KR20220026727A - Method for preparing polymer - Google Patents

Abstract

The present invention relates to a preparation method of a polymer which comprises: a step of supplying a raw material stream and a solvent stream to a reactor to produce a reaction product; a step of supplying a first stream of a reactor effluent stream to a devolatilizer to separate a top effluent stream comprising a solvent and a bottom effluent stream comprising the polymer; a step of supplying a mixed stream of a second stream of the reactor effluent stream and a devolatilizer bottom effluent stream to a stripper; and a step of separating the top effluent stream comprising the solvent in the stripper and separating the bottom effluent stream comprising the polymer.

Description

Polymer manufacturing method {METHOD FOR PREPARING POLYMER}

The present invention relates to a method for producing a polymer, and more particularly, to a method for preparing a reaction product including a polymer, and effectively separating and reusing a solvent from the reaction product.

As a method of polymerizing the polymer, methods such as suspension polymerization, emulsion polymerization, superficial polymerization, and solution polymerization are used. However, each of the above polymerization methods has the following problems, respectively.

For example, in the case of manufacturing by bulk polymerization, the viscosity of the reactant rapidly rises as the reaction proceeds, causing an increase in mechanical load, and furthermore, it is difficult to control the reaction temperature during polymerization, so commercial mass production is difficult. There is this.

Further, in the case of suspension polymerization, an initiator (catalyst) is dissolved in a monomer, the monomer is dispersed in water, and then a dispersant is incorporated to stabilize the suspension formed. In all suspension polymerization methods, a surfactant is used to disperse the monomer particles so that the polymer does not fuse and agglomerate during the reaction, and various dispersants such as water-insoluble particulate inorganic materials and organic materials are used depending on the monomer to be polymerized. It has the disadvantage of being lowered.

Therefore, in order to mass-produce a polymer, a solution polymerization method using a continuous polymerization reactor has been mainly used.

As such, when a reaction product including a polymer is manufactured through a solution polymerization method, the amount of solvent compared to the raw material is large, so it is important in terms of cost reduction to recover and reuse the solvent from the reaction product.

In contrast, conventionally, a steam stripping method and a direct volatilization method have been used to recover the solvent from the reaction product.

Specifically, in the steam stripping method, the reaction product is mixed with hot water, a large amount of steam is supplied to volatilize the solvent together with water vapor to recover the solvent, and the polymer crumb is separated and water is passed through the extrusion process. It may be a method of finally obtaining a polymer after removing and residual solvent. In this case, there is a problem in that energy consumption is very high due to the use of a large amount of steam, and since the recovered solvent contains water, there is a problem that a separate purification process is required. There was an impossible problem.

In addition, the direct volatilization method includes a method of recovering the solvent by supplying heat required for evaporation of the solvent through indirect heat exchange of the reaction product through a heat exchanger, and a method of recovering the solvent by directly transferring mechanical energy in the form of frictional heat. . In the direct volatilization method using the heat exchanger, as the viscosity of the reaction product solution increases, the heat exchange efficiency decreases, making it difficult to recover the solvent. .

KR 1633076 B

The problem to be solved in the present invention is to prepare a high-purity polymer with a low content of impurities in effectively recovering and reusing a solvent in order to solve the problems mentioned in the technology that is the background of the invention, and to reduce energy consumption to provide a way to

According to an embodiment of the present invention for solving the above problems, the present invention comprises the steps of supplying a raw material stream and a solvent stream to a reactor to prepare a reaction product; feeding a first stream of the reactor effluent stream to a devolatilizer to separate a top effluent stream comprising solvent and a bottoms effluent stream comprising polymer; feeding a second stream of the reactor effluent stream and a mixed stream of the devolatilizer bottoms effluent stream to a stripper; and separating an overhead effluent stream comprising solvent in the stripper and separating a bottom effluent stream comprising polymer.

According to the method for producing a polymer of the present invention, a high-purity polymer with reduced impurity content can be produced while reducing energy consumption in preparing a reaction product including a polymer, recovering a solvent from the reaction product and reusing it.

1 is a process flow diagram of a polymer manufacturing method according to an embodiment of the present invention.
2 is a process flow diagram of a method for preparing a polymer according to a comparative example.

