Method for preparing poly-1-butene

Abstract

The present invention relates to the technical field of olefin polymerization, and discloses a method for preparing poly-1-butene, which comprises: in the presence of a catalyst system, polymerizing 1-butene and an optional comonomer in a C2-C4 inert solvent to obtain a polymer-containing solution, collecting the gas volatilized during the polymerization process for condensation to obtain a condensate and a non-condensable gas, the condensate is returned to the polymerization step, and optionally, the non-condensable gas is returned to the polymerization step after compression and supercharging. The method of the present invention can not only achieve a high catalyst yield, but also obtain a poly-1-butene product with excellent performance; at the same time, the production capacity of the reactor can be greatly improved, and the volatile component content (VOC) content in the final product does not exceed 300ppm.

Description

Technical Field

[0001] The invention relates to the technical field of olefin polymerization, in particular to a method for preparing poly-1-butene. Background Art

[0002] Polybutene-1 is a well-known polymer in the art and is very suitable for the fields of pipes, films, and blending and modification. The preparation process of polybutene-1 is basically the same as that of polypropylene. At present, the production processes of polybutene-1 reported in the literature include slurry polymerization process, homogeneous polymerization process (including bulk polymerization and solution polymerization) and gas phase polymerization.

[0003] The yield of poly-1-butene obtained by the slurry butene-1 polymerization process is low and the product performance is poor. This may be because poly-1-butene is easily soluble in organic solvents or liquid butene-1 monomers, especially above 40°C, and the solubility increases with increasing temperature, which causes the adhesion of poly-1-butene particles. If the particle adhesion is to be avoided, the reaction temperature must be lowered to reduce the solubility of poly-1-butene in organic solvents or liquid butene-1, but this will lead to a decrease in the yield of poly-1-butene, and at the same time, the isotactic index of the obtained polymer is reduced, and the ash content is high, so that its performance deteriorates.

[0004] CN200610170962 discloses a method for preparing poly 1-butene by liquid phase bulk segmented polymerization. In this method, the catalyst is added to the reactor after low-temperature prepolymerization. The reaction temperature is 30-70°C. After the reaction, ethanol is added to inactivate the active components. The polymer obtained by this method is in a granular state with an isotacticity of 94-99%. Although the polymer obtained by this preparation method has a very high isotactic index, it still cannot completely solve the problem of polymer particle adhesion.

[0005] CN2007100113587 and CN201010198121 disclose a method for preparing highly isotactic poly-1-butene, which adopts a bulk precipitation synthesis process with a reaction temperature of 0-70°C. The obtained polymer is powdery particles with an isotacticity of 80-98%, but the catalyst yield is less than 5kgPB-1 / (gCat·3h).

[0006] CN201210417622 discloses a method for preparing highly isotactic poly-1-butene, in which the catalyst is prepolymerized in a low-temperature slurry and then added to a reactor. The reaction temperature is 30-60°C. The obtained polymer has a good particle morphology and an isotacticity of 96-98%. However, the catalyst yield is less than 3.5 kgPB-1 / (gCat·h), and the problem of polymer particle adhesion is not solved.

[0007] In the homogeneous polymerization process, since the viscosity of poly-1-butene increases greatly after being dissolved in a liquid medium, the heat transfer and mass transfer efficiency decreases. The common methods of precooling the raw materials or circulating the polymer solution externally are used to improve the heat removal capacity of the polymerization reactor, thereby increasing its yield. This makes the process more complicated and increases the construction cost and production cost of the device.

[0008] Therefore, it is difficult to prepare poly-1-butene by slurry polymerization process, while homogeneous polymerization process is more complicated and has higher production cost. Gas phase polymerization yield is lower than slurry polymerization process, and there is no industrial application yet.

[0009] CN99800235 discloses a method for gas phase polymerization of 1-butene using a ZN catalytic system, wherein the polymerization is carried out in a first gas phase reactor (60° C.) for 11 hours, with a yield of about 1.4 kg PB-1 / gCat, and then the polymerization is carried out in a second gas phase reactor at 70° C. for 9 hours, with a yield of about 5.0 kg PB-1 / gCat. As a result of the low yield of the catalyst, the gas phase 1-butene polymerization process has not yet achieved commercial production. Summary of the invention

[0010] The purpose of the present invention is to overcome the above technical problems in the prior art and provide a method for preparing poly-1-butene.

