Continuous olefin polymerization process in the presence of antistatic agents.

Abstract

A method for continuously producing a polyolefin polymer in a gas-phase polymerization reactor in the presence of a polymerization catalyst and an antistatic agent, the method comprising the steps of: supplying a mixture of polyolefin particles and a gas; and conveying the mixture through a pipe at a gas velocity of 2 m / s or more; and introducing the antistatic agent into the mixture.

Description

[Technical Field]

[0001] The present disclosure relates to a process for continuously producing polyolefin polymers in a gas phase polymerization reactor in the presence of a polymerization catalyst and an antistatic agent, and an apparatus for carrying out said process. [Background technology]

[0002] During polymer production, high levels of static electricity tend to cause polymer particles to adhere to the reactor walls, which not only risks the formation of lumps and wall sheets, which in most cases lead to an unavoidable shutdown of the polymerization reactor due to clogging, but also disturbs the fluid dynamics within the reactor and prevents the fluidization of the polymer particles.

[0003] Therefore, antistatic agents are used in olefin polymerization processes to prevent static charging and reduce wall sheeting and polymer agglomeration in polymerization reactors or downstream equipment such as degassing vessels and recovery vessels. In the context of polyolefin polymerization, antistatic agents are also referred to as antifouling agents, polymerization process aids, activity inhibitors, or kinetic modifiers. Antistatic agents consist of antistatic compounds with polar functional groups, such as acid or ester groups, amine or amide groups, or hydroxyl or ether groups. Common examples of antistatic compounds include polysulfone copolymers, polymeric polyamines, polyalcohols, hydroxy esters of polyalcohols, salts of alkylarylsulfonic acids, polysiloxanes, alkoxyamines, and polyglycol ethers.

[0004] U.S. Patent No. 5,410,002 describes a polymerization process in which an antistatic compound is used to remove or reduce the buildup of polymer particles on the walls of a gas-phase polymerization reactor. The compound is believed to selectively inhibit the polymerization of polymer particles smaller than 850 μm, which have been identified as the cause of fouling problems and polymer sheeting.

[0005] In a multi-zone circulating reactor, for example, polymer particles can adhere to the riser walls, causing a continuous buildup of coating on the riser walls. When these agglomerated polymer particles fall at a certain point, the amount of transportable polymer particles in the riser increases dramatically, transporting more polymer to the downcomer, and causing the polymer particle level in the downcomer to rise very quickly. However, as the number of polymer particles in the riser increases, not only does the density of the reactor contents in the riser temporarily change, but the hydrodynamics of the reaction mixture also fluctuate. Furthermore, changes in the polymer particle level in the downcomer also affect the hydrodynamics of the entire multi-zone circulating reactor. While several antistatic agents are known to those skilled in the art to address this issue, they are only effective if properly dispersed on the polymer powder.

[0006] WO 2017 / 108337 discloses a process for preparing polyolefins, which comprises: a) 0.5 to 50% by weight of a compound of the formula R-OH, where R represents hydrogen or a linear or branched saturated alkyl group having 1 to 15 carbon atoms; and b) a polyolefin having one or more terminal hydroxyl groups and having a viscosity at 40°C of at least 20 mmHg. 2 The method comprises polymerizing olefins in the presence of an antistatic compound containing 50 to 99% by weight of an oligomeric or polymeric organic compound having a solubility in water of 1000 to 1500 sq ft (DIN 51562). The antistatic compound may be introduced into the reactor at various locations, such as directly into the reactor, in a line leading to the reactor, in a line pumping the reactor, or in the polymer being discharged from the polymerization reactor.

[0007] EP 2711379A1 discloses a process and apparatus for producing olefin polymers, in which an antistatic agent is metered and fed through a feed line connected to a dense bed at a feed point located in a feed zone extending upward from the top of a restriction to a distance of five times the diameter of the cross section of the dense bed above the restriction.

[0008] WO 2018 / 134007A1 describes a process for supplying a fluid to a polymer bed of a fluidized bed gas-phase polymerization reactor, in which the fluid is supplied to the polymer bed of a fluidized bed gas-phase polymerization reactor by introducing the fluid into the polymer bed through a distributor that projects into the fluidized bed zone of the reactor and terminates in a discharge end positioned such that the equation d / D>0.002 is satisfied, where d is the distance from the discharge end of the distributor to the wall of the reactor, and D is the diameter of the reactor in the fluidized bed zone.

[0009] WO 2005 / 080449A2 provides a propylene polymerization process carried out in the presence of an antifouling agent. The antifouling agent comprises one or more blocks (CH2-CH2-O) k (where each k ranges from 1 to 50) and one or more blocks (CH2-CH(R)-O) n (wherein R comprises an alkyl group having 1 to 6 carbon atoms, and each n ranges from 1 to 50). The antifouling polymer is terminated by R' and R'' end groups, where R' is PH or an alkoxy group having 1 to 6 carbon atoms, and R'' is H or an alkyl group having 1 to 6 carbon atoms, and the antifouling polymer is dissolved in a solvent comprising cyclohexane when added to a polymerization medium.

[0010] WO 2011 / 029735 A1 describes a polymerization process in which the antifouling agent is metered and fed by at least N feed lines arranged at different heights in a dense polymer bed.

