Continuous solution polymerization method and system

Abstract

The present invention provides a continuous solution polymerization method and system. Such a continuous solution polymerization method includes subjecting raw materials to a polymerization reaction to obtain a polymer solution, mixing the polymer solution with a complexing agent and reacting them, washing the resulting mixture with water to obtain a polymer solution after demetallization, and obtaining polymer particles after devolatilization or extrusion granulation of the polymer solution after demetallization. Such a continuous solution polymerization system includes a polymerization reaction unit, a demetallization unit, a devolatilization unit, an extrusion granulation unit, etc. The method and system of the present invention have the advantages that they can efficiently remove metals remaining in the polymer, have a short process, low production costs, and can operate continuously for a long period.

Description

Technical Field

[0001] The present invention relates to a continuous solution polymerization method and system, and belongs to the technical field of solution polymerization.

Background Art

[0002] Metallocene catalysts have been the focus of research in organometallic chemistry, catalytic chemistry, polymer chemistry, and materials science in recent decades. By using such catalysts, olefin polymers with a narrow molecular weight distribution and a uniform chemical composition distribution can be obtained, and by adjusting the structure of the catalyst, the molecular structure and molecular weight of the polymer can be highly controlled. Industrially high-performance polymers produced using metallocene catalysts mainly include polyolefin elastomers (POE), polyolefin plastomers (POP), cycloolefin copolymers (COC), cycloolefin polymers (COP), etc. Among them, cycloolefin copolymers have excellent heat resistance, chemical resistance, high toughness, UV-Vis transparency, and extremely low hygroscopicity and extractability, and can be used as optical memory media, pharmaceutical packaging materials, etc.

[0003] Currently, in the industry, the production of polyolefin products is often carried out using an efficient metallocene olefin polymerization catalyst system. Usually, metallocene catalysts contain elements of groups IVB, VB, and VIB of the periodic table, especially vanadium, titanium, and zirconium, and the cocatalysts mainly contain elements such as aluminum. Such catalysts are generally called transition metal catalysts and have high olefin polymerization catalytic activity. However, after the polymerization is completed, the metal in the catalyst remains in the polyolefin product, which has an adverse effect on the appearance expression, dielectric properties, optical performance, medical material performance, etc. of the final product. Therefore, for polyolefin products, especially high-grade polyolefin products such as medical grades and optical grades, how to efficiently remove the residual metal (abbreviated as demetallization or deashing) is the most important.

[0004] In the process of polymer industrialization, the commonly used ash removal methods mainly include aqueous phase extraction method, coagulation sedimentation method and complexation adsorption method. Among them, the complexation adsorption method is the most commonly used ash removal method in polymer industrial production, which has the advantages of simple process, large adsorption capacity, high removal efficiency, few interference factors and good stability. Complexing agents are roughly classified into two types: inorganic and organic. Inorganic complexing agents are usually easy to decompose at high temperatures and are only applicable to alkaline media, so their application scope is limited. Although organic complexing agents have a wide application range, it is usually difficult to reduce the metal content in the polymer solution to less than 10 ppm. In addition, in the industrialization process, complexation and ash removal are generally carried out using a supported adsorbent filler. Such an adsorbent is a solid filler produced by immersing and roasting an alumina carrier and a complexing agent material, and the effective loading amount of the complexing agent is low, which has certain limitations in application.

[0005] CN107011485A discloses a composite catalyst having three active centers and a method for producing a cycloolefin copolymer using the same. The method for producing the cycloolefin copolymer is carried out in a batch polymerization reaction tank using a composite catalyst (i.e., the main catalyst) having salicylic acid 2-mercaptoaniline titanium trichloride, racemic-vinyl (diindenyl) zirconium dichloride and dichlorozirconocene as three active centers, and a toluene solution of methylaluminoxane (MAO) as a cocatalyst, using cycloolefin as a comonomer, adding ethylene by supplementary metering during the polymerization process, controlling the pressure at 0.1 MPa, and carrying out the polymerization reaction. After the reaction is completed, the reaction solution is put into ethanol (consisting of 150 mL of hydrochloric acid and 1000 mL of ethanol) containing 15% (v / v%) hydrochloric acid for precipitation, then filtered, the filter cake is washed with ethanol (300 mL), and then dried to a constant weight to obtain a cycloolefin copolymer. However, this production method is not related to the removal of metals in the polymer.

[0006] CN108752526A discloses a catalyst system for producing ethylene and / or α-olefin and cycloolefin copolymer. The catalyst system includes a main catalyst and a cocatalyst. The main catalyst is a metallocene compound, and the cocatalyst is an organoboron compound and an alkylaluminum. The method for producing ethylene and / or α-olefin and cycloolefin copolymer by the catalyst system includes the steps of putting an inert organic solvent, ethylene / α-olefin and cycloolefin into a reactor respectively under the conditions of a temperature of 40-100 °C and a pressure of 1-30 bar, dissolving ethylene and / or α-olefin into the inert organic solvent until saturation, and then sequentially adding a triisobutylaluminum solution, a metallocene catalyst solution and an organoboron compound solution to carry out a polymerization reaction. Using the cocatalyst can polymerize the cycloolefin copolymer more efficiently than MAO, MMAO and dMAO, reduce the metal content in the polymerization product, and greatly reduce the post-treatment cost.

[0007] CN103374089A discloses a method for removing a catalyst from an ethylene-α-olefin copolymer solution. The copolymer solution contains an ethylene-α-olefin copolymer, an organic solvent and a catalyst. The catalyst includes an alkylaluminum cocatalyst and a vanadium compound main catalyst. This method includes: (1) contacting water with the copolymer solution to obtain a first mixture; (2) adjusting the pH value of the first mixture obtained in step (1) to 4-9 with a pH adjuster to obtain a second mixture; (3) performing centrifugation to separate and remove the precipitate from the second mixture obtained in step (2), wherein the addition amount of the water is 0.1-20% by volume based on the volume of the copolymer solution. This method has a remarkable effect of removing the residual catalyst in the copolymer solution and has a low cost. The pH adjuster used in this method is a hydroxide of an alkali metal and / or a hydroxide of an alkaline earth metal, preferably sodium hydroxide. This method does not have a sufficiently high metal removal rate, and the produced polymer product cannot meet the polymer index requirements of medical grade and optical grade.

[0008] US4716207A discloses a method for producing a nodular polymer by preparing a copolymer chain and coupling it with a coupling agent. The ash removal process in this method mainly involves supplying the copolymer product from the reactor to the ash removal section through a conduit, where the catalyst residue reacts with water to form a hydroxide insoluble in hydrocarbons, and then extracting the hydroxide with dilute acid to remove vanadium and aluminum compound residues. However, this method does not have a sufficient metal removal rate, and the produced polymer products cannot meet the polymer index requirements of medical grade and optical grade.

[0009] CN110016092A discloses a method for continuously producing polyolefins, especially polyolefin elastomers or mixtures thereof. This method performs prepolymerization using a tank reactor, which has the effect of improving the viscosity of the reaction system and facilitating the operation of the subsequent screw reactor. Also, static mixing polymerization is carried out using a static mixer to continuously increase the viscosity of the system and extend the reaction residence time. At the same time, extrusion polymerization is carried out using a reactive screw extruder to achieve a high conversion rate and the occurrence of a polymerization reaction at high viscosity. This method is suitable for the production of various polyolefins, especially suitable for the preparation of polyolefin elastomers or mixtures thereof. However, this method is not related to the removal of metals in the polymer, and the produced polymer products cannot meet the polymer index requirements of medical grade and optical grade.

[0010] CN113207283A discloses a system for solution polymerization. The system comprises a reactor system, a plurality of devolatilization vessels, and a liquid-liquid separator. The reactor system receives and reacts an antisolvent for lowering the lower critical solution temperature (LCST) of the system, a monomer, and a solvent, rather than a solvent for the polymer, to form a polymer. The plurality of devolatilization vessels are located downstream of the reactor system, receive a polymer solution from the reactor system, and each devolatilization vessel operates at a lower pressure than the previous one. The liquid-liquid separator receives a polymer solution from the reactor system and promotes the separation of the polymer and volatiles by lowering the pressure and temperature of the polymer solution in the liquid-liquid separator. However, the system does not relate to the process of removing metals in the polymer, and the manufactured polymer products cannot meet the polymer index requirements of medical grade and optical grade.

[0011] US20120088893A1 discloses a solution polymerization method. The method includes step (A) polymerizing one or more monomers in the presence of a solvent containing a heavy hydrocarbon solvent and a light hydrocarbon solvent to form a polymer solution; step (B) transferring the polymer solution to a liquid-liquid separator without heating the solution, and actively lowering the pressure of the polymer solution in a controlled manner before or within the liquid-liquid separator to induce the formation of at least two liquid phases, namely a polymer-rich phase and a solvent-rich phase, wherein the polymer concentration in the polymer-rich phase is higher than the polymer concentration in the polymer solution transferred to the liquid-liquid separator; and step (C) removing the solvent-rich phase. The solution polymerization process is mainly used to solve the problem of solvent separation in the polymer preparation process and does not relate to the process of demetallization.

[0012] US4992529A discloses a method for removing metals with a mixed acid. This method generates carboxylate salts that are insoluble in the organic phase through the reaction of a monocarboxylic acid with a metal in the organic phase, and generates inorganic salts that are soluble in the aqueous phase through the reaction of the carboxylate salts with the inorganic acid in the mixed acid. The carboxylic acid is reduced and returns to the organic phase again, and further reacts with the metal in the polymer solution to generate carboxylate salts. By repeating this process until the metal in the polymer solution completely transfers to the aqueous phase, the removal of residual metals is achieved. Here, the carboxylic acid acts as a phase transfer catalyst. Although the concept of this method is novel, the removal effect is not satisfactory, and a large amount of water is required.

[0013] CN114534694A discloses a complexing adsorption filler, its manufacturing method and use. The adsorption filler is a molecular sieve filler carrying a quinolinol compound, and an organic acid can be carried on the molecular sieve carrying the quinolinol compound. The adsorption filler can effectively remove the residual catalyst in the polyolefin solution, and has advantages such as a fast ash removal rate, a large adsorption capacity, and a small pressure loss, and is suitable for the removal of catalysts in various olefin solution polymerization processes. However, the manufacturing process of the adsorption filler is complex and cumbersome. At the same time, due to the low loading amount of quinolinol, the adsorption capacity of the adsorption filler is low and the operation cost is high.

