Method for preparing polyolefin elastomer by solution polymerization using loop process

Abstract

The present invention provides a method for preparing a polyolefin elastomer by solution polymerization of a loop process, and belongs to the technical field of olefin polymerization. The method comprises: under anhydrous and oxygen-free conditions, respectively metering and feeding olefin monomers, organic solvents, transition metal catalysts and co-catalysts into a loop reactor through multiple liquid inlets, controlling the temperature and pressure in the loop reactor, polymerizing the olefin monomers, and obtaining a glue solution containing a polyolefin elastomer; detecting the intrinsic viscosity of the glue solution in real time by an online viscosity detection device, determining the viscosity of the glue solution in the loop reactor and the molecular weight of the polymerized product at the same time, and adjusting at least one of the feed ratio, temperature and pressure according to the detection results, so as to achieve stabilization of the polymerization process; the loop reactor is an integrated double loop reactor device, so that the reaction raw materials are in a fully mixed flow state.

Description

Technical Field

[0001] The invention relates to the technical field of olefin polymerization, and in particular to a method for preparing polyolefin elastomer by solution polymerization using a loop process. Background Art

[0002] Polyolefin elastomers are branched polyolefin materials made by copolymerization of ethylene and comonomer α-olefins (propylene, 1-butene, 1-octene, etc.). Since the polyolefin elastomer molecular chain has a high branch content and low density, and the polymer chain is composed of a crystalline resin phase and an amorphous rubber phase, the material has both the high elasticity of rubber and the plasticity and easy processing of thermoplastic resins.

[0003] At present, the preparation of polyolefin elastomers is divided into two categories according to the different types of reaction monomers, namely, homopolymerization of ethylene and copolymerization of ethylene and α-olefins. Homopolymerization is based on a late transition metal catalytic system, catalyzing the chain walking homopolymerization of ethylene and other monomers to prepare polyolefin elastomer materials. Copolymerization reaction is the preparation of polyolefin elastomers by copolymerizing ethylene and α-olefins catalyzed by bridged, non-bridged metallocene, and constrained geometry (CGC) metallocene catalysts. The main polyolefin elastomers may include ethylene-propylene copolymers (abbreviated as ethylene-propylene PBE), ethylene-butene copolymers (abbreviated as ethylene-butene POE), and ethylene-octene copolymers (abbreviated as ethylene-octene POE). At the same content, polyolefin elastomers have the characteristics of lower density and higher volume resistivity, and show higher volume resistance and anti-potential induced degradation (PID) performance in photovoltaic film applications.

[0004] At present, the method for preparing polyolefins mainly utilizes a kettle reactor to prepare polyolefin elastomers by copolymerizing ethylene and α-olefins. The production equipment investment cost is high, the floor space is large, the process stability is poor, and the production efficiency is low. Summary of the invention

[0005] In view of this, in order to at least partially solve at least one of the above-mentioned technical problems, the present invention provides a method for preparing a polyolefin elastomer by solution polymerization through a loop process.

[0006] According to an embodiment of one aspect of the present invention, a method for preparing a polyolefin elastomer by solution polymerization of a loop tube process is provided, comprising: under anhydrous and oxygen-free conditions, respectively metering olefin monomers, organic solvents, transition metal catalysts and co-catalysts into a loop tube reactor through multiple liquid inlets, controlling the temperature and pressure in the loop tube reactor to polymerize the olefin monomers to obtain a glue solution containing a polyolefin elastomer; wherein, the characteristic viscosity of the glue solution is detected in real time by an online viscosity detection device, and the viscosity of the glue solution in the loop tube reactor and the molecular weight of the polymerization product are determined at the same time, and at least one of the feed ratio, temperature and pressure is adjusted according to the detection result to achieve stabilization of the polymerization process; the loop tube reactor is an integrated double loop tube reaction device so that the reaction raw materials are in a fully mixed flow state.

[0007] According to an embodiment of the present invention, an online viscosity detection device is arranged at the liquid outlet of the annular tube reactor, including: an inlet washing tube; a liquid storage ball, which is connected to the inlet washing tube and is suitable for receiving the glue liquid from the inlet washing tube; a buffer tube, which is partially sleeved inside the liquid storage ball and is suitable for receiving the glue liquid from the liquid storage ball; and a measuring tube, which is connected to the bottom of the buffer tube and is arranged parallel to the inlet washing tube and is suitable for measuring the viscosity of the glue liquid from the buffer tube.

[0008] According to an embodiment of the present invention, the measuring tube includes: a capillary tube, which is connected to the buffer tube and is set above the buffer tube, and is suitable for regulating the flow rate of the glue; a measuring ball, which is connected to the capillary tube and is set above the capillary, and is suitable for determining the viscosity and molecular weight of the glue by the time the glue flows through the measuring ball; the inner diameter of the capillary tube is 1~3mm.

[0009] According to an embodiment of the present invention, the inner diameter of the loop reactor is 20-80 cm, the height of the loop reactor is 7.5-75 m, and the total length of the flow path of the olefin monomer in the loop reactor is 30-300 m.

[0010] According to an embodiment of the present invention, the viscosity of the glue is 1000-5000 cps.

[0011] According to an embodiment of the present invention, when there is only one olefin monomer, the mass ratio of the olefin monomer to the organic solvent is (5-50):(50-95).

[0012] According to an embodiment of the present invention, the co-catalyst includes at least one of alkyl aluminum, alkoxy aluminum, and alkyl aluminum halide; the olefin monomer includes at least one of ethylene, propylene, butene, and hexene; the organic solvent includes at least one of pentane, hexane, heptane, cyclohexane, and toluene; the transition metal catalyst includes a homogeneous transition metal catalyst; the molar ratio of aluminum in the co-catalyst to the transition metal in the transition metal catalyst is (100~2000):1.

[0013] According to an embodiment of the present invention, the number average molecular weight of the polyolefin elastomer is (5-30)×10 4 g / mol; the viscosity average molecular weight of polyolefin elastomer is (3~10)×10 4 g / mol.

[0014] According to an embodiment of the present invention, the polymerization temperature is 20-150° C., the pressure is 0.1-15 MPa, and the time is 1-4 h.

