Polyolefin production method and device

Abstract

A polyolefin production method and a device, belonging to the field of olefin polymerization. The method comprises using as a polymerization solvent in a first reactor a mother liquor containing a polymer having a low molecular weight; then introducing a slurry product in the first reactor to a second reactor, and a slurry product discharged from the second reactor undergoing steps of washing, filtration, drying, granulation, etc.; and / or, washing the slurry product in the first reactor and then performing filtration, drying, granulation, and other steps on same together with the slurry product discharged from the second reactor, so as to finally obtain a high-performance polyolefin product having an ultra-wide molecular weight distribution. The present invention can achieve improvement both in the processing performance and using performance of polyolefins and has the advantages of simple technological process, high operation flexibility, etc.

Description

Polyolefin production method and device

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of Chinese patent application No. 202311025840.9 filed on August 15, 2023, the contents of which are incorporated herein by reference. Technical Field

[0003] The present invention belongs to the field of olefin polymerization, and in particular relates to a polyolefin production method and device. Background Art

[0004] Polyethylene is a thermoplastic resin that is widely used in agricultural production, petrochemicals, construction, and municipal engineering due to its advantages such as good chemical stability, chemical corrosion resistance, good processing performance, and excellent electrical insulation. The polyethylene production process is divided into slurry process, gas phase process, and solution process. Compared with other production processes, the slurry process was developed earlier and has excellent comprehensive performance. The slurry polyethylene process mainly produces high-density polyethylene grades such as pipes, fibers, hollow and other general grades through two or three kettles in series. With increasingly stringent environmental regulations and more extensive market demand for polyolefin products, competition in the polyolefin industry is becoming increasingly fierce, and the frequency of technological upgrades and product replacements is accelerating. High-performance polyolefin grades have become the research focus of the slurry polyethylene process.

[0005] The rapid development of gas-phase processes and catalysts in recent years has significantly impacted existing slurry processes. Consequently, improving the performance of polyethylene produced by slurry processes and expanding their production range are key areas of focus for industrial plants. In summary, the present invention aims to develop a new slurry polyolefin production process that enables the production of high-performance, high-value-added polyethylene products.

[0006] Summary of the Invention

[0007] The present invention aims to overcome the deficiencies of the prior art and provides a polyolefin production method and device. The polyolefin produced by the production method of the present invention can achieve good tensile strength, modulus and impact resistance.

[0008] To achieve the above object, the present invention provides a method for producing polyolefins, wherein an oligomer and a solvent are prepared into a mother liquid, the weight average molecular weight of the oligomer is 150-10000 g / mol, the molecular weight distribution of the oligomer is 2-50, and the branching degree of the oligomer is 0.01-100C / 10000C;

[0009] (A) introducing the mother liquor into a first reactor, introducing a reaction monomer and a catalyst into the first reactor to cause a polymerization reaction to generate a first slurry containing a first polymer powder, introducing the first slurry in the first reactor into a second reactor, and simultaneously introducing a reaction monomer and a catalyst into the second reactor to cause a polymerization reaction to generate a second slurry A containing a second polymer powder A, introducing the second slurry A in the second reactor into a scrubber, and simultaneously introducing a solvent into the scrubber to dissolve low molecular weight polymers free on the surface of the second polymer powder A and / or low molecular weight polymers suspended in the second slurry A to obtain a third slurry A; introducing the third slurry A in the scrubber into a liquid-solid separator for liquid-solid separation;

[0010] Alternatively, (B) introducing the mother liquor into a first reactor, introducing a reaction monomer and a catalyst into the first reactor to cause a polymerization reaction to generate a first slurry containing a first polymer powder, introducing the first slurry in the first reactor into a scrubber, and simultaneously introducing a solvent into the scrubber to dissolve low molecular weight polymers free on the surface of the first polymer powder and / or low molecular weight polymers suspended in the first slurry to obtain a third slurry B; introducing the third slurry B in the scrubber into a liquid-solid separator; introducing a reaction monomer and a catalyst into a second reactor to cause a polymerization reaction to generate a second slurry B containing a second polymer powder B, introducing the second slurry B in the second reactor into the liquid-solid separator, and the liquid-solid separator mixing the third slurry B and the second slurry B and performing liquid-solid separation on the mixed slurry;

[0011] The liquid separated by the liquid-solid separator in step (A) or (B) is subjected to solvent refining treatment to obtain a solvent and a low molecular weight polymer, and the solid separated by the liquid-solid separator is dried and sent to a granulation system to obtain polyolefin.

[0012] A second aspect of the present invention provides a device for implementing the above-mentioned polyolefin production method, wherein the device comprises:

[0013] A mother liquor preparation tank for preparing mother liquor with oligomer and solvent, wherein the mother liquor preparation tank is provided with an oligomer inlet, a solvent inlet and a mother liquor outlet;

[0014] A first reactor and a second reactor for olefin polymerization, wherein the first reactor is provided with a catalyst inlet, a mother liquor inlet, a reaction monomer inlet, and a slurry outlet, and the second reactor is provided with a catalyst inlet, optionally a slurry inlet, a reaction monomer inlet, and a slurry outlet;

[0015] A washer for washing and dissolving free low molecular weight polymers, wherein the washer is provided with a slurry inlet, a solvent inlet, and a slurry outlet;

[0016] A liquid-solid separator for liquid-solid separation of slurry, the liquid-solid separator being provided with a first slurry inlet, a second slurry inlet, a liquid outlet, and a solid outlet;

[0017] A dryer for drying polymer powder, wherein the dryer is provided with a solid inlet and a solid outlet;

[0018] A granulator for granulating polymer powder, wherein the granulator is provided with a solid feed port and a product outlet;

[0019] Solvent refining systems for solvent refining and separation;

[0020] The mother liquor outlet of the mother liquor preparation tank is connected to the mother liquor inlet of the first reactor;

[0021] The slurry outlet of the first reactor is connected to the slurry inlet of the second reactor and / or to the slurry inlet of the scrubber;

[0022] The slurry outlet of the second reactor is connected to the slurry inlet of the scrubber and / or is connected to the first slurry inlet of the liquid-solid separator;

[0023] The slurry outlet of the scrubber is connected to the second slurry inlet of the liquid-solid separator;

[0024] The liquid outlet of the liquid-solid separator is connected to the solvent refining system, and the solid outlet of the liquid-solid separator is connected to the solid inlet of the dryer;

[0025] The solid outlet of the dryer is connected to the solid feeding port of the granulator;

[0026] The solvent refining system is connected to at least one of the oligomer inlet, the solvent inlet of the scrubber, and the solvent inlet of the mother liquor preparation tank.

