KR102489249B1 - Method and apparatus for preparing polyphenylene sulfide - Google Patents

Abstract

The present invention relates to a method and apparatus for producing polyphenylene sulfide, and more particularly, to a reactor; distillation column; condenser; And a tank for collecting the condensed dehydration solution; injecting a mixture including sulfide, alkali metal hydroxide, alkali metal carboxylate, polar organic solvent and water into a dehydration reaction apparatus including a tank, and heating the dehydration reaction. However, the dehydration reaction relates to a method and apparatus for producing polyphenylene sulfide, characterized in that the pressure is reduced during the reaction.
According to the present invention, by applying reduced pressure during the dehydration reaction, energy consumption is reduced and heat transfer is efficient, thereby reducing batch time and improving productivity, minimizing loss of polar organic solution in the dehydration solution under predetermined operating conditions, and generating by-products such as hydrogen sulfide. pipe corrosion is minimized, and the equipment replacement cycle is extended, and sulfur does not disappear, making it easy to manage the physical properties of polyphenylene sulfide resin during polymerization and the final product after polymerization. There is an effect of providing a method and apparatus for producing polyphenylene sulfide with less ring generation.

Description

Method and apparatus for producing polyphenylene sulfide {METHOD AND APPARATUS FOR PREPARING POLYPHENYLENE SULFIDE}

The present invention relates to a method for producing polyphenylene sulfide and an apparatus for producing the same, and more particularly, by applying reduced pressure during a dehydration reaction, energy consumption is low and heat transfer is efficient, thereby reducing batch time and improving productivity, and under predetermined operating conditions. As a result, the loss of polar organic solution in the dehydration liquid is minimized, and the generation of by-products such as hydrogen sulfide is minimized, and pipe corrosion is minimized, and furthermore, the equipment replacement cycle is extended, and the loss of sulfur does not occur, resulting in a final product after polymerization with polyphenylene sulfide resin during polymerization. The present invention relates to a method for producing polyphenylene sulfide that is easy to manage physical properties of a product and reduces fouling in a reactor by applying a jacket type to a heat exchanger and an apparatus for manufacturing the same.

BACKGROUND OF THE INVENTION Recently, demand for thermoplastic resins having high heat resistance and good chemical resistance as materials for parts of electric/electronic devices or parts of chemical devices is increasing. Polyphenylene sulfide (PPS), one of these thermoplastic resins, has excellent strength, processability, chemical resistance, and heat resistance, and is particularly in the limelight as a filter material.

Polyphenylene sulfide is usually produced by polycondensation of sodium sulfide and p-chlorobenzene. Sodium sulfide raw material can be obtained, for example, by the dehydration reaction of sodium hydrosulfide and sodium hydroxide. When sodium acetate is used together as a polymerization aid, linear high molecular weight polyphenylene sulfide can be obtained. can

NMP (N-methyl-2-pyrrolidone) is usually used as the solvent for the polycondensation reaction. When hydrated sodium sulfide is dissolved in NMP at high temperature, a part of NMP is hydrolyzed and SMAB (Sodium-4-(N-methylamino) )-butanoate) and sodium hydrogen sulfide, and it is known that this mixture acts as an active nucleophile.

In order to obtain a sulfur compound, which is a raw material of the polycondensation reaction, for example, sodium hydroxide, sodium hydrogen sulfide, sodium acetate, NMP, etc. are added as raw materials and a dehydration reaction is performed. This dehydration reaction is usually carried out at normal pressure and the temperature is raised to a high temperature This is done while removing water from the reaction system.

In addition, the production process of polyphenylene sulfide includes a polycondensation reaction process, a washing process, and a solvent recovery process, and the polycondensation reaction process is operated in batch mode due to the phase and polymerization characteristics of raw materials.

However, the conventional polyphenylene sulfide manufacturing process consumes excessive energy due to the nature of the process to volatilize water, takes a long time to place due to heat transfer efficiency problems, and causes pipe corrosion and salts caused by by-products such as H ₂ S. There was a problem that fouling was induced due to the characteristics of many reaction systems.

Korean Patent Publication No. 2007-01128515

In order to solve the problems of the prior art as described above, the present invention reduces energy consumption by applying reduced pressure during the process and heat transfer is efficient, so that the batch time is reduced and productivity is improved, and the polar organic solution in the dehydration solution is lost under predetermined operating conditions. pipe corrosion is minimized and the generation of by-products such as hydrogen sulfide is minimized, and furthermore, the equipment replacement cycle is extended, and sulfur is not lost, so it is easy to manage the physical properties of the final product after polymerization with polyphenylene sulfide resin during polymerization, and heat exchange It is an object of the present invention to provide a method and apparatus for producing polyphenylene sulfide with less fouling in the reactor by applying a jacket form to the reactor.

The above and other objects of the present invention can all be achieved by the present invention described below.

In order to achieve the above object, the present invention is a reactor; distillation column; condenser; And a tank for collecting the condensed dehydration solution; injecting a mixture including sulfide, alkali metal hydroxide, alkali metal carboxylate, polar organic solvent and water into a dehydration reaction apparatus including a tank, and heating the dehydration reaction. However, the dehydration reaction provides a method for producing polyphenylene sulfide, characterized in that the pressure is reduced during the reaction.