[0015] According to an embodiment of the present invention, the method further comprises: sequentially performing dry devolatilization and granulation on the rubber solution to obtain a polyolefin elastomer; wherein the temperature of the dry devolatilization is 150-300°C.

[0016] According to the embodiments of the present invention, the loop reactor used in the present invention has a simple structure, convenient design, large heat exchange area, and high heat transfer coefficient, so that the glue liquid is in a state of full mixed flow more evenly. By setting an online viscosity detection device, it is helpful to detect the characteristic viscosity in real time. By detecting the characteristic viscosity, the viscosity of the glue liquid in the loop reactor and the molecular weight of the polymer product can be determined at the same time. While the viscosity change of the reaction glue liquid in the reaction system is immediately understood, the molecular weight of the polymer product can be determined, avoiding the tediousness of separate measurements and the measurement errors caused. In addition, the feed amount of the reaction raw materials can be adjusted in time through the viscosity change, which helps to avoid the phenomena of implosion, wall adhesion, and reaction out of control in the loop reactor, and improve the stability of the loop reactor and the continuity of the reaction. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The above and other objects, features and advantages of the present invention will become more apparent through the following description of the embodiments of the present invention with reference to the accompanying drawings, in which:

[0018] Figure 1 A flow chart showing a method for preparing polyolefin elastomer by solution polymerization using a loop process according to an embodiment of the present invention is shown;

[0019] Figure 2 A schematic structural diagram of an online viscosity detection device according to an embodiment of the present invention is shown;

[0020] Figure 3 A schematic structural diagram of a loop reactor according to an embodiment of the present invention is shown;

[0021] Figure 4 The hydrogen nuclear magnetic resonance spectrum of the polyolefin elastomer 3 prepared in Example 3 of the present invention is shown.

[0022] [Description of Reference Numerals]

[0023] 1-Online viscosity detection device;

[0024] 11-injection washing tube;

[0025] 12-liquid storage ball;

[0026] 13- buffer tube;

[0027] 14- measuring tube;

[0028] 15-capillary;

[0029] 16- Measuring ball;

[0030] 2-Axial flow pump;

[0031] 3- Gear pump;

[0032] A-liquid outlet;

[0033] B-Liquid inlet. DETAILED DESCRIPTION

[0034] Below, embodiments of the present invention will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the present invention. In the following detailed description, for ease of explanation, many specific details are set forth to provide a comprehensive understanding of embodiments of the present invention. However, it is apparent that one or more embodiments may also be implemented without these specific details. In addition, in the following description, descriptions of known structures and technologies are omitted to avoid unnecessary confusion of concepts of the present invention.

[0035] The terms used herein are only for describing specific embodiments and are not intended to limit the present invention. The term "comprising" used herein indicates the existence of features, steps, operations, but does not exclude the existence or addition of one or more other features.

[0036] In the case of using expressions such as "at least one of A, B, and C, etc.", it should generally be interpreted in accordance with the meaning of the expression generally understood by those skilled in the art (for example, "a system having at least one of A, B, and C" should include but is not limited to a system having A alone, B alone, C alone, A and B, A and C, B and C, and / or A, B, C, etc.). In the case of using expressions such as "at least one of A, B, or C, etc.", it should generally be interpreted in accordance with the meaning of the expression generally understood by those skilled in the art (for example, "a system having at least one of A, B, or C" should include but is not limited to a system having A alone, B alone, C alone, A and B, A and C, B and C, and / or A, B, C, etc.).

[0037] In recent years, industries such as photovoltaics, replacing steel with plastics, and plastic reinforcement and toughening have developed rapidly, and the demand for polyolefin elastomers has increased significantly.

[0038] One approach of the related technology is to convert ethylene, Under the catalytic action of the catalyst, the reaction is carried out in two polymerization reactors connected in series or in parallel to obtain a polyolefin glue solution. However, when using multiple reactors for polymerization, it is necessary to control the conditions of each reactor separately, which is a complex process. Improper operation can easily affect the stable operation of the device.

[0039] Another method of the related art is to combine ethylene, Under the catalytic action of metallocene catalysts, polyolefin elastomers are prepared by continuous copolymerization in a kettle reactor. The investment cost of production equipment is high, the floor space is large, the process stability is poor, and the production efficiency is low.

[0040] In the process of realizing the concept of the present invention, it is found that by using a loop reactor to polymerize one or more olefin monomers, the mass transfer time can be increased, the heat exchange effect can be improved, and the olefin monomers can be evenly dispersed and the activity of the reaction catalyst can be improved. However, since the viscosity of polyolefin elastomers is difficult to control, it is easy to produce uncontrolled rapid polymerization (implosion) in the loop reactor, resulting in polyolefin elastomer wall adhesion, reaction out of control, etc., so that when using a loop reactor to polymerize polyolefin elastomers, the stability and continuity are poor.

[0041] Furthermore, in order to solve the above problems, an online viscosity detection device is provided to detect the intrinsic viscosity in real time. By detecting the intrinsic viscosity, the viscosity of the glue liquid in the loop reactor and the molecular weight of the polymer product can be determined simultaneously. The determination of the viscosity of the glue liquid can adjust the feed amount and feed ratio of the reaction raw materials in real time, thereby controlling the viscosity of the glue liquid within an appropriate range. Determining the molecular weight of the polymer product avoids the cumbersome steps of separate measurements and the errors that may be caused by separate measurements.

[0042] Specifically, according to an embodiment of one aspect of the present invention, a method for preparing a polyolefin elastomer by solution polymerization using a loop process is provided. Figure 1 The flow chart of the method for preparing polyolefin elastomer by solution polymerization using a loop process according to an embodiment of the present invention is shown as follows: Figure 1 As shown, operations S101 to S104 are included.

[0043] In operation S101, under anhydrous and oxygen-free condition, olefin monomer, organic solvent, transition metal catalyst and co-catalyst are metered and fed into a loop reactor through multiple liquid inlets.

[0044] In operation S102, the temperature and pressure in the loop reactor are controlled to polymerize the olefin monomers to obtain a rubber solution containing a polyolefin elastomer.

[0045] In operation S103, the intrinsic viscosity of the glue solution is detected in real time by an online viscosity detection device, and the viscosity of the glue solution in the loop reactor and the molecular weight of the polymerization product are determined simultaneously.