[0011] In order to achieve the above-mentioned object, the present invention provides a method for preparing poly 1-butene, which comprises: in the presence of a catalyst system, polymerizing 1-butene and an optional comonomer in a C2-C4 inert solvent to obtain a polymer-containing solution, collecting and condensing gases volatilized during the polymerization to obtain condensate and non-condensable gases, returning the condensate to the polymerization step, and optionally, returning the non-condensable gases to the polymerization step after being compressed and pressurized.

[0012] The method of the present invention can not only achieve high catalyst yield, but also obtain poly 1-butene products with excellent performance; at the same time, it can also greatly improve the production capacity of the reactor, and the volatile component content (VOC) content in the final product does not exceed 300ppm.

[0013] In particular, using ethane as an inert solvent can further increase the yield of poly-1-butene, reduce the volatile content in poly-1-butene, and also ensure the isotacticity and melt mass flow rate of poly-1-butene. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 The present invention provides a process flow chart for preparing poly 1-butene according to an embodiment of the present invention.

[0015] Description of Reference Numerals

[0016] R1 pre-complexation reactor R2 first reactor

[0017] R3 Second Reactor E1 First Cooler

[0018] E2 Second cooler P1 First compression pump

[0019] P2 second compression pump DETAILED DESCRIPTION

[0020] The endpoints and any values ​​of the ranges disclosed in this article 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 endpoint values ​​of each range, the endpoint values ​​of each range and the 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 as specifically disclosed in this article.

[0021] In the present invention, "ppm" means molar concentration. "MPag" means "gauge pressure", and usually "positive pressure" is expressed as "gauge pressure". "MPaA" or "kPaA" means "absolute pressure", and usually "negative pressure" is expressed as "absolute pressure".

[0022] In the present invention, "1-butene", "butene-1" and "butene" can be interchanged with each other.

[0023] The present invention provides a method for preparing poly 1-butene, which comprises: in the presence of a catalyst system, polymerizing 1-butene and an optional comonomer in a C2-C4 inert solvent to obtain a polymer-containing solution, collecting and condensing gases volatilized during the polymerization to obtain condensate and non-condensable gases, returning the condensate to the polymerization step, and optionally, returning the non-condensable gases to the polymerization step after being compressed and pressurized.

[0024] In the present invention, the "condensate" and "non-condensable gas" are mixtures of 1-butene, C2-C4 inert solvent and optional comonomers. When hydrogen is introduced during the polymerization process, the "condensate" and "non-condensable gas" also contain hydrogen.

[0025] According to the present invention, the condensation conditions can be selected within a wide range. Preferably, the condensation conditions are such that the polymerization temperature is 40-100°C, preferably 50-80°C; the polymerization pressure is 1-5MPag, preferably 2-4MPag.

[0026] According to the present invention, preferably, the condensation temperature is lower than 50° C. The condensing agent used in the condensation process is not limited as long as it can meet the condensation temperature. The condensing agent can be a single type of condensing agent, such as water, or a mixture of two or more types of condensing agents.

[0027] According to the present invention, the polymerization time can be selected within a wide range. Preferably, the polymerization time is such that the polymer content in the polymer-containing solution is 0.1-50wt%, preferably 15-35wt%; more preferably, the polymerization time is 0.5-12h, preferably 3-8h.

[0028] According to the present invention, preferably, hydrogen is introduced during the polymerization process to adjust the molecular weight of the polymer, and more preferably, the molar ratio of 1-butene to hydrogen is 1:0.00001-0.02.

[0029] According to the present invention, preferably, the molar ratio of 1-butene to the C2-C4 inert solvent is 1:0.1-3, preferably 1:0.5-2.

[0030] According to the present invention, preferably, the C2-C4 inert solvent is at least one of ethane, propane, n-butane and isobutane, preferably ethane.

[0031] According to the present invention, preferably, the 1-butene is liquid 1-butene.

[0032] According to the present invention, preferably, the comonomer is at least one of ethylene and / or an α-olefin having 3 to 10 carbon atoms, such as propylene, 1-hexene and 1-octene.

[0033] According to the present invention, preferably, the preparation method of the catalyst system is: subjecting the catalyst, the co-catalyst and the external electron donor to a complex reaction at a mass ratio of 1:1-100:0.1-20 at 5-30°C; preferably, the temperature of the pre-complex reaction is 5-20°C; more preferably, the time of the pre-complex reaction is 5-30min, preferably 5-15min.