[0014] CN114989331A discloses a method for complexing and deashing a polyolefin solution. The method includes: (1) adding dimazen to the polyolefin solution to complex and adsorb metal ions in the solution to form a complex; and (2) passing the polyolefin solution containing the complex through an adsorption column filled with a porous metal oxide for adsorption treatment to obtain a purified polyolefin solution. This deashing method can efficiently remove residual metals in the polyolefin solution, has a simple process, low filler swelling, low system pressure loss, a long service life of the deashing filler, a long exchange cycle of the adsorption column, and can significantly reduce the treatment cost. However, since dimazen has an ordinary complexing ability for metals, the metal removal rate is low, especially when the aluminum content in the polymer is high.

[0015] CN102875702A discloses a method for removing metals in a polymer. To achieve the purpose of removing residual metals in the latex, this method adopts a method of adding an organic base, such as n-butyllithium, phenyllithium, etc., to the polymer latex, adding an oxidizing agent, washing with water after the reaction, and finally centrifuging. This method has a high removal efficiency of residual metals in the polymer. However, since an organic base is used and some metal ions are introduced, the cost of raw material input and removal of residual catalysts is high, and the requirements for equipment due to the addition of the organic base are high.

[0016] CN114392724A discloses a dedicated deashing adsorbent for polyolefins, its manufacturing method and use. The deashing adsorbent is prepared by using pyridine-3-carboxylic acid as a complexing agent and supporting it on an oxide carrier. The deashing adsorbent can efficiently remove residual metals in the polyolefin solution, significantly reduce the residual metals in the polyolefin product, and has advantages such as a fast deashing rate, a large adsorption capacity, low swelling, and low solution pressure loss compared with the conventional chelating adsorption method. However, the manufacturing process of the deashing adsorbent is complex and cumbersome, and due to the low loading amount of pyridine-3-carboxylic acid, the adsorption capacity of the adsorbent is low and the operation cost is high.

[0017] CN113856637A discloses a method for removing residual metals in the production process of COC and COP by a complexing adsorption filler. Compared with conventional adsorption resins, the adsorption filler has advantages such as a fast metal deashing rate and a large adsorption capacity, and at the same time, there is no swelling phenomenon. The adsorption filler is produced by a method in which silica solid, a solvent, and phosphorus tribromide are reacted in a specified ratio to obtain silica bromide solid, and then further reacted with an appropriate amount of diethyl iminodiacetate to obtain a yellow solid, which is acidified with hydrochloric acid to obtain the adsorption filler. The production process of the adsorption filler is complex and cumbersome, and the removal rate of heavy metals is not high.

[0018] US5073621A discloses a method for demetallization using water as a solubilizer. The method can preferably remove metals in the polymer latex by first dissolving a dicarboxylic acid in water and then adding it to the polymer latex. However, this method is likely to cause emulsification of the latex, is disadvantageous for the reaction between the dicarboxylic acid and metal ions, affects the removal rate of metals, and the process is difficult to control.

[0019] CN1067898A discloses a method for removing residual metal catalysts after hydrogenation of polymers. The method adds hydrogen peroxide water as an oxidizing agent and sebacic acid as a precipitating agent to hydrogenated butadiene-styrene random copolymer latex, dissolves sebacic acid in a diethylene glycol-butyl ether aqueous solution to form a sebacic acid solution, and greatly improves the removal effect of metals in the latex. However, the sites of the two carboxyl groups of the dicarboxylic acid used in this method are not constant, and the complexing effect on metals is poor, so the removal rate of metals is low.

[0020] The conventional demetallization technology in the polymer solution polymerization process has disadvantages such as a complex adsorbent preparation process, a long demetallization process, and a low removal efficiency. Therefore, developing a new continuous solution polymerization method and system has become one of the urgent problems to be solved in this field.

Summary of the Invention

[0021] To solve the above technical problems, an object of the present invention is to provide a continuous solution polymerization method and system. The method and system of the present invention can deeply and efficiently remove the metals remaining in the polymer, and have the advantages such as a short process, low production cost, and continuous operation in a long cycle.

[0022] To achieve the above object, a first aspect of the present invention is Step (1): subjecting the raw materials of the polymerization reaction to a polymerization reaction to obtain a polymer solution, Step (2): mixing the polymer solution with a complexing agent and reacting, then obtaining a mixed solution, washing the mixed solution with water to obtain a polymer solution after demetallization, Step (3): devolatilizing the polymer solution after demetallization to obtain a polymer and volatiles after devolatilization, Step (4): extruding and granulating the polymer after devolatilization to obtain polymer particles, A continuous solution polymerization method comprising The complexing agent includes one or a combination of multiple kinds of dicarboxylic acids and their derivatives. The dicarboxylic acid includes a carbon-carbon double bond, and two carboxyl groups are arranged on the same side of the carbon-carbon double bond, and is in a cis structure in the spatial arrangement, and provides a continuous solution polymerization method.

[0023] In the above continuous solution polymerization method, preferably, in step (1), the raw materials of the polymerization reaction include an olefin monomer, a solvent, and a catalyst system. More preferably, the raw materials of the polymerization reaction further include a scavenger.

[0024] In some specific embodiments of the present invention, the olefin monomer includes one or more combinations of ethylene, α-olefin, cycloolefin, etc. Preferably, the olefin monomer includes ethylene and a comonomer, and the comonomer includes α-olefin and / or cycloolefin, etc. According to specific embodiments of the present invention, the cycloolefin includes one or more combinations of norbornene, cyclopentene, cyclohexene, etc.

[0025] In some specific embodiments of the present invention, the solvent includes one or more combinations of C6-C12 alkanes, cycloalkanes, aromatic hydrocarbons, etc. Preferably, the solvent includes one or more combinations of cyclohexane, methylcyclohexane, n-hexane, toluene, etc.

[0026] In some specific embodiments of the present invention, the catalyst system includes a metallocene catalyst system including a main catalyst that is a metallocene compound and a cocatalyst. Generally, the metallocene compound includes a complex formed by coordination of a Group IVB, VB, VIB transition metal element, particularly vanadium, titanium, zirconium, etc., and a ligand such as cyclopentadiene or a cyclopentadiene derivative. Specifically, it can include various metallocene compounds that are common or disclosed in prior art documents in the field of olefin polymerization. According to specific embodiments of the present invention, the cocatalyst includes one or more combinations of alkylaluminoxane and / or organic boride, etc. Specifically, the alkylaluminoxane includes one or more combinations of methylaluminoxane (MAO), modified methylaluminoxane (MMAO), ethylaluminoxane (EAO), isobutylaluminoxane (i-BAO), etc. The organic boride includes one or more combinations of tris(pentafluorophenyl)boron, N,N-dimethyl-tetrakis(pentafluorophenyl)boron, tris(pentafluorophenyl)carbon-tetrakis(pentafluorophenyl)boron, etc.

[0027] In some specific embodiments of the present invention, the cleaning agent contains alkyl aluminum and / or alkyl aluminum halide, etc. Specifically, it can include trimethyl aluminum, triethyl aluminum, tri-n-propyl aluminum, triisobutyl aluminum, tri-n-butyl aluminum, triisobutyl aluminum, tri-n-pentyl aluminum, tri-n-hexyl aluminum, triisohexyl aluminum, diethyl methyl aluminum, dimethyl ethyl aluminum, monochloro dimethyl aluminum, dichloro monomethyl aluminum, monochloro diethyl aluminum, dichloro monoethyl aluminum, monochloro di-n-propyl aluminum, dichloro mono-n-propyl aluminum, monochloro diisobutyl aluminum, dichloro mono-isobutyl aluminum, monochloro di-n-butyl aluminum, dichloro mono-n-butyl aluminum, monochloro diisopentyl aluminum, dichloro mono-isopentyl aluminum, monochloro di-n-hexyl aluminum, dichloro-n-hexyl aluminum, monochloro isohexyl aluminum, and dichloro mono-isohexyl aluminum, etc., and can include one or a combination of multiple types thereof. Preferably, the cleaning agent contains triisobutyl aluminum and / or triethyl aluminum, etc.

[0028] According to specific embodiments of the present invention, the mixing ratio of the olefin monomer, solvent, catalyst system, and cleaning agent in the raw materials of the polymerization reaction can be usually adjusted by those skilled in the art according to different production needs and different target products, and the present invention does not particularly limit the mixing ratio.

[0029] In the above continuous solution polymerization method, preferably, in step (1), the temperature of the polymerization reaction is 70 to 180 °C, and more preferably 80 to 145 °C.

[0030] In the above continuous solution polymerization method, preferably, in step (1), the pressure of the polymerization reaction is 0.5 to 1.5 MPa, and more preferably 0.6 to 1.2 MPa.

[0031] In the above continuous solution polymerization method, preferably, in step (1), the time of the polymerization reaction is 30 to 120 minutes, more preferably 45 to 100 minutes.

[0032] In some specific embodiments of the present invention, in step (1), the polymerization reaction is carried out in a polymerization reaction tank. The main catalyst, co-catalyst, the scavenger, the olefin monomer, and the solvent in the metallocene catalyst system can be introduced into the polymerization reaction tank from the bottom of the polymerization reaction tank to carry out the polymerization reaction. Specifically, a stirrer, such as a paddle mixer, is installed in the polymerization reaction tank. The polymerization reaction process can adopt a full kettle operation method, and the polymer solution obtained after the reaction flows out from the top of the polymerization reaction tank. Also, a pressure control valve for controlling the pressure of the polymerization reaction may be provided in the polymer solution transfer line of the polymerization reaction tank. At the same time, the polymerization reaction temperature can be controlled by the jacket of the polymerization reaction tank using a high and low temperature oil bath system. Also, a cooling coil is not installed in the polymerization reaction tank to prevent the polymer from adhering to the tube wall of the cooling coil.

[0033] In the above continuous solution polymerization method, preferably, the weight percentage content of the polymer in the polymer solution obtained in step (1) is 15 to 45%, more preferably, the weight percentage content of the polymer in the polymer solution is 25 to 35%.

[0034] In some specific embodiments of the present invention, the metal content in the polymer solution is 300 to 2000 ppm.

[0035] In the above continuous solution polymerization method, preferably, the resulting polymer can include one or a combination of cycloolefin copolymer (COC), cycloolefin polymer (COP), polyethylene, polypropylene, polyolefin plastomer (POP), and polyolefin elastomer (POE), etc.

[0036] According to a specific embodiment of the present invention, preferably, the above continuous solution polymerization method further includes a raw material preparation step of preparing an olefin monomer and a solvent before step (1), and the raw material preparation step includes mixing and preheating the olefin monomer and the solvent. More preferably, the raw material preparation step includes mixing the solvent to dissolve ethylene to obtain a mixture of ethylene and the solvent, mixing the solvent to dissolve the comonomer to obtain a mixture of the comonomer and the solvent, mixing the mixture of ethylene and the solvent with the mixture of the comonomer and the solvent, preheating, and then obtaining a mixture of the olefin monomer and the solvent.