In addition, the present invention includes a reactor, a distillation column, a condenser, and a tank for collecting condensed dewatered liquid, wherein the distillation column includes a packing column, the reactor includes a paddle-shaped stirrer and a spiral baffle jacket, , It provides an apparatus for producing polyphenylene sulfide, characterized in that a vacuum pump capable of reducing pressure during the reaction is installed in the vent line leading to the top of the distillation column.

According to the present invention, energy consumption is reduced and heat transfer is efficient by applying reduced pressure during the process, thereby reducing batch time and improving productivity, minimizing the loss of polar organic solution in the dehydration solution under predetermined operating conditions, and minimizing the generation of by-products such as hydrogen sulfide. pipe corrosion is minimized, and the equipment replacement cycle is extended, and sulfur does not disappear, making it easy to manage the physical properties of polyphenylene sulfide resin during polymerization and the final product after polymerization. There is an effect of providing a method and apparatus for producing polyphenylene sulfide with little production.

1 is a diagram schematically showing a dehydration reaction apparatus including a reactor, a distillation column, a condenser, and a dehydration liquid tank used in Comparative Examples 1 to 3.
2 is a diagram schematically showing a dehydration reaction apparatus including a reactor, a distillation tower, a condenser, a dehydration liquid tank, and a pressure reducing device used in Examples 1 to 4.
3 is an overall process diagram schematically showing dehydration (reaction), polymerization (reaction), crystallization, filtering, washing, and drying steps of the method for producing polyphenylene sulfide according to the present disclosure.

Hereinafter, the manufacturing method and manufacturing apparatus of the polyphenylene sulfide of the present description will be described in detail.

The present inventors have found that, when predetermined pressure reduction conditions and operating conditions are applied to the dehydration reaction to produce the sulfur source used in the polymerization of polyphenylene sulfide, energy consumption is low and heat transfer is efficient, thereby reducing batch time and improving productivity. The loss of polar organic solvent is minimized and the generation of by-products such as hydrogen sulfide is minimized, pipe corrosion is minimized, and furthermore, the equipment replacement cycle is extended and sulfur is not lost. It was easy, and it was confirmed that the fouling in the reactor was small, and based on this, further research was devoted to completing the present invention.

The method for producing polyphenylene sulfide of the present invention includes a reactor; distillation column; condenser; And a tank for collecting the condensed dehydration solution; injecting a mixture including sulfide, alkali metal hydroxide, alkali metal carboxylate, polar organic solvent and water into a dehydration reaction apparatus including a tank, and heating the dehydration reaction. However, the dehydration reaction is characterized in that the pressure is reduced during the reaction. In this case, energy efficiency, productivity, pipe corrosion resistance, quality stability, etc. are excellent, the device replacement cycle is extended, and there is an effect that less or no fouling is generated in the device.

The reactor may include, for example, a paddle-type agitator and a spiral baffle jacket, and in this case, fouling formation in the reactor may be reduced or not formed.

The paddle-type agitator may be composed of a motor, a shaft, and a propellant as an example, and may be composed of a motor, a drive, a shaft, and a propellant as another example, and in this case, there is an effect that the reaction proceeds stably.

The drive is a connector connecting a motor and a shaft, and is used as a meaning including all of a shaft connector, a motor shaft coupling, a drive, and the like, and is not limited by the name.

The spiral baffle jacket is not particularly limited if it is a spiral baffle jacket commonly used in the technical field to which the present invention belongs.

The distillation column may be, for example, a packing column, and in this case, the loss of polar organic solvent in the dehydration liquid is minimized, and the generation of by-products such as hydrogen sulfide is suppressed to minimize pipe corrosion, and furthermore, the equipment replacement cycle is extended and sulfur Since loss does not occur, it is effective in managing the physical properties of the polyphenylene sulfide resin during polymerization and the final product after polymerization.

The packing column is a distillation apparatus as opposed to a tray column, and is not particularly limited in the case of a packing column usable in the art to which the present invention belongs, but, for example, a Raschig ring, a Pall ring , CMR ring (CMR ring), IMTP ring (IMTP ring), Berl saddle (Berl saddle) and metal high pack (Metal Hypac) can be a packing column filled with one or more kinds of packing material selected from the random packing group, In this case, the abnormal pressure drop is small, and it is easy to use the pressure reducing system as in the present invention, and the loss of the polar organic solution and the generation of by-products are minimized.

The height or capacity of the distillation column may be adjusted according to the capacity of the reactor, and is not particularly limited in the range commonly used in the art to which the present invention belongs, and may be appropriately selected as needed.

A portion of the condensate condensed in the condenser may, for example, be recovered to a distillation tower, and in this case, loss of the polar organic solvent in the condensate, that is, the dehydration liquid, is minimized.

The dehydration reaction device may include, for example, a pressure reducing device, and in this case, there is an effect of significantly improving productivity due to high heat transfer efficiency.

The decompression device is not particularly limited when it is a decompression device commonly used in the technical field to which the present invention belongs, and may be, for example, a vacuum pump. In this case, the heat transfer efficiency is high, and productivity is greatly improved.

