CN111848845B - Catalyst for preparing low-entanglement ultrahigh molecular weight polyethylene and preparation method thereof - Google Patents
Catalyst for preparing low-entanglement ultrahigh molecular weight polyethylene and preparation method thereof Download PDFInfo
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Abstract
The invention provides a catalyst for preparing low-entanglement ultrahigh molecular weight polyethylene, which comprises a nano hydrotalcite carrier and a titanium active component loaded on the nano hydrotalcite, wherein when the catalyst and a cocatalyst are used for catalyzing polyethylene together, the consumption of the cocatalyst is small, UHMWPE resin is not adhered to a kettle, and the entanglement degree is low; the invention also provides a preparation method of the catalyst, and the dried nano hydrotalcite is used as a carrier, so that the Zieglar-Natta catalyst with larger spacing distance between active points can be obtained, the chain entanglement process is inhibited, the viscosity of the prepared ultra-high molecular weight polyethylene is reduced, and the processing performance is improved.
Description
Technical Field
The invention relates to the technical field of polyethylene catalysts, in particular to a catalyst for preparing low-entanglement ultrahigh molecular weight polyethylene and a preparation method thereof.
Background
Ultra-high Molecular Weight Polyethylene (UHMWPE) for short is a polyolefin material with the Molecular Weight of more than 100 ten thousand g/mol, has high wear resistance, good biocompatibility, higher mechanical strength and other excellent performances, and can be used in the fields of hip joint and knee joint replacement, super-strong waterproof ropes, body armor and the like. However, due to the fact that the second molecular chain of the UHMWPE is too long, a plurality of topological limiting points or entanglement points exist in the polymer, the molecular chain of the UHMWPE is greatly restrained, after the UHMWPE is heated to the melting point, the UHMWPE melt presents a high-viscosity state, the melt viscosity can reach over 108 pas, the flow rate of the UHMWPE melt is very low and is almost 0, and therefore the critical shear rate of the UHMWPE also becomes very low. Thus, at lower shear rates, the polymer melt will fracture, greatly reducing the processability of UHMWPE. UHMWPE is generally not substantially processable by conventional processing methods and the articles have poor uniformity, which limits its use to some extent.
Rastogi S et al reported a low temperature-dilute solution homogeneous polymerization process for producing low entanglement UHMWPE (see "Novel Route to Fatigue-Resistant full Sintered ultra high Molecular Weight Polyethylene for Knee Prostisis", rastogi S et al, biomacromolecules, vol.6, no. 2, p. 942-947). The extremely dilute catalyst concentration in homogeneous polymerization increases the distance of primary chain segments, effectively reduces the occurrence probability of chain-to-chain overlapping, and effectively reduces the chain entanglement degree. However, the homogeneous polymerization, the reactor fouling, and the sticking of the viscous polymer to the reactor surface are disadvantageous for the industrialization.
EP14418861 discloses a UHMWPE using a single site catalyst (metallocene catalyst) to obtain a very low entanglement density, but this catalyst requires the use of large amounts of expensive co-catalyst (methylaluminoxane) to ensure high activity of the catalyst, increasing production costs.
CN108440691A discloses a method for preparing ultra-fine ultra-high molecular weight polyethylene, which utilizes the three-dimensional nano-size effect of polysilsesquioxane and the technology of ultrasonic polymerization while ultrasonic polymerization to increase the distance between catalysts, thereby inhibiting the overlapping occurrence probability in the polymerization process and preparing low-entanglement ultra-fine UHMWPE, but the price of polysilsesquioxane used in the method is extremely expensive and is not beneficial to industrial production, and the preparation of the low-entanglement ultra-fine UHMWPE is realized by adopting the mode of ultrasonic catalyst distance increase, which has no stability and controllability, and the obtained low-entanglement ultra-fine UHMWPE is difficult to guarantee.
In view of the foregoing, there is a need to develop a catalyst for preparing low entanglement ultra high molecular weight polyethylene that alleviates the processing difficulties of existing ultra high molecular weight polyethylene.
Disclosure of Invention
In order to solve the technical problems, the invention provides a catalyst for preparing low-entanglement ultrahigh molecular weight polyethylene, which comprises a nano hydrotalcite carrier and a titanium active component loaded on the nano hydrotalcite, wherein when the catalyst and a cocatalyst catalyze polyethylene together, the consumption of the cocatalyst is small, so that the problems of large consumption of the cocatalyst, scaling of a reactor and the like in the traditional process technology are solved, and the obtained ultrahigh molecular weight polyethylene has the advantages of high molecular weight, low entanglement degree, good processability and the like, and has wide application prospect in the fields of fibers and plates.
In order to achieve the purpose, the invention adopts the following technical scheme:
in a first aspect, the present invention provides a catalyst for preparing low-entanglement ultrahigh molecular weight polyethylene, which comprises a nano hydrotalcite carrier and a titanium active component supported on the nano hydrotalcite.
The catalyst provided by the invention takes the nano hydrotalcite as a carrier, and the distance of active sites on the carrier is relatively large, so that the chain entanglement process is inhibited, the viscosity of the prepared ultrahigh molecular weight polyethylene is reduced, and the processability is improved; moreover, the catalyst is a carrier type Zieglar-Natta catalyst, and the heterogeneous polymerization is carried out, so that the phenomenon of sticking to a kettle is avoided, the consumption of a cocatalyst is low, and the industrial production is facilitated.
The low-entanglement ultrahigh molecular weight polyethylene refers to ultrahigh molecular weight polyethylene with chain entanglement degree Go/Gmax less than or equal to 0.85.
Preferably, the mass fraction of the titanium active component in the catalyst is 0.5 to 15wt%, for example 0.5wt%, 1wt%, 1.5wt%, 2wt%, 2.5wt%, 3wt%, 3.5wt%, 4wt%, 5wt%, 8wt%, 10wt%, 12wt% or 15wt%, etc., preferably 2 to 8wt%.
Preferably, the nano hydrotalcite is a hydrotalcite comprising general formula Mg 6 Al 2 (OH) 16 CO 3 ·4H 2 A mineral of O.
Preferably, mg in the nano hydrotalcite 6 Al 2 (OH) 16 CO 3 ·4H 2 The mass fraction of O is 95wt% or more, and may be 95wt%, 95.5wt%, 96wt%, 96.5wt%, 97wt%, 97.5wt%, 98wt%, 98.5wt%, or the like, for example.
