the amount of sulfur remaining in the system after the dehydration process is equal to the molar amount of hydrogen sulfide volatilized out of the system minus the molar amount of sulfur in the added 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 the molar ratio of water to 1 mole of available sulfur is 1 to 5, more specifically 1.5 to 4, more specifically 1.75 to 3.5. When the moisture content in the sulfur source is excessively reduced by the dehydration process, the moisture content may be adjusted by adding water prior to the polymerization process.

In addition, in the present invention, since the pH of the dehydration liquid is adjusted as described above to treat the hydrogen sulfide volatilized in this process, it is possible to treat hydrogen sulfide more easily than in the prior art and provide it as a sulfur source.

Accordingly, the sulfur source prepared by the reaction and dehydration of an alkali metal hydrosulfide and an alkali metal hydroxide as described above may include a mixed solvent of water and an amide-based compound together with an 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 included in the sulfur source. In addition, the sulfur source may further include an alkali metal hydroxide produced by a reaction between sulfur and water.

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

Dihalogenated aromatic compounds usable for the production of the polyarylene sulfide are compounds in which two hydrogens in an aromatic ring are substituted with halogen atoms, and specific examples include o-dihalobenzene, m-dihalobenzene, and p-dihal. lowbenzene, dihalotoluene, dihalonaphthalene, dihalobiphenyl, dihalobenzoic acid, dihalodiphenyl ether, dihalodiphenyl sulfone, dihalodiphenyl sulfoxide, or dihalodiphenyl ketone; any one of these or Mixtures of two or more may be used. In the dihalogenated aromatic compound, the halogen atom may be fluorine, chlorine, bromine or iodine. Among them, p-dichlorobenzene (p-DCB) may be used in consideration of reactivity and side reaction generation reduction effect when producing polyarylene sulfide.

The dihalogenated aromatic compound may be added in an equivalent amount of about 0.8 to 1.2 based on 1 equivalent of the sulfur source. When the amount is added within the above range, polyarylene sulfide having excellent physical properties can be prepared without worrying about a decrease in the melt viscosity of the polyarylene sulfide and an increase in the chlorine content present in the polyarylene sulfide. there is. Considering the superiority of the improvement effect by controlling the sulfur source and the addition amount of the dihalogenated aromatic compound, more specifically, the dihalogenated aromatic compound may be added in an equivalent amount of about 0.9 to 1.1.

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

In addition, the above-mentioned polymerization reaction between the sulfur source and the 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 against alkali at a high temperature.

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

Since the amide-based compound included in the sulfur source in the first step can act as a co-solvent, the amide-based compound added in the second step has a molar ratio of water (H ₂ O) to the amide-based compound present in the polymerization reaction system (molar ratio of water/amide-based compound) may be added in an amount such that it is about 0.85 or more.

In addition, during the polymerization reaction, other additives for controlling the polymerization reaction or molecular weight, such as a molecular weight regulator and a crosslinking agent, may be further added in an amount within a range that does not deteriorate the physical properties and production yield of the finally produced polyarylene sulfide.

The polymerization reaction between the sulfur source and the dihalogenated aromatic compound may be performed at about 200 to 300 °C. Alternatively, it may be performed in multiple steps while changing the temperature within the above temperature range. Specifically, after the primary polymerization reaction at about 200 ° C. or more and less than about 250 ° C., the secondary polymerization reaction is continuously performed at a temperature higher than the temperature during the primary polymerization reaction, specifically at about 250 ° C. to 300 ° C. can

The reaction product produced as a result of the polymerization reaction is separated into an aqueous phase and an organic phase, and polyarylene sulfide, which is a polymerization reaction product, is dissolved and included in the organic phase. Accordingly, a process for precipitating and separating the polyarylene sulfide produced may be optionally further performed.

Specifically, the precipitation of the polyarylene sulfide may be performed by adding water to the reaction mixture in an equivalent ratio of about 3 to 5 based on 1 equivalent of sulfur, followed by cooling. When water is added in the above content range, polyarylene sulfide can be precipitated with excellent efficiency.

Thereafter, the precipitated polyarylene sulfide may be selectively further subjected to washing and filtering and drying processes according to a conventional method.

For a specific method of preparing the polyarylene sulfide, reference may be made to Examples to be described later. However, the manufacturing method of polyarylene sulfide is not limited to the content described herein, and the manufacturing method may additionally employ steps commonly employed in the technical field to which the present invention belongs, and of the manufacturing method The step(s) can be varied by the conventionally variable step(s).

As described above, the method of the present invention can effectively reduce air pollution due to hydrogen sulfide, reduce the scrubber capacity, and minimize the loss of sulfur sources, thereby increasing the production of polyarylene sulfide.