[0034] According to the present invention, the method for obtaining the catalyst is not particularly limited, and the catalyst can be obtained by purchase or prepared according to the method in the literature. Preferably, the catalyst is prepared by referring to the method in the prior art, for example, CN85100997, CN93102795.0, CN200810117894, CN98126383.6, CN98111780.5, CN98126385.2, CN00109216.2, CN99125566.6, CN99125567.4, CN02100900.7, CN102453162, CN10 3819586, CN104610474, CN104610475, CN104610476, CN104610477, CN104610478, CN105622800, CN106543314, CN106543313, CN106543312, CN106543310, CN106554439, CN107522800, CN107522803; more preferably, the catalyst is prepared by the method of CN85100997, CN93102795.0, CN200810117894.

[0035] According to the present invention, preferably, the co-catalyst is an organic aluminum compound, which can be selected from n X (3-n) An alkyl aluminum compound of the structure, wherein R is an alkyl group, aralkyl group, aryl group, etc. having 1 to 20 carbon atoms, X is a halogen, and n is an integer of 0 to 3, for example, at least one of trimethylaluminum, triethylaluminum, triisobutylaluminum, trihexylaluminum, tri-n-butylaluminum, diethylaluminum monochloride, monoethylaluminum dichloride, dimethylaluminum monochloride, diisobutylaluminum monochloride, diisobutylaluminum dichloride, tri(2-methyl-3-phenyl-butyl)aluminum and tri(2-phenyl-butyl)aluminum; and an aluminum compound selected from aluminoxanes, for example, at least one of methylaluminoxane, tetra(isobutyl)aluminoxane, tetra(2,4,4-trimethyl-pentyl)aluminoxane, tetra(2,3-dimethylbutyl)aluminoxane and tetra(2,3,3-trimethylbutyl)aluminoxane.

[0036] According to the present invention, preferably, the external electron donor is selected from at least one of alkoxysilanes, aminosilanes, organic amine compounds and ether compounds. More preferably, the external electron donor is tetramethoxysilane, tetraethoxysilane, trimethylmethoxysilane, trimethylethoxysilane, trimethylphenoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, methyl tert-butyldimethoxysilane, methylisopropyldimethoxysilane, diphenoxydimethoxysilane, dimethoxysilane At least one of phenyldiethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, vinyltrimethoxysilane, cyclohexylmethyldimethoxysilane, dicyclopentyldimethoxysilane, diisopropyldimethoxysilane, diisobutyldimethoxysilane, 2-ethylpiperidinyl-2-tert-butyldimethoxysilane, (1,1,1-trifluoro-2-propyl)-2-ethylpiperidinyldimethoxysilane and (1,1,1-trifluoro-2-propyl)-methyldimethoxysilane.

[0037] According to the present invention, in order to further improve the quality of poly-1-butene, preferably, the polymerization method includes:

[0038] (1) subjecting 1-butene and an optional comonomer to a first polymerization in a C2-C4 inert solvent in the presence of a catalyst system;

[0039] (2) mixing the product of the first polymerization with 1-butene and an optional comonomer to conduct a second polymerization;

[0040] (3) Optionally, the product of the second polymerization is mixed with 1-butene and an optional comonomer to conduct a third polymerization.

[0041] According to the present invention, preferably, the conditions of the first polymerization include: temperature of 40-100° C., preferably 50-80° C., pressure of 1-5 MPag, preferably 2-4 MPag, time of 0.5-4 h, preferably 1-2 h.

[0042] According to the present invention, preferably, hydrogen is introduced during the first polymerization process, and the molar ratio of 1-butene to hydrogen is 1:0.00001-0.02.

[0043] According to the present invention, preferably, the molar ratio of 1-butene and C2-C4 inert solvent introduced into the first polymerization process is 1:0.1-3, preferably 1:0.5-2.

[0044] According to the present invention, preferably, the conditions of the second polymerization include: temperature of 40-100° C., preferably 50-80° C., pressure of 1-5 MPag, preferably 2-4 MPag, time of 0-4 h, preferably 1-3 h.

[0045] According to the present invention, preferably, hydrogen is introduced during the second polymerization process, and the molar ratio of 1-butene to hydrogen is 1:0.00001-0.02.

[0046] According to the present invention, preferably, the molar ratio of 1-butene and C2-C4 inert solvent introduced into the second polymerization process is 1:0.1-3, preferably 1:0.5-2.

