Polyolefin elastomer devolatilization method applying steam stripping process

Abstract

The invention provides a polyolefin elastomer devolatilization method applying a steam stripping process, which comprises the following steps: mixing one or more of alpha-olefin, ethylene and a solvent to obtain a mixed solution; carrying out polymerization reaction on the mixed solution in a metallocene catalytic system or a non-metallocene catalytic system to obtain a polymer solution; and carrying out a devolatilization process on the polymer solution, wherein the devolatilization process comprises a steam stripping process. According to the present invention, the steam stripping process is introduced into the devolatilization process, such that the heating effect of the polymer solution is improved, and the devolatilization effect of the volatile component in the polymer solution is improved so as to reduce the volatile component in the polyolefin elastomer product to less than 300 ppm.

Description

Technical Field

[0001] The present invention relates to the technical field of POE preparation, and in particular to a method for devolatilization of polyolefin elastomer applying a stripping process. Background Art

[0002] Polyolefin elastomer (POE) is a thermoplastic elastomer prepared by solution polymerization process of ethylene and α-olefin. POE has excellent weather resistance, aging resistance, impact resistance and good processing performance.

[0003] The preparation method of POE product includes raw material preparation - polymerization reaction - devolatilization process - addition of additives - granulation and packaging in sequence. Among them, the devolatilization process is mainly used to remove volatile components after POE polymerization reaction such as unreacted monomers, solvents and low molecular oligomers. Therefore, the devolatilization process is the core link determining the quality, performance and production economy of POE products.

[0004] The devolatilization process of POE products includes two methods, dynamic devolatilization and static devolatilization. The two devolatilization methods mainly adopt surface renewal and heating methods to remove volatile components in the polymerization product. However, the surface renewal and heating effects will affect the devolatilization effect, making the volatile components in the polymerization product can only be removed by 99.5%, and it is still difficult to meet the index requirement that the volatile components in the polymerization product are <300 ppm in industrialization.

[0005] Therefore, to solve the above problems, it is of great significance to provide a devolatilization method to make the content of volatile components in POE products <300 ppm. Summary of the Invention

[0006] The technical problem solved by the present invention is to provide a method for devolatilization of polyolefin elastomer applying a stripping process. The devolatilization method provided by this application can reduce the volatile components in the polyolefin elastomer product to below 300 ppm.

[0007] In view of this, this application provides a method for devolatilization of polyolefin elastomer applying a stripping process, including the following steps:

[0008] Mix one or more of α-olefins, ethylene and a solvent to obtain a mixed solution;

[0009] Carry out a polymerization reaction on the mixed solution in a metallocene catalyst system or a non-metallocene catalyst system to obtain a polymer solution;

[0010] Carry out a devolatilization process on the polymer solution, and the devolatilization process includes a stripping process.

[0011] In some specific embodiments, the devolatilization process includes successively adding a stripping agent, performing primary static devolatilization, secondary static devolatilization, and tertiary static devolatilization. The dosage of the stripping agent is 0 to 30 wt% of the polymer solution and not equal to 0.

[0012] In some specific embodiments, the devolatilization process includes successively performing primary static devolatilization, adding a stripping agent, secondary static devolatilization, and tertiary static devolatilization. The dosage of the stripping agent is 0 to 30 wt% of the polymer solution in the previous stage and not equal to 0.

[0013] In some specific embodiments, the devolatilization process includes successively performing primary static devolatilization, secondary static devolatilization, adding a stripping agent, and tertiary static devolatilization. The dosage of the stripping agent is 0 to 30 wt% of the polymer solution in the previous stage and not equal to 0;

[0014] Or, the devolatilization process includes successively performing primary static devolatilization, secondary static devolatilization, tertiary static devolatilization, and adding a stripping agent. The dosage of the stripping agent is 0 to 30 wt% of the polymer solution in the previous stage and not equal to 0.

[0015] In some specific embodiments, the devolatilization process includes successively adding a stripping agent, flash evaporation, primary screw devolatilization, and secondary screw devolatilization; the addition amount of the stripping agent is 0 to 30 wt% of the polymer solution and not equal to 0.

[0016] In some specific embodiments, the devolatilization process includes successively performing flash evaporation, primary screw devolatilization, adding a stripping agent, and secondary screw devolatilization. The dosage of the stripping agent is 0 to 30 wt% of the polymer solution in the previous stage and not equal to 0;

[0017] Or, the devolatilization process includes successively performing flash evaporation, adding a stripping agent, primary screw devolatilization, and secondary screw devolatilization; the addition amount of the stripping agent is 0 to 30 wt% of the polymer solution in the previous stage and not equal to 0.