In addition, the polyarylene sulfide is produced in a yield of about 60% or more or 65 to 75% or more, and may have a melt viscosity (MV) of 10 to 200 PaS. The melt viscosity (MV) of the polyarylene sulfide is changed by melting polyarylene sulfide (eg, PPS) in an N ₂ atmosphere using an ARES-G2 rheometer and frequency sweeping to change the viscosity It can be obtained by checking and measuring the value when the frequency is 0.10 Hz as melt viscosity (MV). The polyarylene sulfide may have a melting temperature (Tm) of 270 to 300 °C and a crystallization temperature (Tc) of 180 to 250 °C. In addition, the polyarylene sulfide may have a weight average molecular weight (Mw) greater than 10,000 g/mol and less than 50,000 g/mol.

In addition, the polyarylene sulfide of the present invention exhibits excellent fluidity and can exhibit improved miscibility with fillers or reinforcing agents. As a result, it can be useful in the manufacture of molded articles for metal replacement in automobiles, electrical and electronic products, or mechanical parts, especially in the manufacture of reflectors and base plates for automobile lamps requiring excellent mechanical properties.

Hereinafter, the action and effect of the invention will be described in more detail through specific examples of the invention. However, this is presented as an example of the invention, and thereby the scope of the invention is not limited in any sense.

Comparative Example 1

(a) dewatering process

1.01 equivalent of 70% sodium hydrogen sulfide (NaSH) and 1.05 equivalent of sodium hydroxide (NaOH), 0.44 equivalent of sodium acetate (NaOAc) powder and 1.65 equivalent of N-methyl-2-pyrrolidone (NMP), 4.72 equivalent of deionized Ionized water (DI water) was put into the reactor, and the reactor was fastened. At this time, the material of the reactor is titanium, and the limit pressure is 40 bar.

The reactor was heated to 186.1° C. for 50 minutes while stirring at 500 rpm to collect 414 ml of dehydration liquid. N ₂ gas was flowed into the reactor at 2.5 L/min so that H ₂ S escaped from the inside of the reactor. When the dehydration valve is opened and the temperature is gradually raised, dehydrated water starts to come out from the inside of the reactor. Thereafter, when the temperature of the reactor reached 200° C., the dehydration valve and the N ₂ gas were closed, and the heater was turned off to lower the temperature.

At this time, the concentration (v / v%) of water in the dehydration solution measured by Karl-Fisher was 71.80%, and the pH of the dehydration solution was measured as 10.32. In addition, the S ^2- concentration of the dehydration solution was 82 mg/L, and the S ^2- concentration that was not recovered was 748 mg/L.

(b) polymerization reaction

After lowering the temperature of the reactor containing the sulfur source obtained through the dehydration reaction to less than 170 ° C., 1.10 equivalents of para-dichlorobenzene (p-DCB) and 1.35 equivalents of NMP were added to the reactor. At this time, the molar ratio of NMP/S was calculated as 2.68. Then, the obtained mixed solution was heated to 230°C and reacted for 2 hours, and then heated to 250°C and reacted for further 2 hours. After completion of the reaction, distilled water in a ratio of 3 equivalents to 1 equivalent of sulfur present in the reactor was added into the reactor, and the product was recovered after sufficiently lowering the temperature. The resulting product was washed sequentially with a mixture of distilled water and NMP (mixed volume ratio = 1:1) and distilled water, then filtered, washed with NMP for 10 minutes at 90 ° C, filtered, and then washed with 0.4% aqueous acetic acid at 90 °C. After washing at ° C., filtering was performed, followed by filtering with distilled water at 90 ° C. for 10 minutes. The washed polyphenylene sulfide was recovered by drying in a vacuum oven at 150 °C for 8 hours.

The yield of polyphenylene sulfide recovered at this time was 82.9%, and the melting rate was 660.2 g/10 min.

Comparative Example 2

(a) PPS was provided using the method of Comparative Example 1, except that the dehydration process was performed as follows.

That is, 1.01 equivalents of 70% sodium hydrogen sulfide (NaSH), 1.05 equivalents of sodium hydroxide (NaOH), 0.44 equivalents of sodium acetate (NaOAc) powder and 1.65 equivalents of N-methyl-2-pyrrolidone (NMP), 4.72 equivalents of deionized water (DI water) was put into the reactor, and the reactor was fastened. At this time, the material of the reactor is titanium, and the limit pressure is 40 bar.

The reactor was heated to 179.5° C. for 45 minutes while stirring at 500 rpm to collect 417 ml of dehydrated liquid. N ₂ gas was flowed into the reactor at 10 L/min so that H ₂ S escaped from the inside of the reactor. When the dehydration valve is opened and the temperature is gradually raised, dehydrated water starts to come out from the inside of the reactor. Then, when the reactor temperature reached 200 °C, the dehydration valve and N2 gas were closed, and the heater was turned off to lower the temperature.