[0037] In some specific embodiments of the present invention, the temperature for dissolving ethylene is 20 to 90 °C, and the pressure is 0.1 to 5.0 MPa. Preferably, the temperature for dissolving ethylene is 25 to 50 °C, and the pressure is 0.8 to 3.0 MPa.

[0038] In some specific embodiments of the present invention, the temperature for mixing the comonomer and the solvent is 25 to 75 °C, and the pressure is 0.05 to 0.2 MPa. Preferably, the temperature for mixing the comonomer and the solvent is 35 to 55 °C, and the pressure is 0.1 to 0.15 MPa.

[0039] In some specific embodiments of the present invention, the temperature of the mixture of the olefin monomer and the solvent obtained after mixing and preheating is 60 to 160 °C, preferably 70 to 150 °C.

[0040] In some specific embodiments of the present invention, the solvent used for mixing with ethylene is the same as the solvent used for mixing with the comonomer.

[0041] In some specific embodiments of the present invention, the raw material preparation step for the olefin monomer and the solvent specifically includes storing ethylene in an ethylene buffer tank, and then injecting the ethylene in the ethylene buffer tank into an ethylene dissolution tank, mixing it with the solvent in the ethylene dissolution tank to dissolve the ethylene and obtain a mixture of ethylene and the solvent; mixing the comonomer and the solvent in a comonomer storage tank to dissolve the comonomer and obtain a mixture of the comonomer and the solvent; and then mixing the mixture of ethylene and the solvent and the mixture of the comonomer and the solvent in a line according to the molar ratio of ethylene to the comonomer (ordinary design by those skilled in the art), and preheating them in a preheater to obtain a mixture of the olefin monomer and the solvent. Here, the ethylene stored in the ethylene buffer tank may include fresh ethylene and / or recycled ethylene. In some specific embodiments of the present invention, the mixture of the olefin monomer and the solvent then enters a polymerization reaction tank, contacts a catalyst system and a scavenger whose addition can be selected, and performs the polymerization reaction described in step (1).

[0042] In the above continuous solution polymerization method, preferably, in step (2), the dicarboxylic acid has a structure represented by the following formula I.

Chemical formula

[0043] In the above continuous solution polymerization method, preferably, in step (2), the derivative of the dicarboxylic acid includes one or a combination of a plurality of acid anhydrides, acid halides, amides, esters, nitriles, etc. formed from the dicarboxylic acid. More preferably, the derivative of the dicarboxylic acid includes an acid anhydride of the dicarboxylic acid.

[0044] According to a specific embodiment of the present invention, the acid anhydride of the dicarboxylic acid has a structure represented by the following formula II.

Chemical formula

[0045] In some specific embodiments of the present invention, in step (2), the dicarboxylic acid and its derivatives include one or more combinations such as cis-butenedioic acid (i.e., maleic acid), cis-butenedioic anhydride (i.e., maleic anhydride), cis-methylbutenedioic acid (i.e., 2-methylmaleic acid), cis-methylbutenedioic anhydride (i.e., 2-methylmaleic anhydride), 2,3-dimethylmaleic acid, and 2,3-dimethylmaleic anhydride.

[0046] In the continuous solution polymerization method of the present invention, in the step of demetallizing the polymer solution, a dicarboxylic acid and its derivatives having a cis structure in the configuration are employed as a metal complexing agent. Such dicarboxylic acids and their derivatives react with metal ions in the polymer solution to form stable water-soluble metal complexes. Then, the removal of the water-soluble metal complexes is completed by washing with water, and the obtained oil phase is the polymer solution after demetallization.

[0047] In some specific embodiments of the present invention, the structural formula of the metal complex formed by the dicarboxylic acid and its derivatives and metal ions is represented by the following formula III.

Chemical formula

[0048] In the above continuous solution polymerization method, preferably, in step (2), the mixing ratio of the polymer solution and the complexing agent is 1 g of polymer: 10 -3 ~10 -5 mol of complexing agent (that is, one or a combination of more than one of dicarboxylic acid and its derivatives).

[0049] In the above continuous solution polymerization method, preferably, in step (2), the complexing agent is mixed with the polymer solution as a solution, and the concentration of the complexing agent solution is 0.1 to 10 mol / L, more preferably 0.1 to 5 mol / L. In some specific embodiments of the present invention, the solvent in the complexing agent solution may include one or a combination of more than one of water, alcohols, ketones, and hydrocarbons, preferably including one or a combination of more than one of water, ethanol, and acetone.

[0050] In the above continuous solution polymerization method, preferably, in step (2), the process of mixing and reacting the polymer solution and the complexing agent is carried out under stirring, and the rotation speed of the stirring can be adjusted by those skilled in the art according to the production scale, and preferably, it is stirred vigorously.

[0051] In the above continuous solution polymerization method, preferably, in step (2), the temperature for mixing and reacting the polymer solution and the complexing agent is 60 to 150°C, more preferably 80 to 130°C.

[0052] In the above continuous solution polymerization method, preferably, in step (2), the reaction time between the polymer solution and the complexing agent is 2 to 120 minutes, more preferably 5 to 60 minutes.

[0053] According to a specific embodiment of the present invention, after the polymerization reaction, the solvent in the complexing agent solution can be used as a terminator to deactivate the active centers in the polymer solution, efficiently terminate the progress of the polymerization reaction, and prevent the problem of continued polymerization or explosion problems in the subsequent treatment process. Therefore, the complexing agent solution used in the present invention, as a metal complexing agent and also as a terminator, synergistically and continuously proceeds the process of stopping the polymerization reaction and the process of complexing the metal, improving the process efficiency.

[0054] In some specific embodiments of the present invention, step (2) specifically includes putting the polymer solution (from the polymerization reaction tank) into a heat exchanger, depressurizing it, and then putting it into an end-complexing device, injecting a complexing agent (specifically, it may also be the above complexing agent solution) into the end-complexing device, stopping the polymerization reaction, and at the same time forming metal ions in the polymer solution into water-soluble metal complexes to obtain a mixed solution, separating the oil and water of the mixed solution, heat-exchanging the obtained oil phase, washing it with water, and performing oil-water separation after washing with water, where the obtained oil phase can be the polymer solution after demetallization.

[0055] In some specific embodiments of the present invention, the end-complexing equipment may be a conventional tank-type equipment with a stirrer, and the present invention does not particularly limit its structure.

[0056] In some specific embodiments of the present invention, the temperature of the polymer solution after heat exchange is 60 to 150 °C, preferably 80 to 130 °C. In order to prevent the polymer solution from vaporizing after being depressurized, a treatment method of cooling the polymer solution flowing out of the polymerization reaction tank and then depressurizing it is adopted. The polymer solution can be heat-exchanged and cooled using a heat exchanger.

[0057] In some specific embodiments of the present invention, the pressure after decompression of the polymer solution is 0.03 to 0.1 MPa, preferably 0.03 to 0.08 MPa. The polymer solution may be decompressed with a pressure control valve.

[0058] In some specific embodiments of the present invention, the number of times of the water washing is 1 to 5 times.

[0059] In some specific embodiments of the present invention, the temperature of the water washing is 30 to 60 °C, and the volume ratio of the amount of water used for the water washing to the volume of the oil phase is 1 to 20:1. This amount of water used is the amount of water used for each water washing.

[0060] Those skilled in the art can understand that when performing multiple water washings, oil-water separation is performed after each water washing to obtain an oil phase. The water-soluble metal complex is in the aqueous phase and is removed after the oil-water separation.

[0061] In some specific embodiments of the present invention, the oil-water separation can be performed using an ordinary centrifuge.

[0062] In the above continuous solution polymerization method, preferably, the metal content in the polymer solution after demetallization obtained in step (2) is less than 1 ppm.

[0063] In the above continuous solution polymerization method, preferably, in step (3), the polymer solution after demetallization is devolatilized at a pressure of 10 to 50 bar and a temperature of 210 to 280 °C. Here, the devolatilization may be flash devolatilization.

[0064] In some specific embodiments of the present invention, the equipment used for devolatilizing the polymer solution after demetallization may include a flash tank.

[0065] In some specific embodiments of the present invention, step (3) specifically includes subjecting the polymer solution after demetallization to heat exchange, then placing it in a flash tank, and flash-separating the polymer solution after demetallization to obtain a polymer after devolatilization and volatiles. The polymer after devolatilization flows out from the bottom of the flash tank, and the volatiles flow out from the top of the flash tank.

[0066] In some specific embodiments of the present invention, the temperature of the polymer solution after demetallization is 210 - 360°C, preferably 220 - 300°C, after heat exchange. Heat exchange and temperature increase can be performed on the polymer solution after demetallization by a heat exchanger.

[0067] In the above continuous solution polymerization method, preferably, the volatile content in the polymer after devolatilization obtained in step (3) is 5% or less (weight percentage content).

[0068] In some specific embodiments of the present invention, by using two or more flash tanks connected in series to devolatilize the polymer solution after demetallization, the volatiles remaining in the polymer solution can be removed as much as possible, and the volatile content in the polymer after devolatilization can be made 5% or less. Each flash tank may be provided with one heat exchanger for providing the heat required for the devolatilization step. At the same time, in order to send the polymer after devolatilization to downstream equipment, a gear pump or a screw pump applicable to high-viscosity fluid transportation may be installed at the bottom of each flash tank.

[0069] In some specific embodiments of the present invention, the volatiles obtained after the polymer solution after demetallization is devolatilized include one or a combination of ethylene, unreacted comonomer, solvent, and the like. Preferably, the weight percentage content of the unreacted comonomer in the volatiles obtained in step (3) is 20% - 55%, more preferably 30% - 45%.

[0070] In the above continuous solution polymerization method, preferably, in step (4), the equipment for extruding and pelletizing the polymer after devolatilization includes an extrusion granulator, and a degassing port is installed at the extrusion end of the extrusion granulator. After extrusion, the volatile components in the polymer after devolatilization are further removed, and then pelletized at the pelletizing end of the extrusion granulator to obtain polymer particles. More preferably, a vacuum degassing device is installed at the extrusion end of the extrusion granulator, and the vacuum degassing device is connected to the degassing port. The vacuum degassing device includes, but is not limited to, a vacuum pump.

[0071] In some specific embodiments of the present invention, the polymer after devolatilization enters the extrusion granulator through a gear pump or a screw pump installed at the bottom of the flash tank.

[0072] In some specific embodiments of the present invention, the extrusion granulator includes a twin-screw extrusion granulator. Preferably, the aspect ratio of the extrusion screw of the twin-screw extrusion granulator is 40-80:1, and more preferably 45-65:1.

