Solvent cleaning method for preparing ethylene-acrylic acid copolymer

Abstract

The present invention relates to a method for preparing a vinyl copolymer, and more specifically, to a method for preparing a vinyl copolymer that can prevent corrosion and clogging of an apparatus and improve process efficiency. The method for preparing a vinyl copolymer of the present invention selectively performs one of a preparation mode and a cleaning mode, the preparation mode comprising: a) a step of compressing a mixture containing ethylene compressed once, a comonomer containing a carboxylic acid, and a polar solvent under high pressure to generate a compressed product; b) a step of reacting the compressed product to generate a reaction product containing a vinyl copolymer; and c) a step of separating and recovering unreacted residues from the reaction product and flowing the unreacted residues into the mixture of step a), the cleaning mode comprising: a step of supplying the compressed product generated in step a) as a mixture to step a) again without performing step b).

Description

Technical Field

[0001] The present invention relates to a method for preparing a vinyl copolymer, and more particularly, to a method for preparing a vinyl copolymer capable of removing and preventing plugging and corrosion of a device and improving process efficiency. Background Art

[0002] Vinyl copolymers are usually prepared in an autoclave reactor or a tubular reactor under ultra-high pressure by continuously introducing ethylene, one or more optional comonomers and one or more organic peroxide initiators usually diluted in an organic solvent.

[0003] In the prior art, as disclosed in Korean Patent Publication No. 10-2009-0019811, a method for preparing an ethylene copolymer, and Korean Patent Publication No. 10-2020-0023648, a high pressure polymerization method for preparing an ethylene copolymer, a carboxylic acid comonomer is used in preparing an ethylene copolymer.

[0004] However, the existing methods for preparing vinyl copolymers have various problems due to the use of comonomers having an acid group such as carboxylic acid. First, the acidity of the carboxylic acid comonomer causes corrosion problems, which leads to the problem of consuming process equipment maintenance costs. In addition, due to the high reactivity and self-polymerization of carboxylic acid, blockage occurs in the process line, requiring frequent process interruptions and maintenance, thereby reducing process efficiency.

[0005] [Prior art literature]

[0006] [Patent Document]

[0007] (Patent Document 1): Korean Patent Publication No. 10-2009-0019811

[0008] (Patent Document 2): Korean Patent Publication No. 10-2020-0023648 Summary of the invention

[0009] Technical issues to be solved

[0010] The object of the present invention is to provide a method for preparing a vinyl copolymer, which can prevent and eliminate corrosion and blockage of a vinyl copolymer preparation device and improve process efficiency.

[0011] Technical Solution

[0012] The method for preparing an ethylene copolymer of the present invention selectively performs one of a preparation mode and a cleaning mode, wherein the preparation mode includes: a) a step of compressing a mixture containing ethylene compressed once, a comonomer containing a carboxylic acid, and a polar solvent under high pressure to produce a compressed product; b) a step of reacting the compressed product to produce a reaction product containing an ethylene copolymer; and c) a step of separating and recovering an unreacted residue from the reaction product and making it flow into the mixture of step a), wherein the cleaning mode includes: a step of supplying the compressed product produced in step a) as a mixture to step a) again without performing step b).

[0013] In the method for preparing an ethylene copolymer according to one embodiment of the present invention, in the preparation mode, the mixture of step a) may contain 1-10 parts by weight of the carboxylic acid-containing comonomer and 1-10 parts by weight of the polar solvent relative to 100 parts by weight of the ethylene compressed once.

[0014] In the method for preparing an ethylene copolymer according to one embodiment of the present invention, in the cleaning mode, the mixture of step a) may contain 1-20 parts by weight of the carboxylic acid-containing comonomer and 1-20 parts by weight of the polar solvent relative to 100 parts by weight of the ethylene compressed once.

[0015] In the preparation method of the vinyl copolymer according to one embodiment of the present invention, the polar solvent can be selected from one or more of methyl alcohol, ethanol, isopropyl alcohol, methyl ethyl ketone, tetrahydrofuran, acetone, ethylacetate, propyl acetate, butyl acetate, 2-methoxyethanol and 2-ethoxyethanol.