[0027] Through the above technical solution, the polyolefin production method and device provided by the present invention have the following beneficial effects:

[0028] The present invention uses a mother liquor containing oligomers as a polymerization solvent in a first reactor, then introduces a first slurry prepared in the first reactor into a second reactor, and performs washing, filtering, drying, granulation and other processes on a second slurry A discharged from the second reactor; and / or washes the first slurry in the first reactor and then mixes it with a second slurry B prepared in the second reactor, and then performs filtering, drying, granulation and other processes to obtain a high-performance polyolefin product with an ultra-wide molecular weight distribution, so that the polyolefin can have a combination of tensile strength, modulus and impact resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] FIG1 is a schematic diagram of a polyolefin production device provided by the present invention.

[0030] FIG2 is a schematic diagram of another polyolefin production device provided by the present invention.

[0031] Among them: 1-mother liquor preparation tank; 2-first reactor; 3-second reactor; 4-washer; 5-liquid-solid separator; 6-dryer; 7-granulator. DETAILED DESCRIPTION

[0032] The endpoints of the ranges and any values ​​disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

[0033] In one aspect, the present invention provides a method for producing polyolefins, wherein an oligomer and a solvent are prepared into a mother liquid, wherein the weight average molecular weight of the oligomer is 150-10000 g / mol, the molecular weight distribution of the oligomer is 2-50, and the branching degree of the oligomer is 0.01-100C / 10000C;

[0034] (A) introducing the mother liquor into a first reactor, introducing a reaction monomer and a catalyst into the first reactor to cause a polymerization reaction to generate a first slurry containing a first polymer powder, introducing the first slurry in the first reactor into a second reactor, and simultaneously introducing a reaction monomer and a catalyst into the second reactor to cause a polymerization reaction to generate a second slurry A containing a second polymer powder A, introducing the second slurry A in the second reactor into a scrubber, and simultaneously introducing a solvent into the scrubber to dissolve low molecular weight polymers free on the surface of the second polymer powder A and / or low molecular weight polymers suspended in the second slurry A to obtain a third slurry A; introducing the third slurry A in the scrubber into a liquid-solid separator for liquid-solid separation;

[0035] Alternatively, (B) introducing the mother liquor into a first reactor, introducing a reaction monomer and a catalyst into the first reactor to cause a polymerization reaction to generate a first slurry containing a first polymer powder, introducing the first slurry in the first reactor into a scrubber, and simultaneously introducing a solvent into the scrubber to dissolve low molecular weight polymers free on the surface of the first polymer powder and / or low molecular weight polymers suspended in the first slurry to obtain a third slurry B; introducing the third slurry B in the scrubber into a liquid-solid separator; introducing a reaction monomer and a catalyst into a second reactor to cause a polymerization reaction to generate a second slurry B containing a second polymer powder B, introducing the second slurry B in the second reactor into the liquid-solid separator, and the liquid-solid separator mixing the third slurry B and the second slurry B and performing liquid-solid separation on the mixed slurry;

[0036] The liquid separated by the liquid-solid separator in step (A) or (B) is subjected to solvent refining treatment to obtain a solvent and a low molecular weight polymer, and the solid separated by the liquid-solid separator is dried and sent to a granulation system to obtain polyolefin.

[0037] In some embodiments of the present invention, the weight average molecular weight of the oligomer is 150-10000 g / mol, and the molecular weight distribution of the oligomer is 2-50.

[0038] According to a preferred embodiment of the present invention, the weight average molecular weight of the oligomer is 200-3000 g / mol, and the molecular weight distribution of the oligomer is 2-20.

[0039] According to a preferred embodiment of the present invention, the weight average molecular weight of the oligomer is 200-3000 g / mol, and the molecular weight distribution of the oligomer is 2-10.

[0040] In some embodiments of the present invention, the branching degree of the oligomer is 0.01-100C / 10000C, preferably 0.03-50C / 10000C, and more preferably 0.5-100C / 10000C.

[0041] According to a preferred embodiment of the present invention, the branching degree of the oligomer is 15-40C / 10000C.

[0042] According to a preferred embodiment of the present invention, the branching degree of the oligomer is 15-18C / 10000C.

[0043] In some embodiments of the present invention, the oligomer is selected from at least one of polyethylene wax, polypropylene wax, polyamide wax, Fischer-Tropsch wax, paraffin wax, oxidized polyethylene wax, and oxidized polypropylene wax.

[0044] According to a preferred embodiment of the present invention, the oligomer is polyethylene wax.

[0045] In the present invention, since oligomers may undergo minor changes in molecular weight, molecular weight distribution, or degree of branching during the polymerization of polyolefins, the low molecular weight polymer in the above-mentioned method of the present invention is a collective term for oligomers that do not undergo these changes during the reaction and oligomers that undergo these changes. The low molecular weight polymer may be different from the oligomer used to prepare the mother liquor. If the liquid separated by the liquid-solid separator in step (A) or (B) of the present invention (obtained by solid-liquid separation) is subjected to solvent refining treatment to obtain a low molecular weight polymer that meets the requirements of the present invention for oligomers (molecular weight, molecular weight distribution, or degree of branching), it can be reused for mother liquor preparation. However, if the low molecular weight polymer obtained by this treatment does not meet the requirements of the present invention for oligomers, it cannot be directly reused.

[0046] In some embodiments of the present invention, the oligomers in the mother liquor are completely dissolved in the solvent.

[0047] In some embodiments of the present invention, the oligomers in the mother liquor are partially dissolved in the solvent.