Preferably, the D50 of the nano-hydrotalcite is 5 to 200nm, and may be, for example, 5nm, 10nm, 20nm, 30nm, 40nm, 50nm, 80nm, 100nm, 120nm, 140nm, 150nm, 180nm, 200nm, or the like.
Preferably, the specific surface area of the nano hydrotalcite is 30 to 500m 2 A value of/g, for example, may be 30m 2 /g、50m 2 /g、100m 2 /g、150m 2 /g、200m 2 /g、250m 2 /g、300m 2 /g、350m 2 /g、400m 2 /g、450m 2 G or 500m 2 G, etc., preferably 150 to 380m 2 /g。
Preferably, the pore volume of the nano hydrotalcite is 0.5 to 10mL/g, and may be, for example, 0.5mL/g, 1mL/g, 2mL/g, 3mL/g, 4mL/g, 5mL/g, 6mL/g, 7mL/g, 8mL/g, 9mL/g, or 10mL/g, etc.
Preferably, the nano hydrotalcite is a sheet structure.
In a second aspect, the present invention provides a process for preparing a catalyst for use in the preparation of low entanglement ultra high molecular weight polyethylene, the process comprising the steps of:
(1) Mixing the dried nano hydrotalcite with a solvent I and a chemical activating agent, reacting to obtain a pre-carrier, and cleaning the pre-carrier by using a solvent II to obtain a carrier;
(2) And mixing the carrier with a titanium source, carrying out titanium-carrying reaction, and washing to obtain the catalyst.
The nano hydrotalcite provided by the invention is mixed with a solvent I and a chemical activator for reaction and cleaning to obtain a carrier, and the carrier is mixed with a titanium source for cleaning to obtain the catalyst. According to the invention, the nano-hydrotalcite is dried and then mixed with the solvent I and the chemical activating agent to participate in the reaction, and the nano-hydrotalcite is dried and then participates in the reaction preferentially, so that the hydroxyl content on the surface of the nano-hydrotalcite can be effectively controlled, the distance between active sites is increased, and the purpose of finally controlling the entanglement degree of the prepared polyethylene is achieved.
Preferably, the nano hydrotalcite in the step (1) comprises Mg 6 Al 2 (OH) 16 CO 3 ·4H 2 And (4) minerals of the general formula O.
The nano hydrotalcite of the invention comprises Mg 6 Al 2 (OH) 16 CO 3 ·4H 2 The natural minerals of the general formula O have wide sources and clear main components.
Preferably, mg in the nano hydrotalcite 6 Al 2 (OH) 16 CO 3 ·4H 2 The mass fraction of O is 95wt% or more, and may be 95wt%, 95.5wt%, 96wt%, 96.5wt%, 97wt%, 97.5wt%, 98wt%, 98.5wt%, or the like, for example.
Preferably, the D50 of the nano-hydrotalcite is 5 to 200nm, and may be, for example, 5nm, 10nm, 20nm, 30nm, 40nm, 50nm, 80nm, 100nm, 120nm, 140nm, 150nm, 180nm, 200nm, or the like.
Preferably, the specific surface area of the nano hydrotalcite is 30 to 500m 2 Per g, may be, for example, 30m 2 /g、50m 2 /g、100m 2 /g、150m 2 /g、200m 2 /g、250m 2 /g、300m 2 /g、350m 2 /g、400m 2 /g、450m 2 G or 500m 2 G, etc., preferably 150 to 380m 2 /g。
The specific surface of the nano hydrotalcite in the invention is preferably 150 to 380m 2 The specific surface area is high, the loading effect is better, the distance between active sites is proper, and the entanglement degree of the prepared polyethylene can be effectively reduced.
Preferably, the pore volume of the nano-hydrotalcite is 0.5 to 10mL/g, for example, 0.5mL/g, 1mL/g, 2mL/g, 3mL/g, 4mL/g, 5mL/g, 6mL/g, 7mL/g, 8mL/g, 9mL/g, or 10mL/g, and the like.
Preferably, the nano hydrotalcite is a sheet structure.
Preferably, the nano-hydrotalcite has an initial ignition loss of 5 to 30wt%, for example, may be 5wt%, 10wt%, 15wt%, 18wt%, 20wt%, 22wt%, 25wt%, 28wt%, or 30wt%, etc.
Preferably, the chemical activator comprises organomagnesium and/or organoaluminum.
Preferably, the organomagnesium reagent comprises butyloctylmagnesium, tert-butylmagnesium chloride or a combination of any one or at least two of butylmagnesium chloride, trimethylaluminum, triethylaluminum, dimethylaluminum chloride, tributylaluminum, with typical non-limiting combinations being the combination of butyloctylmagnesium and tert-butylmagnesium chloride, the combination of butyloctylmagnesium and butylmagnesium chloride, the combination of tert-butylmagnesium chloride and butylmagnesium chloride, the combination of trimethylaluminum and tributylaluminum, the combination of triethylaluminum and tert-butylmagnesium chloride, the combination of dimethylaluminum chloride and tetrabutylmagnesium chloride, preferably butylmagnesium chloride.
The compounding ratio of the chemical activator to the nano hydrotalcite is preferably 0.1 to 0.5mol, and may be, for example, 0.1mol.
The concentration of the organic magnesium reagent or the organic aluminum reagent in the chemical activator and the proportion of the organic magnesium reagent or the organic aluminum reagent to the nano-hydrotalcite are controlled within the range, so that the combination and the reaction of the chemical activator and the hydroxyl on the surface of the nano-hydrotalcite can be better guaranteed.
Preferably, the solvent i is a saturated hydrocarbon and/or ether compound having 4 to 20 carbon atoms, the number of carbon atoms may be, for example, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 or 20, the solvent i may be, for example, any one or a combination of at least two of n-butane, isobutane, methylcyclopentane, n-pentane, n-hexane, cyclohexane, n-octane, n-heptane, n-decane, nonane, tetrahydrofuran, diethyl ether or dimethoxymethane, typical non-limiting combinations thereof are a combination of n-butane and n-decane, a combination of n-butane and nonane, a combination of n-butane and tetrahydrofuran, a combination of n-decane and tetrahydrofuran, a combination of tetrahydrofuran and nonane, a combination of nonane and n-hexane, a combination of tetrahydrofuran and n-hexane, a combination of n-hexane and diethyl ether, a combination of diethyl ether and dimethoxymethane, preferably n-hexane.
Preferably, the mass ratio of the solvent i to the nano-hydrotalcite is 12 to 18, and can be, for example, 12.
