Preparation method of polyolefin elastomer

Abstract

The present invention provides a method for preparing a polyolefin elastomer, belonging to the technical field of polyolefin production processes. The preparation method includes: under anhydrous and anaerobic conditions, stirring an olefin monomer, a main catalyst, and a cocatalyst in an organic solvent for a polymerization reaction to obtain a glue solution containing the polyolefin elastomer; subjecting the glue solution to ash removal and devolatilization through an n-stage screw and then extruding and granulating to prepare the polyolefin elastomer; wherein, n≥2 and n is an integer.

Description

Technical Field

[0001] The present invention relates to the technical field of polyolefin production processes, and particularly to a method for preparing a polyolefin elastomer. Background Art

[0002] In recent years, with the development of the photovoltaic industry, the demand for photovoltaic-grade thermoplastic polyolefin elastomers has been driven to increase. Photovoltaic-grade thermoplastic polyolefin elastomers have relatively high requirements for volume resistivity and light transmittance. Therefore, in the process of their production and manufacturing, attention needs to be paid to the removal of ash and volatile components.

[0003] In the related art, the common post-treatment process for polyolefin solution polymerization mainly uses an adsorbent to adsorb ash, and then removes volatile components through high-temperature flash evaporation, and finally extrudes and pelletizes. However, this process flow is complex, with high energy consumption. At the same time, the adsorption effect of the adsorbent is limited, resulting in relatively limited removal of ash and volatile components. Summary of the Invention

[0004] 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.

[0005] According to an embodiment of one aspect of the present invention, there is provided a method for preparing a polyolefin elastomer, the preparation method comprising: under anhydrous and anaerobic conditions, stirring an olefin monomer, a main catalyst, and a co-catalyst in an organic solvent to carry out a polymerization reaction to obtain a glue solution containing a polyolefin elastomer; subjecting the glue solution to ash removal and volatile removal through an n-stage screw and then extruding and pelletizing to prepare a polyolefin elastomer; wherein, n≥2 and n is an integer.

[0006] According to an embodiment of the present invention, n≤4; the temperature of the n-stage screw is 20~220°C, and the rotation speed is 20~200 rpm.

[0007] According to an embodiment of the present invention, a twin screw is used in each stage of the n-stage screw, and an inert gas delivery unit for injecting an inert gas into the screw and a degassing unit for removing gas from the glue solution are configured.

[0008] According to an embodiment of the present invention, a reagent is added respectively in each stage of the n-stage screw; the reagent includes at least one of water, an aqueous solution of an acid, and an aqueous solution of a base.

[0009] According to an embodiment of the present invention, in the case where the added reagent is an aqueous solution of an acid or an aqueous solution of a base, each also includes a process of adding a counter reagent (i.e., an aqueous solution of a base or an aqueous solution of an acid).

[0010] According to an embodiment of the present invention, the mass fraction of the aqueous solution of the acid is 0.1 to 10%; the mass fraction of the aqueous solution of the base is 0.1 to 10%; the volume of the aqueous solution of the acid is 0.01 to 1% of the volume of the organic solvent in the colloidal solution; the volume of the aqueous solution of the base is 0.01 to 1% of the volume of the organic solvent in the colloidal solution; the volume of water is 10 to 100% of the volume of the organic solvent in the colloidal solution.

[0011] According to an embodiment of the present invention, the rotation speed of the first-stage screw is 20 to 30 rpm, and the temperature is 20 to 40 °C; the rotation speed of the nth-stage screw is 110 to 130 rpm, and the temperature is 180 to 200 °C.

[0012] According to an embodiment of the present invention, the rotation speed of the second-stage screw to the (n-1)th-stage screw is 40 to 60 rpm, and the temperature is 20 to 40 °C.

[0013] According to an embodiment of the present invention, the organic solvent includes at least one of isobutane, n-pentane, isopentane, n-hexane, methylcyclopentane, n-heptane, methylcyclohexane, isooctane, toluene; the olefin monomer includes at least one of ethylene, C3~C 20 α-olefins; the main catalyst includes at least one of metallocene catalysts, α-diimine nickel catalysts; the cocatalyst includes at least one of triethylaluminum, triisobutylaluminum, trihexylaluminum, trioctylaluminum, diethylaluminum chloride, dichloroethylaluminum, methylaluminoxane, modified methylaluminoxane, perfluorophenylboron, triphenylcarbenium tetrakis(pentafluorophenyl)borate, N,N-dimethylanilinium tetrakis(pentafluorophenyl)borate, N,N-di(hexadecyl)anilinium tetrakis(pentafluorophenyl)borate.