The pressure reducing device may be installed, for example, in a vent line leading to the top of the distillation column, preferably installed at the rear end of the dehydration tank, and may be connected to the upper vent line of the dehydration tank as a specific example. In this case, the pressure reduction proceeds stably and the heat transfer efficiency is high, so the productivity is greatly improved.

In the present description, a vent line refers to a line or pipe connected from a reactor vent to the atmosphere unless otherwise limited.

The dehydration reaction device may further include, for example, a pressure sensor, and in this case, the reaction proceeds stably and the heat transfer efficiency is high, thereby greatly improving productivity.

The pressure sensor is not particularly limited if it is a pressure sensor commonly used in the technical field to which the present invention belongs.

The sulfide may be, for example, at least one selected from the group consisting of alkali metal bisulfate, alkali metal hydrosulfide and alkali metal sulfide, preferably alkali metal hydrosulfide or alkali metal sulfide, and more preferably alkali metal. It is a hydrosulfide, and in this case, there is an effect of excellent reactivity, economy and productivity.

The alkali metal may be, for example, lithium, sodium, or potassium, preferably sodium, and in this case, when polyphenylene sulfide is produced, reactivity, economy, and productivity are excellent.

The sulfide reacts with an alkali metal hydroxide in a dehydration reaction to form an alkali metal sulfide and then polymerizes with a dihalogenated aromatic compound to form polyphenylene sulfide.

The alkali metal hydroxide may be, for example, at least one selected from the group consisting of sodium hydroxide, potassium hydroxide, lithium hydroxide, and cesium hydroxide, and is preferably sodium hydroxide, and in this case, the reactivity and physical property balance are excellent.

The alkali metal carboxylate is used as a polymerization aid to accelerate the polymerization reaction, thereby increasing the degree of polymerization of polyphenylene sulfide in a short time. For example, alkali metal acetate, alkali metal hexanoate and alkali metal benzoate. It is at least one selected from the group, preferably an alkali metal acetate, and in this case, the reactivity is good and the effect of controlling the molecular weight of polyphenylene sulfide is excellent. At this time, the alkali metal may be, for example, lithium, sodium or potassium, preferably sodium, for the same reason as described above.

The polar organic solvent is, for example, alcohol, alkylene oxide, hexamethylphosphoramide, tetramethylurea, N,N'-ethylenedipyrrolidone, N-methyl-2-pyrrolidone, pyrrolidone, caprolactam, It may be at least one selected from the group consisting of N-ethylcaprolactam, sulfolane, N,N'-dimethylacetamide and 1,3-dimethyl-2-imidazolidinone, and in this case, the reaction is good and the reaction proceeds smoothly. has the effect of

The alcohol and alkylene oxide are not particularly limited if they are types commonly used as polar organic solvents in the art to which the present invention belongs.

The mixture may include, for example, 1 equivalent of a sulfide, 0.5 to 2 equivalents of an alkali metal hydroxide, 0.01 to 1.5 equivalents of an alkali metal carboxylate, 1 to 5 equivalents of a polar organic solvent, and 1 to 15 equivalents of water, within this range. It has excellent reactivity, productivity and economy, and excellent physical properties of polyphenylene sulfide.

For example, the alkali metal hydroxide may be used in an amount of 0.5 to 1.5 equivalents or 0.8 to 1.2 equivalents based on 1 equivalent of sulfide, and within this range, the physical properties of polyphenylene sulfide are excellent.

The alkali metal carboxylate may be used, for example, in an amount of 0.05 to 1.5 equivalent or 0.05 to 1 equivalent based on 1 equivalent of sulfide, and within this range, the physical properties of polyphenylene sulfide are excellent.

The polar organic solvent may be used, for example, in an amount of 2 to 5 equivalents, or 3 to 5 equivalents, and water in an amount of 2 to 12 equivalents, or 4 to 10 equivalents, based on 1 equivalent of sulfide.

The reflux ratio of the distillation column and the condenser may be, for example, in the range of 0.1 to 1.0, and preferably in the range of 0.3 to 0.7, in which case the loss of the polar organic solution in the dehydration liquid is minimized and the productivity is excellent.

In the present description, the reflux ratio is calculated by dividing the mass flow rate refluxed to the distillation column by the mass flow rate removed to the outside air.

The condenser is not particularly limited if it is a condenser commonly used in the technical field to which the present invention belongs.

The reactor may be operated under conditions of a dehydration temperature of 100 to 130° C. lower than the polymerization temperature of polyphenylene sulfide and a dehydration pressure condition lower than the polymerization pressure of polyphenylene sulfide. Within this range, a part of the polar organic solvent and water are effectively removed, the loss of the polar organic solvent in the dehydration solution is minimized, and the generation of by-products such as hydrogen sulfide is minimized, minimizing pipe corrosion, and furthermore, the equipment replacement cycle is extended, and the loss of sulfur Since this does not occur, it is easy to manage the physical properties of the polyphenylene sulfide resin during polymerization and the final product after polymerization.
The reduced pressure may be carried out as a stepwise, gradual or continuous pressure reduction, for example, from normal pressure to 0.8 to 0.04 bar, 0.7 to 0.1 bar, preferably 0.4 to 0.1 bar, more preferably 0.2 to 0.1 bar, preferably gradual. Alternatively, it is carried out under continuous pressure reduction, and in this case, energy consumption is low and heat transfer is efficient during the process, thereby reducing batch time, improving productivity, reducing or eliminating fouling, and minimizing loss of polar organic solution.

