Process for promoting phase separation of a polymer solution, process for phase separation of a polymer solution and process for the production of an olefin polymer

Abstract

The present application relates to the field of polymer preparation, and discloses a method for promoting phase separation of a polymer solution. The method for promoting phase separation of the polymer solution comprises: subjecting at least part of the polymer solution to heat treatment under flow so that the polymer solution is separated into a supernatant phase and a concentrated phase, wherein the Reynolds number of the flow of the polymer solution is between 0.02 and 30. The present application reduces the solution phase separation temperature, reduces the solution phase separation time, and significantly reduces the material consumption and energy consumption of the whole process by subjecting to heat treatment under specific Reynolds number conditions, compared with the prior art which only uses heat treatment to separate phases.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of polymer preparation, and relates to a method for promoting phase separation of a polymer solution, a method for phase separation of a polymer solution and a method for preparing an olefin polymer. BACKGROUND

[0002] Solution polymerization process plays an important role in the industry of high molecular materials. Various products such as fibers, rubbers, plastics, elastomers, coatings and adhesives can be produced by using the process. However, the separation of polymers in the polymer solution produced by solution polymerization is more complex than other processes. At present, the catalyst residue is first decomposed and removed by introducing steam into the polymer solution for condensation stripping operation, and then the polymer is separated, and finally the solvent, unreacted monomer, and a small amount of residual water and other volatile components are removed, and the polymer is made into porous small particle products for subsequent drying treatment, and the solvent is collected by a recovery device for recycling.

[0003] In the prior art, there is also a process that uses a liquid-liquid separation method to separate the polymer solution. The polymer solution can exhibit a lower critical solution temperature (LCST) phenomenon, also known as the minimum consolute temperature. As the temperature of the homogeneous polymer solution increases, the polymer solution will form two liquid phases, namely the clear liquid phase and the concentrated liquid phase, at a certain temperature point. The concentrated liquid phase contains most of the polymer, and the clear liquid phase contains a small amount of polymer.

[0004] CN107614541A discloses a method for continuous solution polymerization, which can heat or cool the polymer solution to a temperature within 50℃ of the critical temperature of the solvent; then make the polymer solution pass through a pressure relief valve into a liquid-liquid separator, and reduce or increase the pressure of the polymer solution to a pressure within 50psig of the critical pressure to induce the polymer solution to separate into two liquid phases, the upper phase containing only a small amount of polymer, and the lower phase containing enriched polymer, thereby reducing the required energy for subsequent solvent separation. SUMMARY

[0005] The purpose of the present application is to overcome the limitations of the prior art in liquid-liquid phase separation of polymers from polymer solutions, as well as the defects of high energy consumption and high cost, and to provide a new method for promoting phase separation of polymer solutions, a method for phase separation of polymer solutions and a method for preparing olefin polymers.

[0006] To achieve the above object, the present application provides a method for promoting phase separation of a polymer solution, wherein the method comprises: subjecting at least part of the polymer solution to heat treatment under flow so that the polymer solution separates into a dilute phase and a concentrated phase, wherein the Reynolds number of the flow of the polymer solution is between 0.02 and 30.

[0007] Preferably, at least part of the polymer solution is subjected to heat treatment under shear stress so that the polymer solution separates into a dilute phase and a concentrated phase, wherein the shear stress satisfies the following formula,

[0008] 0.3*μ 2 / (D 2 *ρ)<τ<1000*μ 2 / (D 2 *ρ)

[0009] wherein μ is the viscosity of the polymer solution before phase separation, in units of Pa*s,

[0010] D is the diameter of the phase separation vessel, in units of m,

[0011] ρ is the density of the polymer solution before phase separation, in units of kg / m 3 .

[0012] Preferably, τ satisfies the following formula: 20*μ 2 / (D 2 *ρ)<τ<120*μ 2 / (D 2 *ρ).

[0013] Preferably, the entire polymer solution is subjected to heat treatment under shear stress.

[0014] Preferably, the heat treatment of the polymer solution is carried out under stirring.

[0015] Preferably, the polymer solution is a polymer solution obtained by solution polymerization.

[0016] Preferably, the concentration of the polymer in the polymer solution is between 5 and 20 wt%, preferably between 6 and 15 wt%;

[0017] Preferably, the polymer in the polymer solution is selected from one or more of plastic, rubber and thermoplastic elastomer.

[0018] Preferably, the plastic is selected from one or more of polyethylene, polypropylene, polybutylene, a copolymer of ethylene and one or more α-olefins, and a copolymer of propylene and one or more α-olefins.

[0019] Preferably, the rubber is selected from one or more of butadiene-styrene rubber, butadiene rubber, isoprene rubber and styrene-isoprene rubber.

[0020] Preferably, the thermoplastic elastomer is selected from one or more of copolymers of ethylene with one or more a-olefins, copolymers of propylene with one or more a-olefins, copolymers of ethylene with one or more cyclic olefins, copolymers of ethylene and a-olefins with one or more cyclic olefins, copolymers of ethylene and a-olefins with optional non-conjugated dienes, butene-ethylene copolymers, styrene-butadiene-styrene block copolymers and hydrogenated styrene-butadiene-styrene block copolymers.

