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 the last few 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, 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 de-metallization or de-ashing) is of the utmost importance.

[0004] Common decalcification methods used in the polymer industrialization process include aqueous extraction, coagulation and sedimentation, and complexing adsorption. Of these, complexing adsorption is the most widely used decalcification method in polymer industrial production, offering advantages such as a simple process, large adsorption capacity, high removal efficiency, fewer interfering factors, and good stability. Complexing agents are broadly classified into two types: inorganic and organic. Inorganic complexing agents are generally easily decomposed at high temperatures and are only applicable to alkaline media, thus limiting their range of application. Organic complexing agents have a wide range of application, but it is usually difficult to reduce the metal content in the polymer solution to below 10 ppm. In addition, in the industrialization process, complexing and decalcification are generally performed using supported adsorbent fillers. Such adsorbents are solid fillers manufactured by immersing and roasting an alumina carrier and complexing agent material, and they have a low effective load capacity for the complexing agent, which limits their application to certain extent.

[0005] CN107011485A discloses a composite catalyst having three active centers and a method for producing a cycloolefin copolymer using the same. In this method for producing a cycloolefin copolymer, a composite catalyst (i.e., the main catalyst) having salicylene 2-mercaptoaniline titanium trichloride, racemic vinyl (diindenyl) zirconium dichloride, and dichlorozircone as three active centers is used in a batch polymerization reactor, and a toluene solution of methylaluminoxane (MAO) is used as a co-catalyst. Cycloolefin is used as the comonomer, and ethylene is added by replenishment metering during the polymerization process, and the polymerization reaction is carried out while controlling the pressure to 0.1 MPa. After the reaction is complete, the reaction solution is precipitated in ethanol containing 15% (v / v%) hydrochloric acid (consisting of 150 mL of hydrochloric acid and 1000 mL of ethanol), filtered, the filtered cake is washed with ethanol (300 mL), and then dried to a constant weight to obtain the cycloolefin copolymer. However, this production method does not relate to the removal of metals from the polymer.

[0006] CN108752526A discloses a catalyst system for producing ethylene and / or α-olefin and cycloolefin copolymers. The catalyst system comprises a main catalyst and a co-catalyst, the main catalyst being a metallocene compound and the co-catalysts being an organoboron compound and an alkylaluminum. A method for producing ethylene and / or α-olefin and cycloolefin copolymers using this catalyst system includes the steps of placing an inert organic solvent, ethylene / α-olefin, and cycloolefin into separate reactors under conditions of a temperature of 40 to 100°C and a pressure of 1 to 30 bar, dissolving the ethylene and / or α-olefin in the inert organic solvent to saturation, and then sequentially adding a triisobutylaluminum solution, a metallocene catalyst solution, and an organoboron compound solution to carry out a polymerization reaction. The use of this co-catalyst allows for more efficient polymerization of cycloolefin copolymers than MAO, MMAO, and dMAO, reduces the metal content in the polymerization product, and significantly lowers post-processing costs.

[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 comprising an alkylaluminum co-catalyst 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 of the first mixture obtained in step (1) to 4-9 with a pH adjuster to obtain a second mixture, and (3) separating and removing the precipitate from the second mixture obtained in step (2) by centrifugation, where the amount of water added is 0.1-20% by volume relative to the volume of the copolymer solution. This method is highly effective in removing residual catalyst from the copolymer solution and is low-cost. The pH adjuster used in this method is an alkali metal hydroxide and / or an alkaline earth metal hydroxide, preferably sodium hydroxide. However, this method does not have a sufficiently high rate of metal removal, and the resulting polymer product cannot meet the requirements for medical-grade and optical-grade polymer standards.

[0008] US4716207A discloses a method for producing a knotted polymer by preparing copolymer chains and coupling them with a coupling agent. The demineralization step in this method mainly involves supplying the copolymer product from the reactor to a demineralization section through a conduit, where the catalyst residue reacts with water to form hydrocarbon-insoluble hydroxides, and then extracting the hydroxides with dilute acid to remove vanadium and aluminum compound residues. However, this method does not adequately remove metals, and the resulting polymer products cannot meet the requirements for medical-grade and optical-grade polymers.

[0009] CN110016092A discloses a method for the continuous production of polyolefins, particularly polyolefin elastomers or mixtures thereof. This method involves prepolymerization using a tank reactor, which improves the viscosity of the reaction system and facilitates the subsequent operation of a screw reactor. Static mixing polymerization is then performed using a static mixer to further increase the viscosity of the system and extend the reaction residence time. Simultaneously, extrusion polymerization is carried out using a reactive screw extruder, achieving a high conversion rate and high viscosity polymerization reaction. This method is suitable for the production of various types of polyolefins, and is particularly suitable for the preparation of polyolefin elastomers or mixtures thereof. However, this method does not involve the removal of metals from the polymer, and the resulting polymer products cannot meet the requirements for medical-grade and optical-grade polymer specifications.

[0010] CN113207283A discloses a system for solution polymerization. The system comprises a reactor system, a plurality of defoliation vessels, and a liquid-liquid separator. The reactor system receives a reverse solvent, rather than a solvent for the polymer, to lower the system's low critical solution temperature (LCST), along with a monomer and a solvent, and reacts them to form a polymer. The plurality of defoliation vessels are located downstream of the reactor system, receive the polymer solution from the reactor system, and each defoliation vessel operates at a lower pressure than the preceding defoliation vessel. The liquid-liquid separator receives the polymer solution from the reactor system and facilitates the separation of the polymer from volatiles by lowering the pressure and temperature of the polymer solution in the liquid-liquid separator. However, the system does not relate to a process for removing metals from the polymer, and the resulting polymer products cannot meet the requirements of medical-grade and optical-grade polymer standards.

[0011] US20120088893A1 discloses a solution polymerization method. The method includes: step (A) polymerizing one or more monomers in the presence of a solvent including 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 reducing the pressure of the polymer solution in a controlled manner before or inside 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. This solution polymerization process is primarily used to solve the problem of solvent separation in polymer preparation processes and does not relate to a demetallation process.

[0012] US4992529A discloses a method for removing metals using mixed acids. This method is characterized by the reaction of a monocarboxylic acid with a metal in the organic phase to produce a carboxylate salt that does not dissolve in the organic phase, the reaction of this carboxylate salt with an inorganic acid in the mixed acid to produce an inorganic salt that dissolves in the aqueous phase, the reduction of the carboxylic acid to return to the organic phase, and the subsequent reaction with the metal in the polymer solution to produce a carboxylate salt, and the repetition of this process until the metal in the polymer solution has completely moved to the aqueous phase, thereby achieving the removal of the remaining metal. Here, the carboxylic acid acts as a phase-transfer catalyst. Although the concept of this method is novel, the removal effect is undesirable and a large amount of water is required.

[0013] CN114534694A discloses a complexed adsorption filler, a method for producing the same, and its use. The adsorption filler is a molecular sieve filler supporting a quinolinol compound, and an organic acid can be supported on the molecular sieve supporting the quinolinol compound. The adsorption filler can effectively remove residual catalysts in polyolefin solutions and has advantages such as a fast demineralization rate, high adsorption capacity, and low pressure loss, making it suitable for catalyst removal in various olefin solution polymerization processes. However, the manufacturing process for the adsorption filler is complex and cumbersome, and at the same time, due to the low amount of quinolinol supported, the adsorption capacity of the adsorption filler is low and the operating cost is high.

[0014] CN114989331A discloses a method for complexing and demineralizing a polyolefin solution. The method comprises (1) adding diminazene to a polyolefin solution to complexe and adsorb metal ions in the solution and form a complex, and (2) passing the polyolefin solution containing the complex through an adsorption column packed with porous metal oxides to perform adsorption treatment and obtain a purified polyolefin solution. This demineralization method can efficiently remove residual metals from the polyolefin solution, is simple in process, exhibits low filler swelling and low system pressure drop, and has a long service life for the demineralized filler, a long adsorption column replacement cycle, and significantly reduces processing costs. However, diminazene has only average complexing ability with metals, resulting in a low metal removal rate, and is particularly problematic for high metallic aluminum content in polymers.