At this time, the concentration (v / v%) of water in the dehydration solution measured by Karl-Fisher was 70.21%, and the pH of the dehydration solution was measured to be 10.33. In addition, the S ^2- concentration of the dehydration solution was 70 mg/L, and the S ^2- concentration that was not recovered was 994 mg/L.

The yield of recovered polyphenylene sulfide was 81.8%, and the melting rate was 688.1 g/10 min.

Example 1

(a) dewatering process

1.01 equivalent of 70% sodium hydrogen sulfide (NaSH) and 1.05 equivalent of sodium hydroxide (NaOH), 0.44 equivalent of sodium acetate (NaOAc) powder and 1.65 equivalent of N-methyl-2-pyrrolidone (NMP), 4.72 equivalent of deionized Ionized water (DI water) was put into the reactor, and the reactor was fastened. At this time, the material of the reactor is titanium, and the limit pressure is 40 bar.

The reactor was heated to 195.5 ° C. for 1 hour while stirring at 500 rpm, and 428 ml of dehydration liquid was collected in a storage tank through a dehydration reaction. Unlike Comparative Examples 1 and 2, the pH was adjusted to weakly basic by adding a 40% by weight sodium hydroxide solution to the dehydration solution so that H ₂ S did not escape. Thereafter, after distilling and reducing the dehydrated liquid adjusted to be weakly basic, the reaction product (Na2S) was supplied back to the reactor.

At this time, the initial pH of the 40% by weight sodium hydroxide solution was 14.35. Thereafter, hydrogen sulfide in the 40% by weight sodium hydroxide solution and the dehydration solution reacted with NaOH to lower the basicity of the dehydration solution to pH 7.02.

Through the above results, the concentration (v/v%) of water in the dewatering liquid measured by Karl-Fisher was 73.72%. In addition, the S ^2- concentration of the dehydration solution was 482 mg/L, and the S ^2- concentration that was not recovered was 180 mg/L.

(b) polymerization reaction

As shown in FIG. 2, after the dehydration reaction, para-dichlorobenzene was reacted with a sulfur source to prepare polyphenylene sulfide.

After lowering the temperature of the reactor containing the sulfur source obtained through the dehydration reaction to less than 170 ° C., 1.10 equivalents of para-dichlorobenzene (p-DCB) and 1.35 equivalents of NMP were added to the reactor. At this time, the molar ratio of NMP/S was calculated as 2.68. Then, the obtained mixed solution was heated to 230°C and reacted for 2 hours, and then heated to 250°C and reacted for further 2 hours. After completion of the reaction, distilled water in a ratio of 3 equivalents to 1 equivalent of sulfur present in the reactor was added into the reactor, and the product was recovered after sufficiently lowering the temperature. The resulting product was washed sequentially with a mixture of distilled water and NMP (mixed volume ratio = 1:1) and distilled water, then filtered, washed with NMP for 10 minutes at 90 ° C, filtered, and then washed with 0.4% aqueous acetic acid at 90 °C. After washing at ° C., filtering was performed, followed by filtering with distilled water at 90 ° C. for 10 minutes. The washed polyphenylene sulfide was recovered by drying in a vacuum oven at 150 °C for 8 hours.

The yield of recovered polyphenylene sulfide was 90.3%, and the melting rate was 458.7 g/10min.

Example 2

In the dehydration process, PPS was provided using the method of Example 1, except that a 10% by weight sodium hydroxide solution was added to the dehydration solution.

(a) Dehydration process

1.01 equivalents of 70% sodium hydrogen sulfide (NaSH) and 1.05 equivalents of sodium hydroxide (NaOH), 0.44 equivalents of sodium acetate (NaOAc) powder and 1.65 equivalents of N-methyl-2-pyrrolidone (NMP), 4.72 equivalents of deionized Ionized water (DI water) was put into the reactor, and the reactor was fastened. At this time, the material of the reactor is titanium, and the limit pressure is 40 bar.

In addition, the reactor was heated to 192.6 ° C. for 1 hour while stirring at 500 rpm to collect 410 ml of dehydration solution. Unlike Comparative Examples 1 and 2, a 10% by weight sodium hydroxide solution was added to the dehydration solution so that H ₂ S did not escape, and the pH was adjusted to be weakly basic.

At this time, the initial pH of the 10% by weight sodium hydroxide solution was 13.40. Thereafter, hydrogen sulfide in the 40% by weight sodium hydroxide solution and the dehydration solution reacted with NaOH, so that the pH of the dehydration solution was lowered to 8.37 in basicity.