[0021] Preferably, the solvent in the polymer solution is selected from one or more of C5-C10 linear or branched alkyl, C5-C10 cycloalkane and C6-C20 aromatic hydrocarbon.

[0022] Preferably, the solvent in the polymer solution is selected from one or more of n-pentane, i-pentane, cyclopentane, n-hexane, i-hexane, cyclohexane, methylcyclohexane, n-heptane, 2-methylheptane, n-octane, i-octane, mixed octane, benzene, toluene, o-xylene, m-xylene and p-xylene.

[0023] Preferably, the temperature of the heat treatment is in the range of the lower critical solution temperature of the polymer solution ± 50°C; more preferably, the temperature of the heat treatment is in the range of the lower critical solution temperature of the polymer solution - 50°C.

[0024] Preferably, the heat treatment is carried out in a phase separation tank; more preferably, the polymer solution is subjected to the heat treatment under stirring in a phase separation tank.

[0025] Preferably, the temperature of the heat treatment is in the range of 100-300°C and the pressure of the heat treatment is in the range of 10-50 bar.

[0026] Preferably, the polymer concentration in the clear liquid phase is less than 1 wt% and the polymer concentration in the concentrated liquid phase is in the range of 8-50 wt%;

[0027] Preferably, the polymer concentration in the concentrated liquid phase is more than 1.35 times, more preferably more than 1.8 times, and even more preferably more than 2.0 times the polymer concentration in the polymer solution.

[0028] According to a second aspect of the present application, there is provided a method for phase separation of a polymer solution, wherein the method comprises the steps of,

[0029] 1) a step of facilitating phase separation of a polymer solution by using the method for facilitating phase separation of a polymer solution according to the present application;

[0030] 2) separating the supernatant phase from the concentrated phase.

[0031] According to a third aspect of the present application, there is provided a process for preparing an olefin polymer, wherein the process comprises the steps of,

[0032] (A) feeding the catalyst system into a polymerization reactor and contacting with one or more olefin monomers, optionally hydrogen, to carry out an olefin polymerization to obtain a polymerization reaction mixture;

[0033] (B) subjecting the polymerization reaction mixture of step A to phase separation using the process for phase separation of a polymer solution according to the present application.

[0034] Compared with the prior art, the present application has the following features:

[0035] Compared with the prior art of phase separation by heat treatment only, the present application has the advantages of lower solution phase separation temperature, shorter solution phase separation time, and 20-40% reduction in material consumption and energy consumption. DETAILED DESCRIPTION

[0036] The endpoints of the ranges and any values disclosed herein are not to be construed as limiting. It is specifically intended that the description in the specification include all such closely related values. For numerical ranges expressed in the format "from X to Y," where X and Y are numbers, it is specifically intended that the range "from X to Y" include X and Y. For numerical ranges expressed in the format "X to Y," where X and Y are numbers, it is specifically intended that the range "X to Y" include X and Y. For numerical ranges expressed in the format "X or below," where X is a number, it is specifically intended that the range "X or below" includes X. For numerical ranges expressed in the format "Y or above," where Y is a number, it is specifically intended that the range "Y or above" includes Y. For numerical ranges expressed in the format "from X to Y or below," where X is less than Y, it is specifically intended that the range "from X to Y or below" includes X, Y, and any amount therebetween. For numerical ranges expressed in the format "from X to Y or above," where X is less than Y, it is specifically intended that the range "from X to Y or above" includes X, Y, and any amount therebetween. For numerical ranges expressed in the format "X or below and Y or above," where X is less than Y, it is specifically intended that the range "X or below and Y or above" includes X, Y, and any amount therebetween.

[0037] The present application provides a method for facilitating phase separation of a polymer solution, wherein the method comprises subjecting at least part of the polymer solution to heat treatment under flow such that the polymer solution flows at a Reynolds number between 0.02 and 30 to separate the polymer solution into a supernatant phase and a concentrated phase.

[0038] In the present application, the method of subjecting part of the polymer solution may, for example, apply a shear force to the polymer solution such that the polymer solution flows at a Reynolds number between 0.02 and 30.

[0039] Preferably, the Reynolds number of the polymer solution flow is between 0.1 and 30. As specific examples of the Reynolds number of the polymer solution flow, the following can be given: 0.05, 0.07, 0.08, 0.09, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4.0, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, 5.0, 5.1, 5.2, 5.3, 5.4, 5.5, 5.6, 5.7, 5.8, 5.9, 6.0, 6.1, 6.2, 6.3, 6.4, 6.5, 6.6, 6.7, 6.8, 6.9, 7.0, 7.1, 7.2, 7.3, 7.4, 7.5, 7.6, 7.7, 7.8, 7.9, 8.0, 8.5, 9.0, 9.5, 10.0, 10.5, 11.0, 11.5, 12.0, 12.5, 13.0, 13.5, 14.0, 14.5, 15.0, 15.5, 16.0, 16.5, 17.0, 17.5, 18.0, 18.5, 19.0, 19.5, 20.0, 20.5, 21.0, 21.5, 22.0, 22.5, 23.0, 23.5, 24.0, 24.5, 25.0, 25.5, 26.0, 26.5, 27.0, 27.5, 28.0, 28.5, 29.0, 29.5, 20.0, etc.