[0018] In some specific embodiments, the devolatilization process includes successively adding a stripping agent, a static devolatilization process, and a dynamic devolatilization process;

[0019] Or, the devolatilization process includes successively performing primary static devolatilization, adding a stripping agent, secondary static devolatilization, tertiary static devolatilization, and a dynamic devolatilization process;

[0020] Or, the devolatilization process includes successively performing primary static devolatilization, secondary static devolatilization, adding a stripping agent, tertiary static devolatilization, and a dynamic devolatilization process;

[0021] Or, the devolatilization process includes successively performing a static devolatilization process, adding a stripping agent, primary screw devolatilization, and secondary screw devolatilization;

[0022] Alternatively, the devolatilization process includes a static devolatilization process, a first-stage screw devolatilization, addition of a stripping agent, and a second-stage screw devolatilization that are carried out in sequence.

[0023] In some specific embodiments, heating the stripping agent is further included before adding the stripping agent, and the stripping agent is heated to 100 - 300 °C.

[0024] In some specific embodiments, the temperature of the stripping agent is 100 - 300 °C.

[0025] In some specific embodiments, the stripping agent includes steam, hot water, nitrogen, or carbon dioxide.

[0026] The present application provides a devolatilization method for a polyolefin elastomer using a stripping process. First, one or more of α-olefins, ethylene, and a solvent are mixed to obtain a mixed solution, then the mixed solution is subjected to a polymerization reaction to obtain a polymer solution, and finally the polymer solution is subjected to a devolatilization process, and a stripping process is introduced in the devolatilization process; by introducing the stripping process in the devolatilization process, the heating effect of the polymer solution is improved, and at the same time, the devolatilization effect of the volatile components in the polymer solution is also enhanced. Therefore, the introduction of the stripping process in the present application can reduce the volatile components in the polyolefin elastomer product to less than 300 ppm. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 One of the preparation devices for a polyolefin elastomer using a stripping process provided by the present invention;

[0028] Figure 2 Another preparation device for a polyolefin elastomer using a stripping process provided by the present invention;

[0029] Figure 3 A schematic diagram of the device for preparing a polyolefin elastomer product in Example 2 of the present invention;

[0030] Figure 4 A partial schematic diagram of the device for preparing a polyolefin elastomer product in Example 3 of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0031] To further understand the present invention, the preferred implementation schemes of the present invention will be described below in conjunction with embodiments. However, it should be understood that these descriptions are only for further explaining the features and advantages of the present invention, rather than limiting the claims of the present invention.

[0032] In view of the fact that the devolatilization process effect of POE products in the prior art can only reach 99.5%, which cannot meet the problem that the volatile content in POE products is < 300 ppm, the present application provides a preparation method of polyolefin elastomer using a stripping process. By introducing a stripping process, specifically introducing a stripping agent, in the devolatilization process, the heating effect of the polymer solution is improved, and at the same time, the devolatilization effect of the volatile components in the polymer solution is enhanced. Finally, the devolatilization effect is effectively improved, and the problems of difficult polymer heating and poor fluidity are solved. Further, the preparation method provided by the present application also reduces the requirements for heat exchangers and downstream devolatilization equipment for polymer devolatilization to a certain extent, reduces the construction cost of the preparation device and the difficulty of process operation. Specifically, the embodiments of the present invention disclose a devolatilization method of polyolefin elastomer using a stripping process, including the following steps:

[0033] Mix one or more of α-olefins, ethylene and a solvent to obtain a mixed solution;

[0034] Carry out a polymerization reaction on the mixed solution in a metallocene catalyst system or a non-metallocene catalyst to obtain a polymer solution;

[0035] Carry out a devolatilization process on the polymer solution, and the devolatilization process includes a stripping process.

[0036] In the devolatilization method of the polyolefin elastomer of the present application, in some specific embodiments, a polyolefin elastomer (POE) product is synthesized by a high-temperature solution polymerization process. First, ethylene and α-olefins are mixed in a solvent to obtain a mixed solution; this process is well-known to those skilled in the art, and the present application has no special restrictions on this; in some specific embodiments, the α-olefin can be selected from one or more of 1-butene, 1-hexene and 1-octene, and the solvent is n-hexane; in some specific embodiments, in the mixed solution, the concentration of n-hexane is 50-80 wt%, the concentration of ethylene is 8-30 wt%, and the concentration of α-olefin is 10-40 wt%.