The gradual or continuous pressure reduction may drop to, for example, 0.001 to 0.1 bar/min or 0.001 to 0.01 bar/min, preferably 0.002 to 0.009 bar/min or 0.005 to 0.009 bar/min, and most preferably 0.006 to 0.009 bar/min, and within this range, energy consumption during the process is low and heat transfer is efficient, so batch time is reduced, productivity is improved, fouling is reduced or not, and loss of polar organic solution is minimized. there is

In the present description, the stepwise, gradual or continuous pressure reduction is not particularly limited in the case of stepwise, gradual or continuous pressure reduction methods commonly known in the art, and for example, stepwise pressure reduction is one step, two steps or Reducing the pressure in three or more steps means reaching the target pressure, and gradual pressure reducing means reaching the target pressure by continuously dropping a certain pressure per certain time interval during the reaction. The depressurization method means reaching a target pressure by continuously dropping the pressure without interruption or equal pressure section during the reaction.

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The termination of the dehydration reaction may be appropriately adjusted in time in consideration of productivity, economy, and physical properties of the final product, but, for example, it may be determined by the amount of dehydration liquid collected in the dehydration liquid tank, and as a specific example, it may be vaporized after the reaction. The dehydration reaction is terminated when 70 to 90% by weight or 75 to 85% by weight of the total amount of water in the water is collected in the dehydration liquid tank, another example is 1 hour to 3 hours, preferably 1 hour to 2 hours 10 minutes , More preferably, the reaction is carried out for 1 hour 30 minutes to 2 hours and then terminated. Within this range, the generation of by-products such as hydrogen sulfide is small, pipe corrosion is minimized, and furthermore, the equipment replacement cycle is extended and no loss of sulfur occurs. It is effective in managing the physical properties of the polyphenylene sulfide resin during polymerization and the final product after polymerization.

The method for producing the polyphenylene sulfide, for example, includes a) adding a dihalogenated aromatic compound and a polar organic solvent to a mixture containing an alkali metal sulfide remaining in the reactor after the dehydration reaction, followed by a polymerization reaction to obtain a polymerization product; b) crystallizing or precipitating the polymerization product by lowering the temperature after the polymerization reaction; c) filtering after crystallization or precipitation of the polymerization product to remove the polar organic solvent and residual reactants; d) washing the polymerization product obtained after the filtration with a washing solution and dehydrating; and e) drying the dehydrated polymerization product.

The alkali metal sulfide may be, for example, Na ₂ S.

The dihalogenated aromatic compound may be selected from various types, and examples include p-dichlorobenzene, m-dichlorobenzene, o-dichlorobenzene, 1,3,5-trichlorobenzene, and 1,2,4-trichlorobenzene. , 1,2,4,5-tetrachlorobenzene, hexachlorobenzene, 2,5-dichlorotoluene, 2,5-dichloro-p-xylene, 1,4-dibromobenzene, 1,4-diiodobenzene , and 1-methoxy-2,5-dichlorobenzene may be at least one selected from polyhalogenated aromatic compounds, and a halogen end group, specifically a chlorine end group, may be introduced into polyphenylene sulfide. Dihalogen benzene is preferred. Dihalogenated aromatic compounds may be used alone or in combination of two or more, if necessary.

The dihalogenated aromatic compound (DH) may have an equivalence ratio (S/DH) of 0.5 to 1.5 or 0.9 to 1.2, for example, with the sulfide used in the above-described dehydration reaction, and within this range, an excellent physical property balance effect is obtained. there is.

For example, the polar organic solvent may be used in an amount of 0.5 to 5 equivalents or 1 to 5 equivalents based on 1 equivalent of the dihalogenated aromatic compound.

The polymerization reaction may be carried out with agitation at 200 to 280 °C, 220 to 260 °C, or 240 to 260 °C, for example, and, if necessary, the reaction is carried out while stirring at 200 to 240 °C, and then the temperature is raised to 240 to 280 °C. can react.

The polymerization reaction may be carried out for 3 to 10 hours or 4 to 7 hours, for example.

The crystallization or precipitation in step b) may be carried out, for example, at 120 to 200 ° C. and 1 to 10 bar for 10 to 100 minutes, or at 130 to 160 ° C. and 1 to 3 bar for 10 to 30 minutes, and this range There is an effect of forming particles having excellent particle flowability and a narrow particle size distribution in the inside.

The filtering step c) may be performed, for example, in a filter or a centrifugal separator, and in this case, it is possible to easily separate liquid organic solvents, residual reactants, or other impurities from solid polymerization products.

The filter is not particularly limited if it is a filter commonly available in the art to which the present invention belongs, and may be, for example, a gravity filter or a vacuum filter.

The d) washing and dehydrating step includes, for example, a first washing and dehydrating step of washing and dehydrating the polymerization product with a washing solution, and a second washing and dehydration step of washing and dehydrating the polymerization product that has passed through the first washing and dehydration step again with a washing solution and dehydration. step, and in this case, it is possible to effectively remove salts (eg, salt), carboxylic acids, and oligomers produced as by-products.

