Preparation method of metallocene catalyst mixture and method for preparing polyolefin

Abstract

The invention discloses a preparation method of a metallocene catalyst mixture, which comprises the following steps: coordinating a catalyst A with diethyl zinc at low temperature to form a novel catalyst D, mixing the novel catalyst D with a catalyst B, and carrying out olefin polymerization. The preparation steps are simple and easy to operate, and the generated new catalyst mixture shows high activity and strong copolymerization ability in the polymerization process of synthesizing ethylene and alpha-olefin, and has good processability and mechanical properties in the aspect of film processing.

Description

Technical Field

[0001] The present invention relates to the technical field of polymerization catalysts, and particularly to a preparation method of a metallocene catalyst mixture having high activity and strong copolymerization ability in the synthesis of ethylene and α-olefins. Background Art

[0002] Copolymers of ethylene and α-olefins are important polymer materials, which have the characteristics of low melting point, low crystallinity, low density, good flexibility and processability. The rapid development of polyolefins has been accompanied by continuous progress of olefin polymerization catalysts. Early copolymers of ethylene and α-olefins used Ziegler-Natta catalysts, and the polymer activity was very low. It was not until metallocene catalysts were discovered that, due to their ideal single active center, metallocene catalysts can change the electronegativity and spatial environment of the active center by changing their coordination groups, thereby controlling the microstructure and macroscopic performance of the polymer. As a new type of high-efficiency metallocene catalyst, the constrained geometry catalyst was first reported by DOW in patent EP0416815A2 in 1991 and applied to industrial production. The copolymers of ethylene and α-olefins obtained by its polymerization have the characteristics of long chain branching and narrow molecular weight distribution. However, most of this type of constrained geometry catalysts have the following problems: low activity, large amount of cocatalyst used, high cost, low polymer solid content, high energy consumption for recovery, high ash content in the polymer, poor hue or low transparency of the prepared polymer, and difficulty in film forming.

[0003] European Patent EP0420436A2 discloses a constrained geometry catalyst. The cocatalyst used in this patent is MAO. However, since MAO requires a high Al / Ti when used in olefin polymerization, this not only increases the cost of the polymer, but also makes the residual amount of Al in the polymerization product too high, thus limiting the application of this type of catalyst.

[0004] When using this constrained geometry catalyst in US Patent US5096867 for the polymerization of ethylene and α-olefins (1-hexene, 1-octene and 1-decene), the polymerization activity is low, only 10 7 g / mol of polymerization activity, the solid content in the polymerization reaction system is low, the solvent amount used in the system is large, and the solvent recovery amount is large, increasing the energy consumption of the device.

[0005] European Patent EP0418044A2 discloses a constrained geometry catalyst. The cocatalyst used in this patent is an organoboron compound. The organoboron compound with large steric hindrance (PBB) can increase the activity of the CGC catalyst, but the increased degree still cannot meet the industrial requirements, and it is extremely demanding for the device design specifications, which also makes it impossible to be fully applied in industry.

[0006] With the in-depth research of a large number of scientific researchers on metallocene catalysts, double metallocene catalysts have been reported more and more. For example, Chinese patents CN109957057B, CN1200007C, CN104892812A, and CN104023844A all involve the use of double metallocene catalysts to catalyze the synthesis of ethylene-α-olefin copolymers. However, for the ethylene-α-olefin polymers produced using this double metallocene catalyst, there are the following problems: the polymers obtained have poor processing performance. When the melt strength is high, during film processing, the quality has low hue transparency, and white spots are generated when forming the film. When the melt strength is low, the tensile strength is insufficient, it is not easy to form a film, and the barrier property is poor. In the polymer structure, the characteristics of the number, length, and relative molecular mass distribution of the branched chains will directly affect the product quality. The metallocene catalyst for synthesizing this type of polymer structure has become the main research direction. Especially with the increasing growth of this type of material in many fields, its processing performance in applications requires our attention. Summary of the Invention

[0007] The object of the present invention is to provide a preparation method of a metallocene catalyst mixture. The preparation steps of this type of metallocene catalyst mixture are simple and easy to operate. Using this type of metallocene catalyst mixture has high polymerization activity and strong copolymerization ability. When it is used to synthesize ethylene-α-olefin polymers, the polyolefin materials prepared have good processability and mechanical properties in film processing.

[0008] To achieve the above technical effects, the present invention adopts the following technical solutions:

[0009] A preparation method of a metallocene catalyst mixture is to mix a halogenated metallocene catalyst A and a coordination group to generate a new catalyst D, and then mix it with an alkylated metallocene catalyst B.

