Method for producing olefin-based elastomers

Abstract

The present invention provides a method for producing an olefin-based elastomer, comprising the steps of: supplying a circulating stream containing unreacted olefin comonomer and residual solvent, a solvent stream containing solvent, and a comonomer stream containing olefin comonomer to a distillation column; obtaining an upper discharge stream from the distillation column containing low-boiling-point components, a lower discharge stream from the distillation column containing high-boiling-point components, and a side discharge stream from the distillation column containing olefin comonomer and solvent by distillation performed in the distillation column; supplying the side discharge stream from the distillation column and the monomer stream containing olefin monomer to a polymerization reactor and copolymerizing them to obtain a discharge stream from the polymerization reactor containing an olefin-based elastomer solution; and supplying the discharge stream from the polymerization reactor containing the olefin-based elastomer solution to a flash drum to obtain an olefin-based elastomer.

Description

[Technical Field]

[0001] This application claims priority under Korean Patent Application No. 10-2023-0073348 dated June 8, 2023, and all content disclosed in the documents of the said Korean Patent Application is incorporated herein by reference.

[0002] The present invention relates to a method for producing olefin-based elastomers, and more particularly to a method for producing olefin-based elastomers by purifying and reusing recovered raw materials after the production of the olefin-based elastomer. [Background technology]

[0003] The lower the density of an olefin compound, the more elastic it becomes, similar to synthetic rubber; this is known as an olefin elastomer. These olefin elastomers possess excellent elasticity, processability, and impact strength, and are used not only as reinforcers for physical properties such as impact and bending strength in automotive interior and exterior materials, but also in various fields such as advanced fibers, the sports industry, and materials for extrusion coatings.

[0004] To produce such olefin-based elastomers, a solution polymerization method can be used. This solution polymerization method involves dissolving monomers and comonomers in a solvent and copolymerizing them in the presence of a catalyst. After obtaining the copolymer olefin-based elastomer, the remaining solvent may contain unreacted comonomers from the copolymerization process.

[0005] Therefore, the residual solvent and unreacted comonomer were fed into two or more distillation columns for reuse as raw materials for producing olefin-based elastomers, and purified to separate them into solvent and comonomer. However, when purification was performed using two or more distillation columns, the energy consumption increased excessively due to the use of multiple distillation columns. [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] The problem that the present invention aims to solve is to provide a method for producing olefin-based elastomers that simplifies the process and reduces energy consumption by recovering the raw materials used in the production of olefin-based elastomers, specifically the solvent and unreacted olefin copolymer, and purifying them in the distillation column of the present invention, in order to solve the problems mentioned in the background art of the invention described above. [Means for solving the problem]

[0007] According to one embodiment of the present invention for solving the above problems, the present invention provides a method for producing an olefin-based elastomer, comprising the steps of: supplying a cycle stream containing unreacted olefin comonomer and residual solvent, a solvent stream containing solvent, and a comonomer stream containing olefin comonomer to a distillation column; obtaining an upper discharge stream of the distillation column containing low-boiling-point components, a lower discharge stream of the distillation column containing high-boiling-point components, and a side discharge stream of the distillation column containing olefin comonomer and solvent by distillation performed in the distillation column; supplying the side discharge stream of the distillation column and the monomer stream containing olefin monomer to a polymerization reactor and copolymerizing them to obtain a discharge stream of the polymerization reactor containing an olefin-based elastomer solution; and supplying the discharge stream of the polymerization reactor containing the olefin-based elastomer solution to a flash drum to obtain an olefin-based elastomer. [Effects of the Invention]

[0008] According to the method for producing olefin-based elastomers of the present invention, when purifying the residual solvent and unreacted olefin comonomer recovered after the copolymerization reaction of an olefin monomer and an olefin comonomer, and the new solvent and olefin comonomer, by using a single distillation column, the energy consumption can be further reduced compared to conventional methods that used multiple distillation columns, which is advantageous from an economic standpoint, such as process equipment costs. Specifically, by controlling the weight ratio of solvent to olefin comonomer in the side discharge stream of the distillation column of the present invention and the position of the side from which the side discharge stream of the distillation column is discharged, the purification that was conventionally performed by multiple distillation columns for the recovered residual solvent and unreacted olefin comonomer and the new solvent and olefin comonomer can be performed by the distillation column design of the present invention. Furthermore, by this control, the content of high-boiling-point components in the side discharge stream of the distillation column can be reduced, thereby preventing fouling, and by immediately supplying the side discharge stream of the distillation column to the polymerization reactor, the copolymerization reaction carried out in the polymerization reactor can be activated. [Brief explanation of the drawing]

[0009] [Figure 1] This is a flowchart illustrating a method for producing an olefin-based elastomer according to one embodiment of the present invention. [Figure 2] This is a flowchart illustrating a method for producing an olefin-based elastomer according to one embodiment of the present invention. [Figure 3] This is a flowchart illustrating the process for producing an olefin-based elastomer according to a comparative example of the present invention. [Figure 4] This is a flowchart illustrating the process for producing an olefin-based elastomer according to a comparative example of the present invention. [Modes for carrying out the invention]

[0010] The terms and words used in the description and claims of this invention should not be interpreted in a manner limited to their ordinary or dictionary meanings, but rather should be interpreted in a manner consistent with the technical idea of ​​this invention, in accordance with the principle that inventors may appropriately define the concepts of terms in order to best describe their invention.

[0011] In this invention, the term "stream" may mean the flow of fluid within a process, or the fluid itself flowing within a pipe. Specifically, "stream" may simultaneously mean the fluid itself and the flow of fluid within the pipes connecting each device. Furthermore, the fluid may be a gas or a liquid, and does not exclude cases where the fluid contains solid components.