[0073] In some specific embodiments of the present invention, the number and position of the degassing ports at the extrusion end of the extrusion granulator can be adjusted by those skilled in the art according to the actual situation. Preferably, a degassing port and a vacuum degassing device connected to the degassing port are respectively provided in the middle and at the end of the extrusion end of the extrusion granulator. According to the specific embodiments of the present invention, if the number of degassing ports of the extrusion granulator is too small, the volatile components separated from the polymer latex cannot be removed from the extrusion granulator in a timely manner, and the volatile components will dissolve in the polymer latex again, affecting the devolatilization efficiency. If the number of degassing ports is too large, although the volatile components can be removed in a timely manner, the heat exchange area of the cylinder of the extrusion granulator will be significantly reduced, the heat exchange capacity of the cylinder will be decreased, and the devolatilization ability of the extrusion granulator will be decreased.

[0074] In some specific embodiments of the present invention, a stripping port may be further provided at the extrusion end of the extrusion granulator, and steam is continuously injected through the stripping port to form an azeotrope with the steam and the volatile components, which is advantageous for reducing the partial pressure of the gas phase, increasing the interfacial area, and replacing the volatile components from the polymer latex.

[0075] In the above continuous solution polymerization method, preferably, the polymer particles obtained in step (4) have a VOC content of less than 50 ppm.

[0076] According to a specific embodiment of the present invention, preferably, the above continuous solution polymerization method further includes a step (5) of rectifying the volatile components obtained in step (3). More preferably, step (5) further includes rectifying the volatile components removed by extrusion granulation in step (4). In some specific embodiments of the present invention, after rectification, ethylene, unreacted comonomer, and solvent can be obtained respectively.

[0077] In some specific embodiments of the present invention, the rectification can be carried out using a rectification column. Preferably, the operating conditions of the rectification column are that the bottom temperature of the column is 130 - 150 °C, the bottom pressure of the column is 10 - 30 Torr, the maximum temperature at the top of the column is 90 - 110 °C, and the reflux ratio is 1 - 25, preferably 5 - 20.

[0078] Specifically, step (5) includes putting the volatile components obtained in step (3) and the volatile components removed by extrusion granulation in step (4) into a rectification column for rectification. The ethylene flowing out from the top of the rectification column enters a reflux tank, and after exhaust and gas-liquid separation, ethylene is obtained. At the same time, the unreacted comonomer flowing out from the side wall of the rectification column and the solvent flowing out from the bottom of the rectification column are obtained. After gas-liquid separation in the reflux tank, the liquid phase obtained can be returned to the rectification column to perform rectification again.

[0079] According to a specific embodiment of the present invention, preferably, the above continuous solution polymerization method further includes a step (6) of recycling one or more of ethylene, unreacted comonomer, and solvent obtained in step (5). Specifically, step (6) can include compressing the ethylene gas-liquid separated in the reflux tank and then returning it to step (1) as one of the raw materials for the polymerization reaction, and / or returning the rectified unreacted comonomer and / or solvent to step (1) as one of the raw materials for the polymerization reaction.

[0080] In some specific embodiments of the present invention, the ethylene obtained after gas-liquid separation in the reflux tank is compressed by a compressor and then returned to the ethylene buffer tank and recycled as one of the raw materials for the polymerization reaction. In the present invention, the recycled ethylene is referred to as circulating ethylene.

[0081] In some specific embodiments of the present invention, the unreacted comonomer flowing out from the side wall of the rectification column is returned to the comonomer storage tank, and the solvent flowing out from the bottom of the rectification column is returned to the ethylene dissolution tank and / or the comonomer storage tank and can be recycled as one of the raw materials for the polymerization reaction.

[0082] A second aspect of the present invention provides a continuous solution polymerization system for realizing the above continuous solution polymerization method, and the system includes at least a polymerization reaction unit, a metal removal unit, a devolatilization unit, and an extrusion granulation unit.

[0083] Here, the polymerization reaction unit includes at least a polymerization reaction tank, and at least a polymerization reaction raw material inlet and a polymer solution outlet are provided in the polymerization reaction tank.

[0084] The metal removal unit includes at least an end complexing facility and a water washing tank. At least a polymer solution inlet, a complexing agent inlet, and a mixed solution outlet are provided in the end complexing facility, and an oil phase inlet, a water inlet, and a polymer solution outlet are provided in the water washing tank.

[0085] The devolatilization unit includes at least a flash tank, and the flash tank is provided with at least a material inlet, a polymer outlet after devolatilization, and a volatile matter outlet.

[0086] The extrusion granulation unit includes at least an extrusion granulator.

[0087] The polymer solution outlet of the polymerization reaction tank is connected to the polymer solution inlet of the termination and complexation equipment via a line, the mixed liquid outlet of the termination and complexation equipment is connected to the oil phase inlet of the water washing tank via a line, the polymer solution outlet of the water washing tank is connected to the material inlet of the flash tank via a line, and the polymer outlet after devolatilization of the flash tank is connected to the extrusion granulator via a line.

[0088] In the above continuous solution polymerization system, preferably, the polymerization reaction raw material inlet of the polymerization reaction tank is installed at the bottom of the polymerization reaction tank, and the polymer solution outlet is installed at the top of the polymerization reaction tank. In some specific embodiments of the present invention, the polymerization reaction raw material inlet of the polymerization reaction tank includes an olefin monomer and solvent inlet, and a catalyst system and an optionally installed scavenger inlet. Specifically, the main catalyst, co-catalyst, and the scavenger in the metallocene catalyst system are respectively conveyed by material conveying branch lines, and the three material conveying branch lines are connected to the catalyst system and scavenger inlet of the polymerization reaction tank after merging into the main material conveying pipe. Preferably, the three material conveying branch lines are connected to the catalyst system and scavenger inlet of the polymerization reaction tank via a loop tube reactor after merging into the main raw material conveying pipe, and the loop tube reactor is used to enhance the mixing and activation of the main catalyst, co-catalyst, and the scavenger in the metallocene catalyst system.

[0089] In the above continuous solution polymerization system, preferably, the polymerization reaction tank is provided with a stirrer, such as a paddle mixer.

[0090] In the above continuous solution polymerization system, preferably, an external jacket is installed in the polymerization reaction tank, and the polymerization reaction temperature can be controlled by the external jacket of the polymerization reaction tank using a high and low temperature oil bath system.

[0091] In the above continuous solution polymerization system, preferably, a cooling coil is not installed in the polymerization reaction tank to prevent the polymer from adhering to the tube wall of the cooling coil.

[0092] In the above continuous solution polymerization system, preferably, a heat exchanger and a pressure control valve are installed in the line connecting the polymer solution outlet of the polymerization reaction tank and the polymer solution inlet of the termination and complexation equipment.

[0093] According to a specific embodiment of the present invention, preferably, the above continuous solution polymerization system includes a raw material preparation unit including at least an ethylene buffer tank, an ethylene dissolution tank, and a comonomer storage tank. In the ethylene buffer tank, a fresh ethylene inlet, a circulating ethylene inlet that can be selected whether to install or not, and an ethylene outlet may be installed. In the ethylene dissolution tank, a solvent inlet, an ethylene inlet, and a mixture outlet of ethylene and solvent may be installed. In the comonomer storage tank, a solvent inlet, a comonomer inlet, and a mixture outlet of comonomer and solvent may be installed. The ethylene outlet of the ethylene buffer tank is connected to the ethylene inlet of the ethylene dissolution tank via a line. Material transfer branch lines are respectively installed at the mixture outlet of ethylene and solvent of the ethylene dissolution tank and the mixture outlet of comonomer and solvent of the comonomer storage tank. The two material transfer branch lines merge into a main material transfer pipe and then are connected to the olefin monomer and solvent inlet of the polymerization reaction tank. More preferably, a preheater is installed in the main material transfer pipe.

[0094] In some specific embodiments of the present invention, the termination and complexation equipment may be a tank-type equipment with a normal stirrer, and the present invention does not particularly limit its structure.

[0095] In the above continuous solution polymerization system, preferably, the polymer solution inlet of the termination and complexation facility is installed at the bottom of the termination and complexation facility, the complexing agent inlet is installed at the bottom of the termination and complexation facility, and the mixed liquid outlet is installed at the top of the termination and complexation facility.

[0096] In the above continuous solution polymerization system, preferably, the demetallization unit further includes a complexing agent storage tank, and the complexing agent storage tank is connected to the complexing agent inlet of the termination and complexation facility via a line.

[0097] In the above continuous solution polymerization system, preferably, a centrifuge is provided on the line connecting the mixed liquid outlet of the termination and complexation facility and the oil phase inlet of the water washing tank. More preferably, a heat exchanger for bringing the oil phase to the operating temperature of the water washing is installed on the line connecting the centrifuge and the oil phase inlet of the water washing tank.

[0098] In the above continuous solution polymerization system, preferably, a centrifuge is provided on the line connecting the polymer solution outlet of the water washing tank and the material inlet of the flash tank.

[0099] In the above continuous solution polymerization system, preferably, the number of the water washing tanks is 1 to 5. When a plurality of water washing tanks are employed, the plurality of water washing tanks are installed in series. A centrifuge is installed on each line connected to the polymer solution outlet of each water washing tank to separate the oil and water in the solution after water washing to obtain an oil phase. And after each centrifuge, a heat exchanger for bringing the oil phase to the operating temperature of the water washing is installed.

[0100] In the above continuous solution polymerization system, preferably, the material inlet of the flash tank is provided on the side wall of the flash tank, the polymer outlet after devolatilization is provided at the bottom of the flash tank, and the volatiles outlet is provided at the top of the flash tank.

[0101] In the above continuous solution polymerization system, preferably, the number of the flash tanks is one or two or more. When two or more flash tanks are adopted, the two or more flash tanks are provided in series. More preferably, so as to provide the heat quantity required for the devolatilization process, each flash tank is provided with one heat exchanger, the heat exchanger is installed in a line connected to the material inlet of the flash tank, and a conveying pump is installed in each line connected to the polymer outlet after devolatilization of the flash tank so as to transport the polymer after devolatilization. Specifically, the conveying pump can include, but is not limited to, a gear pump or a screw pump, etc.

[0102] In the above continuous solution polymerization system, preferably, a degassing port is provided at the extrusion end of the extrusion granulator. More preferably, the number of the degassing openings is two, and they are respectively installed at the middle stage and the end of the extrusion end of the extrusion granulator. Even more preferably, a vacuum degassing device is installed at the extrusion end of the extrusion granulator, and the vacuum degassing device is connected to the degassing port. The vacuum degassing device includes, but is not limited to, a vacuum pump.