[0010] It includes the following steps:

[0011] (1) Dissolve catalyst A in solvent C sufficiently.

[0012] (2) Add the coordination group to the solution in step 1, and under low-temperature conditions, mix and stir to complete the coordination reaction to generate a new catalyst D. After the reaction ends, it is saturated and precipitated in an alkane solvent, and then filtered and dried.

[0013] (3) Mix the new catalyst D and catalyst B in proportion and dissolve them in a benign solvent to form a catalyst mixture.

[0014] Among them, the ligand structures of catalyst A and B metallocene catalysts are the same, and the metal center is mainly from Group ⅣB, which can be the same or different; the molar ratio of catalyst D to catalyst B is 1-5:100.

[0015] The alkylation types of catalyst B can be C1-20 alkyl, C2-10 alkenyl, C7-40 alkylaryl, C7-40 arylalkyl, C6-20 aryl, substituted or unsubstituted C1-20 alkylidene, substituted or unsubstituted amino, C2-20 alkylalkoxy or C7-40 arylalkoxy.

[0016] Among them, the coordinating group is diethylzinc.

[0017] The metallocene catalyst in the present invention, wherein the metallocene compound is represented by the following Chemical Formula 1:

[0018] Chemical Formula 1

[0019] [Cp 1 (R a ) p B 1 [Cp 2 (R b ) q MZ 1 2

[0020] Among them, in Chemical Formula 1, Cp 1 and Cp 2 are the same as or different from each other, and independently are one selected from the following groups: cyclopentadienyl, indenyl, 4,5,6,7-tetrahydro-1-indenyl, fluorenyl and 2,3,4,7,8,9,10,12-octahydro-1H-dibenzofluorene;

[0021] R a and R b are the same as or different from each other, and independently are C1-20 alkyl, C1-10 alkoxy, C7-20 aryloxy, C1-10 alkylamino, C7-20 arylamino, C7-20 arylalkyl, C7-20 alkylaryl, C2-20 alkenyl, C8-20 arylalkenyl or C2-10 alkynyl;

[0022] p and q are independent of each other, and the value ranges are 0≤p,q≤16, and both p and q are integers;

[0023] B 1 is one selected from the following groups: a group of carbon, silicon and germanium or a combination of different substitutions thereof, and the substituents can be C1-20 alkyl, C2-10 alkenyl, C7-40 alkylaryl, C7-40 arylalkyl, C6-20 aryl, C7-40 arylalkoxy, C7-40 alkoxyaryl, C1-20 aminoalkyl or C7-40 aminoaryl;

[0024] M is a metal of Group IVB;

[0025] Z in the corresponding formula of catalyst A 1is a halogen atom, and Z in catalyst B corresponds to the formula 1 is a C1-20 alkyl group, a C2-10 alkenyl group, a C7-40 alkylaryl group, a C7-40 arylalkyl group, a C6-20 aryl group, a substituted or unsubstituted C1-20 alkylidene group, a substituted or unsubstituted amino group, a C2-20 alkylalkoxy group or a C7-40 arylalkoxy group.

[0026] The metallocene catalyst represented by Chemical Formula 1 can be a compound represented by one of the following structural formulas, but is not limited to the following. For example,

[0027]

[0028]

[0029] In the present invention, the solvent C in Step 1 is represented by the following Structural Formula 2:

[0030] Structural Formula 2

[0031]

[0032] Among them, X in Structural Formula 2 is a halogen atom, the value range of n is 0 to 5, and n is an integer; chlorobenzene, benzyl chloride, and o-dichlorobenzyl are preferred.

[0033] In the preparation method of the metallocene catalyst mixture of the present invention, the molar concentration of catalyst A in Step (1) is 0.1 to 10 μmol / ml, preferably 0.1 to 1 μmol / ml.

[0034] In the preparation method of the metallocene catalyst mixture of the present invention, the content of the coordination group is 1 to 1.2 times the molar amount of catalyst A.

[0035] In the preparation method of the metallocene catalyst mixture of the present invention, the stirring time in Step (2) is 5 to 60 min, preferably 10 to 30 min; the stirring temperature is -20 to 10 °C, preferably -10 to 0 °C.

[0036] In the preparation method of the metallocene catalyst mixture of the present invention, the alkane solvent in Step (2) is at least one of a lipid hydrocarbon and an alicyclic hydrocarbon; one of n-hexane, n-heptane, and cyclohexane is preferred.

[0037] In the preparation method of the metallocene catalyst mixture of the present invention, the addition amount of the alkane solvent in Step (2) is 1 to 20 times the volume of its solution, preferably 3 to 10 times.