[0012] On the other hand, in the present invention, in apparatus such as a distillation column and a flash drum, the "lower part" of the apparatus means a point at a height of 80% to 100% below the top of the apparatus, unless otherwise specified, and specifically may mean the lowest point (bottom of the column). Similarly, the "upper part" of the apparatus means a point at a height of 0% to 20% below the top of the apparatus, unless otherwise specified, and specifically may mean the top (top of the column).

[0013] To facilitate understanding of the present invention, the present invention will be described in more detail below with reference to Figure 1.

[0014] The method for producing an olefin-based elastomer according to an embodiment of the present invention includes steps of: supplying a circulation stream 1 containing unreacted olefin comonomer and residual solvent, a solvent stream 2 containing a solvent, and a comonomer stream 3 containing an olefin comonomer to a distillation column 100; obtaining an upper discharge stream of the distillation column containing low-boiling components, a lower discharge stream of the distillation column containing high-boiling components, and a side discharge stream of the distillation column containing an olefin comonomer and a solvent by distillation performed in the distillation column 100; supplying the side discharge stream of the distillation column and a monomer stream 4 containing an olefin monomer to a polymerization reactor 200, copolymerizing to obtain a discharge stream of the polymerization reactor containing an olefin-based elastomer solution; and supplying the discharge stream of the polymerization reactor containing the olefin-based elastomer solution to a flash drum 300 to obtain an olefin-based elastomer.

[0015] First, the copolymerization reaction according to an embodiment of the present invention can be carried out by copolymerizing a reactant containing an olefin monomer and an olefin comonomer in the presence of a solvent, and an olefin-based elastomer as a copolymer can be obtained by copolymerizing the reactant.

[0016] Here, the olefin monomer can be any one selected from an alpha-olefin monomer, a cyclic olefin monomer, a diene olefin monomer, a triene olefin monomer, and a styrene monomer, and in the present invention, it can be an alpha-olefin monomer. More specifically, the alpha-olefin monomer can contain one or more of ethylene and propylene.

[0017] On the one hand, the olefin comonomer can be an alpha-olefin comonomer. Specifically, the alpha-olefin comonomer can include any one or a mixture of two or more selected from the group consisting of 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-heptene, 1-octene, 1-decene, 1-undecene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, norbornene, norbornadiene, ethylidene norbornene, phenyl norbornene, vinyl norbornene, dicyclopentadiene, 1,4-butadiene, 1,5-pentadiene, 1,6-hexadiene, styrene, alpha-methylstyrene, divinylbenzene, and 3-chloromethylstyrene. The olefin comonomer in the present invention can be 1-butene or 1-octene.

[0018] More specifically, when the olefin comonomer is 1-butene, the reactants can include, for example, ethylene and 1-butene. When the olefin comonomer is 1-octene, the reactants can include, for example, ethylene and 1-octene.

[0019] First, the method for producing the olefin-based elastomer can be carried out by including the step of supplying a circulation stream 1 containing unreacted olefin comonomer and residual solvent, a solvent stream 2 containing solvent, and a comonomer stream 3 containing olefin comonomer to a distillation column 100.

[0020] The circulating stream 1 containing the unreacted olefin comonomer and residual solvent can be derived from the stream separated from the olefin elastomer in the flash drum 300, which will be described later. The unreacted olefin comonomer and residual solvent may be olefin comonomers that were not copolymerized during the copolymerization of the olefin monomer and the olefin comonomer, and solvents used during the copolymerization, which were separated from the olefin elastomer in the flash drum 300. In order to reuse the raw materials used during the copolymerization, the circulating stream 1 containing the unreacted olefin comonomer and residual solvent can be supplied to the distillation column 100 for purification to separate impurities contained in the circulating stream 1.

[0021] On the other hand, solvent stream 2 containing the solvent can be a stream containing fresh solvent, and can be a stream for newly replenishing the solvent necessary for copolymerization of the olefin monomer and the olefin copolymer.

[0022] Specifically, the solvent can be a hydrocarbon solvent having 5 to 12 carbon atoms, and more specifically, it can be one or more of hexane, cyclohexane, methylcyclohexane, heptane, nonane, decane, toluene, and benzene. More specifically, the solvent can be hexane. When an olefin monomer and an olefin comonomer are copolymerized using the solvent, the solvent makes it easier to dissolve the olefin monomer and olefin comonomer, thereby making copolymerization of the dissolved olefin monomer and olefin comonomer easier.

[0023] On the other hand, the comonomer stream 3 containing the olefin comonomer is a stream containing fresh olefin comonomers and can be a stream for newly replenishing the polymerization reactor 200 with olefin comonomers, which are raw materials used when producing olefin-based elastomers.

[0024] On the other hand, the comonomer stream 3 may contain undesirable impurities in addition to the new olefin comonomer. If the comonomer stream 3 is supplied to the polymerization reactor 200 without removing the impurities and a copolymerization reaction is carried out, the impurities may cause side reactions during copolymerization, potentially reducing the amount of olefin elastomer obtained by copolymerization. Therefore, it is necessary to remove the impurities contained in the comonomer stream 3 beforehand before supplying it to the polymerization reactor 200. However, if a separate column is provided to remove only the impurities contained in the comonomer stream 3, it may be economically undesirable due to increased process equipment costs and excessive energy use. Therefore, it is preferable to supply the comonomer stream 3 to the distillation column 100 that purifies the circulation stream 1 and purify them together.

[0025] On the other hand, conventionally, in order to separate impurities contained in the circulation stream 1, solvent stream 2, and comonomer stream 3, it was necessary to purify them using multiple distillation columns. However, in the present invention, by controlling the weight ratio of solvent and olefin comonomer in the side discharge stream of the distillation column and the height of the side from which the side discharge stream of the distillation column is discharged, the circulation stream 1, solvent stream 2, and comonomer stream 3 can be purified using only the distillation column 100 according to the present invention.

[0026] On the other hand, the circulation stream 1, solvent stream 2, and comonomer stream 3 may be supplied directly to the distillation column 100, but the supply of the circulation stream 1, solvent stream 2, and comonomer stream 3 to the distillation column 100 can be varied in various ways.