[0016] In the method for preparing the ethylene copolymer according to one embodiment of the present invention, the preparation mode may further include: d) separating and recovering the remaining unreacted residue from the reaction product of separating the unreacted residue in step c) and flowing it into the ethylene in step a).

[0017] In the method for preparing an ethylene-based copolymer according to an embodiment of the present invention, the cleaning mode may further include a step of separating impurities from the compressed product before the compressed product is supplied to the step a) again.

[0018] The method for preparing a vinyl copolymer according to an embodiment of the present invention may further include a discharge mode for discharging the impurities, and one of the preparation mode, the cleaning mode, and the discharge mode may be selectively performed.

[0019] The preparation device of the ethylene copolymer of the present invention comprises: a primary compressor for once compressing ethylene supplied by a first supply part; a high-pressure compressor for secondarily compressing a mixture containing the once compressed ethylene, a comonomer containing carboxylic acid supplied by a second supply part, and a polar solvent; a supply pipeline for supplying the compressed product compressed by the high-pressure compressor to a reactor; a high-pressure separator for once filtering the reaction product discharged from the reactor to separate unreacted residues; a high-pressure circulation pipeline for supplying the unreacted residues separated from the high-pressure separator to the front end of the high-pressure compressor; a bypass pipeline for connecting the rear end of the high-pressure compressor and the high-pressure circulation pipeline; and a control unit for selectively conveying the compressed product to the supply pipeline or the bypass pipeline according to a preparation mode and a cleaning mode.

[0020] In the ethylene copolymer preparation device of one embodiment of the present invention, the control unit can be configured to: in the preparation mode, supply the compressed product to the reactor through the supply pipeline; in the cleaning mode, transport the compressed product to the high-pressure circulation pipeline through the bypass line.

[0021] In the preparation device of the vinyl copolymer of one embodiment of the present invention, the bypass line is arranged in the supply line through a main valve branch, and the supply line is provided with a first supply line connecting the high-pressure compressor and the main valve and a second supply line connecting the main valve and the reactor. The control unit can be configured as follows: in the preparation mode, the main valve is opened and closed to open the first supply line and the second supply line, thereby supplying the compressed material to the reactor; in the cleaning mode, the main valve is opened and closed to open the first supply line and the bypass line, thereby transporting the compressed material to the high-pressure circulation line.

[0022] The device for preparing the vinyl copolymer according to one embodiment of the present invention may further include a filtering section, which is located at the rear end of the high-pressure circulation pipeline and can filter and remove impurities.

[0023] The preparation device of the vinyl copolymer according to one embodiment of the present invention may also include: a low-pressure separator, which performs secondary filtration on the reaction product discharged from the high-pressure separator and discharges a final product in which the remaining unreacted residue is separated from the reaction product; and a low-pressure circulation pipeline, which supplies the unreacted residue separated from the low-pressure separator to the front end of the primary compressor.

[0024] Beneficial Effects

[0025] The method for preparing the vinyl copolymer of the present invention can prevent corrosion caused by carboxylic acid and clogging due to self-polymerization by supplying a mixture of a comonomer containing carboxylic acid and a polar solvent in a preparation mode and a cleaning mode.

[0026] Furthermore, clogging occurring in the process of preparing the ethylene copolymer can be cleaned by the cleaning mode, thereby increasing the life of the process equipment, and removing the clogging without interrupting and restarting the high pressure equipment, thereby improving the productivity and efficiency of the process. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is a schematic diagram showing an apparatus for preparing an ethylene copolymer according to one embodiment of the present invention. DETAILED DESCRIPTION

[0028] Unless otherwise defined, the technical and scientific terms used in this specification have the same meanings as those generally understood by technicians in the technical field to which the invention belongs, and descriptions of well-known functions and structures that may unnecessarily obscure the main purpose of the invention are omitted in the following description and drawings.

[0029] Furthermore, unless otherwise mentioned, a singular form used in the present specification may also include a plural form.

[0030] In addition, the units used in this specification without special mention are based on weight. As an example, the unit of % or ratio refers to weight % or weight ratio. Unless otherwise specified, weight % refers to the weight % of a certain ingredient in the total composition.