[0038] The method for preparing the metallocene catalyst mixture according to the present invention, wherein the benign solvent in step (3) is at least one of aromatic hydrocarbons and halogenated hydrocarbons; preferably one of toluene or xylene.

[0039] The method for preparing the metallocene catalyst mixture according to the present invention, wherein the configured concentration of the benign solvent added in step (3) is 0.5 - 5 ml / umol, preferably 1 - 2 ml / umol.

[0040] Among them, the newly generated catalyst D has the following important functional characteristics:

[0041] (1) After coordination with diethylzinc, in the structure of the newly generated catalyst D, due to the relatively low electronegativity of zinc, diethylzinc can effectively provide the electrons in the ethyl group to the active metal center, increasing the electron density of the active metal center, so that it still has high stability under high temperature conditions;

[0042] (2) Diethylzinc has the characteristics of chain transfer and chain shuttling. By coordinating with the newly generated catalyst D, the long chain after β-H elimination can be rapidly transferred during the polymerization process. This long chain segment is re-inserted into the active center as a new polymerization unit, and the resulting polymer can achieve the structural characteristics of high degree of branching and long branches;

[0043] (3) In the prepared metallocene catalyst mixture, since the amount of the newly synthesized catalyst D added is small, it will not cause self-polymerization, ensuring that the molecular weight distribution of the resulting polymer does not broaden and the molecular weight does not decrease significantly;

[0044] (4) Metal zinc has a relatively low degree of ionization compared to aluminum. The occurrence of the oxidation-reduction reaction between these two metals mostly aggregates at the active metal center of catalyst D, making it easy for olefin monomers to undergo coordination insertion, thus increasing the catalytic activity;

[0045] The method for preparing polyolefins, using the metallocene catalyst mixture according to the present invention, the method for preparing ethylene and α-olefin polymers includes the following steps:

[0046] a. Prepare the above-mentioned metallocene catalyst mixture under an inert gas;

[0047] b. Add the cocatalyst to solvent E containing α-olefin monomers, then fill the system with high-pressure ethylene, stir and heat to the reaction temperature;

[0048] c. Add the metallocene catalyst mixture in step a to the reaction system to carry out the polymerization reaction. After a period of time, quench to obtain the polymer.

[0049] The method for preparing polyolefins according to the present invention, wherein the cocatalyst in step b contains the compound represented by the following chemical formula 3;

[0050] Chemical formula 3

[0051] -[Al(R c )-O] n -

[0052] Among them, in Chemical formula 3, R c is a halogen, a C1-10 hydrocarbon group or a C1-10 hydrocarbon group substituted by a halogen; where n is an integer ≥ 2.

[0053] The compound represented by Chemical formula 3 can be one of methylaluminoxane, ethylaluminoxane, isobutylaluminoxane, butylaluminoxane, octylaluminoxane;

[0054] Further contains one or more of the compounds represented by the following Chemical formula 4 or Chemical formula 5:

[0055] Chemical formula 4

[0056] B 2 (R d )3

[0057] Among them, in Chemical formula 4, R d is a halogen, a C1-20 hydrocarbon group or a C1-20 hydrocarbon group substituted by a halogen; B 2 can be aluminum or boron;

[0058] Examples of the compound represented by Chemical formula 4 can include trimethylaluminum, triethylaluminum, triisobutylaluminum, tripropylaluminum, tributylaluminum, monomethyldichloride aluminum, dimethylchloride aluminum, triisopropylaluminum, tri-sec-butylaluminum, tripentylaluminum, triisopentylaluminum, trihexylaluminum, trioctylaluminum, ethyldimethylaluminum, methyldiethylaluminum, triphenylaluminum, tri-p-tolylaluminum, dimethoxymethylaluminum, monomethoxydimethylaluminum, dimethylethylaluminum, trimethylboron, triethylboron, tripropylboron, tributylboron, triisobutylboron, etc., preferably one of trimethylaluminum, triethylaluminum, triisobutylaluminum and trioctylaluminum;

[0059] Chemical formula 5

[0060] [D-H] + [Z 2 T4]- or [D] + [Z 2 T4] -

[0061] Among them, in Chemical formula 5, D is neutral or cationic;

[0062] H is a hydrogen atom

[0063] Z 2 is a Group IIIA atom

[0064] T is an aryl group having 6 to 20 carbon atoms or an alkyl group having 1 to 20 carbon atoms, wherein the hydrogen atoms may or may not be substituted by a halogen, a hydrocarbon group having 1 to 20 carbon atoms, an alkoxy group or a phenoxy group.