[0027] For example, according to another embodiment of the present invention (see Figure 2), the circulation stream 1, solvent stream 2, and comonomer stream 3 can be supplied by mixing the circulation stream 1 and solvent stream 2 and supplying them to the distillation column 100, and supplying the comonomer stream 3 directly to the distillation column 100. The mixing of the circulation stream 1 and solvent stream 2 can be performed in the recovery tank 10.

[0028] Furthermore, supplying the mixed circulation stream 1 and solvent stream 2 to the distillation column 100 may involve supplying the mixed stream of circulation stream 1 and solvent stream 2 to the distillation column via the heat exchanger 20. Specifically, the mixed stream may be a mixture of circulation stream 1 and solvent stream 2 obtained in the recovery tank 10. The mixed stream can pass through the heat exchanger 20, where the mixed stream can be preheated using low-pressure steam (LS). By supplying the preheated mixed stream from the heat exchanger 20 to the distillation column 100, the amount of medium-pressure steam (MS) used in the reboiler 40 of the distillation column 100 can be further reduced, which is preferable in terms of energy use. Moreover, the medium-pressure steam is a higher-grade steam than the low-pressure steam used in the heat exchanger 20, and reducing the amount of medium-pressure steam used improves the economic efficiency of the process.

[0029] A method for producing an olefin-based elastomer according to one embodiment of the present invention can be carried out by distillation performed in the distillation column 100, which includes the steps of obtaining an upper discharge stream of the distillation column containing low-boiling-point components, a lower discharge stream of the distillation column containing high-boiling-point components, and a side discharge stream of the distillation column containing an olefin copolymer and a solvent.

[0030] Specifically, the distillation performed in the distillation column 100 can separate the product into an upper fraction containing low-boiling-point components, a lower fraction containing high-boiling-point components, and a side fraction containing an olefin copolymer and a solvent.

[0031] The low-boiling-point components may include nitrogen, hydrogen, methane, ethane, ethylene, and propane, while the high-boiling-point components may include iso-octene, carbon compounds of C9 or higher, and oligomers (molecular weight 1000-10000 g / mol). The upper fraction containing the low-boiling-point components can be discharged via the upper discharge stream of the distillation column, and the lower fraction containing the high-boiling-point components can be discharged via the lower discharge stream of the distillation column. In this way, impurities contained in the circulation stream 1, solvent stream 2, and copolymer stream 3 can be removed by discharging impurities via the upper and lower discharge streams of the distillation column.

[0032] As described above, by separating the impurities via the upper and lower discharge streams of the distillation column and obtaining a side discharge stream containing the side fraction, the solvent and olefin copolymer contained in the side discharge stream can be made suitable for use as a raw material for producing olefin-based elastomers.

[0033] On the other hand, referring to Figure 3, conventionally, monomers and comonomers were copolymerized in the presence of a solvent to obtain a copolymer. Then, the residual solvent containing unreacted comonomers was recovered and distilled in a distillation column together with a new solvent and a new olefin comonomer to separate the solvent and comonomers, respectively. In order to reuse the solvent and comonomers thus separated as raw materials for the copolymer, two or more distillation columns were required to remove the low-boiling-point components contained in the separated solvent and the high-boiling-point components contained in the separated comonomers. However, when obtaining solvents and comonomers from which impurities have been removed by at least three or more distillation columns in this way, the operation of numerous distillation columns excessively increased process equipment costs and energy consumption.

[0034] Unlike conventional methods that used at least three or more distillation columns to remove impurities, this invention utilizes a single functional distillation column 100, including the discharge of a side stream, to purify a new solvent, a new olefin comonomer, recovered residual solvent, and unreacted olefin comonomer, thereby obtaining a solvent and olefin comonomer from which low-boiling and high-boiling components have been removed. Specifically, by controlling the weight ratio of the solvent and olefin comonomer in the side discharge stream of the distillation column and the height of the side from which the side discharge stream is discharged, the separation and removal of low-boiling and high-boiling components can be activated even with only the distillation column according to one embodiment of the present invention. This is preferable in terms of energy and economy compared to conventional methods. Furthermore, the side discharge stream of the distillation column containing the solvent and olefin comonomer can be directly supplied to the polymerization reactor 200 without separating the solvent and comonomer as in conventional methods.

[0035] According to one embodiment of the present invention, the weight ratio of solvent to olefin comonomer contained in the side discharge stream of the distillation column can be 1.28 to 1.58, specifically 1.28 to 1.48 or 1.28 to 1.37. When the weight ratio of solvent to olefin comonomer contained in the side discharge stream of the distillation column is within the above range, it may be suitable for supplying the side discharge stream of the distillation column to the polymerization reactor 200 to produce an olefin-based elastomer. That is, if the weight ratio of solvent to olefin comonomer contained in the side discharge stream of the distillation column is less than 1.28, the flow rate of the lower discharge stream of the distillation column may be very low or nonexistent, making it impossible to operate the distillation column 100. Even if the distillation column 100 can be operated, the content of high-boiling-point components in the side discharge stream of the distillation column increases, and fouling may occur from these high-boiling-point components. If the weight ratio of solvent to olefin comonomer contained in the side discharge stream of the distillation column exceeds 1.58, the recovery rate of olefin comonomer from the side discharge stream of the distillation column decreases, and activation of copolymerization carried out in the polymerization reactor 200 may become difficult. Therefore, the yield of the olefin-based elastomer to be obtained in the present invention may decrease.