[0040] Preferably, at least part of the polymer solution is subjected to heat treatment under the specific shear force of the present application such that the polymer solution is separated into a supernatant phase and a concentrated phase, wherein the shear force satisfies the following formula,

[0041] 0.3*μ 2 / (D 2 *ρ)<τ<1000*μ 2 / (D 2 *ρ)

[0042] wherein μ is the viscosity of the polymer solution before phase separation, in Pa*s,

[0043] D is the diameter of the phase separation vessel, in m,

[0044] ρ is the density of the polymer solution before phase separation, in kg / m 3 .

[0045] According to the present application, by means of heat treatment under shearing force, the solution phase separation temperature is lowered, the solution phase separation time is reduced, and the material consumption and energy consumption can be significantly reduced, compared with the prior art which only uses heat treatment to separate phases.

[0046] From the aspects of further reducing the phase separation time and lowering the material consumption and energy consumption, preferably, τ satisfies the following formula: 1*μ 2 / (D 2 *ρ)<τ<800*μ 2 / (D 2 *ρ); more preferably, τ satisfies the following formula: 5*μ 2 / (D 2 *ρ)<τ<600*μ 2 / (D 2 *ρ); more preferably, τ satisfies the following formula: 10*μ 2 / (D 2 *ρ)<τ<400*μ 2 / (D 2 *ρ); more preferably, τ satisfies the following formula: 15*μ 2 / (D 2 *ρ)<τ<200*μ 2 / (D 2 *ρ); more preferably, τ satisfies the following formula: 20*μ 2 / (D 2 *ρ)<τ<120*μ 2 / (D 2 *ρ).

[0047] According to the present application, at least part of the polymer solution is subjected to heat treatment under the specific shearing force of the present application, preferably, the whole polymer solution is subjected to heat treatment under the specific shearing force of the present application, that is, part of the polymer solution can be subjected to heat treatment under the specific shearing force of the present application, or the whole polymer solution can be subjected to heat treatment under the specific shearing force of the present application. By means of heat treatment of the whole polymer solution under the specific shearing force, the phase separation time can be further reduced, and the material consumption and energy consumption can be lowered.

[0048] According to the present application, the shearing force satisfies the above formula, when the shearing force is 0.3*μ 2 / (D 2 *ρ), there is a problem that the disturbance is not enough to make the polymer chain fully stretch and thus the phase separation is slow or the phase separation effect is poor; in addition, when the shearing force is 1000*μ 2 / (D 2 *ρ, there is a problem that the disturbance is too large to damage the phase interface.

[0049] According to the present application, the shear force can be achieved by means commonly used in the art to generate shear forces, preferably by means of a stirrer, that is, preferably the heat treatment of the polymer solution is carried out under stirring. The stirrer can be any form of stirrer, preferably one or more of a paddle stirrer, an anchor stirrer, a helical ribbon stirrer and a gate stirrer. The stirrer can be one or more.

[0050] In addition, the stirrer can be inserted into the phase separation vessel in a central top entry, an eccentric top entry, a bottom entry, a side entry, an inclined entry, etc. In addition, the sealing of the stirrer can include a mechanical seal, a packing seal, a magnetic seal, etc.

[0051] In a preferred embodiment of the present application, one or more baffles or draft tubes can be placed in the phase separation vessel to enhance the stirring effect.

[0052] According to the present application, the polymer solution can be any polymer solution commonly used in the art for heat treatment of a phase separation, for example, the polymer solution can be a polymer solution obtained by solution polymerization, for example, a homogeneous liquid polymerization system contained in a reactor; or a polymer solution obtained by dissolving a polymer in a liquid, such as an inert solvent or one or more monomers or a blend thereof, preferably a polymer solution obtained by solution polymerization.

[0053] According to the present application, the solution polymerization is a "polymerization reaction in solution state by dissolving monomers in a suitable solvent and adding an initiator (or catalyst)", commonly used in the art, as catalyst, for example, a Ziegler-Natta catalyst, a transition metal single-site or multi-site catalyst, a rare earth metal catalyst, etc. The catalyst can be soluble in the solvent or suspended in the solvent. In some embodiments, the catalyst can be used with an electron donor. In other embodiments, the catalyst needs to be used with a cocatalyst, such as a boron-containing compound and / or an alkyl aluminum and / or a methylaluminoxane.

[0054] According to the present application, the solution polymerization temperature can vary in a wide range, preferably between 45-200°C. The solution polymerization pressure can vary in a wide range, preferably between 0.5-15 MPa. The solution polymerization process can be batch, semi-continuous or continuous.