The terms or words used in the description and claims of the present invention should not be construed as being limited to their ordinary or dictionary meanings, and the inventor must properly understand the concept of the term in order to best describe his invention. Based on the principle that can be defined, it should be interpreted as meaning and concept consistent with the technical idea of the present invention.

In the present invention, the term 'stream' may mean a flow of a fluid in a process, and may also mean a fluid itself flowing in a pipe. Specifically, the 'stream' may mean both the fluid itself and the flow of the fluid flowing within a pipe connecting each device. In addition, the fluid may refer to a gas or a liquid.

In the present invention, the term 'crumb' is generated in the steam stripping process, and may refer to a polymer in the form of droplets removed by volatilizing a solvent and impurities together with steam (water vapor) from the reaction product.

Hereinafter, the present invention will be described in more detail with reference to FIG. 1 to help the understanding of the present invention.

According to the present invention, a method for preparing a polymer is provided. In the method for preparing the polymer, supplying a raw material stream and a solvent stream to the reactor 100 to prepare a reaction product; feeding a first stream of the reactor (100) effluent stream to a devolatilizer (200) to separate an overhead effluent stream comprising solvent and a bottom effluent stream comprising polymer; feeding a second stream of the reactor 100 effluent stream and a mixed stream of the devolatilizer 200 bottom effluent stream to a stripper 300; and separating the overhead effluent stream including the solvent from the stripper 300 and separating the bottom effluent stream including the polymer.

According to an embodiment of the present invention, the reaction product is generated by supplying a monomer stream and a solvent stream to the reactor 100 for a polymerization reaction, and the reaction product may include a polymer and a solvent. In addition, the reaction product may further include impurities such as unreacted monomers.

For example, the reaction product is produced by a polymerization reaction by supplying a solvent stream, a stream containing an aromatic vinylic monomer, and a stream containing a conjugated diene-based monomer to the reactor 100, and an aromatic vinyl-based monomer-derived unit and It may include a copolymer and a solvent including a unit derived from a conjugated diene-based monomer. In addition, the reaction product may further include unreacted aromatic vinyl-based monomers and unreacted conjugated diene-based monomers as impurities.

The polymer is not particularly limited as long as it includes an aromatic vinyl-based monomer-derived unit and a conjugated diene-based monomer-derived unit. For example, the polymer may be a synthetic rubber comprising at least one selected from the group consisting of Styrene-Butadiene Rubber (SBR) and Solution Styrene-Butadiene Rubber (SSBR). .

The conjugated diene-based monomer is, for example, 1,3-butadiene, 2,3-dimethyl-1,3-butadiene, piperylene, 3-butyl-1,3-octadiene, isoprene, 2-phenyl-1, It may include one or more selected from the group consisting of 3-butadiene and 2-halo-1,3-butadiene (halo means a halogen atom). More specifically, in the present invention, the conjugated diene-based monomer may include 1,3-butadiene.

In addition, the aromatic vinyl-based monomer is, for example, styrene, α-methylstyrene, 3-methylstyrene, 4-methylstyrene, 4-propylstyrene, 1-vinylnaphthalene, 4-cyclohexylstyrene, 4-(p- It may include at least one selected from the group consisting of methylphenyl)styrene and 1-vinyl-5-hexylnaphthalene. More specifically, in the present invention, the aromatic vinyl-based monomer may include styrene.

In addition, the solvent may include a hydrocarbon-based solvent. For example, the hydrocarbon-based solvent may include an aliphatic hydrocarbon-based solvent and an alicyclic hydrocarbon, and the aliphatic hydrocarbon-based solvent is one selected from the group consisting of butane, pentane, hexane, isopentane, heptane, octane and isooctane. The above may be included, and the alicyclic hydrocarbon-based solvent may include at least one selected from the group consisting of cyclopentane, methylcyclopentane, cyclohexane, methylcyclohexane, and ethylcyclohexane. More specifically, in the present invention, the solvent may include n-hexane.