[0037] The present application then carries out a polymerization reaction on the mixed solution in a metallocene or non-metallocene catalytic system to obtain a polymer solution; this process is a well-known step to those skilled in the art, and the present application has no special restrictions on this; the metallocene catalyst system is a well-known metallocene catalyst system to those skilled in the art, and the non-metallocene catalyst system is a well-known non-metallocene catalyst system to those skilled in the art, and the present application does not make special restrictions on this; in some specific embodiments, the above-mentioned mixed solution enters a reactor for polymerization reaction after mixing. One or more reactors can be used, the feeding temperature is -50 to 80 °C, and the reaction temperature is 80 to 220 °C.

[0038] After the above polymerization reaction, the polymer solution is subjected to a devolatilization process to remove volatile components after the POE polymerization reaction such as unreacted monomers, solvents, and low-molecular oligomers in the polymer solution; in the present application, a stripping process is introduced in the devolatilization process, that is, by introducing a stripping agent to strip the polymer solution, the heating effect and devolatilization effect of the polymer solution are increased; the addition of the stripping agent can be carried out in the dynamic devolatilization stage or in the static devolatilization stage.

[0039] In some specific embodiments, the devolatilization process includes sequentially adding a stripping agent, primary static devolatilization, secondary static devolatilization, and tertiary static devolatilization; specifically, a mixer is added after the POE polymerization reactor for mixing the stripping agent and the polymer solution, and the mixer can be a static mixer or a dynamic mixer, which ensures sufficient mixing of the stripping agent and the polymer solution, and then primary static devolatilization, secondary static devolatilization, and tertiary static devolatilization are carried out in sequence. The addition amount of the stripping agent is 0 to 30 wt% and not equal to 0 of the polymer solution, specifically, the addition amount of the stripping agent is 5 to 20 wt% of the polymer solution, and more specifically, the addition amount of the stripping agent is 10 to 15 wt% of the polymer solution.

[0040] In some specific embodiments, the devolatilization process includes sequentially primary static devolatilization, adding a stripping agent, secondary static devolatilization, and tertiary static devolatilization; the addition amount of the stripping agent is 0 to 30 wt% and not equal to 0 of the previous-stage polymer solution, specifically, the addition amount of the stripping agent is 5 to 20 wt% of the previous-stage polymer solution, and more specifically, the addition amount of the stripping agent is 10 to 15 wt% of the previous-stage polymer solution.

[0041] In a specific embodiment, in order to improve the devolatilization effect, adding low-boiling non-organic solvents such as steam, hot water, nitrogen, and carbon dioxide before the secondary static devolatilization, that is, secondary flashing, helps to improve the devolatilization effect and reduce the devolatilization cost. Adding hot water during flashing can improve the flashing volatile component effect, and at the same time can provide the stripping agent for the next-stage flashing to achieve an improved devolatilization effect, achieving a volatile residue < 300 ppm, directly reaching the product devolatilization effect and saving the screw devolatilization link; according to the device scale, secondary, tertiary, and quaternary static devolatilization can be set, but it does not affect the scope of use of this invention.

[0042] In some specific embodiments, the devolatilization process includes sequentially primary static devolatilization, secondary static devolatilization, adding a stripping agent, and tertiary static devolatilization; the addition amount of the stripping agent is 0 to 30 wt% and not equal to 0 of the previous-stage polymer solution, specifically, the addition amount of the stripping agent is 5 to 20 wt% of the previous-stage polymer solution, and more specifically, the addition amount of the stripping agent is 10 to 15 wt% of the previous-stage polymer solution.

[0043] In some specific embodiments, the devolatilization process includes primary static devolatilization, secondary static devolatilization, tertiary static devolatilization, and the addition of a stripping agent in sequence, that is, the stripping agent is added in an extruder; the addition amount of the stripping agent is 0 to 30 wt% of the previous-stage polymer solution and not equal to 0. Specifically, the addition amount of the stripping agent is 5 to 20 wt% of the previous-stage polymer solution. More specifically, the addition amount of the stripping agent is 10 to 15 wt% of the previous-stage polymer solution.