[0103] In the above continuous solution polymerization system, preferably, the extrusion granulator includes a twin-screw extrusion granulator. More preferably, the aspect ratio of the extrusion screw of the twin-screw extrusion granulator is 40 to 80:1, and even more preferably 45 to 65:1.

[0104] In the above continuous solution polymerization system, preferably, a stripping port is further provided at the extrusion end of the extrusion granulator. By continuously injecting steam through the stripping port, it is advantageous to form an azeotrope with the steam and the volatile components, reduce the partial pressure of the gas phase, increase the interfacial area, and replace the volatile components from the polymer latex.

[0105] According to a specific embodiment of the present invention, preferably, the continuous solution polymerization system further includes a rectification unit including at least a rectification column and a reflux tank. The rectification column is provided with a volatile component inlet, an ethylene outlet, an unreacted comonomer outlet, and a solvent outlet. The volatile component inlet of the rectification column is connected to the volatile component outlet of the flash tank via a line. The ethylene outlet of the rectification column communicates with the reflux tank. A reflux line is installed in the reflux tank. The reflux line is connected to the rectification column, and the liquid phase separated by gas-liquid separation in the reflux tank is returned to the rectification column for rectification again. Specifically, the volatile component inlet of the rectification column is installed on the side wall of the rectification column, the ethylene outlet is installed at the top of the rectification column, the unreacted comonomer outlet is installed on the side wall of the rectification column, and the solvent outlet may be installed at the bottom of the rectification column.

[0106] In the above continuous solution polymerization system, preferably, the degassing port at the extrusion end of the extrusion granulator communicates with the volatile component inlet of the rectification column via a line. Specifically, the degassing port at the extrusion end of the extrusion granulator communicates with the volatile component inlet of the rectification column via a line and the vacuum degassing device.

[0107] According to a specific embodiment of the present invention, preferably, the continuous solution polymerization system further includes a circulation unit including at least a compressor. The inlet of the compressor is connected to the reflux tank via a line, and the outlet of the compressor is connected to the circulating ethylene inlet of the ethylene buffer tank via a line.

[0108] In the above continuous solution polymerization system, preferably, the circulation unit further includes a comonomer circulation line that communicates the unreacted comonomer outlet of the rectification column with the comonomer inlet of the comonomer storage tank.

[0109] In the above continuous solution polymerization system, preferably, the circulation unit further includes a solvent circulation line that communicates the solvent outlet of the rectification column with the solvent inlet of the ethylene dissolution tank and / or the solvent inlet of the comonomer storage tank.

[0110] In the field, in the process of producing polyolefin using a metallocene catalyst system and a solution polymerization method, usually, the residual content of the catalyst metal in the polymer solution obtained after the polymerization reaction is high. If the removal of the residual metal is insufficient, it will discolor the polyolefin product and deteriorate the performance such as heat resistance and durability of the polyolefin product.

[0111] In demetallization, the technical solution of the present invention adopts a dicarboxylic acid having a cis structure in the spatial arrangement and its derivatives as a metal complexing agent. Such a dicarboxylic acid having a cis structure and its derivatives form a cyclic transition state with metal ions in the polymer solution, and further form a water-soluble metal complex having a more stable cyclic structure. Then, the removal of the water-soluble metal complex is completed by washing with water to obtain a polymer solution after demetallization. Therefore, the technical solution of the present invention can efficiently remove the metal ions remaining in the polymer solution and significantly reduce the residual metal in the polymer product, especially the polyolefin product. Compared with the conventional polymer demetallization technology, the technical solution of the present invention has the advantages of high demetallization efficiency, fast speed, simple process, low cost, and can be continuously operated in a long cycle. It can be widely applied in the field of polymer metal removal, has versatility and efficiency, and has broad industrialization prospects.

[0112] The continuous solution polymerization method and system of the present invention have at least the following beneficial technical effects.

[0113] 1. The present invention uses a dicarboxylic acid having a cis structure in the spatial arrangement and its derivatives as a metal complexing agent, forms a cyclic transition state with metal ions, promotes the formation of metal complexes, and forms a stable water-soluble metal complex, thereby having the advantage of efficiently complexing and removing metals, and significantly improving the metal removal rate of the polymer solution.

[0114] 2. Since the present invention removes the metal complex by washing with water, it has the advantages of simple operation and low cost.

[0115] 3. The complexing agent solution used in the present invention can be simultaneously used as a polymerization reaction terminator, and the process of terminating the polymerization reaction and the process of complexing the metal can proceed synergistically and continuously, which is advantageous for adjusting the polymer molecular weight and molecular weight distribution and improving the process efficiency.

[0116] As described above, the present invention provides a continuous solution polymerization method and system, and in particular, provides a method and system for producing polyolefin by continuous solution polymerization using a metallocene catalyst. The method and system of the present invention can deeply and efficiently remove the metal remaining from the catalyst in the polymer, and can produce polymer products with high transparency, low metal content, and low VOC content. At the same time, the produced polymer products have advantages such as heat resistance, aging resistance, and high dielectric properties. The polymer products produced by the method and system of the present invention can meet the requirements of medical grade and optical grade polymer materials. In addition, the method and system of the present invention have advantages such as a short process, low production cost, and the ability to operate continuously in a long cycle.

Brief Description of the Drawings

[0117]

Figure 1

Description of the Reference Numerals

[0118] 1: Ethylene buffer tank 2: Ethylene dissolution tank 3: Comonomer storage tank 4: Polymerization reactor 5: Termination / complexation equipment 6: Complexing agent storage tank 7: Water washing tank 8: First centrifuge 9: Second centrifuge 10: Flash tank 11: Gear pump 12: Rectification tower 13: Extrusion granulator 14: Reflux tank 15: Compressor 16: Preheater 17: First heat exchanger 18: Second heat exchanger 19: Third heat exchanger 20: Pressure control valve 21: Loop tube reactor, 131: Degassing port 132: Vacuum degassing device.

Embodiments for Carrying Out the Invention

[0119] To more clearly understand the technical features, objectives, and beneficial effects of the present invention, the technical solution of the present invention will be described in detail below, but it should not be understood as limiting the scope of implementation of the present invention.

[0120] Example 1 As shown in FIG. 1, this example provides a continuous solution polymerization system including a raw material preparation unit, a polymerization reaction unit, a demetallization unit, a devolatilization unit, an extrusion granulation unit, a rectification unit, and a circulation unit.

[0121] Here, the raw material preparation unit includes at least an ethylene buffer tank 1, an ethylene dissolution tank 2, and a comonomer storage tank 3. The ethylene buffer tank 1 is provided with a fresh ethylene inlet, a circulating ethylene inlet, and an ethylene outlet. The ethylene dissolution tank 2 is provided with a solvent inlet, an ethylene inlet, and an ethylene and solvent mixture outlet. The comonomer storage tank 3 is provided with a solvent inlet, a comonomer inlet, and a comonomer and solvent mixture outlet.

[0122] The polymerization reaction unit includes at least a polymerization reaction tank 4. The polymerization reaction tank 4 is provided with an olefin monomer and solvent inlet, a catalyst system and scavenger inlet, and a polymer solution outlet.

[0123] The demetallization unit includes at least a termination and complexation facility 5, a complexing agent storage tank 6, a water washing tank 7, a first centrifuge 8, and a second centrifuge 9. The termination and complexation facility 5 is provided with a polymer solution inlet, a complexing agent inlet, and a mixture outlet. The water washing tank 7 is provided with an oil phase inlet, a deionized water inlet, and a polymer solution outlet.

[0124] The devolatilization unit includes at least a flash tank 10. The flash tank 10 is provided with a material inlet, a devolatilized polymer outlet, and a volatile matter outlet.

[0125] The extrusion granulation unit includes at least an extrusion granulator 13.

[0126] The rectification unit includes at least a rectification column 12 and a reflux tank 14. The rectification column 12 is provided with a volatile matter inlet, an ethylene outlet, an unreacted comonomer outlet, and a solvent outlet.

[0127] The circulation unit includes at least a compressor 15, a comonomer circulation line (not shown in FIG. 1), and a solvent circulation line (not shown in FIG. 1).

[0128] The ethylene outlet of the ethylene buffer tank 1 is connected to the ethylene inlet of the ethylene dissolution tank 2 via a line. Material transfer branch lines are respectively installed at the outlet of the mixture of ethylene and solvent in the ethylene dissolution tank 2 and the outlet of the mixture of comonomer and solvent in the comonomer storage tank 3. The two material transfer branch lines merge into the main material transfer pipe and then are connected to the olefin monomer and solvent inlet of the polymerization reactor 4. In addition, metering pumps (not shown in FIG. 1) are respectively provided on the two material transfer branch lines, and a preheater 16 is provided on the main material transfer pipe.

[0129] The main catalyst, cocatalyst, and scavenger in the metallocene catalyst system are respectively transported by the material transfer branch lines. The three material transfer branch lines merge into the main material transfer pipe and then are connected to the catalyst system and scavenger inlet of the polymerization reactor 4 via the loop pipe reactor 21. In addition, syringe pumps (not shown in FIG. 1) are respectively provided on the three material transfer branch lines. The loop pipe reactor 21 is used to enhance the mixing and activation of the main catalyst, cocatalyst, and scavenger in the metallocene catalyst system.

[0130] The polymer solution outlet of the polymerization reactor 4 is connected to the polymer solution inlet of the termination and complexation facility 5 via a line, and a first heat exchanger 17 and a pressure control valve 20 are installed on the line.

[0131] A stirrer, such as a paddle mixer, is installed in the polymerization reaction tank 4. An external jacket is installed in the polymerization reaction tank 4, and the polymerization reaction temperature can be controlled by the external jacket of the polymerization reaction tank 4 using a high and low temperature oil bath system. A cooling coil is not provided in the polymerization reaction tank 4 to prevent the polymer from adhering to the tube wall of the cooling coil.

[0132] The complexing agent storage tank 6 is connected to the complexing agent inlet of the termination and complexing equipment 5 via a line.

[0133] The mixed liquid outlet of the termination and complexing equipment 5 is connected to the oil phase inlet of the water washing tank 7 via a line, and a first centrifuge 8 and a second heat exchanger 18 are installed in this line.

[0134] The termination and complexing equipment 5 may be a normal tank-type equipment with a stirrer.

[0135] The polymer solution outlet of the water washing tank 7 is connected to the material inlet of the flash tank 10 via a line, and a second centrifuge 9 and a third heat exchanger 19 are installed in this line.