The at least one synthetic rubber selected from the group consisting of Styrene-Butadiene Rubber (SBR) and Solution Styrene-Butadiene Rubber (SSBR) is prepared by solution polymerization or emulsion polymerization. (Emulsion Polymerization) can be produced by continuous polymerization.

As described above, the reaction product generated in the process of producing a polymer through the solution polymerization reaction contains a solvent and impurities along with the polymer. In the present invention, the solvent is effectively recovered and reused from the reaction product, and the content of impurities in the polymer To provide a method to minimize

According to an embodiment of the present invention, a purification step may be performed to separate the solvent from the reaction product. For example, the reactor 100 discharge stream containing the reaction product may be separated into a stream containing a solvent and a stream containing a polymer while passing through the devolatilization unit 200 and the stripper 300 .

The reactor 100 discharge stream is branched into a first stream and a second stream, the first stream is supplied to the devolatilization unit 200, the second stream may be supplied to a stripper 300 to be described later. . At this time, the flow ratio of the first stream and the second stream of the branched reactor 100 discharge stream may be 20:80 to 80:20, 50:50 to 80:20, or 70:30 to 80:20. The first stream and the second stream of the reactor 100 effluent stream are branched in the above ratio, the first stream is fed to the devolatilizer 200, and the second stream is the devolatilizer 200 bottom By mixing with the discharge stream and supplying it to the stripper 300, the solvent recovery through the devolatilizer and energy cost reduction effect through the stripper can be obtained at the same time by controlling the content of the polymer in the mixed stream.

The reactor 100 effluent stream may be stored in a reaction product storage tank prior to branching into a first stream and a second stream. The reactor 100 discharge stream stored in the storage tank is discharged from the storage tank while controlling a flow rate, and the reactor 100 discharge stream discharged from the storage tank may be branched into a first stream and a second stream.

The content of the polymer in the reactor 100 effluent stream is from 15% to 30% by weight, from 15% to 25% by weight or from 20% to 25% by weight, and the content of the solvent is from 70% to 85% by weight, 70 weight % to 80 weight % or 75 weight % to 80 weight %. A first stream of the reactor 100 effluent stream comprising a polymer and a solvent in an amount within the above range is supplied to the devolatilization unit 200, and in the devolatilization unit 200, a second stream of the reactor 100 effluent stream is produced. From one stream it can be separated into a top draw stream comprising solvent and a bottom draw stream comprising polymer.

The operating temperature and operating pressure of the devolatilization apparatus 200 may be controlled in order to effectively separate the solvent and the polymer. For example, the operating temperature of the devolatilization device 200 may be 70 °C to 130 °C, 90 °C to 130 °C, or 90 °C to 110 °C. By operating the devolatilizer 200 within the above range, the polymer in the devolatilizer 200 overhead effluent stream may not be present, and the content of solvents and impurities in the bottom effluent stream may be minimized.

In the devolatilization apparatus 200, the solvent in the first stream of the reactor 100 discharge stream may be volatilized by transferring mechanical energy in the form of frictional heat. Specifically, the devolatilization device 200 is an extruder type device, and includes a cylindrical body and a screw stirring system that transfers mechanical rotational energy to the solution in the devolatilization device 200 in the form of heat by friction. can do.

Conventionally, a steam stripping method and a direct volatilization method have been used to recover the solvent from the reaction product.

Specifically, in the steam stripping method, the reaction product is mixed with hot water, a large amount of steam is supplied to volatilize the solvent together with water vapor to recover the solvent, and the polymer crumb is separated and water is passed through the extrusion process. It may be a method of finally obtaining a polymer after removing and residual solvent. In this case, there is a problem in that energy consumption is very high due to the use of a large amount of steam, a separate purification process is required because the recovered solvent contains water, and when the content of the polymer in the reaction product is too high, high concentration It is difficult to control the size of the crumb due to the viscosity of the crumb, and as a result, the solvent and impurities remaining in the crumb are not easily evaporated, thereby increasing the amount of the remaining solvent in the crumb. In this case, the solvent and impurities remaining in the crumb may be discharged to the atmosphere together with water vapor in the dehydration step to be described later, which has problems in health and environmental toxicity of workers.