[0014] According to an embodiment of the present invention, the temperature of the polymerization reaction is 60 to 200 °C, the pressure is 1 to 10 MPa, and the time is 5 to 60 min; C3~C 20 α-olefins include at least one of propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-decene, 1-dodecene, 1-hexadecene, 1-octadecene, 1-eicosene.

[0015] According to an embodiment of the present invention, the ash content of the polyolefin elastomer is ≤50 ppm, and the volatile content is ≤50 ppm.

[0016] According to an embodiment of the present invention, the present invention uses an n-stage screw for ash removal and volatile removal (i.e., removing ash and removing volatile components), which can effectively remove unreacted monomers, residual catalysts used, and remove volatile impurities, improving the quality of the polyolefin elastomer. The polyolefin elastomer with ash and volatile removed is colorless and transparent, effectively improving the light transmittance of the polyolefin elastomer. In addition, due to the use of the n-stage screw, it can provide more sufficient mixing and shearing for the polyolefin elastomer, which is beneficial to forming a more uniform polyolefin elastomer structure, and the extrusion granulation process can directly convert the treated rubber solution into granular polyolefin elastomer, simplifying the production process flow, improving production efficiency, and facilitating subsequent storage and transportation. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 FIG. shows a flowchart of a method for preparing a polyolefin elastomer according to an embodiment of the present invention;

[0018] Figure 2 FIG. shows a schematic structural diagram of each stage of the n-stage screw according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0019] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are merely exemplary and are not intended to limit the scope of the present invention. In the following detailed description, for the sake 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 can be implemented without these specific details. In addition, in the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessarily confusing the concepts of the present invention.

[0020] The terms used herein are merely for describing specific embodiments and are not intended to limit the present invention. The term "including" used herein indicates the presence of features, steps, operations, but does not exclude the presence or addition of one or more other features.

[0021] In the field of photovoltaic applications, the demand for polyolefin elastomers continues to increase. When applied in the photovoltaic field, it is required that the polyolefin elastomer has a high volume resistivity and good light transmittance at the same time, which requires attention to the removal effect of ash and volatile components in the post-treatment process of preparing the polyolefin elastomer. The commonly used adsorbent adsorption method mentioned in the background technology has high energy consumption, limited adsorption capacity of the adsorbent, and requires replacement of the adsorbent, and the process flow is relatively complex.

[0022] In view of this, the present invention provides a method for preparing a polyolefin elastomer, Figure 1 FIG. shows a flowchart of a method for preparing a polyolefin elastomer according to an embodiment of the present invention, as Figure 1As shown, the preparation method includes operations S101~S102.

[0023] In operation S101, under anhydrous and oxygen-free conditions, olefin monomers, a main catalyst, and a co-catalyst are stirred in an organic solvent for polymerization reaction to obtain a rubber solution containing a polyolefin elastomer.

[0024] According to the embodiments of the present invention, the anhydrous and oxygen-free conditions can avoid the interference of moisture and oxygen on the polymerization reaction, and improve the purity and quality of the polyolefin elastomer in the glue. The olefin monomer can be understood as one olefin monomer or a mixture of multiple olefin monomers.

[0025] In operation S102, the rubber solution is deashed and devolatilized through an n-stage screw and then extruded and granulated to prepare a polyolefin elastomer, wherein n≥2, n is an integer, such as 2, 3, 4, 5, etc.

[0026] According to the embodiment of the present invention, deashing and devolatilization are performed by an n-stage screw, so that unreacted monomers, main catalyst, co-catalyst residues and other volatile impurities can be effectively removed, which helps to improve the quality of polyolefin elastomers.

[0027] According to an embodiment of the present invention, each stage of the n-stage screw adopts a twin screw and is provided with an inert gas delivery unit for injecting inert gas into the screw and a degassing unit for removing gas from the glue solution.