[0136] In this embodiment, the number of the water washing tanks 7 is 1 to 5 (a plurality of water washing tanks are not shown in FIG. 1). When a plurality of water washing tanks are employed, the plurality of water washing tanks are installed in series. A centrifuge is installed in each line connected to the polymer solution outlet of each water washing tank to separate the oil and water of the solution after water washing to obtain an oil phase. And after each centrifuge, a heat exchanger for bringing the oil phase to the operation temperature of water washing is installed.

[0137] The polymer outlet after devolatilization of the flash tank 10 is connected to the extrusion granulator 13 via a line and a gear pump 11.

[0138] At the extrusion end of the extrusion granulator 13, a degassing port 131 is provided. The number of the degassing ports 131 is two, and they are respectively provided at the middle and the end of the extrusion end of the extrusion granulator 13. A vacuum degassing device 132 is further installed at the extrusion end of the extrusion granulator 13, and the vacuum degassing device 132 is connected to the degassing port 131. The vacuum degassing device 132 includes, but is not limited to, a vacuum pump.

[0139] In this embodiment, the extrusion granulator 13 is a twin-screw extrusion granulator. The aspect ratio of the extrusion screw of the twin-screw extrusion granulator is 45 to 65:1.

[0140] The volatile matter outlet of the flash tank 10 is connected to the volatile matter inlet of the rectification column 12 via a line.

[0141] The degassing port 131 at the extrusion end of the extrusion granulator 13 communicates with the volatile matter inlet of the rectification column 12 via a line and the vacuum degassing device 132.

[0142] The ethylene outlet of the rectification column 12 communicates with the reflux tank 14. A reflux line is provided in the reflux tank 14, which is connected to the rectification column 12 and returns the liquid phase separated by gas-liquid separation in the reflux tank 14 to the rectification column 12 for rectification.

[0143] The inlet of the compressor 15 is connected to the reflux tank 14 via a line, and the outlet of the compressor 15 is connected to the circulating ethylene inlet of the ethylene buffer tank 1 via a line.

[0144] The comonomer circulation line is for communicating the unreacted comonomer outlet of the rectification column 12 and the comonomer inlet of the comonomer storage tank 3.

[0145] The solvent circulation line is for communicating the solvent outlet of the rectification column 12, the solvent inlet of the ethylene dissolution tank 2, and the solvent inlet of the comonomer tank 3.

[0146] Examples 2 to 7 Examples 2 to 7 each provide a continuous solution polymerization method, and all adopted the continuous solution polymerization system provided in Example 1.

[0147] The continuous solution polymerization methods according to Examples 2 to 7 include the following steps.

[0148] Step (1): In the raw material preparation unit, ethylene (including fresh ethylene and recycled ethylene) is stored in ethylene buffer tank 1, and then the ethylene in ethylene buffer tank 1 is gently injected into ethylene dissolution tank 2, where it is mixed with the solvent to fully dissolve the ethylene. The temperature, pressure, and solvent used for dissolving ethylene are shown in Table 1. Calculate the solubility of ethylene under the said dissolution temperature and pressure conditions to obtain a mixture of ethylene and the solvent. The comonomer and the solvent are mixed in comonomer storage tank 3 to dissolve the comonomer. The solvent used for mixing with the comonomer is the same as that used for mixing with ethylene. The temperature and pressure of comonomer storage tank 3 are as shown in Table 1 to obtain a mixture of the comonomer and the solvent. Then, according to the molar ratio of ethylene to the comonomer, after accurately metering by a metering pump, the mixture of ethylene and the solvent and the mixture of the comonomer and the solvent are mixed in the line and preheated by preheater 16 to obtain a mixture of olefin monomer and the solvent, and its temperature is as shown in Table 1.

[0149] Here, the comonomer is a cycloolefin, and the molar ratio of ethylene to the comonomer, the total amount of solvent used, etc. may be normally adjusted by those skilled in the art.

[0150] Step (2): In the polymerization reaction unit, the mixture of the olefin monomer and the solvent obtained in Step (1) is introduced into the polymerization reaction tank 4 from the bottom of the polymerization reaction tank 4. At the same time, the main catalyst, co-catalyst, and scavenger in the metallocene catalyst system are respectively transported by syringe pumps and material transfer branch lines, and they are merged and subjected to enhanced mixing and activation by the loop reactor 21, and then introduced into the polymerization reaction tank 4 from the bottom of the polymerization reaction tank 4. A polymerization reaction is carried out in the polymerization reaction tank 4. The temperature, pressure, and time of the polymerization reaction (i.e., the residence time in the polymerization reaction tank 4) are as shown in Table 1 to obtain a polymer solution. The weight percentage content of the polymer in the polymer solution is as shown in Table 1. The polymerization reaction process adopts a full-creel operation. The polymer solution obtained after the reaction flows out from the top of the polymerization reaction tank 4, and the pressure of the polymerization reaction can be controlled by the pressure control valve 20. At the same time, the temperature of the polymerization reaction can be controlled by the jacket of the polymerization reaction 4 using a high and low temperature oil bath system.

[0151] Here, the main catalyst is a zirconium-containing metallocene compound, the co-catalyst is an alkylaluminoxane, and the scavenger is triisobutylaluminum and / or triethylaluminum, and their usage amounts may all be normally adjusted by those skilled in the art.

[0152] Step (3): In the demetallization unit, after the polymer solution obtained in step (2) is cooled by the first heat exchanger 17, the pressure is reduced by the pressure control valve 20, and then it enters the termination and complexation equipment 5. After the polymer solution is cooled and the pressure is reduced, as shown in Table 1, the complexing agent solution in the complexing agent storage tank 6 is injected into the termination and complexation equipment 5 according to the calculated amount. At the same time as the polymerization reaction is terminated, the metal ions in the polymer solution are formed into water-soluble metal complexes to obtain a mixed solution. The mixed solution is subjected to oil-water separation by the first centrifuge 8, the obtained oil phase is heat-exchanged by the second heat exchanger 18, then put into the water washing tank 7 for water washing, and the water-washed polymer solution is subjected to oil-water separation by the second centrifuge 9. The obtained oil phase is the polymer solution after demetallization. Here, the number of water washing tanks 7 is one or more, and the number of water washing times is 1 to 5 times. The specific number of water washing times, water washing temperature, and water-oil volume are as shown in Table 1.

[0153] Step (4): In the devolatilization unit, after the polymer solution after demetallization obtained in step (3) is heat-exchanged by the third heat exchanger 19, it is put into the flash tank 10, and the polymer solution after demetallization is flash-separated. The temperature, flash temperature, and pressure of the polymer solution after heat exchange are as shown in Table 1 to obtain the polymer after devolatilization and the volatile components. The polymer after devolatilization flows out from the bottom of the flash tank 10, and the volatile components flow out from the top of the flash tank 10. The volatile content in the polymer after devolatilization is 5% or less (weight percentage content), and the weight percentage content of the unreacted comonomer in the volatile components is as shown in Table 1.

[0154] Step (5): In the extrusion granulation unit, the devolatilized polymer obtained in step (4) is injected into the extrusion granulator 13 through the gear pump 11 at the bottom of the flash tank 10. After being extruded from the extrusion end of the extrusion granulator 13, the volatile components remaining in the devolatilized polymer are further removed, and then granulated at the granulation end of the extrusion granulator 13 to obtain polymer particles. The polymer particles have a VOC content of less than 50 ppm. The extrusion granulator 13 is a twin-screw extrusion granulator, and the aspect ratios of the extrusion screws of the twin-screw extrusion granulators used in Examples 2 to 7 are as shown in Table 1.

[0155] Step (6): In the rectification unit, the volatile components flowing out from the top of the flash tank 10 obtained in step (4) and the volatile components removed by the extrusion granulator 13 in step (5) are put into the rectification column 12 for rectification. The operating conditions of the rectification column 12 are as shown in Table 1. The ethylene flowing out from the top of the rectification column 12 enters the reflux tank 14. After performing exhaust and gas-liquid separation, ethylene is obtained. At the same time, the unreacted comonomer flowing out from the side wall of the rectification column 12 and the solvent flowing out from the bottom of the rectification column 12 are obtained. After performing gas-liquid separation in the reflux tank, the liquid phase obtained is returned to the rectification column to perform rectification again.

[0156] Step (7): In the circulation unit, the ethylene gas-liquid separated in the reflux tank 14 is compressed by the compressor 15 and then returned to the ethylene buffer tank 1 and recycled as one of the raw materials for the polymerization reaction. The unreacted comonomer flowing out from the side wall of the rectification column 12 is returned to the comonomer tank 3, and the solvent flowing out from the bottom of the rectification column 12 is returned to the ethylene dissolution tank 2 and the comonomer tank 3 and recycled as one of the raw materials for the polymerization reaction.

[0157]

Table 1-1

Table 1-2

[0158] Example 2 In the demetallization unit, after the polymer solution obtained in step (2) is cooled by the first heat exchanger 17, the pressure is reduced by the pressure control valve 20, and then it enters the termination and complexation equipment 5. Under intense stirring conditions, an aqueous maleic acid solution with a concentration of 0.1 mol / L in the complexing agent storage tank 6 is continuously injected into the termination and complexation equipment 5. The injection amount is 2.5% of the volume of the polymer solution in the termination and complexation equipment 5, and the residence time is 5 minutes. At the same time as the polymerization reaction is terminated, metal ions in the polymer solution are formed into water-soluble metal complexes to obtain a mixed solution. The mixed solution is subjected to oil-water separation by the first centrifuge 8. The obtained oil phase is heat-exchanged by the second heat exchanger 18, then put into the water washing tank 7 for washing. The polymer solution after washing is subjected to oil-water separation by the second centrifuge 9. Then, the operations of heat exchange, water washing, and oil-water separation are repeated. After washing three times, the obtained oil phase is the polymer solution after demetallization.

[0159] Example 3 In the demetallization unit, after the polymer solution obtained in step (2) is cooled by the first heat exchanger 17, the pressure is reduced by the pressure control valve 20, and then it enters the termination and complexation equipment 5. Under intense stirring conditions, an ethanol solution of maleic anhydride with a concentration of 0.5 mol / L in the complexing agent storage tank 6 is continuously injected into the termination and complexation equipment 5. The injection amount is 3% of the volume of the polymer solution in the termination and complexation equipment 5, and the residence time is 10 minutes. At the same time as the polymerization reaction is terminated, metal ions in the polymer solution are formed into water-soluble metal complexes to obtain a mixed solution. The mixed solution is subjected to oil-water separation by the first centrifuge 8. The obtained oil phase is heat-exchanged by the second heat exchanger 18, then put into the water washing tank 7 for washing. The polymer solution after washing is subjected to oil-water separation by the second centrifuge 9. Then, the operations of heat exchange, water washing, and oil-water separation are repeated. After washing twice, the obtained oil phase is the polymer solution after demetallization.