[0031] In addition, the numerical range used in this specification includes the lower limit value and the upper limit value and all values ​​within the range, the increments logically derived from the form and width of the defined range, all values ​​defined therein, and all possible combinations of the upper and lower limits of the numerical range defined in different forms. Unless otherwise defined, the values ​​outside the numerical range that may be generated in the specification of the present invention due to experimental errors or rounding of numerical values ​​are also included in the defined numerical range.

[0032] The terms "comprising" or "including" in this specification are open-ended records with equivalent meanings to expressions such as "having", "containing", "having" or "characterized by", and do not exclude elements, materials or processes that are not further listed.

[0033] The term "reaction product" herein refers to a product that has undergone ethylene polymerization reaction in a reactor in a process for preparing a vinyl copolymer, and may include the vinyl copolymer and unreacted residues.

[0034] The term "unreacted residue" in the present specification refers to the remaining substances other than the vinyl copolymer in the vinyl copolymer preparation process, specifically, it may include unreacted ethylene, carboxylic acid, polar solvent, other additives and initiator.

[0035] The method for preparing an ethylene copolymer of the present invention selectively performs one of a preparation mode and a cleaning mode, wherein the preparation mode includes: a) a step of compressing a mixture containing ethylene compressed once, a comonomer containing a carboxylic acid, and a polar solvent under high pressure to produce a compressed product; b) a step of reacting the compressed product to produce a reaction product containing an ethylene copolymer; and c) a step of separating and recovering an unreacted residue from the reaction product and making it flow into the mixture of step a), wherein the cleaning mode includes: a step of supplying the compressed product produced in step a) as a mixture to step a) again without performing step b).

[0036] In the prior art, various problems occur in the preparation method of vinyl copolymers due to the use of comonomers containing acid groups such as carboxylic acids. First, due to the acidity of the comonomers containing carboxylic acids, corrosion problems occur, and there is a problem of consuming process equipment maintenance costs. In addition, due to the high reactivity and self-polymerization of the comonomers containing carboxylic acids, there is a problem of blockage in the process line and the device. Therefore, in order to clean the device, it is necessary to frequently interrupt the process and perform maintenance, so the process efficiency is reduced. Especially, in the case of a high-pressure compressor (Hyper compressor), it is necessary to consume a lot of time and cost in order to restart.

[0037] The method for preparing a vinyl copolymer of the present invention can prevent corrosion caused by the comonomer containing carboxylic acid and self-polymerization of the comonomer containing carboxylic acid, and prevent clogging while preparing the vinyl copolymer by selectively supplying a preparation mode and a cleaning mode containing a mixture of the comonomer containing carboxylic acid and a polar solvent.

[0038] Specifically, the preparation mode is a mode in which a mixture of a polar solvent having a cleaning function and a comonomer is reacted with ethylene to prepare a vinyl copolymer. In the preparation process of the vinyl copolymer, clogging in the preparation device can be suppressed by preventing corrosion caused by the comonomer and self-polymerization of the comonomer.

[0039] Furthermore, the cleaning mode is a mode for cleaning the inside of the production device when a blockage occurs in the production device, and is a mode in which the mixture of the mixed polar solvent and the comonomer is supplied to the inside of the production device and circulated to clean the inside of the production device without reacting ethylene. By cleaning the blockage in such a cleaning mode, the life of the process device can be increased.

[0040] In one embodiment of the present invention, it may be a preparation method using a preparation device for vinyl copolymers, the preparation device for vinyl copolymers comprising: a supply section, which compresses a mixture of ethylene, a comonomer containing a carboxylic acid and a polar solvent compressed once by a primary compressor with a high-pressure compressor and supplies it to a reactor; a circulation section, which filters the reaction product discharged from the reactor and supplies the unreacted residue separated from the reaction product to the front end of the high-pressure compressor; and a bypass section, which connects the supply section and the circulation section and conveys the compressed product compressed by the high-pressure compressor to the circulation section. At this time, the preparation device can be operated in a preparation mode in which the compressed product compressed by the high-pressure compressor is supplied to the reactor through the supply section or in a cleaning mode in which the compressed product compressed by the high-pressure compressor is supplied to the circulation section through the bypass section.

