Process for the polymerization of olefins and polyolefins

Abstract

This invention belongs to the field of polyolefin preparation technology, and particularly relates to an olefin polymerization method and a polyolefin. The method includes: (1) coordination polymerization of olefin monomers or comonomers in the presence of a polymerization catalyst and hydrogen; (2) a deep polymerization reactor connected in series at the end of the polymerization reactor in step (1), wherein the material at the outlet of the polymerization reactor in step (1) is introduced into the deep polymerization reactor and a catalyst modifier is added therein to continue deep polymerization to produce ultra-high molecular weight components and obtain polyolefins; the length-to-diameter ratio of the deep polymerization reactor is 2-15, and it is equipped with a stirring blade assembly; the phase of each stirring blade assembly is staggered from the phase of the next stirring blade assembly along the axis; the blade width is 50-600 mm. This invention improves the performance of polyolefin products and can utilize an additional 1%-30% of the catalyst efficiency, avoiding resource waste.

Description

Technical Field

[0001] This invention belongs to the field of polyolefin preparation technology, and particularly relates to an olefin polymerization method and a polyolefin. Background Technology

[0002] Currently, the mainstream processes for olefin coordination polymerization mainly include: gas-phase process, slurry process, and slurry-gas phase combination process. These processes primarily employ traditional Ziegler-Natta catalysts (ZN catalysts) or metallocene catalysts, using hydrogen as a chain transfer agent to produce polyolefin products such as polyethylene and polypropylene.

[0003] Taking polyethylene as an example, the main representatives of gas-phase processes include: Unipol gas-phase fluidized bed process from Univation Technologies (USA), Innovene G gas-phase process from BP (UK), Spherilene gas-phase process from LyondellBasell (Netherlands), and SGPE gas-phase fluidized bed process from Sinopec (China); the main representative of slurry processes is MarTECH single-loop or double-loop slurry process from Chevron-Phillips (USA). TM Examples of slurry-gas phase combined processes include SL and ADL, the Innovene S process from Ineos (UK), and the Hostlalen (ACP) process from LyondellBasell (Netherlands); representative slurry-gas phase combined processes include the Borstar process from Borealis (Austria), the Hyperizone multi-zone circulating reactor process from LyondellBasell (Netherlands), and the CX low-pressure slurry process from Mitsui Chemicals (Japan).

[0004] Taking polypropylene as an example, the main representatives of gas-phase processes include: Grace's Unipol process (USA), BP's Innovene process (UK), JPP's Horizone process (Japan), LyondellBasell's Spherizone process (Netherlands), CB&I Lummus's Novolen vertical stirred bed process (Germany), and Huafu's SPG process (China). The main representative of slurry processes is LyondellBasell's Spheripol process (Netherlands). Representatives of slurry-gas phase combined processes include LyondellBasell's Spheripol loop slurry + gas-phase fluidized bed combined process (Netherlands), Borealis's Borstar double loop + dual gas phase process (Austria), Mitsui Chemicals' Hypol stirred tank slurry + gas-phase fluidized bed process (Japan), and Sinopec's ST loop + gas phase technology process (China).

[0005] The polymerization processes for polyethylene and polypropylene listed above, exceeding 70%, all utilize Zn or metallocene catalysts. The polymerization principle follows the coordination polymerization mechanism: the active center is activated by the reduction of an alkylaluminum compound, initiating coordination of olefin monomers to the vacancy at the active center, resulting in chain growth and the formation of long-chain polyolefin molecules. When these long-chain polyolefin molecules with active centers encounter hydrogen gas, a chain transfer reaction occurs, transferring the active center to a hydrogen molecule to further initiate the polymerization of other monomers. The chain terminates when the end group of the long-chain polyolefin molecule accepts a hydrogen atom for saturation, thus generating polyolefins. By controlling the polymerization with hydrogen gas, a variety of polyolefin products with different molecular weights and molecular weight distributions can be obtained.

[0006] The polymerization processes mentioned above generally follow the chain initiation, chain propagation, chain transfer, and chain termination process. However, in continuous polymerization reactions, the material exiting the polymerization reactor still contains unreacted monomers, hydrogen, and polymerization catalyst, providing conditions for continued reaction. The aforementioned polymerization processes directly perform gas-solid or gas-liquid-solid separation on the reactor outlet material, deactivating and killing unresponsive catalyst active centers, then degassing to remove residual monomers and low-molecular-weight components before extrusion granulation and packaging. Existing polymerization processes do not consider further utilizing the reactivity of the reactor outlet material to generate higher-performance polyolefins, resulting in catalyst waste.

[0007] Therefore, how to utilize the reactivity of the effluent from the olefin polymerization reactor is a direction worthy of research. Summary of the Invention

[0008] The purpose of this invention is to provide an olefin polymerization method and polyolefins to address the issue of low catalyst efficiency in olefin polymerization. This method not only improves the quality and performance of polyolefin products (while improving the mechanical properties of polyolefin products, the uniformity of particle size distribution of the resulting powder is also improved), but also fully utilizes an additional 1%-30% of the catalyst efficiency, avoiding resource waste and reducing production costs.

[0009] To achieve the above objectives, the present invention provides the following technical solution:

[0010] In the first aspect, a method for olefin polymerization is provided, comprising the following steps:

[0011] (1) In a polymerization reactor, in the presence of a polymerization catalyst and hydrogen, olefin monomers undergo coordination polymerization, or olefin monomers undergo coordination polymerization with one or more comonomers.

[0012] (2) A deep polymerization reactor is connected in series at the end of the polymerization reactor described in step (1). Before the material from the outlet of the polymerization reactor described in step (1) undergoes gas-solid separation or gas-liquid-solid separation, the material after the polymerization reaction in step (1) is introduced into the deep polymerization reactor, and a catalyst modifier is added thereto to quickly eliminate chain transfer agents (such as hydrogen) in the reactant system, so that the reactants in the material continue to undergo deep polymerization reaction, producing ultra-high molecular weight components, and obtaining polyolefins; wherein:

[0013] The deep polymerization reactor is a horizontal deep polymerization reactor with a length-to-diameter ratio of 2 to 15 (e.g., 3, 4, 5, 6, 7, 8, 9, 10, 12, 14), preferably 5 to 6;

[0014] The deep polymerization reactor has a stirring shaft and several stirring blades; two stirring blades are arranged at 180° on the same phase of the stirring shaft, which is called a stirring blade group; the phase of each stirring blade group is staggered by 90°, 60° or 45° from the phase of the next stirring blade group along the stirring shaft; the width of the blades is 50-600mm (e.g. 55mm, 60mm, 80mm, 100mm, 200mm, 300mm, 350mm, 400mm, 450mm, 500mm, 550mm).

[0015] According to the olefin polymerization method provided by the present invention, in some embodiments, the upper part of the deep polymerization reactor in step (2) is provided with 0-3 (e.g., 1, 2, 3) gas-solid separation domes, and the deep polymerization reactor is provided with 2-6 (e.g., 3, 4, 5) zones, and a catalyst modifier injection nozzle is provided in any one zone or in each zone for feeding the catalyst modifier.

[0016] The position of the catalyst modifier injection nozzle is perpendicular to the material level in the deep polymerization reactor, and the position of the catalyst modifier injection nozzle avoids the position of the dome.

[0017] In this invention, the catalyst modifier injection nozzle can be set in any one zone or in each zone. If the injection nozzle is set in the first zone, the catalyst modifier enters the deep polymerization reactor from the first zone, and its residence time in the reactor is longer, resulting in better technical effects. If the injection nozzle is set in other zones, the catalyst modifier enters the deep polymerization reactor from other zones, and the residence time of the catalyst modifier in the reactor can be flexibly controlled to a certain extent.

[0018] In some embodiments of the olefin polymerization method provided by the present invention, the number of stirring blades arranged along the stirring shaft in the deep polymerization reactor is 5-60 (e.g., 6, 10, 15, 20, 25, 30, 35, 40, 45, 50).

[0019] In some implementations, the agitator blades are T-shaped agitators.