[0028] Figure 2 The schematic diagram of the structure of each screw in the n-stage screw of the embodiment of the present invention is shown. The structure of each screw is as follows Figure 2 As shown, the n-stage screw can be understood as each stage of the screw being connected in series. Each stage of the screw includes a transmission unit 1, a twin screw 2, an inert gas conveying unit 3, and a degassing unit 4 distributed at different positions. The degassing unit 4 can be set to multiple as needed, such as 6 as shown in the figure. The transmission unit 1 is connected to one end of the twin screw 2, and the transmission unit 1 is suitable for providing power to the twin screw 2, transmitting the power to the twin screw 2 to rotate it, and adjusting the mixing degree and conveying speed of the glue by adjusting the rotation speed of the twin screw 2. The twin screw 2 applies shear force to the material through the relative movement between the screws, promotes the mixing of the material, and reduces the residual impurities. The inert gas conveying unit 3 is connected to the other end (upstream end) of the twin screw 2, and is suitable for injecting inert gas into the screw, which helps to maintain an oxygen-free environment for the screw, prevents the oxidation degradation of the polyolefin elastomer, and also helps to carry volatile substances out of the screw. The degassing units 4 are respectively arranged at different positions downstream of the inert gas conveying unit 3, which helps to remove gases in the glue solution, such as unreacted monomers, solvents and other volatile components, thereby reducing the volatile matter and improving the purity of the polyolefin elastomer.

[0029] According to an embodiment of the present invention, the present invention realizes direct extrusion granulation after deashing and devolatilization by first performing a polymerization reaction and then directly entering an n-stage screw, making the production process relatively simple, with low energy consumption, and having a better effect on removing ash and volatile components, and being able to achieve the preparation of polyolefin elastomers adapted to photovoltaics.

[0030] According to an embodiment of the present invention, the ash content of the polyolefin elastomer is ≤50 ppm, and the volatile content is ≤50 ppm. By setting an n-stage screw for deashing and devolatilization, not only the production process is simplified, but also the removal effect of ash and volatile components in the polyolefin elastomer can be optimized, the qualified rate of the polyolefin elastomer is improved, and it is more suitable for fields with high requirements for light transmittance such as photovoltaics.

[0031] It should be noted that the temperature and rotation speed of each stage of the n-stage screw can be set separately according to needs, which is beneficial to achieving a better effect of removing ash and volatile components.

[0032] According to an embodiment of the present invention, n ≤ 4, for example, it can be 2, 3, or 4, preferably 3 or 4. The temperature of the n-stage screw is 20~220 °C, for example, it can be 20 °C, 50 °C, 80 °C, 100 °C, 130 °C, 150 °C, 180 °C, 200 °C, or 220 °C, and the rotation speed is 20~200 rpm, for example, it can be 20 rpm, 50 rpm, 100 rpm, 150 rpm, or 200 rpm. Adjusting the number of the n-stage screw, the temperature of each stage of the screw, and the rotation speed within a suitable range can achieve sufficient removal of ash and volatile components before extrusion granulation, and the temperature and rotation speed of each stage of the screw can be adjusted independently, and can be adaptively adjusted according to different requirements of the prepared products, with a wider adaptation range.

[0033] According to an embodiment of the present invention, a reagent is added to each stage of the n-stage screw respectively; the reagent includes at least one of water, an aqueous solution of an acid, and an aqueous solution of a base. The water can be, for example, deionized water. The addition of water helps to dissolve soluble impurities therein, such as incompletely reacted catalyst residues or water-soluble by-products, helps to clean the colloidal solution, and can also carry away some volatile substances when the water evaporates, assisting the devolatilization process. The aqueous solution of an acid can neutralize residual basic substances, such as when the used catalyst has basicity. At the same time, the acid can also react with metal ions to form compounds that are easier to remove, helping to reduce the ash content. The action mechanism of the aqueous solution of a base is similar to that of the aqueous solution of an acid, and it also has the effect of neutralizing residual acidic substances. In addition, for metal salt catalysts, alkaline conditions help the metal salt catalysts to deactivate and avoid unnecessary side reactions. By adding the reagent, it helps to make the polyolefin elastomer easier to perform subsequent processing steps such as molding and extrusion granulation.

[0034] According to an embodiment of the present invention, when the added reagent is an aqueous solution of an acid or an aqueous solution of a base, each further includes a step of adding a counter reagent (an aqueous solution of a base or an aqueous solution of an acid).