[0036] The side discharge stream of the distillation column can be discharged from the side at a height of 60-77%, 62-73%, or 66-70% from the top to the bottom of the distillation column. When the height of the side from which the side discharge stream of the distillation column is discharged is within the above range, the weight ratio of solvent to olefin comonomer contained in the side discharge stream of the distillation column can be easily controlled. Specifically, the weight ratio of solvent to olefin comonomer contained in the side discharge stream of the distillation column can be controlled by the flow rates of solvent stream 2 and comonomer stream 3, but the flow rates of solvent stream 2 and comonomer stream 3 may be difficult to flexibly accommodate process requirements, such as product production volume and product grade, within a limited flow rate range. Therefore, by controlling the height of the side from which the side discharge stream of the distillation column is discharged, the weight ratio of solvent to olefin comonomer contained in the side discharge stream of the distillation column can be controlled to 1.28-1.58.

[0037] Specifically, if the height of the side from which the side discharge stream of the distillation column is discharged is less than 60%, the weight of low-boiling-point components in the side discharge stream of the distillation column may increase, and if the height of the side from which the side discharge stream of the distillation column is discharged is greater than 77%, the weight of high-boiling-point components in the side discharge stream of the distillation column may increase. In other words, if the height of the side from which the side discharge stream of the distillation column is discharged deviates from the above range (60-77%), the content of impurities in the side discharge stream of the distillation column may increase excessively, and when the side discharge stream of the distillation column is supplied to the polymerization reactor 200, the copolymerization of olefin monomers and olefin comonomers carried out in the polymerization reactor 200 may not be activated.

[0038] A distillation column 100 according to one embodiment of the present invention can be a conventional distillation column, and such conventional distillation column can be a single-region distillation column that does not include structures that partition laterally within the distillation column. Specifically, since the distillation column 100 of the present invention does not include structures that partition laterally, for example, the left and right regions within the distillation column, where the composition, operating temperature, and operating pressure differ, can not be separated. For example, the distillation column 100 can be a distillation column without a separation wall.

[0039] According to the present invention, the temperature at the bottom of the distillation column can be 120 to 180°C, specifically 130 to 170°C or 149 to 156°C. When the temperature at the bottom of the distillation column is controlled within this range, the amount of solvent and / or olefin comonomer lost through the upper and lower discharge streams of the distillation column can be minimized. Therefore, because the amount of solvent and / or olefin comonomer lost is small, as much solvent and olefin comonomer as possible can be included in the side discharge streams of the distillation column.

[0040] On the other hand, the pressure at the top of the distillation column is 0.7 to 1.0 kg / cm². 2 It can be 0.75-0.95 kg / cm³. 2 g or 0.85-0.9 kg / cm³ 2 It can be g. When distillation is performed under the pressure conditions at the top of such a distillation column, the distillation column 100 can easily separate the upper fraction containing low-boiling-point components, the lower fraction containing high-boiling-point components, and the side fraction containing the solvent and the olefin copolymer.

[0041] On the other hand, the upper reflux ratio of the flow rate of the upper reflux stream of the distillation column to the flow rate of the upper discharge stream of the distillation column can be 60 to 75, specifically 62 to 70 or 64 to 68. The upper discharge stream of the distillation column passes through the condenser 30, with a portion refluxing to the distillation column 100 and the remainder being discharged. In this case, the portion of the stream that refluxes to the distillation column 100 can be the upper reflux stream of the distillation column.

[0042] Furthermore, the lower reflux ratio of the flow rate of the lower reflux stream of the distillation column to the flow rate of the lower discharge stream of the distillation column can be 20 to 220, specifically 22 to 215 or 24 to 213. A portion of the lower discharge stream of the distillation column refluxes to the distillation column 100 via the reboiler 40, and the remainder is discharged. In this case, the portion of the stream that refluxes to the distillation column 100 can be the lower reflux stream of the distillation column.

[0043] A method for producing an olefin-based elastomer according to one embodiment of the present invention may include the step of supplying the side discharge stream of the distillation column and a monomer stream 4 containing olefin monomers to a polymerization reactor 200, copolymerizing them to obtain a polymerization reactor discharge stream containing an olefin-based elastomer solution. The monomer stream 4 may be a stream for supplying olefin monomers, which are raw materials used to produce the olefin-based elastomer in the polymerization reactor 200, and may contain fresh olefin monomers.

[0044] On the other hand, the side discharge stream and monomer stream 4 of the distillation column can be cooled via a refrigerator immediately before being supplied to the polymerization reactor 200. However, if the content of high-boiling-point components in the side discharge stream of the distillation column is high, the oligomers contained in the high-boiling-point components will precipitate at low temperatures, which may cause fouling from the oligomers and reduce the efficiency of the copolymerization reaction.

[0045] According to the present invention, the supply of the side discharge stream of the distillation column and the monomer stream 4 may be carried out by supplying them directly to the polymerization reactor 200, as described above, or by mixing the side discharge stream of the distillation column and the monomer stream 4 and supplying them to the polymerization reactor 200. Here, the mixing of the side discharge stream of the distillation column and the monomer stream 4 can be carried out by supplying the side discharge stream of the distillation column and the monomer stream 4 to the feed tank 50.

[0046] According to one embodiment of the present invention, the weight flow rate ratio of the olefin comonomer to the olefin monomer supplied to the polymerization reactor 200 can be 0.8 to 1.5, 0.85 to 1.4, or 0.9 to 1.3. By controlling the weight flow rate ratio of the olefin comonomer to the olefin monomer supplied to the polymerization reactor 200 within the above range, the physical properties of the olefin-based elastomer, which is the final product to be obtained in the present invention, can be adjusted to a desired level.

[0047] If the weight flow rate ratio of olefin comonomers to olefin monomers supplied to the polymerization reactor 200 is less than 0.8, more olefin comonomers than necessary may be supplied to the polymerization reactor 200, which may be economically undesirable in terms of raw material utilization. In addition, the content of olefin comonomers in the final obtained olefin-based elastomer may increase, potentially reducing the density, which is one of the quality elements of the final product. If the weight flow rate ratio of olefin comonomers to olefin monomers supplied to the polymerization reactor 200 is greater than 1.5, the amount of olefin comonomers supplied to the polymerization reactor 200 may be insufficient, potentially reducing the efficiency of the copolymerization reaction carried out in the polymerization reactor 200, leading to an excessive increase in the density of the final product, making it impossible to obtain an olefin-based elastomer with the desired physical properties.