[0046] In operation S104, at least one of the feed ratio, temperature and pressure is adjusted according to the detection result to achieve stabilization of the polymerization process.

[0047] According to an embodiment of the present invention, a plurality of reaction raw materials are metered and fed into the loop reactor through a plurality of liquid inlets, which helps to ensure uniform mixing of the reaction raw materials and reduce the problem of overreaction or insufficient reaction that may be caused by excessive local concentration. The loop reactor is applied to the preparation process of polyolefin elastomer, and its structure is simple and convenient to design. The loop reactor can, for example, perform heat exchange by using a cooling water jacket, and the heat exchange area per unit volume is large and the heat transfer coefficient is high. The characteristic viscosity of the glue solution is detected in real time by an online viscosity detection device, and the viscosity of the glue solution in the loop reactor and the molecular weight of the polymerization product are determined at the same time, and at least one of the feed ratio, temperature and pressure is adjusted according to the detection results to achieve stabilization of the polymerization process and reduce the states of implosion, wall adhesion, and out-of-control reaction process in the loop reactor.

[0048] It should be noted that the loop reactor is an integrated double loop reactor, such as Figure 3 As shown, by setting up an integrated double-loop tube reaction device, a surrounding flow path is formed, which helps to extend the flow path of reaction raw materials such as olefin monomers, organic solvents, transition metal catalysts and co-catalysts, and promotes the reaction raw materials to be in a fully mixed state, further improving the sufficiency of the polymerization reaction while taking into account the fluidity of the polymerization reaction.

[0049] Specifically, by detecting the intrinsic viscosity in real time, it is possible to assist in adjusting the metered feed ratio of various reaction raw materials, thereby adjusting the viscosity of the glue solution within an appropriate range, which is conducive to the continuous progress of the solution polymerization reaction.

[0050] Furthermore, by detecting the intrinsic viscosity, the viscosity of the rubber liquid in the annular tube reactor and the molecular weight of the polymerization product can be determined simultaneously. The molecular weight of the polymerization product can be determined while the viscosity change of the reaction rubber liquid in the reaction system is instantly understood, thus avoiding the tediousness of separate measurements and the resulting measurement errors.

[0051] Specifically, the online viscosity detection device can be arranged at the liquid outlet of the loop reactor as required. Figure 2 The schematic diagram of the structure of the online viscosity detection device 1 according to the embodiment of the present invention is shown as follows: Figure 2As shown, it includes: a sample injection washing tube 11, a liquid storage ball 12, a buffer tube 13, and a measuring tube 14. The online viscosity detection device 1 can be washed with a solvent as needed before use to discharge dust and impurities attached to the inside of the online viscosity detection device 1. The sample injection washing tube 11 is suitable for receiving the glue liquid from the liquid outlet A of the annular tube reactor and performing preliminary washing on the glue liquid so that the outflowing glue liquid is relatively pure and suitable for measurement. The liquid storage ball 12 is connected to the sample injection washing tube 11, and is suitable for receiving the glue liquid from the sample injection washing tube 11 and stabilizing the flow rate of the glue liquid. The buffer tube 13 is partially sleeved inside the liquid storage ball 12, and is suitable for receiving the glue liquid from the liquid storage ball 12. By sleeved, the pressure change generated when the glue liquid flows is reduced, and it is ensured that the glue liquid can flow into the measuring tube 14 more smoothly. The measuring tube 14 is connected to the bottom of the buffer tube 13 and is arranged parallel to the sample injection washing tube 11 and spaced apart, and is suitable for measuring the viscosity of the glue liquid from the buffer tube 13.

[0052] According to an embodiment of the present invention, the online viscosity detection device 1 also includes: a capillary 15 and a measuring ball 16. The capillary 15 is connected to the buffer tube 13 and is set above the buffer tube 13, and is suitable for regulating the flow rate of the glue. The inner diameter of the capillary 15 is 1~3mm, for example, it can be 1mm, 2mm or 3mm. By adjusting the inner diameter parameter of the capillary 15, the flow rate of the glue can be regulated to ensure that the glue flows into the measuring ball 16 at a suitable flow rate. The measuring ball 16 is connected to the capillary 13 and is set above the capillary 13, and is suitable for determining the viscosity of the glue and the molecular weight of the polymerization product by the time the glue flows through the measuring ball 16. Specifically, for example, the bottom of the measuring ball 16 can be marked as a lower mark, and the top of the measuring ball 16 can be marked as an upper mark, and the time for the glue to pass from the lower mark to the upper mark can be used to determine the characteristic viscosity η of the glue. sp , and then determine the specific concentration viscosity [η].

[0053] Specifically, the formula for the specific concentration viscosity [η] is as shown in the following formula (1):

[0054] (1) Where, relative viscosity η r ≈t / t0 (t, t0 are the outflow time of a certain volume of glue and solvent measured by the same viscometer at the same temperature), c is the concentration of the glue.

[0055] Furthermore, the viscosity average molecular weight M of the polymer product v Viscosity vs. Concentration The formula between is shown in the following formula (2):

[0056] (2) Wherein, K and α are constants. In the glue solution of the present invention, the range of K is 4-6, and the range of α is 1-2.

[0057] Furthermore, the actual viscosity of the glue Viscosity vs. Concentration The relationship between them is shown in the following formula (3): (3).

[0058] The actual viscosity and the specific concentration viscosity satisfy The inventor obtained this result after a large number of experiments, and by adjusting the polymerization reaction temperature, pressure, feed ratio and other process indicators closely related to the polymerization process parameters, the polymerization process is ensured to be controllable, and the product quality is stable and controllable to ensure quality.

[0059] Accordingly, the present invention determines the intrinsic viscosity of the glue by determining the time for the glue to pass through the lower mark of the measuring ball 16 to the upper mark. , thereby determining the specific concentration viscosity and molecular weight of the glue solution. The present invention simultaneously determines the glue solution viscosity and the molecular weight of the polyolefin elastomer through the characteristic viscosity, and associates the two together, avoiding the trouble and error of separate measurements, especially the conventional viscosity measurement method has a large error, and it is difficult to accurately judge the glue solution viscosity and the molecular weight of the polyolefin elastomer through a one-step measurement method.