Through the above results, the concentration (v/v%) of water in the dewatering liquid measured by Karl-Fisher was 73.72%. In addition, the S ^2- concentration of the dehydration solution was 280 mg/L, and the S ^2- concentration that was not recovered was 253 mg/L.

(b) polymerization reaction

After lowering the temperature of the reactor including the sulfur source obtained through the dehydration reaction to less than 170 ° C., 1.10 equivalents of para-dichlorobenzene (p-DCB) and 1.35 equivalents of NMP were added to the reactor. At this time, the molar ratio of NMP/S was calculated as 2.68. Then, the obtained mixed solution was heated to 230°C and reacted for 2 hours, and further heated to 250°C and reacted for 2 hours. After completion of the reaction, distilled water in a ratio of 3 equivalents to 1 equivalent of sulfur present in the reactor was added into the reactor, and the temperature was sufficiently lowered to recover the product. The resulting product was washed sequentially with a mixture of distilled water and NMP (mixed volume ratio = 1:1) and distilled water, then filtered, washed with NMP for 10 minutes at 90 ° C., filtered, and then washed with 0.4% aqueous acetic acid at 90 After washing at ° C., filtering was performed, followed by filtering with distilled water at 90 ° C. for 10 minutes. The washed polyphenylene sulfide was recovered by drying in a vacuum oven at 150 °C for 8 hours.

The yield of recovered polyphenylene sulfide was 87.7%, and the melting rate was 560.0 g/10min.

Claims (8)

A dehydration process including dehydration of alkali metal hydrosulfides, alkali metal hydroxides and organic acid salts of alkali metals and treatment of reaction by-products in a mixed solvent of water and amide-based compounds is performed to obtain a sulfur source including alkali metal sulfides. providing; and
Preparing polyarylene sulfide by polymerizing the sulfur source, the dihalogenated aromatic compound, and the amide-based compound; Including,
In the step of treating the reaction by-products, a dehydration solution containing hydrogen sulfide generated as a by-product of the dehydration reaction is collected, and an alkali metal hydroxide is added to the dehydration solution collected without separation of by-products and water to adjust the basicity of the dehydration solution to a pH of 10 to 10. After adjusting to 15, distilling and refluxing the dehydration liquid to form a sulfide of an alkali metal;
Method for producing polyarylene sulfide.
The method of claim 1, wherein the dehydration step
Hydrogen sulfide of alkali metal, hydroxide of alkali metal, and organic acid salt of alkali metal are subjected to dehydration reaction in a mixed solvent of water and amide-based compound to produce sulfide of alkali metal, mixed solvent of water and amide-based compound, and by-product hydrogen sulfide. A first step of providing a sulfur source while discharging the dehydration liquid;
The discharged dehydration liquid is distilled to separate the amide-based compound in the mixed solvent and refluxed in the first step, and the dehydration liquid including hydrogen sulfide, water, and the amide-based compound not separated in the distillation are distilled by-products of the dehydration liquid The second step of collecting; and
A third step of injecting alkali metal hydroxide into the collected dehydration solution to adjust the basicity of the dehydration solution to pH 10 to 15, and then distilling and refluxing the dehydration solution to form alkali metal sulfides to treat reaction by-products; including,
Method for producing polyarylene sulfide comprising a.
According to claim 2,
Supplying the sulfide of the alkali metal obtained in the third step to the first step as a sulfur source; method for producing polyarylene sulfide further comprising.
According to claim 1,
The alkali metal hydroxide is
It is used in an equivalent ratio of 0.9 to 1.5 with respect to 1 equivalent of alkali metal hydrosulfide,
A method for producing polyarylene sulfide, which is divided and introduced at a ratio of 1: 0.1 to 0.3 in the dehydration reaction and the treatment of reaction by-products within the above equivalence ratio range.
According to claim 1,
The alkali metal hydroxide is within the range of an equivalent ratio of 0.9 to 1.5 with respect to 1 equivalent of the alkali metal hydrosulfide,
In the dehydration reaction, an equivalent ratio of 0.8 to 1.2 is introduced into the reactor with respect to 1 equivalent of alkali metal hydrosulfide,
In the processing step of the reaction by-product, a method for producing polyarylene sulfide that is used by introducing it into a storage tank at an equivalent ratio of 0.1 to 0.3 with respect to 1 equivalent of alkali metal hydrosulfide.
According to claim 1,
In the step of treating the reaction by-products, the alkali metal hydroxide is a method for producing polyarylene sulfide using a sodium hydroxide solution at a concentration of 10 to 50% by weight.
delete According to claim 2,
In the third step, the method for producing polyarylene sulfide having a pH of 7 to 8.5 after distillation of the dehydration liquid.

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