[0015] CN102875702A discloses a method for removing metals from polymers. This method employs a process in which an organic base, such as n-butyllithium or phenyllithium, is added to polymer latex, followed by the addition of an oxidizing agent, the reaction is followed by washing with water, and finally centrifugation, in order to achieve the objective of removing residual metals from latex. While this method is highly efficient in removing residual metals from polymers, the use of organic bases and the introduction of some metal ions result in high costs for raw material input and removal of residual catalysts, as well as high equipment requirements due to the addition of organic bases.

[0016] CN114392724A discloses a deashcrete adsorbent specifically for polyolefins, as well as its manufacturing method and use. The deashcrete adsorbent is prepared by using pyridine-3-carboxylic acid as a complexing agent and supporting it on an oxide carrier. This deashcrete adsorbent can efficiently remove residual metals from polyolefin solutions, significantly reducing the amount of residual metals in polyolefin products. Compared to conventional chelate adsorption methods, it has advantages such as a faster deashcrete rate, higher adsorption capacity, lower swelling, and lower solution pressure loss. However, the manufacturing process for this deashcrete adsorbent is complex and cumbersome, and because the amount of pyridine-3-carboxylic acid supported is low, the adsorption capacity of the adsorbent is low, resulting in high operating costs.

[0017] CN113856637A discloses a method for removing residual metals in the COC and COP production process using a complexing adsorption filler. Compared to conventional adsorption resins, this adsorption filler has advantages such as a fast metal demineralization rate and a large adsorption capacity, while simultaneously not exhibiting swelling. The adsorption filler is manufactured by reacting silica solid, a solvent, and phosphorus tribromide in a specified proportion to obtain silica bromide solid, further reacting it with an appropriate amount of diethyl iminodate to obtain a yellow solid, acidifying it with hydrochloric acid, and then obtaining the adsorption filler. However, the manufacturing process for this adsorption filler is complex and cumbersome, and the heavy metal removal rate is not high.

[0018] US5073621A discloses a demetallation method using water as a solubilizer. This method can suitably remove metals from polymer latex by first dissolving a dicarboxylic acid in water and then adding it to the polymer latex. However, this method is prone to causing emulsification of the latex, which is unfavorable for the reaction between the dicarboxylic acid and metal ions, affecting the rate of metal removal and making the process difficult to control.

[0019] CN1067898A discloses a method for removing residual metal catalysts after the hydrogenation of a polymer. In this method, hydrogen peroxide is added as an oxidizing agent and sebacic acid as a precipitating agent to a hydrogenated butadiene-styrene random copolymer latex. The sebacic acid is then dissolved in an aqueous solution of diethylene glycol-butyl ether to form a sebacic acid solution, which significantly improves the metal removal effect from the latex. However, the sites of the two carboxyl groups of the dicarboxylic acid used in this method are not constant, resulting in poor complexing effect with the metal and thus a low metal removal rate.

[0020] Conventional demetallation techniques in polymer solution polymerization processes have drawbacks such as complex adsorbent preparation processes, long demetallation processes, and low removal efficiency. Therefore, developing novel continuous solution polymerization methods and systems is one of the urgent issues that needs to be addressed in this field. [Overview of the project]

[0021] To solve the above technical problems, the present invention aims to provide a continuous solution polymerization method and system. The method and system of the present invention have advantages such as being able to remove residual metals in the polymer deeply and efficiently, as well as having a short process, low production costs, and the ability to operate continuously for long periods.

[0022] To achieve the above objective, a first aspect of the present invention is: Step (1): Polymerize the raw materials for the polymerization reaction to obtain a polymer solution. Step (2): After mixing the polymer solution with the complexing agent and allowing it to react, a mixture is obtained, and the mixture is washed with water to obtain the demetallated polymer solution. Step (3): After demetallation of the polymer solution, obtain the devolatile polymer and volatile components. Step (4): After the defoliated polymer is extruded and granulated, polymer particles are obtained. A continuous solution polymerization method comprising, The present invention provides a continuous solution polymerization method in which the complexing agent comprises one or more dicarboxylic acids and their derivatives, the dicarboxylic acid comprising a carbon-carbon double bond and having two carboxyl groups arranged on the same side of the carbon-carbon double bond, and having a cis structure in spatial arrangement.

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

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

[0025] In some specific embodiments of the present invention, the solvent includes one or a combination of multiple types such as C6 - C12 alkanes, cycloalkanes, and aromatic hydrocarbons. Preferably, the solvent includes one or a combination of multiple types such as cyclohexane, methylcyclohexane, n-hexane, and toluene.

[0026] In some specific embodiments of the present invention, the catalyst system includes a metallocene catalyst system containing a main catalyst which is a metallocene compound and a cocatalyst. Generally, the metallocene compound includes a complex formed by coordination of a group IVB, VB, VIB group 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 commonly used or disclosed in prior art documents in the field of olefin polymerization. According to a specific embodiment of the present invention, the cocatalyst includes one or a combination of multiple types such as alkylaluminoxane and / or organoborate. Specifically, the alkylaluminoxane includes one or a combination of multiple types such as methylaluminoxane (MAO), modified methylaluminoxane (MMAO), ethylaluminoxane (EAO), and isobutylaluminoxane (i-BAO). The organoborate includes one or a combination of multiple types such as tris(pentafluorophenyl)boron, N,N-dimethyl-tetrakis(pentafluorophenyl)boron, and tris(pentafluorophenyl)carbon-tetrakis(pentafluorophenyl)boron.

[0027] In some specific embodiments of the present invention, the cleaning agent includes alkylaluminum and / or alkylaluminum halides, and specifically, may include one or more combinations of trimethylaluminum, triethylaluminum, tri-n-propylaluminum, triisobutylaluminum, tri-n-butylaluminum, triisobutylaluminum, tri-n-pentylaluminum, tri-n-hexylaluminum, triisohexylaluminum, diethylmethylaluminum, dimethylethylaluminum, monochlorodimethylaluminum, dichloromonomethylaluminum, monochlorodiethylaluminum, dichloromonoethylaluminum, monochlorodi-n-propylaluminum, dichloromono-n-propylaluminum, monochlorodiisobutylaluminum, dichloromonoisobutylaluminum, monochlorodi-n-butylaluminum, dichloromono-n-butylaluminum, monochlorodiisopentylaluminum, dichloromonoisopentylaluminum, monochlorodi-n-hexylaluminum, dichloro-n-hexylaluminum, monochloroisohexylaluminum, and dichloromonoisohexylaluminum. Preferably, the cleaning agent includes triisobutylaluminum and / or triethylaluminum.

[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 for the polymerization reaction can usually be adjusted according to different production needs and different target products of those skilled in the art, and the present invention does not particularly limit the mixing ratio.

[0029] In the above-described 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-described 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-described continuous solution polymerization method, preferably, in step (1), the time of the polymerization reaction is 30 to 120 minutes, and 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 reactor. The main catalyst, co-catalyst, cleaning agent, olefin monomer, and solvent in the metallocene catalyst system can be introduced into the polymerization reactor from the bottom to carry out the polymerization reaction. Specifically, the polymerization reactor is equipped with a stirrer, such as a paddle mixer. The polymerization reaction process can employ a full-clave operation method, and the polymer solution obtained after the reaction flows out from the top of the polymerization reactor. A pressure control valve for controlling the polymerization reaction pressure may also be provided in the polymer solution transfer line of the polymerization reactor. At the same time, the polymerization reaction temperature can be controlled by the jacket of the polymerization reactor using a high-temperature oil bath system. Furthermore, cooling coils are not installed in the polymerization reactor to prevent the polymer from adhering to the tube walls of the cooling coils.

[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%, and 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-described continuous solution polymerization method, preferably, the resulting polymer may include one or more combinations of cycloolefin copolymers (COC), cycloolefin polymers (COP), polyethylene, polypropylene, polyolefin plastomers (POP), and polyolefin elastomers (POE).