[0060] According to an embodiment of the present invention, the inner diameter of the loop reactor is 20-80 cm, for example, it can be 20 cm, 30 cm, 40 cm, 50 cm, 60 cm, 70 cm or 80 cm. The height of the loop reactor is 7.5-75 m, for example, it can be 7.5 m, 15 m, 20 m, 25 m, 30 m, 35 m, 40 m, 45 m, 50 m, 55 m, 60 m, 65 m, 70 m or 75 m. The total length of the flow path of the olefin monomer in the loop reactor is 30-300 m, for example, it can be 30 m, 60 m, 90 m, 100 m, 150 m, 200 m, 250 m or 300 m. By adjusting the parameters of the loop reactor within the above range, it is helpful to enable the olefin monomer to react more fully, so that the heat exchange effect is better and the reaction efficiency is higher. Specifically, the above inner diameter makes it easier for heat to be transferred from the reaction medium to the wall of the annular tube reactor, and is taken away by an external cooling medium (such as cooling water), thereby avoiding local overheating, so that a larger heat exchange area is provided per unit volume and a higher heat transfer coefficient is obtained.

[0061] Figure 3 The schematic diagram of the structure of the loop reactor of the embodiment of the present invention is shown. Figure 3 As shown, the loop reactor used in the present invention belongs to a double loop reactor, which has a simple structure and is convenient to design. By arranging an axial flow pump 2 near the liquid inlet B of the reaction raw material at the first loop of the single loop reactor, the olefin monomer, catalyst, solvent, recycled glue, etc. entering the loop reactor are distributed more evenly, which is beneficial to the full reaction of the olefin monomer. It should be noted that Figure 3 The liquid inlet B is only an example. In actual application, different liquid inlets B can be used to realize the feeding process according to different reaction raw materials. The same is true for the liquid outlet A. Multiple liquid outlets A can be set on the loop reactor as needed, which further facilitates the real-time detection of the intrinsic viscosity of the glue solution.

[0062] A gear pump 3 is provided at the second annular tube of the annular tube reactor, and the gear pump 3 is in a series connection with the axial flow pump 2. The glue liquid and unreacted olefin monomers delivered by the axial flow pump 2 enter the gear pump 3, and a series of working chambers are formed in the pump body through the rotation of the gear pump 3, forming a local vacuum, sucking the glue liquid, and the gear continues to rotate. The glue liquid in the suction chamber is brought into the extrusion chamber, and the glue liquid is compressed and discharged through the exhaust pipeline. The gear pump 3 can realize the continuous suction and discharge of the glue liquid, complete the glue liquid delivery task, and after passing through the gear pump 3, the glue liquid is evenly distributed again to form a full mixed flow state. The present invention can make the catalyst, olefin monomer, solvent, etc. distributed evenly by using a dual pump series circulation method in the annular tube reactor, and at the same time make the glue liquid distribution more even, which is helpful to be in a full mixed flow state, further reduce the occurrence of implosion, wall adhesion, reaction out of control, etc. in the annular tube reactor, and further improve the stability of the annular tube reactor.

[0063] It should be noted that Figure 3 The dotted line on the middle ring tube reactor indicates the obscured part. Figure 3 Two loops are shown, but more loops can be connected in series.

[0064] Furthermore, the polyolefin elastomer prepared by the ring tube process solution polymerization of the present invention has a low molecular weight distribution (PDI=1-5), and the obtained polyolefin elastomer can be applied to the photovoltaic field, and can use relevant solution polymerization production processes including metallocene catalysts, transition metal catalysts, rubber elastomer catalytic systems, etc. to produce polymers. It has the advantages of wide application range, stable process, wide adjustability, etc., and has broad application value.

[0065] According to an embodiment of the present invention, the viscosity of the glue solution is 1000-5000cps, for example, 1000cps, 2000cps, 3000cps, 4000cps or 5000cps. When the viscosity is adjusted within the above range by an online viscosity detection device, it is more conducive to the glue solution being in a mixed flow state, and the metered feed amount of each reaction raw material can be adjusted according to the viscosity of the glue solution as needed, which helps to maintain the continuity and stability of the solution in continuously preparing the polyolefin elastomer.

[0066] According to an embodiment of the present invention, when the olefin monomer is one, for example, ethylene monomer, the mass ratio of the olefin monomer to the organic solvent is (5-50): (50-95). In the process of conducting experiments related to the present invention, it is found that by adjusting the feed ratio of the olefin monomer to the organic solvent within the above range, it is helpful to form a fully mixed flow state in the solution polymerization process, and it is more helpful to reduce the wall adhesion, implosion, etc. of the polyolefin elastomer.

[0067] According to an embodiment of the present invention, the cocatalyst includes at least one of alkyl aluminum, alkoxy aluminum, and alkyl aluminum halide. The alkyl aluminum may be, for example, at least one of trimethyl aluminum, triethyl aluminum, and triisobutyl aluminum; the alkoxy aluminum may be, for example, at least one of methyl aluminumoxane, modified methyl aluminumoxane, and ethyl aluminumoxane; the alkyl aluminum halide may be, for example, at least one of diethyl aluminum monochloride, dichloroethyl aluminum dichloride, and sesquiethyl aluminum. The olefin monomer includes at least one of ethylene, propylene, butene, and hexene; the organic solvent includes at least one of pentane, hexane, heptane, cyclohexane, and toluene; the transition metal catalyst includes a homogeneous transition metal catalyst, for example, a pre-transition metal catalyst and a post-transition metal catalyst. The pre-transition metal may be, for example, Ti, Zr, or Hf, and may be, for example, a metallocene catalyst, preferably a CGC metallocene catalyst. The pre-transition metal catalyst is suitable for the copolymerization of ethylene and other α-olefins. The post-transition metal catalyst may be, for example, Fe, Co, Ni, or Pd, and the post-transition metal catalyst is suitable for the homopolymerization of ethylene monomers. The molar ratio of aluminum in the co-catalyst to the transition metal in the transition metal catalyst is (100-2000):1, for example, 100:1, 500:1, 1000:1, 1500:1 or 2000:1.

[0068] For example, the metallocene catalyst used includes the structural formula shown in the following formula I or formula II:

[0069] Formula I Formula II.