[0048] In the present invention, the complete dissolution of the oligomer means that the mother liquor formed by the oligomer being completely dissolved in the solvent is a homogeneous liquid; the partial dissolution of the oligomer in the solvent means that the mother liquor formed by the oligomer being incompletely dissolved in the solvent is a liquid-solid two-phase slurry.

[0049] In some embodiments of the present invention, the mass ratio of the oligomer introduced into the first reactor to the first polymer powder is 1:100-1:1, preferably 1:10-1:3.

[0050] In the present invention, when the mass ratio of the oligomer to the first polymer powder in the first reactor satisfies the above range, the mechanical properties of the product can be regulated to obtain products of different grades.

[0051] In some embodiments of the present invention, the reactive monomer is one or more C2-C20 olefins. Preferably, the reactive monomer is selected from at least one of ethylene, 1-hexene and 1-butene.

[0052] In the present invention, there is no particular limitation on the amount of the reaction monomers in the first reactor and the second reactor, and those skilled in the art can adjust the amount of the reaction monomers according to needs.

[0053] In the present invention, the reaction monomers in the first reactor and the second reactor may be the same or different.

[0054] In some embodiments of the present invention, the catalyst comprises a main catalyst and a co-catalyst. The main catalyst is selected from at least one of a Ziegler-Natta catalyst, a metallocene catalyst, a non-metallocene catalyst, a chromium-based catalyst, a late transition metal catalyst, and an early transition metal catalyst; and the co-catalyst is selected from one or more of an aluminum alkyl, an alkylaluminoxane, a modified alkylaluminoxane, and a borane. For example, a modified alkylaluminoxane refers to an alkylaluminoxane in which some methyl groups are replaced with aryloxy groups and / or isobutyl groups.

[0055] In the present invention, there is no particular limitation on the amount of the main catalyst and the co-catalyst in the catalyst. Those skilled in the art can configure the catalyst according to conventional amounts in the art. In the present invention, there is no particular limitation on the amount of the catalyst in the first reactor and the second reactor. Those skilled in the art can select the amount of the catalyst according to preparation requirements.

[0056] In some embodiments of the present invention, the reaction temperature of the first reactor is -30°C to 200°C, and the reaction pressure is 0.1-10 MPa.

[0057] According to a preferred embodiment of the present invention, the reaction temperature of the first reactor is 65-80° C., and the reaction pressure is 0.4-3 MPa.

[0058] In some embodiments of the present invention, the reaction temperature of the second reactor is 40° C. to 150° C., and the reaction pressure is 0.3-6 MPa, preferably 0.3-5 MPa.

[0059] According to a preferred embodiment of the present invention, the reaction temperature of the second reactor is 75-85° C., and the reaction pressure is 0.6-5 MPa.

[0060] In some embodiments of the present invention, the solvent is a C3-C15 saturated hydrocarbon. For example, the solvent can be selected from at least one of propane, butane, pentane, 2-methylbutane, 2,2-dimethylpropane, cyclopentane, cyclohexane, hexane, heptane, octane, nonane, decane, undecane, dodecane, tridecane, tetradecane, and pentadecane.

[0061] According to a preferred embodiment of the present invention, the solvent is heptane and / or hexane.

[0062] In the present invention, there is no particular limitation on the amount of the solution introduced into the scrubber, and those skilled in the art can adjust the amount of the solvent according to the solubility of the low molecular weight polymer.

[0063] In the present invention, the solvent in the mother liquor is of the same type as the solvent introduced into the scrubber.

[0064] According to the present invention, a polyolefin production method comprises the following steps: preparing a mother liquor with an oligomer and a solvent, wherein the oligomer has a weight-average molecular weight of 150-10,000 g / mol, a molecular weight distribution range of 2-50, and a degree of branching of 0.5-100C / 10,000C; introducing the mother liquor into a first reactor, introducing a reaction monomer and a catalyst into the first reactor to undergo a polymerization reaction to generate a first slurry containing a first polymer powder; introducing the first slurry in the first reactor into a second reactor, and simultaneously introducing a reaction monomer and a catalyst into the second reactor to undergo a polymerization reaction to generate a second slurry containing a second polymer powder; introducing the second slurry in the second reactor into a scrubber, and simultaneously introducing a solvent into the scrubber to dissolve low molecular weight polymers free on the surface of the second polymer powder and / or low molecular weight polymers suspended in the second slurry to obtain a third slurry; introducing the third slurry in the scrubber into a liquid-solid separator for liquid-solid separation; subjecting the liquid separated by the liquid-solid separator to solvent refining treatment to obtain a solvent and low molecular weight polymers; and drying the solid separated by the liquid-solid separator and sending it to a granulation system to obtain a high-performance polyolefin product.

[0065] According to another polyolefin production method of the present invention, oligomers and solvents are prepared into a mother liquid, wherein the weight average molecular weight of the oligomers is 150-10000 g / mol, the molecular weight distribution range is 2-50, and the branching degree is 0.5-100C / 10000C; the mother liquid is introduced into a first reactor, and a reaction monomer and a catalyst are introduced into the first reactor to carry out a polymerization reaction to generate a first slurry containing a first polymer powder; the first slurry in the first reactor is introduced into a scrubber, and a solvent is introduced into the scrubber to remove the low molecular weight polymers and / or The low molecular weight polymer suspended in the first slurry is dissolved to obtain a third slurry; the third slurry in the scrubber is introduced into a liquid-solid separator; a reaction monomer and a catalyst are introduced into a second reactor to undergo a polymerization reaction to generate a second slurry containing a second polymer powder; the second slurry in the second reactor is introduced into the liquid-solid separator; the liquid-solid separator mixes the third slurry and the second slurry and performs liquid-solid separation on the mixed slurry; the separated liquid is subjected to solvent refining treatment to obtain a solvent and a low molecular weight polymer; the solid separated by the liquid-solid separator is dried and sent to a granulation system to obtain a high-performance polyolefin product.