[0048] On the other hand, in the polymerization reactor 200, a reaction product containing an olefin monomer and an olefin copolymer can be copolymerized in the presence of a solvent to obtain an olefin-based elastomer solution containing an olefin-based elastomer, which is a copolymer. Here, the polymerization reactor 200 may further include a catalyst and a co-catalyst, the catalyst may include a metallocene catalyst, and the co-catalyst may include one or more of triethylaluminoxane (TEAL), methylaluminoxane (MAO), and borate.

[0049] The copolymerization of the reactants can be carried out in liquid phase, slurry phase, bulk phase, or gas phase polymerization. In the present invention, this can be done by liquid phase polymerization, i.e., solution polymerization. Solution polymerization is a method of polymerization in which monomers are dissolved in a solvent and polymerized in a solution state. After polymerization is completed, a polymer solution can be obtained in which the polymer is dissolved or dispersed in the solvent.

[0050] On the other hand, the copolymerization temperature of the olefin monomer and olefin comonomer in the polymerization reactor 200 can be 140 to 180°C, and the pressure can be 80 to 100 kg / cm². 2 It can be g. When the polymerization reactor 200 is operated under the above operating conditions, copolymerization of the olefin monomer and the olefin comonomer can be easily carried out, and the yield of olefin-based elastomers can be increased.

[0051] A method for producing an olefin-based elastomer according to one embodiment of the present invention can be carried out by supplying the discharge stream of a polymerization reactor containing the olefin-based elastomer solution to a flash drum 300 to obtain the olefin-based elastomer. Specifically, the olefin-based elastomer, which is a copolymer of an olefin monomer and an olefin comonomer, can be separated and obtained from the olefin-based elastomer solution in the flash drum 300. Here, the olefin-based elastomer has a density of 0.875 g / cm³. 3 The following ultra-low density polyolefins are possible.

[0052] Here, the flash drum 300 operates under the following conditions: a temperature of 160-240°C and a load of 10-17 kg / cm². 2 It can be operated under a pressure of g. When the olefin-based elastomer is separated under the operating conditions of the flash drum 300, the olefin-based elastomer can be separated more easily in the flash drum 300, and a circulating stream 1 derived from the stream separated from the olefin-based elastomer can be obtained.

[0053] As described above, the circulating stream 1 derived from the stream separated from the olefin-based elastomer in the flash drum 300 may contain residual solvent and unreacted olefin comonomers. By purifying the residual solvent and unreacted olefin comonomers contained in the circulating stream 1 in the distillation column 100 and reusing them as raw materials for producing the olefin-based elastomer, the amount of solvent and olefin comonomers that must be newly supplied during the process can be minimized. Therefore, process costs for supplying new raw materials can be reduced, which is economically preferable.

[0054] The present invention will be described in more detail below with reference to examples. However, the following examples are for illustrative purposes only, and it will be obvious to an ordinary person that various changes and modifications are possible within the scope of the present invention and the technical idea, and the scope of the present invention is not limited by these examples alone.

[0055] Examples Example 1 The manufacturing process for olefin-based elastomers was simulated using the Aspen Plus simulator from Aspen Corporation, following the process flowchart shown in Figure 1.

[0056] Specifically, a circulation stream 1 containing unreacted olefin comonomer (unreacted 1-octene) and residual solvent (residual hexane), a solvent stream 2 containing new solvent (hexane), and a comonomer stream 3 containing new olefin comonomer (1-octene) were supplied to the distillation column 100.

[0057] Distillation in the distillation column 100 yielded an upper discharge stream containing low-boiling-point components, a lower discharge stream containing high-boiling-point components, and a side discharge stream containing an olefin copolymer and solvent. The temperature at the bottom of the distillation column was 149°C, and the pressure at the top of the distillation column was 0.82 kg / cm². 2 The reflux ratio of the flow rate of the upper reflux stream of the distillation column to the flow rate of the upper discharge stream of the distillation column was 66.7, and the reflux ratio of the flow rate of the lower reflux stream of the distillation column to the flow rate of the lower discharge stream of the distillation column was 32.6.

[0058] On the one hand, the side discharge stream of the distillation column was discharged from the side at a height of 67% from the top to the bottom of the distillation column 100. The weight ratio of the solvent to the olefin comonomer contained in the side discharge stream of the distillation column was 1.34. Also, the content (impurity content) of the high-boiling components contained in the side discharge stream of the distillation column was 0.2 ppm. Here, the composition of the side discharge stream of the distillation column was measured by FT-IR (Fourier transform infrared spectroscopy).

[0059] The side discharge stream of the distillation column and the monomer stream 4 containing a new olefin monomer (ethylene) were fed into the polymerization reactor 200 and copolymerized in the presence of a metallocene catalyst and a cocatalyst to obtain a discharge stream of the polymerization reactor containing an olefin-based elastomer solution. Here, the weight flow rate ratio of the olefin comonomer to the olefin monomer fed into the polymerization reactor 200 was 0.96. Here, the polymerization reactor 200 was operated at a temperature of 170 °C and a pressure of 95 kg / cm 2 ·g.

[0060] The discharge stream of the polymerization reactor containing the olefin-based elastomer solution was fed into the flash drum 300, and finally, an olefin-based elastomer was obtained. Here, the flash drum 300 was operated at a temperature of 200 °C and a pressure of 10 kg / cm 2 ·g. The recycle stream 1 containing the unreacted olefin comonomer and the residual solvent derived from the stream separated from the olefin-based elastomer in the flash drum 300 was recycled to the recovery tank 10.