[0035] The counter reagent can be understood as follows: when the actually added reagent is an aqueous solution of an acid, an aqueous solution of a base is added subsequently to neutralize the aqueous solution of the acid introduced in the previous process. Or it can be understood that when the actually added reagent is an aqueous solution of a base, an aqueous solution of an acid is added subsequently to neutralize the aqueous solution of the base introduced in the previous process. This enables the prepared polyolefin elastomer to be in a pH environment close to neutral, which helps to maintain the stability of the polyolefin elastomer. By alternately using acidic and basic conditions, inorganic ash and other volatile components can be removed more effectively, which helps to better separate different types of impurities.

[0036] For example, when the n-stage screw used is a 2-stage screw, water can be used as the reagent in the first-stage screw, and extrusion granulation can be carried out in the second-stage screw.

[0037] When the n-stage screw used is a 3-stage screw, water can be used as the reagent in the first-stage screw and the second-stage screw, and extrusion granulation can be carried out in the third-stage screw; alternatively, an acid solution can be used as the reagent in the first-stage screw, a base solution can be used as the reagent in the second-stage screw, and extrusion granulation can be carried out in the third-stage screw; or a base solution can be used as the reagent in the first-stage screw, an acid solution can be used as the reagent in the second-stage screw, and extrusion granulation can be carried out in the third-stage screw.

[0038] When the n-stage screw used is a 4-stage screw, an acid solution can be used as the reagent in the first-stage screw, water can be used as the reagent in the second-stage screw, a base solution can be used as the reagent in the third-stage screw, and extrusion granulation can be carried out in the fourth-stage screw; alternatively, a base solution can be used as the reagent in the first-stage screw, water can be used as the reagent in the second-stage screw, an acid solution can be used as the reagent in the third-stage screw, and extrusion granulation can be carried out in the fourth-stage screw; or water can be used as the reagent in the first-stage screw to the third-stage screw, and extrusion granulation can be carried out in the fourth-stage screw.

[0039] According to the embodiments of the present invention, the mass fraction of the aqueous solution of acid and / or the aqueous solution of base is 0.1 - 10% respectively. For example, it can be 0.1%, 0.5%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9% or 10%, and preferably 1 wt%. The volume of the aqueous solution of acid and / or the aqueous solution of base is 0.01 - 1% of the organic solvent in the glue solution. For example, it can be 0.01%, 0.05%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9% or 1%; the volume of water is 10 - 100% of the organic solvent in the glue solution. For example, it can be 10%, 50% or 100%. The aqueous solution of acid can be any commercially available strong acid or weak acid, such as hydrochloric acid solution, sulfuric acid solution, etc. The aqueous solution of base can be any commercially available strong base or weak base, such as sodium hydroxide solution or potassium hydroxide solution, etc. Adjusting the types and mass fractions of the aqueous solution of acid or the aqueous solution of base within the above ranges can effectively remove ash and volatile components, and at the same time, it will not affect the properties of the polyolefin elastomer due to the addition of too concentrated solutions.

[0040] According to the embodiments of the present invention, the rotation speed of the first-stage screw is 20 - 30 rpm. For example, it can be 20 rpm, 25 rpm or 30 rpm, and preferably 20 rpm. The temperature is 20 - 40 °C. For example, it can be 20 °C, 30 °C or 40 °C, and preferably 30 °C. The rotation speed of the nth-stage screw is 110 - 130 rpm. For example, it can be 110 rpm, 120 rpm or 130 rpm, and preferably 120 rpm. The temperature is 180 - 200 °C. For example, it can be 180 °C, 190 °C or 200 °C, and preferably 190 °C.

[0041] At the first-stage screw, a lower temperature and a lower rotation speed are used, that is, a slower material conveying speed and a longer residence time, which are beneficial to fully mix the glue solution and the reagent, improve the removal effect of ash, and in addition, the lower rotation speed corresponds to a lower shear effect, which can reduce the damage to the polymer segments in the polyolefin elastomer. The lower temperature avoids pyrolysis or unnecessary side reactions. At the nth-stage screw, a higher rotation speed and a higher temperature are used to extrude and pelletize the polyolefin elastomer, and at the same time, it has an accelerating effect on the removal of ash and volatile components, thereby realizing the refining of the polyolefin elastomer.

[0042] According to the embodiments of the present invention, the rotation speed of the second-stage screw to the (n - 1)th-stage screw is 40 - 60 rpm. For example, it can be 40 rpm, 50 rpm or 60 rpm, and preferably 50 rpm. The temperature is 20 - 40 °C. For example, it can be 20 °C, 30 °C or 40 °C, and preferably 30 °C.