[0044] In the above examples, the stripping agent is added in the static devolatilization process; adding the stripping agent in each stage of the static devolatilization process can achieve heating of the polymer solution and stripping and flash evaporation to remove volatile components; however, the injection amount is different according to the heating effect and stripping effect required for each stage; since the amount of volatile components flashed off in the primary stage is large, the amount of stripping agent is also the largest, and correspondingly the amount in the tertiary stage is the smallest. If a medium with a relatively high boiling point such as water or steam is used as the stripping agent, it can be injected once in any stage of devolatilization. There is always a stripping agent remaining in the polymer until the polymer is formed during the devolatilization process; using a stripping agent with a relatively low boiling point such as nitrogen or carbon dioxide (low boiling point and fast flash evaporation) is preferably injected in the secondary or tertiary stage to enhance the devolatilization effect.

[0045] In the above description, the primary static devolatilization, secondary static devolatilization, and tertiary static devolatilization are respectively carried out in the first flash tank, the second flash tank, and the third flash tank; no special limitation is imposed on the specific implementation means thereof in this application.

[0046] Such as Figure 1 shown, Figure 1 is a schematic diagram of the device for preparing polyolefin elastomer products in this application. In the figure, 1 is the first reactor, 2 is the second reactor, 3 is the first flash tank, 4 is the second flash tank, 5 is the third flash tank, 6 is the extruder, and 7 is the stripping agent heater; ①, ②, ③, and ④ are respectively different addition points of the stripping agent.

[0047] In some specific embodiments, the devolatilization process includes the addition of a stripping agent, flash evaporation, primary screw devolatilization, and secondary screw devolatilization in sequence; the addition amount of the stripping agent is 0 to 30 wt% of the polymer solution and not equal to 0. Specifically, the addition amount of the stripping agent is 5 to 20 wt% of the polymer solution. More specifically, the addition amount of the stripping agent is 10 to 15 wt% of the polymer solution.

[0048] The devolatilization process includes flash evaporation, addition of a stripping agent, primary screw devolatilization, and secondary screw devolatilization in sequence; the dosage of the stripping agent is 0 to 30 wt% of the previous-stage polymer solution and not equal to 0. Specifically, the addition amount of the stripping agent is 5 to 20 wt% of the previous-stage polymer solution. More specifically, the addition amount of the stripping agent is 10 to 15 wt% of the previous-stage polymer solution.

[0049] Exemplarily, in a specific embodiment, the POE process uses a hexane system as a solvent. To improve the devolatilization effect, stripping agent steam or high-temperature water is added before the first-stage screw devolatilization to form an azeotrope of the solvent and water, reducing the boiling point to enhance the devolatilization effect. Since water or steam itself has a relatively high heat content, it can effectively heat the polymer solution, reducing the heating requirement of the polymer solution. In the mixing equipment or other operating equipment, only the heat preservation effect needs to be ensured, which greatly reduces the heating requirement during the devolatilization process. Adding hot water or steam to other solvent systems can also effectively reduce the solvent and monomer residues, and the remaining water can be used as the stripping agent for screw devolatilization, improving the devolatilization effect of the second-stage screw. The volatile content in the final product is reduced to less than 300 ppm. Since the direct contact between the stripping agent and the polymer solution greatly avoids the problem of polymer heating, and there is no need to worry about the solvent vaporization affecting the heat exchange effect due to too high heating temperature, effectively maintaining the fluidity of the polymer and reducing the conveying difficulty. This method is combined with the polymerization process (using hexane as a solvent). Due to the azeotropic effect of hexane and water, the boiling point of hexane is reduced to further enhance the devolatilization effect. And during separation, only cooling and static settling are required to achieve the separation effect.

[0050] It should be clear that external heat exchangers may not be required for heating before adding the stripping agent, or external media can be used for heating according to the process conditions. For example, if only low-temperature water is used as the stripping agent, external media need to be used for preheating in advance. Using different heating schemes does not affect the patent protection of this invention. The usage amount of the stripping agent can be effectively adjusted according to the required temperature control, and the preferred operation amount is < 50% of the polymer solution.

[0051] In some specific embodiments, the devolatilization process includes flash evaporation, first-stage screw devolatilization, adding a stripping agent, and second-stage screw devolatilization in sequence. The usage amount of the stripping agent is 0 - 30 wt% and not equal to 0 of the polymer solution in the previous stage. Specifically, the addition amount of the stripping agent is 5 - 20 wt% of the polymer solution in the previous stage. More specifically, the addition amount of the stripping agent is 10 - 15 wt% of the polymer solution in the previous stage.

