Uv-resistant thermoplastic polyolefin elastomer and method for its production

Abstract

The application provides a preparation method of a thermoplastic polyolefin elastomer resistant to ultraviolet aging, comprising the following steps: a) mixing ethylene, an alpha-olefin, an organic solvent, a main catalyst and a cocatalyst after refining, and an ultraviolet absorber, and performing a polymerization reaction to obtain a reaction material; and b) after flash evaporation of the reaction material obtained in the step a), the reaction material is added into a double-screw extruder for multistage devolatilization, and a thermoplastic polyolefin elastomer resistant to ultraviolet aging is obtained after discharging. The preparation method adds an anti-ultraviolet aging agent in the production process of the POE, and does not need to add the anti-ultraviolet aging agent in the process of manufacturing the photovoltaic adhesive film, thereby fundamentally solving the problem that the anti-ultraviolet absorber cannot be uniformly dispersed in the POE in the process of manufacturing the photovoltaic adhesive film, and the photovoltaic adhesive film has insufficient anti-ultraviolet aging performance. Moreover, the thermoplastic polyolefin elastomer prepared by the preparation method has greatly improved mechanical properties after aging, a small change in a yellow index, and stable ultraviolet aging resistance.

Description

Technical Field

[0001] This invention relates to the field of polyolefin materials technology, and more specifically, to a thermoplastic polyolefin elastomer resistant to ultraviolet aging and its preparation method. Background Technology

[0002] Thermoplastic polyolefin elastomer, abbreviated as "POE". Recently, my country has an urgent need for more clean energy sources such as solar power, leading to a surge in demand for POE used in photovoltaic films. According to survey results, in 2021, my country used approximately 120,000 tons of POE for photovoltaic films, accounting for 21% of the country's total POE consumption, a very large amount.

[0003] Typically, photovoltaic (PV) films consist of over 95% polyether oxide (POE) and less than 5% additives (including UV absorbers). However, PV films produced using this traditional method still do not have ideal UV aging resistance. This is because the UV absorbers cannot be uniformly dispersed within the POE during the PV film manufacturing process. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to provide a UV-resistant thermoplastic polyolefin elastomer and its preparation method. The preparation method provided by the present invention adds an anti-UV aging agent during the production process of POE, which fundamentally solves the problem that the UV absorber cannot be uniformly dispersed in POE during the photovoltaic film manufacturing process.

[0005] This invention provides a method for preparing a UV-resistant thermoplastic polyolefin elastomer, comprising the following steps:

[0006] a) After refining ethylene, α-olefin, organic solvent, main catalyst, and co-catalyst, they are mixed with ultraviolet absorber to carry out a polymerization reaction to obtain the reaction material;

[0007] b) After flash evaporation of the reactants obtained in step a), the reactants are fed into a twin-screw extruder for multi-stage devolatilization, and the discharged material is a thermoplastic polyolefin elastomer resistant to UV aging.

[0008] Preferably, the α-olefin in step a) is selected from one or more 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.

[0009] The organic solvent is selected from n-hexane, n-butane, isobutane, cyclobutane, n-pentane, or isopentane;

[0010] The main catalyst is selected from diphenylcarbamate-cyclopentadienyl-stilbene zirconium dichloride, diphenylcarbamate-cyclopentadienyl-(2-dimethylamino-stilbene)zirconium dichloride, bis[2-(3',5'-di-tert-butylphenyl)-indenyl]zirconium dichloride, biscyclopentadienyl-bisphenoxyzirconium, vinyl-bisindenyl-bisphenoxyzirconium, bis(salicylyl-benzimino)titanium dichloride, [N-(3,5-di-tert-butylsalicylyl...] [2-Diphenylphosphinobenzylamine] Titanium trichloride, dimethylsilylbridged bisindenylzirconium dichloride, dimethylsilylbridged tetramethylcyclopentadienyl-tert-butylamino-dimethyltitanium, dimethylsilylbridged 3-pyrrolidinyl-tert-butylamino-dimethyltitanium, pentamethylcyclopentadienyl-(2-phenylphenoxy)-titanium dichloride, pentamethylcyclopentadienyl-(2,6-diisopropylphenoxy)-titanium dichloride;

[0011] The cocatalyst is selected from one or more of the following: methylaluminoxane compounds, modified methylaluminoxane compounds, tris(pentafluorophenyl)boron compounds, triphenylcarbium tetra(pentafluorophenyl)boron compounds, N,N-dimethylaniline tetra(pentafluorophenyl)boron compounds, triisobutylaluminum, and trimethylaluminum.

