A preparation process of polybutene-1

Abstract

The present invention belongs to the technical field of polymer preparation and discloses a preparation process of polybutene-1, which comprises the following steps: 1) under the action of a Ziegler-Natta catalyst system, 1-butene and optional C2-C 10 The invention relates to a process for preparing a polymer melt comprising: 1) polymerizing an α-olefin monomer in an inert organic solvent or liquid 1-butene at a polymerization temperature of 10-120° C. and a polymerization pressure of 4.1 MPa or higher to obtain a polymer solution; 2) mixing the polymer solution with an antioxidant and a deactivator, and then heating the mixture to obtain a supercritical polymer solution; and 3) devolatilizing the supercritical polymer solution to obtain a polymer melt. The process has low cost, low energy consumption, and excellent polymer properties.

Description

Technical Field

[0001] The present invention belongs to the technical field of polymer preparation, and in particular relates to a preparation process of polybutene-1. Background Art

[0002] Compared to other polyolefin materials, polybutene-1 exhibits outstanding creep resistance, environmental stress cracking resistance, mechanical strength, wear resistance, and impact resistance, making it highly suitable for pipes (hot and cold water pipes, industrial pipes, agricultural pipes, and construction pipes), films, modifiers, waterproofing membranes, and medical and food applications. To expand the application of polybutene-1 and improve the balance between rigidity and toughness, comonomers are often introduced to enhance product performance, resulting in excellent tear resistance, puncture resistance, impact resistance, and tensile strength. Currently, polybutene-1 products are widely used in pipes, medical and food applications, construction, and home furnishings.

[0003] Currently, the preparation methods of polybutene-1 mainly include gas phase method, solution method and bulk method, among which the bulk method includes slurry bulk method and liquid phase bulk method.

[0004] Gas-phase processes generally utilize fluidized-bed reactors. Patents such as CN102040693A, CN1140545C, US4503203, US3168484, US3580898, US5241024, and US3922322 all employ Ziegler-Natta catalyst systems to initiate polymerization of butene-1 monomer directly in a gas fluidized bed, resulting in the synthesis of butene-1 polymers with good particle morphology and a controllable melt mass flow rate (MFR) within a certain range and a high isotactic index. However, gas-phase processes, due to low monomer concentrations and low butene-1 monomer partial pressures, result in low polymerization activity, below 5.0 kgPB / g·Cat, and result in high ash content in the polymer. Furthermore, the catalysts used in these processes are demanding, placing high demands on technology and equipment, making them difficult for general small and medium-sized enterprises to commercialize.

[0005] The solution polymerization process typically involves the polymerization of butene-1 using a Ziegler-Natta catalyst system in an inert solvent that does not participate in the reaction. The solvent used can be n-hexane, isopentane, propane, ethane, isobutane, etc. Patent documents US5037908 and US3944529 utilize a suspension polymerization process using isobutane as the solvent. However, the temperature must be maintained below 45°C, otherwise the polymer will swell or even dissolve in the isobutane. This process also results in low polymerization efficiency, insufficient production capacity, and high ash content in the polymer. The similar boiling points of butene-1 and isobutane complicate monomer separation and recovery. Patent documents US5237013 and CN103304709B use solution polymerization with n-hexane as a diluent to prepare polybutene-1 products. The product precipitates or dissolves in the solvent. This process method is simple to operate, the polymerization reaction heat is easily removed, and the reaction control is stable. However, the polymer will swell or dissolve in high-temperature hexane, making the product morphology uncontrollable. In addition, the monomer concentration in the reaction system is not high, the polymerization efficiency is low, and the equipment production capacity and utilization rate are not high.

[0006] The bulk method using excess butene-1 monomer as solvent can avoid the problem of separation of unreacted monomer and solvent in the post-processing stage, reduce complex separation steps, and reduce costs. It is the most widely used process method. The polybutene-1 product prepared by the bulk precipitation method in patent document CN100488994 has irregular particle morphology and is very easy to stick together, resulting in complicated material transportation and post-processing processes. Patent document CN103288993B uses a multi-stage temperature control method to obtain a polybutene-1 product with a good spherical morphology, with a bulk density of 0.30g / cm 3 , with an isotactic index exceeding 95%. However, since the temperature control in one stage must be below 0-20°C, the residence time is long, which is not conducive to controlled production in industrial equipment. Patent document CN1294161C describes a staged bulk polymerization at 70-75°C, which can produce a product with an isotactic index of up to 99%. However, it does not describe the deactivation or inactivation treatment of the product, nor does it describe the detailed separation process of unreacted monomers from the polymer solution. Patent document CN106893020B uses a Ziegler-Natta catalyst system containing a composite electron donor and adopts a multi-stage sequential polymerization process of first polymerizing propylene and then polymerizing butene-1. It produces butene-1 polymer with good particle morphology. However, to ensure stable and reliable product quality, the required reaction cycle is very long, the monomer polymerization conversion rate is not high, and the product ash content is high, which is not conducive to production.