[0061] As a result, the energy reduction rate in the reboiler 40 of the distillation column 100 was 51%. The energy reduction rate is a value indicating the difference in energy usage between the reboiler of Comparative Example 1 (3.73 Gcal / h), which has the highest total energy usage in the reboiler of the distillation column, and the reboiler of Example 1 as a percentage.

[0062] On the other hand, the recovery rate in the distillation column 100 was 99.4% by weight for hexane and 94.5% by weight for 1-octene. The hexane recovery rate is expressed as a percentage of the weight ratio of hexane contained in the side discharge stream of the distillation column to the weight of hexane contained in the circulation stream 1 and solvent stream 2. The 1-octene recovery rate is expressed as a percentage of the weight ratio of 1-octene contained in the side discharge stream of the distillation column to the weight of 1-octene contained in the circulation stream 1 and copolymer stream 3.

[0063] Example 2 The manufacturing process for olefin-based elastomers was simulated using the Aspen Plus simulator from Aspen Corporation, following the process flowchart shown in Figure 2.

[0064] Specifically, a circulation stream 1 containing unreacted olefin comonomer (unreacted 1-octene) and residual solvent (residual hexane), and a solvent stream 2 containing new solvent (hexane) were supplied to the recovery tank 10 and mixed to obtain a mixed stream of circulation stream 1 and solvent stream 2, which was then supplied to the distillation column 100 via the heat exchanger 20. On the other hand, a comonomer stream 3 containing new olefin comonomer (1-octene) was supplied directly to the distillation column 100.

[0065] The distillation performed in the distillation column 100 yielded an upper discharge stream containing low-boiling-point components, a lower discharge stream containing high-boiling-point components, and a side discharge stream containing an olefin copolymer and solvent. Here, the temperature at the bottom of the distillation column was 149°C, and the pressure at the top of the distillation column was 0.82 kg / cm². 2 The reflux ratio of the flow rate of the upper reflux stream of the distillation column to the flow rate of the upper discharge stream of the distillation column was 66.7, and the reflux ratio of the flow rate of the lower reflux stream of the distillation column to the flow rate of the lower discharge stream of the distillation column was 32.6.

[0066] On the other hand, the side discharge stream of the distillation column was discharged from the side of the distillation column 100 at a height of 67% from the top to the bottom. The weight ratio of solvent to olefin comonomer contained in the side discharge stream of the distillation column was 1.34. In addition, the content of high-boiling point components (impurity content) contained in the side discharge stream of the distillation column was 3.0 ppm. Here, the composition of the side discharge stream of the distillation column was measured by FT-IR (Fourier transform infrared spectroscopy).

[0067] The side discharge stream from the distillation column and the monomer stream 4 containing a new olefin monomer (ethylene) were supplied to the feed tank 50, mixed, and supplied to the polymerization reactor 200. In the polymerization reactor 200, copolymerization of the olefin monomer and the olefin comonomer took place in the presence of a metallocene catalyst and a co-catalyst, yielding a polymerization reactor discharge stream containing an olefin-based elastomer solution. The polymerization reactor 200 was operated at a temperature of 175°C and a load of 90 kg / cm³. 2 The reactor was operated at a pressure of 0.96 g. Here, the weight flow rate ratio of the olefin comonomer to the olefin monomer supplied to the polymerization reactor 200 was 0.96.

[0068] The discharge stream from the polymerization reactor containing the olefin-based elastomer solution was supplied to the flash drum 300, and finally, the olefin-based elastomer was obtained. Here, the flash drum 300 was operated at a temperature of 200°C and a load of 10 kg / cm³. 2 The system was operated at a pressure of 1.g. The circulating stream 1, which contained unreacted olefin comonomers and residual solvent derived from the stream separated from the olefin elastomer in the flash drum 300, was circulated to the recovery tank 10.

[0069] As a result, the energy reduction rate in the reboiler 40 of the distillation column 100 was 64%. On the other hand, the recovery rate in the distillation column 100 was 99.5% by weight for hexane and 94.6% for 1-octene.

[0070] Example 3 In Example 3, an olefin-based elastomer was produced using the same process as in Example 2, except that the weight ratio of solvent to olefin comonomer in the side discharge stream of the distillation column was 1.40. The impurity (high-boiling point component) content in the side discharge stream of the distillation column was 1.5 ppm.

[0071] As a result, the energy reduction rate in the reboiler 40 of the distillation column 100 was 64%. On the other hand, the recovery rate in the distillation column 100 was 99.4% by weight for hexane and 90.7% by weight for 1-octene.

[0072] Example 4 In Example 4, an olefin-based elastomer was produced using the same process as in Example 2, except that the weight ratio of solvent to olefin comonomer in the side discharge stream of the distillation column was 1.27. The impurity (high-boiling point component) content in the side discharge stream of the distillation column was 362 ppm.

[0073] As a result, the energy reduction rate in the reboiler 40 of the distillation column 100 was 64%. On the other hand, the recovery rate in the distillation column 100 was 99.5% by weight for hexane and 99.0% by weight for 1-octene.

[0074] Example 5 Example 5 produced an olefin-based elastomer using the same process as Example 2, except that the weight ratio of solvent to olefin comonomer in the side discharge stream of the distillation column was 1.28. The impurity (high-boiling point component) content in the side discharge stream of the distillation column was 25 ppm.

[0075] As a result, the energy reduction rate in the reboiler 40 of the distillation column 100 was 64%. On the other hand, the recovery rate in the distillation column 100 was 99.5% by weight for hexane and 99.4% by weight for 1-octene.

[0076] Comparative Example Comparative Example 1 The manufacturing process for olefin-based elastomers was simulated using the Aspen Plus simulator from Aspen Corporation, following the process flowchart shown in Figure 3.