[0160] Example 4 In the de-metallization unit, after the polymer solution obtained in step (2) is cooled by the first heat exchanger 17, the pressure is reduced by the pressure control valve 20, and then it enters the termination complexing equipment 5. Under intense stirring conditions, a cis-butenedioic acid acetone solution with a concentration of 1 mol / L in the complexing agent storage tank 6 is continuously injected into the termination complexing equipment 5. The injection amount is 1% of the volume of the polymer solution in the termination complexing equipment 5, the residence time is 20 minutes. At the same time as the polymerization reaction is terminated, metal ions in the polymer solution are formed into water-soluble metal complexes to obtain a mixed solution. The mixed solution is subjected to oil-water separation by the first centrifuge 8. The obtained oil phase is heat-exchanged by the second heat exchanger 18, then put into the water washing tank 7 for water washing. The polymer solution after water washing is subjected to oil-water separation by the second centrifuge 9. Then, the operations of heat exchange, water washing, and oil-water separation are repeated. After washing with water 4 times, the obtained oil phase is the polymer solution after de-metallization.

[0161] Example 5 In the de-metallization unit, after the polymer solution obtained in step (2) is cooled by the first heat exchanger 17, the pressure is reduced by the pressure control valve 20, and then it enters the termination complexing equipment 5. Under intense stirring conditions, an aqueous solution of 2,3-dimethylmaleic anhydride with a concentration of 2 mol / L in the complexing agent storage tank 6 is continuously injected into the termination complexing equipment 5. The injection amount is 1.5% of the volume of the polymer solution in the termination complexing equipment 5, the residence time is 30 minutes. At the same time as the polymerization reaction is stopped, metal ions in the polymer solution are formed into water-soluble metal complexes to obtain a mixed solution. The mixed solution is subjected to oil-water separation by the first centrifuge 8. The obtained oil phase is heat-exchanged by the second heat exchanger 18, then put into the water washing tank 7 for water washing. The polymer solution after water washing is subjected to oil-water separation by the second centrifuge 9. The obtained oil phase is the polymer solution after de-metallization.

[0162] Example 6 In the de-metallization unit, after the polymer solution obtained in step (2) is cooled down by the first heat exchanger 17, the pressure is reduced by the pressure control valve 20, and then it enters the termination and complexation equipment 5. Under intense stirring conditions, a 2,3-dimethylmaleic anhydride ethanol solution with a concentration of 3 mol / L in the complexing agent storage tank 6 is continuously injected into the termination and complexation equipment 5. The injection amount is 1% of the volume of the polymer solution in the termination and complexation equipment 5, and the residence time is 40 minutes. At the same time as stopping the polymerization reaction, metal ions in the polymer solution are formed into water-soluble metal complexes to obtain a mixed solution. The mixed solution is subjected to oil-water separation by the first centrifuge 8, and the obtained oil phase is heat-exchanged by the second heat exchanger 18, and then put into the water washing tank 7 for water washing. The polymer solution after water washing is subjected to oil-water separation by the second centrifuge 9, and then the operations of heat exchange, water washing, and oil-water separation are repeated. After washing with water 5 times, the obtained oil phase is the polymer solution after de-metallization.

[0163] Example 7 In the de-metallization unit, after the polymer solution obtained in step (2) is cooled down by the first heat exchanger 17, the pressure is reduced by the pressure control valve 20, and then it enters the termination and complexation equipment 5. Under intense stirring conditions, a 2,3-dimethylmaleic anhydride acetone solution with a concentration of 5 mol / L in the complexing agent storage tank 6 is continuously injected into the termination and complexation equipment 5. The injection amount is 5% of the volume of the polymer solution in the termination and complexation equipment 5, and the residence time is 60 minutes. At the same time as stopping the polymerization reaction, metal ions in the polymer solution are formed into water-soluble metal complexes to obtain a mixed solution. The mixed solution is subjected to oil-water separation by the first centrifuge 8, and the obtained oil phase is heat-exchanged by the second heat exchanger 18, and then put into the water washing tank 7 for water washing. The polymer solution after water washing is subjected to oil-water separation by the second centrifuge 9, and then the operations of heat exchange, water washing, and oil-water separation are repeated. After washing with water 3 times, the obtained oil phase is the polymer solution after de-metallization.

[0164] Comparative Example 1 This comparative example provides a continuous solution polymerization method, which was basically the same as the continuous solution polymerization method provided in Example 2 except for the de-metallization step.

[0165] The demetallization step of this comparative example was as follows.

[0166] In the demetallization unit, after the polymer solution obtained in step (2) was cooled by the first heat exchanger 17, the pressure was reduced by the pressure control valve 20, and then it entered the termination complexation equipment 5. Under intense stirring conditions, an aqueous adipic acid solution with a concentration of 0.1 mol / L in the complexing agent storage tank 6 was continuously injected into the termination complexation equipment 5. The injection amount was 2.5% of the volume of the polymer solution in the termination complexation equipment 5, and the residence time was 5 minutes. At the same time as terminating the polymerization reaction, metal ions in the polymer solution were formed into water-soluble metal complexes to obtain a mixed solution. The mixed solution was subjected to oil-water separation by the first centrifuge 8, and the obtained oil phase was heat-exchanged by the second heat exchanger 18, and then put into the water washing tank 7 for water washing. The polymer solution after water washing was subjected to oil-water separation by the second centrifuge 9, and then the operations of heat exchange, water washing, and oil-water separation were repeated. After washing with water three times, the obtained oil phase was the polymer solution after demetallization.

[0167] Comparative Example 2 This comparative example provided a continuous solution polymerization method, which was basically the same as the continuous solution polymerization method provided in Example 2 except for the demetallization step.

[0168] The demetallization step of this comparative example was as follows.

[0169] In the demetallization unit, after the polymer solution obtained in step (2) is cooled by the first heat exchanger 17, the pressure is reduced by the pressure control valve 20, and then it enters the termination and complexation equipment 5. Under intense stirring conditions, an aqueous citric acid solution with a concentration of 0.1 mol / L in the complexing agent storage tank 6 is continuously injected into the termination and complexation equipment 5. The injection amount is 2.5% of the volume of the polymer solution in the termination and complexation equipment 5, and the residence time is 5 minutes. At the same time as the polymerization reaction is terminated, metal ions in the polymer solution are formed into water-soluble metal complexes to obtain a mixed solution. The mixed solution is subjected to oil-water separation by the first centrifuge 8, and the obtained oil phase is heat-exchanged by the second heat exchanger 18, and then put into the water washing tank 7 for water washing. The polymer solution after water washing is subjected to oil-water separation by the second centrifuge 9, and then the operations of heat exchange, water washing, and oil-water separation are repeated. After washing with water three times, the obtained oil phase is the polymer solution after demetallization.

[0170] Comparative Example 3 This comparative example provides a continuous solution polymerization method, which is basically the same as the continuous solution polymerization method provided in Example 2 except for the demetallization step. In the demetallization unit of this comparative example, components such as the termination and complexation equipment 5, the complexing agent storage tank 6, and the water washing tank 7 are not installed. After the polymer solution is cooled and the pressure is reduced, it is adsorbed and separated by an adsorption column filled with an adsorbent.

[0171] The demetallization step of this comparative example was as follows.

[0172] Take 250 mL of powdered aluminum trioxide (the same as the powdered aluminum trioxide in Example 2), heat it to 100 °C, add 100 mL of an aqueous maleic acid solution with a concentration of 0.005 mol / L, continue to stir for 2 hours, then filter, take the filter residue, dry it at 120 °C for 8 hours to obtain maleic acid pretreated aluminum trioxide powder. The bulk density of the maleic acid pretreated aluminum trioxide powder is 0.41 g / mL, the specific surface area is 212 m 2 / g, and the pore volume is 0.42 mL / g.

[0173] In the de-metallization unit, after cooling down and reducing the pressure of the polymer solution obtained in step (2), under the temperature and pressure conditions of 50°C and 0.2 MPa, for 0.5 h -1 at a volumetric space velocity of, it is adsorbed and separated by an adsorption column filled with aluminum trioxide powder pretreated with the maleic acid to obtain a polymer solution after de-metallization.

[0174] Comparative Example 4 This comparative example provides a continuous solution polymerization method, which was basically the same as the continuous solution polymerization method provided in Example 2 except for the de-metallization step.

[0175] The de-metallization step of this comparative example was as follows.

[0176] In the de-metallization unit, after the polymer solution obtained in step (2) was cooled down by the first heat exchanger 17, the pressure was reduced by the pressure control valve 20, and then it entered the termination and complexation equipment 5. Under intense stirring conditions, an aqueous fumaric acid solution with a concentration of 0.1 mol / L in the complexing agent storage tank 6 was continuously injected into the termination and complexation equipment 5. The injection amount was 2.5% of the volume of the polymer solution in the termination and complexation equipment 5, and the residence time was 5 minutes. At the same time as terminating the polymerization reaction, metal ions in the polymer solution were formed into water-soluble metal complexes to obtain a mixed solution. The mixed solution was subjected to oil-water separation by the first centrifuge 8. The obtained oil phase was heat-exchanged by the second heat exchanger 18, and then put into the water washing tank 7 for water washing. The polymer solution after water washing was subjected to oil-water separation by the second centrifuge 9, and then the operations of heat exchange, water washing, and oil-water separation were repeated. After washing with water three times, the obtained oil phase was the polymer solution after de-metallization.

[0177] Test Example 1 The results of detecting the metal content and VOC content in the polymer particles prepared in the above Examples 2 to 7 and Comparative Examples 1 to 4 are shown in Table 2 below. The polymer solutions obtained in step (2) in the above Examples 2 to 7 and Comparative Examples 1 to 4 were not treated in the de-metallization unit of step (3) and were directly treated in the subsequent devolatilization unit and extrusion granulation unit, and then polymer particles were obtained. The results of detecting the metal content therein are shown in Table 2 below.

[0178] Here, the metal content in the polymer particles was measured using the incineration method, and the specific steps were the usual technical means in this field. The incineration method used in this test example specifically involved putting 100 g of polymer particles into a muffle furnace, heating up to 650°C in 1 hour by programmed temperature increase, then holding at a constant temperature for 2 hours so that the polymer burns sufficiently, and then cooling to room temperature. The ash remaining after incineration was added to 5 mL of hydrochloric acid solution (the mass fraction of the hydrochloric acid solution is 19%). After the ash was completely dissolved, the metal content in the solution was analyzed by ICP-MS.