[0065] Examples of the compound represented by Chemical Formula 5 may include triethylammonium tetrakis(phenyl)borate, tributylammonium tetrakis(phenyl)borate, trimethylammonium tetrakis(phenyl)borate, tripropylammonium tetrakis(phenyl)borate, trimethylammonium tetrakis(p-tolyl)borate, trimethylammonium tetrakis(o,p-dimethylphenyl)borate, tributylammonium tetrakis(p-trifluoromethylphenyl)borate, trimethylaluminum tetrakis(p-trifluoromethylphenyl)borate, tributylammonium tetrakis(pentafluorophenyl)borate, N,N-diethylanilinium tetrakis(phenyl)borate, N,N-dimethylanilinium tetrakis(phenyl)borate, diethylammonium tetrakis(pentafluorophenyl)borate, triphenylphosphonium tetrakis(phenyl)borate, trimethylphosphonium tetrakis(phenyl)borate, triethylammonium tetrakis(phenyl)aluminate, tributylammonium tetrakis(phenyl)aluminate, trimethylammonium tetrakis(phenyl)aluminate, tripropylammonium tetrakis(phenyl)aluminate, trimethylammonium tetrakis(p-tolyl)aluminate, tripropylammonium tetrakis(p-tolyl)aluminate, triethylammonium tetrakis(o,p-dimethylphenyl)aluminate, tributylammonium tetrakis(p-trifluoromethylphenyl)aluminate, trimethylammonium tetrakis(p-trifluoromethylphenyl)aluminate, tributylammonium tetrakis(pentafluorophenyl)aluminate, N,N-dimethylanilinium tetrakis(phenyl)aluminate, N,N-diethylanilinium tetrakis(phenyl)aluminate, N,N-diethylanilinium tetrakis(pentafluorophenyl)aluminate, diethylammonium tetrakis(pentafluorophenyl)aluminate, triphenylphosphonium tetrakis(phenyl)aluminate, trimethylphosphonium (phenyl)aluminate, tripropylammonium tetrakis(p-tolyl)borate, triethylammonium tetrakis(o,p-dimethylphenyl)borate, trimethylphosphonium tetrakis(phenyl)aluminate, tripropylammonium tetrakis(p-tolyl)borate, triethylammonium tetrakis(o,p-dimethylphenyl)borate, tributylammonium tetrakis(p-trifluoromethylphenyl)borate, triphenylcarbenium tetrakis(p-trifluoromethylphenyl)borate, triphenylcarbenium tetrakis(pentafluorophenyl)borate, triphenylcarbenium tetrakis(octafluoronaphthyl)borate, triethylammonium tetrakis(octafluoronaphthyl)borate, N,N-dimethylanilinium tetrakis(octafluoronaphthyl)borate, N,N-diethylanilinium tetrakis(octafluoronaphthyl)borate, etc.

[0066] In the present invention, the molar ratio of the co-catalysts of Chemical Formula 4 and Chemical Formula 5 used to the total molar amount of Catalyst A and Catalyst B is 1 to 1000:1. The co-catalysts 4 and 5 in the above ratio act together with the main catalyst to optimize the activity and control the structure of the polymer; if in excess, the effect may be significantly reduced and the desired polymer cannot be obtained.

[0067] In the method for preparing polyolefins according to the present invention, the solvent E in step b is a hydrocarbon solvent, including at least one of aliphatic hydrocarbons, alicyclic hydrocarbons, aromatic hydrocarbons, and halogenated hydrocarbons, preferably one of mixed saturated alkanes and methylcyclohexane.

[0068] The method for preparing polyolefin according to the present invention, the α-olefin in step b can be one or more of propylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-heptene, 1-octene, 1-decene, 1-undecene and 1-dodecene.

[0069] The method for preparing polyolefin according to the present invention, the ethylene pressure is 5-50 bar, preferably 20-40 bar.

[0070] The method for preparing polyolefin according to the present invention, the polymerization temperature is 70-200 °C, preferably 100-160 °C.

[0071] The method for preparing polyolefin according to the present invention, the polymerization time is 1-120 min, preferably 5-30 min;

[0072] The method for preparing polyolefin according to the present invention, the quenching agent is at least one of methanol, ethanol, ethylene glycol, 1,2-propanediol, 1,3-propanediol and glycerol, preferably ethanol and ethylene glycol; the dosage can be equal to the volume of the polymerization reaction solution.

[0073] In particular, the metallocene catalyst mixture of the present invention exhibits excellent activity, and by using the preparation synthesis method of the present invention, polyolefins with high insertion rate, narrow molecular weight distribution and excellent mechanical properties (high melt flow rate ratio) can be obtained, and the polymers have excellent processability and excellent physical properties. Detailed implementation mode

[0074] In order to better understand the present invention, preferred embodiments will be presented. However, the following embodiments are only proposed for understanding the present invention, and the scope of the present invention is not limited thereto.