[0041] In detail, the preparation mode may include: a step of supplying a mixture comprising ethylene, a comonomer containing a carboxylic acid, and a polar solvent which is compressed once by a primary compressor to a high-pressure compressor to form a compressed product; a step of supplying the compressed product to a reactor through a supply section to generate a reaction product; a step of supplying the reaction product discharged from the reactor to a circulation section; and a step of supplying an unreacted residue separated from the reaction product supplied to the circulation section to a front end of the high-pressure compressor.

[0042] In the preparation mode, the compressed product supplied to the reactor reacts in the reactor, so that the vinyl copolymer can be prepared. In addition, ethylene and comonomers are supplied to the high-pressure compressor together with the polar solvent, so that even if the comonomer is present, the blockage of the high-pressure compressor can be prevented. In addition, the compressed product (ethylene, comonomer and polar solvent) compressed in the high-pressure compressor is supplied to the circulation part through the reactor, and the unreacted ethylene and polar solvent are supplied to the front end of the high-pressure compressor again, so in the whole preparation process, it can have the effect of preventing corrosion caused by the polar solvent and inhibiting the occurrence of blockage.

[0043] The cleaning mode may include: a step of supplying the compressed material to the circulation part through a bypass part; and a step of supplying the compressed material supplied to the circulation part to the front end of the high-pressure compressor. In the cleaning mode, the compressed material does not pass through the reactor, is transported to the circulation part through the bypass part, and is supplied to the high-pressure separator. Therefore, the blockage can be removed without interrupting and restarting the high-pressure device (high-pressure separator), so the productivity and efficiency of the process can be improved. In addition, the cleaning mode can be performed by taking advantage of the opportunity of the process stopping operation, and by removing foreign matter accumulated in the process, accidents caused by this can be prevented in advance.

[0044] In one embodiment of the present invention, the preparation mode may further include the step of d) separating and recovering the remaining unreacted residue from the reaction product of the step c) and making it flow into the ethylene of the step a).

[0045] Specifically, the above-mentioned preparation device of the vinyl copolymer may further include a low-pressure circulation unit, which performs secondary filtration on the reaction product supplied to the circulation unit, discharges a final product of separating the residual unreacted residue from the reaction product, and supplies the separated residual unreacted residue to a primary compressor, and the preparation mode may be performed by such a preparation device. At this time, the preparation mode may further include the steps of supplying the reaction product of the separated unreacted residue to the low-pressure circulation unit, separating the residual unreacted residue from the reaction product, and supplying the separated residual unreacted residue to the front end of the primary compressor.

[0046] The method for preparing vinyl copolymers also includes such a preparation mode. Since the polar solvent can be transported to the front end of the primary compressor that supplies ethylene, the polar solvent is transported throughout the entire preparation device, which can inhibit the occurrence of blockage and remove various foreign matter remaining inside the preparation device.

[0047] In addition, in one embodiment of the present invention, the preparation device of the above-mentioned ethylene copolymer may further include a filter section arranged in the circulation section, in which case the impurities of the compressed material can be removed by the filter section in the cleaning mode. In the cleaning mode, the steps of supplying the compressed material to the circulation section through the bypass section and the step of supplying the compressed material to the front end of the high-pressure compressor again through the circulation section may be used as a unit process, and may be repeated more than 2 times if necessary. Therefore, impurities in the compressed material can be easily removed without interrupting the process, and the device can be cleaned more cleanly. When the cleaning mode is repeatedly performed, the amount of ethylene and the mixture corresponding to the amount of impurities removed can be resupplied to the front end of the high-pressure compressor, so that a certain amount of compressed material can be circulated in the process.