[0036] According to specific embodiments of the present invention, preferably, the continuous solution polymerization method further comprises a raw material preparation step of preparing an olefin monomer and a solvent prior to step (1), the raw material preparation step comprising mixing and preheating the olefin monomer and the solvent. More preferably, the raw material preparation step may include mixing with the solvent to dissolve ethylene to obtain a mixture of ethylene and the solvent; mixing with the solvent to dissolve a comonomer to obtain a mixture of comonomer and the solvent; and mixing the mixture of ethylene and the solvent and the mixture of comonomer and the solvent, preheating, and then obtaining a mixture of olefin monomer and the solvent.

[0037] In some specific embodiments of the present invention, the temperature at which ethylene is dissolved is 20 to 90°C, and the pressure is 0.1 to 5.0 MPa, preferably, the temperature at which ethylene is dissolved 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 at which the comonomer and solvent are mixed is 25 to 75°C and the pressure is 0.05 to 0.2 MPa, preferably the temperature at which the comonomer and solvent are mixed 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 olefin monomer and 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 relating to the olefin monomer and solvent may specifically include: storing ethylene in an ethylene buffer tank; then injecting the ethylene from the ethylene buffer tank into an ethylene dissolution tank; mixing it with a solvent in the ethylene dissolution tank to dissolve the ethylene and obtain a mixture of ethylene and solvent; mixing a comonomer and a solvent in a comonomer storage tank to dissolve the comonomer and obtain a mixture of comonomer and solvent; and then mixing the ethylene and solvent mixture and the comonomer and solvent mixture in a line according to the molar ratio of ethylene to comonomer (a common design by those skilled in the art), preheating in a preheater, and obtaining a mixture of olefin monomer and 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 olefin monomer and solvent is then entered into a polymerization reactor, where it comes into contact with a catalyst system and a cleaning agent, which may or may not be added, to carry out 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. [ka] (In Formula I, R1 and R2 are the same or different, and R1 and R2 are each independently selected from an H atom and a linear or branched alkyl group of C1 to C10, preferably R1 and R2 are the same or different, and R1 and R2 are each independently selected from an H atom and a linear or branched alkyl group of C1 to C5.)

[0043] In the above continuous solution polymerization method, preferably in step (2), the derivative of the dicarboxylic acid includes one or more combinations of acid anhydrides, acid halides, amides, esters, and nitriles 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. [ka] (In Formula II, R1 and R2 are the same or different, and R1 and R2 are each independently selected from a hydrogen atom and a linear or branched alkyl group of C1 to C10, preferably R1 and R2 are the same or different, and R1 and R2 are each independently selected from a hydrogen atom and a linear or branched alkyl group of C1 to C5.)

[0045] In some specific embodiments of the present invention, in step (2), the dicarboxylic acid and its derivatives include one or more combinations of cis-butenioic acid (i.e., maleic acid), cis-butenioic anhydride (i.e., maleic anhydride), cis-methylbutenioic acid (i.e., 2-methylmaleic acid), cis-methylbutenioic 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, the step of demetallizing the polymer solution involves using a dicarboxylic acid and its derivative having a cis structure in spatial arrangement as a metal complexing agent. Such a dicarboxylic acid and its derivative having a cis structure react with metal ions in the polymer solution to form a stable water-soluble metal complex. Subsequently, the water-soluble metal complex is removed by washing with water, and the resulting oil phase is the demetallized polymer solution.

[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 the metal ion is shown by the following formula III. [ka] (In Formula III, R1 and R2 are the same or different, and R1 and R2 are each independently selected from an H atom, a C1-C10 linear or branched alkyl group, and M is a metal ion. Preferably, R1 and R2 are the same or different, and R1 and R2 are each independently selected from an H atom, a C1-C5 linear or branched alkyl group, and M is a metal ion.)

[0048] In the above continuous solution polymerization method, preferably, in step (2), the mixing ratio of the polymer solution and the complexing agent is 1g polymer:10 -3 ~10 -5 It is a molar complexing agent (i.e., a combination of one or more dicarboxylic acids and their 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 more combinations of water, alcohols, ketones, and hydrocarbons, and preferably one or more combinations of water, ethanol, and acetone.

[0050] In the above-described 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 rotational speed of the stirring can be adjusted by those skilled in the art according to the scale of production, preferably by stirring vigorously.

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

[0052] In the above-described continuous solution polymerization method, preferably, in step (2), the reaction time between the polymer solution and the complexing agent is 2 to 120 minutes, and 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 termination agent to deactivate the active centers in the polymer solution, efficiently terminating the polymerization reaction and preventing problems such as continued polymerization or explosion in subsequent processing steps. Therefore, the complexing agent solution used in the present invention, as both a metal complexing agent and a termination agent, synergistically and continuously advances the process of terminating the polymerization reaction and the process of complexing the metal, thereby improving process efficiency.

[0054] In some specific embodiments of the present invention, step (2) may specifically involve heat-exchanging and reducing the pressure of the polymer solution (from the polymerization reactor) and then placing it in a termination and complexing apparatus, injecting a complexing agent (specifically, the complexing agent solution) into the termination and complexing apparatus to stop the polymerization reaction and simultaneously cause the metal ions in the polymer solution to form water-soluble metal complexes to obtain a mixed solution, separating the oil and water from the mixed solution, heat-exchanging the obtained oil phase, washing it with water, and then separating the oil and water again, so that the obtained oil phase is the demetallated polymer solution.

[0055] In some specific embodiments of the present invention, the termination and 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. To prevent the polymer solution from vaporizing after being depressurized, a treatment method is employed in which the polymer solution discharged from the polymerization reactor is cooled before being depressurized. The polymer solution can be heat-exchanged and cooled using a heat exchanger.

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

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

[0059] In some specific embodiments of the present invention, the water temperature for the wash is 30 to 60°C, and the ratio of the amount of water used for the wash 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 wash.

[0060] Those skilled in the art will understand that when multiple washes are performed, oil-water separation is carried out after each wash to obtain the 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 a conventional centrifugal separator.

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

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

[0064] In some specific embodiments of the present invention, the equipment used to defolace the demetallated polymer solution may include a flash tank.

[0065] In some specific embodiments of the present invention, step (3) may specifically include heat-exchanging the demetallated polymer solution, placing it in a flash tank, and flash-separating the demetallated polymer solution to obtain the defolatable polymer and volatile matter. The defolatable polymer flows out from the bottom of the flash tank, and the volatile matter flows out from the top of the flash tank.

[0066] In some specific embodiments of the present invention, the demetallated polymer solution has a temperature of 210 to 360°C, preferably 220 to 300°C, after heat exchange. Heat exchange and heating of the demetallated polymer solution can be performed using a heat exchanger.

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

[0068] In some specific embodiments of the present invention, by defolantating the demetallated polymer solution using two or more series-connected flash tanks, volatile components remaining in the polymer solution can be removed as much as possible, and the volatile component content in the defolant polymer can be reduced to 5% or less. Each flash tank may be provided with a heat exchanger to provide the heat required for the defolant step, and at the same time, a gear pump or screw pump, applicable to the transport of high-viscosity fluids, may be attached to the bottom of each flash tank to transport the defolant polymer to downstream equipment.

[0069] In some specific embodiments of the present invention, the volatile matter obtained after the demetallation of the polymer solution is deflated includes one or more combinations of ethylene, unreacted comonomers, and solvents. Preferably, the weight percentage content of unreacted comonomers in the volatile matter obtained in step (3) is 20% to 55%, more preferably 30% to 45%.

[0070] In the above continuous solution polymerization method, preferably, in step (4), the equipment for extruding and granulating the deflated polymer includes an extruder, a degassing port is installed at the extrusion end of the extruder, and after extrusion, volatile components in the deflated polymer are further removed, and the polymer is further granulated at the granulation end of the extruder to obtain polymer particles. More preferably, a vacuum degassing device is installed at the extrusion end of the extruder, 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 defolatable polymer enters the extrusion granulator via a gear pump or screw pump installed at the bottom of the flash tank.