[0066] In the present invention, since oligomers may undergo minor changes in molecular weight, molecular weight distribution, or degree of branching during the polymerization of polyolefins, the low molecular weight polymer in the above-mentioned method of the present invention collectively refers to oligomers that do not undergo these changes during the reaction and oligomers that undergo these changes. The low molecular weight polymer may be different from the oligomer used to prepare the mother liquor. If the low molecular weight polymer obtained after solvent refining treatment of the liquid (obtained from solid-liquid separation) in the above-mentioned method meets the requirements for oligomers (molecular weight, molecular weight distribution, or degree of branching) specified in the present invention, it can be reused for mother liquor preparation. However, if the low molecular weight polymer obtained after this treatment does not meet the requirements for oligomers specified in the present invention, it cannot be directly reused.

[0067] A second aspect of the present invention provides a device for implementing the above-mentioned polyolefin production method, wherein the device comprises:

[0068] A mother liquor preparation tank for preparing mother liquor with oligomer and solvent, wherein the mother liquor preparation tank is provided with an oligomer inlet, a solvent inlet and a mother liquor outlet;

[0069] A first reactor and a second reactor for olefin polymerization, wherein the first reactor is provided with a catalyst inlet, a mother liquor inlet, a reaction monomer inlet, and a slurry outlet, and the second reactor is provided with a catalyst inlet, optionally a slurry inlet, a reaction monomer inlet, and a slurry outlet;

[0070] A washer for washing and dissolving free low molecular weight polymers, wherein the washer is provided with a slurry inlet, a solvent inlet, and a slurry outlet;

[0071] A liquid-solid separator for liquid-solid separation of slurry, the liquid-solid separator being provided with a first slurry inlet, a second slurry inlet, a liquid outlet, and a solid outlet;

[0072] A dryer for drying polymer powder, wherein the dryer is provided with a solid inlet and a solid outlet;

[0073] A granulator for granulating polymer powder, wherein the granulator is provided with a solid feed port and a product outlet;

[0074] Solvent refining systems for solvent refining and separation;

[0075] The mother liquor outlet of the mother liquor preparation tank is connected to the mother liquor inlet of the first reactor;

[0076] The slurry outlet of the first reactor is connected to the slurry inlet of the second reactor and / or to the slurry inlet of the scrubber;

[0077] The slurry outlet of the second reactor is connected to the slurry inlet of the scrubber and / or is connected to the first slurry inlet of the liquid-solid separator;

[0078] The slurry outlet of the scrubber is connected to the second slurry inlet of the liquid-solid separator;

[0079] The liquid outlet of the liquid-solid separator is connected to the solvent refining system, and the solid outlet of the liquid-solid separator is connected to the solid inlet of the dryer;

[0080] The solid outlet of the dryer is connected to the solid feeding port of the granulator;

[0081] The solvent refining system is connected to at least one of the oligomer inlet, the solvent inlet of the scrubber, and the solvent inlet of the mother liquor preparation tank.

[0082] In the present invention, the solvent refining system is connected to the oligomer inlet and / or the solvent inlet of the scrubber.

[0083] In some embodiments of the present invention, the device operates continuously through control of valves.

[0084] In some embodiments of the present invention, the device is operated intermittently by control of a valve.

[0085] In the present invention, valves are installed on the material pipelines connecting each reactor, scrubber, liquid-solid separator, dryer, and mother liquor preparation tank. For example, during intermittent operation, the reaction monomers, catalyst, and mother liquor are added to the first reactor at once, and the reaction is carried out after the valves are closed, thus achieving intermittent operation.

[0086] In some embodiments of the present invention, the first reactor is a tank reactor or a loop reactor.

[0087] In some embodiments of the present invention, the second reactor is a tank reactor or a loop reactor.

[0088] In some embodiments of the present invention, the combination of the first reactor and the second reactor is any combination of a tank reactor and a loop reactor.

[0089] According to a preferred embodiment of the present invention, the first reactor and the second reactor are tank reactors.

[0090] According to another preferred embodiment of the present invention, the first reactor is a tank reactor, and the second reactor is a loop reactor.

[0091] In some embodiments of the present invention, the loading factor of the tank reactor is 0.4-1.

[0092] In the present invention, there is no particular limitation on the circulation ratio of the loop reactor, and those skilled in the art can adjust the circulation ratio of the loop reactor according to their needs.

[0093] In some embodiments of the present invention, the liquid-solid separator is selected from a belt filter press, a plate and frame filter press, or a centrifuge.

[0094] According to a preferred embodiment of the present invention, the liquid-solid separator is a centrifuge.

[0095] The present invention uses a mother liquor containing oligomers as a polymerization solvent in a first reactor, then introduces a slurry product from the first reactor into a second reactor, and subjecting the slurry product discharged from the second reactor to processes such as washing, filtering, drying, and granulation, and / or subjecting the slurry product from the first reactor to a washing process and then subjecting it together with the slurry product discharged from the second reactor to processes such as filtering, drying, and granulation, thereby obtaining a high-performance polyolefin product with an ultra-wide molecular weight distribution, thereby achieving simultaneous improvement in the processing performance and use performance of the polyolefin.

[0096] The present invention will be further described below with reference to the embodiments and accompanying drawings, but the protection scope of the present invention is not limited thereto:

[0097] As shown in Figures 1 and 2, the polyolefin production device provided by the present invention includes: a mother liquor preparation tank 1 for preparing a mother liquor with an oligomer and a solvent, the preparation tank being provided with an oligomer inlet, a solvent inlet and a mother liquor outlet; a first reactor 2 and a second reactor 3 for olefin polymerization, the first reactor being provided with a catalyst inlet, a mother liquor inlet, a reaction monomer inlet and a slurry outlet, the second reactor being provided with a catalyst inlet, a slurry inlet, a reaction monomer inlet and a slurry outlet; a washer 4 for washing and dissolving free low molecular weight polymers, the washer being provided with a slurry inlet, a solvent inlet and a slurry outlet; a liquid-solid separator 5 for liquid-solid separation of the slurry, the liquid-solid separator being provided with a There are a first slurry inlet, a second slurry inlet, a liquid outlet, and a solid outlet; a dryer 6 for drying polymer powder, the dryer being provided with a solid inlet and a solid outlet; a granulator 7 for granulating polymer powder, the granulator being provided with a solid feed port and a product outlet; a solvent refining system for solvent refining and separation; the mother liquor outlet of the mother liquor preparation tank being connected to the mother liquor inlet of the first reactor; the slurry outlet of the first reactor being connected to the slurry inlet of the second reactor and / or to the slurry inlet of the scrubber; the slurry outlet of the second reactor being connected to the slurry inlet of the scrubber and / or to the first slurry inlet of the liquid-solid separator; The slurry outlet of the scrubber is connected to the second slurry inlet of the liquid-solid separator; the liquid outlet of the liquid-solid separator is connected to the solvent refining system, and the solid outlet of the liquid-solid separator is connected to the solid inlet of the dryer; the solid outlet of the dryer is connected to the solid feeding port of the granulator; part of the solvent and low molecular weight polymer separated by the solvent refining system (the low molecular weight polymer separated is required to meet the requirements of the oligomer molecular weight, molecular weight distribution or degree of branching of the present invention) are respectively injected into the mother liquor preparation tank through the solvent inlet and the oligomer inlet of the mother liquor preparation tank, and part of the solvent separated by the solvent refining system is injected into the scrubber through the solvent inlet of the scrubber.

[0098] Figures 1 and 2 are schematic flow charts of two polyolefin production methods based on the above-mentioned device, which are formed by opening and closing valves on the pipeline. Both schematic processes can be implemented based on the same set of production equipment mentioned above, and both can produce high-performance polyolefins with ultra-wide molecular weight distribution.

[0099] In the production methods of Figures 1 and 2, the same parts are: the oligomer is added from the oligomer inlet of the mother liquor preparation tank, the solvent is added from the solvent inlet of the mother liquor preparation tank, the mother liquor prepared in the mother liquor preparation tank is introduced into the first reactor, the slurry discharged from the slurry outlet of the scrubber is introduced into the liquid-solid separator through the second slurry inlet of the liquid-solid separator, the liquid discharged from the liquid outlet of the liquid-solid separator is introduced into the solvent refining system, part of the solvent and low molecular weight polymer separated from the solvent refining system (the low molecular weight polymer separated is required to meet the requirements of the oligomer molecular weight, molecular weight distribution or degree of branching of the present invention) are respectively introduced into the mother liquor preparation tank through the oligomer inlet and solvent inlet of the mother liquor preparation tank, part of the solvent separated from the solvent refining system is introduced into the scrubber through the solvent inlet on the scrubber, the polymer discharged from the solid outlet of the liquid-solid separator is introduced into the dryer through the solid inlet of the dryer, the solid discharged from the solid outlet of the dryer enters the granulator through the solid feeding port of the granulator, and the product is obtained at the product outlet of the granulator.

[0100] 1 , the slurry discharged from the slurry outlet of the first reactor is introduced into the second reactor through the slurry inlet of the second reactor by controlling the valve, and the slurry discharged from the slurry outlet of the second reactor is introduced into the scrubber through the slurry inlet of the scrubber.

[0101] In Figure 2, by controlling the valve, the slurry discharged from the slurry outlet of the first reactor is introduced into the scrubber through the slurry inlet of the scrubber, and the slurry discharged from the slurry outlet of the second reactor is introduced into the liquid-solid separator through the first slurry inlet of the liquid-solid separator.

[0102] The oligomer has a weight average molecular weight of 150-10000 g / mol, a molecular weight distribution range of 2-50, and a branching degree of 0.01-100C / 10000C.

[0103] As shown in FIG1 , the polyolefin production device provided by the present invention comprises: a mother liquor preparation tank 1 for preparing a mother liquor with an oligomer and a solvent, the mother liquor preparation tank being provided with an oligomer inlet, a solvent inlet, and a mother liquor outlet; a first reactor 2 and a second reactor 3 for olefin polymerization, the first reactor being provided with a catalyst inlet, a mother liquor inlet, a reaction monomer inlet, and a slurry outlet, and the second reactor being provided with a catalyst inlet, a slurry inlet, a reaction monomer inlet, and a slurry outlet;

[0104] a washer 4 for washing and dissolving free low-molecular-weight polymers, the washer being provided with a slurry inlet, a solvent inlet, and a slurry outlet; a liquid-solid separator 5 for liquid-solid separation of the slurry, the liquid-solid separator being provided with a second slurry inlet, a liquid outlet, and a solid outlet; a dryer 6 for drying the polymer powder, the dryer being provided with a solid inlet and a solid outlet; a granulator 7 for granulating the polymer powder, the granulator being provided with a solid feed port and a product outlet; and a solvent refining system for solvent refining and separation, the solvent refining system being provided with a solvent outlet and an oligomer outlet;

[0105] The mother liquor outlet of the mother liquor preparation tank is connected to the mother liquor inlet of the first reactor;

[0106] The slurry outlet of the first reactor is connected to the slurry inlet of the second reactor;

[0107] The slurry outlet of the second reactor is connected to the slurry inlet of the scrubber;

[0108] The slurry outlet of the scrubber is connected to the second slurry inlet of the liquid-solid separator;

[0109] The liquid outlet of the liquid-solid separator is connected to the solvent refining system, and the solid outlet of the liquid-solid separator is connected to the solid inlet of the dryer;

[0110] The solid outlet of the dryer is connected to the solid feeding port of the granulator;

[0111] Part of the solvent and low molecular weight polymer separated by the solvent refining system (the low molecular weight polymer separated is required to meet the molecular weight, molecular weight distribution or branching degree requirements of the oligomer of the present invention) are respectively injected into the mother liquor preparation tank through the solvent inlet and the oligomer inlet of the mother liquor preparation tank, and part of the solvent separated by the solvent refining system is injected into the scrubber through the solvent inlet of the scrubber.