[0007] The viscosity of the butene-1 / polybutene-1 polymer solution system under the high-temperature bulk process is 1000-100000 cP. After the addition of comonomer, the viscosity of the system will be further increased. After the solution system removes the unreacted monomer, the polymer viscosity can reach up to 20×10 6cP, material transport equipment capacity and heat exchange efficiency requirements are high. Patent document CN103788262B transfers the polymer solution to a sealed container containing hot water, introducing steam from the bottom to deactivate the active centers and simultaneously separate unreacted monomers. While the operation is simple, the polymer easily precipitates and agglomerates, hindering material transport. Furthermore, steam deactivation increases the frequency of recovery and purification tower operations, and trace amounts of water may be entrained in the recovered butene-1, leading to catalyst deactivation.

[0008] In view of the shortcomings of existing equipment technology and process flow, there is still a need for a preparation process suitable for high-viscosity solution systems such as polybutene-1 / butene-1, which can achieve high polymerization efficiency, low production cost, and the ability to adjust the polymer structure and properties over a large range, while solving many problems in the stable operation of high-viscosity system equipment. Summary of the Invention

[0009] In response to the above-mentioned situation, the present invention aims to provide a process for preparing polybutene-1 that effectively reduces the problems caused by the high viscosity of the polybutene-1 / butene-1 solution system, improves the mass and heat transfer efficiency of the device, reduces power consumption, and addresses the drawbacks of difficult post-processing material transportation. This process is simple to operate, low-cost, requires minimal technical and equipment expertise, is easily adaptable to industrial production, and offers high polymerization efficiency. The resulting polymer exhibits excellent performance, and its composition and product properties can be adjusted over a wide range to meet specific application requirements.

[0010] The present invention provides a preparation process of polybutene-1, which comprises the following steps:

[0011] 1) Under the action of Ziegler-Natta catalyst system, 1-butene and optional C2-C 10 The α-olefin monomer is polymerized in an inert organic solvent or liquid 1-butene at a polymerization temperature of 10-120° C. and a polymerization pressure of more than 4.0 MPa to obtain a supercritical polymer solution;

[0012] 2) mixing the polymer solution with an antioxidant and a deactivator, and then heating;

[0013] 3) The heated polymer solution is subjected to a devolatilization unit to remove unreacted monomers or inert solvents to obtain a polymer melt.

[0014] Compared with the prior art, the present invention has the following beneficial effects:

[0015] 1) The present invention can effectively solve the problems existing in the existing high-viscosity polymerization system, enhance the mass transfer and heat transfer efficiency, improve the polymerization production efficiency, and at the same time reduce the load of the device's moving equipment and heat exchange device, greatly reduce the energy consumption of the device, and thus reduce production costs.

[0016] 2) The preparation process of the present invention involves a simple process operation process, simple process technology, and concise equipment selection, which is easy to industrialize for continuous and stable production. The polymer structure and performance can be adjusted within a wide range according to market demand; the prepared polymer product has stable and excellent performance and meets market requirements.

[0017] 3) The polymerization reaction of the present invention is carried out at a pressure of 4.0 MPa or above, which can obtain a higher polymerization yield and adjust the polymer structure and properties in a wider range. At the same time, it is conducive to the smooth operation of the device and reduces the cost and energy consumption of the device.

[0018] Other features and advantages of the present invention will be described in detail in the following detailed description. DETAILED DESCRIPTION

[0019] The following is a detailed description of the specific embodiments of the present invention. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention and are not intended to limit the present invention.

[0020] The present invention provides a preparation process of polybutene-1, which comprises the following steps:

[0021] 1) Under the action of Ziegler-Natta catalyst system, 1-butene and optional C2-C 10 The α-olefin monomer is polymerized in an inert organic solvent or liquid 1-butene at a polymerization temperature of 10-120° C. and a polymerization pressure of more than 4.0 MPa to obtain a supercritical polymer solution;

[0022] 2) mixing the polymer solution with an antioxidant and a deactivator, and then heating;

[0023] 3) The heated polymer solution is subjected to a devolatilization unit to remove unreacted monomers or inert solvents to obtain a polymer melt.