Preferably, the solvent II is a saturated hydrocarbon and/or ether compound having 4 to 20 carbon atoms, the number of carbon atoms may be, for example, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 or 20, the solvent I may be, for example, any one or a combination of at least two of n-butane, isobutane, methylcyclopentane, n-pentane, n-hexane, cyclohexane, n-octane, n-heptane, n-decane, nonane, tetrahydrofuran, diethyl ether or dimethoxymethane, typical non-limiting combinations thereof are a combination of n-butane and n-decane, a combination of n-butane and nonane, a combination of n-butane and tetrahydrofuran, a combination of n-decane and tetrahydrofuran, a combination of tetrahydrofuran and nonane, a combination of nonane and n-hexane, a combination of tetrahydrofuran and n-hexane, a combination of n-hexane and diethyl ether, a combination of diethyl ether and dimethoxymethane, preferably n-hexane.
Preferably, the mass ratio of the solvent ii to the nano hydrotalcite is 5 to 18, and may be 5:1, 6:1, 7:1, 8:1, 9:1, 10.
Preferably, the nano hydrotalcite is dried and then mixed with the solvent I and the chemical activating agent.
Preferably, the drying temperature in step (1) is 200 to 500 ℃, for example, 200 ℃, 250 ℃, 300 ℃, 350 ℃, 400 ℃, 450 ℃ or 500 ℃ and the like.
Preferably, the drying time is 1 to 10 hours, and may be, for example, 1 hour, 1.5 hours, 2 hours, 2.5 hours, 3 hours, 3.25 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, or the like.
Preferably, the drying is carried out in an inert atmosphere.
Preferably, the drying reduces the ignition loss of the nano-hydrotalcite to 1 to 12%, for example, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, or 12% or the like.
The ignition loss of the nano hydrotalcite is preferably reduced to 1-12%, and in the range, a certain amount of titanium source and chemical activator can be supported, and the problem that the entanglement degree of polyethylene is increased due to too close active site distance can be avoided.
Preferably, the reaction temperature in step (1) is 30 to 80 ℃, for example, 30 ℃, 35 ℃, 40 ℃, 45 ℃, 50 ℃, 55 ℃,60 ℃, 65 ℃, 70 ℃, 75 ℃ or 80 ℃.
Preferably, the reaction time is 0.5 to 3 hours, and may be, for example, 0.5 hour, 1 hour, 1.5 hours, 2 hours, 2.5 hours, 3 hours, or the like.
Preferably, the reaction is carried out under stirring conditions.
Preferably, the number of washes is 2 to 5, and may be, for example, 2, 3, 4 or 5.
Preferably, the titanium source in step (2) comprises titanium tetrachloride.
Preferably, an electron donor is added in the titanium-carrying reaction.
Preferably, the electron donor comprises any one or a combination of at least two of diethers, aromatic carboxylic diesters or siloxanes, wherein typical non-limiting combinations are combinations of diethers and aromatic carboxylic diesters, combinations of diethers and siloxanes, combinations of aromatic carboxylic diesters and siloxanes, further such as any one or a combination of at least two of ethyl p-toluate, diethylbutylphthalate, 2-ethyl-2-butyl-1,3-dimethoxypropane, γ -chloropropyltriethoxysilane, dicyclopentyldimethoxysilane, wherein typical non-limiting combinations are combinations of ethyl p-toluate and diethylbutylphthalate, combinations of ethyl p-toluate and γ -chloropropyltriethoxysilane, combinations of diethylbutylphthalate and 2-ethyl-2-butyl-1,3-dimethoxypropane, combinations of 2-ethyl-2-butyl-1,3-dimethoxypropane and γ -chloropropyltriethoxysilane, preferably combinations of γ -chloropropyltriethoxysilane and dicyclopentyltriethoxysilane, preferably combinations of γ -chloropropyltriethoxysilane.
Preferably, the mass ratio of the titanium source to the nano-hydrotalcite is 10 to 16, and may be, for example, 10.
Preferably, the mass ratio of the electron donor to the nano hydrotalcite is 0.1 to 5:1, and may be, for example, 0.1.
Preferably, the temperature of the titanium-carrying reaction is 20 to 80 ℃, and may be, for example, 20 ℃, 25 ℃,30 ℃, 35 ℃, 40 ℃, 45 ℃, 50 ℃, 55 ℃,60 ℃, 65 ℃, 70 ℃, 75 ℃ or 80 ℃.
Preferably, the reaction time of the titanium-carrying reaction is 1 to 5 hours, and may be, for example, 1 hour, 1.5 hours, 2 hours, 2.5 hours, 3 hours, 3.5 hours, 4 hours, 4.5 hours, 5 hours, or the like.
Preferably, the washing liquid is an alkane solvent, preferably n-hexane.
As a preferred technical scheme of the invention, the method comprises the following steps:
(1) Mixing the dried nano hydrotalcite with the ignition loss reduced to 1-12%, a chemical activating agent and a solvent I, reacting at 30-80 ℃ for 0.5-3 h to obtain a pre-carrier, and cleaning the pre-carrier by using a solvent II to obtain a carrier;
wherein Mg in the nano hydrotalcite 6 Al 2 (OH) 16 CO 3 ·4H 2 The mass fraction of O is more than or equal to 95wt%, the initial ignition loss of the nano hydrotalcite is 5-30%, and the solvent I is carbon atom numberThe catalyst is a saturated hydrocarbon and/or ether compound with 4-20 carbon atoms, the solvent II is a saturated hydrocarbon and/or ether compound with 4-20 carbon atoms, the ratio of the chemical activator to the nano-hydrotalcite is 0.1-0.5 mol, the mass ratio of the solvent I to the nano-hydrotalcite is 12-18;
(2) Mixing the carrier and a titanium source, adding an electron donor, carrying out titanium-carrying reaction at 20-80 ℃ for 1-5 h, and washing to obtain a catalyst;
wherein the electron donor comprises one or the combination of at least two of diether, aromatic carboxylic diester or siloxane compounds, the mass ratio of the titanium source to the nano hydrotalcite is 10-16, and the mass ratio of the electron donor to the nano hydrotalcite is 0.1-5:1.
In a third aspect, the present invention provides a process for the preparation of low-entanglement ultrahigh-molecular-weight polyethylene using the catalyst of the first aspect.