[0112] According to the schematic diagram of the polyolefin production device in FIG1 , the polyolefin production method includes:

[0113] The oligomer is added from the oligomer inlet of the mother liquid preparation tank, the solvent is added from the solvent inlet of the mother liquid preparation tank, the mother liquid prepared in the mother liquid preparation tank is introduced into the first reactor, the reaction monomer and the catalyst are introduced into the first reactor through the reaction monomer inlet and the catalyst inlet respectively, the slurry discharged from the slurry outlet of the first reactor is introduced into the second reactor through the slurry inlet of the second reactor by control of the valve, the reaction monomer and the catalyst are introduced into the second reactor through the reaction monomer inlet and the catalyst inlet respectively, the slurry discharged from the slurry outlet of the second reactor is introduced into the scrubber through the slurry inlet; the slurry discharged from the slurry outlet of the scrubber is introduced into the liquid-solid separator through the second slurry inlet The separator is provided. The liquid discharged from the liquid outlet of the liquid-solid separator is introduced into a solvent refining system. Part of the solvent and low molecular weight polymer separated from the solvent refining system (the low molecular weight polymer separated is required to meet the requirements of the oligomer molecular weight, molecular weight distribution or degree of branching of the present invention) are respectively introduced into the mother liquid preparation tank through the oligomer inlet and solvent inlet of the mother liquid preparation tank. Part of the solvent separated from the solvent refining system is introduced into the scrubber through the solvent inlet on the scrubber. The polymer discharged from the solid outlet of the liquid-solid separator is introduced into the dryer through the solid inlet of the dryer. The solid discharged from the solid outlet of the dryer enters the granulator through the solid feed port of the granulator, and the product is obtained at the product outlet of the granulator. The weight average molecular weight of the oligomer is 150-10000 g / mol, the molecular weight distribution is 2-50, and the degree of branching is 0.01-100C / 10000C.

[0114] As shown in FIG2 , the polyolefin production device provided by the present invention comprises: a mother liquor preparation tank 1 for preparing a mother liquor with an oligomer and a solvent, the mother liquor preparation tank being provided with an oligomer inlet, a solvent inlet, and a mother liquor outlet; a first reactor 2 and a second reactor 3 for olefin polymerization, the first reactor being provided with a catalyst inlet, a mother liquor inlet, a reaction monomer inlet, and a slurry outlet, and the second reactor being provided with a catalyst inlet, a reaction monomer inlet, and a slurry outlet;

[0115] a washer 4 for washing and dissolving free low-molecular-weight polymers, the washer being provided with a slurry inlet, a solvent inlet, and a slurry outlet; a liquid-solid separator 5 for liquid-solid separation of the slurry, the liquid-solid separator being provided with a first slurry inlet, a second slurry inlet, a liquid outlet, and a solid outlet; a dryer 6 for drying polymer powder, the dryer being provided with a solid inlet and a solid outlet; a granulator 7 for granulating the polymer powder, the granulator being provided with a solid feed port and a product outlet; and a solvent refining system for solvent refining and separation, the solvent refining system being provided with a solvent outlet and an oligomer outlet;

[0116] The mother liquor outlet of the mother liquor preparation tank is connected to the mother liquor inlet of the first reactor;

[0117] The slurry outlet of the first reactor is connected to the slurry inlet of the scrubber;

[0118] The slurry outlet of the second reactor is connected to the first slurry inlet of the liquid-solid separator;

[0119] The slurry outlet of the scrubber is connected to the second slurry inlet of the liquid-solid separator;

[0120] The liquid outlet of the liquid-solid separator is connected to the solvent refining system, and the solid outlet of the liquid-solid separator is connected to the solid inlet of the dryer;

[0121] The solid outlet of the dryer is connected to the solid feeding port of the granulator;

[0122] Part of the solvent and low molecular weight polymer separated by the solvent refining system (the low molecular weight polymer separated is required to meet the requirements of the oligomer molecular weight, molecular weight distribution or branching degree of the present invention) are injected into the mother liquor preparation tank through the solvent inlet and oligomer inlet of the mother liquor preparation tank respectively, and part of the solvent separated by the solvent refining system is injected into the scrubber through the solvent inlet of the scrubber.

[0123] According to the schematic diagram of the polyolefin production device in FIG2 , the polyolefin production method includes:

[0124] The oligomer is added from the oligomer inlet of the mother liquor preparation tank, the solvent is added from the solvent inlet of the mother liquor preparation tank, the mother liquor prepared in the mother liquor preparation tank is introduced into the first reactor, the reaction monomer and the catalyst are introduced into the first reactor through the reaction monomer inlet and the catalyst inlet respectively. The slurry discharged from the slurry outlet of the first reactor is introduced into the scrubber through the slurry inlet of the scrubber through the control of the valve; the slurry discharged from the slurry outlet of the scrubber is introduced into the liquid-solid separator through the second slurry inlet of the liquid-solid separator, the reaction monomer and the catalyst are introduced into the second reactor through the reaction monomer inlet and the catalyst inlet respectively, the slurry discharged from the slurry outlet of the second reactor is introduced into the liquid-solid separator through the first slurry inlet of the liquid-solid separator Separator; liquid discharged from the liquid outlet of the liquid-solid separator is introduced into a solvent refining system; part of the solvent and low molecular weight polymer separated from the solvent refining system (the low molecular weight polymer separated is required to meet the requirements of the oligomer molecular weight, molecular weight distribution or degree of branching of the present invention) are respectively introduced into the mother liquid preparation tank through the oligomer inlet and solvent inlet of the mother liquid preparation tank; part of the solvent separated from the solvent refining system is introduced into the scrubber through the solvent inlet on the scrubber; the polymer discharged from the solid outlet of the liquid-solid separator is introduced into the dryer through the solid inlet of the dryer; the solid discharged from the solid outlet of the dryer enters the granulator through the solid feed port of the granulator, and the product is obtained at the product outlet of the granulator. The molecular weight of the oligomer is 150-10000 g / mol, the molecular weight distribution is 2-50, and the degree of branching is 0.01-100C / 10000C.

[0125] The present invention will be described in detail below through examples.

[0126] Melt index of polyolefin: Melt index meter is used to test the melt index of polyolefin materials.