[0055] According to the present application, the concentration of the polymer in the polymer solution can vary in a wide range, preferably, the concentration of the polymer in the polymer solution is 5-20 wt%, more preferably, the concentration of the polymer in the polymer solution is 6-15 wt%.

[0056] According to the present application, preferably, the polymer in the polymer solution is selected from one or more of a plastic, a rubber and a thermoplastic elastomer.

[0057] As the plastic, for example, one or more of polyethylene, polypropylene, polybutylene, copolymers of ethylene with one or more a-olefins and copolymers of propylene with one or more a-olefins can be selected.

[0058] As the rubber, for example, one or more of butadiene-styrene rubber, butadiene rubber, isoprene rubber and styrene-isoprene rubber can be selected.

[0059] As the thermoplastic elastomer, for example, one or more of copolymers of ethylene with one or more a-olefins, copolymers of propylene with one or more a-olefins, copolymers of ethylene with one or more cyclic olefins, copolymers of ethylene and a-olefins with one or more cyclic olefins, copolymers of ethylene and a-olefins with optionally non-conjugated dienes, butene-ethylene copolymers, styrene-butadiene-styrene block copolymers and hydrogenated styrene-butadiene-styrene block copolymers can be selected.

[0060] As the copolymer of ethylene with one or more a-olefins, a copolymer based on ethylene is meant, which has a density in the range of about 0.85 - 0.915 g / cm3, preferably 0.88 - 0.91 g / cm3, more preferably 0.89 - 0.90 g / cm3, most preferably 0.89 - 0.90 g / cm3. 3 (determined according to ASTM D4703 method B and ASTM D1505). The copolymers based on ethylene described herein are copolymers containing at least about 50 wt% of ethylene derived units and higher a-olefin derived units, such as propylene, 1-butene, 1-hexene and 1-octene.

[0061] As the copolymer of propylene with one or more a-olefins, a copolymer based on propylene is meant. The copolymers based on propylene described herein are copolymers containing at least about 50 wt% of propylene derived units and ethylene derived units, or copolymers containing at least about 50 wt% of propylene derived units and higher a-olefin derived units, such as 1-butene, 1-hexene and 1-octene.

[0062] In a preferred embodiment of the present application, the copolymer of ethylene with one or more a-olefins is EPR, ethylene-1-butene copolymer elastomer or ethylene-1-octene copolymer elastomer.

[0063] According to the present application, preferably, the solvent in the polymer solution is selected from one or more of C5-C10 linear or branched alkyl, C5-C10 cycloalkane and C6-C20 aromatic hydrocarbon; more preferably, the solvent in the polymer solution is selected from one or more of n-pentane, i-pentane, cyclopentane, n-hexane, i-hexane, cyclohexane, methylcyclohexane, n-heptane, 2-methylheptane, n-octane, i-octane, mixed octane, benzene, toluene, o-xylene, m-xylene and p-xylene

[0064] In some preferred embodiments of the present application, a solution polymerization is carried out in an alkane such as isopentane, n-pentane, n-hexane, cyclohexane, isohexane using a metallocene catalyst and a boron-containing compound and / or a methylaluminoxane compound as a catalyst system, optionally an alkylaluminum compound as a scavenger to produce a polymer solution of a polymer that is an ethylene-α-olefin copolymer, a propylene-α-olefin copolymer, an ethylene-propylene copolymer with an optional non-conjugated diene. In more preferred embodiments, a solution polymerization is carried out in an alkane such as isopentane, n-pentane, or n-hexane using a metallocene catalyst and a boron-containing compound as a catalyst system, an alkylaluminum compound as a scavenger to produce a polymer solution of a polymer that is an ethylene-α-olefin copolymer. In still more preferred embodiments, a solution polymerization is carried out in an alkane such as isopentane, n-pentane, or n-hexane using a metallocene catalyst and a boron-containing compound as a catalyst system, an alkylaluminum compound as a scavenger to produce a polymer solution of a polymer that is a propylene-α-olefin copolymer.

[0065] In some preferred embodiments of the present application, a solution polymerization is carried out in an alkane such as isopentane, n-pentane, n-hexane, cyclohexane, isohexane using a non-metallocene catalyst and a boron-containing compound and / or a methylaluminoxane compound as a catalyst system, optionally an alkylaluminum compound as a scavenger to produce a polymer solution of a polymer that is an ethylene-α-olefin copolymer, a propylene-α-olefin copolymer, an ethylene-propylene copolymer with an optional non-conjugated diene. In more preferred embodiments, a solution polymerization is carried out in an alkane such as isopentane, n-pentane, n-hexane using a non-metallocene catalyst and a boron-containing compound and a methylaluminoxane as a catalyst system to produce a polymer solution of a polymer that is an ethylene-propylene copolymer with a non-conjugated diene.