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

[0073] In some specific embodiments of the present invention, the number and location of the vents at the extrusion end of the extrusion granulator can be adjusted by those skilled in the art according to the actual situation, preferably, vents and vacuum vents connected to the vents are provided at the middle and end of the extrusion end of the extrusion granulator, respectively. According to specific embodiments of the present invention, if the number of vents in the extrusion granulator is too small, volatile components separated from the polymer latex are not removed from the extrusion granulator in a timely manner, and the volatile components dissolve back into the polymer latex, affecting the devolatilization efficiency. If the number of vents is too large, volatile components can be removed in a timely manner, but the heat exchange area of ​​the cylinder of the extrusion granulator is greatly reduced, decreasing the heat exchange capacity of the cylinder and thus reducing the devolatilization capacity of the extrusion granulator.

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

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

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

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

[0078] Specifically, step (5) may include placing the volatile matter obtained in step (3) and the volatile matter removed by extrusion granulation in step (4) into a rectification column and performing rectification, where the ethylene discharged from the top of the rectification column enters a reflux tank, where it is exhausted and gas-liquid separated to obtain ethylene, as well as unreacted comonomers discharged from the side walls of the rectification column and solvent discharged from the bottom of the rectification column, and returning the resulting liquid phase, after gas-liquid separation in the reflux tank, back into the rectification column for further rectification.

[0079] In specific embodiments of the present invention, preferably, the continuous solution polymerization method further includes step (6) of recycling one or more of the ethylene, unreacted comonomers, and solvent obtained in step (5). Specifically, step (6) may include compressing the ethylene separated in a 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 comonomers 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, ethylene obtained after gas-liquid separation in a reflux tank is compressed by a compressor and then returned to an ethylene buffer tank for recycling as one of the raw materials for a polymerization reaction. In the present invention, the recycled ethylene is referred to as recycled ethylene.

[0081] In some specific embodiments of the present invention, unreacted comonomers discharged from the side walls of the rectification column can be returned to a comonomer storage tank, and solvents discharged from the bottom of the rectification column can be returned to an ethylene dissolution tank and / or comonomer storage tank and recycled as one of the raw materials for polymerization reactions.

[0082] A second aspect of the present invention provides a continuous solution polymerization system for realizing the above-described continuous solution polymerization method, the system comprising at least a polymerization reaction unit, a demetallation unit, a defoliation unit, and an extrusion granulation unit.

[0083] Here, the polymerization reaction unit includes at least a polymerization reaction vessel, and the polymerization reaction vessel is provided with at least a polymerization reaction raw material inlet and a polymer solution outlet.

[0084] The demetallation unit includes at least a termination / complexing equipment and a washing tank, the termination / complexing equipment being provided with at least a polymer solution inlet, a complexing agent inlet and a mixed liquid outlet, and the washing tank being provided with an oil phase inlet, a water inlet and a polymer solution outlet.

[0085] The defoliation unit includes at least a flash tank, the flash tank being provided with at least a material inlet, a defoliated polymer outlet, and a volatile matter outlet.

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

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

[0088] In the continuous solution polymerization system described above, preferably, the polymerization reaction raw material inlet of the polymerization reactor is located at the bottom of the polymerization reactor, and the polymer solution outlet is located at the top of the polymerization reactor. In some specific embodiments of the present invention, the polymerization reaction raw material inlet of the polymerization reactor includes an olefin monomer and solvent inlet, as well as a catalyst system and a selectively installed cleaning agent inlet. Specifically, the main catalyst, co-catalyst and cleaning agent in the metallocene catalyst system are each transported by material transport branch lines, and the three material transport branch lines merge into a main material transport pipe before connecting to the catalyst system and cleaning agent inlet of the polymerization reactor. Preferably, the three material transport branch lines merge into a main material transport pipe before connecting to the catalyst system and cleaning agent inlet of the polymerization reactor via a loop tube reactor, which is used to enhance mixing and activate the main catalyst, co-catalyst and cleaning agent in the metallocene catalyst system.

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

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

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

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

[0093] According to a specific embodiment of the present invention, preferably, the continuous solution polymerization system includes a raw material preparation unit comprising at least an ethylene buffer tank, an ethylene dissolution tank, and a comonomer storage tank, wherein the ethylene buffer tank may be provided with a fresh ethylene inlet, an optional circulating ethylene inlet, and an ethylene outlet; the ethylene dissolution tank may be provided with a solvent inlet, an ethylene inlet, and an ethylene-solvent mixture outlet; the comonomer storage tank may be provided with a solvent inlet, a comonomer inlet, and a comonomer-solvent mixture outlet; the ethylene outlet of the ethylene buffer tank is connected to the ethylene inlet of the ethylene dissolution tank via a line; material transport branch lines are provided at the ethylene-solvent mixture outlet of the ethylene dissolution tank and the comonomer-solvent mixture outlet of the comonomer storage tank, respectively; the two material transport branch lines merge into a main material transport pipe and then connect to the olefin monomer and solvent inlets of the polymerization reactor. More preferably, a preheater is provided in the main material transport pipe.

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

[0095] In the above-described continuous solution polymerization system, preferably, the polymer solution inlet of the termination / complexing equipment is located at the bottom of the termination / complexing equipment, the complexing agent inlet is located at the bottom of the termination / complexing equipment, and the mixed liquid outlet is located at the top of the termination / complexing equipment.

[0096] In the continuous solution polymerization system described above, preferably, the demetallation unit further includes a complexing agent storage tank, the complexing agent storage tank being connected via a line to the complexing agent inlet of the termination / complexing equipment.

[0097] In the above-described continuous solution polymerization system, preferably, a centrifuge is provided on the line connecting the mixed liquid outlet of the termination / complexing equipment and the oil phase inlet of the washing tank. More preferably, a heat exchanger is installed on the line connecting the centrifuge and the oil phase inlet of the washing tank to bring the oil phase to the washing operating temperature.

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

[0099] In the continuous solution polymerization system described above, the number of washing tanks is preferably 1 to 5. When multiple washing tanks are used, they are installed in series. A centrifuge is installed in the line connected to the polymer solution outlet of each washing tank to separate the oil and water from the washed solution to obtain the oil phase. A heat exchanger is then installed after each centrifuge to bring the oil phase to the washing operating temperature.

[0100] In the above-described 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 defoliation is provided at the bottom of the flash tank, and the volatile matter outlet is provided at the top of the flash tank.

[0101] In the continuous solution polymerization system described above, preferably, the number of flash tanks is one or more, and if two or more flash tanks are used, the two or more flash tanks are arranged in series. More preferably, each flash tank is equipped with one heat exchanger to provide the amount of heat required for the defolatorial process, and the heat exchanger is installed in a line connected to the material inlet of the flash tank, and a transfer pump is installed in a line connected to the defolatorial polymer outlet of each flash tank to transport the defolatorial polymer. Specifically, the transfer pump may include a gear pump or a screw pump, etc.

[0102] In the continuous solution polymerization system described above, preferably, a degassing port is provided at the extrusion end of the extrusion granulator. More preferably, there are two degassing openings, one located in the middle and the other at 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 continuous solution polymerization system described above, the extruder preferably includes a twin-screw extruder. More preferably, the aspect ratio of the extruder screw of the twin-screw extruder is 40 to 80:1, and even more preferably 45 to 65:1.

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

[0105] In a specific embodiment of the present invention, preferably, the continuous solution polymerization system further comprises a rectification unit including at least a rectification column and a reflux tank, wherein the rectification column is provided with a volatile matter inlet, an ethylene outlet, an unreacted comonomer outlet, and a solvent outlet, the volatile matter inlet of the rectification column is connected to the volatile matter outlet of the flash tank via a line, the ethylene outlet of the rectification column is in communication with the reflux tank, a reflux line is installed in the reflux tank, the reflux line is connected to the rectification column, and the gas-liquid separated liquid phase in the reflux tank is returned to the rectification column for further rectification. Specifically, the volatile matter inlet of the rectification column may be installed on the side wall of the rectification column, the ethylene outlet may be installed at the top of the rectification column, the unreacted comonomer outlet may be 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 is connected to the volatile matter inlet of the rectification column via a line. Specifically, the degassing port at the extrusion end of the extrusion granulator is connected to the volatile matter 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 comprising at least a compressor, the inlet of the compressor being connected via a line to the reflux tank, and the outlet of the compressor being connected via a line to the circulating ethylene inlet of the ethylene buffer tank.