[0020] In this invention, the deep polymerization reactor can be a specially designed horizontal stirred reactor with a catalyst modifier inlet (injection nozzle). It can be considered a plug flow reactor, providing a temperature- and pressure-controlled polymerization reaction environment. The residence time of the catalyst modifier material can be 1s-10h (e.g., 10s, 20s, 30s, 1min, 5min, 10min, 20min, 30min, 1h, 2h, 3h, 5h, 8h), allowing the reactants to continue the deep polymerization reaction; wherein:

[0021] The length-to-diameter ratio of the deep polymerization reactor can be controlled between 2 and 15; the design pressure of the deep polymerization reactor is set to 1.1 to 1.2 times the pressure under normal operating conditions; several agitator blade groups are set in the deep polymerization reactor; the agitator blades in the agitator blade groups can be T-shaped agitators; the phase stagger angle of the agitator blade groups is determined according to the reactor diameter D. For example, when D < 500 mm, the phase of the agitator blade group is staggered by 90° from the phase of the next agitator blade group along the axis; when 500 mm < D < 2000 mm, four agitator blade groups are selected and the phase of each agitator blade group is staggered by 60° from the phase of the next agitator blade group along the axis; when D > 2000 mm, the phase of the agitator blade group is staggered by 45° from the phase of the next agitator blade group along the axis; to prevent polymer agglomeration, the material level in the deep polymerization reactor can be controlled between 65% and 70%.

[0022] To ensure that measuring elements such as thermometers and pressure gauges can work properly, the instrument ports should be arranged perpendicular to the material level and above the reactor shell.

[0023] According to the olefin polymerization method provided by the present invention, in some embodiments, the polymerization process of the coordination polymerization reaction in step (1) is selected from one or more of gas phase polymerization process, slurry polymerization process and slurry-gas phase combined process.

[0024] In some implementations, the polymerization reactor for the coordination polymerization reaction in step (1) is a single polymerization reactor, or multiple polymerization reactors connected in series, or a prepolymerization reactor connected in series with a single polymerization reactor, or a prepolymerization reactor connected in series with multiple polymerization reactors.

[0025] According to the olefin polymerization method provided by the present invention, in some embodiments, the polymerization reactor in step (1) is a first polymerization reactor #1 connected in series with a second polymerization reactor #2, or a prepolymerization reactor connected in series with the first polymerization reactor #1 and the first polymerization reactor #1 connected in series with the second polymerization reactor #2; and,

[0026] A deep polymerization reactor #3 is connected in series at the end of the second polymerization reactor #2.

[0027] According to the present invention, for example, during the polymerization process, a first polymerization reactor #1 is connected in series with or without a prepolymerization reactor to carry out a normal olefin polymerization reaction; a second polymerization reactor #2 is connected in series with or without a second polymerization reactor to carry out a normal olefin polymerization reaction; a specially designed deep polymerization reactor #3 is connected in series at the end of the first polymerization reactor, and a certain amount of catalyst modifier is added to the deep polymerization reactor #3 to quickly eliminate hydrogen in the reaction system, so that the monomers can continue to polymerize under hydrogen-free or near-hydrogen-free conditions to generate higher molecular weight components; the material from the deep polymerization reactor #3 can be subjected to subsequent flash evaporation or separation, extrusion granulation and other processes to produce polyolefin resin products.

[0028] According to the present invention, the prepolymerization reactor can be a common stirred tank reactor, loop reactor, or gas-phase fluidized bed, etc.

[0029] The polymerization method according to the present invention further includes a prepolymerization step: in a prepolymerization reactor, propylene monomer undergoes a prepolymerization reaction in the presence of a catalyst. The operating steps and process conditions of the prepolymerization reaction can be conventional choices in the art, and will not be described in detail here.

[0030] According to the present invention, the first polymerization reactor #1 can be a common olefin polymerization reactor such as a loop slurry reactor, a gas-phase fluidized bed reactor, a vertical stirred tank with mechanical stirring, or a horizontal stirred tank.

[0031] According to the present invention, the second polymerization reactor #2 may be the same as or different from the first polymerization reactor #1.

[0032] In some embodiments of the olefin polymerization method provided by the present invention, the olefin monomer is propylene.

[0033] In some embodiments, the comonomer is an α-olefin, preferably selected from one or more of ethylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-nonene, and 1-decene.

[0034] According to the olefin polymerization method provided by the present invention, in some embodiments, the effluent material from the polymerization reactor in step (1) is still reactive, comprising: polyolefin powder generated in the preceding polymerization reactor, unreacted monomers, hydrogen, polymerization catalyst, inert gas (such as nitrogen) and other small amounts of saturated alkanes.

[0035] In some embodiments of the olefin polymerization method provided by the present invention, the catalyst modifier is a mixture of organometallic compounds and alkylaluminum compounds;

[0036] The general formula of the organometallic compound is R(R')-MX(X'), where:

[0037] R and R' are each independently cyclopentadienyl, indene, or fluorenyl without or with substituents, wherein the substituents are preferably selected from methyl, ethyl, propyl, butyl, or cycloalkyl.

[0038] M is a transition metal element, preferably selected from Fe, Ti, Cr, and Mn;

[0039] X and X' are each independently a halogen atom, an alkyl group, or an alkoxy group.

[0040] In some embodiments, the organometallic compound is selected from one or more of bis(cyclopentadienyl)titanium chloride, bis(cyclopentadienyl)methoxytitanium chloride, bis(cyclopentadienyl)ethoxytitanium chloride, and bis(cyclopentadienyl)phenoxytitanium chloride.

[0041] In some embodiments, the alkylaluminum compound is selected from one or more of trimethylaluminum, triethylaluminum, tributylaluminum, triisobutylaluminum, trihexylaluminum, trioctylaluminum, tridecylaluminum, dimethylaluminum chloride, diethylaluminum chloride, dibutylaluminum chloride, and diisobutylaluminum chloride, more preferably triethylaluminum.

[0042] In some embodiments, the molar ratio of the organometallic compound to the alkylaluminum compound is 1:1 to 1:10 (e.g., 1:2, 1:5, 1:6, 1:7, 1:8, 1:9), preferably 1:6 to 1:10.

[0043] In some embodiments, the molar ratio of the catalyst modifier to the initial total amount of hydrogen in the system ranges from 1 / 100 to 1 / 100000, for example, 1 / 200, 1 / 500, 1 / 1000, 1 / 2000, 1 / 4000, 1 / 5000, 1 / 8000, 1 / 10000, 1 / 20000, 1 / 40000, 1 / 50000, 1 / 60000, 1 / 80000.

[0044] Here, “initial total hydrogen in the system” can be understood as: the initial total hydrogen in the material system entering the deep polymerization reactor, or the residual total hydrogen in the material at the outlet of the polymerization reactor described in step (1).

[0045] According to the olefin polymerization method provided by the present invention, the coordination polymerization reaction time in step (1) can be in the range of 0.5-2h, for example, 1h or 1.5h. The deep polymerization reaction time in step (2) can be in the range of 0.1-2h, for example, 0.2h, 0.3h, 0.4h, 0.5h, 1h or 1.5h.

[0046] According to the olefin polymerization method provided by the present invention, in some embodiments, the mechanical properties of the obtained polyolefin resin product are improved by 10% or more, for example, 12%, 15%, or 20%.

[0047] In some embodiments, the efficiency of the polymerization catalyst is improved by 1%-30%, for example, 2%, 4%, 5%, 6%, 8%, 10%, 12%, 15%, 16%, 18%, 20%, and 25%.

[0048] In some embodiments, the content of ultra-high molecular weight components with a molecular weight ≥ 7 million in the polyolefin is 0.1wt%-30wt%, for example, 0.2wt%, 0.4wt%, 0.5wt%, 0.8wt%, 1.0wt%, 2.0wt%, 4.0wt%, 5.0wt%, 6.0wt%, 8.0wt%, 10wt%, 15wt%, 20wt%, and 25wt%. The polyolefin obtained by the polymerization method of the present invention can be polypropylene, for example, propylene homopolymer or propylene copolymer.

[0049] The polymerization catalysts used in the olefin polymerization or copolymerization of this invention include, but are not limited to, Ziegler-Natta (ZN) catalysts and metallocene catalysts.

[0050] Ziegler-Natta type catalysts typically include: (a) an active solid catalyst component, preferably a titanium-containing solid catalyst active component; (b) an organoaluminum compound (co-catalyst component); and optionally, (3) an external electron donor component.

[0051] Available active solid catalyst components include commercially available SUG catalysts, SAL catalysts, CDi catalysts, P100 catalysts, etc.

[0052] The organoaluminum compound used as a cocatalyst component is preferably an alkylaluminum compound, more preferably a trialkylaluminum compound, such as triethylaluminum, triisobutylaluminum, tri-n-butylaluminum, etc.

[0053] The ratio of the active solid catalyst component to the organoaluminum compound, in terms of the Ti / Al molar ratio, is 1:5 to 1:400 (e.g., 1:10, 1:50, 1:120, 1:200, 1:300), preferably 1:25 to 1:100.