[0075] The sources of main raw materials and equipment in the examples and comparative examples of the present invention are as follows. If not otherwise specified, others are obtained from ordinary commercial channels:

[0076] Experimental raw materials

[0077] Ethylene was purchased from Tianjin Saimet Chemical Technology Co., Ltd.;

[0078] Isopar E alkane solvent was purchased from ExxonMobil;

[0079] Toluene was purchased from Aladdin, with a purity of 99%;

[0080] Methylaluminoxane (MAO) was purchased from Nouryon, with an aluminum content of 7 wt%;

[0081] Modified methylaluminoxane (MMAO) was purchased from Nouryon, with an aluminum content of 7 wt%;

[0082] The hexane solution of triisobutylaluminum was purchased from Xiya Company with a concentration of 1 mol / L;

[0083] Triphenylmethyltetrakis(pentafluorophenyl)borate was purchased from Energy Chemical with a purity of 98%;

[0084] N,N-Dimethylanilinium tetrakis(pentafluorophenyl)borate was purchased from Energy Chemical with a purity of 98%;

[0085] The hexane solution of diethylzinc was purchased from Xiya Company with a concentration of 1 mol / L;

[0086] 1-Octene was purchased from Aladdin with a purity of 98%;

[0087] 4A molecular sieve (3 - 4 mm, 0.12 - 0.16 in) diameter spheres were purchased from Acros Company;

[0088] 5A molecular sieve (3 - 4 mm, 0.12 - 0.16 in) diameter spheres were purchased from Acros Company;

[0089] 13X molecular sieve (3 - 4 mm, 0.12 - 0.16 in) diameter spheres were purchased from Acros Company;

[0090] The catalysts of Formulas 6, 7, 8, 9 were purchased from Jiangsu Synchrotron Catalyst Co., Ltd.;

[0091] The catalysts of Formulas 10, 11 were purchased from Alfa Chemistry;

[0092] The catalysts of Formulas 12, 13, 14, 15 were purchased from Yuanfeng Technology Co., Ltd.;

[0093] The catalysts of Formulas 16, 17 were purchased from Jiangsu Synchrotron Catalyst Co., Ltd.

[0094] Purification method

[0095] High-pressure ethylene was passed through a gas purification system to remove the water and oxygen in the ethylene before it could be used;

[0096] Isopar E alkane solvent was bubbled with high-purity nitrogen for 6 hours to remove the oxygen in the solvent, and then purified by circulating through the purification system for 48 hours. After testing that the water content was less than 10 ppm, it could be used;

[0097] 1-Octene was bubbled with high-purity nitrogen for 6 hours to remove the oxygen in the solvent, and then purified by circulating through the purification system for 48 hours. After testing that the water content was less than 10 ppm, it could be used;

[0098] Chlorobenzene, benzyl chloride, and o-dichlorobenzene were soaked in 4A molecular sieves that had been baked at high temperature for 48 hours. After testing that the water content was less than 10 ppm, they could be used;

[0099] After the 4A molecular sieve soaked in toluene is baked at high temperature for 48 hours, it can be used only after the measured moisture is less than 10 ppm.

[0100] Experimental equipment

[0101] Gas purification system: The device contains two 5L volume purification columns. One column is filled with 5A molecular sieve (3 - 4mm, 0.12 - 0.16in) diameter balls, and the other is filled with 13X molecular sieve (3 - 4mm, 0.12 - 0.16in) diameter ball packing. The gas flow rate is 1L / min;

[0102] Solvent purification system: The device contains two 4L volume purification columns. One column is filled with 4A molecular sieve (3 - 4mm, 0.12 - 0.16in) diameter balls, and the other is filled with 13X molecular sieve (3 - 4mm, 0.12 - 0.16in) diameter ball packing. The solvent circulation flow rate is 2L / min;

[0103] 2L reactor: This device is a polymerization equipment with functions such as rapid heating and cooling;

[0104] Metering pump: Solvent metering and weighing equipment with a flow rate of 300ml / min;

[0105] Balance: The precision is 0.1mg

[0106] Anhydrous and anaerobic glove box: Prepare the catalyst solution and provide an environment isolated from water and oxygen.

[0107] Preparations before the experiment

[0108] Measure 1ml of 1mol / L triisobutylaluminum hexane solvent and drop it into 10ml of purified Isopar E solvent, dilute and shake well for standby;

[0109] Measure 0.1ml of 1mol / L diethylzinc hexane solvent and drop it into 100ml of purified Isopar E solvent, dilute and shake well for standby.