[0127] A universal testing machine was used to measure the tensile strength, elongation at break, and Young's modulus of the samples. Tensile specimens were prepared using a hot press according to GB / T 1040.2-2008 and allowed to rest for 24-48 hours before testing. The impact strength of the samples was measured using a plastic pendulum impact tester. Simply supported beam impact specimens were prepared using a hot press according to GB / T 1043.2-2018 and allowed to rest for 24-48 hours before testing.

[0128] Molecular weight distribution of polyolefins: High-temperature gel permeation chromatography is used to determine the molecular weight and distribution of polymers. A solution with a mass concentration of 2-5% polyol is prepared using 1,2,4-trichlorobenzene as the solvent. Oscillate at 160°C until the polyethylene is completely dissolved. Filter, sample, and test.

[0129] Example 1

[0130] Olefin polymerization was performed using the apparatus shown in Figure 1. Heptane was used as the solvent. A polyethylene wax with a weight-average molecular weight of 1200 g / mol, a molecular weight distribution of 10, and a degree of branching of 15C / 10,000C was added to a mother liquor preparation tank. The polymer was completely dissolved in the solvent. The prepared mother liquor was introduced into a first reactor. Zigler-Natta catalyst and triisobutylaluminum were simultaneously added to both the first and second reactors. Ethylene was introduced from the bottom of the first reactor, while ethylene and 1-hexene were introduced from the bottom of the second reactor. The slurry discharged from the bottom of the first reactor was introduced into a second reactor. The slurry discharged from the second reactor was subjected to washing, drying, and granulation to obtain a polymer product. Its properties are shown in Table 1. Among them, the mass ratio of the oligomer introduced into the first reactor to the mass ratio of the polymer powder generated in the first reactor is 1:10, the reaction temperature in the first reactor is 80°C and the pressure is 0.4 MPa, and the reaction temperature in the second reactor is 85°C and the pressure is 0.6 MPa. The first reactor and the second reactor are both kettle reactors with charging factors of 0.5 and 0.75 respectively, and the liquid-solid separator is a centrifuge.

[0131] Example 2

[0132] Olefin polymerization was carried out using the apparatus shown in FIG1 , under the same temperature, pressure, catalyst system, and polymerization reactor type as in Example 1. The only difference from Example 1 was that hexane was used as the solvent. In this case, some undissolved oligomers (accounting for 20% by mass of the total oligomers) were suspended in the mother liquor. The properties of the produced polymer are shown in Table 1.

[0133] Example 3

[0134] Olefin polymerization was carried out using the apparatus shown in Figure 1 under the same temperature, pressure, catalyst system and polymerization reactor type as in Example 1, except that a polyethylene wax having a weight-average molecular weight of 2000 g / mol, a molecular weight distribution of 20, and a degree of branching of 18C / 10000C was used. The properties of the polymer produced are shown in Table 1.

[0135] Example 4

[0136] Olefin polymerization was carried out using the apparatus shown in Figure 1 under the same temperature, pressure, catalyst system and polymerization reactor type as in Example 1, except that a polyethylene wax having a weight-average molecular weight of 5000 g / mol, a molecular weight distribution of 30, and a degree of branching of 40C / 10000C was used. The properties of the polymer produced are shown in Table 1.

[0137] Example 5

[0138] Olefin polymerization was carried out using the apparatus shown in FIG1 , under the same temperature, pressure, catalyst system, and polymerization reactor type as in Example 1. The only difference from Example 1 was that the mass ratio of the oligomer introduced into the first reactor to the mass ratio of the first polymer powder was 1:2. The properties of the produced polymer are shown in Table 1.

[0139] Example 6

[0140] Olefin polymerization was carried out using the apparatus shown in FIG1 , under the same temperature, pressure, catalyst system, and polymerization reactor type as in Example 1. The only difference from Example 1 was that the mass ratio of the oligomer introduced into the first reactor to the mass ratio of the first polymer powder was 1:110. The properties of the produced polymer are shown in Table 1.

[0141] Comparative Example 1

[0142] Under the same temperature, pressure, catalyst system and polymerization reactor type as Example 1, the only difference from Example 1 is that no oligomer is added to the mother liquor preparation tank, that is, the mother liquor is pure solvent. The properties of the obtained polymer are shown in Table 1.

[0143] Comparative Example 2

[0144] Olefin polymerization was carried out using the apparatus shown in Figure 1 under the same temperature, pressure, catalyst system and polymerization reactor type as in Example 1, except that a polyethylene wax having a weight-average molecular weight of 20,000 g / mol, a molecular weight distribution of 1.5, and a degree of branching of 200C / 10,000C was used. The properties of the polymer produced are shown in Table 1.

[0145] Example 7

[0146] Olefin polymerization was carried out using the apparatus shown in Figure 2. Heptane was used as the solvent. A polyethylene wax with a weight-average molecular weight of 5000 g / mol, a molecular weight distribution of 30, and a degree of branching of 40C / 10000C was added to a mother liquor preparation tank. Undissolved oligomers (accounting for 40% of the total oligomer mass fraction) were suspended in the mother liquor. The prepared mother liquor was introduced into a first reactor. Zigler-Natta catalyst and methylaluminoxane were simultaneously added to the first and second reactors. Ethylene was introduced from the bottom of the first reactor, while ethylene and 1-butene were introduced from the bottom of the second reactor. The slurry discharged from the bottom of the first reactor was treated in a scrubber and then introduced into a liquid-solid separator. The slurry discharged from the second reactor was then introduced into a liquid-solid separator. The solid separated by the liquid-solid separator was dried, granulated, and other processes to obtain a polymer product. The properties of the polymer are shown in Table 1. Among them, the mass ratio of the oligomer introduced into the first reactor to the polymer powder generated in the first reactor is 1:3, the reaction temperature in the first reactor is 65°C and the pressure is 3 MPa, the reaction temperature in the second reactor is 75°C and the pressure is 6 MPa, the first reactor is a kettle reactor with a charging factor of 0.6, the second reactor is a tubular reaction, and the liquid-solid separator is a centrifuge.