[0054] The compound that serves as the external electron donor component can be any type of electron-donating compound, including but not limited to alkoxy-substituted silanes, whose general formula can be SiRn(OR'). 4-n In the formula:

[0055] 0 < n ≤ 3,

[0056] R and R' may be the same or different, and each is independently selected from alkyl, cycloalkyl, aryl, haloalkyl, etc. R can also be a halogen or a hydrogen atom. Specifically, it may include, but is not limited to, tetramethoxysilane, tetraethoxysilane, trimethylmethoxysilane, trimethylethoxysilane, trimethylphenoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, methyl tert-butyldimethoxysilane, methyl isopropyldimethoxysilane, diphenoxydimethoxysilane, diphenyldiethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, vinyltrimethoxysilane, methylcyclohexyldimethoxysilane, ethylcyclohexyldimethoxysilane, di-n-propyldimethoxysilane, diisopropyldimethoxysilane, di-n-butyldimethoxysilane, diisobutyl... Di(di-dimethoxysilane), bis(tert-butyldimethoxysilane), cyclopentyltrimethoxysilane, isopropyltrimethoxysilane, n-propyltrimethoxysilane, n-propyltriethoxysilane, ethyltriethoxysilane, cyclohexylpyrrolidinedimethoxysilane, bis(pyrrolidine)-dimethoxysilane, bis(perhydroisoquinoline)dimethoxysilane, 2-ethylpiperidinyl-2-tert-butyldimethoxysilane, (1,1,1-trifluoro-2-propyl)-2-ethylpiperidinyldimethoxysilane, and (1,1,1-trifluoro-2-propyl)-methyldimethoxysilane, etc.

[0057] The amount of external electron donor component can be selected according to conventional methods in this field, and will not be elaborated here.

[0058] The metallocene catalysts used in this invention typically include: (a) an active catalyst component, preferably a catalyst active component containing titanium, zirconium, or hafnium; (b) an organoaluminum compound (co-catalyst component ii); and optionally, (3) a boron salt compound.

[0059] In some embodiments, the metallocene catalyst comprises: a support, a metallocene coordination compound, and a co-catalyst; wherein:

[0060] The carrier can be selected from particulate silica or layered silicates.

[0061] The metallocene coordination compound can be selected from bridged C2-symmetrical compounds containing a group IV metal and an indenyl group, such as, but not limited to, rac-dimethylsilyl-bis(2-methyl-4-phenylindenyl)zirconia, rac-dimethylsilyl-bis[2-methyl-4-(4'-tert-butylphenyl)indenyl]zirconia, rac-methyl(cyclohexyl)silyl-bis[2-methyl-4-(4'-tert-butylphenyl)indenyl]zirconia, rac-dimethylsilyl-bis(2-methyl-4-carbazolylindenyl)zirconia, rac-dimethylsilyl-bis[2-methyl-4-(3,5-di-tert-butylphenyl)-7-methoxyindenyl]zirconia, rac-dimethylsilyl-bis[2-methyl-4-phenyl-5-methoxy-6-dimethylsilyl]zirconia, etc. One or more of the following: rac-dimethylsilyl-bis(2-isopropyl-4-phenylindyl)zirconia, rac-dimethylsilyl-bis[2-isopropyl-4-(4'-tert-butylphenyl)indyl]zirconia, rac-methyl(cyclohexyl)silyl-bis[2-isopropyl-4-(4'-tert-butylphenyl)indyl]zirconia, rac-dimethylsilyl-bis(2-isopropyl-4-carbazolylindyl)zirconia, rac-dimethylsilyl-bis[2-isopropyl-4-(3,5-di-tert-butylphenyl)-7-methoxyindyl]zirconia, rac-dimethylsilyl-bis[2-isopropyl-4-phenyl-5-methoxy-6-tert-butylindyl]zirconia, and compounds thereof with alkyl-substituted chlorine.

[0062] The co-catalyst ii can be selected from methylaluminoxane or modified methylaluminoxane.

[0063] In some embodiments, the active component of the metallocene catalyst includes an active support and a metallocene coordination compound as described above; wherein, the active support refers to silica, aluminosilicate, or layered silicate modified by sulfation, fluorination, or chlorination.

[0064] For example, the metallocene catalyst comprises silica, a metallocene coordination compound, and methylaluminoxane; wherein the metallocene coordination compound is selected from rac-dimethylsilyl-bis(2-methyl-4-phenylindene)zirconia dichloride, rac-dimethylsilyl-bis[2-methyl-4-(4'-tert-butylphenyl)indene]zirconia dichloride, rac-methyl(cyclohexyl)silyl-bis[2-methyl-4-(4'-tert-butylphenyl)indene]zirconia dichloride, rac-dimethylsilyl-bis(2-methyl-4-carbazoleindene)zirconia dichloride, rac-dimethylsilyl-bis[2-methyl-4-(3,5-di-tert-butylphenyl)-7-methoxyindene]zirconia dichloride, rac-dimethylsilyl-bis[2-methyl-4-phenyl-5-methoxy-6-methoxyindene]zirconia dichloride, and rac-dimethylsilyl-bis[2-methyl-4-phenyl-5-methoxy-6-methoxyindene]. One or more of the following: rac-dimethylsilyl-bis(2-isopropyl-4-phenylindyl)zirconia, rac-dimethylsilyl-bis[2-isopropyl-4-(4'-tert-butylphenyl)indyl]zirconia, rac-methyl(cyclohexyl)silyl-bis[2-isopropyl-4-(4'-tert-butylphenyl)indyl]zirconia, rac-dimethylsilyl-bis(2-isopropyl-4-carbazolylindyl)zirconia, rac-dimethylsilyl-bis[2-isopropyl-4-(3,5-di-tert-butylphenyl)-7-methoxyindyl]zirconia, rac-dimethylsilyl-bis[2-isopropyl-4-phenyl-5-methoxy-6-tert-butylindyl]zirconia, and compounds thereof with alkyl-substituted chlorine.

[0065] The proportions of each component in the metallocene catalyst can be conventionally chosen in the field and will not be elaborated here.

[0066] In a second aspect, a polyolefin prepared by the olefin polymerization method described above is provided, wherein the polyolefin contains an ultra-high molecular weight component with a molecular weight ≥ 7 million, and the content of the ultra-high molecular weight component is 0.1 wt%-30 wt%, preferably 1 wt%-10 wt%.

[0067] In some embodiments, the melt index of the polyolefin under a load of 2.16 kg and a temperature of 230 °C can be 0.1-50 g / 10 min, for example, 0.2 g / 10 min, 0.5 g / 10 min, 1.0 g / 10 min, 2.0 g / 10 min, 3.0 g / 10 min, 4.0 g / 10 min, 5.0 g / 10 min, 6.0 g / 10 min, 8.0 g / 10 min, 10 g / 10 min, 12 g / 10 min, 14 g / 10 min, 15 g / 10 min, 20 g / 10 min, 25 g / 10 min, 30 g / 10 min, 35 g / 10 min, 40 g / 10 min, and 45 g / 10 min.

[0068] In some embodiments, the polyolefin may be polypropylene, for example, homopolymer polypropylene or copolymer polypropylene.

[0069] This invention creatively proposes introducing the material emanating from the end-stage polymerization reactor into a specially designed horizontal deep polymerization reactor before gas-solid or gas-liquid-solid separation. Simultaneously, a catalyst modifier is added to this horizontal deep polymerization reactor to continue the polymerization reaction. This catalyst modifier efficiently and rapidly catalyzes the reaction between olefins and hydrogen, thereby removing hydrogen from the system. This allows the monomers in the material to continue deep polymerization under hydrogen-free or near-hydrogen-free conditions, generating components with higher molecular weights and improving the performance of polyolefin products. Furthermore, by designing and controlling the structure of this horizontal deep polymerization reactor, the residence time (or deep polymerization time) of the material in the reactor can be controlled to adjust the production load (adjustable from 1% to 30%), thereby improving the efficiency of the catalyst in the system. Moreover, by designing and arranging the agitator blades of the deep polymerization reactor, the distribution of the catalyst modifier and the system material is influenced, thereby affecting the uniformity of the polyolefin resin product distribution and improving the uniformity of polymer powder particle size distribution.