[0048] In one embodiment of the present invention, the preparation method of vinyl copolymer can also include a discharge mode for discharging impurities separated during the cleaning mode, and can selectively perform one of the preparation mode, the cleaning mode and the discharge mode. At this time, in the discharge mode, impurities can be discharged to the outside through a filter portion arranged in a high-pressure circulation portion. In the discharge mode, impurities removed from the process inside during the cleaning mode can be discharged, that is, blockage can be finally discharged. In addition, the remaining impurities except unreacted ethanol and polar solvent in the unreacted residue supplied to the high-pressure compressor through the circulation portion during the preparation mode can also be removed.

[0049] In addition, when clogging occurs due to excessive impurities in the filter part, an additional line can be provided to perform a discharge mode in the filter part in an operating state or a non-operating state such as in the preparation mode and the cleaning mode, thereby cleaning the inside of the filter part.

[0050] In one embodiment of the present invention, in the preparation mode, the mixture of step a) may contain 1-10 parts by weight of a comonomer containing a carboxylic acid and 1-10 parts by weight of a polar solvent, specifically, 3-7 parts by weight of a comonomer containing a carboxylic acid and 3-7 parts by weight of a polar solvent, relative to 100 parts by weight of ethylene. In the preparation mode, within the above range, the effect of preventing blockage can be obtained without reducing the yield of ethylene, but it is not limited thereto.

[0051] In one embodiment of the present invention, in the cleaning mode, the mixture of step a) contains 1-20 parts by weight of a comonomer containing a carboxylic acid and 1-20 parts by weight of a polar solvent relative to 100 parts by weight of ethylene. Specifically, the mixture may contain 3-10 parts by weight of a comonomer containing a carboxylic acid and 3-10 parts by weight of a polar solvent relative to 100 parts by weight of ethylene. In the cleaning mode, within the above range, the blockage cleaning rate may be increased, but is not limited thereto.

[0052] In the preparation mode and the cleaning mode, the contents of ethylene, carboxylic acid-containing comonomers and polar solvents in the mixture of step a) in each mode may be the same. As a specific example, in the preparation mode, the mixture of step a) may contain 90w% of ethylene, 5w% of carboxylic acid-containing comonomers and 5w% of polar solvents, and in the cleaning mode, the mixture of step a) may also contain 90w% of ethylene, 5w% of carboxylic acid-containing comonomers and 5w% of polar solvents.

[0053] Different from this, in the cleaning mode, the amount of polar solvent can be greater than that in the preparation mode to improve the blockage cleaning rate. As a specific example, in the preparation mode, the mixture contains 90w% ethylene, 5w% comonomer containing carboxylic acid and 5w% polar solvent, and in the cleaning mode, the mixture can contain 85w% ethylene, 5w% comonomer containing carboxylic acid and 10w% polar solvent.

[0054] The carboxylic acid may be any one or more monomers selected from acrylic acid, methacrylic acid, maleic anhydride and maleic acid, but is not limited thereto. All comonomers used in the preparation of existing vinyl copolymers are applicable.

[0055] The polar solvent may be a low boiling point polar solvent, specifically, may be one or more selected from methanol, ethanol, isopropanol, methyl ethyl ketone, tetrahydrofuran, acetone, ethyl acetate, propyl acetate, butyl acetate, 2-methoxyethanol and 2-ethoxyethanol. Such a polar solvent can prevent corrosion caused by the carboxylic acid comonomer and can show an excellent clogging cleaning effect.

[0056] The preparation mode, the cleaning mode and the discharge mode can be selectively executed by the control unit. As a specific example, the axial position of the plunger part of the high-pressure compressor in the preparation mode can be monitored, and the cleaning mode can be executed when the axial position of the plunger deviates from the standard setting value due to blockage. Alternatively, the cleaning mode can be executed by sensing the temperature change caused by the friction of the plunger part according to the change of the axial position of the plunger part.

[0057] When switching from the cleaning mode to the preparation mode, the cleaning mode may also be executed by sensing the axial position and temperature change of the plunger.

[0058] Figure 1 FIG. 4 is a schematic diagram of a device for preparing a vinyl polymer according to an embodiment of the present invention.