[0066] In one specific embodiment of the present application, the polymer in the polymer solution is a polyolefin elastomer and the solvent in the polymer solution is a mixture of cyclohexane and n-hexane.

[0067] In one specific embodiment of the present application, the polymer in the polymer solution is a polyolefin elastomer and the solvent in the polymer solution is a mixture of cyclohexane and n-hexane.

[0068] In one specific embodiment of the present application, the polymer in the polymer solution is a polyolefin elastomer and the solvent in the polymer solution is n-pentane.

[0069] In one specific embodiment of the present application, the polymer in the polymer solution is a polyolefin elastomer and the solvent in the polymer solution is isopentane.

[0070] In another specific embodiment of the present application, the polymer in the polymer solution is a propylene-based elastomer, and the solvent in the polymer solution is n-pentane.

[0071] In another specific embodiment of the present application, the polymer in the polymer solution is a propylene-based elastomer, and the solvent in the polymer solution is iso-pentane.

[0072] In another specific embodiment of the present application, the polymer in the polymer solution is a polybutadiene rubber, and the solvent in the polymer solution is a mixture of cyclohexane and n-hexane.

[0073] In another specific embodiment of the present application, the polymer in the polymer solution is an ethylene-propylene rubber, and the solvent in the polymer solution is a mixture of cyclohexane and n-hexane.

[0074] According to the present application, the temperature of the heat treatment can be in the range of ± 50°C of the lower critical solution temperature of the polymer solution; preferably, the temperature of the heat treatment is in the range of - 50°C of the lower critical solution temperature of the polymer solution.

[0075] In the present application, by performing the heat treatment under the action of shear force, the solution phase separation temperature is reduced compared to the prior art which only performs phase separation by heat treatment, thus, in the present application, the heat treatment can be performed under conditions less than the lower critical solution temperature of the polymer solution, and the polymer solution phase separation time can be reduced, and the material consumption and energy consumption can be reduced.

[0076] The temperature of the heat treatment can be, for example, in the range of ± 50°C of the lower critical solution temperature of the polymer solution; preferably, the temperature of the heat treatment is in the range of - 50°C of the lower critical solution temperature of the polymer solution; more preferably, the temperature of the heat treatment is in the range of - 30°C of the lower critical solution temperature of the polymer solution; further preferably, the temperature of the heat treatment is in the range of - 20°C of the lower critical solution temperature of the polymer solution.

[0077] In this context, the "range of the lower critical solution temperature of the polymer solution ± 50℃" refers to the lower critical solution temperature of the polymer solution - 50℃ to the lower critical solution temperature of the polymer solution + 50℃; the "range of the lower critical solution temperature of the polymer solution - 50℃" refers to the lower critical solution temperature of the polymer solution - 50℃ to the lower critical solution temperature of the polymer solution; the "range of the lower critical solution temperature of the polymer solution - 30℃" refers to the lower critical solution temperature of the polymer solution - 30℃ to the lower critical solution temperature of the polymer solution; and the "range of the lower critical solution temperature of the polymer solution - 20℃" refers to the lower critical solution temperature of the polymer solution - 20℃ to the lower critical solution temperature of the polymer solution. Since the types of specific polymer solutions are different, the lower critical solution temperatures of specific polymer solutions are also different, and therefore the ranges of different types of polymer solutions are also different.

[0078] The lower critical solution temperature of the polymer solution is well known in the art, for example, it can be determined by turbidity method, and can be found in "Macromolecular Solution", Wu Qi, Higher Education Press, 2021, pp. 424-431.

[0079] According to the present application, the heat treatment can be carried out in a container that can generally perform heat treatment phase separation in the art, for example, the phase separation container can be any high temperature and high pressure resistant closed container, such as vertical, horizontal, rectangular, etc., the head form can be flat head, oval head, conical bottom, etc., which can be provided with a jacket with a heat conducting medium such as heat conducting oil, steam, or without a jacket.

[0080] According to the present application, as described above, the heat treatment temperature and pressure can be selected according to the lower critical solution temperature of the polymer solution, but generally, the temperature of the heat treatment can be 100-300℃, and the pressure of the heat treatment can be 2-50bar. In addition, the heat treatment temperature is more preferably 120-280℃, and further preferably 120-180℃; the pressure of the heat treatment is more preferably 3-20bar, and further preferably 3-10bar.

[0081] According to the present application, preferably, after phase separation by the present application, the polymer concentration in the clear liquid phase is less than 1wt%, and the polymer concentration in the concentrated liquid phase is 8-50wt%.

[0082] Specifically, the polymer concentration in the concentrated liquid phase is more than 1.35 times, more preferably more than 1.8 times, and further preferably more than 2.0 times of the polymer concentration in the polymer solution. In addition, it is preferably less than 10 times, more preferably less than 5 times, further preferably less than 4 times, and more further preferably less than 3.5 times.

[0083] The present application also provides a method for phase separation of a polymer solution, wherein the method comprises the steps of,

[0084] 1) a step of facilitating phase separation of a polymer solution by using the method for facilitating phase separation of a polymer solution according to the present application;

[0085] 2) a step of separating the supernatant phase and the concentrated phase.