[0012] Preferably, the molar ratio of ethylene to α-olefin in step a) is (1-4):1;

[0013] The molar ratio of the co-catalyst to the main catalyst is (3-10000):1;

[0014] The volume ratio of the organic solvent to the two monomer raw materials, ethylene and α-olefin, is (0.5-5):1;

[0015] The molar concentration of the main catalyst in the organic solvent is 0.5 μmol / L to 1.5 μmol / L.

[0016] Preferably, the refining process in step a) involves multiple cycles of refining using a raw material refining system; during the refining process, a refining agent is added to remove impurities such as sulfur, chlorine, carbon monoxide, water, acetylene, methanol, oxygen, and methane, resulting in impurities ≤1ppm after refining.

[0017] Preferably, the ultraviolet absorber in step a) is one or more of benzophenone ultraviolet absorbers, benzotriazole ultraviolet absorbers, triazine ultraviolet absorbers, and salicylate ultraviolet absorbers;

[0018] The molar concentration of the ultraviolet absorber in the organic solvent is 1‰mol / L to 10‰mol / L.

[0019] Preferably, the polymerization reaction in step a) is carried out in a reactor; the temperature of the polymerization reaction is 120℃~180℃, the pressure is 1MPa~5MPa, and the time is 5min~30min.

[0020] Preferably, the flash evaporation process in step b) is carried out in a flash evaporator; the pressure inside the flash evaporator is 0.1 MPa to 5 MPa, the pressure difference between the inside and outside of the flash evaporator is 1 MPa to 10 MPa, the temperature is 120℃ to 200℃, and the time is 3 min to 30 min.

[0021] Preferably, the multi-stage devolatilization in step b) is 2 to 5 stages of devolatilization.

[0022] Preferably, the conditions and parameters for each stage of devolatilization are as follows:

[0023] The screw has 5 to 15 cylinder steps, 4 to 7 vacuum ports, a vacuum pressure of -0.3 MPa to 0.01 MPa, a temperature of 150℃ to 250℃ for each cylinder, a rotation speed of 50 rpm to 200 rpm, a polymer flow rate of 10 kg / h to 200 kg / h in the screw, and a residence time of 3 min to 30 min.

[0024] This invention provides a thermoplastic polyolefin elastomer resistant to ultraviolet aging, which is prepared by the preparation method described in the above technical solution.

[0025] This invention provides a UV-resistant thermoplastic polyolefin elastomer and its preparation method. The preparation method includes the following steps: a) refining ethylene, α-olefin, organic solvent, main catalyst, and co-catalyst, then mixing them with a UV absorber to carry out a polymerization reaction to obtain the reactants; b) flash evaporating the reactants obtained in step a), then adding them to a twin-screw extruder for multi-stage devolatilization, and discharging the UV-resistant thermoplastic polyolefin elastomer. Compared with the prior art, the preparation method provided by this invention uses specific process steps to achieve better overall interaction. The UV aging agent is added during the production of POE, eliminating the need to add it during the photovoltaic film manufacturing process. This fundamentally solves the problem of insufficient UV aging resistance of photovoltaic films due to the inability of the UV absorber to be uniformly dispersed in POE during photovoltaic film manufacturing. Furthermore, the thermoplastic polyolefin elastomer prepared using the method provided by this invention exhibits significantly improved mechanical properties after aging. Simultaneously, after UV aging, the yellow index changes little, indicating relatively stable UV aging resistance, and the mechanical properties after UV aging are significantly improved compared to the control group.

[0026] In addition, the preparation method provided by this invention is simple, mild and easy to control, and has broad application prospects. Detailed Implementation

[0027] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0028] This invention provides a method for preparing a UV-resistant thermoplastic polyolefin elastomer, comprising the following steps:

[0029] a) After refining ethylene, α-olefin, organic solvent, main catalyst, and co-catalyst, they are mixed with ultraviolet absorber to carry out a polymerization reaction to obtain the reaction material;

[0030] b) After flash evaporation of the reactants obtained in step a), the reactants are fed into a twin-screw extruder for multi-stage devolatilization, and the discharged material is a thermoplastic polyolefin elastomer resistant to UV aging.

[0031] The present invention first purifies ethylene, α-olefin, organic solvent, main catalyst and co-catalyst, and then mixes them with ultraviolet absorber to carry out polymerization reaction to obtain reaction materials.

[0032] In this invention, the ethylene and α-olefin are monomer raw materials; the α-olefin is preferably selected from one or more 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, more preferably 1-octene; this invention does not have any special restrictions on the source of the ethylene and α-olefin, and commercially available products or homemade products well known to those skilled in the art can be used.

[0033] In this invention, the molar ratio of ethylene to α-olefin is preferably (1-4):1, more preferably (1-2):1.

[0034] In this invention, the organic solvent is preferably selected from n-hexane, n-butane, isobutane, cyclobutane, n-pentane, or isopentane, and more preferably n-hexane. This invention does not impose any particular limitation on the source of the organic solvent; commercially available products well-known to those skilled in the art can be used.