In addition, the direct volatilization method includes a method of recovering the solvent by supplying heat required for evaporation of the solvent through indirect heat exchange of the reaction product through a heat exchanger, and a method of recovering the solvent by directly transferring mechanical energy in the form of frictional heat. . In the direct volatilization method using the heat exchanger, as the viscosity of the reaction product solution increases, the heat exchange efficiency decreases, making it difficult to recover the solvent. .

In contrast, in the present invention, the solvent in the first stream of the reactor 100 discharge stream is volatilized by transferring mechanical energy in the form of frictional heat, and the solvent that is not separated in the devolatilization device 200 is a stripper 300 to be described later. By further separating using

The devolatilization unit 200 top discharge stream passes through the first condenser 400 and is supplied to the condensing solvent tank 500, and the bottom discharge stream including the liquid solvent in the condensing solvent tank 500 is converted into a reactor. (100) may be refluxed. Specifically, unlike the steam stripping method, the devolatilization device 200 mixes the reaction product with water and is not a solvent evaporation system through steam supply. May not contain water. Therefore, the devolatilization device 200 upper discharge stream can be condensed using the first condenser 400 and supplied to the condensing solvent tank 500 to be separated into a gaseous phase and a liquid phase, and the liquid phase contains impurities As a solvent that is not used, it is discharged as a discharge stream at the bottom of the condensed solvent tank 500 without a separate purification process, and can be directly supplied to the reactor 100 and reused. At this time, the first condenser 400 may condense 80% to 95% of the supplied devolatilization device 200 upper exhaust stream. Due to this, as the flow rate supplied to the stripper 300 and the purification column 600 at the rear end of the devolatilization device 200 decreases, the energy consumption may be reduced.

The discharge stream from the bottom of the condensed solvent tank 500 including the solvent may be supplied to and stored in the solvent tank, and the solvent may be supplied to the reactor 100 while controlling the flow rate in the solvent tank.

Impurities not condensed in the first condenser 400 may be supplied to the purification column 600 through the second condenser 410 as a gaseous top discharge stream from the condensing solvent tank 500 . Specifically, the gas phase separated in the condensing solvent tank 500 contains a large amount of impurities, and is condensed using the second condenser 410 and supplied to the purification column 600 to separate the solvent and impurities. .

The content of the polymer in the devolatilizer 200 bottoms outlet stream may be 80 wt% or more, 80 wt% to 95 wt%, or 85 wt% to 95 wt%. As such, the devolatilization device 200 transfers mechanical thermal energy in the form of frictional heat to volatilize the solvent in the first stream of the reactor 100 discharge stream, so that the content of the polymer in the lower discharge stream is 80 wt% to By operating to the extent of containing 95% by weight, it is possible to separate a large amount of solvent in the reaction product with little energy without flowing out of the polymer into the overhead stream.

The operation of the devolatilization device 200 is affected by variables such as the viscosity and delivery area of the supplied stream. Specifically, when the concentration of the polymer in the devolatilization device 200 is lowered, the viscosity of the solution is lowered, and thus the size of the device increases, thereby increasing the device cost. Accordingly, in the present invention, the above problem is solved by controlling the concentration concentration of the polymer in the devolatilization unit 200, that is, the content of the polymer in the discharge stream below the devolatilization unit 200 to 80% by weight or more. In addition, even if the concentration of the polymer in the devolatilization unit 200 is increased to the above range, the polymer is mixed with the second stream of the reactor 100 discharge stream before feeding to the stripper 300 at the rear stage to form a mixed stream. Operation in the stripper 300 was facilitated by lowering the concentration of the.

However, in the prior art, as in the present invention, when using the devolatilization device 200 and the stripper 300 to separate the solvent and impurities in the reaction product, in order to enable operation in the stripper 300, devolatilization It was necessary to lower the concentration concentration in the device 200, and in this case, the size of the devolatilization device 200 increases and the device cost increases, and at the same time, the flow rate of the stream fed to the stripper 300 and the purification column 600 ), there is a problem in that energy consumption increases due to an increase in the flow rate flowing into it.