[0086] According to the present application, the method for phase separation is not particularly limited and various methods for separating the supernatant phase and the concentrated phase commonly used in the art can be used.

[0087] According to a third aspect of the present application, there is provided a method for producing an olefin polymer, wherein the method comprises the steps of,

[0088] (A) feeding a catalyst system into a polymerization reactor, and contacting with one or more olefin monomers, optionally hydrogen, to perform olefin polymerization, thereby obtaining a polymerization reaction mixture;

[0089] (B) performing phase separation of the polymerization reaction mixture of step A by using the method for phase separation of a polymer solution according to the present application.

[0090] The method for producing an olefin polymer according to the present application is mainly improved in that the polymerization reaction mixture obtained by polymerization is subjected to phase separation, and the monomers, solvents, post-treatment methods and conditions used for polymerization can use various monomers, solvents, post-treatment methods and conditions commonly used in the art.

[0091] For example, the olefin monomers can be ethylene, propylene, butene, pentene, octene, butadiene, isoprene and styrene, etc.

[0092] In a preferred embodiment of the present application, step A comprises feeding a catalyst system into a polymerization reactor, and contacting with one or more olefin monomers of ethylene and / or propylene, optionally one or more comonomers, and optionally hydrogen, to perform olefin polymerization, thereby obtaining a polymerization reaction mixture.

[0093] As the comonomer, for example, 1-butene, 1-hexene and 1-octene, etc. can be mentioned.

[0094] As the olefin polymer, for example, one or more of the above-mentioned plastics, rubbers and thermoplastic elastomers can be mentioned.

[0095] According to the present application, by performing heat treatment under a specific Reynolds number condition, compared with the prior art which only performs phase separation by heat treatment, the solution phase separation temperature is reduced, the solution phase separation time is reduced, and the material consumption and energy consumption of the whole process can be reduced by about 20-40% respectively compared with the prior art.

[0096] The present application will be described in detail below by way of examples, but the present application is not limited to the following examples.

[0097] Unless otherwise specified, the operation and processing method involved in the present application belongs to the conventional method in the art.

[0098] Unless otherwise specified, the instrument used in the present application is the conventional instrument in the art.

[0099] Unless otherwise specified, the various raw materials used are commercially available.

[0100] In the examples and comparative examples, ethylene-propylene rubber (EPR), polybutadiene rubber (PB), propylene-based elastomer (PBE) or polyolefin elastomer (POE) is used as an example, and the solvent is n-pentane (nPN), isopentane (iPN), n-hexane (nHX), cyclohexane and a mixture of n-hexane (HX, the weight percentage of n-hexane is 80%).

[0101] POE is an ethylene / octene copolymer prepared using (tert-butylamido)dimethyl(1,2,3,4,5-η)-1,5,6,7-tetrahydro-2-methylindenylsilane titanium (II) 1,3-pentadiene metal complex (prepared according to USP 5,965,756) and tris(pentafluorophenyl)borane cocatalyst and triisobutylaluminum scavenger at a molar ratio of Ti:B:Al of 1:3:1, with a density of 0.868 g / cm 3 , a weight average molecular weight of 130,000, a molecular weight distribution of 2.0 and an ethylene mass fraction of 60-62%.

[0102] PBE is a propylene / ethylene copolymer prepared using dimethylsilanediyl(5,6,7,8-tetrahydro-2,5,5,8,8-pentamethylbenzoindenyl) hafnium dimethyl (prepared according to US60 / 586465) and commercially available triphenylcarbenium tetrakis(pentafluorophenyl)borate and triisobutylaluminum scavenger at a molar ratio of Hf:B:Al of 1:2:1, with a density of 0.87 g / cm 3 , a weight average molecular weight of 120,000, a molecular weight distribution of 2.1 and an ethylene mass fraction of 12-15%.

[0103] EPR is an ethylene / propylene copolymer prepared using bis((2-oxo-3-(dibenzo-1H-pyrrol-1-yl)-5-(methyl)phenyl)-2-phenoxy)-1,3-propanediyl zirconium (IV) dichloride (prepared according to CN102786619B) and commercially available methylaluminoxane solution at a molar ratio of Zr:B:Al of 1:2:1, with a density of 0.87 g / cm 3 , a weight average molecular weight of 120,000 and a molecular weight distribution of 2.1.

[0104] The PB was prepared according to the method of Example 1 of CN1093375A, and the weight average molecular weight of the polybutadiene rubber obtained was 390,000, and the molecular weight distribution was 3.8.

[0105] In the following examples, the amount of glue solution entering the heated tank with stirring paddle was 3.1 L. The dynamic device for providing shear force was a four-leaf inclined paddle stirrer, and the inclination angle of the paddle was 45 degrees, and the paddle diameter was 0.05 mm. The heated tank served as a phase separation container, and the inner diameter of the tank was 0.15 m.