[0011] International Patent Publication No. 2016 / 150997 provides a process for preparing polyolefins by polymerizing olefins in a polymerization reactor in the presence of a polymerization catalyst at a temperature of 20 to 200°C and a pressure of 0.1 to 20 MPa. In this process, the polymerization is carried out in the presence of an antistatic agent containing an alkylene oxide-derived polymer containing an average of 10 to 200 repeating units -(CH2-CHR-O)-, where R is hydrogen or an alkyl group having 1 to 6 carbon atoms. The alkylene oxide-derived polymer is a random copolymer of ethylene oxide and another alkylene oxide, in which the ratio of the ethylene oxide-derived repeating units -(CH2-CH2-O)- to the other alkylene oxide-derived repeating units -(CH2CHR'-O)- is n:m, where R' is an alkyl group having 1 to 6 carbon atoms, the ratio of alkylene oxide to 6 carbon atoms is in the range of 6:1 to 1:1, and the alkylene oxide-derived polymer is all end-groups of -OH groups. The antistatic agent is preferably introduced directly into the reactor or into a line leading to the reactor.

[0012] WO 2009 / 010413 describes a process for polymerizing olefins, which comprises the following steps: a) polymerizing at least one liquid olefin monomer in a polymerization reactor to form a polymerization slurry containing a polyolefin and the liquid monomer; b) continuously transferring the polymerization slurry from the polymerization reactor to a flash chamber through a transfer line including a pipe in which a turbulent three-phase flow containing a polymer, a liquid monomer, and a gaseous monomer is established; and c) separating the vaporized monomer from the polymer in the flash chamber, wherein step b) of this method is characterized in that a contamination inhibitor in liquid form is continuously introduced upstream of the inlet of the pipe.

[0013] Antistatic agents used in continuous olefin polymerization often not only exert the desired antistatic effect but also adversely affect the activity of virtually all olefin polymerization catalysts. Furthermore, their efficiency is limited, and even when these agents are added to polymerization, problems with sheeting and clumping due to static charging can persist in certain products, especially when preparing relatively high molecular weight polyolefins. Furthermore, it is necessary to ensure reliable operation of the polymerization reactor over a long period of time.

[0014] Therefore, there is a need to provide a polymerization process that not only prevents the formation of wall sheeting and polymer agglomerates in a polymerization reactor, but also provides good operability of the polymerization process. Summary of the Invention

[0015] The present disclosure provides a process for continuously producing a polyolefin polymer in a gas phase polymerization apparatus at a temperature of 20 to 200°C and a pressure of 0.5 to 10 MPa in the presence of a polymerization catalyst, comprising: providing a mixture of polyolefin particles and a gas; conveying the mixture through a pipe at a gas velocity of 2 m / s or greater; and - introducing an antistatic agent into the mixture.

[0016] In some embodiments, the mixture is conveyed through a pipe at a gas velocity of 50 m / s or less, preferably 40 m / s or less, more preferably 30 m / s or less, and most preferably 20 m / s or less.

[0017] In some embodiments, in this process, the density of the polyolefin particles in the gas is at least 30 kg / m 3 , preferably at least 50 kg / m 3 , more preferably at least 80 kg / m 3 In some embodiments, in this process, the density of the polyolefin particles in the gas is at most 200 kg / m 3 It is characterized in that:

[0018] In some embodiments, the process is characterized in that the pipe is a discharge line and / or a transfer line.

[0019] In some embodiments, in this process: feeding an olefin or an olefin and one or more other ethylenically unsaturated monomers to a gas phase polymerization reactor; homopolymerizing an olefin or copolymerizing an olefin with one or more other ethylenically unsaturated monomers in a gas phase reactor in the presence of a polymerization catalyst; and discharging the formed polyolefin particles from the gas phase reactor.

[0020] In some embodiments, the process is characterized in that the gas phase polymerization apparatus comprises two or more gas phase polymerization reactors, hi some embodiments, the process is characterized in that the fluidized bed reactor and the multi-zone circulating reactor are sequenced.

[0021] In some embodiments, the process is characterized in that the antistatic agent comprises an alkylene oxide-derived polymer. In one embodiment, the alkylene oxide-derived polymer contains an average of 10 to 200 —(CH—CHR—O)— units, where R is hydrogen or an alkyl group having 1 to 6 carbon atoms, and the alkylene oxide-derived polymer is a random copolymer of ethylene oxide and another alkylene oxide, in which the ratio n:m of the ethylene oxide-derived repeat unit —(CH—CH—O)— to the other alkylene oxide-derived repeat unit —(CH—CHR′—O)— (where R′ is an alkyl group having 1 to 6 carbon atoms) is 6:1 to 1:1, and all terminal groups of the alkylene oxide-derived polymer are —OH groups.

[0022] In some embodiments, the process is characterized in that the alkylene oxide-derived polymer is a random copolymer of ethylene oxide and propylene oxide, hi some embodiments, the alkylene oxide-derived polymer can be a linear ethylene oxide / propylene oxide copolymer.

[0023] In some embodiments, the process is characterized in that the antistatic agent is introduced into the mixture of gas and polyolefin in the carrier feed, and the weight ratio of antistatic agent to carrier in the combined stream introduced into the pipe is in the range of 1:5000 to 1:10.

[0024] In some embodiments, the process is characterized in that the carrier is selected from the group consisting of water, liquid hydrocarbons, preferably those having 3 to 8 carbon atoms, such as propane.

[0025] In some embodiments, the process is characterized in that the polymerization is carried out in a polymerization reactor cascade comprising a fluidized bed reactor and a multi-zone circulation reactor, wherein in the multi-zone circulation reactor, the growing polymer flows upward under fast fluidization or transport conditions through a first polymerization zone, exits said first polymerization zone and enters a second polymerization zone, where the particles flow downward under the action of gravity, exits said downcomer and is reintroduced into a riser, thereby establishing a polymer circulation, and the fluidized bed reactor is located upstream of the multi-zone circulation reactor.

[0026] In some embodiments, the process is characterized in that a low molecular weight polyolefin polymer component is obtained in a fluidized bed reactor and a high molecular weight polyolefin polymer component is obtained in a multi-zone circulating reactor.