[0024] According to the present invention, C2-C 10 The α-olefin monomer is a monoolefin other than 1-butene having a double bond of 2 to 10 carbon atoms at the end of the molecular chain, and is particularly preferably at least one selected from ethylene, propylene, 1-hexene, 1-octene, and 1-decene. When the polymerized olefin is a mixture of 1-butene and an α-olefin, it is particularly preferred that the amount of 1-butene is 60 to 99.99 mol% and the amount of the α-olefin is 0.01 to 40 mol%.

[0025] In the present invention, the inert organic solvent may be a conventional inert organic solvent in the art, specifically n-hexane, isobutane, n-pentane, propane, isopentane, and the like.

[0026] Preferably, 1-butene and optionally C2-C 10 The α-olefin monomer is polymerized in liquid 1-butene.

[0027] Preferably, the polymerization reaction temperature is 40-100°C and the polymerization reaction pressure is between 4.0-6.0 MPa. Under these operating conditions, higher polymerization yields can be achieved, polymer structure and properties can be adjusted over a wider range, and the device can be operated smoothly, reducing costs and energy consumption.

[0028] According to the present invention, the Ziegler-Natta catalyst system can be any stereoregular Ziegler-Natta catalyst system in the prior art, which generally comprises a solid catalyst component, an organoaluminum compound and an external electron donor.

[0029] Specifically, the solid catalyst component may contain a reaction product of a titanium compound, an internal electron donor, a magnesium compound, and the like.

[0030] The titanium compound may be of the general formula Ti(OR) 4-n X n At least one of the compounds, wherein R is selected from C1-C 14 wherein X is a halogen atom, which may be chlorine, bromine, or iodine; n is an integer selected from 0 to 4; when n is less than 2, R may be the same or different. Specifically, the titanium compound is selected from at least one of tetraalkoxytitanium, titanium tetrahalide, trihaloalkoxytitanium, dihalodialkoxytitanium, and monohalotrialkoxytitanium. More specifically, the tetraalkoxytitanium is selected from at least one of tetramethoxytitanium, tetraethoxytitanium, tetra-n-propoxytitanium, tetraisopropoxytitanium, tetra-n-butoxytitanium, tetraisobutoxytitanium, tetracyclohexyloxytitanium, and tetraphenoxytitanium; the titanium tetrahalide is selected from at least one of titanium tetrachloride, titanium tetrabromide, and titanium tetraiodide; the trihaloalkoxytitanium is selected from at least one of trichloromethoxytitanium, trichloroethoxytitanium, trichloropropoxytitanium, trichloro-n-butoxytitanium, and tribromoethoxytitanium; the dihalodialkoxytitanium is selected from at least one of dimethoxytitanium dichloride, diethoxytitanium dichloride, di-n-propoxytitanium dichloride, diisopropoxytitanium dichloride, and diethoxytitanium dibromide; the monohalotrialkoxytitanium is selected from at least one of trimethoxytitanium monochloride, triethoxytitanium monochloride, tri-n-propoxytitanium monochloride, and triisopropoxytitanium monochloride; the titanium compound is preferably a titanium tetrahalide, and particularly preferably titanium tetrachloride.

[0031] The internal electron donor may be one or more of carboxylate compounds, ether compounds, succinate compounds, 1,3-ol ester compounds and sulfonamide compounds.

[0032] The magnesium compound can be a magnesium halide, specifically selected from magnesium dihalide, a water or alcohol complex of magnesium dihalide, a derivative of magnesium dihalide in which one halogen atom is replaced by a hydrocarbon group or a halohydrocarbonoxy group, or a mixture thereof.

[0033] Specifically, the solid catalyst component can be prepared by referring to the methods in the following patent documents: CN85100997, CN98126383.6, CN98111780.5, CN98126385.2, CN93102795.0, CN00109216.2, CN99125566.6, CN99125567.4, CN02100900.7, CN102453162B, CN103819586B, CN104610474B, CN104 610475B, CN104610476B, CN104610477B, CN104610478B, CN105622800B, CN106543314B, CN106543313B, CN106543312B, CN106543310B, CN106554439B, CN107522800B, CN107522803A, CN107987189B, CN110903420B, CN110950983B, etc.