The first washing liquid is preferably water having high salt solubility, and the second washing liquid may be, for example, water, acetone or ethanol. there is.

In the first washing and dehydration step, for example, washing with a washing solution at 15 to 30 ° C. or 20 to 25 ° C. for 50 to 80 minutes, 55 to 75 minutes, or 60 to 70 minutes, followed by centrifugation and dehydration, The second washing and dehydration step, for example, when water is used as the secondary washing liquid, is washed at 80 to 180 ° C. or 100 to 150 ° C. for 50 to 80 minutes, 55 to 75 minutes, or 60 to 70 minutes by pressure washing. After centrifugation, dehydration, and when acetone or ethanol is used as the secondary washing solution, washing by pressure washing at 50 to 100 ° C, or 80 to 100 ° C for 50 to 80 minutes, 55 to 75 minutes, or 60 to 70 minutes After that, it can be dehydrated by centrifugation, and in this case, the effect of removing salts, carboxylic acids, and oligomers produced as by-products is excellent.

It is obvious to those skilled in the art that the pressure during pressure washing in the present description is not separately limited as a dependent variable of the washing temperature and is adjusted according to the washing temperature.

The first and second washing and dehydration steps may be carried out, for example, one or more times, 1 to 5 times, 1 to 3 times, or 1 time each or in cycles, in which case salts and carboxylic acids produced as by-products may be performed. And the effect of removing oligomers is excellent.

The drying step e) may be, for example, drying at 100 to 180 ° C. or 110 to 170 ° C. for 1 to 6 hours or 2 to 4 hours, preferably vacuum drying, in which case residual washing liquid is completely removed. It works.

The vacuum drying may be, for example, drying under 0.05 to 0.5 bar and 0.05 to 0.3 bar, and there is an effect of completely removing residual washing liquid within this range.

The apparatus for producing polyphenylene sulfide of the present invention includes a reactor, a distillation column, a condenser, and a tank for collecting condensed dewatered liquid, wherein the distillation column includes a packing column, and the reactor includes a paddle-shaped stirrer and It includes a spiral baffle jacket, and a vacuum pump capable of reducing pressure during the reaction is installed in a vent line after the distillation column. In this case, energy efficiency, productivity, pipe corrosion resistance, quality stability, etc. are excellent, the device replacement cycle is extended, and there is an effect of reducing fouling in the device.

The vacuum pump may be preferably installed in the upper vent line of the dehydration tank, and in this case, energy efficiency, productivity, pipe corrosion resistance and quality stability are excellent, the device replacement cycle is extended, and fouling in the device is reduced. This little effect.

A method and apparatus for producing polyphenylene sulfide according to the present invention will be described with reference to FIGS. 1 to 3. These drawings are only schematic diagrams illustrating the present invention and not limited to the depicted embodiments, depicting only the necessary means for explaining the present invention for ease of understanding, and other obvious means necessary for carrying out the method and apparatus omitted from the drawing.

1 is a diagram schematically illustrating a dehydration reaction apparatus including a reactor, a distillation column, a condenser, and a dehydration liquid tank used in Comparative Examples 1 to 3, through a vent line at the upper end of the dehydration liquid tank to the atmosphere ( ATM) is connected. Exhaust gas discharged through the vent line may be treated by a conventional exhaust gas treatment method in the art to which the present invention pertains, and is not particularly limited.

2 is a diagram schematically showing a dehydration reaction apparatus including a reactor, a distillation column, a condenser, a dehydration liquid tank, and a pressure reducing device used in Examples 1 to 4.

Referring to FIG. 2, a paddle-type agitator composed of a shaft and a propellant is installed inside the reactor, but a drive or motor connected to the shaft is omitted from the drawing. The raw material for the dehydration reaction is supplied through a raw material supply pipe to the top of the reactor, and the outer wall of the reactor is covered with a spiral baffle jacket, through which high-temperature thermal oil circulates to supply heat to the reactor. A distillation column is installed at the top of the reactor, and the distillation column refluxes the polar solvent introduced into the reactor during the reaction. For reference, reflux in the reflux ratio of the present description means that the condensed liquid of the gas passing through the top of the distillation column is introduced back to the top of the distillation column without sending it to the dehydration tank. In the drawing, double-headed arrows indicate the entry and exit of polar solvent, and the actual distillation column may be directly connected to a vent hole formed at the top of the reactor. As another example, the top of the reactor and the bottom of the distillation tower may be designed to communicate with the first vent line, that is, a connecting pipe. The installation method of the distillation tower in the reactor is not particularly limited if it is a conventional installation method in the technical field to which the present invention belongs.