[0110] Example 1

[0111] Catalyst preparation method:

[0112] Weigh 1.8umol of the catalyst of Chemical Formula 6 below into a 50ml Schlenk flask, add 18ml of chlorobenzene solvent dried by 4A molecular sieve, fully dissolve it, then drop 2ml of the diethylzinc dilution into the above solution, add a magnetic stirrer, stir at 0°C for 5 minutes. After the reaction ends, add 30ml of n - hexane, and new catalyst 6' crystallizes out, then filter and dry.

[0113] NMR characterization: H 1NMR (400 MHz, CDCl3) δ 0.87 (3H, t), 1.38 (2H, dd), 6.37 - 6.46 (8H, dd), 7.24 - 7.35 (10H, dd)

[0114] Weigh 0.18 μmol of the above-mentioned new catalyst 6' and 3.6 μmol of the catalyst of Reaction Formula 7, add them to a 20 ml glass sample bottle, add 5 ml of toluene solvent after drying with 4A molecular sieve, and set aside.

[0115]

[0116] Polymerization method:

[0117] Add the prepared catalyst above to the spare small bin in the reaction kettle, keep 3.5 MPa of nitrogen gas for standby. Use a metering pump to add 500 mL of Isoper E and 300 mL of 1-octene solution to a 2 L stainless steel reaction kettle, add 2 mL of methylaluminoxane (MAO), introduce ethylene and keep the pressure at 3 MPa, start stirring and heat up to 100 °C, then add it into the kettle, react at 100 °C for 10 min. After the reaction is completed, release the pressure of the system, replace it with nitrogen three times, discharge the polymerization liquid into a beaker containing 500 ml of ethanol, wait for the polymer to precipitate, and filter and dry.

[0118] Example 2

[0119] Catalyst preparation method:

[0120] Weigh 3.2 μmol of the catalyst of Reaction Formula 8 below into a 50 ml Schlenk flask, add 3.2 ml of chlorobenzene solvent after drying with 4A molecular sieve, fully dissolve it, then drop 3.5 ml of diethylzinc dilution solution into the above solution, add a magnetic stir bar, stir at -10 °C for 30 min. After the reaction is completed, add 30 ml of n-hexane, and new catalyst 8' will precipitate out. Filter and dry.

[0121] NMR characterization: H 1 NMR (400 MHz, CDCl3) δ 0.88 (3H, t), 1.39 (2H, dd), 5.84 (2H, d) 6.42 - 6.51 (6H, dd), 7.27 - 7.37 (10H, dd), 7.82 (2H, d)

[0122] Weigh 0.12 μmol of the above-mentioned new catalyst 8' and 2.4 μmol of the catalyst of Reaction Formula 9, add them to a 20 ml glass sample bottle, add 5 ml of toluene solvent after drying with 4A molecular sieve, and set aside.

[0123]

[0124] Polymerization method:

[0125] Add the prepared catalyst above into the spare small bin of the reactor, keep nitrogen at 3.5 MPa for standby. Use a metering pump to add 520 mL of Isoper E and 280 mL of 1-octene solution into a 2-L stainless-steel reactor, add 1.8 mL of modified methylaluminoxane (MMAO), introduce ethylene and keep the pressure at 3 MPa, start stirring and heat up to 100 °C, then add it into the reactor. React at 100 °C for 10 min. After the reaction is completed, relieve the pressure of the system, replace it with nitrogen three times, discharge the polymerization liquid into a beaker containing 500 mL of ethanol, wait for the polymer to precipitate, and filter and dry it.

[0126] Example 3

[0127] Catalyst preparation method:

[0128] Weigh 1.8 μmol of the catalyst of Reaction Formula 10 below into a 50-mL Schlenk flask, add 5 mL of chlorobenzene solvent after drying with 4A molecular sieve. After fully dissolving, drop 2 mL of diethylzinc dilution into the above solution, add a magnetic stirrer, stir at -10 °C for 30 min. After the reaction is completed, add 30 mL of n-hexane, and new catalyst 10' crystallizes out, then filter and dry it.

[0129] NMR characterization: H 1 NMR (400 MHz, CDCl3) δ 0.91 (3H, t), 1.42 (2H, dd), 5.83 (2H, t) 6.36 - 6.52 (4H, m), 7.04 (2H, ddd), 7.29 - 7.42 (4H, m), 7.46 (2H, td), 7.55 - 7.68 (2H, m), 7.84 - 8.03 (4H, m), 8.23 (2H, d)

[0130] Weigh 0.18 μmol of the above new catalyst 10' and 3.6 μmol of the catalyst of Reaction Formula 11, add them into a 20-mL glass sample bottle, add 5 mL of toluene solvent after drying with 4A molecular sieve, and set aside.