[0034] The organoaluminum compound can be selected from the group consisting of AlR 1 m X 1 (3-m) Alkyl aluminum compounds with the structure 1 is an alkyl group, aralkyl group, aryl group, etc. having 1 to 20 carbon atoms, X 1 is a halogen, m is an integer from 0 to 3, specifically, the organoaluminum compound can be trimethylaluminum, triethylaluminum, triisobutylaluminum, trihexylaluminum, tri-n-butylaluminum, diethylaluminum monochloride, monoethylaluminum dichloride, dimethylaluminum monochloride, diisobutylaluminum monochloride, diisobutylaluminum dichloride, tri(2-methyl-3-phenyl-butyl)aluminum, tri(2-phenyl-butyl)aluminum, etc. The organoaluminum compound can be selected from aluminum compounds of aluminoxanes, specifically methylaluminoxane, tetra(isobutyl)aluminoxane, tetra(2,4,4-trimethyl-pentyl)aluminoxane, tetra(2,3-dimethylbutyl)aluminoxane, tetra(2,3,3-trimethylbutyl)aluminoxane, etc.

[0035] In the Ziegler-Natta catalyst system, the molar ratio of titanium in the solid catalyst component to aluminum in the organoaluminum compound may be 1:10-1:500, preferably 1:25-1:100.

[0036] The external electron donor can be selected from alkoxysilane compounds, aminosilane compounds, organic amine compounds, ether compounds and the like.

[0037] Specifically, the alkoxysiloxane compound can be selected from at least one of trimethylmethoxysilane, trimethylethoxysilane, methyl tert-butyldimethoxysilane, cyclohexylmethyldimethoxysilane, diisopropyldimethoxysilane, diisobutyldimethoxysilane, dicyclopentyldimethoxysilane, isobutylcyclohexyldimethoxysilane, tetraethoxysilane and n-propylenetriethoxysilane.

[0038] The aminosilane compound can be selected from at least one of diethylaminotriethoxysilane, 3-aminopropyltriethoxysilane, diethylaminomethyltriethoxysilane, dimethylaminomethyltriethoxysilane, diisopropylaminomethyltriethoxysilane, di-n-propylaminomethyltriethoxysilane, 3-(2-aminoethylamino)propyltriethoxysilane, 3-(2-aminoethylamino)propyltrimethoxysilane, piperidinyltriethoxysilane and pyrrolyltriethoxysilane.

[0039] The organic amine compound can be selected from aziridine, azetidine, pyrrolidine, azepane, azioctane, 2,3-dimethylaziridine, 2,2-dimethylaziridine, 2,2,3,3-tetramethylaziridine, 2,2,4,4-tetramethylazetidine, 2,2,4,4-tetraethylazetidine, 2,2,3,3-tetramethylazetidine, 2,2,3,3-tetraethylazetidine, 2,2,4,4-tetramethylpyrrolidine, 2,2,5,5-tetramethylpyrrolidine, 2,2,5,5-tetraethylpyrrolidine, 2, 2,5,5-Tetra-n-propylpyrrolidine, 2,2,5,5-tetraisopropylpyrrolidine, 2,2,5,5-tetraisobutylpyrrolidine, 2,2,6,6-tetramethylpiperidine, 2,2,6,6-tetraethylpiperidine, 2,2,6,6-tetra-n-propylpiperidine, 2,2,6,6-tetraisopropylpiperidine, 2,2,6,6-tetraisobutylpiperidine, 2,2,4,4-tetramethylpiperidine, 2,2,4,4-tetraethylpiperidine, 2,2,5,5-tetramethylpiperidine, 2,2,5,5-tetraethylpiperidine, 2-methyl-2-cyclohexyl-6-methyl-6-ethylpiperidine, 2, 2-dicyclopentyl-6,6-dimethylpiperidine, 2,2,7,7-tetramethylazepane, 2,2,7,7-tetraethylazepane, 2,2,7,7-tetra-n-propylazepane, 2,2,7,7-tetraisopropylazepane, 2,2,7,7-tetraisobutylazepane, 2,2,5,5-tetramethylazepane, 2,2,5,5-tetraethylazepane, 3,3,5,5-tetramethylazepane, 3,3,5,5-tetraethylazepane, 2-methyl-2-cyclohexyl-7-methyl-7-azepane, 2, At least one of 2-dicyclopentyl-7,7-dimethylazacycloheptane, 2,2,8,8-tetramethylazacyclooctane, 2,2,8,8-tetraethylazacyclooctane, 2,2,8,8-tetra-n-propylazacyclooctane, 2,2,8,8-tetraisopropylazacyclooctane, 2,2,8,8-tetra-n-butylazacyclooctane, 2,2,8,8-tetraisobutylazacyclooctane, 2,2,7,7-tetramethylazacyclooctane, 2,2,6,6-tetramethylazacyclooctane, 3,3,5,5-tetramethylazacyclooctane and 3,3,6,6-tetramethylazacyclooctane.