[0035] In this invention, the volume ratio of the organic solvent to the two monomer raw materials, ethylene and α-olefin, is preferably (0.5-5):1, and more preferably (1-3):1.

[0036] In this invention, the main catalyst is preferably selected from diphenylcarbamate-cyclopentadienyl-wildyl zirconium dichloride, diphenylcarbamate-cyclopentadienyl-(2-dimethylamino-wildyl)zirconium dichloride, bis[2-(3',5'-di-tert-butylphenyl)-indenyl]zirconium dichloride, biscyclopentadienyl-bisphenoxyzirconium, vinyl-bisindenyl-bisphenoxyzirconium, bis(salicylyl-benzyl)titanium dichloride, [N-(3,5-di-tert-butylsalicylyl)-2-diphenylphosphinobenzyl]titanium trichloride, dimethyl... The catalyst is selected from one or more of the following: dimethylsilylbridged bis(indenyl)zirconia, dimethylsilylbridged tetramethylcyclopentadienyl-tert-butylamino-dimethyltitanium, dimethylsilylbridged 3-pyrrolidinyl-tert-butylamino-dimethyltitanium, pentamethylcyclopentadienyl-(2-phenylphenoxy)-titanium chloride, and pentamethylcyclopentadienyl-(2,6-diisopropylphenoxy)-titanium chloride, more preferably diphenylcarbamatyl-cyclopentadienyl-ziron dichloride or pentamethylcyclopentadienyl-(2-phenylphenoxy)-titanium chloride. The present invention does not impose any particular limitation on the source of the main catalyst; commercially available single-active-center metallocene catalysts or post-metallocene catalysts well known to those skilled in the art can be used.

[0037] In this invention, the molar concentration of the main catalyst in the organic solvent is preferably 0.5 μmol / L to 1.5 μmol / L, more preferably 0.8 μmol / L to 1.2 μmol / L, and most preferably 1 μmol / L.

[0038] In this invention, the co-catalyst is preferably selected from one or more of methylaluminoxane compounds, modified methylaluminoxane compounds, tris(pentafluorophenyl)boron compounds, triphenylcarbium tetra(pentafluorophenyl)boron compounds, N,N-dimethylaniline tetra(pentafluorophenyl)boron compounds, triisobutylaluminum, and trimethylaluminum, more preferably methylaluminoxane compounds or tris(pentafluorophenyl)boron compounds. This invention does not impose any special restrictions on the source of the co-catalyst; commercially available products well known to those skilled in the art can be used.

[0039] In this invention, the molar ratio of the co-catalyst to the main catalyst is preferably (3-10000):1, more preferably (10-8000):1, even more preferably (20-6000):1, even more preferably (50-4000):1, and even more preferably (100-3000):1.

[0040] In this invention, the refining process preferably employs a raw material refining system for multiple cyclic refining cycles. During the refining process, a refining agent is preferably added to remove impurities such as sulfur, chlorine, carbon monoxide, water, acetylene, methanol, oxygen, and methane, resulting in impurities ≤1 ppm after refining. This invention does not impose any special restrictions on the type of refining agent. Based on the above refining requirements, dechlorination adsorbents, deoxygenation adsorbents, dehydration adsorbents, desulfurization adsorbents, CO removal adsorbents, acetylene removal adsorbents, methane removal adsorbents, and methanol removal adsorbents well-known to those skilled in the art are selected. Simultaneously, to ensure optimal adsorption performance, the bulk density of the adsorbent is preferably 0.5 kg / L to 1.0 kg / L.

[0041] In this invention, the ultraviolet absorber is preferably one or more of benzophenone-based ultraviolet absorbers, benzotriazole-based ultraviolet absorbers, triazine-based ultraviolet absorbers, and salicylate-based ultraviolet absorbers, more preferably benzotriazole-based or triazine-based ultraviolet absorbers. This invention does not impose any special restrictions on the source of the ultraviolet absorber; commercially available products well-known to those skilled in the art can be used.

[0042] In this invention, the molar concentration of the ultraviolet absorber in the organic solvent is preferably 1‰mol / L to 10‰mol / L, more preferably 3‰mol / L to 5‰mol / L.

[0043] In this invention, the polymerization reaction is preferably carried out in a reactor; the temperature of the polymerization reaction is preferably 120°C to 180°C, more preferably 140°C to 150°C, the pressure is preferably 1MPa to 5MPa, more preferably 4MPa to 4.5MPa, and the time is preferably 5min to 30min, more preferably 10min to 15min.