[0131]

[0132] Polymerization method:

[0133] Add the catalyst prepared above to the spare small bin of the reaction kettle, keep nitrogen at 3.5 MPa for standby. Use a metering pump to add 510 mL of Isoper E and 290 mL of 1-octene solution to a 2-L stainless steel reaction kettle. Add 1.8 mL of modified methylaluminoxane (MMAO), introduce ethylene and keep the pressure at 3 MPa. Start stirring and heat up to 100 °C, then add it into the kettle. React at 100 °C for 10 min. After the reaction is completed, relieve the pressure of the system and replace it with nitrogen three times. Discharge the polymerization liquid into a beaker containing 500 ml of ethanol, wait for the polymer to precipitate, and filter and dry it.

[0134] Example 4

[0135] Catalyst preparation method:

[0136] Weigh 1.8 μmol of the catalyst of Reaction Formula 12 below into a 50-ml Schlenk flask, add 10 ml of chlorobenzene solvent after drying with 4A molecular sieve. After fully dissolving, drop 2 ml of diethylzinc dilution into the above solution, add a magnetic stir bar, and stir at -10 °C for 10 min. After the reaction is completed, add 60 ml of n-hexane, and new catalyst 12′ will precipitate out. Filter and dry it.

[0137] NMR characterization: H 1 NMR(400 MHz, CDCl3) δ 0.91(3H, t), 1.35(18H, m), 1.42(2H, dd), 5.83(2H, t), 6.34 - 6.50(4H, m), 7.04(2H, ddd), 7.29 - 7.42(4H, m), 7.55 - 7.68(2H, m), 7.84 - 8.03(4H, m), 8.23(2H, d)

[0138] Weigh 0.18 μmol of the above new catalyst 12′ and 3.6 μmol of the catalyst of Reaction Formula 13, add them to a 20-ml glass sample bottle, and add 7 ml of toluene solvent after drying with 4A molecular sieve for standby.

[0139]

[0140] Polymerization method:

[0141] Add the catalyst prepared above to the spare small bin of the reactor, keep nitrogen at 3.5 MPa for standby. Use a metering pump to add 510 mL of Isoper E and 290 mL of 1-octene solution to a 2-L stainless-steel reactor, add 7 mL of diluted triisobutylaluminum and 7.9 mg of triphenylmethyltetrakis(pentafluorophenyl)borate. Introduce ethylene and keep the pressure at 3 MPa. Start stirring and heat up to 120 °C, then add it to the reactor. React at 120 °C for 20 min. After the reaction is completed, relieve the pressure of the system and displace it with nitrogen three times. Drain the polymerization liquid into a beaker containing 500 ml of ethanol, wait for the polymer to precipitate, and filter and dry it.

[0142] Example 5

[0143] Catalyst preparation method:

[0144] Weigh 2 umol of the catalyst of Reaction Formula 14 below into a 50-ml Schlenk flask, add 10 ml of chlorobenzene solvent after drying with 4A molecular sieve. After fully dissolving, drop 2.8 ml of diluted diethylzinc solution into the above solution, add a magnetic stirrer, and stir at 0 °C for 30 min. After the reaction is completed, add 50 ml of n-hexane, and a new catalyst 14′ will precipitate out. Filter and dry it.

[0145] NMR characterization: H 1 NMR(400MHz,CDCl3)δ0.91(3H,t),1.35(18H,m)1.42(2H,dd),2.34(6H,dd),5.81(2H,t),6.38 - 6.64(4H,m),7.04(2H,ddd),7.29 - 7.42(2H,m),7.55 - 7.68(2H,m),7.84 - 8.03(4H,m),8.23(2H,d)

[0146] Weigh 0.08 umol of the above new catalyst 14′ and 1.6 umol of the catalyst of Reaction Formula 15, add them to a 20-ml glass sample bottle, and add 2 ml of toluene solvent after drying with 4A molecular sieve for standby.

[0147]

[0148] Polymerization method:

[0149] Add the catalyst prepared above to the spare small bin of the reaction kettle, keep nitrogen at 3.5 MPa for standby. Use a metering pump to add 510 mL of Isoper E and 290 mL of 1-octene solution to a 2-L stainless-steel reaction kettle. Add 4.8 mL of diluted triisobutylaluminum and 3.6 mg of N,N-dimethylanilinium tetrakis(pentafluorophenyl)borate. Introduce ethylene and keep the pressure at 3 MPa. Start stirring and heat up to 130 °C, then add it into the kettle. React at 130 °C for 10 min. After the reaction is completed, relieve the pressure of the system and replace it with nitrogen three times. Drain the polymerization solution into a beaker containing 500 ml of ethanol, wait for the polymer to precipitate, and filter and dry it.