The devolatilization unit 200 bottom discharge stream is a stream containing a polymer in an amount of 80 wt% to 95 wt%, and when the solvent is separated by a steam stripping method by supplying it to the stripper 300, as described above Due to the high concentration and viscosity, it is difficult to control the size of the crumb, which makes it difficult to remove the solvent remaining in the crumb, which may make operation difficult. In contrast, in the present invention, a mixed stream is formed by mixing the devolatilization unit 200 lower discharge stream and a second stream branched from the reactor 100 discharge stream, and the mixed stream can be supplied to the stripper 300 . there is. Specifically, the devolatilization unit 200 bottoms outlet stream having a polymer content of 80 wt% to 95 wt% and a second stream of the reactor 100 outlet stream having a polymer content of 15 wt% to 30 wt% By mixing, the content of the polymer in the mixed stream may be lowered to a range where the operation of the stripper 300 is possible. For example, the content of the polymer in the mixed stream may be 30% to 60% by weight, 40% to 60% by weight or 50% to 60% by weight. Through this, it is possible to improve the flowability of transferring the discharge stream at the bottom of the devolatilization device 200, which is high in viscosity due to the high polymer content, to the stripper 300, and at the same time enables the operation of the stripper 300 to remove the polymer. It can be isolated with high purity.

According to an embodiment of the present invention, the mixed stream is supplied to the stripper 300, and by effectively separating the solvent and impurities in the mixed stream in the stripper 300, a polymer of high purity can be obtained.

The mixed stream may be mixed with water before being fed to the stripper 300 . The flow ratio of the mixed stream and water may be 1:1 to 1:4, 1:1.5 to 1:3, or 1:1.5 to 1:2.5. By mixing the mixed stream and water within the above range and supplying it to the stripper 300, the size of the crumb can be controlled by preventing the crumbs from agglomeration through dispersion between the crumbs in the mixed stream, and through this, it is included in the mixed stream By allowing the unreacted monomer and solvent to be easily evaporated, it is possible to obtain the effect of reducing energy consumed for solvent recovery while maintaining the stripping effect.

The water mixed with the reaction product may be at a high temperature. For example, the temperature of the water may be 60 °C to 95 °C, 70 °C to 95 °C, or 85 °C to 95 °C. By supplying the stripper 300 by mixing water having a temperature within the above range with the mixed stream, there is an effect of improving the solvent recovery performance in the stripper.

In the stripper 300, the operating temperature and operating pressure can be controlled in order to effectively separate the polymer and components other than the polymer from the mixed stream, for example, the solvent and impurities that are not separated in the devolatilization apparatus 200. there is. For example, the operating temperature of the stripper 300 may be 95 °C to 110 °C, 95 °C to 105 °C or 100 °C to 105 °C. In addition, the operating pressure of the stripper 300 may be 0.1 barg to 1 barg, 0.3 barg to 0.8 barg or 0.5 barg to 0.8 barg.

Steam may be supplied to the lower portion of the stripper 300, and by supplying steam to a mixed stream mixed with water supplied to the stripper 300, the solvent and impurities are separated by volatilization with water vapor to separate the upper discharge stream. can be discharged

Since the stripper 300 top discharge stream contains water along with a solvent and impurities, it may be sent to the purification column 600 to undergo a purification process.

The stripper 300 bottoms outlet stream may be discharged in the form of polymer crumbs comprising water and a high content of polymer. At this time, the content of the solvent and impurities in the stripper 300 lower discharge stream may be 1 wt% or less, 0.01 wt% to 1 wt%, or 0.1 wt% to 1 wt%.

The stripper 300 bottom discharge stream is discharged to include water and a high content of polymer, and may further include the step of dehydrating the stripper 300 bottom discharge stream. Specifically, the stripper 300 lower discharge stream is removed by evaporating water to water vapor through a dehydration step through heating, and a polymer of high purity can be obtained.

In the dehydration step, the solvent and impurities remaining in the polymer crumb may be discharged to the atmosphere together with water vapor. In this case, there were problems of worker health and environmental toxicity. In contrast, in the present invention, by using the devolatilization device 200 and the stripper 300 to minimize the content of solvent and impurities in the polymer crumb, that is, the stripper 300 lower discharge stream, it is discharged together with water vapor in the dehydration step. The content of solvents and impurities was minimized, thereby improving the working environment.