[0147] Example 8

[0148] Under the same temperature, pressure, catalyst system and polymerization reactor type as Example 7, the only difference from Example 3 is that polyethylene wax with a weight-average molecular weight of 2000 g / mol, a molecular weight distribution of 20, and a branching degree of 18C / 10000C is added to the mother liquor. The properties of the obtained polymer are shown in Table 1.

[0149] Table 1

[0150] Table 1

[0151] * Melt index test temperature is 190℃ and load is 10kg.

[0152] From the polymer performance test results in Table 1, it can be seen that the olefin polymer prepared by the device and method provided by the present invention has both good fluidity and excellent mechanical properties.

[0153] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention. The technical content for which protection is sought in the present invention has been fully recorded in the claims.

Claims

1. A method for producing polyolefins, characterized in that: The oligomer and the solvent are mixed into a mother solution, wherein the weight average molecular weight of the oligomer is 150-10000 g / mol, the molecular weight distribution of the oligomer is 2-50, and the branching degree of the oligomer is 0.01-100C / 10000C; (A) introducing the mother liquor into a first reactor, introducing a reaction monomer and a catalyst into the first reactor to undergo a polymerization reaction to generate a first slurry containing a first polymer powder, introducing the first slurry in the first reactor into a second reactor, and simultaneously introducing a reaction monomer and a catalyst into the second reactor to undergo a polymerization reaction to generate a second slurry A containing a second polymer powder A, introducing the second slurry A in the second reactor into a scrubber, and simultaneously introducing a solvent into the scrubber to dissolve low molecular weight polymers free on the surface of the second polymer powder A and / or low molecular weight polymers suspended in the second slurry A to obtain a third slurry A; introducing the third slurry A in the scrubber into a liquid-solid separator for liquid-solid separation; Alternatively, (B) introducing the mother liquor into a first reactor, introducing a reaction monomer and a catalyst into the first reactor to undergo a polymerization reaction to generate a first slurry containing a first polymer powder, introducing the first slurry in the first reactor into a scrubber, and simultaneously introducing a solvent into the scrubber to dissolve low molecular weight polymers free on the surface of the first polymer powder and / or low molecular weight polymers suspended in the first slurry to obtain a third slurry B; introducing the third slurry B in the scrubber into a liquid-solid separator; introducing a reaction monomer and a catalyst into a second reactor to undergo a polymerization reaction to generate a second slurry B containing a second polymer powder B, introducing the second slurry B in the second reactor into the liquid-solid separator, and the liquid-solid separator mixing the third slurry B and the second slurry B and performing liquid-solid separation on the mixed slurry; The liquid separated by the liquid-solid separator in step (A) or (B) is subjected to solvent refining treatment to obtain a solvent and a low molecular weight polymer, and the solid separated by the liquid-solid separator is dried and sent to a granulation system to obtain polyolefin.

2. The method according to claim 1, characterized in that The oligomer is selected from at least one of polyethylene wax, polypropylene wax, polyamide wax, Fischer-Tropsch wax, paraffin wax, oxidized polyethylene wax and oxidized polypropylene wax.

3. The method according to claim 1 or 2, characterized in that: The oligomers in the mother solution are completely dissolved in the solvent, and / or partially dissolved in the solvent.

4. The method according to any one of claims 1 to 3, characterized in that: The mass ratio of the oligomer introduced into the first reactor to the mass ratio of the first polymer powder is 1:100-1:

1.

5. The method according to any one of claims 1 to 4, characterized in that: The reaction temperature of the first reactor is -30°C to 200°C, and the reaction pressure is 0.1-10MPa; The reaction temperature of the second reactor is 40° C. to 150° C., and the reaction pressure is 0.3-6 MPa.

6. A device for implementing the polyolefin production method according to any one of claims 1 to 5, characterized in that: The device comprises: A mother liquid preparation tank (1) for preparing a mother liquid with an oligomer and a solvent, wherein the mother liquid preparation tank is provided with an oligomer inlet, a solvent inlet and a mother liquid outlet; A first reactor (2) and a second reactor (3) for olefin polymerization, wherein the first reactor is provided with a catalyst inlet, a mother liquor inlet, a reaction monomer inlet, and a slurry outlet, and the second reactor is provided with a catalyst inlet, optionally a slurry inlet, a reaction monomer inlet, and a slurry outlet; A washer (4) for washing and dissolving free low molecular weight polymers, wherein the washer is provided with a slurry inlet, a solvent inlet, and a slurry outlet; A liquid-solid separator (5) for liquid-solid separation of slurry, the liquid-solid separator being provided with a first slurry inlet, a second slurry inlet, a liquid outlet, and a solid outlet; A dryer (6) for drying polymer powder, wherein the dryer is provided with a solid inlet and a solid outlet; A granulator (7) for granulating polymer powder, wherein the granulator is provided with a solid feed port and a product outlet; Solvent refining systems for solvent refining and separation; The mother liquid outlet of the mother liquid preparation tank is connected to the mother liquid inlet of the first reactor; The slurry outlet of the first reactor is connected to the slurry inlet of the second reactor and / or to the slurry inlet of the scrubber; The slurry outlet of the second reactor is connected to the slurry inlet of the scrubber and / or is connected to the first slurry inlet of the liquid-solid separator; The slurry outlet of the scrubber is connected to the second slurry inlet of the liquid-solid separator; The liquid outlet of the liquid-solid separator is connected to the solvent refining system, and the solid The outlet is connected to the solid inlet of the dryer; The solid outlet of the dryer is connected to the solid feeding port of the granulator; The solvent refining system is connected to at least one of the oligomer inlet, the solvent inlet of the scrubber and the solvent inlet of the mother liquor preparation tank.

7. The device according to claim 6, characterized in that Continuous operation and / or intermittent operation can be achieved through valve control.

8. The device according to claim 6 or 7, characterized in that The first reactor is a tank reactor or a loop reactor.

9. The device according to any one of claims 6 to 8, characterized in that The second reactor is a tank reactor or a loop reactor.

10. The device according to any one of claims 6 to 9, characterized in that: The liquid-solid separator is selected from a belt filter press, a plate and frame filter press or a centrifuge.

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