The exhaust gas discharged from the top of the distillation column is transferred to the condenser through the second vent line, and the condensate (dehydration liquid) condensed through the condenser is transferred to the dehydration liquid tank through the third vent line. At this time, some of the condensate (dehydration liquid) is recovered to the top of the distillation column. The condensate is mostly water and may be referred to as dehydration. As described above, whether to terminate the reaction may be determined according to the amount of dehydration liquid filled in the dehydration liquid tank. A vacuum device is connected to a fourth vent line extending from the rear end of the dewatering liquid to form a vacuum system. Although not shown in FIG. 2 , a pressure sensor may be installed on one side of the vent line if necessary. As described above, when polyphenylene sulfide is produced by the polyphenylene sulfide manufacturing apparatus described in FIG. 2, energy consumption is low and heat transfer is efficient, so that batch time is reduced and productivity is improved, and the loss of polar organic solvent in the dehydration solution is reduced. Pipe corrosion is minimized and the generation of by-products such as hydrogen sulfide is minimized, and furthermore, the equipment replacement cycle is extended and sulfur loss does not occur, making it easy to manage the physical properties of polyphenylene sulfide resin during polymerization and the final product after polymerization. It has the advantage of less fouling generation.

For reference, although not shown in FIG. 2 below, after the dehydration reaction is completed, a dihalogenated aromatic compound and an organic solvent are introduced into the top of the reactor for polymerization, or the remaining mixture containing alkali metal sulfide remaining in the reactor after the dehydration reaction is finished Polyphenylene sulfide may be prepared by transferring the polyphenylene sulfide to a separately provided polymerization reactor, and then polymerization by introducing a dihalogenated aromatic compound and an organic solvent.

3 is an overall process diagram schematically showing dehydration (reaction), polymerization (reaction), crystallization, filter (filtration), washing and drying steps of polyphenylene sulfide according to the present disclosure.

Referring to FIG. 3, a mixture containing sulfide, alkali metal hydroxide, alkali metal carboxylate, polar organic solvent and water is used as a raw material for dehydration (reaction), and water is discharged as the dehydration reaction proceeds. After the dehydration reaction is completed, a dihalogenated aromatic compound and a polar organic solvent are added as raw materials to the alkali metal sulfide-containing mixture remaining in the reactor, polymerized (reacted) to produce a polymerization product, and then crystallized or precipitated by lowering the temperature. Thereafter, the crystallized or precipitated polymerization product is filtered through a filter to remove the solvent and the like, and the remaining crystals or precipitates are washed with water to remove salts and the like, and then dehydrated. At this time, water (washing liquid) containing salt, etc. is discharged to wastewater, and the dehydrated polymerization product is dried to remove volatile organic matter, and then obtained as a final product.

Hereinafter, preferred embodiments are presented to aid understanding of the present invention, but the following examples are merely illustrative of the present invention, and various changes and modifications are possible within the scope and spirit of the present invention. It is obvious to those skilled in the art, It goes without saying that these variations and modifications fall within the scope of the appended claims.

[Example]

Comparative Example 1

<Method for preparing sulfur source: dehydration reaction>

During the production process of polyphenylene sulfide, 180 kg of 32 wt% NaOH hydrate, 140 kg of 60 wt% NaSH hydrate, 46 kg of NaOAc, and 284 kg of NMP were introduced into a reactor as shown in FIG. It was heated from there to volatilize the water. At this time, a 1 m ³ reactor, a bottle-type stirrer, and a spiral baffle jacket were used, and 230° C. thermal oil was circulated through the jacket to heat the mixture in the reactor. A packing column (packing material: 5/8 inch Pall ring) with a height of about 1.5 m and a condenser were used to recover NMP from the vaporized gas at the top of the reactor, and the reflux ratio was maintained at about 0.5 during the reaction process. Cooling water was used for condensation in the condenser, and when 170 kg of dehydration liquid was obtained, the dehydration reaction was terminated to obtain a remaining mixture containing Na ₂ S.

<Method for producing polyphenylene sulfide: polycondensation reaction>

After the dehydration reaction was completed, 218 kg of para-dichlorobenzene (p-DCB) as a raw material for polycondensation and 210 kg of NMP as a solvent were additionally added to the reactor, heated to 235 ° C, and stirred for about 3 hours. Thereafter, after heating to 265 ℃ again, the polycondensation reaction was completed by stirring for about 2 hours. Immediately after completion of the reaction, the mixture was cooled to 140° C. for about 20 minutes to crystallize a polymerization product including salt, and a solid material was obtained using a filter. After putting water at room temperature into the obtained solid material, washing it for 60 minutes, dehydrating it using a centrifugal separator, putting water at 150 ℃ again and washing it under pressure for 60 minutes, and then dehydrating it using a centrifugal separator to remove salt, etc. Impurities were removed. Finally, the dehydrated polymerization product was vacuum dried at 150 °C to obtain a polyphenylene sulfide product.

Comparative Example 2

In Comparative Example 1, the same method as in Comparative Example 1 was carried out, except that the pressure of the reactor was maintained at an equal pressure of 0.5 bar during the dehydration reaction by using a vacuum pump at the rear end of the dehydration tank. At this time, the pressure control was performed using a pressure sensor.

Comparative Example 3

In Comparative Example 1, the same method as in Comparative Example 1 was carried out, except that the reactor pressure was maintained at an equal pressure of 0.2 bar during the dehydration reaction using a vacuum pump at the rear end of the dehydration tank. At this time, the pressure control was performed using a pressure sensor.