[0044] After obtaining the reactants, the present invention flash-evaporates the reactants and then feeds them into a twin-screw extruder for multi-stage devolatilization, and discharges the material to obtain a thermoplastic polyolefin elastomer resistant to ultraviolet aging.

[0045] In this invention, the flash evaporation process is preferably carried out in a flash evaporator; the flash evaporator can be a drop-strip flash evaporator, a flash evaporator with double helical stirring blades, or a flash evaporator with single helical stirring blades; among which, the flash evaporator with double helical stirring blades is preferred, as it provides more uniform stirring and evaporates more water compared to the single helical type.

[0046] In this invention, the pressure inside the flash evaporator is preferably 0.1 MPa to 5 MPa, more preferably 0.5 MPa to 3 MPa; the pressure difference between the inside and outside of the evaporator is preferably 1 MPa to 10 MPa, more preferably 3 MPa to 10 MPa; the temperature is preferably 120℃ to 200℃, more preferably 120℃ to 150℃; the time (i.e., the material residence time) is preferably 3 min to 30 min, more preferably 10 min to 20 min; based on these conditions, most of the volatile matter is removed.

[0047] In this invention, the multi-stage devolatilization is preferably 2 to 5 stages, more preferably 3 stages; it is implemented using a multi-stage devolatilization device well known to those skilled in the art. This invention controls the devolatilization process through screw extrusion: the multi-stage devolatilization device has a higher devolatilization efficiency than single-stage devolatilization, resulting in more thorough removal of small molecules and significantly reducing the content of small molecules in the product.

[0048] In this invention, the conditions and parameters for each stage of devolatilization are as follows:

[0049] The screw upper cylinder has a preferred number of stages of 5 to 15, more preferably 7 to 12; a preferred number of vacuum ports of 4 to 7, more preferably 4 to 6; a preferred vacuum pressure of -0.3 MPa to 0.01 MPa, more preferably -0.2 MPa to 0.01 MPa; a preferred temperature of 150℃ to 250℃, more preferably 160℃ to 200℃; a preferred rotational speed of 50 rpm to 200 rpm, more preferably 60 rpm to 100 rpm; a preferred flow rate of polymer in the screw of 10 kg / h to 200 kg / h, more preferably 40 kg / h to 100 kg / h; and a preferred residence time of 3 min to 30 min, more preferably 5 min to 15 min.

[0050] The preparation method provided by this invention is simple, mild, and easy to control, and has broad application prospects.

[0051] This invention provides a thermoplastic polyolefin elastomer resistant to ultraviolet aging, which is prepared by the preparation method described in the above technical solution.

[0052] In this invention, UV aging resistance can be characterized by the yellow index after aging in a UV aging chamber. The POE yellow index obtained by this method has a difference of less than 1 before and after aging.

[0053] The preparation method provided by this invention employs specific process steps to achieve better overall interaction. By adding an anti-UV aging agent during the production of POE, it eliminates the need to add an anti-UV aging agent during the photovoltaic film manufacturing process. This fundamentally solves the problem of insufficient UV aging resistance of photovoltaic films due to the inability of the anti-UV absorber to be uniformly dispersed in POE during photovoltaic film manufacturing. Furthermore, the thermoplastic polyolefin elastomer prepared using the method provided by this invention exhibits significantly improved mechanical properties after aging. Simultaneously, the yellow index changes little after UV aging, indicating relatively stable UV aging resistance, and the mechanical properties after UV aging show a significant improvement compared to the control group.

[0054] This invention provides a UV-resistant thermoplastic polyolefin elastomer and its preparation method. The preparation method includes the following steps: a) refining ethylene, α-olefin, organic solvent, main catalyst, and co-catalyst, then mixing them with a UV absorber to carry out a polymerization reaction to obtain the reactants; b) flash evaporating the reactants obtained in step a), then adding them to a twin-screw extruder for multi-stage devolatilization, and discharging the UV-resistant thermoplastic polyolefin elastomer. Compared with the prior art, the preparation method provided by this invention uses specific process steps to achieve better overall interaction. The UV aging agent is added during the production of POE, eliminating the need to add it during the photovoltaic film manufacturing process. This fundamentally solves the problem of insufficient UV aging resistance of photovoltaic films due to the inability of the UV absorber to be uniformly dispersed in POE during photovoltaic film manufacturing. Furthermore, the thermoplastic polyolefin elastomer prepared using the method provided by this invention exhibits significantly improved mechanical properties after aging. Simultaneously, after UV aging, the yellow index changes little, indicating relatively stable UV aging resistance, and the mechanical properties after UV aging are significantly improved compared to the control group.

[0055] In addition, the preparation method provided by this invention is simple, mild and easy to control, and has broad application prospects.

[0056] To further illustrate the present invention, the following embodiments will be described in detail.