[0040] The ether compound can be selected from 2,2-diisobutyl-1,3-dimethoxypropane, 2,2-phenyl-1,3-dimethoxypropane, 2,2-benzyl-1,3-dimethoxypropane, 2-isopropyl-2-isopentyl-1,3-dimethoxypropane, 2,2-bis(cyclohexylmethyl)-1,3-dimethoxypropane, 2-isopropyl-2-3,7-dimethyloctyl-dimethoxypropane, 2,2-isopropyl-1, At least one of 2-isopropyl-2-cyclohexyl-1,3-dimethoxypropane, 2-isopropyl-2-cyclohexyl-1,3-dimethoxypropane, 2,2-diisobutyl-1,3-diethoxypropane, 2,2-diisobutyl-1,3-dipropoxypropane, 2-isopropyl-2-isopentyl-1,3-diethoxypropane, 2-isopropyl-2-isopentyl-1,3-dipropoxypropane and 2,2-bis(cyclohexylmethyl)-1,3-diethoxypropane.

[0041] The molar ratio of the external electron donor to the aluminum in the organic aluminum compound may be (0.005-0.5):1, preferably (0.01-0.4):1.

[0042] According to the present invention, the components of the Ziegler-Natta catalyst system may optionally undergo a pre-complexation treatment before entering the polymerization reactor. The solid catalyst component, organoaluminum compound, and external electron donor are then used in the polymerization reaction after the pre-complexation treatment. The pre-complexation treatment has the advantage of improving the polymerization activity and stereospecificity of the catalyst system. The pre-complexation treatment temperature is generally 5-30°C, preferably 5-20°C, and the pre-complexation treatment time is 0.1-180 minutes, preferably 5-30 minutes.

[0043] In the present invention, the polymerization reaction is carried out in one or more polymerization reactors connected in series or in parallel. Preferably, the number of polymerization reactors is 2-3. The composition of the polymer can be adjusted by controlling the process parameters (such as reactant composition, temperature, and residence time, etc.) of each polymerization reactor. The polymerization reactor can be a stirred tank reactor or a loop reactor. The average residence time (or average reaction time) of each polymerization reactor connected in series is about 0.5-4 hours, which can be adjusted according to the process conditions so that the content of the polymer in the polymer solution is 0-50wt%, preferably 15-35wt%.

[0044] In addition, hydrogen is introduced during the polymerization process and used as a molecular weight regulator in the polymerization process. That is, according to product requirements, the amount of hydrogen added to each polymerization reactor is controlled to adjust the average molecular weight, molecular weight distribution, melt mass flow rate and other indicators of the product. The polymerization reaction temperature can also be controlled to adjust the average molecular weight of the polymer.

[0045] According to the present invention, the addition of an antioxidant can effectively reduce or avoid the appearance of significant or minor gels in the polymer during subsequent high-temperature flash evaporation, prevent discoloration and degradation of the polymer, ensure stable product quality, avoid damage to the appearance, and prevent the long-term retention of gels in the delivery pump and material handling container, causing coking. The antioxidant can be selected from at least one of a hindered phenol antioxidant, a hindered amine antioxidant, a phosphite antioxidant, and a sulfide-containing antioxidant, preferably a hindered phenol antioxidant and a phosphite antioxidant; the antioxidant is used in an amount of 0.1% to 1.0% by weight of the polymer. The antioxidant can be a solid antioxidant or a liquid antioxidant, preferably a liquid antioxidant. Compared with solid antioxidants, liquid antioxidants are easier to mix with the polymer solution and have a more effective mixing effect.

[0046] In the present invention, the addition of a deactivator can deactivate the active centers in the polymer solution, effectively terminating the polymerization reaction and preventing continued polymerization or implosion during subsequent processing. The deactivator can be a conventional deactivator in the art, such as water, oxygen, carbon dioxide, carbon monoxide, or an alcohol. The alcohol is selected from methanol, ethanol, propanol, ethylene glycol, propylene glycol, or glycerol. The deactivator is used in an amount of 0.1% to 1.0% by weight of the polymer.