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

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

[0110] In this field, during the process of producing polyolefins using metallocene catalysts and solution polymerization, the residual content of catalyst metals in the polymer solution obtained after the polymerization reaction is usually high. If the removal of residual metals is insufficient, it can cause discoloration of the polyolefin product and deteriorate its performance, such as heat resistance and durability.

[0111] In demetallation, the present invention employs dicarboxylic acids and their derivatives having a cis structure in their spatial arrangement as metal complexing agents. These cis-structured dicarboxylic acids and their derivatives form a cyclic transition state with metal ions in the polymer solution, further forming a water-soluble metal complex with a stable cyclic structure. Subsequently, the water-soluble metal complex is removed by washing with water to obtain a demetallated polymer solution. Therefore, the present invention can efficiently remove metal ions remaining in the polymer solution, significantly reducing residual metals in polymer products, particularly polyolefin products. Compared to conventional polymer demetallation technologies, the present invention has advantages such as high demetallation efficiency, high speed, simple process, low cost, and the ability to operate continuously for long periods. It can be widely applied in the field of polymer metal removal, possesses versatility and efficiency, and has broad potential for industrialization.

[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 dicarboxylic acids and their derivatives having a cis structure in spatial arrangement as metal complexing agents, which promote the formation of metal complexes by forming a cyclic transition state with metal ions, thereby forming stable water-soluble metal complexes. This has the advantage of efficiently complexing and removing metals, and significantly improves the metal removal rate from polymer solutions.

[0114] 2. The present invention has advantages such as being easy to operate and low cost because it removes metal complexes by washing with water.

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

[0116] As described above, the present invention provides a continuous solution polymerization method and system, and in particular, a method and system for producing polyolefins by continuous solution polymerization using a metallocene catalyst. The method and system of the present invention can deeply and efficiently remove residual metal from the catalyst in the polymer, and 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. Polymer products produced by the method and system of the present invention can meet the requirements of medical-grade and optical-grade polymer materials. Furthermore, the method and system of the present invention has advantages such as a short process, low production cost, and the ability to operate continuously for long periods. [Brief explanation of the drawing]

[0117] [Figure 1] This is a schematic diagram of a continuous solution polymerization system according to a specific embodiment of the present invention. [Explanation of symbols]

[0118] 1: Ethylene buffer tank 2: Ethylene dissolution tank 3: Comonomer storage tank 4: Polymerization reactor 5: Termination / complexing equipment 6: Complexing agent storage tank 7: Washing tank 8: First centrifuge 9: Second centrifuge 10: Flash tank 11: Gear pump 12: Rectification column 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. [Modes for carrying out the invention]

[0119] To provide a clearer understanding of the technical features, objectives, and beneficial effects of the present invention, the proposed technical aspects of the invention will be described in detail below, but this should not be understood as limiting the scope of the invention's applicability.

[0120] Example 1 As shown in Figure 1, this embodiment provides a continuous solution polymerization system including a raw material preparation unit, a polymerization reaction unit, a demetallation unit, a defoliation 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 recirculated ethylene inlet, and an ethylene outlet. The ethylene dissolution tank 2 is provided with a solvent inlet, an ethylene inlet, and an outlet for a mixture of ethylene and solvent. The comonomer storage tank 3 is provided with a solvent inlet, a comonomer inlet, and an outlet for a mixture of comonomer and solvent.

[0122] The polymerization reaction unit includes at least a polymerization reactor 4, the polymerization reactor 4 being provided with an inlet for olefin monomers and solvent, an inlet for a catalyst system and cleaning agent, and an outlet for a polymer solution.

[0123] The demetallation unit includes at least a termination / complexing equipment 5, a complexing agent storage tank 6, a washing tank 7, a first centrifuge 8, and a second centrifuge 9. The termination / complexing equipment 5 is equipped with a polymer solution inlet, a complexing agent inlet, and a mixed liquid outlet, and the washing tank 7 is equipped with an oil phase inlet, a deionized water inlet, and a polymer solution outlet.

[0124] The defoliation unit includes at least a flash tank 10, the flash tank 10 being provided with a material inlet, a polymer outlet after defoliation, 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 being 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 Figure 1), and a solvent circulation line (not shown in Figure 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 transport branch lines are installed at the outlet of the ethylene-solvent mixture of the ethylene dissolution tank 2 and at the outlet of the comonomer-solvent mixture of the comonomer storage tank 3, respectively. The two material transport branch lines merge into a main material transport pipe and are then connected to the olefin monomer and solvent inlet of the polymerization reactor 4. Each of the two material transport branch lines is also provided with a metering pump (not shown in Figure 1), and a preheater 16 is provided in the main material transport pipe.

[0129] In the metallocene catalyst system, the main catalyst, co-catalyst, and cleaning agent are each transported by material transport branch lines. The three material transport branch lines merge into the main material transport pipe and are then connected to the catalyst system and cleaning agent inlet of the polymerization reactor 4 via the loop tube reactor 21. Each of the three material transport branch lines is also equipped with a syringe pump (not shown in Figure 1). The loop tube reactor 21 is used to enhance mixing and activate the main catalyst, co-catalyst, and cleaning agent in the metallocene catalyst system.

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

[0131] The polymerization reactor 4 is equipped with a stirrer, such as a paddle mixer. The polymerization reactor 4 is also equipped with an external jacket, and the polymerization reaction temperature can be controlled by the external jacket of the polymerization reactor 4 using a high-temperature oil bath system. The polymerization reactor 4 does not have a cooling coil, which prevents the polymer from adhering to the tube walls of a cooling coil.

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

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

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

[0135] The polymer solution outlet of the 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 washing tanks 7 is 1 to 5 (Figure 1 does not show multiple washing tanks). When multiple washing tanks are used, they are installed in series. A centrifuge is installed in the line connected to the polymer solution outlet of each washing tank to separate the oil and water from the washed solution to obtain the oil phase. A heat exchanger is then installed after each centrifuge to bring the oil phase to the washing operating temperature.

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

[0138] A degassing port 131 is provided at the extrusion end of the extrusion granulator 13. There are two degassing ports 131, one located in the middle and the other at 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 ports 131. The vacuum degassing device 132 includes, but is not limited to, a vacuum pump.

[0139] In this embodiment, the extruder granulator 13 is a twin-screw extruder granulator. The aspect ratio of the extruder screw of the twin-screw extruder 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 is connected to the volatile matter inlet of the rectification column 12 via the line and the vacuum degassing device 132.

[0142] The ethylene outlet of the rectification column 12 is connected to the reflux tank 14, and the reflux tank 14 is provided with a reflux line connected to the rectification column 12 for returning the liquid phase separated 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 connecting the outlet of the unreacted comonomer of the rectification column 12 with the comonomer inlet of the comonomer storage tank 3.

[0145] The solvent circulation line is for connecting 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 2-7 Examples 2 to 7 each provide a continuous solution polymerization method, and all of them employ the continuous solution polymerization system provided in Example 1.

[0147] The continuous solution polymerization method described in Examples 2 to 7 includes the following steps.

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

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

[0150] Step (2): In the polymerization reaction unit, the mixture of olefin monomer and solvent obtained in Step (1) is introduced into the polymerization reaction tank 4 from the bottom. At the same time, the main catalyst, co-catalyst, and cleaning agent of the metallocene catalyst system are transported by syringe pump and material transport branch line, respectively, and combined. After enhanced mixing and activation in the loop tube reactor 21, the mixture is introduced into the polymerization reaction tank 4 from the bottom, and the polymerization reaction is carried out in the polymerization reaction tank 4. The temperature, pressure, and time of the polymerization reaction (i.e., 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 employs a full-clave operation. The polymer solution obtained after the reaction flows out from the top of the polymerization reaction tank 4. The pressure of the polymerization reaction can be controlled by the pressure control valve 20, and at the same time, the temperature of the polymerization reaction can be controlled by the jacket of the polymerization reaction tank 4 using a high-temperature oil bath system.