[0057] Example 1

[0058] A method for preparing a green thermoplastic polyolefin elastomer (POE) mainly includes the following steps:

[0059] (1) Raw materials: 1-octene and ethylene (molar ratio of 1-octene to ethylene is 1:2, total amount of ethylene and octene is 200kg), metallocene catalyst diphenylcarbamate-cyclopentadienyl-zirconium dichloride (molar concentration in solvent is 1μmol / L), co-catalyst methylaluminoxane compound (molar ratio of co-catalyst to main catalyst is 100:1), solvent n-hexane (molar ratio of solvent to (total amount of ethylene and 1-octene) is 1mL:1mL), refining agent is dechlorination adsorbent, deoxygenation adsorbent, dehydration adsorbent, desulfurization adsorbent, CO removal adsorbent, acetylene removal adsorbent, methane removal adsorbent, methanol removal adsorbent, total impurities such as chlorine, water, oxygen, sulfur, CO, acetylene, methanol and methane in the refined material are ≤1ppm; the concentration of benzotriazole ultraviolet absorber UV328 is 5‰mol / L.

[0060] After reacting for 15 minutes in a reactor at 150℃ and 4.5MPa, the material flows out at a flow rate of 200kg / h and enters a flash evaporator.

[0061] (2) Flash evaporation process: control the pressure inside the vessel to 3MPa, control the pressure difference to 10MPa, and flash evaporate at 140℃ for 10min.

[0062] (3) Twin-screw extrusion control: A three-stage devolatilization device is selected. The first-stage screw has 7 barrel stages and 4 vacuum ports. The vacuum pressure is -0.2MPa. The temperature of each barrel is controlled at 180℃ and the rotation speed is controlled at 60rpm. The flow rate of polymer in the screw is controlled at 40kg / h and the polymer material stays for 5min. The second-stage screw has a vacuum port in the 5th barrel. The other parts are the same as the first-stage screw. The green pigment is added at the 2nd barrel of the second-stage screw. After a residence time of 5min, it enters the third-stage screw. The third-stage screw has the same structure as the first-stage screw. All materials stay for 5min and the discharged material is a thermoplastic polyolefin elastomer resistant to UV aging.

[0063] Example 2

[0064] A method for preparing a green thermoplastic polyolefin elastomer (POE) mainly includes the following steps:

[0065] (1) Raw materials: 1-octene and ethylene (molar ratio of 1-octene to ethylene is 1:1, total amount of ethylene and octene is 200kg), metallocene catalyst pentamethylcyclopentadienyl-(2-phenylphenoxy)-titanium dichloride (molar concentration in solvent is 1μmol / L), co-catalyst tris(pentafluorophenyl)boron compound (molar ratio of co-catalyst to main catalyst is 100:1), solvent n-hexane (molar ratio of solvent to (total amount of ethylene and 1-octene) is 1mL:1mL), refining agent is dechlorination adsorbent, deoxygenation adsorbent, dehydration adsorbent, desulfurization adsorbent, CO removal adsorbent, acetylene removal adsorbent, methane removal adsorbent, methanol removal adsorbent, the total value of impurities such as chlorine, water, oxygen, sulfur, CO, acetylene, methanol and methane in the refined material is ≤1ppm; the concentration of benzotriazole ultraviolet absorber UV328 is 3‰mol / L.

[0066] After reacting for 10 minutes in a reactor at 140℃ and 4MPa, the material flows out at a flow rate of 200kg / h and enters a flash reactor.

[0067] (2) Flash evaporation process: control the pressure inside the vessel to 3MPa, control the pressure difference to 10MPa, and flash evaporate at 140℃ for 10min.

[0068] (3) Twin-screw extrusion control: A three-stage devolatilization device is selected. The first-stage screw has 7 barrel stages and 4 vacuum ports. The vacuum pressure is -0.2MPa. The temperature of each barrel is controlled at 180℃ and the rotation speed is controlled at 60rpm. The flow rate of polymer in the screw is controlled at 40kg / h and the polymer material stays for 10min. The second-stage screw has a vacuum port in the 5th barrel. Other parameters and process settings are the same as the first-stage screw. The third-stage screw has a vacuum port in the 6th barrel. Other parameters and process settings are the same as the first-stage screw. The polymer flows through the first-stage screw, the second-stage screw, and the third-stage screw in sequence. The discharged material is a thermoplastic polyolefin elastomer resistant to ultraviolet aging.