[0077] A circulation stream 1 containing unreacted olefin comonomer (unreacted 1-octene) and residual solvent (residual hexane), and a solvent stream 2 containing new solvent (hexane) were supplied to the recovery tank 10 and mixed to obtain a mixed stream of circulation stream 1 and solvent stream 2, which was supplied to the first distillation column 400 via the heat exchanger 20. Meanwhile, a comonomer stream 3 containing new olefin comonomer (1-octene) was supplied directly to the first distillation column 400.

[0078] The distillation performed in the first distillation column 400 yielded an upper discharge stream containing low-boiling components and solvent, and a lower discharge stream containing high-boiling components and olefin copolymers. Here, the temperature at the bottom of the first distillation column was 136°C, and the pressure at the top of the first distillation column was 0.82 kg / cm². 2 It was g.

[0079] The upper discharge stream of the first distillation column was supplied to the second distillation column 500, where it was separated into an upper fraction containing low-boiling-point components and a lower fraction containing the solvent. The lower fraction containing the solvent was supplied to the feed tank 50 via the lower discharge stream of the second distillation column. Here, the temperature at the bottom of the second distillation column was 95°C, and the pressure at the top of the second distillation column was 0.82 kg / cm². 2 It was g.

[0080] Meanwhile, the lower discharge stream of the first distillation column was supplied to the third distillation column 600, where it was separated into an upper fraction containing the olefin comonomer and a lower fraction containing the high-boiling point component. The upper fraction containing the olefin comonomer was supplied to the feed tank 50 via the upper discharge stream of the third distillation column. At this time, the temperature at the bottom of the third distillation column was 145°C, and the pressure at the top of the third distillation column was 0.4 kg / cm². 2The amount was 1.2 g. The weight ratio of the solvent contained in the lower discharge stream of the second distillation column to the weight of the olefin comonomer contained in the upper discharge stream of the third distillation column was 1.2. In addition, the total high-boiling point component content (impurity content) contained in the upper discharge stream of the third distillation column and the lower discharge stream of the second distillation column was 25 ppm.

[0081] In addition to the lower discharge stream of the second distillation column and the upper discharge stream of the third distillation column, a monomer stream 4 containing a new olefin monomer (ethylene) was supplied to the feed tank 50, mixed, and supplied to the polymerization reactor 200. Here, the weight flow rate ratio of the olefin comonomer to the olefin monomer supplied to the polymerization reactor 200 was 0.96. In the polymerization reactor 200, copolymerization of the olefin monomer and the olefin comonomer was carried out in the presence of a metallocene catalyst and a co-catalyst to obtain an olefin-based elastomer solution. Here, the polymerization reactor 200 was operated at a temperature of 175°C and a flow rate of 90 kg / cm³. 2 It was operated at a pressure of 1g.

[0082] The olefin-based elastomer solution was supplied to the flash drum 300 to finally obtain the olefin-based elastomer. Here, the flash drum 300 was maintained at a temperature of 200°C and a load of 10 kg / cm³. 2 The system was operated at a pressure of 1.g. The circulating stream 1, which contained unreacted olefin comonomers and residual solvent derived from the stream separated from the olefin elastomer in the flash drum 300, was circulated to the recovery tank 10.

[0083] As a result, the total energy consumption of the reboilers in the distillation columns (first, second, and third distillation columns) was 3.73 Gcal / h.

[0084] On the other hand, the recovery rates in the distillation columns (first, second, and third distillation columns) were 87.8% by weight for hexane and 93.5% by weight for 1-octene. The hexane recovery rate is expressed as a percentage of the weight ratio of hexane contained in the lower discharge stream of the second distillation column to the weight of hexane contained in the circulation stream 1 and solvent stream 2. The 1-octene recovery rate is expressed as a percentage of the weight ratio of 1-octene contained in the upper discharge stream of the third distillation column to the weight of 1-octene contained in the circulation stream 1 and copolymer stream 3.

[0085] Comparative Example 2 The manufacturing process for olefin-based elastomers was simulated using the Aspen Plus simulator from Aspen Corporation, following the process flowchart shown in Figure 4.

[0086] A circulation stream 1 containing unreacted olefin comonomer (unreacted 1-octene) and residual solvent (residual hexane), and a solvent stream 2 containing new solvent (hexane) were supplied to the recovery tank 10 and mixed to obtain a mixed stream of circulation stream 1 and solvent stream 2, which was supplied to the separation wall type distillation column 700 via the heat exchanger 20. Meanwhile, a comonomer stream 3 containing new olefin comonomer (1-octene) was supplied directly to the separation wall type distillation column 700.

[0087] Distillation in the separation-wall type distillation column 700 yielded an upper discharge stream containing low-boiling-point components, a side discharge stream containing solvent (hexane) and olefin comonomer (1-octene), and a lower discharge stream containing high-boiling-point components. The side discharge stream was discharged from the side of the separation-wall type distillation column 700 at a height of 65% from the top downwards. The weight ratio of solvent to olefin comonomer in the side discharge stream was 1.33. Here, the temperature at the bottom of the separation-wall type distillation column was 150°C, and the pressure at the top of the separation-wall type distillation column was 0.82 kg / cm².2 It was g.

[0088] Meanwhile, the side discharge stream from the separation wall-type distillation column was supplied to the feed tank 50, and in addition, a monomer stream 4 containing a new olefin monomer (ethylene) was supplied to the feed tank 50, mixed, and supplied to the polymerization reactor 200.

[0089] In the polymerization reactor 200, copolymerization of olefin monomers and olefin copolymers was carried out in the presence of a metallocene catalyst and a co-catalyst to obtain an olefin-based elastomer solution containing an olefin-based elastomer copolymer. Here, the polymerization reactor 200 was set to a temperature of 175°C and a load of 90 kg / cm³. 2 It was operated at a pressure of 1g.

[0090] The olefin-based elastomer solution was supplied to the flash drum 300 to finally obtain the olefin-based elastomer. Here, the flash drum 300 was maintained at a temperature of 200°C and a load of 10 kg / cm³. 2 The system was operated at a pressure of 1.g. The circulating stream 1, which contained unreacted olefin comonomers and residual solvent derived from the stream separated from the olefin elastomer in the flash drum 300, was circulated to the recovery tank 10.