[0027] In some embodiments, the process is characterized in that the polyolefin polymer is a polyethylene prepared by homopolymerizing ethylene or copolymerizing ethylene with up to 10 wt%, up to 5 wt%, or up to 3 wt% of a C3-C8-1-alkene.

[0028] In a further aspect, the present disclosure provides a gas phase polymerization apparatus for carrying out the process of the present disclosure, the apparatus comprising a gas phase polymerization reactor and at least one pipe, the pipe comprising at least one inlet for introducing an antistatic agent into the pipe.

[0029] In some embodiments, the apparatus includes a pipe having a receiving end for receiving a mixture of polyolefin particles and a gas and a discharge end for discharging the mixture of polyolefin particles and a gas, and at least one inlet for introducing an antistatic agent into the pipe is located within a first half of the pipe. In some embodiments, the at least one inlet may be located within a first third of the pipe from the receiving end of the pipe. [Brief explanation of the drawings]

[0030] [Figure 1] FIG. 1 shows a schematic of an exemplary setup of a polymerization reactor cascade including a fluidized bed reactor and a multi-zone circulation reactor for the polymerization process of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0031] The present disclosure provides a continuous process for the production of polyolefins, particularly, but not exclusively, a process for polymerizing 1-olefins, i.e., hydrocarbons having terminal double bonds. The monomer may be a functionalized olefinically unsaturated compound such as an ester or amide derivative of acrylic or methacrylic acid, e.g., an acrylate, methacrylate, or acrylonitrile. The monomer may be, in particular, a non-polar olefinic compound, including aryl-substituted 1-olefins. Particularly preferred 1-olefins are linear or branched C2-C6 12 -1-Alkenes, especially straight chain C2-C 10 1-Alkenes, such as ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-decene, or branched chain C2-C6 10 Examples of suitable olefins include 1-alkenes such as 4-methyl-1-pentene, conjugated and non-conjugated dienes such as 1,3-butadiene, 1,4-hexadiene, or 1,7-octadiene, or vinyl aromatic compounds such as styrene or substituted styrenes. It is also possible to polymerize mixtures of various 1-olefins. Olefins can also include those in which the double bond is part of a cyclic structure, which can have one or more ring systems. Examples include cyclopentene, norbornene, tetracyclododecene, methylnorbornene, or dienes such as 5-ethylidene-2-norbornene, norbornadiene, and ethylnorbornadiene. It is also possible to polymerize mixtures of two or more olefins.

[0032] This process is particularly suitable for the homopolymerization or copolymerization of ethylene or propylene, and is particularly preferred for the homopolymerization or copolymerization of ethylene. The comonomer in the propylene polymerization can be, for example, up to 40% by weight of ethylene and / or 1-butene, preferably 0.5% to 35% by weight of ethylene and / or 1-butene, based on the total weight of the monomers and comonomers. In the ethylene polymerization, the comonomer is preferably a C3-C8-1-alkene, particularly 1-butene, 1-pentene, 1-hexene, and / or 1-octene, in an amount of up to 20% by weight, more preferably 0.01% to 15% by weight, and particularly preferably 0.05% to 12% by weight, based on the total weight of the monomers and comonomers. Particularly preferred is a process in which ethylene is copolymerized with 0.1% to 12% by weight of 1-hexene and / or 1-butene, based on the total weight of the monomers and comonomers.

[0033] The polymerization of olefins is carried out in the presence of a polymerization catalyst. Any conventional olefin polymerization catalyst can be used in the process of the present disclosure. That is, polymerization can be carried out using a chromium oxide-based Phillips catalyst, a titanium-based Ziegler or Ziegler-Natta catalyst, or a single-site catalyst. For purposes of this disclosure, a single-site catalyst is a catalyst based on a chemically uniform transition metal coordination compound. Furthermore, it is possible to use a mixture of two or more of these catalysts in the polymerization of olefins. Such a mixed catalyst may be referred to as a hybrid catalyst. The preparation and use of these catalysts for olefin polymerization is generally known.

[0034] The catalyst used in the disclosed process may be, for example, a Phillips-type catalyst, which can be prepared by applying a chromium compound to an inorganic support and then calcining it at temperatures between 350 and 950°C, thereby converting chromium present in valences less than six to a hexavalent state. In addition to chromium, elements such as magnesium, calcium, boron, aluminum, phosphorus, titanium, vanadium, zirconium, and zinc can also be used. Titanium, zirconium, and zinc are particularly preferred. Combinations of the above elements are also possible. The catalyst precursor can be doped with fluoride before or during calcination. Supports for Phillips catalysts may include aluminum oxide, silicon dioxide (silica gel), titanium dioxide, zirconium dioxide, or mixed oxides or cogels thereof, or aluminum phosphate, as known to those skilled in the art. Further suitable support materials can be obtained by modifying the pore surface area, for example, with compounds of boron, aluminum, silicon, or phosphorus. In one embodiment, the support material can be silica gel. In one embodiment, the silica gel can be spherical or granular, the former of which can also be spray-dried. The activated chromium catalyst can then be pre-polymerized or pre-reduced. Pre-reduction can be carried out in an activator using cobalt or hydrogen at temperatures between 250 and 500°C, preferably between 300 and 400°C.

[0035] The catalyst for the process of the present disclosure can be a single-site catalyst. Particularly suitable are catalysts containing bulky sigma- or pi-bonded organic ligands, such as catalysts based on mono-Cp complexes, catalysts based on bis-Cp complexes, commonly referred to as metallocene catalysts, or catalysts based on late transition metal complexes, especially iron bis-imine complexes. More preferred catalysts are mixtures of two or more single-site catalysts, or mixtures of different types of catalysts, including at least one single-site catalyst.