Example 1

In Comparative Example 1, except that the pressure of the reactor was reduced at a rate of 0.0024 bar / min at a rate of 0.0024 bar / min by using a vacuum pump at the rear end of the dehydration tank to reduce the pressure of the reactor at normal pressure so that the pressure at the end of the reaction was 0.7 bar. It was carried out in the same way as in Comparative Example 1. At this time, the pressure control was performed using a pressure sensor.

Example 2

In Comparative Example 1, by using a vacuum pump at the rear end of the dehydration tank, the reactor pressure was started at atmospheric pressure during the reaction, and when dehydration started, the pressure was reduced at a rate of 0.0050 bar/min so that the pressure at the end of the reaction was 0.4 bar. Except for the above, it was carried out in the same manner as in Comparative Example 1. At this time, the pressure control was performed using a pressure sensor.

Example 3

In Comparative Example 1, by using a vacuum pump at the rear end of the dehydration tank, the reactor pressure was started at normal pressure during the reaction, and when dehydration started, the pressure was reduced at a rate of 0.0083 bar/min so that the pressure at the end of the reaction was 0.1 bar. Except for the above, it was carried out in the same manner as in Comparative Example 1. At this time, the pressure control was performed using a pressure sensor.

Example 4

In Comparative Example 1, by using a vacuum pump at the rear of the dehydration tank, the reactor pressure was started at normal pressure during the reaction, and when dehydration started, the pressure was reduced at a rate of 0.0094 bar/min so that the pressure at the end of the reaction was 0.04 bar. Except for the above, it was carried out in the same manner as in Comparative Example 1. At this time, the pressure control was performed using a pressure sensor.

[Test Example]

The results of the dehydration and polycondensation reactions performed in Comparative Examples 1 to 3 and Examples 1 to 4 were measured by the following method, and the values are shown in Table 1 below.

* NMP composition (wt%): measured using G/C (gas chromatography) analysis method.

* Fouling: After completion of the reaction, the inside of the reactor was visually checked, and when fouling occurred, it was evaluated as 'yes', and when it did not occur, it was evaluated as 'no'.

* Pipe contamination degree: After completion of the reaction, the pipe was visually checked, and when it was dark yellowish brown, it was evaluated as 'bad', when it was light yellow, it was evaluated as 'normal', and when the pipe was clean as before the reaction, it was evaluated as 'none'.

Classification Reactor pressure (bar) Dehydration start temperature (℃) Dehydration end temperature (℃) NMP composition (wt%) Response time (hr) fouling Pipe pollution degree Comparative Example 1 (isobaric) 1.0 134 202 0.5 2.9 doesn't exist bad Comparative Example 2 (isobaric) 0.5 116 179 0.4 2.3 has exist bad Comparative Example 3 (isobaric) 1.0 94 153 0.3 1.7 has exist commonly Example 1 (Decompression) 1.0→0.7 134 188 0.3 2.1 doesn't exist bad Example 2 (decompression) 1.0→0.4 134 168 0.3 2.0 doesn't exist commonly Example 3 (Decompression) 1.0→0.1 134 133 0.2 1.8 doesn't exist doesn't exist Example 4 (decompression) 1.0→0.04 126 112 0.2 1.7 has exist doesn't exist

As shown in Table 1, the lower the reaction pressure in the production of polyphenylene sulfide, the lower the dehydration start temperature and the lower the dehydration end temperature, so that the temperature difference between the thermal oil flowing into the jacket and the mixture in the reactor increases, increasing the heat transfer efficiency. It was confirmed through the shortening of the reaction time. This reaction time, that is, the batch time, was reduced by up to about 40% or more under reduced pressure conditions. For reference, when the reaction pressure is less than 0.1 bar, as the condensation temperature is lowered to about 40 ° C or less, it becomes difficult to condense with general cooling water, and a separate cooling system may be required, which causes an increase in investment cost and energy consumption. .

In Comparative Example 1 and Comparative Example 2, pipe contamination was severe, and in Example 3, pipe contamination was not found. When the reaction temperature increases, volatile sulfur compounds such as H ₂ S increase, which increases the corrosiveness of the device. In addition, an increase in the amount of H ₂ S generated causes an increase in downstream facilities such as scrubbers and incinerators. In addition, H ₂ S is a toxic substance with a low boiling point and high volatility. It is difficult to determine the amount of gas loss, but the amount can be estimated through pipe corrosion. In conclusion, corrosiveness tends to increase exponentially with reaction temperature and intensifies above about 150 °C. In particular, in the case of Comparative Example 3, SMAB (Sodium-4-(N-methylamino)-butanoate) was not formed stably due to the initial salt precipitation, so that the number average molecular weight (Mn) of 3,000 g/mol or less during the condensation polymerization reaction after the dehydration reaction A large amount of low molecular weight polyphenylene sulfide was obtained. If the dehydration reaction proceeds at too low a temperature, the solubility in the reaction system is rapidly lowered and salts are precipitated, causing fouling in the reactor and adversely affecting the formation of SMAB. Therefore, a dehydration reaction temperature of 100 ° C or higher is required, and more stable solubility and SMAB formation can be induced at 120 ° C or higher.

In addition, in the case of Example 4, although not severe, problems similar to those of Comparative Example 3 were obtained during the polycondensation reaction due to salt precipitation in the late stage of the reaction, and low molecular weight polyphenylene sulfide having a number average molecular weight (Mn) of 5,000 g/mol or less was obtained. It became. However, Example 4, unlike Comparative Example 3, had the lowest NMP composition and no pipe contamination occurred.