[0070] Compared with the prior art, the beneficial effects of the technical solution of the present invention are at least as follows:

[0071] The method of this invention ingeniously and fully utilizes the principle of olefin coordination polymerization. Based on the normal chain initiation, chain propagation, chain transfer, and chain termination reactions, a certain amount of catalyst modifier is added to the reactants in the deep polymerization reactor by adding a deep polymerization reactor at the end of the polymerization reactor. Combined with the design of the structure and layout of the stirring blade assembly in the deep polymerization reactor, hydrogen elimination and deep chain propagation reaction steps are added to the normal olefin polymerization process. This allows the still reactive materials to continue deep polymerization, which not only yields polyolefin products containing higher molecular weight components and comprehensively improves the performance of polyolefin products (the mechanical properties of polyolefin products are improved, and the uniformity of particle size distribution of the resulting powder is also improved), but also allows for the additional utilization of 1%-30% of the catalyst efficiency, avoiding resource waste and reducing production costs. Attached Figure Description

[0072] Figure 1 Schematic diagrams of the polymerization process flow for some implementation schemes;

[0073] Figure 2 A schematic diagram showing the partitioning of the deep polymerization reactor and the arrangement of the catalyst modifier injection nozzles is shown.

[0074] Figure 3(a) shows a side view of the catalyst modifier injection nozzle of the deep polymerization reactor;

[0075] Figure 3(b) shows a front view of the catalyst modifier injection nozzle of the deep polymerization reactor;

[0076] Figure 4 A schematic diagram of the arrangement of the stirring blades in a deep polymerization reactor is shown.

[0077] Figure 5 shows a schematic diagram of the arrangement of catalyst modifier injection nozzles N1 to N5 and dome inlet N6;

[0078] Figure 6(a) shows a schematic diagram of the phase distribution of the stirring blade assembly;

[0079] Figure 6(b) shows a schematic diagram of the arrangement of the stirring blades in the deep polymerization reactor. Detailed Implementation

[0080] To provide a detailed understanding of the technical features and content of this invention, preferred embodiments will be described in more detail below. While preferred embodiments are described in the examples, it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer shall apply. Unless otherwise specified, the raw materials used in the examples are commercially available.

[0081] In this invention, such as Figure 1 As shown, the polymerization reactor can be configured as follows: a prepolymerization reactor is connected in series with polymerization reactor #1, then in series with polymerization reactor #2, and finally, a deep polymerization reactor #3 is connected in series at the end of polymerization reactor #2. A catalyst modifier is added to the deep polymerization reactor #3, allowing the product system exiting polymerization reactor #2 to enter the deep polymerization reactor #3 for further deep polymerization, producing higher molecular weight components and improving both the final product performance and catalyst efficiency. A catalyst modifier may or may not be added to polymerization reactor #2; however, if it is necessary to control the content of ultra-high molecular weight components within a higher range, a catalyst modifier can be added to polymerization reactor #2.

[0082] In this invention, a series deep polymerization reactor #3 is designed at the end of the polymerization reactor in step (1). The purpose is to increase the molecular weight of the polymer by adding a catalyst modifier to prolong the polymerization time, thereby improving the mechanical strength of the polymer and the efficiency of the catalyst. The reactor volume is calculated based on a residence time of 30 minutes, and the length-to-diameter ratio of each reactor can be 2 to 15.

[0083] In this invention, the deep polymerization reactor #3 can be a horizontal stirred reactor or a vertical stirred reactor; in order to reduce axial backmixing of products, raw materials and catalysts at different times and increase radial backmixing, and to ensure the horizontal plug flow of materials, a horizontal stirred reactor (i.e., a horizontal deep polymerization reactor #3) is preferred; the horizontal stirred reactor #3 can be designed with one or more gas-solid separation domes.

[0084] In this invention, multiple zones are set in the deep polymerization reactor #3. One or more catalyst modifier injection nozzles can be set in any zone or in each zone for feeding the catalyst modifier, such as... Figure 2 As shown. The time for deep polymerization can be controlled by adjusting the addition position of the catalyst modifier. The position of the catalyst modifier injection nozzle can be perpendicular to the material level surface, and the nozzle position should avoid the dome position, such as... Figure 3(a) and 3(b) As shown.

[0085] In this invention, the deep polymerization reactor #3 has radial temperature gradients, propylene concentration gradients, and catalyst concentration gradients. These differences can lead to localized temperature runaway, agglomeration, and uneven product properties within the bed. Therefore, effective mixing and stirring are particularly important.

[0086] In this invention, the stirring blades of the deep polymerization reactor #3 can be T-type or other agitators that enhance radial mixing. The selection of the agitator should meet the requirements of avoiding powder sticking to the walls and reducing axial backmixing, allowing polymer particles to move in a near-plug flow within the reactor. The deep polymerization reactor #3 has one stirring shaft and several stirring blades; two blades are arranged at 180° on the same phase of the stirring shaft, referred to as a stirring blade group; the phase of each stirring blade group is staggered from the phase of the next stirring blade group along the shaft, ensuring that the powder has a forward driving force to convey the powder. For example, the staggered angle distribution of the stirring blade groups is 90°, 60°, and 45°, such as... Figure 4 As shown; the specific offset angle is determined based on the reactor volume, reaction residence time, and reaction conditions.

[0087] Specifically, taking a 450,000-ton-per-year gas-phase polypropylene industrial production unit as an example, step (2) selects a horizontal deep polymerization reactor #3, wherein:

[0088] To ensure that the residence time of polypropylene particles in the horizontal deep polymerization reactor #3 meets the requirement of 1 hour, the effective volume of the horizontal deep polymerization reactor #3 should be greater than 70 m³. 3 The reactor is 16.8m long and 3m in diameter, with an aspect ratio of approximately 5.6. Based on the length of this horizontal deep polymerization reactor #3, the reactor is divided into 5 zones. Due to the low catalyst activity in the system within this horizontal deep polymerization reactor #3, it is necessary to increase the propylene space velocity to increase reaction efficiency in order to ensure the yield of high molecular weight polypropylene. Under conditions of high space velocity and low conversion rate, in order to prevent polypropylene particles from being entrained in the propylene recovery system and clogging the equipment, a gas-solid separation dome is added in the fourth zone.

[0089] One or more catalyst modifier injection nozzles can be set in any zone, or catalyst modifier injection nozzles (N1 to N5) can be set in each zone for catalyst modifier feeding. The position of the catalyst modifier injection nozzle is perpendicular to the material level surface. Among them, the position of injection nozzle N4 should avoid the position of the dome. The arrangement of injection nozzles N1 to N5 and dome port N6 is shown in Figure 5(a) and Figure 5(b).

[0090] The horizontal deep polymerization reactor #3 can be equipped with 45 T-shaped stirring blade groups, each group consisting of 2 T-shaped blades arranged at 180° angles to each other. The 45 T-shaped stirring blade groups are divided into four phases: A, B, C, and D. Each stirring blade phase is staggered from the next stirring blade group along the axis. The stirring blade phase angles and stirring blade arrangement are shown in Figures 6(a) and 6(b).

[0091] To reduce the temperature gradient, propylene concentration gradient, and catalyst concentration gradient within the horizontal deep polymerization reactor #3, the agitator should have a wall-scraping effect. Radial backmixing can eliminate hot spots and prevent polypropylene from agglomerating or experiencing localized overheating. Therefore, the distance between each agitator blade and the reactor body should be as small as possible, not exceeding 10 mm. The agitator blades should be in close contact with each other axially without any gaps.

[0092] Stable operation of the prepolymerization reactor, the first polymerization reactor #1, and the second polymerization reactor #2 may include temperature control, pressure control, and propylene partial pressure control. The temperature range, pressure range, and propylene partial pressure range of the polymerization reaction are all conventional choices in the field and will not be elaborated here.

[0093] Stable operation of the horizontal deep polymerization reactor #3 can include temperature control, pressure control, and propylene partial pressure control.

[0094] Temperature control is crucial because the reaction in the horizontal deep polymerization reactor #3 is relatively weak. During the initial start-up phase, heat needs to be supplied to the reactor to ensure rapid attainment of reaction conditions. However, the heat generated during normal deep polymerization needs to be removed by the vaporization of liquid propylene. Therefore, a jacket is installed on the horizontal deep polymerization reactor, employing a stratified control system of hot water and propylene rapid cooling. When the reactor temperature is below 60°C, the temperature control switches to hot water heating; when the reactor temperature is above 60°C, the temperature control switches to propylene rapid cooling control, with the amount of propylene used for rapid cooling determined based on the amount of heat released. The reaction temperature can be, for example, within the range of 50-70°C.

[0095] Pressure control in the horizontal deep polymerization reactor #3 is divided into three levels. Under normal operating conditions, when the pressure in the horizontal deep polymerization reactor #3 is between 2.0-2.3 MPa, the pressure is controlled by increasing or decreasing the circulating propylene discharge. If the pressure still cannot be controlled, it is necessary to consider adjusting the circulating water flow to increase or decrease the propylene condensation rate to control the pressure. When the pressure exceeds 2.5 MPa, interlocking is used to control the pressure by directly discharging circulating propylene. The reaction pressure, for example, can be between 2.0-2.5 MPa.