[0036] Preferred catalysts are also Ziegler-type catalysts, preferably comprising a titanium or vanadium compound, a magnesium compound, and optionally an electron donor compound and / or a particulate inorganic oxide as a support. Surprisingly, it has been found that these types of catalysts are particularly suitable for combination with antistatic agents, in particular antistatic agents comprising copolymers of ethylene oxide and propylene oxide.

[0037] The titanium compound can be a halide or alkoxide of trivalent or tetravalent titanium, or a titanium alkoxyhalide or a mixture of various titanium compounds. Examples of such titanium compounds include TiBr3, TiBr4, TiCl3, TiCl4, Ti(OCH3)Cl3, Ti(OC2H5)Cl3, Ti(Oi-C3H7)Cl3, Ti(On-C4H9)C|3, Ti(OC2H5)Br3, Ti(On-C4H9)Br3, Ti(OCH3)2Cl2, Ti(OC2H5)2C|2, Ti(On-C4H9)2C|2, Ti(OC2H5)2Br2, Ti(OCH3)3Cl, Ti(OC2H5)3Cl, Ti(On-C4H9)3Cl, Ti(OC2H5)3Br, Ti(OCH3)4, Ti(OC2H5)4, or Ti(On-C4H9)4. In some embodiments, the titanium compound may contain chlorine as the halogen. In some embodiments, the titanium compound may be a titanium halide containing only halogens in addition to titanium, and among these, titanium chloride, especially titanium tetrachloride, may be mentioned. Among vanadium compounds, vanadium halides, vanadium oxyhalides, vanadium alkoxides, and vanadium acetylacetonates may be mentioned. In some embodiments, the vanadium compound may be a vanadium compound having an oxidation state of 3 to 5.

[0038] In the preparation of the solid component, at least one magnesium compound can be additionally used. This type of compound can be a halogen-containing magnesium compound, such as a magnesium halide, particularly a chloride or bromide, and a magnesium compound from which the magnesium halide is obtained by a conventional method, such as by reacting with a halogenating agent. For the purposes of the present invention, a halogen is chlorine, bromine, iodine, fluorine, or a mixture of two or more halogens. In some embodiments, the halogen can be chlorine or bromine, particularly chlorine.

[0039] The halogen-containing magnesium compound may be, in particular, magnesium chloride or magnesium bromide. Magnesium compounds from which halides can be obtained include, for example, magnesium alkyls, magnesium aryls, magnesium alkoxy compounds, magnesium aryloxy compounds, or Grignard compounds. The halogenating agent may, for example, be a halogen, hydrogen halide, SiCl4 or CCl4, in particular chlorine or hydrogen chloride.

[0040] Examples of halogen-free magnesium compounds include diethyl magnesium, di-n-propyl magnesium, diisopropyl magnesium, di-n-butyl magnesium, di-sec-butyl magnesium, di-tert-butyl magnesium, diamyl magnesium, n-butylethyl magnesium, n-butyl-sec-butyl magnesium, n-butyloctyl magnesium, diphenyl magnesium, diethoxy magnesium, di-n-propyloxy magnesium, diisopropyloxy magnesium, di-n-butyloxy magnesium, di-sec-butyloxy magnesium, di-tert-butyloxy magnesium, diamyloxy magnesium, n-butyloxyethoxy magnesium, n-butyloxy-sec-butyloxy magnesium, n-butyloxyoctyloxy magnesium, and diphenoxy magnesium. Among these, it is preferred to use n-butylethyl magnesium or n-butyloctyl magnesium.

[0041] Examples of Grignard compounds include methylmagnesium chloride, ethylmagnesium chloride, ethylmagnesium bromide, ethylmagnesium iodide, n-propylmagnesium chloride, n-propylmagnesium bromide, n-butylmagnesium chloride, n-butylmagnesium bromide, sec-butylmagnesium chloride, sec-butylmagnesium bromide, tert-butylmagnesium chloride, tert-butylmagnesium bromide, hexylmagnesium chloride, octylmagnesium chloride, amylmagnesium chloride, isoamylmagnesium chloride, phenylmagnesium chloride and phenylmagnesium bromide.

[0042] As the magnesium compound for producing the granular solid, in addition to magnesium dichloride or magnesium dibromide, di(C1-C 10 Preferably, a magnesium compound having an alkyl group is used. Preferably, the Ziegler-Natta catalyst comprises a transition metal selected from titanium, zirconium, vanadium, and chromium.

[0043] Electron donor compounds for preparing Ziegler-type catalysts can include, for example, alcohols, glycols, esters, ketones, amines, amides, nitriles, alkoxysilanes, aliphatic ethers, etc. These electron donor compounds can be used alone or in combination with other electron donor compounds.