[0059] Reference Figure 1The preparation device of the ethylene polymer of the present invention includes: a primary compressor 30, which once compresses ethylene supplied by the first supply part 10; a high-pressure compressor 50, which secondarily compresses a mixture containing the once compressed ethylene, a comonomer containing carboxylic acid supplied by the second supply part 15, and a polar solvent; a supply pipeline 20, which supplies the compressed product compressed by the high-pressure compressor 50 to the reactor 70; a high-pressure separator 90, which once filters the reaction product discharged from the reactor 70 to separate unreacted residues; a high-pressure circulation pipeline 40, which supplies the unreacted residues separated from the high-pressure separator 90 to the front end of the high-pressure compressor 50; a bypass line 60, which connects the rear end of the high-pressure compressor 50 and the high-pressure circulation pipeline 40; and a control unit (not shown), which selectively transports the compressed product to the supply pipeline 20 or the bypass pipeline 60 according to the preparation mode and the cleaning mode.

[0060] In the case of existing vinyl polymer preparation equipment, when blockage occurs in the equipment, the operation is stopped and then restarted after cleaning. Therefore, a lot of time is consumed due to the long restart time required for equipment such as the high-pressure compressor 50, thereby greatly reducing the process efficiency.

[0061] The preparation device of the present invention can selectively deliver the compressed material with cleaning function to the supply line or the bypass line according to the preparation mode and the cleaning mode, so the blockage inside the device can be effectively removed without interrupting and restarting the high-pressure device (high-pressure compressor).

[0062] In the present invention, the primary compressor 30 (primary compressor), the high-pressure compressor 50 (Hypercompressor), the reactor 70 (Autoclave Reactor), the high-pressure separator 90 (High pressure separator, HPS) and the low-pressure separator (Low pressure separator, LPS) are used in the existing vinyl polymer preparation equipment, so the detailed description is omitted.

[0063] Specifically, the control unit is configured to supply the compressed product to the reactor 70 through the supply line 20 in the production mode, and to deliver the compressed product to the high-pressure circulation line 40 through the bypass line 60 in the cleaning mode. Therefore, the compressed product can be reacted to produce an ethylene polymer as a final product in the production mode, and blockage can be removed without interrupting and restarting the high-pressure device (high-pressure compressor 50) in the cleaning mode, thereby improving the productivity and efficiency of the process.

[0064] Specifically, the bypass line 60 connecting the rear end of the high-pressure compressor 50 and the high-pressure circulation line 40 can be set in the supply line 20 through the main valve 25 branch, and the supply line 20 connecting the high-pressure compressor 50 and the reactor 70 and supplying the compressed product compressed by the high-pressure compressor 50 to the reactor 70 can be provided with a first supply line 21 connecting the high-pressure compressor 50 and the main valve 25 and a second supply line 23 connecting the main valve 25 and the reactor 70. At this time, the control unit can be configured to: in the preparation mode, open and close the main valve 25 so that the first supply line 21 and the second supply line 23 are opened, thereby conveying the compressed product to the reactor 70, and in the cleaning mode, open and close the main valve 25 so that the first supply line 21 and the bypass line 60 are opened, thereby conveying the compressed product to the high-pressure circulation line. The control unit is configured to enable the process management personnel to selectively execute the preparation mode and the cleaning mode only by opening and closing the main valve 25.

[0065] In one embodiment of the present invention, a filter unit 41 may be further included, which is located at the rear end of the high-pressure circulation pipeline 40 and can filter and remove impurities. In the preparation mode, the filter unit 41 can remove the remaining impurities except unreacted ethanol and polar solvent from the unreacted residue supplied to the high-pressure compressor 50 through the high-pressure circulation pipeline 40. In the cleaning mode, the filter unit 41 can filter the blockages transported through the circulation pipeline and discharge them to the outside of the device, so that the inside of the device can be kept clean.

[0066] In one embodiment of the present invention, a low-pressure separator 95 and a low-pressure circulation line 97 may be further included. The low-pressure separator 95 performs secondary filtration on the reaction product discharged from the high-pressure separator 90, that is, the reaction product from which the unreacted residue is separated by the primary filtration, and discharges a final product (A) in which the remaining unreacted residue is separated from the reaction product. The low-pressure circulation line 97 supplies the unreacted residue separated from the low-pressure separator 95 to the front end of the primary compressor 30. The low-pressure separator and the low-pressure circulation line remove the unreacted residue again, so that a high-purity ethylene polymer can be prepared. Since the unreacted residue containing ethylene and the polar solvent is supplied to the primary compressor 30 side, the blockage of the entire device can be cleaned, so that when preparing an ethylene polymer by such a preparation device, high process efficiency can be achieved.