[0052] In the above technical solution, the stripping agent is added in the dynamic devolatilization process. In the dynamic devolatilization scheme, the preparation device of the POE product is as Figure 2 shown, where 8 is the first reactor, 9 is the second reactor, 10 is the heater, 11 is the flash evaporation kettle, 12 is the first screw, and 13 is the second screw; ①, ②, ③, and ④ are different adding points of the stripping agent respectively.

[0053] Furthermore, in some specific embodiments, the devolatilization process further includes static devolatilization and dynamic devolatilization in sequence. On this basis, in some specific embodiments, the devolatilization process includes adding a stripping agent, static devolatilization process, and dynamic devolatilization process in sequence.

[0054] Or, the devolatilization process includes a primary static devolatilization, adding a stripping agent, a secondary static devolatilization, a tertiary static devolatilization, and a dynamic devolatilization process carried out in sequence;

[0055] Or, the devolatilization process includes a primary static devolatilization, a secondary static devolatilization, adding a stripping agent, a tertiary static devolatilization, and a dynamic devolatilization process carried out in sequence;

[0056] Or, the devolatilization process includes a static devolatilization process, adding a stripping agent, a primary screw devolatilization, and a secondary screw devolatilization carried out in sequence;

[0057] Or, the devolatilization process includes a static devolatilization process, a primary screw devolatilization, adding a stripping agent, and a secondary screw devolatilization carried out in sequence.

[0058] In the above devolatilization process, the dosage of the stripping agent is the same as that in the above scheme.

[0059] In the present application, the above stripping agent is mainly an inorganic gas steam, hot water, or a low-boiling non-organic solvent such as nitrogen or carbon dioxide. Specifically, the stripping agent is selected from steam, which has both heating and stripping effects. The above stripping agent is harmless and will not cause the polymer volatile content (VOCS) to exceed the standard even if it remains in the polymer; it will not react with the formed polymer and does not affect the performance of the polymer product; and it is easily vaporized under processing conditions (high temperature, low pressure) to escape from the polymer, causing the polymer to bubble and break, thereby carrying out organic volatiles; even if it enters the recovery system, it can be effectively separated.

[0060] The stripping agent described in the present application can be a stripping agent with a heating function or a stripping agent heated by an external medium, so as to effectively heat and raise the temperature of the polymer solution after mixing with the polymer solution. The temperature of the stripping agent is 150 - 300 °C. Specifically, the temperature of the stripping agent is 180 - 260 °C. More specifically, the temperature of the stripping agent is 200 - 240 °C. More specifically, the temperature of the stripping is 210 - 220 °C; the temperature of the stripping agent within the above range can raise the temperature of the polymer solution, reduce the dependence on the heater, and even eliminate the heater; the high-temperature addition of the stripping agent can avoid the problem that the temperature at the contact position of the polymer with the stripping agent cools down, affecting the mixing effect and even causing blockage of the filling pipeline.

[0061] The present application provides a method for devolatilization of polyolefin elastomer using a stripping process, which includes the following steps: mixing one or more of α-olefins, ethylene and a solvent to obtain a mixed solution; carrying out a polymerization reaction on the mixed solution in a metallocene catalyst system or a non-metallocene catalyst system to obtain a polymer solution; carrying out a devolatilization process on the polymer solution, and the stripping process is included in the devolatilization process; in the method for devolatilization of polyolefin elastomer provided by the present application, by introducing the stripping process in the devolatilization process, the introduction of the stripping process is equivalent to introducing a stripping agent in the devolatilization process, and the high-temperature stripping agent directly heats the polymer solution to raise the polymer temperature; specifically, during flash evaporation, the stripping agent carries a large amount of organic volatile components and escapes from the polymer, reducing the residual amount of organic volatile components under the condition of the same volatile component residue, and the inorganic stripping agent remains in the polymer and plays a role in the next-stage flash evaporation; due to the residue of the stripping agent in the polymer, it plays an effective bubbling role in the next-stage devolatilization (static devolatilization or dynamic devolatilization), enabling the organic volatile components to escape more fully. In the preparation process of POE of the present invention, the stripping method is used for devolatilization on the basis of the existing devolatilization process, effectively improving the devolatilization effect and solving the problems of difficult polymer heating and poor fluidity. The present invention reduces the requirements for heat exchangers and downstream devolatilization equipment for polymer devolatilization to a certain extent, reducing the device construction cost and the process operation difficulty.