[0044] In some embodiments, the alcohol has the formula R 1 OH, where R 1 The group is C1-C 20 In some embodiments, R 1 is C1~C 20-alkyl groups. Specific examples include methanol, ethanol, isopropanol, n-butanol, and the like. In some embodiments, the glycol has a total of less than 50 carbon atoms. In some embodiments, the glycol can be a 1,2 or 1,3 glycol having a total of less than 25 carbon atoms. Specific examples include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, and the like. In some embodiments, the ester is a C1- 20 Alkyl esters of aliphatic carboxylic acids, in particular C1-C8-alkyl esters of aliphatic monocarboxylic acids such as ethyl acetate, methyl formiate, ethyl formiate, methyl acetate, propyl acetate, i-propyl acetate, n-butyl acetate, i-butyl acetate, etc. In some embodiments, the amine has the formula NR 2 3, wherein R 2 The groups are independently hydrogen or C1-C 20 -hydrocarbon group, provided that R 2 The groups are not hydrogen at the same time. 2 is C1~C 10 and alkyl groups. Specific examples include diethylamine, diisopropylamine, triethylamine, and the like. In some embodiments, the amide has the formula R 3 CONR 4 2, wherein R 3 and R 4 are independently hydrogen or C1-C 20 is a hydrocarbon group. Specific examples include formamide and acetamide. In some embodiments, the nitrile is represented by the formula R 1 CN, wherein R 1 has the same meaning as above. A specific example is acetonitrile. In some embodiments, the alkoxysilane has the formula R 5 a R 6 b Si(OR 7 ) cwhere a and b are integers from 0 to 2, c is an integer from 1 to 4, and the sum (a+b+c) is 4; R 5 , R 6 , and R 7 is an alkyl, cycloalkyl, or aryl radical having 1 to 18 carbon atoms, optionally containing heteroatoms. Particularly preferred are those where a is 0 or 1, c is 2 or 3, and R 6 is an alkyl or cycloalkyl group, optionally containing heteroatoms, and R 7 is a silicon compound in which R is methyl. Examples of such silicon compounds include methyltrimethoxysilane, dimethyldimethoxysilane, trimethylmethoxysilane, and t-butyltrimethoxysilane. In some embodiments, the electron donor compound is selected from the group consisting of amides, esters, and alkoxysilanes.

[0045] Ziegler-type catalysts can be polymerized in the presence of a cocatalyst. Such cocatalysts can be organometallic compounds of metals in Groups 1, 2, 12, 13, or 14 of the Periodic Table, particularly organometallic compounds of metals in Group 13, especially organoaluminum compounds. In some embodiments, the cocatalyst is, for example, an organometallic alkyl, organometallic alkoxide, or organometallic halide. In some embodiments, organometallic compounds include lithium alkyls, magnesium or zinc alkyls, magnesium alkyl halides, aluminum alkyls, silicon alkyls, silicon alkoxides, and silicon alkyl halides. In some embodiments, organometallic compounds can include aluminum alkyls and magnesium alkyls. In some embodiments, organometallic compounds can include aluminum alkyls, such as trialkylaluminum compounds. Aluminum alkyls include, for example, trimethylaluminum, triethylaluminum, triisobutylaluminum, and tri-n-hexylaluminum.

[0046] The resulting polyolefin particles have a more or less regular shape and size, depending on the catalyst morphology and size and the polymerization conditions. Depending on the catalyst used, the average diameter of the polyolefin particles typically ranges from several hundred to several thousand micrometers. For chromium catalysts, the average particle size is typically about 300 to about 1600 μm, and for Ziegler-type catalysts, the average particle size is typically about 500 to about 3000 μm.

[0047] The process of the present disclosure is carried out as a gas-phase polymerization, i.e., a process in which a solid polymer is obtained from the gas phase of a monomer or monomers. Such gas-phase polymerization can be carried out at a pressure of 0.1 to 20 MPa, preferably 0.5 to 10 MPa, and particularly 1.0 to 5 MPa, and at a polymerization temperature of 40 to 150°C, preferably 65 to 125°C.

[0048] The process of the present disclosure can be carried out, for example, in an apparatus comprising two or more gas phase polymerization reactors, particularly a sequence of a fluidized bed reactor and a multi-zone circulating reactor.

[0049] A fluidized-bed polymerization reactor is a reactor in which polymerization takes place in a bed of polymer particles maintained in a fluidized state by supplying gas to the bottom of the reactor (usually below a gas distribution grid, which distributes the gas flow) and withdrawing it again from the top. The reactor gas is then returned to the bottom of the reactor via a recycle line equipped with a compressor and a heat exchanger. The recycled reactor gas is usually a mixture of the olefin to be polymerized, an inert gas such as nitrogen, and / or a lower alkane such as ethane, propane, butane, pentane, or hexane, and optionally a molecular weight regulator such as hydrogen. Nitrogen or propane is preferably used as the inert gas, and, if appropriate, a lower alkane is also used. The reactor gas velocity must be high enough, first, to fluidize the mixed bed of fine polymer present in the tubes that function as the polymerization zone, and second, to effectively remove the heat of polymerization. The polymerization can also be carried out in a condensed or hypercondensed mode, where a portion of the recycled reaction gas is cooled below the dew point and returned to the reactor either separately as liquid and gas phases or together as a two-phase mixture, further utilizing the enthalpy of vaporization to cool the reaction gas.

[0050] A multi-zone circulation reactor is a gas-phase reactor in which two polymerization zones are interconnected and the polymer passes through these two zones alternately multiple times. Such reactors are described, for example, in International Patent Publications WO 97 / 04015 A1 and WO 00 / 02929 A1. They contain two interconnected polymerization zones: a riser, through which growing polymer particles flow upward under high-speed fluidization or transport conditions, and a downcomer, through which growing polymer particles flow in a dense form under the action of gravity. Polymer particles exiting the riser enter the downcomer, and those exiting the downcomer are reintroduced into the riser, thereby establishing a polymer circulation between the two polymerization zones, with the polymer passing through these two zones alternately multiple times. Furthermore, by establishing different polymerization conditions in the riser and downcomer, the two polymerization zones of a single multi-zone circulation reactor can be operated under different polymerization conditions. To this end, the gas mixture leaving the riser and containing the polymer particles can be partially or completely prevented from entering the downcomer. This can be achieved, for example, by supplying a barrier fluid in the form of a gas and / or liquid mixture into the downcomer, such as at the top of the downcomer. The barrier fluid must have a different composition from the gas mixture present in the riser. The amount of barrier fluid added can be adjusted so that an upward flow of gas countercurrent to the flow of polymer particles is generated, particularly at the top, acting as a barrier against the gas mixture entrained among the particles coming from the riser. In this way, two zones with different gas compositions can be obtained in a single multi-zone circulating reactor. Furthermore, it is also possible to introduce make-up monomer, comonomer, molecular weight regulators such as hydrogen, and / or inert fluids at any point in the downcomer, particularly below the barrier feed point. Therefore, various monomer, comonomer, and hydrogen concentrations can be easily created along the downcomer, further differentiating the polymerization conditions.