[0070] In Formula I, Z includes Si or C; X includes chlorine or C1-C5 alkyl; M includes Ti, Zr or Hf; R 1 ~R 4 Including C1~C5 alkyl or C6~C 20 In Formula II, R includes tert-butyl, isopropyl or phenyl.

[0071] For example, the late transition metal catalyst used includes the structural formula shown in the following formula III or formula IV:

[0072] Formula III Formula IV.

[0073] In formula III, R1 includes hydrogen or methyl; R2 includes isopropyl or tert-butyl; X1 and Y1 are each chlorine, bromine or iodine. In formula IV, R3 includes hydrogen, methyl or methoxy; X2 and Y2 are each chlorine, bromine or iodine.

[0074] According to an embodiment of the present invention, the number average molecular weight M of the polyolefin elastomer is n =(5~30)×10 4 g / mol; viscosity average molecular weight M of polyolefin elastomer v =(3~10)×10 4 g / mol, for example, 3×10 4 g / mol, 5×10 4 g / mol, 7×10 4 g / mol, 9×10 4 g / mol or 1×10 5 During the relevant experiments of the present invention, it was found that when the viscosity average molecular weight of the obtained polyolefin elastomer is within the above range, it can ensure good fluidity in the loop reactor and is not prone to wall adhesion and implosion.

[0075] According to an embodiment of the present invention, the polymerization temperature is 20-150°C, for example, 20°C, 40°C, 60°C, 80°C, 100°C, 120°C, 140°C or 150°C. It should be noted that when the loop reactor is heated, the temperature of the polymerization reaction can be regulated by an external heating medium (such as heat transfer oil) as needed. The pressure is 0.1-15MPa, for example, 0.1MPa, 0.5MPa, 1MPa, 3MPa, 5MPa, 7MPa, 9MPa, 11MPa, 13MPa or 15MPa, and the time is 1-4h, for example, 1h, 2h, 3h or 4h. The intrinsic viscosity detected in real time by the online viscosity detection device 1, when the adjusted temperature, pressure and reaction time are within the above range, the continuity and stability of the prepared glue containing polyolefin elastomer are better, so that the quality of the prepared polyolefin elastomer is more stable and reliable.

[0076] According to an embodiment of the present invention, the concentration percentage of the obtained glue solution is 5-50%, for example, it can be 5%, 8%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45% or 50%, preferably 8-15%.

[0077] According to an embodiment of the present invention, the method also includes: removing transition metal catalysts, co-catalysts, impurity particles, etc. in the glue solution through a flash tank, purifying the glue solution to improve the light transmittance of the glue solution, and reducing the ash content of the glue solution, so that the ash content of the glue solution after deashing is less than 300ppm.

[0078] According to an embodiment of the present invention, the method further comprises: sequentially performing dry devolatilization and granulation on the rubber solution to obtain a polyolefin elastomer; the temperature of the dry devolatilization is 150-300° C. Dry devolatilization helps to remove the organic solvent used in the solution polymerization process, reduce production costs, and reduce environmental pollution.

[0079] According to an embodiment of the present invention, by using a loop tube reactor and coupling it with an online viscosity detection device 1, the production capacity of the polymerization device can be greatly improved, the stability of the solution polymerization process can be improved, and the energy consumption can be reduced. The loop tube process has strong reliability, the loop tube reactor occupies a small area, and the equipment cost is low, and a solution polymerization process of different types of homogeneous catalysts can be realized.

[0080] In one of the embodiments, one or more olefin monomers, organic solvents, transition metal catalysts and co-catalysts are accurately metered under anhydrous and oxygen-free conditions and then introduced into a loop reactor. The stability of the process parameters is controlled by controlling the feed ratio, polymerization reaction temperature, and a circulating cooling device. A high-performance polyolefin elastomer is prepared through monomer recovery, heating and concentration, refining and impurity removal, dry devolatilization, granulation and packaging.

[0081] It should be noted that the solvent and unreacted monomers in the glue are small molecules and will not affect the determination of the molecular weight.

[0082] Specifically, the preparation process can be as follows:

[0083] Olefin monomer, organic solvent, transition metal catalyst and co-catalyst are respectively introduced into the annular tube reactor from the liquid inlet, and a full mixed flow reaction is carried out in the annular tube reactor by means of the axial flow pump 2 in the annular tube reactor. The important key indicators such as the viscosity, molecular weight, inlet and outlet flow of the rubber in the reactor are detected in real time by the online viscosity detection device 1, and the feed ratio of olefin monomer, organic solvent, transition metal catalyst and co-catalyst is adjusted to stabilize the polymerization process and ensure that the physical properties of the polyolefin elastomer produced by the polymerization are stable and reliable.

[0084] Flash recovery process: Flash recovery polymerization and olefin monomer recovery of reaction materials. The glue liquid from the polymerization reaction enters the flash tank for flash evaporation, recovers the solvent through the first and second condensation, and then recovers the unreacted olefin monomer through compression condensation. After purification in the refining tower, it enters the ethylene recovery tank for standby.

[0085] Liquid glue ash removal process: After flash evaporation to remove more olefin monomers, the liquid glue is transferred to the refining tower through a pump. The refining device of the refining tower automatically switches the refining device according to the pressure before and after the tower. At the same time, the refined materials can be reused to further reduce production costs. The main function of the refining tower is to remove catalysts, co-catalysts, impurity particles, etc. in the liquid glue, purify the liquid glue, improve light transmittance, and reduce the ash content of the liquid glue. Its ash content is less than 300ppm.

[0086] Devolatilization granulation process: After purification and deashing, the high-concentration rubber liquid is automatically transferred to the dry deashing device through a metering pump. After multi-stage deashing treatment, it is pelletized by a screw extruder and automatically packaged to prepare a polyolefin elastomer.

[0087] In the flash recovery process, the flash tank can be a flash tank with stirring, which belongs to the secondary flash. The primary flash is mainly used for olefin monomer recovery. The primary flash reaction temperature is controlled at 20~150℃ and the reaction pressure is normal pressure; the secondary flash is mainly used for solvent recovery, and the reaction temperature is controlled at 70~150℃. The stirring structure of the flash tank can be one or a combination of flat blades, oblique (folded) blades, curved blades, spiral blades, anchor type, frame type, propeller type, and ribbon type.