[0043] The second-stage screw to the (n - 1)-th stage screw play a transitional role, ensuring the process of the glue liquid transitioning from preliminary treatment to final extrusion granulation. Compared with the first-stage screw, the second-stage screw to the (n - 1)-th stage screw speeds up the conveying speed of the glue liquid, but the temperature still remains within a moderate range to avoid the influence of excessive shear on the structure of the polyolefin elastomer, which helps to further homogenize the material and promotes the dispersion of ash and polyolefin elastomer, enabling better removal of ash and volatile matter after the polyolefin elastomer passes through the n-stage screw.

[0044] According to an embodiment of the present invention, the organic solvent includes at least one of isobutane, n-pentane, isopentane, n-hexane, methylcyclopentane, n-heptane, methylcyclohexane, isooctane, toluene, preferably at least one of n-hexane, methylcyclopentane, n-heptane, and more preferably n-hexane or n-heptane. The olefin monomer includes ethylene, C3-C 20 α-olefins, for example, can be copolymerization of ethylene, or homopolymerization of ethylene and α-olefins, preferably ethylene. The main catalyst includes at least one of metallocene catalysts and α-diimine nickel catalysts. The concentration of the main catalyst in the reaction vessel (such as a reaction kettle) is 1 - 100 μmol / L, preferably 20 μmol / L. The cocatalyst includes at least one of triethylaluminum, triisobutylaluminum, trihexylaluminum, trioctylaluminum, diethylaluminum chloride, dichloroethylaluminum, methylaluminoxane, modified methylaluminoxane, perfluorophenylboron, triphenylcarbenium tetrakis(pentafluorophenyl)borate, N,N-dimethylanilinium tetrakis(pentafluorophenyl)borate, N,N-di(hexadecyl)anilinium tetrakis(pentafluorophenyl)borate. The concentration of the cocatalyst in the reaction vessel (such as a reaction kettle) is 50 - 2000 μmol / L, preferably 2000 μmol / L.

[0045] According to an embodiment of the present invention, the temperature of the polymerization reaction is 60 - 200 °C, for example, it can be 60 °C, 80 °C, 100 °C, 120 °C, 140 °C, 160 °C, 180 °C or 200 °C, preferably 80 °C. The pressure is 1 - 10 MPa, for example, it can be 1 MPa, 3 MPa, 5 MPa, 7 MPa, 9 MPa or 10 MPa, preferably 3 MPa. The time is 5 - 60 min, for example, it can be 5 min, 10 min, 20 min, 30 min, 40 min, 50 min or 60 min, preferably 30 min. C3-C 20 α-olefins include at least one of propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-decene, 1-dodecene, 1-hexadecene, 1-octadecene, 1-eicosene.

[0046] The properties of the polyolefin elastomer prepared by the preparation method of the present invention can reach the following indicators: the degree of branching is 60 - 80, measured by high-temperature nuclear magnetic resonance, the reagent is deuterated tetrachloroethane, and the value represents the number of branched chains in 1000 carbons. The volatile matter is ≤100 ppm, and the volatile matter is tested according to GB / T 24131.2 - 2017. The ash content is ≤100 ppm, and the ash content is tested according to GB / T 9345.1 - 2008. The hardness is 55 - 70 Shore A, and the hardness is tested according to GB / T 2411 - 2008. The tensile strength is ≥4 MPa, and the tensile strength is tested according to GB / T1040.3 - 2006. The melt index is 0.5 - 30, and the melt index is tested according to GB / T3682.1 - 2018, the temperature is 190 °C, and the load is 2.16 kg. The weight-average molecular weight is M w is 200,000 - 400,000, the molecular weight distribution PDI is 1.5 - 2.5, the weight-average molecular weight M w and the molecular weight distribution PDI are tested according to SN / T 4183 - 2015. The melting point T m is 55 - 70 °C, the density is 0.860 - 0.880 g / cm 3 , and the density is tested according to GB / T1033.1 - 2008. The volume resistivity is ≥1×10 17 Ω·cm, and the volume resistivity is tested according to GB / T31838.2 - 2019. The light transmittance is ≥92.0%, and the light transmittance is tested according to GB / T2410 - 2008.

[0047] The present invention will be further illustrated below through examples, drawings, and related test experiments and their results. In the following detailed description, for the sake 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 can also be implemented without these specific details. Moreover, without conflict, the details in the following embodiments can be arbitrarily combined into other feasible embodiments.