[0051] When carried out in two or more gas-phase polymerization reactors, the process of the present disclosure may further include a step of transferring the polymer particles from one reactor to another. An antistatic agent may be introduced directly into the transfer line to prevent agglomeration and line clogging.

[0052] In an exemplary embodiment of the present disclosure, the fluidized bed reactor is located upstream of the multi-zone circulating reactor. Such a reactor cascade of gas-phase reactors may further comprise additional polymerization reactors. These additional reactors may be any type of low-pressure polymerization reactor, such as a gas-phase reactor or a suspension reactor, and may also include a prepolymerization stage.

[0053] In an exemplary embodiment, the process of the present disclosure comprises: feeding an olefin or an olefin and one or more other ethylenically unsaturated monomers to a gas phase polymerization reactor; transferring polymer particles from one gas phase reactor to another gas phase reactor; and - discharging the formed polyolefin particles from the gas phase reactor.

[0054] The antistatic agent of the present disclosure can be introduced into the reactor using conventional methods. It can be fed directly into the reactor or into a line leading to the reactor. During the course of this disclosure, it was surprisingly discovered that in addition to the location at which the antistatic agent is introduced into the polyolefin particle / gas mixture, the velocity of the gas is also important for effectively dispersing the antistatic agent to maximize its effectiveness. Therefore, the polyolefin particle / gas mixture is conveyed through the polymerization apparatus at a velocity of 2 m / s or more, preferably 2.5 m / s or more.

[0055] The method of introducing the antistatic agent into the polymerization reactor can vary depending on the polymer being produced. In the case of polyethylene production, the antistatic agent can be introduced into the polymerization reactor, for example, via a liquid carrier stream. The liquid carrier stream, also known as a pickup stream, can be a stream of a liquid hydrocarbon containing 3 to 8 carbon atoms, such as propane. In some embodiments, the weight ratio of antistatic agent to liquid carrier in the combined stream introduced into the reactor is less than 1:5, more preferably in the range of 1:5000 to 1:10, even more preferably in the range of 1:2000 to 1:20, and most preferably in the range of 1:1000 to 1:50. In some embodiments, the combined feed stream containing the liquid carrier and the antistatic agent does not contain an organoaluminum compound, such as an aluminum alkyl. In a preferred embodiment of the present disclosure, a static mixer is provided in the feed line for introducing the combined feed stream containing the liquid carrier and the antistatic agent into the gas-phase polymerization reactor, and the combined feed stream passes through the static mixer before being introduced into the gas-phase polymerization reactor.

[0056] In another embodiment, the antistatic agent is introduced with the monomer and / or comonomer stream.

[0057] According to one embodiment of the present disclosure, the polymerization is a gas phase polymerization and the antistatic agent is a polymer having a density of the solid polymer particles of at least 30 kg / m 3 , preferably at least 50 kg / m 3 , more preferably at least 80 kg / m 3 The antistatic agent is introduced into the gas-phase polymerization reactor by feeding it to a portion of the reactor that is 0.05 to 0.05 mm. In some embodiments, the portion of the gas-phase polymerization reactor to which the antistatic agent is fed is, for example, a portion containing a stirred or fluidized bed of polymer particles. Another portion of the gas-phase polymerization reactor to which the antistatic agent can be fed according to this embodiment is the riser or downcomer of a multi-zone circulating reactor.

[0058] In one embodiment, the antistatic agent may be supplied to a polymerization reactor in addition to being supplied to a pipe conveying a mixture of polyolefin particles and gas at a speed of 2 m / s or more, preferably 2.5 m / s or more. Preferably, the pipe is a transfer line transferring the mixture from one polymerization reactor to the next, or a discharge line for discharging the mixture, for example, to a collection vessel, degassing vessel, and / or recovery vessel. A high transport speed of 2 m / s or more may increase the electrostatic load of the polyolefin particles in the mixture. However, by additionally injecting the antistatic agent into the pipe, the antistatic agent can be effectively dispersed in the mixture, effectively reducing the electrostatic load of the polyolefin particles and preventing wall sheeting and clogging in the pipe and in subsequent vessels that come into contact with the mixture discharged from the pipe.

[0059] The antistatic agent used in the process of the present disclosure may include an alkylene oxide-derived polymer. In one embodiment, the alkylene oxide-derived polymer contains an average of 10 to 200 repeating units -(CH2-CHR-O)-, where R is hydrogen or an alkyl group having 1 to 6 carbon atoms, and the alkylene oxide-derived polymer is a random copolymer of ethylene oxide and another alkylene oxide, in which the ratio n:m of the repeating units -(CH2-CH2-O)- derived from ethylene oxide to the repeating units -(CH2-CHR'-O)- (where R' is an alkyl group having 1 to 6 carbon atoms) derived from another alkylene oxide is 6:1 to 1:1, and all of the alkylene oxide-derived polymer end groups are -OH groups.

[0060] As an example, the alkylene oxide-derived polymer is a random copolymer of ethylene oxide and propylene oxide, such as a linear ethylene oxide / propylene oxide copolymer.