[0088] In the glue liquid ash removal process, the refining device of the refining tower can automatically switch to the spare refining tower according to the pressure before and after the tower of 0~7MPa and the glue liquid temperature of 50~150℃. After the glue liquid pressure exceeds 7MPa, the refining tower can be cleaned at the same time, and the cleaned glue liquid can be recycled after treatment to reduce production costs.

[0089] In the devolatilization granulation process, one or a combination of wet deashing, dry deashing processes, etc. can be used, preferably dry deashing. After vacuum deashing, the volatile organic compound (VOC) content can be reduced to below 10~200ppm. The temperature of the first deashing is controlled at 55-110℃, and the speed is 20~100r / min; the temperature of the first deashing is controlled at 110~150℃, and the speed is 20~80r / min; the temperature of the third deashing is controlled at 150~250℃, and the speed is 20~60r / min.

[0090] The present invention discloses a method for preparing a polyolefin elastomer by solution polymerization through a loop process. Based on a transition metal catalyst, the polyolefin elastomer can be prepared by solution polymerization using a homogeneous catalyst such as a metallocene catalyst and a late transition metal catalyst. The preparation process of the method mainly includes a solvent monomer purification device, a loop reactor, a flash recovery device, a refined deashing device, and a devolatilization granulation device. By combining several devices, the investment cost can be significantly reduced, land can be saved, the process control is stable, the unit consumption of the product is reduced, and the product quality is improved.

[0091] The present invention is further described below by embodiments and related test experiments and results thereof. In the detailed description below, for ease of explanation, many specific details are set forth to provide a comprehensive understanding of the embodiments of the present invention. However, it is obvious that one or more embodiments may also be implemented without these specific details. And, in the absence of conflict, the details in the following embodiments may be combined into other feasible embodiments at will.

[0092] It should be noted that the following specific examples are only for illustration, and the protection scope of the present invention is not limited thereto. The chemicals and raw materials used in the following examples are all commercially available or homemade by recognized processing methods.

[0093] The specimens were prepared by compression molding in accordance with the provisions of GB / T 9352-2008. The specimen state adjustment for density, hardness, tensile fracture stress, tensile fracture strain, volume resistivity, and transmittance testing was carried out in accordance with the provisions of GB / T 2918-2018, and the state adjustment conditions were 23°C ± 2°C and relative humidity (50 ± 10)%.

[0094] The test is carried out according to the method specified in SH / T1541.1-2015 for particle appearance inspection. The melt index test is carried out according to the provisions of Method A in GB / T3682.1-2018. The density test is carried out according to the provisions of the immersion method in GB / T1033.1-2008. The mechanical properties test is carried out according to the method specified in GB / T1040.3-2018. The tear strength test is carried out according to the provisions of Method B in GB / T529. The Shore hardness test is carried out according to the provisions of the Shore A durometer method in GB / T2411-2008. The volume resistivity test is carried out according to the method specified in GB / T31838.2-2015. The transmittance test is carried out according to the provisions of the spectrophotometry method in GB / T2410-2008. The melting point test is tested according to the method specified in GB / T19466.3-2004. The glass transition temperature test is carried out according to the method specified in GB / T19466.2-2004.

[0095] Embodiment 1:

[0096] Reaction raw materials: toluene is used as an organic solvent, and a metallocene catalyst is used as a transition metal catalyst, which is catalyst A shown in the following formula A. The product is a polyolefin elastomer 1 obtained by copolymerization of ethylene and propylene.

[0097] Formula A

[0098] Preparation process: The refined ethylene, propylene and solvent oil toluene are preheated to 70°C and then transferred to the loop reactor through a mass metering device. The intrinsic viscosity is detected in real time to control the reaction temperature, ethylene pressure and raw material ratio. After the polymerization reaction is stabilized, the mass feed ratio of olefin monomer and organic solvent is determined to be 8:92, wherein the mass ratio of ethylene to propylene is 25:75. The co-catalyst methylaluminoxane and catalyst A are sequentially added to the loop reactor. The reaction temperature is controlled at 100°C, the ethylene pressure is controlled at 2.0 MPa, wherein the molar ratio of the co-catalyst to catalyst A is Al:Ti=800, the polymer gel concentration is controlled at about 8%, and the polymerization reaction temperature of each section of the loop reactor is controlled by circulating cooling water.

[0099] The intrinsic viscosity was detected by the online viscosity detection device 1. The specific concentration viscosity of the glue was calculated to be 0.9404 dL / g, the actual viscosity was 2351 cps, and the viscosity average molecular weight was 4.9×10 4 g / mol, number average molecular weight is 15.3×10 4 g / mol. v =5.37×10 4 ×[η] 1.49 .

[0100] The elastomer glue flowing out of the liquid outlet A of the annular tube reactor is transferred to the flash tank. The first flash temperature maintains the glue temperature at 100°C, and the second flash temperature maintains the glue temperature at 120°C, increasing the glue concentration by 35%. The polymer glue after two flashes is transferred to the refining deashing system through a metering pump, and the glue is deashed. The pressure difference of the refining tower is maintained below 7MPa. The glue is transferred to the devolatilization granulation device. The process used is a dry deashing process. Through vacuum deashing, the first deashing temperature is controlled at 110°C and the speed is 90r / min; the second deashing temperature is controlled at 130°C and the speed is 70r / min; the third deashing temperature is controlled at 170°C and the speed is 40r / min, to prepare polyolefin elastomer 1, and its volatile organic matter content can be reduced to 50ppm.

[0101] Embodiment 2:

[0102] Reaction raw materials: Toluene is used as an organic solvent, and CGC metallocene catalyst is used as a transition metal catalyst, which is a catalyst B shown in the following formula B, wherein iBu is an isobutyl group. The product is a polyolefin elastomer 2 obtained by copolymerization of ethylene and octene.