[0048] It should be noted that the following specific embodiments are only for illustration purposes, and the protection scope of the present invention is not limited thereto. The chemical drugs and raw materials used in the following embodiments are all obtained commercially or prepared by recognized treatment methods. Each stage of the n-stage screw used in the following embodiments has the structure as Figure 2 shown.

[0049] Example 1:

[0050] The preparation process of the polyolefin solution polymerization is as follows:

[0051] Polymerization reaction: Ethylene, nickel diimine catalyst, and triethylaluminum were thoroughly stirred in n-hexane to carry out a polymerization reaction for 30 min. The polymerization temperature was 80 °C, the polymerization pressure was 3 MPa, the concentration of the nickel diimine catalyst was 20 μmol / L, the concentration of triethylaluminum was 2000 μmol / L, and the volume of n-hexane was 7 L to obtain a polyolefin latex.

[0052] Post-treatment of the latex: A 4-stage screw was selected. The rotation speed of the first-stage screw was 20 rpm, the temperature was 30 °C, and 100 ml of hydrochloric acid aqueous solution (1 wt% concentration) was added; the rotation speed of the second-stage screw was 50 rpm, the temperature was 30 °C, and 5 L of deionized water was added; the rotation speed of the third-stage screw was 50 rpm, the temperature was 30 °C, and 100 ml of NaOH aqueous solution (1 wt% concentration) was added; the rotation speed of the fourth-stage screw was 120 rpm, the temperature was 190 °C, and extrusion granulation was carried out to obtain polyolefin elastomer particles 1.

[0053] Example 2:

[0054] The preparation process of solution polymerization of polyolefin is as follows:

[0055] Polymerization reaction: Ethylene, nickel diimine catalyst, and triethylaluminum were thoroughly stirred in n-hexane to carry out a polymerization reaction for 30 min. The polymerization temperature was 80 °C, the polymerization pressure was 3 MPa, the concentration of the nickel diimine catalyst was 20 μmol / L, the concentration of triethylaluminum was 2000 μmol / L, and the volume of n-hexane was 7 L to obtain a polyolefin latex.

[0056] Post-treatment of the latex: A 4-stage screw was selected. The rotation speed of the first-stage screw was 20 rpm, the temperature was 30 °C, and 100 ml of NaOH aqueous solution (1 wt% concentration) was added; the rotation speed of the second-stage screw was 50 rpm, the temperature was 30 °C, and 5 L of deionized water was added; the rotation speed of the third-stage screw was 50 rpm, the temperature was 30 °C, and 100 ml of HCl aqueous solution (1 wt% concentration) was added; the rotation speed of the fourth-stage screw was 120 rpm, the temperature was 190 °C, and extrusion granulation was carried out to obtain polyolefin elastomer particles 2.

[0057] Example 3:

[0058] The preparation process of solution polymerization of polyolefin is as follows:

[0059] Polymerization reaction: Ethylene, nickel diimine catalyst, and triethylaluminum were thoroughly stirred in n-hexane to carry out a polymerization reaction for 30 min. The polymerization temperature was 80 °C, the polymerization pressure was 3 MPa, the concentration of the nickel diimine catalyst was 20 μmol / L, the concentration of triethylaluminum was 2000 μmol / L, and the volume of n-hexane was 7 L to obtain a polyolefin latex.

[0060] Post-treatment of the glue solution: Select a 3-stage screw. The rotation speed of the first-stage screw is 20 rpm, the temperature is 30 °C, and 100 ml of hydrochloric acid aqueous solution (1 wt% concentration) is added; the rotation speed of the second-stage screw is 50 rpm, the temperature is 30 °C, and 100 ml of NaOH aqueous solution (1 wt% concentration) is added; the rotation speed of the third-stage screw is 120 rpm, the temperature is 190 °C, and extrusion granulation is carried out to obtain polyolefin elastomer particles 3.

[0061] Example 4:

[0062] The preparation process of solution polymerization of polyolefin is as follows:

[0063] Polymerization reaction: Ethylene, diimine nickel catalyst, and triethylaluminum are fully stirred evenly in n-hexane for a polymerization reaction for 30 min. The polymerization temperature is 80 °C, the polymerization pressure is 3 MPa, the concentration of the diimine nickel catalyst is 20 μmol / L, the concentration of triethylaluminum is 2000 μmol / L, and the volume of n-hexane is 7 L to obtain a polyolefin glue solution.