[0096] Propylene partial pressure control is crucial because the presence of inert components reduces reaction efficiency. Simply reducing propylene consumption will decrease reaction efficiency, increase equipment size, and increase energy consumption. Experiments have shown that the propylene content in the circulating propylene should be controlled between 85% and 90 mol%. Therefore, online chromatography is used to analyze the propylene content in the circulating gas to control tail gas emissions.

[0097] In all the embodiments and comparative examples, the active component of the Ziegler-Natta (ZN) catalyst used was mineral oil as a diluent, with a solid content of 30 wt%; wherein, the mass content of titanium was 1-4%, the mass content of magnesium was 10-20%, and the mass content of internal electron donor was 10-20%.

[0098] In the various embodiments and comparative examples, the active component of the metallocene catalyst used was: rac-dimethylsilyl-bis(2-methyl-4-phenylindenyl)zirconium dichloride, with a mass content of 0.1-2%, and silica gel support, with a mass content of 60-40%. The co-catalyst component ii of the metallocene catalyst was an organoaluminum compound methylaluminoxane (MAO), with a mass content of 10-60%, and its Al / Zr molar ratio was controlled to be 100.

[0099] In each embodiment and comparative example, the preparation steps of the catalyst modifier used are as follows: under a nitrogen atmosphere, 1 mol of titanium dichlorodecene is taken, and triethylaluminum is weighed according to the molar ratio of titanium dichlorodecene to triethylaluminum of 1:6. Titanium dichlorodecene and triethylaluminum are dissolved in 6 L of n-hexane solution, and the mixture is left at room temperature for at least 24 hours to obtain the catalyst modifier.

[0100] In all embodiments and comparative examples, the test methods for each performance index of the product can be carried out with reference to national standards, and will not be repeated here.

[0101] The following embodiments and comparative examples, using actual large-scale industrial-grade polypropylene plant production as an example, simulate the process flow of the polymerization method using process simulation software. Because the flow pattern of the gas-phase horizontal reactor is approximately plug flow, with a narrow residence time distribution, a plug flow model is selected for the reactor, and the polymerization reaction kinetic equations are calculated based on the reaction mechanism, choosing coordination polymerization for simulation.

[0102] Example 1:

[0103] Taking a large-scale horizontal gas-phase polypropylene unit as an example, a full-process model is performed, using Zn catalyst to produce propylene homopolymer. The reaction unit consists of three reactors connected in series: the first polymerization reactor #1 and the second polymerization reactor #2 are connected in series, and the end of the second polymerization reactor #2 is connected in series with a horizontal deep polymerization reactor #3. In the first polymerization reactor #1 and the second polymerization reactor #2, propylene monomers undergo polymerization in the presence of catalyst and hydrogen. Before the material from the outlet of the second polymerization reactor #2 undergoes gas-solid separation or gas-liquid-solid separation, it is introduced into the horizontal deep polymerization reactor #3, and a catalyst modifier is added to it to quickly eliminate chain transfer agents in the reactant system, allowing the reactants in the material to continue the deep polymerization reaction, producing ultra-high molecular weight components, and obtaining propylene homopolymer.

[0104] in,

[0105] The feed rates of the active catalyst component in the first polymerization reactor #1 are 1.27 kg / h, the feed rates of the co-catalyst component AlEt3 are 4.52 kg / h, the feed rates of the external electron donor diisobutyldimethoxysilane (DIBDMS, B-donor) are 0.67 kg / h, the feed rate of propylene is 46.2 t / h, and the feed rate of hydrogen is 0.9 kg / h; the output of the first polymerization reactor #1 is 41.7 t / h.

[0106] The propylene feed rate of the second polymerization reactor #2 is 23.1 t / h, the hydrogen feed rate is 0.45 kg / h, and the output of the second polymerization reactor #2 is 20.8 t / h.

[0107] The overall molar ratio of the polymerization catalyst was controlled to be Al / Si = 12, and the molar ratio of Al / Mg = 4.

[0108] The reaction time for both the first polymerization reactor #1 and the second polymerization reactor #2 is 1 hour.

[0109] The feed rate of catalyst modifier to the horizontal deep polymerization reactor #3 is 10 g / h, the material residence time is 30 min, and the output of the horizontal deep polymerization reactor #3 is 6.9 t / h. The horizontal deep polymerization reactor #3 has a length-to-diameter ratio of 5.6. It is designed with a gas-solid separation dome and five zones. The first zone has one catalyst modifier injection nozzle for feeding the catalyst modifier. The position of the catalyst modifier injection nozzle is perpendicular to the material level surface and avoids the dome. The horizontal deep polymerization reactor #3 is equipped with... 45 sets of T-shaped The agitator blades are arranged in groups, with two blades in each group arranged at 180°. The phase of each group of agitator blades is staggered by 90° from the phase of the next group of agitator blades along the axis. The blade width is 300mm.

[0110] The polymerization temperature is 60-70℃ and the pressure is 2.0-2.3MPa; the production load of the unit is 69.4t / h.

[0111] The polymer powder obtained from the first polymerization reactor #1 and the polymer powder obtained from the second polymerization reactor #2 both have an MFR of 3.0 g / 10 min, a weight-average molecular weight of Mw = 352699, and a molecular weight distribution width of MWD = 4.9.

[0112] The polymer powder prepared by the horizontal deep polymerization reactor #3 has an MFR of 1.7 g / 10 min, a weight-average molecular weight of Mw = 494868, and a molecular weight distribution width of MWD = 6.7.

[0113] Example 2:

[0114] Taking a large-scale horizontal gas-phase polypropylene unit as an example, a full-process model is performed, using Zn catalyst to produce propylene-ethylene random copolymers. The reaction unit consists of three reactors connected in series: the first polymerization reactor #1 and the second polymerization reactor #2 are connected in series, and the end of the second polymerization reactor #2 is connected in series with a horizontal deep polymerization reactor #3. In the first polymerization reactor #1 and the second polymerization reactor #2, propylene monomers and ethylene undergo copolymerization in the presence of catalyst and hydrogen. Before the material from the outlet of the second polymerization reactor #2 undergoes gas-solid separation or gas-liquid-solid separation, it is introduced into the horizontal deep polymerization reactor #3, and a catalyst modifier is added to it to quickly eliminate chain transfer agents in the reactant system, allowing the reactants in the material to continue the deep polymerization reaction, producing ultra-high molecular weight components, and obtaining propylene-ethylene random copolymers.

[0115] in,

[0116] The feed rates of the active catalyst component in the first polymerization reactor #1 are 0.99 kg / h, the feed rates of the co-catalyst component AlEt3 are 8.84 kg / h, the feed rates of the external electron donor diisopropyl dimethoxysilane (DIPDMS, P-donor) are 5.27 kg / h, the feed rates of propylene are 40.2 t / h, the feed rates of ethylene are 1.63 t / h, and the feed rates of hydrogen are 1.0 kg / h; the output of the first polymerization reactor #1 is 37.5 t / h.

[0117] The second polymerization reactor #2 has a propylene feed rate of 16.5 t / h, an ethylene feed rate of 8.43 t / h, a hydrogen feed rate of 1.1 kg / h, and a production capacity of 18.7 t / h.

[0118] The overall molar ratio of the polymerization catalyst was controlled to Al / Si = 3, and the molar ratio of Al / Mg = 10.

[0119] The reaction time for both the first polymerization reactor #1 and the second polymerization reactor #2 is 1 hour.

[0120] The feed rate of catalyst modifier to the horizontal deep polymerization reactor #3 is 10 g / h, the material residence time is 30 min, and the output of the horizontal deep polymerization reactor #3 is 6.2 t / h. The horizontal deep polymerization reactor #3 has a length-to-diameter ratio of 5.6. It is designed with a gas-solid separation dome and five zones. The first zone has one catalyst modifier injection nozzle for feeding the catalyst modifier. The position of the catalyst modifier injection nozzle is perpendicular to the material level surface and avoids the dome. The horizontal deep polymerization reactor #3 is equipped with... 45 sets of T-shaped The agitator blades are arranged in groups, with two blades in each group arranged at 180°. The phase of each group of agitator blades is staggered by 90° from the phase of the next group of agitator blades along the axis. The blade width is 300mm.