The condensing solvent tank 500 top discharge stream and the stripper 300 top discharge stream may be supplied to the purification column 600 to undergo a purification process. For example, the condensing solvent tank 500 top discharge stream and the stripper 300 top discharge stream may be joined in one line, or may be supplied to the stripper 300 in each line.

In the purification column 600 , an operating temperature and operating pressure may be controlled in order to separate a solvent, impurities, and water. For example, the operating temperature of the purification column 600 may be 40 °C to 140 °C, 45 °C to 130 °C, or 45 °C to 120 °C. In addition, the operating pressure of the purification column 600 may be 3 barg to 4.5 barg, 3 barg to 4 barg, or 3.5 barg to 4 barg.

The purification column 600 may separate the feed stream into a bottom discharge stream containing a solvent and an overhead discharge stream containing impurities and water. At this time, the purification column 600 bottom discharge stream containing the solvent may be supplied to the reactor 100 and reused. In addition, the bottom discharge stream of the purification column 600 may be supplied to and stored in a solvent tank, and the solvent may be supplied to the reactor 100 while controlling a flow rate in the solvent tank.

According to an embodiment of the present invention, in the polymer manufacturing method, if necessary, equipment such as a separation column, a condenser, a reboiler, a pump, a compressor, a mixing device and a separation device may be additionally installed.

As mentioned above, although the method for producing a polymer according to the present invention has been shown in the description and drawings, the drawings and the description above describe and show only the essential components for understanding the present invention, and the process shown in the description and drawings and In addition to the apparatus, processes and apparatus not separately described and not shown may be appropriately applied and used for carrying out the polymer production method according to the present invention.

Hereinafter, the present invention will be described in more detail by way of Examples. However, the following examples are intended to illustrate the present invention, and it is apparent to those skilled in the art that various changes and modifications can be made within the scope and spirit of the present invention, and the scope of the present invention is not limited thereto.

Example

Example 1

With respect to the process flow diagram shown in FIG. 1, the process was simulated using Aspen Plus Simulator of Aspen Tech.

Specifically, a reaction product including a styrene-butadiene copolymer as a polymer was prepared by supplying a styrene monomer and a 1,3-butadiene monomer as a monomer to the reactor 100, and supplying n-hexane as a solvent for a polymerization reaction. .

The reactor 100 effluent stream was branched into a first stream and a second stream, and the first stream was fed to the devolatilizer 200 . At this time, the content of the polymer in the exhaust stream of the reactor 100 was confirmed to be 25% by weight.

In the devolatilization device 200, mechanical energy is transferred in the form of frictional heat to volatilize the solvent in the first stream of the reactor 100 discharge stream and discharged as a top discharge stream, and the bottom discharge stream is discharged from the reactor 100 Mixed with a second stream of the stream to form a mixed stream and then fed to stripper 300 . At this time, the devolatilization device 200 was operated at a temperature of 90 ℃, the content of the polymer in the discharge stream lower than the devolatilization device 200 was confirmed to be 90% by weight. In addition, the first stream and the second stream of the reactor 100 effluent stream are separated at a flow ratio of 20:80, and the second stream of the reactor 100 effluent stream is separated from the devolatilizer 200 bottom effluent stream. and to control the content of the polymer in the mixed stream to 30% by weight.

The devolatilization unit 200 top discharge stream is 95% condensed through the first condenser 400 and then supplied to the condensing solvent tank 500, and separated into gaseous and liquid phases in the condensing solvent tank 500.

In the condensed solvent tank 500 , the liquid phase contains the solvent, discharged as a bottom discharge stream, refluxed to the reactor 100 and immediately reused, and the top discharge stream containing the gas phase passes through the second condenser 410 . After condensing, it was transferred to a purification column (600).

The mixed stream is mixed with water and supplied to the stripper 300, and the solvent and water are evaporated using hot steam in the stripper 300 and transferred to the purification column 600 as a top discharge stream, and the polymer and water The bottom discharge stream containing

In the purification column 600 , gaseous impurities and liquid solvent were separated, and the solvent was discharged as a bottom discharge stream of the purification column 600 , and was refluxed to the reactor 100 for reuse.