[0047] According to the present invention, preferably, the conditions of the third polymerization include: temperature of 40-100°C, preferably 50-80°C, pressure of 1-5 MPag, preferably 2-4 MPag, time of 0-4h, preferably 1-3h.

[0048] According to the present invention, preferably, hydrogen is introduced during the second polymerization process, and the molar ratio of 1-butene to hydrogen is 1:0.00001-0.02.

[0049] According to the present invention, preferably, the molar ratio of 1-butene and C2-C4 inert solvent introduced into the third polymerization process is 1:0.1-3, preferably 1:0.5-2.

[0050] In the present invention, at the initial stage of the polymerization reaction, since the introduced material is a liquid material (except hydrogen), there is no need to control the pressure, and the temperature can be controlled by condensation. As the reaction proceeds, the pressure of the polymerization system will increase. At this time, it is ensured that the pressure of the system meets the requirements of the first polymerization, the second polymerization and the third polymerization.

[0051] According to the present invention, preferably, the method further comprises devolatilizing and granulating the polymer-containing solution.

[0052] According to the present invention, the conditions of the devolatilization treatment can be selected within a wide range. In order to improve the quality of poly-1-butene, preferably, the devolatilization treatment temperature is 100-250°C, the pressure is 0.00001-4MPa, preferably 0.00001-3MPa, and the time is 10-120min, preferably 20-60min.

[0053] According to the present invention, preferably, the devolatilization treatment includes at least two devolatilization treatments, and the last devolatilization treatment is carried out under vacuum conditions, and the vacuum conditions refer to an absolute pressure of no higher than 10 kPaA.

[0054] According to the present invention, preferably, the granulation is carried out by underwater granulation.

[0055] According to the present invention, preferably, auxiliary agents need to be added during the granulation process, and the auxiliary agents include but are not limited to heat stabilizers, antioxidants, nucleating agents, light stabilizers and calcium stearate.

[0056] The heat stabilizer, antioxidant and light stabilizer in the present invention can be conventionally selected according to the prior art, and the conventional amount used in the art can be selected. For example, the heat stabilizer can be a solid heat stabilizer or a liquid heat stabilizer, preferably a solid heat stabilizer. The function of the heat stabilizer is to prevent the polymer from being thermally degraded during the granulation process, and commonly used heat stabilizers include hindered phenol heat stabilizers and / or phosphite heat stabilizers.

[0057] According to the present invention, preferably, the method further comprises inactivating the polymer-containing solution before the devolatilization treatment.

[0058] According to the present invention, preferably, the inactivation treatment comprises mixing a solution containing a polymer with an antioxidant and an inactivating agent.

[0059] According to the present invention, preferably, the antioxidant is at least one of hindered phenol antioxidants, hindered amine antioxidants, phosphite antioxidants and sulfide-containing antioxidants, and more preferably a combination of hindered phenol antioxidants and phosphite antioxidants.

[0060] According to the present invention, preferably, the antioxidant is added in an amount of 0.1-1% by weight of the polymer-containing solution.

[0061] According to the present invention, preferably, the inactivating agent is water and / or ethanol.

[0062] According to the present invention, preferably, the polymerization is carried out in a polymerization reactor, and the polymerization reactor comprises one or more vertical stirred reactors connected in series, and a condenser is arranged above each vertical stirred reactor;

[0063] The first vertical stirring reactor is used for homogeneous polymerization of 1-butene, and the second and subsequent vertical stirring reactors are used for mixing the reaction product of the previous vertical stirring reactor with 1-butene and optional comonomers for homogeneous polymerization to obtain a polymer-containing solution.

[0064] According to the present invention, preferably, the number of the vertical stirred reactors is 2-3.

[0065] According to the present invention, preferably, the condenser is arranged obliquely above the vertical stirred reactor; more preferably, the inclination angle is 0.01°-20°, more preferably, 1°-5°.

[0066] According to the present invention, preferably, the method is carried out in the following system, the system comprising a pre-complexing reactor, a polymerization reactor, a devolatilization device and a granulation device connected in sequence,

[0067] The pre-complexation reactor is used for pre-complexation reaction of the catalyst, the co-catalyst and the external electron donor; the devolatilization device is used for removing volatiles from the polymer-containing solution; and the granulation device is used for granulating the devolatilized polymer.

[0068] According to the present invention, preferably, the devolatilization device comprises at least two devolatilization devices connected in series.

[0069] According to the present invention, preferably, the pelletizing device is an underwater pelletizer.