[0121] The polymerization temperature is 60-70℃ and the pressure is 2.0-2.3MPa; the production load of the unit is 62.4t / h.

[0122] The polymer powder obtained from the first polymerization reactor #1 and the polymer powder obtained from the second polymerization reactor #2 both have an MFR of 1.5 g / 10 min, a weight-average molecular weight of Mw = 45317.6, a molecular weight distribution width of MWD = 5.0, and a total ethylene content of 4.3 wt%.

[0123] The polymer powder obtained from the horizontal deep polymerization reactor #3 has an MFR of 0.8 g / 10 min, a weight-average molecular weight of Mw = 1244576, a molecular weight distribution width of MWD = 10.1, and a total ethylene content of 5.4 wt%.

[0124] Example 3:

[0125] Taking a large-scale horizontal gas-phase polypropylene unit as an example, a full-process model is performed, using Zn catalyst to produce propylene-ethylene impact copolymer; the reaction unit consists of three reactors connected in series: the first polymerization reactor #1 and the second polymerization reactor #2 are connected in series, and the end of the second polymerization reactor #2 is connected in series with a horizontal deep polymerization reactor #3; in the first polymerization reactor #1 and the second polymerization reactor #2, propylene monomers polymerize and propylene monomers copolymerize with ethylene in the presence of catalyst and hydrogen; before the material from the outlet of the second polymerization reactor #2 undergoes gas-solid separation or gas-liquid-solid separation, it is introduced into the horizontal deep polymerization reactor #3, and a catalyst modifier is added to it to quickly eliminate chain transfer agents in the reactant system, so that the reactants in the material continue to undergo deep polymerization reaction, producing ultra-high molecular weight components, and obtaining propylene-ethylene impact copolymer;

[0126] in,

[0127] The feed rates of the active catalyst component in the first polymerization reactor #1 are 1.71 kg / h, the feed rates of the co-catalyst component AlEt3 are 6.09 kg / h, the feed rates of the external electron donor diisopropyl dimethoxysilane (DIPDMS, P-donor) are 1.57 kg / h, the feed rate of propylene is 44.7 t / h, and the feed rate of hydrogen is 10.5 kg / h; the output of the first polymerization reactor #1 is 39.8 t / h.

[0128] The second polymerization reactor #2 has a propylene feed rate of 4.4 t / h, an ethylene feed rate of 4.7 t / h, a hydrogen feed rate of 2.7 kg / h, and a production capacity of 7.8 t / h.

[0129] The overall molar ratio of the polymerization catalyst was controlled to be Al / Si = 6, and the molar ratio of Al / Mg = 4.

[0130] The reaction time for both the first polymerization reactor #1 and the second polymerization reactor #2 is 1 hour.

[0131] The feed rate of catalyst modifier to the horizontal deep polymerization reactor #3 is 10 g / h, the material residence time is 30 min, and the output of the horizontal deep polymerization reactor #3 is 3.9 t / h. The horizontal deep polymerization reactor #3 has a length-to-diameter ratio of 5.6. It is designed with a gas-solid separation dome and five zones. The first zone has one catalyst modifier injection nozzle for feeding the catalyst modifier. The position of the catalyst modifier injection nozzle is perpendicular to the material level surface and avoids the dome. The horizontal deep polymerization reactor #3 is equipped with... 45 sets of T-shaped The agitator blades are arranged in groups, with two blades in each group arranged at 180°. The phase of each group of agitator blades is staggered by 90° from the phase of the next group of agitator blades along the axis. The blade width is 300mm.

[0132] The polymerization temperature is 60-70℃, the pressure is 2.0-2.3MPa, and the production load of the unit is 51.5t / h.

[0133] The polymer powder obtained from the first polymerization reactor #1 has an MFR of 37.8 g / 10 min, and the polymer powder obtained from the second polymerization reactor #2 has an MFR of 20 g / 10 min. The polymer powder obtained from the first polymerization reactor #1 has a weight-average molecular weight of Mw = 187210, and the polymer powder obtained from the second polymerization reactor #2 has a weight-average molecular weight of Mw = 225917. The molecular weight distribution width is MWD = 5.1, the total ethylene content is 9.1 wt%, and the ethylene content of the rubber segment is 56 wt%.

[0134] The polymer powder obtained from the horizontal deep polymerization reactor #3 has an MFR of 10.9 g / 10 min, a weight-average molecular weight of Mw = 744107, a molecular weight distribution width of MWD = 15.9, a total ethylene content of 11 wt%, and an ethylene content of 61 wt% in the rubber segment.

[0135] Example 4:

[0136] Taking a large-scale horizontal gas-phase polypropylene unit as an example, a full-process model is performed, using Zn catalyst to produce propylene homopolymer. The reaction device consists of a prepolymer reactor and three reactors connected in series: the prepolymer reactor is connected in series with the first polymerization reactor #1, the first polymerization reactor #1 is connected in series with the second polymerization reactor #2, and the end of the second polymerization reactor #2 is connected in series with a horizontal deep polymerization reactor #3. In the prepolymer reactor, propylene monomers undergo prepolymerization in the presence of a catalyst. In the first polymerization reactor #1 and the second polymerization reactor #2, propylene monomers undergo polymerization in the presence of a catalyst and hydrogen. Before the material from the outlet of the second polymerization reactor #2 undergoes gas-solid separation or gas-liquid-solid separation, it is introduced into the horizontal deep polymerization reactor #3, and a catalyst modifier is added to it to quickly eliminate chain transfer agents in the reactant system, allowing the reactants in the material to continue deep polymerization, producing ultra-high molecular weight components, and obtaining propylene homopolymer.

[0137] in,

[0138] The feed rate of the active catalyst component in the prepolymer reactor is 1.27 kg / h, the feed rate of the co-catalyst component AlEt3 is 4.52 kg / h, the feed rate of the external electron donor diisobutyldimethoxysilane (DIBDMS, B-donor) is 0.67 kg / h, and the feed rate of propylene is 10 t / h; the temperature of the prepolymer reactor is controlled at 15℃.

[0139] The first polymerization reactor #1 has a propylene feed rate of 16.2 t / h and a hydrogen feed rate of 0.9 kg / h, resulting in a production capacity of 41.7 t / h.

[0140] The propylene feed rate in the second polymerization reactor #2 is 23.1 t / h, the hydrogen feed rate is 0.45 kg / h, and the output of the second polymerization reactor #2 is 20.8 t / h.

[0141] The overall molar ratio of the polymerization catalyst was controlled to be Al / Si = 12, and the molar ratio of Al / Mg = 4.

[0142] The reaction time for both the first polymerization reactor #1 and the second polymerization reactor #2 is 1 hour.

[0143] The feed rate of catalyst modifier to the horizontal deep polymerization reactor #3 is 10 g / h, the material residence time is 30 min, and the output of the horizontal deep polymerization reactor #3 is 6.9 t / h. The horizontal deep polymerization reactor #3 has a length-to-diameter ratio of 2.0. It does not have a gas-solid separation dome and is divided into two zones. The first zone has one catalyst modifier injection nozzle for feeding the catalyst modifier. The nozzle is positioned perpendicular to the material level and avoids the dome. The horizontal deep polymerization reactor #3 is equipped with... 45 sets of T-shapedThe agitator blades are arranged in groups, with two blades in each group arranged at 180°. The phase of each group of agitator blades is staggered by 90° from the phase of the next group of agitator blades along the axis. The blade width is 300mm.

[0144] The polymerization temperature is 60-70℃, the pressure is 2.0-2.3MPa, and the production load of the unit is 69.4t / h.

[0145] The polymer powder obtained from the first polymerization reactor #1 and the polymer powder obtained from the second polymerization reactor #2 both have an MFR of 3.0 g / 10 min, a weight-average molecular weight of Mw = 367931, and a molecular weight distribution width of MWD = 4.1.

[0146] The polymer powder prepared by the horizontal deep polymerization reactor #3 has an MFR of 1.5 g / 10 min, a weight-average molecular weight of Mw = 521167, and a molecular weight distribution width of MWD = 5.7.

[0147] Example 5

[0148] Taking a large-scale horizontal gas-phase polypropylene unit as an example, a full-process model is performed, using a metallocene catalyst to produce propylene homopolymer. The reaction unit consists of three reactors connected in series: the first polymerization reactor #1 and the second polymerization reactor #2 are connected in series, and the end of the second polymerization reactor #2 is connected in series with a horizontal deep polymerization reactor #3. In the first polymerization reactor #1 and the second polymerization reactor #2, propylene monomers undergo polymerization in the presence of catalyst and hydrogen. Before the material from the outlet of the second polymerization reactor #2 undergoes gas-solid separation or gas-liquid-solid separation, it is introduced into the horizontal deep polymerization reactor #3, and a catalyst modifier is added to it to quickly eliminate chain transfer agents in the reactant system, allowing the reactants in the material to continue the deep polymerization reaction, producing ultra-high molecular weight components, and obtaining propylene homopolymer.