[0061] In an exemplary embodiment of the present disclosure, polymerization is carried out in a cascade of a fluidized-bed reactor and a multi-zone circulating reactor, with the polymerization reactors operated under different polymerization conditions, particularly different concentrations of molecular weight regulators such as hydrogen. Thus, polymerization in a high-hydrogen-concentration reactor results in a lower molecular weight polyolefin polymer component, while polymerization in a low-hydrogen-concentration reactor results in a higher molecular weight polyolefin polymer component. Preferably, the fluidized-bed reactor produces a lower molecular weight polyolefin polymer component, while the multi-zone circulating reactor produces a higher molecular weight polyolefin polymer component. Thus, the fluidized-bed reactor can be operated with a higher hydrogen concentration to produce a lower molecular weight polyolefin polymer component, and the multi-zone circulating reactor can be operated with a lower hydrogen concentration to produce a lower molecular weight polyolefin polymer component. The polyolefin polymers prepared by the process of the present disclosure have an MFR (Miller Free Radical) of 190°C and 21.6 kg load according to DIN EN ISO 1133:2005. 21.6 The polyethylene preferably has a MFR in the range of 0.5 g / 10 min to 350 g / 10 min, more preferably in the range of 1.0 g / 10 min to 40 g / 10 min, or in the range of 120 g / 10 min to 250 g / 10 min. 21.6 The viscosity is in the range of 1.2 g / 10 min to 35 g / 10 min, particularly in the range of 1.5 g / 10 min to 10 g / 10 min. The density is 0.935 g / cm 3 ~0.970g / cm 3 In some embodiments, more preferably, the range is 0.945 g / cm 3 ~0.968g / cm 3 The range is.

[0062] The process of the present disclosure can be for the homopolymerization of ethylene or the copolymerization of ethylene with up to 20 wt% of C3-C8-1-alkenes.

[0063] The process of the present disclosure may be used to prepare polyethylene in a polymerization reactor cascade, in which a fluidized bed reactor is disposed upstream of a multi-zone circulating reactor, and the fluidized bed reactor has an MFR in the range of 0.1 g / 10 min to 300 g / 10 min, more preferably 1 g / 10 min to 100 g / 10 min, at a temperature of 190° C. and a load of 2.16 kg. 2.16 An ethylene homopolymer or copolymer having the formula:

[0064] The process of the present disclosure allows for the preparation of polyolefin polymers by gas phase polymerization in a polymerization reactor cascade comprising a fluidized bed reactor and a multi-zone circulating reactor, thereby preventing or at least significantly reducing the formation of polymer aggregates in the polymerization reactor and fluctuations in the hydrodynamics of the multi-zone circulating reactor.

[0065] In another aspect, the present disclosure provides a gas phase polymerization apparatus for carrying out the process of the present disclosure, the gas phase polymerization reactor comprising a gas phase polymerization reactor and at least one pipe, the pipe being equipped with at least one inlet for introducing an antistatic agent into the pipe.

[0066] In an exemplary embodiment, the pipe includes a receiving end for receiving the mixture of polyolefin particles and gas and a discharge end for discharging the mixture of polyolefin particles and gas, and at least one inlet is located within the first half, particularly the first third, of the pipe from the receiving end of the pipe. It has been found that such a distance between the receiving end and the inlet allows for particularly good dispersion of the antistatic agent on the polymer particles, resulting in reduced wall sheeting and agglomeration of the polymer particles.

[0067] The present disclosure will be described in further detail with reference to FIG. 1, without being understood to limit the scope and spirit of the disclosure.

[0068] FIG. 1 shows a schematic diagram of an exemplary embodiment of a polymerization reactor cascade setup including a fluidized bed reactor and a multi-zone circulation reactor for carrying out the process of the present disclosure, with arrows indicating exemplary introduction points for antistatic agents.

[0069] The first gas-phase reactor, a fluidized-bed reactor (1), contains a fluidized bed of polyolefin particles (2), a gas distribution grid (3), and a velocity reduction zone (4). The velocity reduction zone (4) has a larger diameter than the fluidized-bed section of the reactor. The polyolefin bed is kept fluidized by an upward flow of gas supplied through a gas distribution grid (3) located at the bottom of the reactor (1). The reaction gas stream exiting the top of the velocity reduction zone (4) via a recycle line (5) is compressed by a compressor (6) and transferred to a heat exchanger (7), where it is cooled and recycled to the bottom of the fluidized-bed reactor (1), below the gas distribution grid (3) at position (8). If appropriate, the recycle gas can be cooled below the dew point of one or more of the recycle gas components in the heat exchanger to operate the reactor in condensed matter, i.e., condensed mode. In addition to unreacted monomer, the recycle gas may also contain inert condensable gases, such as alkanes, and inert non-condensable gases, such as nitrogen. Make-up monomer, molecular weight regulator, and any inert gas or process additives can be fed to reactor (1) at various locations, for example, via one or more lines (9) to the recycle line (5) upstream of compressor (6) or via line (9a) to the polymer bed within fluidized-bed reactor (1), without limiting the scope of this disclosure. Catalyst can be fed to reactor (1) via line (10), which can be located below fluidized bed (2).

[0070] The polyolefin particles obtained in the fluidized-bed reactor (1) are discontinuously discharged via line (11) and fed to a solid / gas separator (12) to avoid the gas mixture coming from the fluidized-bed reactor (1) entering the second gas-phase reactor. Line (11) has been found to be a suitable point for the introduction of an antistatic agent. The gas leaving the solid / gas separator (12) is discharged as off-gas from the reactor via line (13), and the separated polyolefin particles are fed to the second gas-phase reactor via line (14).

[0071] The second gas-phase reactor is a multi-zone circulating gas-phase reactor (31) with two reaction zones, a riser (32) and a downcomer (33), through which the polyolefin particles repeatedly pass. In the riser (32), the polyolefin particles flow upward in the direction of arrow (34) under high-velocity fluidization conditions. In the downcomer (33), the polyolefin particles flow downward in the direction of arrow (35) under the influence of gravity. The riser (32) and the downcomer (33) are suitably interconnected by interconnecting bends (36) and (37).