[0064] Post-treatment of the glue solution: Select a 3-stage screw. The rotation speed of the first-stage screw is 50 rpm, the temperature is 30 °C, and 5 L of deionized water is added; the rotation speed of the second-stage screw is 50 rpm, the temperature is 30 °C, and 5 L of deionized water is added; the rotation speed of the third-stage screw is 120 rpm, the temperature is 190 °C, and extrusion granulation is carried out to obtain polyolefin elastomer particles 4.

[0065] Example 5

[0066] The preparation process of solution polymerization of polyolefin is as follows:

[0067] Polymerization reaction: Ethylene, metallocene constrained geometry catalyst (CGC), and methylaluminoxane are fully stirred evenly in n-heptane for a polymerization reaction for 15 min. The polymerization temperature is 130 °C, the polymerization pressure is 4 MPa, the concentration of the metallocene CGC catalyst is 10 μmol / L, the concentration of methylaluminoxane is 2000 μmol / L, and the volume of n-heptane is 7 L to obtain a polyolefin glue solution.

[0068] The post-treatment process of the glue solution in this Example 5 is the same as that in Example 1 and will not be elaborated here, and polyolefin elastomer particles 5 are prepared.

[0069] Comparative Example 1

[0070] The preparation process of traditional solution polymerization of polyolefin is as follows:

[0071] Polymerization reaction: Ethylene, nickel diimine catalyst, and triethylaluminum were thoroughly stirred evenly in n-hexane for 30 min. The polymerization temperature was 80 °C, the polymerization pressure was 3 MPa, the concentration of the nickel diimine catalyst was 20 μmol / L, the concentration of triethylaluminum was 2000 μmol / L, and the volume of n-hexane was 7 L to obtain a polyolefin rubber solution.

[0072] Post-treatment of the rubber solution: The rubber solution from the polymerization kettle was deashed using adsorption deashing. The adsorbent was 3A molecular sieve, with a pressure of 3 MPa and a temperature of 170 °C. The deashed rubber solution entered the devolatilization unit and passed through two series-connected flash tanks. The flash temperatures of both flash tanks were 170 °C, the pressures in the flash tanks were both 0.1 MPa, and the stirring forms in the flash tanks were both single screw ribbon stirring. The residence times of the rubber solution in the first and second flash tanks were 10 min and 20 min, respectively. The material after two flashings was pumped to a single-screw extruder for extrusion granulation. The screw speed was 110 rpm / min, and the screw temperature was controlled at 190 °C to obtain polyolefin elastomer particles 1'.

[0073] The polyolefin elastomer particles prepared in Examples 1 to 5 and Comparative Example 1 were tested according to national standards respectively, and the test results are shown in Table 1 below.

[0074] Table 1 Performance Test of Vinyl Polyolefin Elastomer

[0075]

[0076] By comparing Comparative Example 1 with Example 1, it can be found that compared with the traditional post-treatment method, the polyolefin elastomer particles prepared by the n-stage screw have high purity, extremely low ash and volatile residue, high volume resistivity and light transmittance. By comparing Example 1 with Example 2, it can be found that the addition order of the acid solution and the alkali solution can be interchanged, which has basically no overall impact on the performance of the polyolefin elastomer particles, and there is basically no difference in volatiles and volatile components. By comparing Example 1 with Example 3, it can be found that when reducing the 1-stage screw, the performance of the polyolefin elastomer particles remains unchanged, but the volatile content slightly increases and the ash content remains unchanged. By comparing Example 3 with Example 4, it can be found that only deionized water is used in the screw, which basically does not affect the performance of the polyolefin elastomer particles, the volatile content remains basically unchanged, and the ash content slightly increases. By comparing Example 1 with Example 5, it can be found that under the metallocene catalyst system, the performance of the polyolefin elastomer particles changes, but the ash and volatile components remain basically unchanged. Therefore, the preparation method of the present invention is applicable not only to the nickel diimine-based catalytic system but also to the metallocene catalyst system.

[0077] The rubber solution was sampled at the sampling port of the reaction kettle (before entering the n-stage screw), and its performance was tested after rotary evaporation and drying. The test results are shown in Table 2 below.