As a result, the flow rate and steam usage supplied to the stripper 300 and the flow rate and steam usage supplied to the purification column 600 were measured and shown in Table 1 below.

Example 2

In Example 1, the first stream and the second stream of the reactor 100 effluent stream are separated at a flow ratio of 50:50, and the second stream of the reactor 100 effluent stream is separated from the devolatilizer 200 ) was mixed with the bottom discharge stream, and the same method as in Example 1 was performed except that the content of the polymer in the mixed stream was controlled to 40 wt%.

As a result, the flow rate and steam usage supplied to the stripper 300 and the flow rate and steam usage supplied to the purification column 600 were measured and shown in Table 1 below.

Example 3

In Example 1, the first stream and the second stream of the reactor 100 discharge stream are separated at a flow ratio of 70:30, and the second stream of the reactor 100 discharge stream is separated from the devolatilizer 200 ) was mixed with the bottom discharge stream, and the same method as in Example 1 was performed except that the content of the polymer in the mixed stream was controlled to 50 wt%.

As a result, the flow rate and steam usage supplied to the stripper 300 and the flow rate and steam usage supplied to the purification column 600 were measured and shown in Table 1 below.

Example 4

In Example 1, the first stream and the second stream of the reactor 100 discharge stream are separated at a flow ratio of 80:20, and the second stream of the reactor 100 discharge stream is separated from the devolatilizer 200 ) was mixed with the bottom discharge stream, and the same method as in Example 1 was performed except that the content of the polymer in the mixed stream was controlled to 60 wt%.

As a result, the flow rate and steam usage supplied to the stripper 300 and the flow rate and steam usage supplied to the purification column 600 were measured and shown in Table 1 below.

stripper purification column Supply flow (ton/hr) Steam usage (ton/hr) Supply flow (ton/hr) Steam usage (ton/hr) Example 1 85.6 25.2 60.6 17.9 Example 2 63.9 18.8 38.9 11.5 Example 3 49.4 14.6 24.4 7.2 Example 4 42.2 12.4 17.2 5.1

Referring to Table 1, in Examples 1 to 4 according to the present invention, the reactor 100 discharge stream is branched into a first stream and a second stream, and the first stream is sent to the devolatilization device 200 . Concentrate the polymer to a high viscosity by supplying it, volatilize the solvent as much as possible, and control the content of the polymer in the bottom discharge stream to 90% by weight, thereby reducing the cost of the devolatilization unit 200, the stripper 300 and purification By reducing the flow rate supplied to the column 600, the amount of steam used was reduced. In addition, the operation of the stripper 300 by mixing the second stream of the discharge stream at the bottom of the devolatilization unit 200 and the discharge stream of the reactor 100 to control the content of the polymer in the mixed stream to 30% by weight to 60% by weight This made it possible to isolate the polymer with high purity. In particular, it was confirmed that the energy saving effect was greater than that of Examples 3 and 4, in which the content of the polymer in the mixed stream was controlled to 50% to 60% by weight.

comparative example

Comparative Example 1

As shown in the process flow diagram shown in Figure 2, a polymer was prepared.

Specifically, a reaction product including a styrene-butadiene copolymer as a polymer was prepared by supplying a styrene monomer and a 1,3-butadiene monomer as a monomer to the reactor 100, and supplying n-hexane as a solvent for a polymerization reaction. .

The reactor 100 effluent stream was fed to a devolatilizer 200 . At this time, the content of the polymer in the exhaust stream of the reactor 100 was confirmed to be 25% by weight.

The devolatilization device 200 transferred mechanical energy in the form of frictional heat to volatilize the solvent in the reactor 100 effluent stream and discharged it as an overhead effluent stream, and the bottom effluent stream was supplied to the stripper 300 . At this time, the devolatilization device 200 was operated at a temperature of 90 ℃, the content of the polymer in the discharge stream lower than the devolatilization device 200 was confirmed to be 90% by weight.

The devolatilization unit 200 top discharge stream is 95% condensed through the first condenser 400 and then supplied to the condensing solvent tank 500, and separated into gaseous and liquid phases in the condensing solvent tank 500.