In Examples 1 to 3, in which gradual pressure reduction was applied during the dehydration reaction, the NMP composition in the dehydration solution was reduced under the same distillation column operating conditions compared to Comparative Examples 1 to 3 to which isostatic pressure was applied, resulting in less NMP loss and reduced fouling. The NMP composition in the dewatering liquid was the lowest and no fouling was found.

Looking again at Example 3, the dehydration reaction was carried out by starting at normal pressure at the beginning of the dehydration reaction and reducing the pressure to 0.1 bar, and the temperature was maintained at 130 to 135 ° C throughout the dehydration reaction. As a result, the reaction time was short, Device corrosion was the least, and NMP loss in the dewatering liquid was also the least. In addition, no fouling was found in the reactor, and it was confirmed that high molecular weight polyphenylene sulfide having a number average molecular weight (Mn) of 25,000 g/mol or more was produced during the condensation polymerization reaction after the dehydration reaction.

Claims (15)

A reactor comprising a paddle-type agitator and a spiral baffle jacket; distillation column; condenser; and a tank for collecting the condensed dehydration liquid; a mixture including sulfide, alkali metal hydroxide, alkali metal carboxylate, polar organic solvent, and water is introduced into the reactor of the dehydration reaction device, and the inside of the reactor is dehydrated. Including the step of dehydration by operating under temperature conditions and dehydration pressure conditions,
The reactor is operated under a dehydration temperature condition of 100 to 130 ° C. lower than the polymerization temperature of polyphenylene sulfide and a dehydration pressure condition lower than the polymerization pressure of polyphenylene sulfide,
Characterized in that the dehydration reaction is terminated when 70 to 90% by weight of the total amount of water that can be vaporized after the dehydration reaction is collected in the dehydration tank
Method for producing polyphenylene sulfide. delete According to claim 1,
Characterized in that the distillation column is a packing column
Method for producing polyphenylene sulfide. According to claim 3,
The packing column is from the group consisting of a Raschig ring, a Pall ring, a CMR ring, an IMTP ring, a Berl saddle and a Metal Hypac Characterized in that the packing column filled with one or more selected packing materials
Method for producing polyphenylene sulfide. According to claim 1,
Characterized in that some of the dehydrated liquid condensed in the condenser is recovered to the distillation column
Method for producing polyphenylene sulfide. According to claim 1,
The dehydration reaction device is characterized in that it comprises a pressure reducing device
Method for producing polyphenylene sulfide. According to claim 6,
Characterized in that the pressure reducing device is installed in the vent line leading to the top of the distillation column
Method for producing polyphenylene sulfide. According to claim 1,
The sulfide is characterized in that at least one selected from the group consisting of alkali metal bisulfate, alkali metal hydrosulfide and alkali metal sulfide
Method for producing polyphenylene sulfide. According to claim 1,
Characterized in that the alkali metal carboxylate is at least one selected from the group consisting of alkali metal acetate, alkali metal hexanoate and alkali metal benzoate.
Method for producing polyphenylene sulfide. According to claim 1,
The polar organic solvent is alcohol, alkylene oxide, hexamethylphosphoramide, tetramethylurea, N,N'-ethylenedipyrrolidone, N-methyl-2-pyrrolidone, pyrrolidone, caprolactam, N- Characterized in that at least one selected from the group consisting of ethyl caprolactam, sulfolane, N, N'-dimethylacetamide and 1,3-dimethyl-2-imidazolidinone
Method for producing polyphenylene sulfide. According to claim 1,
The mixture comprises 1 equivalent of sulfide, 0.5 to 2 equivalents of alkali metal hydroxide, 0.01 to 1.5 equivalents of alkali metal carboxylate, 1 to 5 equivalents of polar organic solvent and 1 to 15 equivalents of water.
Method for producing polyphenylene sulfide. According to claim 1,
Characterized in that the reflux ratio of the distillation column and the condenser is 0.3 to 0.7
Method for producing polyphenylene sulfide. According to claim 1,
Characterized in that the dehydration pressure condition is a stepwise, gradual or continuous pressure reduction condition from normal pressure to 0.8 to 0.04 bar
Method for producing polyphenylene sulfide. According to claim 1,
The dehydration temperature condition is characterized in that the dehydration reaction starts at 112 to 134 ℃
Method for producing polyphenylene sulfide. A dehydration reaction apparatus used in the method for producing polyphenylene sulfide of claim 1 and including a reactor, a distillation tower, a condenser, and a tank for collecting condensed dehydration liquid,
The distillation column includes a packing column, and the reactor includes a paddle-shaped stirrer and a spiral baffle jacket, and the dehydration temperature condition lower than the polymerization temperature of polyphenylene sulfide and the dehydration pressure lower than the polymerization pressure of polyphenylene sulfide It is operated under pressure conditions, and a vacuum pump capable of reducing pressure during the reaction is installed in the vent line of the distillation column, and includes a pressure sensor for adjusting the dehydration pressure condition.
Manufacturing equipment for polyphenylene sulfide.

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