[0078] Table 2 Performance Test of Samples at the Sampling Ports of Reactors in Examples 1 - 5

[0079]

[0080] As shown in Table 2, it can be found from the test results that the ash content and volatile content of the polyolefin elastomer without passing through the n - stage screw are more than 5 times higher than those passing through the n - stage screw, the volume resistivity is about 2 orders of magnitude lower, and the light transmittance is reduced by more than 4%. This shows that the n - stage screw has a good effect on removing the ash content and volatile content in the polyolefin elastomer and can be promoted industrially.

[0081] The specific embodiments described above have further elaborated on the purpose, technical solutions, and beneficial effects of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not used to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for preparing a polyolefin elastomer, characterized in that, The preparation method includes: Under anhydrous and anaerobic conditions, one or more olefin monomers, a main catalyst, and a cocatalyst are stirred in an organic solvent for a polymerization reaction to obtain a glue solution containing a polyolefin elastomer; The glue solution is subjected to ash removal and devolatilization through an n-stage screw and then extruded and granulated to prepare a polyolefin elastomer; wherein, n = 3 or n = 4; In the case of n = 3, water is used as a reagent in the first-stage screw, water is used as a reagent in the second-stage screw, and extrusion granulation is carried out in the third-stage screw; or, an aqueous acid solution is used as a reagent in the first-stage screw, an aqueous alkali solution is used as a reagent in the second-stage screw, and extrusion granulation is carried out in the third-stage screw; or, an aqueous alkali solution is used as a reagent in the first-stage screw, an aqueous acid solution is used as a reagent in the second-stage screw, and extrusion granulation is carried out in the third-stage screw; In the case of n = 4, an aqueous acid solution is used as a reagent in the first-stage screw, water is used as a reagent in the second-stage screw, an aqueous alkali solution is used as a reagent in the third-stage screw, and extrusion granulation is carried out in the fourth-stage screw; or, an aqueous alkali solution is used as a reagent in the first-stage screw, water is used as a reagent in the second-stage screw, an aqueous acid solution is used as a reagent in the third-stage screw, and extrusion granulation is carried out in the fourth-stage screw; or, water is used as a reagent in the first-stage screw to the third-stage screw, and extrusion granulation is carried out in the fourth-stage screw; The rotation speed of the first-stage screw is 10 - 30 rpm, and the temperature is 20 - 40 °C; the rotation speed of the n-stage screw is 110 - 130 rpm, and the temperature is 180 - 200 °C; The rotation speeds of the other screws between the first-stage screw and the n-stage screw are 40 - 60 rpm respectively, and the temperatures are 20 - 40 °C respectively.

2. The preparation method according to claim 1, characterized in that, A twin-screw is used in each stage of the n-stage screw, and an inert gas delivery unit for injecting an inert gas into the screw and a degassing unit for removing gas from the glue solution are configured.

3. The preparation method according to claim 1, wherein The mass fraction of the aqueous acid solution and / or the aqueous alkali solution is 0.1 - 10% respectively; The volume of the aqueous acid solution and / or the aqueous alkali solution is 0.01 - 1% of the organic solvent in the glue solution; The volume of water is 10 - 100% of the organic solvent in the glue solution.

4. The preparation method according to claim 1, characterized in that, The organic solvent includes at least one of isobutane, n-pentane, isopentane, n-hexane, methylcyclopentane, n-heptane, methylcyclohexane, isooctane, toluene; The olefin monomers include ethylene and C3-C 20 α-olefins; 20 ​ The main catalyst includes at least one of a metallocene catalyst and an α-diimine nickel catalyst; The cocatalyst includes at least one of triethylaluminum, triisobutylaluminum, trihexylaluminum, trioctylaluminum, diethylaluminum chloride, dichloroethylaluminum, methylaluminoxane, modified methylaluminoxane, perfluorophenylboron, triphenylcarbenium tetrakis(pentafluorophenyl)borate, N,N-dimethylanilinium tetrakis(pentafluorophenyl)borate, N,N-di(hexadecyl)anilinium tetrakis(pentafluorophenyl)borate.

5. The preparation method according to claim 4, characterized in that, The temperature of the polymerization reaction is 60 - 200 °C, the pressure is 1 - 10 MPa, and the time is 5 - 60 min; C3 to C 20 The α-olefins include at least one of propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-decene, 1-dodecene, 1-hexadecene, 1-octadecene, and 1-eicosene.

6. The preparation method according to claim 1, wherein The ash content of the polyolefin elastomer is ≤ 50 ppm, and the volatile content is ≤ 50 ppm.

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