The catalyst provided by the first aspect is adopted to prepare the low-entanglement ultrahigh molecular weight polyethylene, and because the active site spacing in the catalyst is large, the finally prepared ultrahigh molecular weight polyethylene has low entanglement degree and strong processability.
Preferably, the method comprises the steps of: mixing solvent III, cocatalyst, catalyst and ethylene, and carrying out polymerization reaction to obtain the low-entanglement ultrahigh molecular weight polyethylene.
Preferably, the solvent III comprises saturated and/or aromatic hydrocarbons with a carbon number of 4 to 10, which may be, for example, 4, 5, 6, 7, 8, 9 or 10, and the solvent III may be, for example, any one or a combination of at least two of n-butane, isobutane, methylcyclopentane, n-hexane, n-heptane, n-decane or nonane toluene, with typical non-limiting combinations being a combination of n-butane and isobutane, n-butane and methylcyclopentane, n-butane and n-heptane, methylcyclopentane and n-heptane, n-heptane and nonane toluene, nonane toluene and n-decane, preferably n-hexane.
Preferably, the cocatalyst comprises any one of or a combination of at least two of an aluminum alkyl, an aluminum alkoxide or an aluminum chloroalkyl.
The alkyl aluminum preferably has 1 to 10 carbon atoms, and may be, for example, 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10 carbon atoms, and is preferably triethylaluminum.
The aluminum alkoxide preferably has 1 to 10 carbon atoms, and may be, for example, 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10.
The alkylaluminum chloride preferably has 1 to 10 carbon atoms, and may be, for example, 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10.
Preferably, the ratio of the cocatalyst to the solvent iii is 0.001 to 0.01mol, and for example, it may be 0.001mol.
The proportion of the cocatalyst to the solvent III is 0.001-0.01mol, preferably 0.001-0.005mol, 1L, the cocatalyst is low in dosage, and the problems of scaling of the existing reactor and the like are solved.
The ratio of the catalyst to the solvent iii is preferably 50 to 90mg, and for example, 501l, 52mg, 1l, 58mg.
Preferably, the polymerization reaction temperature is 20 to 90 ℃, for example, 20 ℃, 25 ℃,30 ℃, 35 ℃, 40 ℃, 45 ℃, 50 ℃,60 ℃, 70 ℃,80 ℃ or 90 ℃.
The pressure of the polymerization reaction is preferably 0.1 to 2MPa, and may be, for example, 0.1MPa, 0.3MPa, 0.4MPa, 0.5MPa, 0.8MPa, 1.0MPa, 1.2MPa, 1.5MPa, 1.8MPa or 2MPa.
Preferably, the polymerization reaction time is 0.5 to 10 hours, and may be, for example, 0.5 hour, 1 hour, 1.5 hours, 2.0 hours, 2.5 hours, 3 hours, 3.5 hours, 4.0 hours, 4.5 hours, 5 hours, 5.5 hours, 6 hours, 7 hours, 7.5 hours, 8 hours, 8.5 hours, 9 hours, 10 hours, or the like.
Compared with the prior art, the invention has at least the following beneficial effects:
(1) The catalyst for preparing the low-entanglement ultrahigh molecular weight polyethylene is a carrier type Zieglar-Natta catalyst, adopts nano hydrotalcite as a carrier, is connected with a titanium active component, has high catalytic performance, and has no kettle adhesion phenomenon and less cocatalyst consumption through heterogeneous polymerization;
(2) According to the preparation method of the catalyst for preparing the low-entanglement ultrahigh molecular weight polyethylene, provided by the invention, hydrotalcite with different hydroxyl contents is obtained by adjusting drying conditions, a magnesium activator is inoculated and reacts with titanium tetrachloride to obtain the catalyst with different active point spacing distances, and the chain entanglement process is inhibited by increasing the spacing distance of the active points, so that the viscosity of the prepared ultrahigh molecular weight polyethylene is reduced, and the processing performance is improved;
(3) The preparation method of the ultra-high molecular weight polyethylene provided by the invention comprehensively adopts the catalyst and controls the reaction conditions, so that the ultra-high molecular weight polyethylene with Go/Gmax of less than or equal to 0.82 can be finally prepared, and the Go/Gmax of less than or equal to 0.6 can be realized under the condition of combining the optimized reaction temperature and the ignition loss of the catalyst carrier, thereby improving the processing performance.
Detailed Description
For the purpose of facilitating an understanding of the present invention, the present invention will now be described by way of examples. It should be understood by those skilled in the art that the examples are only for the understanding of the present invention and should not be construed as the specific limitations of the present invention.
1. Examples of the embodiments
Example 1
The embodiment provides a catalyst for preparing low-entanglement ultrahigh molecular weight polyethylene, which comprises a nano hydrotalcite carrier and a titanium active component loaded on the nano hydrotalcite, wherein the mass fraction of the titanium active component in the catalyst is 10.5%.
The preparation method of the catalyst comprises the following steps:
(1) 10g of nano hydrotalcite is dried for 5 hours at 300 ℃ in a nitrogen atmosphere, and the ignition loss is reduced to 8.7wt%. Mixing 5g of dried nano hydrotalcite with 70mL of tetrahydrofuran solution with the concentration of butyl magnesium chloride being 0.02mol/mL, and continuously and uniformly stirring at 60 ℃ for reacting for 1h to obtain 5.35g of pre-carrier;
washing the pre-carrier for 3 times by respectively using 30g of tetrahydrofuran and 30g of normal hexane at 50 ℃ to remove excessive butyl magnesium chloride;
wherein, the properties of the nano hydrotalcite LDHs-M are as follows: the content of magnesium oxide is 41.5wt%, the particle diameter D50 is 100nm, the particle size distribution is 0.85, and the specific surface area is 210m 2 (iv)/g, loss on ignition of starting material 12.6%;
(2) Carrying out further titanium carrying reaction on the carrier, sequentially adding 60g of titanium tetrachloride and 2g of gamma-chloropropylethoxysilane into a reaction bottle filled with the carrier after vacuum nitrogen replacement, mixing at 60 ℃ for carrying out titanium carrying reaction for 2h, and then repeatedly washing with 30g of n-hexane for 3 times to obtain 6.7g of light yellow powder catalyst.
Example 2
The embodiment provides a catalyst for preparing low-entanglement ultrahigh molecular weight polyethylene, which comprises a nano hydrotalcite carrier and a titanium active component loaded on the nano hydrotalcite, wherein the mass fraction of the titanium active component in the catalyst is 7.2%.