[0106] Examples 1-17 and Comparative Examples 1-4

[0107] The polymer solution was transported to the phase separation heated tank by a gear pump, and when the pressure in the phase separation heated tank increased to the required pressure, the temperature began to rise and stir, and when the temperature was higher than 110℃, every 5℃ increase in heating was observed for 10 minutes to observe whether there was a phase separation trend, and during the heating, the pressure was kept constant, and when the temperature reached the phase separation trend, the time was started to be counted, and after the phase separation was completed, samples were taken from the upper and lower parts respectively, poured into three times the amount of ethanol, and the precipitated polymer was taken out and dried at 80℃ for 24 hours, weighed, and the glue solution concentration was calculated.

[0108] The density of the polymer solution was tested as follows: using a 100 ml pressure-resistant steel bottle for sampling, weighing and subtracting the weight of the empty steel bottle to obtain the weight of the polymer solution, and then dividing by the volume of the steel bottle to obtain the density of the polymer solution. The viscosity and shear rate of the polymer solution under experimental conditions were tested on a rotational rheometer HAAKE RS6000 (Thermo Fisher Scientific, USA). The Reynolds number Re was calculated by the formula Re = d 2 *N*ρ / μ, where d is the diameter of the stirrer, in meters; N is the rotational speed; μ is the viscosity of the polymer solution before phase separation, in Pa*s; and ρ is the density of the polymer solution before phase separation, in kg / m 3 . The shear force τ was calculated by the formula τ = μ*Vs, where μ is the viscosity of the polymer solution before phase separation, in Pa*s; and Vs is the shear rate.

[0109] In addition, the conditions of the examples are shown in Table 1. The operation steps of the comparative examples are generally similar to those of the examples, except that the stirring is different, and the conditions are also shown in Table 1.

[0110] Table 1

[0111]

[0112] By comparing Examples 1-17 and Comparative Examples 1-2, it can be seen that the Reynolds number is in the range of 0.02-30, and the shear force is in the range of 0.3*μ 2 / (D 2*ρ)<τ<1000*μ 2 / (D 2 *ρ) range, compared with the prior art of phase separation by heat treatment only, the solution phase separation time is reduced, the material consumption and energy consumption of the whole process are significantly reduced.

[0113] By comparing Example 1-3 and Comparative Example 1, and Example and Comparative Example 2, it is known that when the Reynolds number is in the range of 0.02-30, and the shear force is in the range of 0.3*μ 2 / (D 2 *ρ)<τ<1000*μ 2 / (D 2 *ρ) range, compared with the prior art of phase separation by heat treatment only, not only the solution phase separation time is reduced, the material consumption and energy consumption of the whole process are significantly reduced, and the polymer concentration of the concentrated phase is improved.

[0114] By comparing Example 11 and Comparative Example 3, it is known that when the Reynolds number is in the range of 0.02-30, and the shear force is in the range of 0.3*μ 2 / (D 2 *ρ)<τ<1000*μ 2 / (D 2 *ρ) range, compared with the shear force and Reynolds number not in the above range, not only the solution phase separation time is reduced, the material consumption and energy consumption of the whole process are significantly reduced, and the polymer concentration of the concentrated phase is improved.

[0115] By comparing Example 16 and Comparative Example 4, it is known that when the Reynolds number is in the range of 0.02-30, and the shear force is in the range of 0.3*μ 2 / (D 2 *ρ)<τ<1000*μ 2 / (D 2 *ρ) range, the polymer solution can be phase separated in a short time, and when the shear force and Reynolds number exceed the range, the polymer solution cannot be phase separated.

[0116] As known from the above, the method provided by the present application can reduce the phase separation temperature and the phase separation time when phase separating the polymer solution, thereby reducing the energy consumption and the steam consumption compared with the prior art, thereby greatly reducing the production cost, and the polymer concentration of the concentrated phase can be provided.

[0117] The preferred embodiments of the present application are described in detail above, but the present application is not limited to the specific details in the above embodiments, and various simple modifications can be made to the technical solutions of the present application within the technical concept of the present application, and these simple modifications all belong to the protection scope of the present application.

[0118] It should be further noted that the various technical features described in the above specific embodiments can be combined in any suitable manner, and in order to avoid unnecessary repetition, the various possible combinations of features are not all listed here. In addition, any combination of the various embodiments of the present application can also be made, as long as it does not deviate from the spirit of the present application, and it should also be considered as disclosed by the present application.