[0062] In order to further understand the present invention, the following examples are used to illustrate in detail the method for devolatilization of polyolefin elastomer using a stripping process provided by the present invention. The protection scope of the present invention is not limited by the following examples.

[0063] Example 1

[0064] A mixed solution is prepared by mixing n-hexane, ethylene, α-olefin (1-butene) and a metallocene catalyst in a certain proportion: the n-hexane concentration is controlled at 60%, the ethylene is controlled at 14%, the α-olefin concentration is controlled at 26%, the reaction temperature is controlled at 150 °C, and the feed temperature is controlled at 20 °C;

[0065] The reaction materials are mixed and then enter the reactor for reaction. After the reaction, a polymer with a solid content of 15% is produced. At the reactor outlet, it is mixed with steam at 220 °C to raise the temperature of the polymer solution to 200 °C. The polymer solution after sufficient mixing and temperature increase is further heated to the temperature required for flash evaporation by a primary heat exchanger and then enters the dynamic devolatilization system for volatiles removal. The flash pressure is controlled at 0.4 Mpa. Most of the stripping agent, solvent, and monomer become gases and enter the raw material recovery system for separation and reuse. The polymer with a solid content of 80% at the outlet of the primary screw enters the secondary screw. At this time, the polymer contains the remaining part of the stripping agent and solvent. The remaining stripping agent accounts for 1% - 5% and continues to play a role in the next screw to cause the polymer to foam in the secondary screw and release a large amount of organic volatiles, which are removed from each vacuum port of the secondary extruder. Finally, the volatiles of the product are <500 ppm;

[0066] According to the above method, POE products are prepared under different conditions. The finally prepared POE products and control parameters are shown in Table 1;

[0067] Table 1 Performance data of relevant parameters and POE products in the examples

[0068]

[0069] Example 2

[0070] A mixed solution is prepared by mixing n-hexane, ethylene, α-olefin (1-butene), and metallocene catalyst in a certain proportion: the concentration of n-hexane is controlled at 60%, ethylene is controlled at 14%, the concentration of α-olefin is controlled at 26%, the reaction temperature is controlled at 150 °C, and the feeding temperature is controlled at 20 °C;

[0071] The reaction materials are mixed and then enter the reactor for reaction. After the reaction, a polymer with a solid content of 15% is produced. It is heated to the temperature required for flash evaporation by a primary heat exchanger and then enters the dynamic devolatilization system for volatiles removal. The flash pressure is controlled at 0.4 Mpa. Most of the solvent and monomer become gases and enter the raw material recovery system for separation and reuse. The polymer with a solid content of about 80% at the outlet of the primary screw enters the secondary screw. Hot water (stripping agent) at 120 °C is injected before the vacuum port of the secondary screw of the extruder, and the injection amount accounts for 0 - 5%. This causes the polymer to foam in the secondary screw and release a large amount of organic volatiles, which are removed from the vacuum port of the secondary extruder. To ensure that as few impurities as possible are introduced into the recovered raw materials, the injection port uses the last vacuum port before the end of the secondary extruder, and finally a POE product is obtained;

[0072] The preparation device of the POE product in this example is as Figure 3As shown in the figure, in the figure, 8 is the first reactor, 9 is the second reactor, 10 is the heater, 11 is the flash tank, 12 is the first screw, 13 is the second screw, 14 is the stripping agent heater, and 15 is the stripping agent storage tower;

[0073] The stripping is carried out under different conditions according to the above method to prepare the POE product. The finally prepared POE product and control parameters are shown in Table 1;

[0074] Table 2 Performance data table of relevant parameters and POE products in the examples

[0075]

[0076]

[0077] Example 3

[0078] A mixed solution is prepared by mixing n-hexane, ethylene, α-olefin (1-butene) and metallocene catalyst in a certain proportion: the n-hexane concentration is controlled at 60%, the ethylene is controlled at 14%, the α-olefin concentration is controlled at 26%, the reaction temperature is controlled at 150 °C, and the feed temperature is controlled at 20 °C;

[0079] After the reaction materials are mixed, they enter the reactor and react in the reactor. The polymer solid content after the reaction is 15%. After the first-stage and second-stage flash evaporation, the solid content reaches 90% before entering the third-stage flash evaporation. Before entering the heater inlet before the third-stage flash evaporation, high-pressure nitrogen is injected by a compressor for stripping flash evaporation. The mass ratio of the injected gas is 0-1.5%. The polymer is heated to 240 °C in the heater, and the vacuum degree is controlled at -0.09 Mpa. Finally, the POE product is obtained;