The preparation method of the catalyst comprises the following steps:
(1) 10g of nano hydrotalcite LDHs-M is dried for 8 hours at 300 ℃ in a nitrogen atmosphere, and the ignition loss is reduced to 5.8wt%. Mixing 5g of dried nano hydrotalcite with 70mL of tetrahydrofuran solution with the concentration of butyl magnesium chloride being 0.02mol/mL, and continuously and uniformly stirring at 60 ℃ for reacting for 1h to obtain 5.22g of pre-carrier;
washing the pre-carrier with 30g of tetrahydrofuran and 30g of n-hexane respectively at 50 ℃ for 3 times to remove excessive butyl magnesium chloride;
wherein, the properties of the nano hydrotalcite LDHs-M are as follows: the content of magnesium oxide is 41.5wt%, the particle diameter D50 is 100nm, the particle size distribution is 0.85, and the specific surface area is 210m 2 (iv)/g, loss on ignition of starting material 12.6%;
(2) Carrying out further titanium carrying reaction on the carrier, sequentially adding 60g of titanium tetrachloride and 2g of gamma-chloropropylethoxysilane into a reaction bottle filled with the carrier after vacuum nitrogen replacement, mixing at 60 ℃ for carrying out titanium carrying reaction for 2h, and then repeatedly washing with 30g of n-hexane for 3 times to obtain 6.41g of light yellow powder catalyst.
Example 3
The embodiment provides a catalyst for preparing low-entanglement ultrahigh molecular weight polyethylene, which comprises a nano hydrotalcite carrier and a titanium active component loaded on the nano hydrotalcite, wherein the mass fraction of the titanium active component in the catalyst is 5.3%.
The preparation method of the catalyst comprises the following steps:
(1) 10g of nano hydrotalcite LDHs-M is dried for 10 hours at 300 ℃ in a nitrogen atmosphere, and the ignition loss is reduced to 4.3wt%. Mixing 5g of dried nano hydrotalcite with 70g of tetrahydrofuran solution with the concentration of butyl magnesium chloride being 0.02mol/mL, and continuously and uniformly stirring at 60 ℃ for reacting for 1h to obtain 5.13g of pre-carrier;
washing the pre-carrier with 30g of tetrahydrofuran and 30g of n-hexane respectively at 50 ℃ for 3 times to remove excessive butyl magnesium chloride;
wherein, the properties of the nano hydrotalcite LDHs-M are as follows: the content of magnesium oxide is 41.5wt%, the particle diameter D50 is 100nm, the particle size distribution is 0.85, and the specific surface area is 210m 2 (iv)/g, loss on ignition of starting material 12.6%;
(2) Carrying out further titanium carrying reaction on the carrier, sequentially adding 60g of titanium tetrachloride and 2g of gamma-chloropropylethoxysilane into a reaction bottle filled with the carrier after vacuum nitrogen replacement, mixing at 60 ℃ for carrying out titanium carrying reaction for 2h, and then repeatedly washing with 30g of n-hexane for 3 times to obtain 5.73g of light yellow powder catalyst.
Example 4
The present example provides a catalyst for preparing low-entanglement ultrahigh molecular weight polyethylene, which includes a nano hydrotalcite carrier and a titanium active component supported on the nano hydrotalcite, and the mass fraction of the titanium active component in the catalyst is 2.4%.
The preparation method of the catalyst comprises the following steps:
(1) 10g of nano hydrotalcite LDHs-M is dried for 10 hours at 250 ℃ in a nitrogen atmosphere, and the ignition loss is reduced to 2wt%. Mixing 5g of dried nano hydrotalcite with 60mL of diethyl ether solution with the concentration of butyl octyl magnesium being 0.04mol/mL, and continuously and uniformly stirring at 80 ℃ for reaction for 0.5h to obtain 5.05g of a pre-carrier;
washing the pre-carrier with 40g of diethyl ether and 30g of n-hexane respectively at 60 ℃ for 4 times to remove excessive butyl magnesium chloride;
wherein, the properties of the nano hydrotalcite LDHs-M are as follows: 43.5wt% of magnesium oxide, a particle diameter D50 of 150nm, a particle size distribution of 0.75, a specific surface area of 160m 2 (iv)/g, loss of starting material ignition of 19%;
(2) And (2) carrying out further titanium carrying reaction on the carrier, sequentially adding 70g of titanium tetrachloride and 8g of diethyl phthalate into a reaction bottle filled with the carrier after vacuum nitrogen replacement, mixing at 80 ℃ to carry out titanium carrying reaction for 1h, and repeatedly washing with 20g of n-hexane for 5 times to obtain 5.33g of a light yellow powder catalyst.
Example 5
The present example provides a catalyst for preparing low-entanglement ultrahigh molecular weight polyethylene, where the catalyst includes a nano hydrotalcite carrier and a titanium active component supported on the nano hydrotalcite, and a mass fraction of the titanium active component in the catalyst is 14.2%.
The preparation method of the catalyst comprises the following steps:
(1) 10g of nano hydrotalcite LDHs-M is dried for 1h at 500 ℃ in a nitrogen atmosphere, and the ignition loss is reduced to 12wt%. Mixing 5g of dried hydrotalcite with 90mL of dimethoxymethane solution with the concentration of butyl octyl magnesium being 0.01mol/mL, and continuously and uniformly stirring at 30 ℃ for reaction for 3h to obtain 5.78g of pre-carrier;
washing the pre-load with n-hexane 30g at 50 ℃ for 3 times to remove excess butyl magnesium chloride;
wherein, the properties of the nano hydrotalcite LDHs-M are as follows: the content of magnesium oxide is 46.5wt%, the particle diameter D50 is 85nm, the particle size distribution is 0.66, and the specific surface area is 347m 2 (iv)/g, loss of starting material ignition of 22%;
(2) The carrier is further subjected to titanium carrying reaction, 60g of titanium tetrachloride and 8g of dicyclopentyldimethoxysilane are sequentially added into a reaction bottle filled with the carrier after vacuum nitrogen replacement, the mixture is mixed at 20 ℃ for carrying titanium reaction for 5 hours, and then 20g of n-hexane is used for repeated washing for 5 times to obtain 6.23g of light yellow powder catalyst.
Example 6
The present example provides a catalyst for preparing low-entanglement ultrahigh molecular weight polyethylene, which includes a nano hydrotalcite carrier and a titanium active component supported on the nano hydrotalcite, and the mass fraction of the titanium active component in the catalyst is 14.5%.