[0151] Here, the main catalyst is a zirconium-containing metallocene compound, the co-catalyst is an alkylaluminoxane, and the cleaning agent is triisobutylaluminum and / or triethylaluminum, and the amounts used for each of these may be normally adjusted by those skilled in the art.

[0152] Step (3): In the demetallation unit, the polymer solution obtained in step (2) is cooled by the first heat exchanger 17, then the pressure is reduced by the pressure control valve 20, and then it enters the termination / complexing equipment 5, where the polymer solution is cooled and the temperature and pressure after depressurization are as shown in Table 1. The complexing agent solution in the complexing agent storage tank 6 is then injected into the termination / complexing equipment 5 according to the calculated amount to terminate the polymerization reaction and simultaneously form the metal ions in the polymer solution into water-soluble metal complexes, obtaining a mixed solution. The mixed solution is separated into oil and water using the first centrifuge 8, the obtained oil phase is heat-exchanged using the second heat exchanger 18, then it is placed in the washing tank 7 and washed with water, and the washed polymer solution is separated into oil and water using the second centrifuge 9, and the obtained oil phase is the demetallation polymer solution. Here, there is one or more washing tanks 7, the number of washings is 1 to 5, and the specific number of washings, washing temperature and water-oil volume are as shown in Table 1.

[0153] Step (4): In the defoliation unit, the demetallated polymer solution obtained in step (3) is subjected to heat exchange in the third heat exchanger 19, then placed in the flash tank 10, where the demetallated polymer solution is flash-separated. The temperature of the demetallated polymer solution after heat exchange, the flash temperature, and the pressure are as shown in Table 1, to obtain the defoliated polymer and volatile matter. The defoliated polymer flows out from the bottom of the flash tank 10, and the volatile matter flows out from the top of the flash tank 10. The volatile matter content in the defoliated polymer is 5% or less (by weight percentage), and the weight percentage content of unreacted comonomers in the volatile matter is as shown in Table 1.

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

[0155] Step (6): In the rectification unit, the volatile matter discharged from the top of the flash tank 10 obtained in step (4) and the volatile matter removed by the extruder granulator 13 in step (5) are placed in the rectification column 12 and rectified. The operating conditions of the rectification column 12 are as shown in Table 1. The ethylene discharged from the top of the rectification column 12 enters the reflux tank 14, where it is exhausted and gas-liquid separated to obtain ethylene, as well as unreacted comonomer discharged from the side wall of the rectification column 12 and solvent discharged from the bottom of the rectification column 12. After gas-liquid separation in the reflux tank, the resulting liquid phase is returned to the rectification column and rectification is repeated.

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

[0157] [Table 1-1] [Table 1-2] The demetallation step in the continuous solution polymerization method provided in Examples 2 to 7 is specifically as follows:

[0158] Example 2 In the demetallation unit, the polymer solution obtained in step (2) is cooled by the first heat exchanger 17, then the pressure is reduced by the pressure control valve 20, and then it enters the termination and complexing equipment 5. Under vigorous 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 complexing equipment 5. The injection amount is 2.5% of the volume of the polymer solution in the termination and complexing equipment 5, and the residence time is 5 minutes. At the same time as terminating the polymerization reaction, the metal ions in the polymer solution are formed into water-soluble metal complexes, and a mixed solution is obtained. The mixed solution is separated into oil and water using the first centrifuge 8, and the resulting oil phase is heat-exchanged using the second heat exchanger 18. After that, it is placed in the washing tank 7 and washed with water. The polymer solution after washing is separated into oil and water using the second centrifuge 9, and then the heat exchange, washing, and oil-water separation operations are repeated. After washing with water three times, the resulting oil phase was the demetallated polymer solution.

[0159] Example 3 In the demetallation unit, the polymer solution obtained in step (2) is cooled by the first heat exchanger 17, then the pressure is reduced by the pressure control valve 20, and then it enters the termination and complexing equipment 5. Under vigorous stirring conditions, a maleic anhydride ethanol solution with a concentration of 0.5 mol / L in the complexing agent storage tank 6 is continuously injected into the termination and complexing equipment 5. The injection amount is 3% of the volume of the polymer solution in the termination and complexing equipment 5, and the residence time is 10 minutes. At the same time as terminating the polymerization reaction, the metal ions in the polymer solution are formed into water-soluble metal complexes, and a mixture is obtained. The mixture is separated into oil and water using the first centrifuge 8, the obtained oil phase is heat-exchanged using the second heat exchanger 18, then it is placed in the washing tank 7 and washed with water, the washed polymer solution is separated into oil and water using the second centrifuge 9, and then the heat exchange, washing and oil-water separation operations are repeated. After two washes with water, the obtained oil phase was the demetallated polymer solution.

[0160] Example 4 In the demetallation unit, the polymer solution obtained in step (2) is cooled by the first heat exchanger 17, then the pressure is reduced by the pressure control valve 20, and then it enters the termination and complexing equipment 5. Under vigorous stirring conditions, a cis-butenediate acetone solution with a concentration of 1 mol / L in the complexing agent storage tank 6 is continuously injected into the termination and complexing equipment 5. The injection amount is 1% of the volume of the polymer solution in the termination and complexing equipment 5, and the residence time is 20 minutes. At the same time as terminating the polymerization reaction, the metal ions in the polymer solution are formed into water-soluble metal complexes, and a mixture is obtained. The mixture is separated into oil and water using the first centrifuge 8, the obtained oil phase is heat-exchanged using the second heat exchanger 18, then it is placed in the washing tank 7 and washed with water. The washed polymer solution is separated into oil and water using the second centrifuge 9, and then the heat exchange, washing, and oil-water separation operations are repeated four times. The obtained oil phase was the demetallated polymer solution.

[0161] Example 5 In the demetallation unit, the polymer solution obtained in step (2) was cooled by the first heat exchanger 17, then the pressure was reduced by the pressure control valve 20, and then it entered the termination and complexing equipment 5. Under vigorous stirring conditions, an aqueous solution of 2,3-dimethylmaleic acid anhydride with a concentration of 2 mol / L in the complexing agent storage tank 6 was continuously injected into the termination and complexing equipment 5. The injection amount was 1.5% of the volume of the polymer solution in the termination and complexing equipment 5, and the residence time was 30 minutes. At the same time as stopping the polymerization reaction, the metal ions in the polymer solution were formed into water-soluble metal complexes, and a mixed solution was obtained. The mixed solution was separated into oil and water using the first centrifuge 8, and the resulting oil phase was subjected to heat exchange in the second heat exchanger 18. After that, it was placed in the washing tank 7 and washed with water. The polymer solution after washing was separated into oil and water using the second centrifuge 9, and the resulting oil phase was the demetallated polymer solution.

[0162] Example 6 In the demetallation unit, the polymer solution obtained in step (2) was cooled in the first heat exchanger 17, then the pressure was reduced by the pressure control valve 20, and then it entered the termination and complexing equipment 5. Under vigorous stirring conditions, a 2,3-dimethylmaleic acid anhydride ethanol solution with a concentration of 3 mol / L in the complexing agent storage tank 6 was continuously injected into the termination and complexing equipment 5. The injection amount was 1% of the volume of the polymer solution in the termination and complexing equipment 5, and the residence time was 40 minutes. At the same time as stopping the polymerization reaction, the metal ions in the polymer solution were formed into water-soluble metal complexes, and a mixture was obtained. The mixture was separated into oil and water using the first centrifuge 8, and the resulting oil phase was heat-exchanged in the second heat exchanger 18. After that, it was placed in the washing tank 7 and washed with water. The washed polymer solution was separated into oil and water using the second centrifuge 9, and then the heat exchange, washing, and oil-water separation operations were repeated five times. The resulting oil phase was the demetallated polymer solution.