[0067] [Example 1] Preparation mode

[0068] Ethylene (Dow Chemical Company (DOW)) which was once compressed in a primary compressor at a temperature of 30° C. and a pressure of 200 bar was heated at 3 m 3 / min was supplied to the secondary compressor, and a mixture of acrylic acid (Acrylic Acid, Arkema) and ethyl acetate (Ethyl Acetate, Quimidroga) in a weight ratio of 7:1 was added at 0.004 m 3 / min average flow rate is supplied to the secondary compressor. After that, the secondary pressure is applied at a temperature of 20°C and a pressure of 200 bar. At this time, the main valve is opened by the control unit so that the first supply line and the second supply line are opened. The compressed compress and initiator (tert-Butyl Peroxyacetate, tert-Butyl peroxy-2-ethylhexanoate) are added at 0.4m 3 The reaction was carried out in the reactor at a reaction temperature of 250°C and a pressure of 2250 bar. Afterwards, the reaction product discharged from the reactor was discharged at a rate of 1.3 m 3 The unreacted residue separated by the high pressure separator is supplied to the high pressure separator at an average flow rate of 1.4 m / min. 3 The average flow rate of / min is supplied to the secondary compressor again, and the reaction product from which the unreacted residue is removed once by the high-pressure separator is supplied to the low-pressure separator for the second removal of the unreacted residue. The unreacted residue removed in the low-pressure separator is 5.0m 3 The average flow rate of / min is again supplied to the primary compressor, and the final product from which the unreacted residue is removed in the low-pressure separator is produced at 2500kg / hour.

[0069] [Example 2] Cleaning Mode

[0070] In the preparation mode of Example 1, the temperature of the plunger portion of the high-pressure compressor is sensed to be 80° C. or higher, and thus the cleaning mode is performed.

[0071] Ethylene (DOW) which was once compressed in a primary compressor at a temperature of 30° C. and a pressure of 200 bar was heated to 0.1 m 3 The average flow rate of / min was supplied to the secondary compressor. A mixture of acrylic acid (Arkema) and ethyl acetate in a weight ratio of 7:1 was added at 0.01m 3 / min average flow rate is supplied to the secondary compressor. After that, the secondary pressure is applied at a temperature of 20°C and a pressure of 200 bar. At this time, the main valve is opened by the control unit so that the first supply line and the bypass line are opened (the second supply line is closed). The compressed compressed material is 0.8m 3 The average flow rate of / min is supplied to the circulation line and thus to the secondary compressor. This cleaning mode is carried out for about 12 hours.

[0072] [Comparative Example 1]

[0073] The same method as in Example 1 was performed except that ethyl acetate was used as the polar solvent.

[0074] When the processes of Examples 1 to 2 and the comparative example are performed, the efficiency of the heat exchanger and the compression efficiency of the high-pressure compressor are evaluated to determine whether the clogging is removed. The results are shown in Table 1 below. Referring to Table 1, it can be confirmed that the heat exchanger and the high-pressure compressor of the present invention are excellent in efficiency. That is, it can be confirmed that the occurrence of clogging is suppressed in the entire process.

[0075] [Table 1]

[0076]

[0077] As described above, the present invention is illustrated through specific contents and limited embodiments and drawings, but this is only provided to help a more comprehensive understanding of the present invention. The present invention is not limited to the above embodiments, and ordinary technicians in the field to which the present invention belongs can make various modifications and deformations through such descriptions.

[0078] Therefore, the concept of the present invention should not be limited to the described embodiments, and the claims of the present invention and all contents that are equivalent to the claims or have equivalent variations belong to the scope of the concept of the present invention.