The preparation method of the catalyst is the same as that of the example 3 except that the nano hydrotalcite is naturally aired in the step (1) and the ignition loss is still 12.6 wt%.
The method for testing the ignition loss in the above embodiment includes: the sample was subjected to two-step heating: the weight loss experienced by the sample was determined as the ignition loss by first heating in a drying oven at 200 ℃ for 30 minutes and then heating in a muffle furnace at 950 ℃ for 1 hour.
Comparative example 1
This comparative example provides a catalyst for preparing ultra-high molecular weight polyethylene, which employs magnesium chloride as a carrier instead of dried nano hydrotalcite, and the rest is the same as example 3.
The preparation method specifically comprises the following steps:
(1) In tetrahydrofuran solution, 5g of magnesium powder is mixed with 70mL of n-butyl chloride, and the mixture is continuously and uniformly stirred at 85 ℃ for reaction for 1h to obtain 8.5g of pre-carrier active magnesium chloride;
washing the pre-carrier for 3 times at 50 ℃ by respectively using 30g of tetrahydrofuran and 30g of normal hexane to remove excessive n-butyl chloride;
(2) Carrying out further titanium carrying reaction on the carrier, sequentially adding 60g of titanium tetrachloride and 2g of gamma-chloropropylethoxysilane into a reaction bottle filled with 5g of the carrier after vacuum nitrogen replacement, mixing at 60 ℃ to carry out titanium carrying reaction for 2 hours, and then repeatedly washing with 30g of n-hexane for 3 times to obtain 5.10g of light yellow powder catalyst.
2. Application example
Application example 1
The present application example provides a process for preparing low entanglement ultra-high molecular weight polyethylene, the process comprising the steps of:
after nitrogen substitution in a 10L reactor, 5L of n-hexane, 10mL of 1mol/L triethylaluminum, and 300mg of the catalyst prepared in example 1 were sequentially added, and then ethylene was introduced, followed by polymerization at 50 ℃ and 0.6MPa for 1 hour to obtain 800g of UHMWPE.
Application example 2
The present application example provides a process for preparing low entanglement ultra-high molecular weight polyethylene, the process comprising the steps of:
after nitrogen replacement in a 10L reactor, 5L of n-hexane, 10mL of 1mol/L triethylaluminum, and 400mg of the catalyst prepared in example 2 were sequentially added, and then ethylene was introduced to conduct polymerization at 50 ℃ and 0.6MPa for 1 hour to obtain 927g of UHMWPE.
Application example 3
The present application example provides a process for preparing low entanglement ultra-high molecular weight polyethylene, the process comprising the steps of:
after nitrogen replacement in a 10L reactor, 5L of n-hexane, 10mL of 1mol/L triethylaluminum, and 500mg of the catalyst prepared in example 3 were sequentially added, and then ethylene was introduced to conduct polymerization at 50 ℃ and 0.6MPa for 1 hour to obtain 753g of UHMWPE.
Application example 4
The present application example provides a process for preparing low entanglement ultra high molecular weight polyethylene, the process comprising the steps of:
after nitrogen replacement in a 10L reactor, 5L of n-hexane, 10mL of 1mol/L triethylaluminum, and 300mg of the catalyst prepared in example 1 were sequentially added, and then ethylene was introduced to conduct polymerization at 70 ℃ and 0.6MPa for 1 hour to obtain 458g of UHMWPE.
Application example 5
The present application example provides a process for preparing low entanglement ultra-high molecular weight polyethylene, the process comprising the steps of:
after nitrogen replacement in a 10L reactor, 5L of n-hexane, 10mL of 1mol/L triethylaluminum, and 300mg of the catalyst prepared in example 1 were sequentially added, and then ethylene was introduced to conduct polymerization at 30 ℃ and 0.6MPa for 1 hour to obtain 350g of UHMWPE.
Application example 6
The present application example provides a process for preparing low entanglement ultra-high molecular weight polyethylene, the process comprising the steps of:
after nitrogen replacement in a 10L reactor, 5L of n-hexane, 10mL of 1mol/L triethylaluminum, and 300mg of the catalyst prepared in example 1 were sequentially added, and then ethylene was introduced to conduct polymerization at 20 ℃ and 0.6MPa for 2 hours, thereby obtaining 480g of UHMWPE.
Application example 7
The present application example provides a process for preparing low entanglement ultra high molecular weight polyethylene, the process comprising the steps of:
after nitrogen replacement in a 10L reactor, 5L of n-hexane, 10mL of 1mol/L triethylaluminum, and 300mg of the catalyst prepared in example 3 were sequentially added, and then ethylene was introduced to conduct polymerization at 20 ℃ and 0.6MPa for 2 hours, thereby obtaining 210g of UHMWPE.
Application example 8
The present application example provides a process for preparing low entanglement ultra-high molecular weight polyethylene, the process comprising the steps of:
after a 10L reactor was purged with nitrogen, 4.5L of n-heptane, 12mL of 1mol/L diethylaluminum monochloride, and 450mg of the catalyst prepared in example 4 were sequentially added, and then ethylene was introduced to conduct polymerization at 20 ℃ and 2MPa for 3 hours, thereby obtaining 268g of UHMWPE.
Application example 9
The present application example provides a process for preparing low entanglement ultra high molecular weight polyethylene, the process comprising the steps of:
after nitrogen substitution in a 10L reactor, 5L of butane, 15mL0.8mol/L of triisobutylaluminum and 500mg of the catalyst prepared in example 5 were sequentially added, and then ethylene was introduced to conduct polymerization at 80 ℃ and 0.1MPa for 0.5h, whereby 762g of UHMWPE was obtained.
Application example 10
This application example provides a process for preparing low entanglement ultra high molecular weight polyethylene which is the same as application example 3 except that the catalyst provided in example 6 is used, yielding UHMWPE825g.
Application comparative example 1
This application example provides a process for preparing low entanglement ultra high molecular weight polyethylene which is the same as application example 3 except that the catalyst provided in comparative example 1 was used, yielding UHMWPE635g.
3. Test and results
The viscosity average molecular weight and the degree of chain entanglement of the UHMWPE produced in the above application examples and application comparative examples were measured by the following test methods.