[0069] Example 3

[0070] A method for preparing a green thermoplastic polyolefin elastomer (POE) mainly includes the following steps:

[0071] (1) Raw materials: 1-octene and ethylene (molar ratio of 1-octene to ethylene is 1:1, total amount of ethylene and octene is 200kg), metallocene catalyst pentamethylcyclopentadienyl-(2-phenylphenoxy)-titanium dichloride (molar concentration in solvent is 1μmol / L), co-catalyst tris(pentafluorophenyl)boron compound (molar ratio of co-catalyst to main catalyst is 100:1), solvent n-hexane (molar ratio of solvent to (total amount of ethylene and 1-octene) is 1mL:1mL), refining agent is dechlorination adsorbent, deoxygenation adsorbent, dehydration adsorbent, desulfurization adsorbent, CO removal adsorbent, acetylene removal adsorbent, methane removal adsorbent, methanol removal adsorbent, total impurities such as chlorine, water, oxygen, sulfur, CO, acetylene, methanol and methane in the refined material are ≤1ppm; the concentration of triazine ultraviolet absorber Tinuvin 1577 is 3‰mol / L.

[0072] After reacting for 10 minutes in a reactor at 140℃ and 4MPa, the material flows out at a flow rate of 200kg / h and enters a flash reactor.

[0073] (2) Flash evaporation process: control the pressure inside the vessel to 3MPa, control the pressure difference to 10MPa, and flash evaporate at 140℃ for 10min.

[0074] (3) Twin-screw extrusion control: A three-stage devolatilization device is selected. The first-stage screw has 7 barrel stages and 4 vacuum ports. The vacuum pressure is -0.2MPa. The temperature of each barrel is controlled at 180℃ and the rotation speed is controlled at 60rpm. The flow rate of polymer in the screw is controlled at 40kg / h and the polymer material stays for 10min. The second-stage screw has a vacuum port in the 5th barrel. Other parameters and process settings are the same as the first-stage screw. The third-stage screw has a vacuum port in the 6th barrel. Other parameters and process settings are the same as the first-stage screw. The polymer flows through the first-stage screw, the second-stage screw, and the third-stage screw in sequence. The discharged material is a thermoplastic polyolefin elastomer resistant to ultraviolet aging.

[0075] Example 4

[0076] A method for preparing a green thermoplastic polyolefin elastomer (POE) mainly includes the following steps:

[0077] (1) Raw materials: 1-octene and ethylene (molar ratio of 1-octene to ethylene is 1:1, total amount of ethylene and octene is 200kg), metallocene catalyst pentamethylcyclopentadienyl-(2-phenylphenoxy)-titanium dichloride (molar concentration in solvent is 1μmol / L), co-catalyst tris(pentafluorophenyl)boron compound (molar ratio of co-catalyst to main catalyst is 100:1), solvent n-hexane (molar ratio of solvent to (total amount of ethylene and 1-octene) is 1mL:1mL), refining agent is dechlorination adsorbent, deoxygenation adsorbent, dehydration adsorbent, desulfurization adsorbent, CO removal adsorbent, acetylene removal adsorbent, methane removal adsorbent, methanol removal adsorbent, the total value of impurities such as chlorine, water, oxygen, sulfur, CO, acetylene, methanol and methane in the refined material is ≤1ppm; the concentration of benzophenone-based ultraviolet absorber JADEWIN BP-6 is 3‰mol / L.

[0078] After reacting for 10 minutes in a reactor at 140℃ and 4MPa, the material flows out at a flow rate of 200kg / h and enters a flash reactor.

[0079] (2) Flash evaporation process: control the pressure inside the vessel to 3MPa, control the pressure difference to 10MPa, and flash evaporate at 140℃ for 10min.

[0080] (3) Twin-screw extrusion control: A three-stage devolatilization device is selected. The first-stage screw has 7 barrel stages and 4 vacuum ports. The vacuum pressure is -0.2MPa. The temperature of each barrel is controlled at 180℃ and the rotation speed is controlled at 60rpm. The flow rate of polymer in the screw is controlled at 40kg / h and the polymer material stays for 10min. The second-stage screw has a vacuum port in the 5th barrel. Other parameters and process settings are the same as the first-stage screw. The third-stage screw has a vacuum port in the 6th barrel. Other parameters and process settings are the same as the first-stage screw. The polymer flows through the first-stage screw, the second-stage screw, and the third-stage screw in sequence. The discharged material is a thermoplastic polyolefin elastomer resistant to ultraviolet aging.