[0072] After passing through the riser (32), the polyolefin particles and gas mixture exit the riser (32) and are conveyed to a solid / gas separation zone (38). This solid / gas separation can be accomplished using conventional separation means, such as a centrifugal separator, e.g., a cyclone. From the separation zone (38), the polyolefin particles enter a downcomer (33).

[0073] The gas mixture leaving the separation zone (38) is recycled to the riser (32) via a recycle line (39) equipped with a compressor (40) and a heat exchanger (41). Downstream of the heat exchanger (41), the recycle line (39) branches, splitting the gas mixture into two separate streams: line (42) carries a portion of the recycle gas to the interconnecting bend (37), and line (43) carries another portion of the recycle gas to the bottom of the riser (32), establishing rapid fluidization conditions within the riser. Polyolefin particles coming from the first gas-phase reactor via line (14) enter the multi-zone cyclic gas-phase reactor (31) through the interconnecting bend (37) at position (44).

[0074] Make-up monomer, make-up comonomer, and optionally inert gas or process additives can be fed to the multi-zone circulation reactor (31) via one, two, or more lines (45) or (46) suitably located at any point in the gas recycle line (39) or the downcomer (33). A possible route for feeding process additives, such as antistatic agents, is to further feed the additive via line (47).

[0075] A portion of the gas mixture leaving the separation zone (38) exits through a recycle line (39) after the compressor (40) and is transferred through line (48) to a heat exchanger (49) where the mixture is cooled to a temperature at which the monomer and any inert gases are partially condensed. A separation vessel (50) is located downstream of the heat exchanger (49). The separated gas mixture is recycled to the recycle line (39) through line (51), and the separated liquid is fed by a pump (53) to the downcomer (33) through line (52).

[0076] The polyolefin particles obtained in the multi-zone circulation reactor (31) are continuously discharged from the bottom of the downcomer (33) via the discharge line (54), which has been found to be another suitable point for introducing the antistatic agent.

[0077] By selecting the discharge lines (11) and / or (54) as the introduction point for the antistatic agent, in combination with conveying the mixture of polyolefin particles and gas at a speed of 2 m / s or more, it is possible to avoid the formation of wall sheets and polymer agglomerates without affecting the operability of the polymerization process.

Claims

1. A process for continuously producing polyolefin polymers in a gas phase polymerization apparatus in the presence of a polymerization catalyst at a temperature of 20 to 200°C and a pressure of 0.5 to 10 MPa, comprising: providing a mixture of polyolefin particles and a gas; transporting said mixture through a pipe at a gas velocity of 2 m / s or greater; and • introducing an antistatic agent into said mixture.

2. The density of the polyolefin particles in the gas is at least 30 kg / m ３ , preferably at least 50 kg / m ３ , more preferably at least 80 kg / m ３ The process according to claim 1, characterized in that:

3. 10. A process according to any one of the preceding claims, characterized in that the pipes are discharge and / or transfer lines.

4. The process comprises: feeding an olefin or an olefin and one or more other ethylenically unsaturated monomers into said gas phase polymerization reactor; homopolymerizing said olefin or copolymerizing said olefin with said one or more other ethylenically unsaturated monomers in said gas phase reactor in the presence of a polymerization catalyst; 4. The process according to any one of the preceding claims, further comprising the step of: - discharging the formed polyolefin particles from the gas phase reactor.

5. 10. The process according to any one of the preceding claims, characterized in that the gas phase polymerization apparatus comprises two or more gas phase polymerization reactors, preferably a sequence of a fluidized bed reactor and a multi-zone circulating reactor.

6. 10. The process of claim 1, wherein the antistatic agent comprises an alkylene oxide-derived polymer.

7. 7. The process of claim 6, wherein the alkylene oxide-derived polymer is a random copolymer of ethylene oxide and propylene oxide, preferably a linear ethylene oxide / propylene oxide copolymer.

8. 10. The process according to any one of the preceding claims, characterized in that the antistatic agent is introduced into a mixture of gas and polyolefin in a feed of liquid carrier, the weight ratio of antistatic agent to liquid carrier in the combined stream introduced into the pipe preferably ranging from 1:5000 to 1:

10.

9. 9. The process of claim 8, wherein the liquid carrier is selected from the group consisting of water, preferably a liquid hydrocarbon having 3 to 8 carbon atoms, such as propane.

10. 10. The process according to claim 9, wherein the polymerization is carried out in a polymerization reactor cascade comprising a fluidized bed reactor and a multi-zone circulation reactor, in which the growing polymer flows upward under fast fluidization or transport conditions through a first polymerization zone, exits the first polymerization zone and enters a second polymerization zone, where the particles flow downward under the action of gravity, exits a downcomer and is reintroduced into a riser, thereby establishing a circulation of the polymer, and the fluidized bed reactor is located upstream of the multi-zone circulation reactor.

11. 11. The process of claim 10, wherein the fluidized bed reactor provides a low molecular weight polyolefin polymer component and the multi-zone circulating reactor provides a high molecular weight polyolefin polymer component.

12. The polyolefin polymer may be a copolymer of ethylene and up to 10% by weight of C ３ ~C ８ 3. The process according to claim 1, wherein the polyethylene is prepared by copolymerizing 1-alkene with 1-alkene.

13. 10. The process according to claim 9, wherein the at least one gas-phase polymerization reactor is supplied with the antistatic agent in addition to the antistatic agent being supplied to a pipe conveying the mixture at a gas velocity of at least 2 m / s.

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