[0179] The VOC content in the polymer particles was measured by the oven method, and the specific steps were the usual technical means in this field. The operating conditions of the oven method adopted in this test example included vacuum drying at 100°C.

[0180]

Table 2

Claims

1. Step (1): subjecting the raw materials for the polymerization reaction to a polymerization reaction to obtain a polymer solution; Step (2): mixing the polymer solution with a complexing agent and reacting them to obtain a mixture, washing the mixture with water to obtain a polymer solution after metal removal; Step (3): subjecting the polymer solution after metal removal to devolatilization to obtain a polymer after devolatilization and volatile components; Step (4): subjecting the polymer after devolatilization to extrusion granulation to obtain polymer particles; A continuous solution polymerization method comprising: The complexing agent includes one or more combinations of dicarboxylic acids and their derivatives. The dicarboxylic acid contains a carbon-carbon double bond, and two carboxyl groups are arranged on the same side of the carbon-carbon double bond, and has a cis structure in the spatial arrangement. A continuous solution polymerization method.

2. In Step (1), the raw materials for the polymerization reaction include an olefin monomer, a solvent, and a catalyst system; the raw materials for the polymerization reaction optionally further include a scavenger; the olefin monomer includes one or more combinations of ethylene, α-olefin, and cycloolefin; the solvent includes one or more combinations of C6-C12 alkanes, cycloalkanes, and aromatic hydrocarbons; the catalyst system includes a metallocene catalyst system; The continuous solution polymerization method according to Claim 1.

3. In Step (1), the temperature of the polymerization reaction is 70-180°C, the pressure of the polymerization reaction is 0.5-1.5 MPa, and the time of the polymerization reaction is 30-120 min. The continuous solution polymerization method according to Claim 1.

4. Before Step (1), it further includes a raw material preparation step for the olefin monomer and the solvent. The raw material preparation step includes mixing and preheating the olefin monomer and the solvent. The continuous solution polymerization method according to Claim 2.

5. The raw material preparation step includes: mixing with a solvent to dissolve ethylene to obtain a mixture of ethylene and the solvent; mixing with a solvent to dissolve a comonomer to obtain a mixture of the comonomer and the solvent; mixing and preheating the mixture of ethylene and the solvent with the mixture of the comonomer and the solvent to obtain a mixture of the olefin monomer and the solvent; including the temperature for dissolving ethylene is 20-90°C, and the pressure is 0.1-5.0 MPa. The temperature for mixing the comonomer and the solvent is 25 to 75°C, and the pressure is 0.05 to 0.2 MPa. The temperature of the mixture of the olefin monomer and the solvent obtained after mixing and preheating is 60 to 160°C. The continuous solution polymerization method according to claim 4.

6. The continuous solution polymerization method according to claim 1, wherein in step (2), the dicarboxylic acid has a structure represented by the following formula I. 【Chemical 1】 (In formula I, R １ , R ２ are the same or different, and R １ and R ２ are each independently selected from an H atom, a linear or branched alkyl group having 1 to 10 carbon atoms.)

7. The continuous solution polymerization method according to claim 1, wherein in step (2), the derivative of the dicarboxylic acid includes one or a combination of two or more of an acid anhydride, an acid halide, an amide, an ester, and a nitrile formed from the dicarboxylic acid.

8. The continuous solution polymerization method according to claim 7, wherein in step (2), the derivative of the dicarboxylic acid includes an acid anhydride of the dicarboxylic acid, and the acid anhydride of the dicarboxylic acid has a structure represented by the following formula II. 【Chemical 2】 (In formula II, R １ , R ２ are the same or different, and R １ and R ２ are each independently selected from an H atom, a linear or branched alkyl group having 1 to 10 carbon atoms.)

9. In step (2), the mixing ratio of the polymer solution and the complexing agent is 1 g of polymer: 10 －３ to 10 －５ mol, and the continuous solution polymerization method according to claim 1.

10. The continuous solution polymerization method according to claim 1, wherein in step (2), the complexing agent is mixed with the polymer solution as a solution, and the concentration of the complexing agent solution is 0.1 to 10 mol / L. The solvent in the complexing agent solution includes one or a combination of two or more of water, alcohols, ketones, and hydrocarbons. The continuous solution polymerization method according to claim 1.

11. The continuous solution polymerization method according to claim 1, wherein in step (2), the temperature for mixing and reacting the polymer solution and the complexing agent is 60 to 150°C. The reaction time between the polymer solution and the complexing agent is 2 to 120 minutes. The continuous solution polymerization method according to claim 1.

12. Step (2) specifically includes: After heat-exchanging and depressurizing the polymer solution, putting it into an end-complexing device, injecting the complexing agent into the end-complexing device, and at the same time ending the polymerization reaction and forming metal ions in the polymer solution into a water-soluble metal complex to obtain a mixed solution. After separating the oil and water of the mixed solution, heat-exchanging the obtained oil phase, washing it with water, performing oil-water separation after washing, and the obtained oil phase is the polymer solution after demetallization. including The continuous solution polymerization method according to claim 1.

13. The continuous solution polymerization method according to claim 12, wherein the temperature of the water washing is 30 to 60°C, and the volume ratio of the amount of water used for the water washing to the volume of the oil phase is 1 to 20:

1.

14. The continuous solution polymerization method according to claim 1, wherein in step (3), the polymer solution after demetallization is devolatilized at a pressure of 10 to 50 bar and a temperature of 210 to 280°C.

15. In step (4), the equipment for extruding and pelletizing the polymer after devolatilization includes an extrusion granulator. A degassing port is installed at the extrusion end of the extrusion granulator. After extrusion, the volatile components in the polymer after devolatilization are further removed, and then it passes through the granulation end of the extrusion granulator to be granulated, obtaining polymer particles. The polymer particles obtained in step (4) have a VOC content of less than 50 ppm. The continuous solution polymerization method according to claim 1.

16. The continuous solution polymerization method further includes step (5) of rectifying the volatile components obtained in step (3) and also rectifying the volatile components removed by extrusion granulation in step (4). The rectification uses a rectification column. The operating conditions of the rectification column are that the bottom temperature is 130 - 150 °C, the bottom pressure is 10 - 30 Torr, the maximum top temperature is 90 - 110 °C, and the reflux ratio is 1 - 25. The continuous solution polymerization method according to claim 1.

17. Specifically, step (5) includes putting the volatile components obtained in step (3) and the volatile components removed by extrusion granulation in step (4) into a rectification column for rectification. The ethylene flowing out from the top of the rectification column enters a reflux tank. After performing exhaust and gas-liquid separation, ethylene is obtained, and unreacted comonomer flowing out from the side wall of the rectification column and the solvent flowing out from the bottom of the rectification column are obtained. After performing gas-liquid separation in the reflux tank, the liquid phase obtained is returned to the rectification column to perform rectification again. The continuous solution polymerization method according to claim 16.

18. Step (6): Further including recycling one or more of the ethylene, unreacted comonomer, and solvent obtained in step (5). The continuous solution polymerization method according to claim 17.

19. A continuous solution polymerization system for realizing the continuous solution polymerization method according to claim 1, including at least a polymerization reaction unit, a demetallization unit, a devolatilization unit, and an extrusion granulation unit. The polymerization reaction unit includes at least a polymerization reaction tank, and at least a polymerization reaction raw material inlet and a polymer solution outlet are provided in the polymerization reaction tank. The demetallization unit includes at least an end-complexing facility and a water washing tank. At least a polymer solution inlet, a complexing agent inlet, and a mixed liquid outlet are provided in the end-complexing facility. An oil phase inlet, a water inlet, and a polymer solution outlet are provided in the water washing tank. The devolatilization unit includes at least a flash tank, and the flash tank is provided with at least a material inlet, a polymer outlet after devolatilization, and a volatiles outlet. The extrusion granulation unit includes at least an extrusion granulator. The polymer solution outlet of the polymerization reaction tank is connected to the polymer solution inlet of the termination and complexation equipment via a line, the mixed liquid outlet of the termination and complexation equipment is connected to the oil phase inlet of the water washing tank via a line, the polymer solution outlet of the water washing tank is connected to the material inlet of the flash tank via a line, and the polymer outlet after devolatilization of the flash tank is connected to the extrusion granulator via a line, a continuous solution polymerization system.

20. The polymerization reaction raw material inlet of the polymerization reaction tank is installed at the bottom of the polymerization reaction tank, and the polymer solution outlet is installed at the top of the polymerization reaction tank. The polymerization reaction raw material inlet of the polymerization reaction tank includes an olefin monomer and solvent inlet, and a catalyst system and optionally a scavenger inlet. A heat exchanger and a pressure control valve are installed in the line connecting the polymer solution outlet of the polymerization reaction tank and the polymer solution inlet of the termination and complexation equipment. The continuous solution polymerization system according to claim 19.

21. The polymer solution inlet of the termination and complexation equipment is installed at the bottom of the termination and complexation equipment, the complexing agent inlet is installed at the bottom of the termination and complexation equipment, and the mixed liquid outlet is installed at the top of the termination and complexation equipment. The demetallization unit further includes a complexing agent storage tank, and the complexing agent storage tank is connected to the complexing agent inlet of the termination and complexation equipment via a line. A centrifuge is installed in the line connecting the mixed liquid outlet of the termination and complexation equipment and the oil phase inlet of the water washing tank. A centrifuge is installed in the line connecting the polymer solution outlet of the water washing tank and the material inlet of the flash tank. The continuous solution polymerization system according to claim 19.

22. The material inlet of the flash tank is installed on the side wall of the flash tank, the polymer outlet after devolatilization is installed at the bottom of the flash tank, and the volatiles outlet is installed at the top of the flash tank. The number of flash tanks is one or more than two. When using more than two flash tanks, the more than two flash tanks are provided in series. To provide the heat required for the devolatilization process, each flash tank is equipped with a heat exchanger, and the heat exchanger is installed in a line connected to the material inlet of the flash tank. Moreover, to convey the polymer after devolatilization, a conveying pump is installed in each line connected to the polymer outlet after devolatilization of the flash tank. The continuous solution polymerization system according to claim 19.

23. A degassing port is provided at the extrusion end of the extrusion granulator. The number of the degassing ports is two, and they are respectively installed in the middle and the end of the extrusion end of the extrusion granulator. The continuous solution polymerization system according to claim 19.

24. A vacuum degassing device is installed at the extrusion end of the extrusion granulator, and the vacuum degassing device is connected to the degassing port. The continuous solution polymerization system according to claim 23.

25. The extrusion granulator includes a twin-screw extrusion granulator, and the aspect ratio of the extrusion screw of the twin-screw extrusion granulator is 40 to 80:

1. The continuous solution polymerization system according to claim 19.

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