[0070] In order to deepen the understanding of the method of the present invention, a preferred embodiment is provided (the schematic flow chart of which is shown in Figure 1 However, the embodiments do not limit the scope of the present invention.

[0071] according to Figure 1 To describe an embodiment of the present invention. A Ziegler-Natta catalyst 1, an alkyl aluminum 2 and an external electron donor 3 are added to a pre-complexing reactor R1 for a pre-complexing reaction. The product of the pre-complexing reactor is directly added to the first reactor R2, and at the same time, 1-butene 4, ethane 5, hydrogen 6 and a comonomer ethylene 7 are added to the first reactor R2 for a first polymerization reaction. The first reactor R2 contains gas and liquid phases. During normal operation, the liquid level of the first reactor R2 is controlled at about 60% by the first compression pump P1 at the bottom of the reactor while maintaining a stable feed amount. A gas phase discharge pipeline is provided at the top of the first reactor R2, and the discharge pipeline is connected to a first condenser E1 located above the first reactor R2. The outlet of the first condenser E1 is connected to the upper part of the first reactor R2. In order to facilitate the outflow of condensate, the first condenser E1 is placed obliquely. When 1-butene undergoes polymerization reaction in R2, a large amount of polymerization heat is released, so that a large amount of 1-butene / ethane in the first reactor R2 is vaporized and flows out from the top thereof, and the vaporized gas is condensed in the first condenser E1 and then returns to the first reactor R2 under the action of gravity, wherein the non-condensable gas is also returned to the first reactor R2 after being compressed and pressurized. In this way, the heat removal capacity of the first reactor R2 is greatly improved (at least by about 30%).

[0072] The polymer solution of the first reactor R2 flows out from the bottom thereof, and is sent to the second reactor R3 after being pressurized by pump P1. 1-Butene 8, ethane 9, hydrogen 10 and comonomer ethylene 11 are also added to the second reactor R3 for the second polymerization reaction. The second reactor R3 is a two-phase gas and liquid reactor. During normal operation, the liquid level of the second reactor R3 is controlled at about 60% by the second compression pump P2 discharging from the bottom thereof while maintaining the feed amount stable; and a gas phase discharge pipeline is also provided at the top of the second reactor R3, which is connected to a second condenser E2 located above R3, and the outlet of the second condenser E2 is connected to the upper part of R3, and the second condenser E2 is also placed obliquely. When 1-butene undergoes polymerization reaction in R3, a large amount of polymerization heat is released, so that a large amount of 1-butene / ethane is vaporized and flows out from the top thereof, and the vaporized gas is condensed in E2, and then returns to R3 under the action of gravity, wherein the non-condensable gas is also returned to the second reactor R3 after being compressed and pressurized. Thus, the heat removal capacity of the second reactor R3 is greatly improved (at least 30%). The polymer solution in the second reactor flows out from the bottom thereof, and is pressurized by the second compression pump P2 and then sequentially subjected to deactivation treatment, devolatilization treatment and granulation.

[0073] The present invention will be described in detail below by way of examples. In the following examples,

[0074] The solvent in the triethylaluminum solution is hexane, and the concentration of triethylaluminum is 0.1 mmol / L.

[0075] The solvent in the diisopropyldimethoxysilane solution is hexane, wherein the concentration of diisopropyldimethoxysilane is 0.1 mmol / L.

[0076] Example 1

[0077] The catalyst was prepared according to the method described in Example 1 of CN85100997, with triethylaluminum solution as the co-catalyst and diisopropyldimethoxysilane solution as the external electron donor.

[0078] 0.06g / h of catalyst, 0.4g / h of triethylaluminum solution and 0.05g / h of diisopropyldimethoxysilane solution were continuously added to the pre-complexation reactor R1, the pre-complexation temperature was 10°C, the time was 10min, and the pressure was 2.7MPag. The pre-complexation product continuously flowed out from the bottom and entered the first reactor R2 (20L pressure-resistant stirred tank), and the materials added to the first reactor also included 5.0kg / h of a mixture of liquid 1-butene and liquid ethane (the molar ratio of 1-butene to ethane was 3:2) and 1.0g / h of hydrogen. The temperature of the condensate was controlled by adjusting the amount of cooling water added to the first condenser E1 (the tilt angle was 3°) at the top of R2, and then the polymerization temperature of the first reactor was controlled to be 65°C and the pressure to be 2.6MPag.