[0081] Example 5

[0082] A method for preparing a green thermoplastic polyolefin elastomer (POE) mainly includes the following steps:

[0083] (1) Raw materials: 1-octene and ethylene (molar ratio of 1-octene to ethylene is 1:1, total amount of ethylene and octene is 200kg), metallocene catalyst pentamethylcyclopentadienyl-(2-phenylphenoxy)-titanium dichloride (molar concentration in solvent is 1μmol / L), co-catalyst tris(pentafluorophenyl)boron compound (molar ratio of co-catalyst to main catalyst is 100:1), solvent n-hexane (molar ratio of solvent to (total amount of ethylene and 1-octene) is 1mL:1mL), refining agent is dechlorination adsorbent, deoxygenation adsorbent, dehydration adsorbent, desulfurization adsorbent, CO removal adsorbent, acetylene removal adsorbent, methane removal adsorbent, methanol removal adsorbent, total impurities such as chlorine, water, oxygen, sulfur, CO, acetylene, methanol and methane in the refined material are ≤1ppm; the concentration of salicylate phenyl salicylate (manufacturer: Huijinchuan) is 3‰mol / L.

[0084] After reacting for 10 minutes in a reactor at 140℃ and 4MPa, the material flows out at a flow rate of 200kg / h and enters a flash reactor.

[0085] (2) Flash evaporation process: control the pressure inside the vessel to 3MPa, control the pressure difference to 10MPa, and flash evaporate at 140℃ for 10min.

[0086] (3) Twin-screw extrusion control: A three-stage devolatilization device is selected. The first-stage screw has 7 barrel stages and 4 vacuum ports. The vacuum pressure is -0.2MPa. The temperature of each barrel is controlled at 180℃ and the rotation speed is controlled at 60rpm. The flow rate of polymer in the screw is controlled at 40kg / h and the polymer material stays for 10min. The second-stage screw has a vacuum port in the 5th barrel. Other parameters and process settings are the same as the first-stage screw. The third-stage screw has a vacuum port in the 6th barrel. Other parameters and process settings are the same as the first-stage screw. The polymer flows through the first-stage screw, the second-stage screw, and the third-stage screw in sequence. The discharged material is a thermoplastic polyolefin elastomer resistant to ultraviolet aging.

[0087] Comparative Example 1

[0088] Except for the omission of the benzotriazole UV absorber UV328, all other steps, conditions, and parameters are the same as in Example 1.

[0089] Comparative Example 2

[0090] Except for the omission of the benzotriazole UV absorber UV328, all other steps, conditions, and parameters are the same as in Example 2.

[0091] Comparative Example 3

[0092] Except for the omission of the triazine UV absorber Tinuvin 1577, all other steps, conditions, and parameters were the same as in Example 3.

[0093] Comparative Example 4

[0094] Except for the absence of the benzophenone-based ultraviolet absorber JADEWIN BP-6, all other steps, conditions, and parameters are the same as in Example 4.

[0095] Comparative Example 5

[0096] Except for the omission of the salicylate-based UV absorber phenyl salicylate (manufacturer: Huijinchuan), all other steps, conditions, and parameters are the same as in Example 5.

[0097] The yellow index of the samples in the examples and comparative examples was tested and recorded as Y1. Then, they were placed in a UV aging chamber at a constant temperature of 60℃±5℃ for one week of UV aging. After the time was up, they were restored in an open environment at 23℃±5℃ and relative humidity less than 75% for 2 to 4 hours. The yellow index was then tested and recorded as Y2. The test results are shown in Table 1 below.

[0098] Table 1. Yellow Index Test Results for Examples and Comparative Examples (Yellow Index Test Method: HG / T3862-2006)

[0099]

[0100]

[0101] The aged products with the yellow index tested above were subjected to mechanical property and density tests according to GB / T 1040.3-2006 and GB / T 1033.1-2008 respectively, and the results are shown in Table 2.

[0102] Table 2 Other performance characteristics of the examples and comparative examples

[0103] <![CDATA[Density / g / cm 3 > Tensile strength / MPa Elongation at break / % Example 1 0.889 6.2 910 Comparative Example 1 0.890 5.1 800 Example 2 0.888 6.3 900 Comparative Example 2 0.889 6.2 810 Example 3 0.889 6.4 910 Comparative Example 3 0.889 5.2 800 Example 4 0.890 6.5 910 Comparative Example 4 0.889 5.3 810 Example 5 0.887 6.4 900 Comparative Example 5 0.888 5.2 800

[0104] In terms of UV aging resistance:

[0105] △Y = Y2 - Y1 represents the degree of excellence in UV aging resistance; the smaller the value, the better the aging resistance.

[0106] Comparing Examples 1 and 2 with Comparative Examples 1 and 2, we can conclude that:

[0107] In the POE production process, under different processes, adding a UV absorber during polymerization can improve aging resistance compared to not adding a UV absorber.

[0108] Comparing Examples 2-5 with Comparative Examples 2-5, we can conclude that:

[0109] In terms of UV aging resistance, benzotriazole and triazine UV absorbers are the most effective, followed by benzophenone and salicylates.

[0110] From the perspective of mechanical properties:

[0111] The POE produced using the preparation method provided by this invention exhibits significantly improved mechanical properties after aging.