Claims

1. A method of facilitating phase separation of a polymer solution, characterized by, The method comprises: subjecting at least part of the polymer solution to a thermal treatment under flow so that the polymer solution separates into a dilute phase and a concentrated phase, wherein the Reynolds number Re of the polymer solution flow is between 0.02 and 30, the thermal treatment of the polymer solution is carried out under stirring, The Reynolds number Re is calculated by the formula Re = d 2 *N*ρ / μ, where d is the diameter of the stirrer in m, N is the rotational speed, μ is the viscosity of the polymer solution before phase separation in Pa*s and p is the density of the polymer solution before phase separation in kg / m 3 , and subjecting at least part of the polymer solution to a thermal treatment under shear stress so that the polymer solution separates into a dilute phase and a concentrated phase, wherein the shear stress τ satisfies the following formula, 0.3*μ 2 / (D 2 *ρ)<τ<1000*μ 2 / (D 2 *ρ) wherein μ is the viscosity of the polymer solution before phase separation, in Pa*s, D is the diameter of the phase separation vessel, in m, p is the density of the polymer solution before phase separation, in kg / m3 3 ; the shear stress τ is calculated by the formula τ = μ * Vs, wherein μ is the viscosity of the polymer solution before phase separation, in Pa*s, and Vs is the shear rate.

2. The method of claim 1, wherein, τ satisfies the following formula: 20*μ 2 / (D 2 *ρ)<τ<120*μ 2 / (D 2 *ρ).

3. The method of claim 1, wherein, subjecting the entire polymer solution to a thermal treatment under shear stress.

4. The method of any of claims 1-3, wherein, The polymer solution is a polymer solution obtained by solution polymerization.

5. The method of any of claims 1-3, wherein, The concentration of the polymer in the polymer solution is between 5 and 20 wt%.

6. The method of claim 5, wherein, The concentration of the polymer in the polymer solution is between 6 and 15 wt%.

7. The method of any of claims 1-3, wherein, The polymer in the polymer solution is selected from one or more of a plastic, a rubber and a thermoplastic elastomer.

8. The method of claim 7, wherein, The plastic is selected from one or more of polyethylene, polypropylene, polybutylene, a copolymer of ethylene and one or more α-olefins and a copolymer of propylene and one or more α-olefins.

9. The method of claim 7, wherein, The rubber is selected from one or more of a butadiene-styrene rubber, a butadiene rubber, an isoprene rubber and a styrene-isoprene rubber.

10. The method of claim 7, wherein, The thermoplastic elastomer is selected from one or more of a copolymer of ethylene and one or more α-olefins, a copolymer of propylene and one or more α-olefins, a copolymer of ethylene and one or more cyclic olefins, a copolymer of ethylene and α-olefins and one or more cyclic olefins, a copolymer of ethylene and α-olefins and a non-conjugated diene, a styrene-butadiene-styrene block copolymer and a hydrogenated styrene-butadiene-styrene block copolymer.

11. The method of claim 7, wherein, The thermoplastic elastomer is a butene-ethylene copolymer.

12. The method of any one of claims 1-3, wherein, The solvent in the polymer solution is selected from one or more of a C5-C10 straight-chain or branched alkane, a C5-C10 cycloalkane and a C6-C20 aromatic hydrocarbon.

13. The method of any of claims 1-3, wherein, The solvent in the polymer solution is selected from one or more of n-pentane, i-pentane, cyclopentane, n-hexane, i-hexane, cyclohexane, methylcyclohexane, n-heptane, 2-methylheptane, n-octane, mixed octane, benzene, toluene, o-xylene, m-xylene and p-xylene.

14. The method of any one of claims 1-3, wherein, The temperature of the thermal treatment is in the range of the lower critical solution temperature of the polymer solution ± 50°C.

15. The method of claim 14, wherein, The temperature of the thermal treatment is in the range of the lower critical solution temperature of the polymer solution - 50°C.

16. The method of any one of claims 1-3, wherein, The thermal treatment is carried out in a phase separation tank.

17. The method of claim 16, wherein, The polymer solution is subjected to the thermal treatment under stirring in the phase separation tank.

18. The method of any of claims 1-3, wherein, The temperature of the thermal treatment is between 100 and 300°C and the pressure of the thermal treatment is between 10 and 50 bar.

19. The method of any of claims 1-3, wherein, The concentration of the polymer in the dilute phase is less than 1 wt% and the concentration of the polymer in the concentrated phase is between 8 and 50 wt%.

20. The method of claim 18, wherein, The concentration of the polymer in the concentrated phase is more than 1.35 times the concentration of the polymer in the polymer solution.

21. The method of claim 20, wherein, The polymer concentration in the concentrated phase is more than 1.8 times the polymer concentration in the polymer solution.

22. The method of claim 21, wherein, The polymer concentration in the concentrated phase is more than 2.0 times the polymer concentration in the polymer solution.

23. A method of polymer solution phase separation, characterized in that, The method comprises the following steps, 1) a step of facilitating phase separation of a polymer solution using the method of facilitating phase separation of a polymer solution according to any one of claims 1-22; 2) a step of separating the supernatant phase and the concentrated phase.

24. A process for the preparation of an olefin polymer, characterized by, The method comprises the following steps, (A) feeding the catalyst system into a polymerization reactor to contact with one or more olefin monomers, optionally hydrogen, to carry out olefin polymerization to obtain a polymerization reaction mixture; (B) phase separating the polymerization reaction mixture of step A using the method of phase separation of a polymer solution according to claim 23.

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