[0163] Example 7 In the demetallation unit, the polymer solution obtained in step (2) was cooled in the first heat exchanger 17, then the pressure was reduced by the pressure control valve 20, and then it entered the termination and complexing equipment 5. Under vigorous stirring conditions, a 2,3-dimethylmaleic anhydride acetone solution with a concentration of 5 mol / L in the complexing agent storage tank 6 was continuously injected into the termination and complexing equipment 5. The injection amount was 5% of the volume of the polymer solution in the termination and complexing equipment 5, and the residence time was 60 minutes. At the same time as stopping the polymerization reaction, the metal ions in the polymer solution were formed into water-soluble metal complexes, and a mixture was obtained. The mixture was separated into oil and water using the first centrifuge 8, and the resulting oil phase was heat-exchanged in the second heat exchanger 18. After that, it was placed in the washing tank 7 and washed with water. The washed polymer solution was separated into oil and water using the second centrifuge 9, and then the heat exchange, washing, and oil-water separation operations were repeated. After washing with water three times, the resulting oil phase was the demetallated polymer solution.

[0164] Comparative Example 1 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 demetallation step.

[0165] The demetallation step in this comparative example was as follows.

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

[0167] Comparative Example 2 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 demetallation step.

[0168] The demetallation step in this comparative example was as follows.

[0169] In the demetallation unit, the polymer solution obtained in step (2) is cooled by the first heat exchanger 17, then the pressure is reduced by the pressure control valve 20, and then it enters the termination and complexing equipment 5. Under vigorous 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 complexing equipment 5. The injection amount is 2.5% of the volume of the polymer solution in the termination and complexing equipment 5, and the residence time is 5 minutes. At the same time as terminating the polymerization reaction, the metal ions in the polymer solution are formed into water-soluble metal complexes, and a mixed solution is obtained. The mixed solution is separated into oil and water using the first centrifuge 8, the obtained oil phase is heat-exchanged using the second heat exchanger 18, then it is washed with water in the washing tank 7, the washed polymer solution is separated into oil and water using the second centrifuge 9, and then the heat exchange, washing, and oil-water separation operations are repeated three times. The obtained oil phase was the demetallated polymer solution.

[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 demetallation step. The demetallation unit in this comparative example does not have components such as the termination and complexing equipment 5, the complexing agent storage tank 6, and the washing tank 7. The polymer solution is cooled and depressurized, and then adsorbed and separated by an adsorption column packed with an adsorbent.

[0171] The demetallation step in this comparative example was as follows.

[0172] 250 mL of powdered aluminum trioxide (the same as the powdered aluminum trioxide in Example 2) was taken, heated to 100°C, and then 100 mL of a 0.005 mol / L maleic acid aqueous solution was added. The mixture was then stirred for 2 hours, filtered, and the filtration residue was removed. The mixture was dried 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 was 0.41 g / mL, and the specific surface area was 212 m². 2 The pore volume was 0.42 mL / g.

[0173] In the demetallation unit, the polymer solution obtained in step (2) is cooled and depressurized, and then subjected to a temperature and pressure of 50°C and 0.2 MPa for 0.5 hours. -1 At a volume-space velocity, the aluminum trioxide powder pretreated with maleic acid is adsorbed and separated using an adsorption column, and a demetallated polymer solution is obtained.

[0174] Comparative Example 4 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 demetallation step.

[0175] The demetallation step in this comparative example was as follows.

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

[0177] Test Example 1 Table 2 shows the results of detecting the metal content and VOC content in the polymer particles prepared in Examples 2-7 and Comparative Examples 1-4. The polymer solutions obtained in step (2) in Examples 2-7 and Comparative Examples 1-4 were not treated in the demetallation unit in step (3), but were instead treated directly in the subsequent defoliation unit and extrusion granulation unit to obtain polymer particles, and the results of detecting the metal content therein are shown in Table 2.

[0178] Here, the metal content in polymer particles was measured using an incineration method, and the specific steps involved were standard technical methods in this art. Specifically, the incineration method used in this test example involved placing 100 g of polymer particles into a muffle furnace, raising the temperature to 650°C in 1 hour using a programmed heating method, then keeping the temperature constant for 2 hours to allow the polymer to burn completely, then cooling to room temperature, adding the remaining ash after incineration to 5 mL of hydrochloric acid solution (the mass fraction of the hydrochloric acid solution is 19%), and after the ash was completely dissolved, analyzing the metal content in the solution by ICP-MS.

[0179] The VOC content in polymer particles was measured using the oven method, and the specific steps involved were those of a standard technical procedure in this field. The operating conditions of the oven method used in this test included 100°C and vacuum drying.

[0180] [Table 2] As can be seen from Table 2, the continuous solution polymerization method and system of the present invention can efficiently remove metal ions remaining in the polymer solution, significantly reduce the residual metal in the polymer product, and produce polymer products with high transparency, low metal content, and low VOC content. The present invention has the following embodiments <1> ~ <25> Includes. <1> Step (1): Polymerize the raw materials for the polymerization reaction to obtain a polymer solution. Step (2): After mixing the polymer solution with the complexing agent and allowing it to react, a mixture is obtained, and the mixture is washed with water to obtain the demetallated polymer solution. Step (3): After demetallation of the polymer solution, obtain the devolatile polymer and volatile components. Step (4): After the defoliated polymer is extruded and granulated, polymer particles are obtained. A continuous solution polymerization method comprising, A continuous solution polymerization method wherein the complexing agent comprises one or more dicarboxylic acids and their derivatives, the dicarboxylic acid comprising a carbon-carbon double bond and having two carboxyl groups arranged on the same side of the carbon-carbon double bond, and having a cis structure in spatial arrangement. <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 further selectively contain a cleaning agent. The olefin monomer includes one or more combinations of ethylene, α-olefins, and cycloolefins. The solvent comprises one or more combinations of C6-C12 alkanes, cycloalkanes, and aromatic hydrocarbons. The catalyst system includes a metallocene catalyst system. <1> The continuous solution polymerization method described above. <3> In step (1), the temperature of the polymerization reaction is 70 to 180°C, the pressure of the polymerization reaction is 0.5 to 1.5 MPa, and the time of the polymerization reaction is 30 to 120 min. <1> The continuous solution polymerization method described above. <4> Prior to step (1), the process further includes a raw material preparation step relating to an olefin monomer and a solvent, the raw material preparation step comprising mixing the olefin monomer and the solvent and preheating, <2> The continuous solution polymerization method described above. <5> The aforementioned raw material preparation step is: To obtain a mixture of ethylene and solvent by mixing ethylene with a solvent in a way that dissolves it, To obtain a mixture of comonomer and solvent by mixing the comonomer with a solvent in such a way that it dissolves. After mixing a mixture of ethylene and a solvent with a mixture of comonomer and a solvent and preheating, a mixture of olefin monomer and a solvent is obtained. Includes, The dissolution temperature of ethylene is 20-90°C, and the pressure is 0.1-5.0 MPa. The temperature at which the comonomer and solvent are mixed is 25-75°C, and the pressure is 0.05-0.2 MPa. The temperature of the mixture of olefin monomer and solvent obtained after mixing and preheating is 60-160°C. <4> The continuous solution polymerization method described above. <6> In step (2), the dicarboxylic acid has a structure represented by the following formula I. <1> The continuous solution polymerization method described above.

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Claims

1. Step (1): Polymerize the raw materials for the polymerization reaction to obtain a polymer solution. Step (2): After mixing the polymer solution with the complexing agent and allowing it to react, a mixture is obtained, and the mixture is washed with water to obtain the demetallated polymer solution. Step (3): After demetallation of the polymer solution, obtain the devolatile polymer and volatile components. Step (4): After extruding the defoliated polymer, polymer particles are obtained. A continuous solution polymerization method comprising, The raw materials for the polymerization reaction include an olefin monomer, a solvent, and a catalyst system. The raw materials for the polymerization reaction further selectively contain a cleaning agent. The olefin monomer includes one or more combinations of ethylene, α-olefins, and cycloolefins. The solvent comprises one or more combinations of C6-C12 alkanes, cycloalkanes, and aromatic hydrocarbons. The catalyst system includes a metallocene catalyst system. A continuous solution polymerization method wherein the complexing agent comprises one or more dicarboxylic acids and their derivatives, the dicarboxylic acid comprises a carbon-carbon double bond, and two carboxyl groups are arranged on the same side of the carbon-carbon double bond, resulting in a cis structure in spatial arrangement.