[0091] As a result, the energy reduction rate in the reboiler of the separation wall-type distillation column 700 was 64%.

[0092] On the other hand, the recovery rates in the separation wall type distillation column 700 were 99.4% by weight for hexane and 95.6% by weight for 1-octene. The hexane recovery rate is expressed as a percentage of the weight ratio of hexane contained in the side discharge stream of the separation wall type distillation column to the weight of hexane contained in the circulation stream 1 and solvent stream 2. The 1-octene recovery rate is expressed as a percentage of the weight ratio of 1-octene contained in the side discharge stream of the separation wall type distillation column to the weight of 1-octene contained in the circulation stream 1 and comonomer stream 3.

[0093] Table 1 below shows the operating conditions (by weight), energy reduction rate, recovery rate, and impurity content for each of the examples and comparative examples.

[0094] [Table 1]

[0095] Referring to Table 1, it was confirmed that the example using a single distillation column for the purification of the circulation stream, solvent stream, and comonomer stream showed a significantly increased energy reduction rate compared to Comparative Example 1. On the other hand, in Examples 2 to 4, it was confirmed that the amount of energy used in the reboiler of the distillation column decreased and the energy reduction rate increased compared to Example 1 because the mixed stream of the circulation stream and solvent stream passed through a heat exchanger. Furthermore, in Example 2, it was confirmed that the amount of high-boiling-point components present in the side portion of the distillation column increased compared to Example 1 by supplying the mixed stream to the distillation column in a preheated state via a heat exchanger, and the impurity content in the side discharge stream of the distillation column increased compared to Example 1. However, when the impurity (high-boiling-point component) content in the side discharge stream of the distillation column is less than 50 ppm, problems such as fouling do not occur because the amount of impurities is small.

[0096] On the other hand, in Comparative Example 1, by using three distillation columns, it was confirmed that the total energy consumption in the reboiler of each distillation column was the highest, and it was confirmed that the impurity content was increased compared to Examples 1-3 and Example 5.

[0097] On the other hand, Comparative Example 2 used a separation-wall type distillation column instead of a general distillation column like in the example, and it was confirmed that it had the highest impurity content.

Claims

1. The steps include supplying a circulating stream containing unreacted olefin comonomers and residual solvent, a solvent stream containing solvent, and a comonomer stream containing olefin comonomers to a distillation column, The steps include obtaining an upper discharge stream of the distillation column containing low-boiling-point components, a lower discharge stream of the distillation column containing high-boiling-point components, and a side discharge stream of the distillation column containing an olefin copolymer and a solvent by distillation performed in the aforementioned distillation column, The steps include supplying the side discharge stream of the distillation column and the monomer stream containing the olefin monomer to a polymerization reactor and copolymerizing them to obtain a polymer reactor discharge stream containing an olefin-based elastomer solution, A method for producing an olefin elastomer, comprising the steps of supplying the discharge stream of a polymerization reactor containing the olefin elastomer solution to a flash drum to obtain an olefin elastomer.

2. The method for producing an olefin-based elastomer according to claim 1, wherein the circulating stream containing the unreacted olefin copolymer and residual solvent is derived from the stream separated from the olefin-based elastomer in the flash drum.

3. The method for producing an olefin-based elastomer according to claim 1, wherein the olefin monomer comprises one or more of ethylene and propylene.

4. The method for producing an olefin-based elastomer according to claim 1, wherein the olefin copolymer comprises 1-butene or 1-octene.

5. The method for producing an olefin-based elastomer according to claim 1, wherein the solvent comprises one or more of cyclohexane, methylcyclohexane, heptane, nonane, decane, toluene, benzene, and hexane.

6. The supply of the aforementioned circulation stream, solvent stream, and copolymer stream is as follows: The method for producing an olefin-based elastomer according to claim 1, wherein the circulation stream and solvent stream are mixed and supplied to the distillation column, and the copolymer stream is supplied directly to the distillation column.

7. Mixing the circulation stream and the solvent stream and supplying them to the distillation column is, The method for producing an olefin-based elastomer according to claim 6, wherein the mixed stream of the circulation stream and the solvent stream is supplied to the distillation column via a heat exchanger.

8. The method for producing an olefin-based elastomer according to claim 1, wherein the weight ratio of the solvent to the olefin comonomer contained in the side discharge stream of the distillation column is 1.28 to 1.

58.

9. The method for producing an olefin-based elastomer according to claim 1, wherein the side discharge stream of the distillation column is discharged from the side of the distillation column at a height of 60% to 77% from the top to the bottom.

10. The method for producing an olefin-based elastomer according to claim 1, wherein the weight flow rate ratio of the olefin comonomer to the olefin monomer supplied to the polymerization reactor is 0.8 to 1.

5.

11. The method for producing an olefin-based elastomer according to claim 1, wherein the temperature at the bottom of the distillation column is 120 to 180°C.

12. The pressure at the top of the aforementioned distillation column is 0.7 to 1.0 kg / cm². ２ A method for producing an olefin-based elastomer according to claim 1, wherein the amount is g.

13. The method for producing an olefin-based elastomer according to claim 1, wherein the upper reflux ratio of the flow rate of the upper reflux stream of the distillation column to the flow rate of the upper discharge stream of the distillation column is 60 to 75.

14. The method for producing an olefin-based elastomer according to claim 1, wherein the lower reflux ratio of the flow rate of the lower reflux stream of the distillation column to the flow rate of the lower discharge stream of the distillation column is 20 to 220.

15. The side discharge stream and monomer stream of the distillation column are supplied as follows: A method for producing an olefin-based elastomer according to claim 1, comprising mixing the side discharge stream of the distillation column and the monomer stream and supplying the mixture to the polymerization reactor.

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