And (3) testing the storage modulus: the storage modulus of UHMWPE was determined with time at 160 ℃ with an angular frequency of 10rad/s, constant stress of 0.5%, using a rotor rheometer. The chain entanglement degree is characterized by the ratio of initial storage modulus (Go) to maximum storage modulus (Gmax), the smaller Go/Gmax is, the smaller the chain entanglement degree is, and the Go/Gmax is generally considered to be low-entanglement polyethylene with the value of less than or equal to 0.85; wherein the initial storage modulus (Go) is a storage modulus at t =100 seconds, and the maximum storage modulus (Gmax) is a modulus at which the storage modulus does not change with the test time.
Viscosity average molecular weight test: the viscosity average molecular weight of the ultra-high molecular weight polyethylene is measured by adopting a high-temperature dilution Ubbelohde viscometer method, the inner diameter of a capillary is 0.44mm, a constant-temperature bath medium is No. 300 silicone oil, a solvent for dilution is decahydro tea, and the measurement temperature is 135 ℃. Viscosity average molecular weight: m η =5.34 × 10 4 [η] 1.37 。
The test results of the above application examples and comparative application examples are shown in table 1.
TABLE 1
From table 1, the following points can be seen:
(1) It can be seen from comprehensive application examples 1 to 10 that the application examples 1 to 10 can prepare the ultra-high molecular weight polyethylene with the chain entanglement degree Go/Gmax of not more than 0.82 and the viscosity average molecular weight of not less than 180 ten thousand by using the catalyst using the nano hydrotalcite as the carrier, wherein the application examples 2 to 3 combine and select the reaction temperature and the ignition loss of the nano hydrotalcite in the catalyst in the application examples 5 to 8, the chain entanglement degree Go/Gmax of the prepared ultra-high molecular weight polyethylene is not more than 0.6, and the processability of the ultra-high molecular weight polyethylene is greatly improved;
(2) By combining application example 3 and application comparative example 1, it can be seen that, compared with the catalyst using magnesium chloride as a carrier in application comparative example 1, the catalyst using nano hydrotalcite as a carrier in application example 3 has Go/Gmax of 0.23, and the catalyst using magnesium chloride as a carrier in application comparative example 1 has Go/Gmax of 0.87, thereby indicating that the chain entanglement process is inhibited and the viscosity of the prepared ultrahigh molecular weight polyethylene is reduced by selecting a catalyst using nano hydrotalcite as a carrier and titanium as an active component;
(3) It can be seen from the combination of application example 3 and application example 10 that the ignition loss of the nano hydrotalcite in application example 3 is controlled to be 4.3wt%, compared with the ignition loss of the nano hydrotalcite in application example 10 being 12.6%, go/Gmax in application example 3 is 0.23, and Go/Gmax in application example 10 is 0.80, which shows that the invention obtains the catalyst with active sites having a certain spacing distance by strictly controlling the ignition loss of the nano hydrotalcite, and reduces the chain entanglement degree of the ultrahigh molecular weight polyethylene.
In conclusion, the catalyst provided by the invention comprises a nano hydrotalcite carrier and a titanium active component loaded on the nano hydrotalcite, when the catalyst and a cocatalyst are used for catalyzing polyethylene together, the consumption of the cocatalyst is small, the prepared UHMWPE resin is not sticky to a kettle, the entanglement degree is low, the Go/Gmax is less than or equal to 0.82, the viscosity average molecular weight is more than or equal to 180 ten thousand, and the Go/Gmax is less than or equal to 0.6 under better conditions, and the prepared ultrahigh molecular weight polyethylene has strong processability.
The applicant states that the present invention is illustrated by the above examples to show the detailed process equipment and process flow of the present invention, but the present invention is not limited to the above detailed process equipment and process flow, i.e. it does not mean that the present invention must rely on the above detailed process equipment and process flow to be implemented. It should be understood by those skilled in the art that any modification of the present invention, equivalent substitutions of the raw materials of the product of the present invention, addition of auxiliary components, selection of specific modes, etc., are within the scope and disclosure of the present invention.
Claims (55)
1. The catalyst for preparing the low-entanglement ultrahigh molecular weight polyethylene is characterized by comprising a nano hydrotalcite carrier and a titanium active component loaded on the nano hydrotalcite, wherein the mass fraction of the titanium active component in the catalyst is 0.5-15 wt%, and the nano hydrotalcite comprises a general formula Mg 6 Al 2 (OH) 16 CO 3 ·4H 2 A mineral of O;
the preparation method of the catalyst comprises the following steps:
(1) Mixing dried nano-hydrotalcite with a solvent I and a chemical activator, wherein the ignition loss of the nano-hydrotalcite is reduced to 1-12% by drying, the chemical activator comprises an organic magnesium reagent and/or an organic aluminum reagent, the proportion of the chemical activator to the nano-hydrotalcite is 1 g/1-0.5 mol, obtaining a pre-carrier after reaction, and cleaning the pre-carrier by using a solvent II to obtain a carrier;
(2) And mixing the carrier and a titanium source, carrying out titanium-carrying reaction, and then washing, wherein an electron donor is added in the titanium-carrying reaction to obtain the catalyst.
2. The catalyst according to claim 1, wherein the mass fraction of the titanium active component in the catalyst is 2-8 wt%.
3. Catalyst according to claim 1, characterized in that the nano-hydrotalcite has Mg therein 6 Al 2 (OH) 16 CO 3 ·4H 2 The mass fraction of O is more than or equal to 95wt percent.
4. The catalyst according to claim 1, characterized in that the D50 of the nano-hydrotalcite is between 5 and 200nm.
5. The catalyst according to claim 1, wherein the nano hydrotalcite has a specific surface area of 30 to 500m 2 /g。
6. The catalyst according to claim 1, wherein the pore volume of the nano hydrotalcite is 0.5 to 10mL/g.
7. The catalyst according to claim 1, characterized in that the nano-hydrotalcite is a platelet structure.
8. A method for preparing a catalyst for use in the preparation of low entanglement ultra high molecular weight polyethylene, the method comprising the steps of:
(1) Mixing dried nano-hydrotalcite with a solvent I and a chemical activator, wherein the ignition loss of the nano-hydrotalcite is reduced to 1-12% by drying, the chemical activator comprises an organic magnesium reagent and/or an organic aluminum reagent, the proportion of the chemical activator to the nano-hydrotalcite is 1 g/1-0.5 mol, obtaining a pre-carrier after reaction, and cleaning the pre-carrier by using a solvent II to obtain a carrier;
(2) And mixing the carrier and a titanium source, carrying out titanium-carrying reaction, and then washing, wherein an electron donor is added in the titanium-carrying reaction to obtain the catalyst.