[0112] In summary, the POE produced by the preparation method provided by this invention shows a small change in yellow index after UV aging, indicating relatively stable UV aging resistance. At the same time, the mechanical properties after UV aging are significantly improved compared to the control group.

[0113] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing a UV-resistant thermoplastic polyolefin elastomer, comprising the following steps: a) Ethylene, α-olefin, organic solvent, main catalyst, and co-catalyst are purified and then mixed with a UV absorber to carry out a polymerization reaction to obtain the reaction material; the UV absorber is a benzotriazole UV absorber or a triazine UV absorber. The main catalyst is a single-active-center metallocene catalyst or a single-active-center post-metallocene catalyst. The molar concentration of the ultraviolet absorber in the organic solvent is 3‰mol / L~5‰mol / L; b) After flash evaporation of the reactants obtained in step a), the reactants are fed into a twin-screw extruder for multi-stage devolatilization, and the discharged material is a thermoplastic polyolefin elastomer resistant to UV aging.

2. The preparation method according to claim 1, characterized in that, The α-olefin mentioned in step a) is selected from one or more 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. The organic solvent is selected from n-hexane, n-butane, isobutane, cyclobutane, n-pentane, or isopentane; The main catalyst is selected from diphenylcarbamate-cyclopentadienyl-stilbene zirconium dichloride, diphenylcarbamate-cyclopentadienyl-(2-dimethylamino-stilbene)zirconium dichloride, bis[2-(3',5'-di-tert-butylphenyl)-indenyl]zirconium dichloride, biscyclopentadienyl-bisphenoxyzirconium, vinyl-bisindenyl-bisphenoxyzirconium, bis(salicylyl-benzimino)titanium dichloride, [N-(3,5-di-tert-butylsalicylyl...] [2-Diphenylphosphinobenzylamine] Titanium trichloride, dimethylsilylbridged bisindenylzirconium dichloride, dimethylsilylbridged tetramethylcyclopentadienyl-tert-butylamino-dimethyltitanium, dimethylsilylbridged 3-pyrrolidinyl-tert-butylamino-dimethyltitanium, pentamethylcyclopentadienyl-(2-phenylphenoxy)-titanium dichloride, pentamethylcyclopentadienyl-(2,6-diisopropylphenoxy)-titanium dichloride; The cocatalyst is selected from one or more of the following: methylaluminoxane compounds, modified methylaluminoxane compounds, tris(pentafluorophenyl)boron compounds, triphenylcarbium tetra(pentafluorophenyl)boron compounds, N,N-dimethylaniline tetra(pentafluorophenyl)boron compounds, triisobutylaluminum, and trimethylaluminum.

3. The preparation method according to claim 1, characterized in that, The molar ratio of ethylene to α-olefin in step a) is (1~4):1; The molar ratio of the co-catalyst to the main catalyst is (3~10000):1; The volume ratio of the organic solvent to the two monomer raw materials, ethylene and α-olefin, is (0.5~5):1; The molar concentration of the main catalyst in the organic solvent is 0.5 μmol / L to 1.5 μmol / L.

4. The preparation method according to claim 1, characterized in that, The refining process described in step a) involves multiple cycles of refining using a raw material refining system. During the refining process, a refining agent is added to remove impurities such as sulfur, chlorine, carbon monoxide, water, acetylene, methanol, oxygen, and methane. After refining, the impurities are ≤1ppm.

5. The preparation method according to claim 1, characterized in that, The polymerization reaction described in step a) is carried out in a reactor; the temperature of the polymerization reaction is 120℃~180℃, the pressure is 1MPa~5MPa, and the time is 5min~30min.

6. The preparation method according to claim 1, characterized in that, The flash evaporation process described in step b) is carried out in a flash evaporator; the pressure inside the flash evaporator is 0.1MPa~5MPa, the pressure difference between the inside and outside of the flash evaporator is 1MPa~10MPa, the temperature is 120℃~200℃, and the time is 3min~30min.

7. The preparation method according to claim 1, characterized in that, The multi-stage devolatilization mentioned in step b) refers to 2 to 5 stages of devolatilization.

8. The preparation method according to claim 7, characterized in that, The conditions and parameters for each stage of devolatilization are as follows: The screw has 5 to 15 cylinder steps, 4 to 7 vacuum ports, a vacuum pressure of -0.3 MPa to 0.01 MPa, a temperature of 150℃ to 250℃ for each cylinder, a rotation speed of 50 rpm to 200 rpm, a polymer flow rate of 10 kg / h to 200 kg / h in the screw, and a residence time of 3 min to 30 min.

9. A thermoplastic polyolefin elastomer resistant to ultraviolet aging, characterized in that, It is prepared by the preparation method described in any one of claims 1 to 8.

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