[0103] Formula B

[0104] Preparation process: The refined ethylene, octene and solvent oil toluene are preheated to 70°C and then transferred to the loop reactor through a mass metering device. The intrinsic viscosity is detected in real time to control the reaction temperature, ethylene pressure and raw material ratio. After the polymerization reaction is stabilized, the mass feed ratio of olefin monomer and organic solvent is determined to be 10:90, wherein the mass ratio of ethylene to octene is 74:26. ​​The co-catalyst methylaluminoxane and catalyst B are added to the loop reactor in sequence. The reaction temperature is controlled at 110°C, the ethylene pressure is controlled at 1.5MPa, wherein the molar ratio of the co-catalyst to the main catalyst is Al:Ti=1000, the polymer gel concentration is controlled at about 10%, and the polymerization reaction temperature of each section of the loop reactor is controlled by circulating cooling water.

[0105] The intrinsic viscosity was detected by the online viscosity detection device 1. The specific concentration viscosity of the glue was calculated to be 1.0652 dL / g, the actual viscosity was 2700 cps, and the viscosity average molecular weight was 5.9×10 4 g / mol, and the number average molecular weight is 18.7×10 4 g / mol. v =5.37×10 4 ×[η] 1.49 .

[0106] The elastomer glue flowing out of the liquid outlet A of the annular tube reactor is transferred to the flash tank. The first flash temperature maintains the glue temperature at 110°C, and the second flash temperature maintains the glue temperature at 130°C, increasing the glue concentration by 30%. The polymer glue after two flashes is transferred to the refining deashing system through a metering pump, and the glue is deashed. The pressure difference of the refining tower is maintained below 7MPa, and the glue is transferred to the devolatilization granulation system. The process used is a dry deashing process, through vacuum one-stage, two-stage and multi-stage deashing, wherein the first deashing temperature is controlled at 120°C and the speed is 80r / min; the second deashing temperature is controlled at 140°C and the speed is 60r / min; the third deashing temperature is controlled at 180°C and the speed is 30r / min, to prepare polyolefin elastomer 2, and its VOC content can be reduced to 60ppm.

[0107] Embodiment 3:

[0108] Reaction raw materials: heptane is used as solvent, and a post-transition catalyst is used as catalyst, such as catalyst C shown in the following formula C. The product is vinyl polyolefin elastomer 3 (E-POE 3) obtained by homopolymerization of ethylene.

[0109] Formula C

[0110] Preparation process: The refined ethylene and solvent oil heptane are preheated to 60°C and then transferred to the loop reactor through a mass metering device. The intrinsic viscosity is detected in real time to control the reaction temperature, ethylene pressure and raw material ratio. After the polymerization reaction is stabilized, the mass ratio of ethylene and heptane is determined to be 10:90. The co-catalyst is sesquiethylaluminum and catalyst C, which are added to the loop reactor in sequence. The reaction temperature is controlled at 60°C, the ethylene pressure is controlled at 2.0MPa, wherein the molar ratio of the co-catalyst to the catalyst C is Al:Ti=1500, the concentration of the polymer glue is controlled at about 15%, and the polymerization reaction temperature of each section of the loop reactor is controlled by circulating cooling water.

[0111] The intrinsic viscosity was detected by the online viscosity detection device 1. The specific concentration viscosity of the glue was calculated to be 1.1013 dL / g, the actual viscosity was 2760 cps, and the viscosity average molecular weight was 6.2×10 4 g / mol, number average molecular weight is 19.3×10 4 g / mol. v =5.37×10 4 ×[η] 1.49 .

[0112] The elastomer glue flowing out of the liquid outlet A of the annular tube reactor is transferred to the flash tank. The first flash temperature maintains the glue temperature at 100°C, and the first flash glue temperature is maintained at 120°C, increasing the glue concentration by 40%. The polymer glue after two flashes is transferred to the refining deashing system through a metering pump, and the glue is deashed. The pressure difference of the refining tower is maintained below 7MPa, and the glue is transferred to the devolatilization granulation system. The process used is a dry deashing process, through vacuum one-stage, two-stage and multi-stage deashing, wherein the first deashing temperature is controlled at 110°C and the speed is 80r / min; the second deashing temperature is controlled at 130°C and the speed is 60r / min; the third deashing temperature is controlled at 170°C and the speed is 30r / min, to prepare E-POE polyolefin elastomer 3, and its VOC content can be reduced to 30ppm.

[0113] Figure 4 The hydrogen nuclear magnetic resonance spectrum of the polyolefin elastomer 3 prepared in Example 3 of the present invention is shown. Figure 4 As shown, it can be seen that the number of H atoms of carbon is the volume integrated by the nuclear magnetic hydrogen spectrum, the -CH3 displacement is between 0.8-1.1; and the -CH, -CH2 displacement is between 1.1-1.6. It is calculated that the branching degree of polyolefin elastomer 3 (vinyl polyolefin elastomer) prepared by the ring tube process is 74, which has good elasticity and plasticity and can be promoted in photovoltaic applications.

[0114] Embodiment 4:

[0115] Reaction raw materials: cyclohexane is used as solvent, and a late transition catalyst is used as catalyst, such as catalyst D shown in the following formula D, wherein X and Y are the same, both are chlorine. The product is vinyl polyolefin elastomer 4 (E-POE4) obtained by homopolymerization of ethylene.

[0116] Formula D

[0117] Preparation process: The refined ethylene and solvent oil cyclohexane are preheated to 40°C and then transferred to the loop reactor through a mass metering device. The intrinsic viscosity is detected in real time to control the reaction temperature, ethylene pressure and raw material ratio. After the polymerization reaction is stabilized, the mass ratio of ethylene and cyclohexane is determined to be 10:90. The co-catalyst is diethylaluminum monochloride and catalyst D are added to the loop reactor in sequence. The reaction temperature is controlled at 45°C and the ethylene pressure is controlled at 1.5MPa. The molar ratio of the co-catalyst to the catalyst D is Al:Ni=1000. The concentration of the polymer glue is controlled at about 10%. The polymerization reaction temperature of each section of the loop reactor is controlled by circulating cooling water.

[0118] The intrinsic viscosity was detected by the online viscosity detection device 1. The specific concentration viscosity of the glue was calculated to be 1.0408 dL / g, the actual viscosity was 2602 cps, and the viscosity average molecular weight was 5.7×10 4 g / mol, and the number average molecular weight is 16.7×10 4 g / mol. v =5.37×10 4 ×[η] 1.49 .