9. The process according to claim 8, wherein the nano hydrotalcite of step (1) is one comprising Mg 6 Al 2 (OH) 16 CO 3 ·4H 2 And (4) minerals of the general formula O.
10. The process according to claim 9, characterized in that the nano-hydrotalcite has Mg therein 6 Al 2 (OH) 16 CO 3 ·4H 2 The mass fraction of O is more than or equal to 95wt%.
11. The process according to claim 8, characterized in that the D50 of the nano-hydrotalcite is between 5 and 200nm.
12. The method according to claim 8, wherein the nano hydrotalcite has a specific surface area of 30 to 500m 2 /g。
13. The process according to claim 12, characterized in that the nano-hydrotalcite has a specific surface area of 150 to 380m 2 /g。
14. The method according to claim 8, wherein the nano hydrotalcite has a pore volume of 0.5 to 10mL/g.
15. The process according to claim 8, characterized in that the nano-hydrotalcite is a platelet structure.
16. The process according to claim 8, wherein the nano hydrotalcite has an initial ignition loss of 5 to 30wt%.
17. The process of claim 8, wherein the organomagnesium reagent comprises any one of, or a combination of at least two of, butyloctylmagnesium, tert-butylmagnesium chloride, or butylmagnesium chloride.
18. The process of claim 17, wherein the organomagnesium reagent is butyl magnesium chloride.
19. The method according to claim 8, wherein the solvent I is a saturated hydrocarbon and/or ether compound having 4 to 20 carbon atoms.
20. The method as claimed in claim 19, wherein the solvent i is n-hexane.
21. The method according to claim 8, wherein the mass ratio of the solvent I to the nano hydrotalcite is 12 to 18.
22. The method according to claim 8, wherein the solvent II is a saturated hydrocarbon and/or an ether compound having 4 to 20 carbon atoms.
23. The method as claimed in claim 22, wherein the solvent ii is n-hexane.
24. The method according to claim 8, wherein the mass ratio of the solvent II to the nano hydrotalcite is 5 to 18.
25. The method according to claim 8, wherein the drying temperature in step (1) is 200-500 ℃.
26. The method according to claim 8, wherein the drying time is 1 to 10 hours.
27. The method of claim 8, wherein the drying is performed in an inert atmosphere.
28. The method according to claim 8, wherein the temperature of the reaction in step (1) is 30 to 80 ℃.
29. The method according to claim 8, wherein the reaction time in step (1) is 0.5 to 3 hours.
30. The process of claim 8, wherein the reaction in step (1) is carried out under stirring conditions.
31. The method according to claim 8, wherein the number of washing in step (1) is 2 to 5.
32. The method of claim 8, wherein the titanium source in step (2) comprises titanium tetrachloride.
33. The method of claim 8, wherein the electron donor comprises any one of or a combination of at least two of diethers, aromatic carboxylic acid diesters or siloxane compounds.
34. The method of claim 33, wherein the electron donor is gamma-chloropropyltriethoxysilane.
35. The method according to claim 8, wherein the mass ratio of the titanium source to the nano hydrotalcite is 10 to 16.
36. The method of claim 8, wherein the mass ratio of the electron donor to the nano hydrotalcite is 0.1-5:1.
37. The method of claim 8, wherein the temperature of the titanium bearing reaction is 20 to 80 ℃.
38. The method of claim 8, wherein the titanium bearing reaction time is 1 to 5 hours.
39. The method of claim 8, wherein the washed wash liquid is an alkane solvent.
40. The method of claim 39, wherein the wash solution is n-hexane.
41. The method according to claim 8, characterized in that it comprises the steps of:
(1) Mixing the dried nano hydrotalcite with the ignition loss reduced to 1-12%, a chemical activating agent and a solvent I, reacting at 30-80 ℃ for 0.5-3 h to obtain a pre-carrier, and cleaning the pre-carrier by using a solvent II to obtain a carrier;
wherein, mg in the nano hydrotalcite 6 Al 2 (OH) 16 CO 3 ·4H 2 The mass fraction of O is more than or equal to 95wt percent, and the nano waterThe initial ignition loss of the talc is 5-30%, the solvent I is a saturated hydrocarbon and/or ether compound with 4-20 carbon atoms, the solvent II is a saturated hydrocarbon and/or ether compound with 4-20 carbon atoms, the ratio of the chemical activator to the nano hydrotalcite is (0.1-0.5mol);
(2) Mixing the carrier and a titanium source, adding an electron donor, carrying out titanium-carrying reaction at 20-80 ℃ for 1-5 h, and washing to obtain a catalyst;
wherein the electron donor comprises one or the combination of at least two of diether, aromatic carboxylic diester or siloxane compounds, the mass ratio of the titanium source to the nano hydrotalcite is 10-16, and the mass ratio of the electron donor to the nano hydrotalcite is 0.1-5:1.
42. A process for the preparation of low-entanglement ultrahigh molecular weight polyethylene using the catalyst of any one of claims 1 to 7.
43. The method of claim 42, comprising the steps of: mixing solvent III, cocatalyst, catalyst and ethylene, and carrying out polymerization reaction to obtain the low-entanglement ultrahigh molecular weight polyethylene.
44. The method as claimed in claim 43, wherein the solvent III comprises a saturated hydrocarbon and/or an aromatic hydrocarbon having 4 to 10 carbon atoms.
45. The method according to claim 44, wherein the solvent III is n-hexane.
46. The method of claim 43, wherein the co-catalyst comprises any one of or a combination of at least two of an aluminum alkyl, an aluminum alkoxide, or an aluminum chloroalkyl.
47. The method of claim 46, wherein the alkyl aluminum has 1 to 10 carbon atoms.
48. The method of claim 46, wherein the aluminum alkyl is triethylaluminum.
49. The method of claim 46, wherein said aluminum alkoxide has 1 to 10 carbon atoms.
50. The method of claim 43, wherein the ratio of cocatalyst to solvent III is 0.001-0.01mol.
51. The method of claim 50, wherein the ratio of cocatalyst to solvent III is 0.001-0.005mol.
52. The process according to claim 43, wherein the ratio of catalyst to solvent III is 50 to 90mg.
53. The process of claim 43, wherein the polymerization temperature is from 20 to 90 ℃.
54. The process of claim 43, wherein the pressure of the polymerization reaction is 0.1 to 2MPa.
55. The process according to claim 43, wherein the polymerization time is from 0.5 to 10 hours.
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