[0079] After 120 minutes of polymerization in the first reactor, the product in the first reactor continuously flows out from the bottom and is pressurized by the first compression pump P1 and then sent to the second reactor R3 (20L pressure-resistant stirred tank). At the same time, the materials added to the second reactor include 5.0 kg / h of a mixture of liquid 1-butene and liquid ethane (the molar ratio of 1-butene to ethane is 3:2) and 1.8 g / h of hydrogen. The temperature of the condensate is controlled by adjusting the amount of cooling water added to the second condenser E2 at the top of R3 (the inclination angle is 3°), and then the polymerization temperature of the second reactor is controlled to 65°C and the pressure to 2.6 MPag.

[0080] After 60 minutes of polymerization in the second reactor, the polymer-containing solution in the second reactor is continuously discharged from the bottom thereof, pressurized to 5 MPag by the second compression pump P2, and then sent to a static mixer. In the static mixer, the polymer-containing solution is fully mixed with an inactivator (water) and an antioxidant (a phosphite antioxidant, added in an amount of 0.4% of the weight of the polymer-containing solution), and then enters a devolatilization system. The devolatilization system is divided into two stages of devolatilization, wherein the first stage of devolatilization uses falling strip devolatilization to concentrate the polymer-containing solution, and the conditions of the falling strip devolatilization include a temperature of 180°C, a pressure of 0.05 MPag, and a time of 30 minutes to obtain a polymer melt having a polymer content greater than 90 wt%; the polymer melt is pressurized by a pump and heated by a heat exchanger, and then enters a secondary devolatilizer, and the secondary devolatilizer uses falling film devolatilization, and the conditions of falling film devolatilization include a temperature of 200°C, a pressure of 10 kPaA, and a time of 20 minutes to obtain a polymer melt.

[0081] The polymer melt at the bottom of the secondary devolatilizer is pumped to the granulation system by a gear pump for granulation.

[0082] Example 2

[0083] The catalyst was prepared according to the method described in Example 1 of CN85100997, with triethylaluminum solution as the co-catalyst and diisopropyldimethoxysilane solution as the external electron donor.

[0084] 0.06g / h of catalyst, 0.4g / h of triethylaluminum solution and 0.05g / h of diisopropyldimethoxysilane solution were continuously added to the pre-complexation reactor R1, the pre-complexation temperature was 20°C, the time was 15min, and the pressure was 2.6MPag. The pre-complexation product continuously flowed out from the bottom and entered the first reactor R2 (20L pressure-resistant stirred tank), and the materials added to the first reactor also included 4.7kg / h of a mixture of liquid 1-butene and liquid ethane (the molar ratio of 1-butene to ethane was 1:1) and 1g / h of hydrogen. The temperature of the condensate was controlled by adjusting the amount of cooling water added to the first condenser E1 (the tilt angle was 3°) at the top of R2, and then the polymerization temperature of the first reactor was controlled to be 50°C and the pressure to be 2.6MPag.

[0085] After 120 minutes of polymerization in the first reactor, the product in the first reactor continuously flows out from the bottom and is pressurized by the first compression pump P1 and then sent to the second reactor R3 (20L pressure-resistant stirred tank). At the same time, the materials added to the second reactor include 6.3kg / h of a mixture of liquid 1-butene and liquid ethane (the molar ratio of 1-butene to ethane is 1:1.5) and 2g / h of hydrogen. The temperature of the condensate is controlled by adjusting the amount of cooling water added to the second condenser E2 at the top of R3 (the inclination angle is 3°), and the polymerization temperature of the second reactor is controlled to 65°C and the pressure to 2.6MPag.

[0086] After 60 minutes of polymerization in the second reactor, the polymer-containing solution in the second reactor is continuously discharged from the bottom thereof, pressurized to 5 MPag by the second compression pump P2, and then sent to a static mixer. In the static mixer, the polymer-containing solution is fully mixed with an inactivator (ethanol) and an antioxidant (hindered phenolic antioxidant, added in an amount of 0.6% of the weight of the polymer-containing solution), and then enters a devolatilization system. The devolatilization system is divided into two stages of devolatilization, wherein the first stage of devolatilization uses falling strip devolatilization to concentrate the polymer-containing solution, and the conditions of the falling strip devolatilization include a temperature of 120° C., a pressure of 2.0 MPag, and a time of 10 minutes to obtain a polymer melt with a polymer content of 40 wt%; the polymer melt is pressurized by a pump and heated by a heat exchanger, and then enters a secondary devolatilizer, and the secondary devolatilizer uses falling film devolatilization, and the conditions of falling film devolatilization include a temperature of 185° C., a pressure of 1.0 kPaA, and a time of 20 minutes to obtain a polymer melt.