[0119] The elastomer glue flowing out of the liquid outlet A of the annular tube reactor is transferred to the flash tank. The first flash temperature maintains the glue temperature at 110°C, and the second flash temperature maintains the glue temperature at 120°C, increasing the glue concentration by 25%. The polymer glue after two flashes is transferred to the refining deashing system through a metering pump, and the glue is deashed. The pressure difference of the refining tower is maintained below 7MPa, and the glue is transferred to the devolatilization granulation system. The process used is a dry deashing process, through vacuum one-stage, two-stage and multi-stage deashing, wherein the first deashing temperature is controlled at 120°C and the speed is 80r / min; the second deashing temperature is controlled at 140°C and the speed is 60r / min; the third deashing temperature is controlled at 180°C and the speed is 30r / min, to prepare E-POE polyolefin elastomer 4, whose VOC content can be reduced to 40ppm.

[0120] Table 1 Relevant parameters of the glue in Examples 1 to 4

[0121]

[0122] As shown in Table 1, it can be seen that the online viscosity detection device 1 is set at the liquid outlet A of the loop reactor, and the intrinsic viscosity of the glue solution is detected by the online viscosity detection device 1, so that the actual viscosity and molecular weight of the glue solution can be obtained at the same time.

[0123] Table 2 below shows the relevant performance parameters of the polyolefin elastomers prepared in Examples 1 to 4. As shown in Table 2, it can be seen that the polyolefin elastomers prepared in the examples of the present invention have good tensile stress and strain resistance, high volume resistivity and good light transmittance, as well as good branching degree (60-85) and less ash content, and can be subsequently applied in technical fields such as photovoltaic encapsulation films and plastic reinforcement and toughening.

[0124] Table 2 Relevant performance parameters of polyolefin elastomers prepared in Examples 1 to 4

[0125]

[0126] Embodiment 5:

[0127] The preparation process of this Example 5 is substantially the same as that of Example 1, except that during the preparation process, the reaction temperature is controlled at 100° C., the ethylene pressure is controlled at 1.9 MPa, and the molar ratio of the co-catalyst to the catalyst A is Al:Ti=900.

[0128] The intrinsic viscosity was detected by the online viscosity detection device 1, and the specific concentration viscosity of the glue solution was calculated by the device to be 0.8206 dL / g, the actual viscosity was 2050 cps, the viscosity average molecular weight was 4.0×104 g / mol, and the number average molecular weight was 12.4×104 g / mol. Among them, Mv=5.37×104×[η]1.49.

[0129] By comparing Example 1 with Example 5, it can be seen that, based on the confirmation of the appropriate intrinsic viscosity in Example 1, the polymerization reaction can still be stabilized by adjusting the reaction temperature, ethylene pressure, and the molar ratio between the co-catalyst and the catalyst A. This shows that the detection of the intrinsic viscosity in the present invention is helpful for preparing a continuous solution of a polyolefin elastomer in a loop reactor.

[0130] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing polyolefin elastomer by solution polymerization using a loop process, characterized in that: include: Under anhydrous and oxygen-free conditions, olefin monomers, organic solvents, transition metal catalysts and co-catalysts are metered and fed into a loop reactor through multiple liquid inlets, and the temperature and pressure in the loop reactor are controlled to polymerize the olefin monomers to obtain a rubber solution containing a polyolefin elastomer; The intrinsic viscosity of the glue solution is detected in real time by an online viscosity detection device, and the viscosity of the glue solution in the loop reactor and the molecular weight of the polymerization product are determined at the same time, and at least one of the feed ratio, temperature and pressure is adjusted according to the detection results to achieve stabilization of the polymerization process; The loop reactor is an integrated double loop reactor, so that the reaction raw materials are in a fully mixed flow state; The inner diameter of the loop reactor is 20-80 cm, the height of the loop reactor is 7.5-75 m, and the total length of the flow path of the olefin monomer in the loop reactor is 30-300 m.

2. The method according to claim 1, characterized in that The online viscosity detection device is arranged at the liquid outlet of the loop reactor, and the online viscosity detection device comprises: Injection washing tube; A liquid storage ball, connected to the sample inlet and washing tube, and adapted to receive the glue solution from the sample inlet and washing tube; A buffer tube, partially sleeved inside the liquid storage ball, adapted to receive the glue from the liquid storage ball; and The measuring tube is connected to the bottom of the buffer tube and is arranged in parallel with the sample injection and washing tube and is suitable for measuring the viscosity of the glue solution from the buffer tube.

3. The method according to claim 2, characterized in that The online viscosity detection device also includes: A capillary tube, connected to the buffer tube and disposed above the buffer tube, adapted to regulate the flow rate of the glue solution; A measuring ball, connected to the capillary and arranged above the capillary, adapted to determine the viscosity of the glue and the molecular weight by the time it takes for the glue to flow through the measuring ball; The inner diameter of the capillary is 1-3 mm.

4. The method according to claim 1, characterized in that: The viscosity of the glue is 1000-5000cps.

5. The method according to claim 1, characterized in that When the olefin monomer is one kind, the mass ratio of the olefin monomer to the organic solvent is (5-50):(50-95).

6. The method according to claim 1, characterized in that The number average molecular weight of the polyolefin elastomer is (5-30)×10 4 g / mol; The viscosity average molecular weight of the polyolefin elastomer is (3-10)×10 4 g / mol.

7. The method according to claim 1, characterized in that The polymerization temperature is 20-150° C., the pressure is 0.1-15 MPa, and the time is 1-4 hours.

8. The method according to claim 1, characterized in that The method further comprises: The glue solution is sequentially subjected to dry devolatilization and granulation to obtain the polyolefin elastomer; Wherein, the temperature of the dry devolatilization is 150-300°C.

9. The method according to claim 1, characterized in that: The co-catalyst comprises at least one of alkyl aluminum, alkoxy aluminum, and alkyl aluminum halide; The olefin monomer includes at least one of ethylene, propylene, butene and hexene; The organic solvent includes at least one of pentane, hexane, heptane, cyclohexane and toluene; The transition metal catalyst comprises a homogeneous transition metal catalyst; The molar ratio of aluminum in the co-catalyst to the transition metal in the transition metal catalyst is (100-2000):1.

Images