2. The continuous solution polymerization method according to claim 1, wherein in step (1), the temperature of the polymerization reaction is 70 to 180°C, the pressure of the polymerization reaction is 0.5 to 1.5 MPa, and the time of the polymerization reaction is 30 to 120 min.

3. The continuous solution polymerization method according to claim 1, further comprising a raw material preparation step relating to an olefin monomer and a solvent prior to step (1), wherein the raw material preparation step comprises mixing the olefin monomer and the solvent and preheating.

4. The aforementioned raw material preparation step is: To obtain a mixture of ethylene and solvent by mixing ethylene with a solvent in a way that dissolves it, To obtain a mixture of comonomer and solvent by mixing the comonomer with a solvent in such a way that it dissolves. After mixing a mixture of ethylene and a solvent with a mixture of comonomer and a solvent and preheating, a mixture of olefin monomer and a solvent is obtained. Includes, The temperature at which ethylene dissolves is 20 to 90°C, and the pressure is 0.1 to 5.0 MPa. The temperature at which the comonomer and solvent are mixed is 25 to 75°C, and the pressure is 0.05 to 0.2 MPa. The temperature of the mixture of olefin monomer and solvent obtained after mixing and preheating is 60 to 160°C. The continuous solution polymerization method according to claim 3.

5. 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. 【Chemistry 1】 (In formula I, R １ , R ２ They are either the same or different, and R １ and R ２ Each of these is independently selected from an H atom and a C1-C10 linear or branched alkyl group.

6. The continuous solution polymerization method according to claim 1, wherein in step (2), the derivative of the dicarboxylic acid includes one or more combinations of acid anhydrides, acid halides, amides, esters, and nitriles formed from the dicarboxylic acid.

7. The continuous solution polymerization method according to claim 6, 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. 【Chemistry 2】 (In formula II, R １ , R ２ They are either the same or different, and R １ and R ２ Each of these is independently selected from an H atom and a C1-C10 linear or branched alkyl group.

8. 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.

9. 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 more combinations of water, alcohols, ketones, and hydrocarbons. The continuous solution polymerization method according to claim 1.

10. In step (2), the temperature at which the polymer solution and the complexing agent are mixed and reacted 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.

11. Step (2) specifically is: After heat exchange and reduced pressure of the polymer solution, it is placed in a termination and complexing facility, and a complexing agent is injected into the termination and complexing facility to terminate the polymerization reaction. At the same time, the metal ions in the polymer solution are formed into water-soluble metal complexes, and a mixed solution is obtained. After separating the oil and water from the aforementioned mixture, the resulting oil phase is subjected to heat exchange, washed with water, and then separated again with oil and water. The resulting oil phase is the polymer solution after demetallation. including, The continuous solution polymerization method according to claim 1.

12. The continuous solution polymerization method according to claim 11, wherein the temperature of the water wash is 30 to 60°C, and the volume ratio of the amount of water used for the water wash to the oil phase is 1 to 20:

1.

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

14. In step (4), the equipment for extruding and granulating the defoliated polymer includes an extruder, a degassing port is installed at the extrusion end of the extruder, and after extrusion, volatile components in the defoliated polymer are further removed, and the polymer is further granulated by passing through the granulation end of the extruder to obtain 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.

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

16. The continuous solution polymerization method according to claim 15, further comprising step (5) being to place the volatile matter obtained in step (3) and the volatile matter removed by extrusion granulation in step (4) into a rectification column and perform rectification, the ethylene discharged from the top of the rectification column into a reflux tank where it is exhausted and gas-liquid separated to obtain ethylene, as well as unreacted comonomers discharged from the side walls of the rectification column and solvent discharged from the bottom of the rectification column, and returning the liquid phase obtained after gas-liquid separation in the reflux tank to the rectification column and performing rectification again.

17. Step (6): The continuous solution polymerization method according to claim 16, further comprising recycling one or more of the ethylene obtained in step (5), the unreacted comonomer, and the solvent.

18. A continuous solution polymerization system for realizing the continuous solution polymerization method described in claim 1, comprising at least a polymerization reaction unit, a demetallation unit, a defoliation unit, and an extrusion granulation unit, The polymerization reaction unit includes at least a polymerization reaction vessel, and the polymerization reaction vessel is provided with at least a polymerization reaction raw material inlet and a polymer solution outlet. The demetallation unit includes at least a termination / complexing facility and a washing tank, the termination / complexing facility is provided with at least a polymer solution inlet, a complexing agent inlet, and a mixed liquid outlet, and the washing tank is provided with an oil phase inlet, a water inlet, and a polymer solution outlet. The defoliation unit includes at least a flash tank, the flash tank is provided with at least a material inlet, a defoliated polymer outlet, and a volatile matter outlet. The extrusion granulation unit includes at least an extrusion granulator, A continuous solution polymerization system wherein the polymer solution outlet of the polymerization reactor is connected via a line to the polymer solution inlet of the termination and complexing equipment, the mixed liquid outlet of the termination and complexing equipment is connected via a line to the oil phase inlet of the washing tank, the polymer solution outlet of the washing tank is connected via a line to the material inlet of the flash tank, and the defoliated polymer outlet of the flash tank is connected via a line to the extrusion granulator.

19. The polymerization reaction raw material inlet of the polymerization reaction vessel is located at the bottom of the polymerization reaction vessel, and the polymer solution outlet is located at the top of the polymerization reaction vessel. The polymerization reaction raw material inlet of the polymerization reactor includes an olefin monomer and solvent inlet, as well as a catalyst system and a selectively provided cleaning agent inlet. A heat exchanger and a pressure control valve are installed in the line connecting the polymer solution outlet of the polymerization reactor and the polymer solution inlet of the termination / complexing equipment. The continuous solution polymerization system according to claim 18.

20. The polymer solution inlet of the termination and complexing equipment is located at the bottom of the termination and complexing equipment, the complexing agent inlet is located at the bottom of the termination and complexing equipment, and the mixed liquid outlet is located at the top of the termination and complexing equipment. The demetallation unit further includes a complexing agent storage tank, which is connected via a line to the complexing agent inlet of the termination and complexing equipment. A centrifugal separator is installed in the line connecting the mixed liquid outlet of the aforementioned termination and complexing equipment and the oil phase inlet of the aforementioned washing tank. A centrifuge is installed in the line connecting the polymer solution outlet of the washing tank and the material inlet of the flash tank. The continuous solution polymerization system according to claim 18.

21. The material inlet of the flash tank is installed on the side wall of the flash tank, the polymer outlet after defoliation is installed at the bottom of the flash tank, and the volatile matter outlet is installed at the top of the flash tank. The number of the aforementioned flash tanks may be one or two or more, and when two or more flash tanks are used, the two or more flash tanks are arranged in series. Each flash tank is equipped with a heat exchanger to provide the heat required for the defoliation process, and the heat exchanger is installed in a line connected to the material inlet of the flash tank. Furthermore, to transport the polymer after defolamination, a transport pump is installed in each line connected to the polymer outlet of each flash tank after defolamination. The continuous solution polymerization system according to claim 18.

22. A degassing port is provided at the extrusion end of the extrusion granulator. The number of the aforementioned degassing ports is two, and they are installed in the middle and end sections of the extrusion end of the extrusion granulator, respectively. The continuous solution polymerization system according to claim 18.

23. The continuous solution polymerization system according to claim 22, wherein 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.

24. The continuous solution polymerization system according to claim 18, wherein the extrusion granulator includes a twin-screw extrusion granulator, and the aspect ratio of the extrusion screws of the twin-screw extrusion granulator is 40 to 80:1.

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