[0087] The polymer melt at the bottom of the secondary devolatilizer is pumped to the granulation system by a gear pump for granulation.

[0088] Example 3

[0089] Poly-1-butene was prepared according to the method of Example 1 of the present invention, except that the molar ratio of 1-butene and ethane added to the first reactor was 1:1.3, and the molar ratio of 1-butene and ethane added to the second reactor was 1:1.3.

[0090] Example 4

[0091] Poly-1-butene was prepared according to the method of Example 1 of the present invention, except that the catalyst was prepared according to the method described in Example 1 of CN93102795.0.

[0092] Example 5

[0093] Poly-1-butene was prepared according to the method of Example 2 of the present invention, except that the catalyst was prepared according to the method described in Example 1 of CN93102795.0.

[0094] Example 6

[0095] Poly-1-butene was prepared according to the method of Example 3 of the present invention, except that the catalyst was prepared according to the method described in Example 1 of CN93102795.0.

[0096] Example 7

[0097] Poly-1-butene was prepared according to the method of Example 1 of the present invention, except that the catalyst was prepared according to the method described in Example 3 of CN200810117894.

[0098] Example 8

[0099] Poly-1-butene was prepared according to the method of Example 2 of the present invention, except that the catalyst was prepared according to the method described in Example 3 of CN200810117894.

[0100] Example 9

[0101] Poly-1-butene was prepared according to the method of Example 3 of the present invention, except that the catalyst was prepared according to the method described in Example 3 of CN200810117894.

[0102] Example 10

[0103] Poly-1-butene was prepared according to the method of Example 1 of the present invention, except that liquid ethane was replaced by liquid propane.

[0104] Embodiment 11

[0105] Poly-1-butene was prepared according to the method of Example 1 of the present invention, except that liquid ethane was replaced by liquid butane.

[0106] Comparative Example 1

[0107] Poly-1-butene was prepared according to the method of Example 1 of the present invention, except that ethane was not added during the polymerization reaction.

[0108] Comparative Example 2

[0109] Poly-1-butene was prepared according to the method of Example 1 of the present invention, except that during the polymerization reaction, no condenser was provided in the first reactor and the second reactor to condense the gas at the top of the reactor, and only the jackets of the first reactor and the second reactor were used for cooling to maintain the temperature of the first reactor and the second reactor at 65° C. At this time, the pressure of the first reactor and the second reactor was 0.76 MPa.

[0110] Test Case

[0111] The polymers in the first reactor and the second reactor (polymers not containing solution) and the pellets after granulation were tested for melt mass flow rate and isotacticity. The results are shown in Table 1.

[0112] The poly-1-butene obtained by granulation was tested for VOC content, and the yield of poly-1-butene was calculated. The results are shown in Table 1.

[0113] The isotacticity of poly-1-butene is determined by the following method: take a certain amount of sample (granules after granulation) and place it in a vacuum oven at 70°C to vacuum dry to extract the residual monomers and moisture in the sample, and vacuum dry to constant weight. Accurately weigh 1-2g of the sample into a filter paper tube, seal the top with a paper clip, place it in an extractor, and extract with boiling ether for 24 hours. Take it out and dry it in a vacuum oven to constant weight. The percentage of unextractable matter in the sample is the isotactic index of poly-1-butene.

[0114] The melt mass flow rate (MFR) is measured by the following method: the test is carried out according to ASTM D1238 standard, using a CEAST 7026 melt mass flow rate tester, the test temperature is 190° C., and the weight is 2.16 kg.

[0115] Table 1

[0116]

[0117] It can be seen from the results in Table 1 that the method of the present invention can not only achieve a high catalyst yield, but also obtain a poly-1-butene product with excellent performance, and the volatile component content (VOC) content in the final product does not exceed 300 ppm.

[0118] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A method for preparing poly-1-butene, characterized in that: The method comprises: in the presence of a catalyst system, polymerizing 1-butene and an optional comonomer in a C2-C4 inert solvent to obtain a polymer-containing solution, collecting and condensing the gas volatilized during the polymerization to obtain a condensate and a non-condensable gas, returning the condensate to the polymerization step, and optionally, returning the non-condensable gas to the polymerization step after being compressed and pressurized; Wherein, the C2-C4 inert solvent is ethane; the 1-butene is liquid 1-butene; The method further includes devolatilizing and pelletizing the polymer-containing solution.