[0047] In step 2), the present invention mixes the polymer solution with an antioxidant and a deactivator. During this process, the active components in the polymer solution react with the deactivator to achieve inactivation. Simultaneously, the antioxidant is added at this stage, allowing the polymer to fully contact and mix with the antioxidant, thereby preventing degradation of the polymer's performance during aging in the devolatilization unit. This effectively reduces the amount of additives added and avoids the problem of uneven mixing of the polymer and antioxidant during the extrusion granulation stage, which further deteriorates product performance. This mixing can be performed in a mixer, which can be a stirred autoclave or a static mixer, preferably a static mixer.

[0048] According to the present invention, the polymer solution is heated to a temperature of 80-250°C, preferably 100-220°C. This makes the polymer solution more stable and uniform, prevents phase separation due to 1-butene vaporization during material transportation, and ensures that the polymer solution receives sufficient heat, significantly reducing the operating time and energy consumption of the devolatilization unit. The polymer solution can be heated in a heat exchanger, and a static mixer can be optionally installed in the heat exchange tubes of the heat exchanger to enhance heat transfer.

[0049] It should also be noted that the mixing and heating in step 2) are carried out under the same pressure as the polymerization reaction, which is an operation that those skilled in the art should understand based on the polymer solution being able to reach a supercritical state.

[0050] According to the present invention, the devolatilization treatment achieves effective separation of the polymer from unreacted monomers or inert solvents and other components. Preferably, the devolatilization treatment is carried out in two or more devolatilization devices connected in series, that is, the devolatilization treatment is provided with at least two stages. Generally, the temperature of the first devolatilization treatment is 100-250°C and the pressure is 0-4.0 MPaG, preferably 0-3.0 MPaG. The subsequent devolatilization treatment is operated at near atmospheric pressure or vacuum, and the last stage of devolatilization is carried out under high vacuum to remove as much unreacted monomer as possible from the polymer. A heat exchanger is provided in front of each devolatilization device to provide the heat required for the devolatilization process. At the same time, a gear pump or screw pump suitable for high-viscosity fluids is installed at the bottom of each devolatilization device to deliver the polymer solution or polymer melt to the downstream equipment.

[0051] The polymer melt obtained by the present invention has a mass flow rate of 0.01-400 g / 10 min, a molecular weight distribution of 3.0-10, and a comonomer content of 0-40 mol%.

[0052] In the present invention, the devolatilization treatment further produces 1-butene, which is condensed and purified before being reused. The polymer melt is then pelletized. The pelletization of the polymer melt and the condensation and purification of the 1-butene can be performed using conventional methods in the prior art. For example, a vacuum exhaust pelletizer can be used as the pelletizing equipment to further reduce the volatile content in the polymer. Additives commonly used in the art, such as light stabilizers, antioxidants, colorants, and fillers, can be added to the polymer melt during pelletization.

[0053] In order to deepen the understanding of the preparation process of the present invention, the process flow is further described, but the following embodiments do not limit the scope of the present invention.

[0054] A Ziegler-Natta solid catalyst component, an aluminum alkyl, and an external electron donor are added to a pre-complexing reactor, with the pre-complexing reactor temperature controlled at 10°C and a residence time of 10 minutes. The product of the pre-complexing reactor is directly fed into a first polymerization reactor, where 1-butene, hydrogen, and an optional comonomer, ethylene, are simultaneously added. The reaction is performed at a full reactor temperature of 65°C, a pressure of 4.2 MPa, and a residence time of 2.0 hours. The material from the first polymerization reactor is fed into a second polymerization reactor, where a portion of the 1-butene, hydrogen, and optional comonomer, ethylene, is added to the second polymerization reactor. The second polymerization reactor is operated at a full reactor temperature of 65°C, a pressure of 4.2 MPa, and a residence time of 2 hours.

[0055] The amount of hydrogen added, the amount of comonomer added, the residence time and the polymerization temperature of the two polymerization reactors can be adjusted according to product requirements. By changing the process parameter conditions in the two polymerization reactors, products with different comonomer contents, molecular weight distributions, different melt mass flow rates and other characteristics can be prepared.

[0056] The polymer solution obtained during the polymerization process flows into the mixer and is mixed with the antioxidant and deactivator, so that the active centers in the polymer solution are inactivated and the polymer solution has high-temperature antioxidant ability.