Claims

1. A method for preparing a vinyl copolymer, comprising a preparation mode and a cleaning mode, wherein: The preparation mode includes: a) subjecting a mixture comprising ethylene compressed once, a comonomer containing a carboxylic acid and a polar solvent to high pressure compression to produce a compressed product, wherein the polar solvent is selected from one or more of methanol, ethanol, isopropanol, methyl ethyl ketone, tetrahydrofuran, acetone, ethyl acetate, propyl acetate, butyl acetate, 2-methoxyethanol and 2-ethoxyethanol; b) a reaction step of reacting the compressed product to produce a reaction product comprising an ethylene copolymer; and c) a step of separating and recovering unreacted residues from the reaction product and allowing the unreacted residues to flow into the mixture of step a), The cleaning mode includes the step of supplying the compressed product produced in the step a) as a mixture again to the step a) without performing the step b).

2. The method for preparing the vinyl copolymer according to claim 1, wherein: In the preparation mode, the mixture of step a) comprises 1-10 parts by weight of the carboxylic acid-containing comonomer and 1-10 parts by weight of the polar solvent relative to 100 parts by weight of the once compressed ethylene.

3. The method for preparing the vinyl copolymer according to claim 1, wherein: In the cleaning mode, the mixture of step a) comprises 1-20 parts by weight of the carboxylic acid-containing comonomer and 1-20 parts by weight of the polar solvent relative to 100 parts by weight of the once compressed ethylene.

4. The method for preparing the vinyl copolymer according to claim 1, wherein: The preparation mode also includes: d) a step of separating and recovering the remaining unreacted residue from the reaction product of the step c) and allowing the unreacted residue to flow into the ethylene of the step a).

5. The method for preparing the vinyl copolymer according to claim 1, wherein: The cleaning mode also includes: A step of separating impurities from the compressed product before supplying the compressed product to the step a) again.

6. The method for preparing the vinyl copolymer according to claim 5, further comprising: A discharge mode for discharging said impurities.

7. A device for preparing a vinyl copolymer, which is used in the method for preparing a vinyl copolymer according to claim 1, and comprises: A primary compressor for performing primary compression on the ethylene supplied by the first supply part; A high-pressure compressor for secondary compression of a mixture comprising the primary compressed ethylene, a comonomer containing a carboxylic acid supplied from a second supply part, and a polar solvent; a supply line for supplying a compressate compressed by the high-pressure compressor to a reactor; A high-pressure separator for filtering the reaction product discharged from the reactor to separate unreacted residues; A high-pressure circulation pipeline, supplying the unreacted residue separated from the high-pressure separator to the front end of the high-pressure compressor; A bypass pipeline connecting the rear end of the high-pressure compressor and the high-pressure circulation pipeline; as well as The control unit selectively delivers the compressed material to the supply line or the bypass line according to a preparation mode and a cleaning mode.

8. The device for producing vinyl copolymer according to claim 7, wherein: The control unit is configured as follows: In the preparation mode, the compressed material is supplied to the reactor through the supply line, In the cleaning mode, the compressed material is transported to the high-pressure circulation line through the bypass line.

9. The device for producing vinyl copolymer according to claim 7, wherein: The bypass line is arranged in the supply line through a main valve branch, The supply pipeline is provided with a first supply pipeline connecting the high-pressure compressor and the main valve and a second supply pipeline connecting the main valve and the reactor. The control unit is configured as follows: In the preparation mode, the main valve is opened and closed to open the first supply line and the second supply line, thereby supplying the compressed material to the reactor. In the cleaning mode, the main valve is opened and closed to open the first supply line and the bypass line, thereby delivering the compressed material to the high-pressure circulation line.

10. The device for preparing the vinyl copolymer according to claim 7, further comprising: The filter unit is located at the rear end of the high-pressure circulation pipeline and filters the compressed material.

11. The device for preparing the vinyl copolymer according to claim 7, further comprising: A low-pressure separator, located at the rear end of the high-pressure separator, performs secondary filtration on the reaction product discharged from the high-pressure separator, and discharges a final product obtained by separating the remaining unreacted residue from the reaction product; as well as The low-pressure circulation pipeline supplies the unreacted residue separated from the low-pressure separator to the front end of the primary compressor.

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