[0149] in,

[0150] The feed rate of the active catalyst component in the first polymerization reactor #1 is 0.56 kg / h, the feed rate of the co-catalyst component MAO is 1.2 kg / h, the feed rate of propylene is 46.2 t / h, the feed rate of hydrogen is 0.4 kg / h, and the output of the first polymerization reactor #1 is 41.6 t / h.

[0151] The propylene feed rate of the second polymerization reactor #2 is 23.1 t / h, the hydrogen feed rate is 0.1 kg / h, and the output of the second polymerization reactor #2 is 20.8 t / h.

[0152] The reaction time for both the first polymerization reactor #1 and the second polymerization reactor #2 is 1 hour.

[0153] The feed rate of catalyst modifier to the horizontal deep polymerization reactor #3 is 10 g / h, the material residence time (polymerization reaction time) is 30 min, and the output (load) of the horizontal deep polymerization reactor #3 is controlled at 6.3 t / h. The horizontal deep polymerization reactor #3 has a length-to-diameter ratio of 5.6. It is designed with a gas-solid separation dome and five zones. The first zone has one catalyst modifier injection nozzle for feeding the catalyst modifier. The position of the catalyst modifier injection nozzle is perpendicular to the material level surface and avoids the dome. The horizontal deep polymerization reactor #3 is equipped with... 45 sets of T-shaped The agitator blades are arranged in groups, with two blades in each group arranged at 180°. The phase of each group of agitator blades is staggered by 60° from the phase of the next group of agitator blades along the axis. The blade width is 300mm.

[0154] The polymerization temperature is 60-80℃, the pressure is 2.0-2.3MPa, and the production load of the unit is 68.8t / h.

[0155] The polymer powder obtained from the first polymerization reactor #1 and the polymer powder obtained from the second polymerization reactor #2 both have an MFR of 3.4 g / 10 min, a weight-average molecular weight (MW) of 398576, and a molecular weight distribution width (MWD) of 2.9.

[0156] The polymer powder prepared by the horizontal deep polymerization reactor #3 has an MFR of 2.0 g / 10 min, a weight-average molecular weight of MW = 487546, and a distribution width MWD of 3.8.

[0157] Comparative Example 1

[0158] Taking a large-scale horizontal gas-phase polypropylene unit as an example, a full-process model is performed, using Zn catalyst to produce propylene homopolymer; the reaction unit consists of two reactors connected in series: the first polymerization reactor #1 and the second polymerization reactor #2 are connected in series; wherein,

[0159] The feed rates of the active catalyst component in the first polymerization reactor #1 are 1.27 kg / h, the feed rates of the co-catalyst component AlEt3 are 4.52 kg / h, the feed rates of the external electron donor diisobutyldimethoxysilane (DIBDMS, B-donor) are 0.67 kg / h, the feed rate of propylene is 46.2 t / h, and the feed rate of hydrogen is 0.9 kg / h; the output of the first polymerization reactor #1 is 41.7 t / h.

[0160] The propylene feed rate of the second polymerization reactor #2 is 23.1 t / h, the hydrogen feed rate is 0.45 kg / h, and the output of the second polymerization reactor #2 is 20.8 t / h.

[0161] The polymerization temperature is 60-70℃, the pressure is 2.0-2.3MPa, and the production load of the unit is 62.5t / h;

[0162] The overall molar ratio of the polymerization catalyst was controlled to be Al / Si = 12, and the molar ratio of Al / Mg = 4.

[0163] The reaction time for both the first polymerization reactor #1 and the second polymerization reactor #2 is 1 hour.

[0164] The polymer powder obtained from the first polymerization reactor #1 and the polymer powder obtained from the second polymerization reactor #2 both have an MFR of 3.0 g / 10 min, a weight-average molecular weight (MW) of 352698, and a molecular weight distribution width (MWD) of 4.9.

[0165] Comparative Example 2

[0166] Taking a large-scale horizontal gas-phase polypropylene unit as an example, a full-process model is performed, using Zn catalyst to produce propylene-ethylene random copolymers; the reaction unit consists of two reactors connected in series: the first polymerization reactor #1 and the second polymerization reactor #2 are connected in series, wherein,

[0167] The feed rates of the active catalyst component in the first polymerization reactor #1 are 0.99 kg / h, the feed rates of the co-catalyst component AlEt3 are 8.84 kg / h, the feed rates of the external electron donor diisopropyl dimethoxysilane (DIPDMS, P-donor) are 5.27 kg / h, the feed rates of propylene are 40.2 t / h, the feed rates of ethylene are 1.63 t / h, and the feed rates of hydrogen are 1.0 kg / h; the output of the first polymerization reactor #1 is 37.5 t / h.

[0168] The second polymerization reactor #2 has a propylene feed rate of 16.5 t / h, an ethylene feed rate of 8.43 t / h, a hydrogen feed rate of 1.1 kg / h, and a production capacity of 18.7 t / h.

[0169] The polymerization temperature is 60-70℃, and the pressure is 2.0-2.3MPa; the production load of the unit is 56.2t / h.

[0170] The overall molar ratio of the polymerization catalyst was controlled to Al / Si = 3, and the molar ratio of Al / Mg = 10.

[0171] The reaction time for both the first polymerization reactor #1 and the second polymerization reactor #2 is 1 hour.

[0172] The polymer powder obtained from the first polymerization reactor #1 and the polymer powder obtained from the second polymerization reactor #2 both have an MFR of 1.5 g / 10 min, a weight-average molecular weight Mw of 453176, a molecular weight distribution width MWD of 5.0, and a total ethylene content of 4.3 wt%.

[0173] Comparative Example 3

[0174] Taking a large-scale horizontal gas-phase polypropylene unit as an example, a full-process model is performed, using Zn catalyst to produce propylene-ethylene impact copolymer; the reaction unit consists of two reactors connected in series: the first polymerization reactor #1 and the second polymerization reactor #2 are connected in series, wherein,

[0175] The feed rates of the active catalyst component in the first polymerization reactor #1 are 1.71 kg / h, the feed rates of the co-catalyst component AlEt3 are 6.09 kg / h, the feed rates of the external electron donor diisopropyl dimethoxysilane (DIPDMS, P-donor) are 1.57 kg / h, the feed rate of propylene is 44.7 t / h, and the feed rate of hydrogen is 10.5 kg / h; the output of the first polymerization reactor #1 is 39.8 t / h.

[0176] The second polymerization reactor #2 has a propylene feed rate of 4.4 t / h, an ethylene feed rate of 4.7 t / h, a hydrogen feed rate of 2.7 kg / h, and a production capacity of 7.8 t / h.

[0177] The polymerization temperature is 60-70℃, the pressure is 2.0-2.3MPa, and the production load of the unit is 47.6t / h;

[0178] The overall molar ratio of the polymerization catalyst was controlled to be Al / Si = 6, and the molar ratio of Al / Mg = 4.

[0179] The reaction time for both the first polymerization reactor #1 and the second polymerization reactor #2 is 1 hour.

[0180] The MFR of the polymer powder obtained from the first polymerization reactor #1 was 37.8 g / 10 min, and the MFR of the polymer powder obtained from the second polymerization reactor #2 was 20.0 g / 10 min; the weight-average molecular weight of the polymer powder obtained from the first polymerization reactor #1 was Mw = 187210, and the weight-average molecular weight of the polymer powder obtained from the second polymerization reactor #2 was Mw = 225918, with a molecular weight distribution width (MWD) of 5.1; the total ethylene content was 9.1 wt%, and the ethylene content of the rubber segment was 56.0 wt%.

[0181] Comparative Example 4

[0182] Taking a large-scale horizontal gas-phase polypropylene unit as an example, a full-process model is performed, using a metallocene catalyst to produce propylene homopolymer; the reaction unit consists of two reactors connected in series: the first polymerization reactor #1 and the second polymerization reactor #2 are connected in series, wherein,

[0183] The feed rate of the active catalyst component in the first polymerization reactor #1 is 0.56 kg / h, the feed rate of the co-catalyst component MAO is 1.2 kg / h, the feed rate of propylene is 46.2 t / h, the feed rate of hydrogen is 0.4 kg / h, and the output of the first polymerization reactor #1 is 41.6 t / h.