In the condensed solvent tank 500 , the liquid phase contains the solvent, discharged as a bottom discharge stream, refluxed to the reactor 100 and immediately reused, and the top discharge stream containing the gas phase passes through the second condenser 410 . After condensing, it was transferred to a purification column (600).

The devolatilization unit 200 bottom discharge stream is mixed with water and supplied to the stripper 300, and the solvent and water are evaporated using hot steam in the stripper 300 to evaporate the solvent and water as a top discharge stream in the purification column 600 ), and the bottom discharge stream containing the polymer and water was subjected to a dehydration process to separate the high-purity polymer.

In the purification column 600 , gaseous impurities and liquid solvent were separated, and the solvent was discharged as a bottom discharge stream of the purification column 600 , and was refluxed to the reactor 100 for reuse.

In this case, the content of the polymer in the bottom discharge stream of the devolatilization device 200 supplied to the stripper 300 is high, and it is difficult to control the size of the crumb due to the high concentration and viscosity. Since it does not evaporate well, there is a problem in that the amount of residual solvent in the crumb increases. In this case, the solvent and impurities remaining in the crumb may be released to the atmosphere together with water vapor in the dehydration step to be described later, which is harmful to the health and environment of workers. There was a problem of the stripper 300 operation was impossible.

Comparative Example 2

In Comparative Example 1, the devolatilization device 200 was operated under conditions to reduce the devolatilization amount of the solvent by supplying a mechanical energy supply amount of 80° C. to half that of Comparative Example 1 to increase the polymer content in the lower discharge stream. It was carried out in the same manner as in Comparative Example 1, except that it was controlled to 40% by weight.

In this case, compared to Comparative Example 1, the concentration of the polymer in the devolatilization device 200 is lowered to enable operation in the stripper 300 at the rear end of the devolatilization device 200, so that the content of the polymer in the lower discharge stream is 40 It was possible to operate in the stripper 300 by controlling the weight %, but as the concentration concentration of the polymer in the devolatilization device 200 was lowered, the required device size increased due to the increase in viscosity, resulting in an increase in device cost there was

100: reactor
200: devolatilization device
300: stripper
400: first condenser
410: second condenser
500: condensing solvent tank
600: purification column

Claims (12)

supplying a feed stream and a solvent stream to the reactor to produce a reaction product;
feeding a first stream of the reactor effluent stream to a devolatilizer to separate a top effluent stream comprising solvent and a bottoms effluent stream comprising polymer;
feeding a second stream of the reactor effluent stream and a mixed stream of the devolatilizer bottoms effluent stream to a stripper; and
separating the overhead effluent stream comprising solvent from the stripper and separating the bottom effluent stream comprising polymer. According to claim 1,
wherein the flow ratio of the first stream and the second stream of the reactor effluent stream is 20:80 to 80:20. The method of claim 1,
wherein the flow ratio of the first stream and the second stream of the reactor effluent stream is 70:30 to 80:20. According to claim 1,
A method for producing a polymer wherein the content of the polymer in the devolatilizer bottoms outlet stream is at least 80% by weight. According to claim 1,
wherein the devolatilization unit transfers mechanical energy in the form of frictional heat to volatilize the solvent in the first stream of the reactor effluent stream. According to claim 1,
wherein the devolatilizer overhead effluent stream passes through a first condenser and is supplied to a condensing solvent tank, and the bottom effluent stream comprising a liquid solvent in the condensing solvent tank is refluxed to the reactor. 7. The method of claim 6,
wherein the gaseous overhead effluent stream from the condensing solvent tank is fed to the purification column via a second condenser. 8. The method of claim 7,
and a bottoms effluent stream comprising solvent from the purification column is refluxed to the reactor. According to claim 1,
The content of the polymer in the mixed stream is 30% to 60% by weight of the polymer production method. According to claim 1,
The polymer content in the mixed stream is 50% to 60% by weight. According to claim 1,
wherein the mixed stream is mixed with water before being fed to the stripper. According to claim 1,
and dewatering the stripper bottoms effluent stream.

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