[0057] The 1-butene in the polymer solution is further heated to 150°C in a heat exchanger, ensuring a homogeneous polymer solution and maintaining good heat transfer. The polymer solution then flows into the polymer devolatilization unit, where the polymer and unreacted monomer are effectively separated. The molten polymer exits the final devolatilization stage and is pumped to the pelletizing system.

[0058] The materials, equipment and process parameters not limited in the present invention can be selected according to the existing technology and belong to the conventional technical means in this field.

[0059] The present invention will be further described below with reference to the following examples, but is not limited to these examples.

[0060] In the following examples and comparative examples, the relevant data were obtained according to the following test methods:

[0061] 1. Determination of melt mass flow rate (melt index, MFR): Determined in accordance with standard ISO 1133, experimental conditions 2.16 kg, 190 °C.

[0062] 2. Molecular weight distribution M w / M n Determination of molecular weight: Waters GPC 2000 was used for determination. The sample concentration was 0.1 mg / mL, the test temperature was 150°C, and the test flow rate was 1 mL / min. The molecular weight of polystyrene was used as the internal reference to develop a standard curve. The weight average molecular weight (M) of the sample was calculated based on the elution time. w ), number average molecular weight (M n ) and molecular weight distribution (M w / M n ).

[0063] 3. Determination of isotactic index (II): Weigh about 3 g of polymer, oven-dry to constant weight, then weigh m1. Extract with ether in a Soxhlet extractor for 48 h, and record the mass of the polymer dried to constant weight m2. The weight percentage of insoluble matter after ether extraction (m2 / m1) is the isotactic index of the polymer.

[0064] 4. 13C-NMR measurements of comonomer content were performed in deuterated o-dichlorobenzene solutions (8-12 wt%) of the polymer at 120 °C. A 90° pulse was used with a 15 s delay between the pulse and CPD to remove the 1 H- 13 C coupling, and spectra were acquired at 120°C on a Bruker AV-600 spectrometer operating at 150 MHz in Fourier transform mode.

[0065] Please refer to Carbon-13NMR spectral assignment of five polyolefins determinedfrom the chemical shift calculation and the polymerization mechanism for NMR calculations.

[0066] Example 1

[0067] Solid catalyst component 1 was prepared according to the method of Example 1 in patent document CN107987189B. Solid catalyst component 1, triethylaluminum (TEA), and dicyclopentyldimethoxysilane (DCPMS) were pre-contacted at 6°C for 10 min and then continuously introduced into a polymerization reactor. The flow rate of triethylaluminum was 7.15 g / hr, the flow rate of dicyclopentyldimethoxysilane was 0.48 g / hr, the flow rate of solid catalyst component 1 was 0.6 g / hr, and the molar ratio of TEA to DCPMS was 30:1.

[0068] The polymerization reaction was carried out in two liquid-phase stirred tank reactors connected in series. 1-Butene was continuously introduced into the reactor at a feed rate of 5.9 g / hr and hydrogen was continuously introduced into the reactor at a feed rate of 30 ppm (molar ratio of H2 / 1-butene). The polymerization temperature was 70°C and the polymerization pressure was 4.2 MPa. The residence times in the two reactors were 90 min and 60 min, respectively.

[0069] After the polymerization is completed, the polymer solution is mixed with ethanol and antioxidant 1010 in a static mixer. The amount of ethanol and antioxidant 1010 is 0.3% of the weight of the polymer, respectively. The temperature is then raised to 150°C under the action of a heat exchanger to obtain a supercritical polymer solution.

[0070] The polymer solution in the supercritical state was devolatilized at a primary devolatilization device operating at a pressure of 2.6 MPa and a temperature of 130°C. The temperature was then raised to 190°C and the solution entered a secondary devolatilization device operating at a pressure of 0.5 MPa and a temperature of 170°C to obtain a polymer melt and 1-butene. The 1-butene was condensed and purified and then returned to the polymerization reactor for reuse. The polymer melt was granulated and characterized after air drying. The results are shown in Table 1.

[0071] Example 2

[0072] The difference from Example 1 is that the concentration of hydrogen added to the reactor is 100 ppm, and the rest are the same.

[0073] Example 3

[0074] The difference from Example 1 is that the concentration of hydrogen added to the reactor is 1000 ppm, and the rest are the same.

[0075] Example 4

[0076] The difference from Example 1 is that the reactor feed is 1-butene and ethylene, C2 / (C2+C4) is 1.0 mol%, and the rest are the same.