[0184] The propylene feed rate of the second polymerization reactor #2 is 23.1 t / h, the hydrogen feed rate is 0.1 kg / h, and the output of the second polymerization reactor #2 is 20.8 t / h.

[0185] The polymerization temperature is 60-80℃, the pressure is 2.0-2.3MPa, and the production load of the unit is 62.4t / h;

[0186] The reaction time for both the first polymerization reactor #1 and the second polymerization reactor #2 is 1 hour.

[0187] The polymer powder obtained from the first polymerization reactor #1 and the polymer powder obtained from the second polymerization reactor #2 both have an MFR of 3.4 g / 10 min, a weight-average molecular weight of MW = 398576, and a molecular weight distribution width MWD = 2.9.

[0188] Table 1. Partial experimental conditions and performance of the products obtained in Examples 1-4 and Comparative Examples 1-3.

[0189]

[0190]

[0191] Table 2 shows some experimental conditions and performance of the products obtained in Example 5 and Comparative Example 4.

[0192]

[0193] Comparative Example 5

[0194] The polymerization process was carried out as in Example 2 to produce a propylene-ethylene random copolymer, except that some parameters of the stirring blade assembly in the horizontal deep polymerization reactor #3 were replaced with 5 sets. Gate type The agitator blades are arranged in groups, with the two blades of each group arranged at 180°. The phase of each group of agitator blades is staggered by 90° from the phase of the next group of agitator blades along the axis. The blade width is 300mm.

[0195] The remaining steps are basically the same as in Example 2. The performance indicators of the final product are shown in Table 3.

[0196] Example 6:

[0197] The polymerization steps were carried out in accordance with Example 2 to produce a propylene-ethylene random copolymer. The difference was that some parameters of the stirring blade group set in the horizontal deep polymerization reactor #3 were replaced as follows: there were 5 sets of T-shaped stirring blade groups, and the two blades of each stirring blade group were arranged at 180°. The phase of each stirring blade group was staggered by 45° from the phase of the next stirring blade group along the axis. The blade width was 600 mm.

[0198] The remaining steps are basically the same as in Example 2. The performance indicators of the final product are shown in Table 3.

[0199] Table 3 shows some of the experimental conditions and properties of the products obtained in Comparative Example 5 and Example 6.

[0200]

[0201]

[0202] This invention, by introducing a deep polymerization reactor at the end of a conventional polymerization reaction and by arranging and designing its agitator, can influence the distribution of catalyst modifiers and materials, thereby improving the uniformity of polypropylene resin product distribution. In other words, by rationally designing the structure of the deep polymerization reactor and the agitator, a more uniformly distributed polypropylene resin product can be obtained, while the catalyst utilization efficiency is improved.

[0203] In Comparative Examples 1-4, the lack of a deep polymerization reactor at the end of the conventional polymerization reaction, and the unreasonable design of the stirring blade assembly of the deep polymerization reactor in Comparative Example 5, all resulted in low production efficiency during the polyolefin preparation process and insufficient utilization of the polymerization catalyst. Furthermore, the resulting polyolefin products exhibited poor particle size distribution uniformity, ultimately negatively impacting the quality of the polypropylene products.

[0204] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the spirit of the invention.

Claims

1. A method for olefin polymerization, characterized in that, Includes the following steps: (1) In a polymerization reactor, in the presence of a polymerization catalyst and hydrogen, olefin monomers undergo coordination polymerization, or olefin monomers undergo coordination polymerization with one or more comonomers. (2) A deep polymerization reactor is connected in series at the end of the polymerization reactor described in step (1). Before the material from the outlet of the polymerization reactor described in step (1) undergoes gas-solid separation or gas-liquid-solid separation, the material after the polymerization reaction in step (1) is introduced into the deep polymerization reactor, and a catalyst modifier is added thereto to quickly eliminate the chain transfer agent in the reactant system, allowing the reactants in the material to continue the deep polymerization reaction, producing ultra-high molecular weight components, and obtaining polyolefins; wherein: The deep polymerization reactor is a horizontal deep polymerization reactor with a length-to-diameter ratio of 2 to 15, preferably 5 to 6. The deep polymerization reactor has a stirring shaft and several stirring blades; two stirring blades are arranged at 180° on the same phase of the stirring shaft, which is called a stirring blade group; the phase of each stirring blade group is staggered by 90°, 60° or 45° from the phase of the next stirring blade group along the stirring shaft; the width of the blades is 50-600mm.

2. The olefin polymerization method according to claim 1, characterized in that, Step (2) The upper part of the deep polymerization reactor is provided with 0-3 gas-solid separation domes, and the deep polymerization reactor is provided with 2-6 zones, and a catalyst modifier injection nozzle is provided in any zone or in each zone for catalyst modifier feeding. The position of the catalyst modifier injection nozzle is perpendicular to the material level in the deep polymerization reactor, and the position of the catalyst modifier injection nozzle avoids the position of the dome.

3. The olefin polymerization method according to claim 1 or 2, characterized in that, The deep polymerization reactor has 5-60 stirring blades arranged along the stirring shaft; The impeller blades are T-shaped.

4. The olefin polymerization method according to any one of claims 1-3, characterized in that, The polymerization process of the coordination polymerization reaction in step (1) is selected from one or more of the following: gas phase polymerization process, slurry polymerization process, and slurry-gas phase combined process; The polymerization reactor for the coordination polymerization reaction in step (1) can be a single polymerization reactor, or multiple polymerization reactors connected in series, or a prepolymerization reactor connected in series with a single polymerization reactor, or a prepolymerization reactor connected in series with multiple polymerization reactors.

5. The olefin polymerization method according to any one of claims 1-4, characterized in that, The polymerization reactor in step (1) is either a first polymerization reactor #1 connected in series with a second polymerization reactor #2, or a prepolymerization reactor connected in series with the first polymerization reactor #1 and the first polymerization reactor #1 connected in series with the second polymerization reactor #2; and, A deep polymerization reactor #3 is connected in series at the end of the second polymerization reactor #2.

6. The olefin polymerization method according to any one of claims 1-5, characterized in that, The olefin monomer is propylene; The comonomer is an α-olefin, preferably selected from one or more of ethylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-nonene, and 1-decene.

7. The olefin polymerization method according to any one of claims 1-6, characterized in that, The material exiting the polymerization reactor in step (1) is still reactive, and includes: polyolefin powder generated in the preceding polymerization reactor, unreacted monomers, hydrogen, polymerization catalyst, inert gas and other small amounts of saturated alkanes.

8. The olefin polymerization method according to any one of claims 1-7, characterized in that, The catalyst modifier is a mixture of organometallic compounds and alkylaluminum compounds; The general formula of the organometallic compound is R(R')-MX(X'), where: R and R' are each independently cyclopentadienyl, indene, or fluorenyl without or with substituents, wherein the substituents are preferably selected from methyl, ethyl, propyl, butyl, or cycloalkyl. M is a transition metal element, preferably selected from Fe, Ti, Cr, and Mn; X and X' are each independently a halogen atom, an alkyl group, or an alkoxy group; Preferably, the organometallic compound is selected from one or more of bis(cyclopentadienyl)titanium chloride, bis(cyclopentadienyl)methoxytitanium chloride, bis(cyclopentadienyl)ethoxytitanium chloride, and bis(cyclopentadienyl)phenoxytitanium chloride; Preferably, the alkylaluminum compound is selected from one or more of trimethylaluminum, triethylaluminum, tributylaluminum, triisobutylaluminum, trihexylaluminum, trioctylaluminum, tridecylaluminum, dimethylaluminum chloride, diethylaluminum chloride, dibutylaluminum chloride, and diisobutylaluminum chloride, and more preferably triethylaluminum; Preferably, the molar ratio of the organometallic compound to the alkylaluminum compound is 1:1 to 1:10, more preferably 1:6 to 1:10; Preferably, the molar ratio of the catalyst modifier to the initial total amount of hydrogen in the system is in the range of 1 / 100 to 1 / 100000.

9. The olefin polymerization method according to any one of claims 1-8, characterized in that, The mechanical properties of the resulting polyolefin resin products are improved by 10% or more; The efficiency of the polymerization catalyst is improved by 1%-30%; The content of ultra-high molecular weight components with a molecular weight ≥ 7 million in the polyolefin is 0.1wt%-30wt%.

10. The polyolefin obtained by the olefin polymerization method according to any one of claims 1-9, characterized in that, The polyolefin contains an ultra-high molecular weight component with a molecular weight ≥ 7 million, and the content of the ultra-high molecular weight component is 0.1wt%-30wt%.

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