2. The method according to claim 1, wherein: The condensation conditions are such that the polymerization temperature is 40-100° C. and the polymerization pressure is 1-5 MPag; And / or, hydrogen is introduced during the polymerization process, and the molar ratio of 1-butene to hydrogen is 1:0.00001-0.02; and / or, the molar ratio of 1-butene to the C2-C4 inert solvent is 1:0.1-3; And / or, the polymerization time is such that the content of the polymer in the polymer-containing solution is 0.1-50 wt %.

3. The method according to claim 1, wherein: The polymerization time is 0.5-12h.

4. The method according to claim 1, wherein: The polymerization time is 3-8h.

5. The method according to claim 1, wherein: The condensation temperature is below 50°C.

6. The method according to claim 1, wherein: The condensation conditions are such that the polymerization temperature is 50-80°C.

7. The method according to claim 1, wherein: The condensation conditions are such that the polymerization pressure is 2-4 MPag.

8. The method according to claim 1, wherein: The polymerization time is such that the polymer content in the polymer-containing solution is 15-35 wt %.

9. The method according to claim 1, wherein: The preparation method of the catalyst system comprises: performing complexation reaction at 5-30° C. on the catalyst, the co-catalyst and the external electron donor according to a mass ratio of 1:1-100:0.1-20; And / or, the polymerization method includes: (1) subjecting 1-butene and an optional comonomer to a first polymerization in a C2-C4 inert solvent in the presence of a catalyst system; (2) mixing the product of the first polymerization with 1-butene and an optional comonomer to conduct a second polymerization; (3) Optionally, the product of the second polymerization is mixed with 1-butene and an optional comonomer to conduct a third polymerization.

10. The method according to claim 1, wherein: The temperature of the devolatilization treatment is 100-250° C. and the pressure is 0.00001-4 MPa; And / or, the devolatilization treatment includes at least two devolatilization treatments, and the last devolatilization treatment is carried out under vacuum conditions, and the vacuum conditions refer to an absolute pressure of no more than 10 kPaA.

11. The method according to claim 1, wherein: The temperature of the devolatilization treatment is 100-250° C. and the pressure is 0.00001-3 MPa.

12. The method according to claim 1, wherein: The granulation is carried out by underwater granulation.

13. The method according to claim 1, wherein: The method further comprises inactivating the polymer-containing solution before the devolatilization treatment.

14. The method according to claim 13, wherein: The inactivation treatment includes mixing a solution containing a polymer with an antioxidant and an inactivating agent.

15. The method according to claim 14, wherein: The antioxidant is at least one of a hindered phenol antioxidant, a hindered amine antioxidant, a phosphite antioxidant and a sulfide-containing antioxidant.

16. The method according to claim 14, wherein: The antioxidant is a combination of a hindered phenol antioxidant and a phosphite antioxidant.

17. The method according to claim 14, wherein: The inactivating agent is water and / or ethanol.

18. The method according to any one of claims 1 to 17, wherein: The polymerization is carried out in a polymerization reactor, which includes one or more vertical stirring reactors connected in series, and a condenser is arranged above each vertical stirring reactor; The first vertical stirring reactor is used for homogeneous polymerization of 1-butene, and the second and subsequent vertical stirring reactors are used for mixing the reaction product of the previous vertical stirring reactor with 1-butene and optional comonomers for homogeneous polymerization to obtain a polymer-containing solution.

19. The method according to claim 18, wherein: The number of the vertical stirred reactors is 2-3; And / or, the condenser is arranged obliquely above the vertical stirred reactor.

20. The method according to claim 19, wherein: The tilt angle is 0.01°-20°.

21. The method according to claim 19, wherein: The tilt angle is 1°-5°.

22. The method according to any one of claims 1 to 17, wherein: The method is carried out in the following system, which comprises a pre-complexing reactor, a polymerization reactor, a devolatilization device and a granulation device connected in sequence, The pre-complexation reactor is used for pre-complexation reaction of the catalyst, the co-catalyst and the external electron donor; the devolatilization device is used for removing volatiles from the polymer-containing solution; and the granulation device is used for granulating the devolatilized polymer.

23. The method according to claim 22, wherein: The devolatilization device comprises at least two devolatilization devices connected in series.

24. The method according to claim 22, wherein: The granulation device is an underwater granulator.

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