[0077] Example 5

[0078] The difference from Example 1 is that the reactor feed is 1-butene and propylene, C3 / (C3+C4) is 0.8 mol%, and the rest are the same.

[0079] Example 6

[0080] The difference from Example 1 is that the catalyst was prepared according to the method of Example 2 in CN107522800B, and the rest are the same.

[0081] Example 7

[0082] The difference from Example 1 is that the catalyst was prepared according to the method of Example 1 in CN110950983B, and the rest are the same.

[0083] Comparative Example 1

[0084] The difference from Example 1 is that the polymerization reaction pressure is 2.5 MPa, and the rest are the same.

[0085] Comparative Example 2

[0086] The difference from Example 1 is that no antioxidant is added to the static mixer, and the rest are the same.

[0087] Comparative Example 3

[0088] The difference from Example 6 is that the polymerization pressure is reduced to 2.5 MPa, and the rest are the same.

[0089] Comparative Example 4

[0090] The difference from Example 7 is that the polymerization reaction pressure is 2.5 MPa, and the rest are the same.

[0091] Table 1

[0092]

[0093] As shown in Table 1, the preparation process of the present invention has a high yield, adjustable polymer MFR, and a narrow molecular weight distribution. However, without the addition of an antioxidant to the mixer, the polymer degrades during the subsequent high-temperature devolatilization process, resulting in an increased polymer melt mass flow rate. Furthermore, the reaction pressure is low, resulting in high power consumption and a low overall yield.

[0094] While various embodiments of the present invention have been described above, the above description is intended to be illustrative, not exhaustive, and not limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A process for preparing polybutene-1, characterized in that: The preparation process comprises the following steps: 1) Under the action of Ziegler-Natta catalyst system, 1-butene and optional C2-C 10 The α-olefin monomer is polymerized in an inert organic solvent or liquid 1-butene at a polymerization temperature of 10-120° C. and a polymerization pressure of more than 4.2 MPa to obtain a supercritical polymer solution; 2) Mixing the polymer solution with an antioxidant and a deactivator, and then heating the mixture; the temperature is 150-220° C., and the mixing and heating are carried out under the same pressure as the polymerization reaction; 3) The heated polymer solution is subjected to a devolatilization unit to remove unreacted monomers or inert solvents to obtain a polymer melt.

2. The process for preparing polybutene-1 according to claim 1, wherein 1-butene and optionally C2-C 10 The α-olefin monomer is polymerized in liquid 1-butene.

3. The process for preparing polybutene-1 according to claim 1, wherein: The polymerization reaction temperature is 40-100° C., and the polymerization reaction pressure is between 4.2-6.0 MPa.

4. The process for preparing polybutene-1 according to claim 1, wherein The polymerization reaction is carried out in one or more polymerization reactors connected in series or in parallel, and hydrogen is introduced during the polymerization process.

5. The process for preparing polybutene-1 according to claim 1, wherein: The antioxidant is selected from at least one of hindered phenol antioxidants, hindered amine antioxidants, phosphite antioxidants and sulfide-containing antioxidants.

6. The process for preparing polybutene-1 according to claim 5, wherein: The antioxidants are hindered phenol antioxidants and phosphite antioxidants; the dosage of the antioxidants is 0.1%-1.0% of the weight of the polymer.

7. The process for preparing polybutene-1 according to claim 1, wherein: The deactivator is water, oxygen, carbon dioxide, carbon monoxide or alcohols, and the alcohols are selected from methanol, ethanol, propanol, ethylene glycol, propylene glycol or glycerol; the amount of the deactivator is 0.1%-1.0% of the weight of the polymer.

8. The process for preparing polybutene-1 according to claim 1, wherein: The devolatilization treatment is carried out in two or more devolatilization devices connected in series, and a heat exchanger is provided before each devolatilization device; The temperature of the devolatilization treatment is 100-250°C and the pressure is 0-4.0 MPaG.

9. The process for preparing polybutene-1 according to claim 8, wherein: The pressure is 0-3.0MpaG.

10. The process for preparing polybutene-1 according to claim 1, wherein: The polymer melt has a mass flow rate of 0.01-400 g / 10 min, a molecular weight distribution of 3.0-10, and a comonomer content of 0-40 mol%.

11. The process for preparing polybutene-1 according to claim 1, wherein: The devolatilization treatment also produces 1-butene, which is granulated into polymer melt and reused after condensation and purification.

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