[0080] Figure 4 This is a schematic diagram of a partial device for preparing the POE product in this example. In the figure, 1 is the first reactor, 2 is the second reactor, 3 is the first flash tank, 4 is the second flash tank, 5 is the third flash tank, and 16 is the nitrogen compressor;

[0081] Table 3 Performance data table of relevant parameters and POE products in the examples

[0082]

[0083]

[0084] The description of the above examples is only used to help understand the method and its core idea of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and modifications can be made to the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

[0085] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the broadest scope consistent with the principles and novel features disclosed herein.

Claims

1. A devolatilization method of polyolefin elastomer using a stripping process, comprising the following steps: Mix one or more of α-olefins, ethylene and a solvent to obtain a mixed solution; Carry out a polymerization reaction on the mixed solution in a metallocene catalyst system or a non-metallocene catalyst system to obtain a polymer solution; Carry out a devolatilization process on the polymer solution, and the devolatilization process includes a stripping process.

2. The devolatilization method according to claim 1, wherein The devolatilization process includes sequentially adding a stripping agent, primary static devolatilization, secondary static devolatilization and tertiary static devolatilization. The dosage of the stripping agent is 0-30 wt% of the polymer solution and not equal to 0.

3. The devolatilization method according to claim 1, characterized in that, The devolatilization process includes sequentially carrying out primary static devolatilization, adding a stripping agent, secondary static devolatilization and tertiary static devolatilization. The dosage of the stripping agent is 0-30 wt% of the previous-stage polymer solution and not equal to 0.

4. The devolatilization method according to claim 1, wherein The devolatilization process includes sequentially carrying out primary static devolatilization, secondary static devolatilization, adding a stripping agent and tertiary static devolatilization. The dosage of the stripping agent is 0-30 wt% of the previous-stage polymer solution and not equal to 0; Or, the devolatilization process includes sequentially carrying out primary static devolatilization, secondary static devolatilization, tertiary static devolatilization and adding a stripping agent. The dosage of the stripping agent is 0-30 wt% of the previous-stage polymer solution and not equal to 0.

5. The devolatilization method according to claim 1, wherein The devolatilization process includes sequentially adding a stripping agent, flash evaporation, primary screw devolatilization and secondary screw devolatilization; the addition amount of the stripping agent is 0-30 wt% of the polymer solution and not equal to 0.

6. The devolatilization method according to claim 1, wherein, The devolatilization process includes sequentially carrying out flash evaporation, primary screw devolatilization, adding a stripping agent, and secondary screw devolatilization. The dosage of the stripping agent is 0-30 wt% of the previous-stage polymer solution and not equal to 0; Or, the devolatilization process includes sequentially carrying out flash evaporation, adding a stripping agent, primary screw devolatilization and secondary screw devolatilization; the dosage of the stripping agent is 0-30 wt% of the previous-stage polymer solution and not equal to 0.

7. The devolatilization method according to claim 1, wherein The devolatilization process includes sequentially adding a stripping agent, a static devolatilization process and a dynamic devolatilization process; Or, the devolatilization process includes sequentially carrying out primary static devolatilization, adding a stripping agent, secondary static devolatilization, tertiary static devolatilization and a dynamic devolatilization process; Or, the devolatilization process includes sequentially carrying out primary static devolatilization, secondary static devolatilization, adding a stripping agent, tertiary static devolatilization and a dynamic devolatilization process; Or, the devolatilization process includes sequentially carrying out a static devolatilization process, adding a stripping agent, primary screw devolatilization and secondary screw devolatilization; Or, the devolatilization process includes sequentially carrying out a static devolatilization process, primary screw devolatilization, adding a stripping agent and secondary screw devolatilization.

8. The devolatilization method according to any one of claims 2 to 7, characterized in that, Before adding the stripping agent, heating the stripping agent is also included, and the stripping agent is heated to 100-300 °C.

9. The devolatilization method according to any one of claims 2 to 7, characterized in that, The temperature of the stripping agent is 100-300 °C.

10. The devolatilization method according to any one of claims 1 to 7, characterized in that, The stripping agent includes steam, hot water, nitrogen or carbon dioxide.

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