[0150] Example 6

[0151] Catalyst preparation method:

[0152] Weigh 1.8 μmol of the catalyst of Reaction Formula 16 below into a 50-ml Schlenk flask, add 18 ml of chlorobenzene solvent after drying with 4A molecular sieve. After fully dissolving, drop 2.2 ml of diluted diethylzinc solution into the above solution, add a magnetic stirrer, and stir at -10 °C for 30 min. After the reaction is completed, add 50 ml of n-hexane, and new catalyst 16′ will precipitate out. Filter and dry it.

[0153] NMR characterization: H 1 NMR(400MHz,CDCl3)δ0.91-1.07(15H,sd),1.35-1.42(14H,dd),1.61(8H,m),5.81-6.21(4H,s),6.42(2H,s),6.97-7.7(8H,dd),8.1(2H,m),8.42(2H,d)

[0154] Weigh 0.18 μmol of the above new catalyst 16′ and 3.6 μmol of the catalyst of Reaction Formula 17, add them to a 20-ml glass sample bottle, and add 5 ml of toluene solvent after drying with 4A molecular sieve for standby.

[0155]

[0156] Polymerization method:

[0157] Add the above-prepared catalyst to the spare small bin of the reaction kettle, keep nitrogen at 3.5 MPa in reserve, use a metering pump to add 510 mL of Isoper E and 290 mL of 1-octene solution to a 2-L stainless steel reaction kettle, add 2 mL of modified methylaluminoxane (MMAO), introduce ethylene and maintain the pressure at 3 MPa, start stirring and heat up to 140 °C, then add it into the kettle, react at 140 °C for 10 min. After the reaction is completed, release the pressure of the system, displace with nitrogen three times, discharge the polymerization solution into a beaker containing 500 ml of ethanol, wait for the polymer to precipitate, filter and dry.

[0158] Compared with Examples 1-6, Comparative Examples 1-6 are directly two catalyst mixtures without synthesizing a new catalyst by coordinating diethylzinc; compared with Examples 1-6, Comparative Examples 7-12 are new catalysts synthesized by diethylzinc in a n-hexane solution at room temperature.

[0159] Evaluation method:

[0160] (1) Catalytic activity: Calculated as the ratio of the weight (g / mol) of the polymer produced per mole amount (mol) of the catalyst used per unit time (h).

[0161] (2) Molecular weight, molecular weight distribution (MWD) and comonomer content (wt%) of the polymer: By using the method of high-temperature GPC-infrared coupling, measure the weight-average molecular weight (Mw) and number-average molecular weight (Mn) of the polymer, and calculate the molecular weight distribution (MWD) by dividing the weight-average molecular weight by the number-average molecular weight. The test temperature is 150 °C, polystyrene is used as the standard sample, trichlorobenzene is used as the solvent, and the flow rate is 1.0 ml / min.

[0162] (3) MI2.16 of the polymer: Measured according to ASTM D 1238 at 190 °C under a load of 2.16 kg and expressed as the weight (g) of the molten polymer within 10 minutes.

[0163] (4) MI10 of the polymer: Measured according to ASTM D 1238 at 190 °C under a load of 10 kg and expressed as the weight (g) of the molten polymer within 10 minutes.

[0164] (5) Melt flow rate ratio (MFRR) of the polymer: Expressed as the value of MI10 / MI2.16 measured according to ASTM D 1238.

[0165] For the polymers of the above examples and comparative examples, the properties were evaluated as follows, and the results are shown in Table 1 below.

[0166]

[0167]

[0168] Continued table:

[0169] Comparative Example 2 5.5 8.7 2.64 19 2.2 16.9 7.7 Comparative Example 3 6.2 10.1 2.61 27 1.8 14 7.9 Comparative Example 4 8.5 11.8 2.55 25 0.9 7.2 8.1 Comparative Example 5 9.2 12.7 2.91 26 0.5 4.1 8.2 Comparative Example 6 13.8 11.3 2.78 24 1.0 8.9 8.9 Comparative Example 7 5.3 6.9 3.05 22 2.9 26.3 9.1 Comparative Example 8 6.2 7.3 3.12 26 2.5 22.5 9.0 Comparative Example 9 7.9 8.2 2.91 23 2.3 19.5 8.5 Comparative Example 10 9.9 9.5 2.87 27 1.9 17.6 9.3 Comparative Example 11 8.6 8.8 2.97 24 2.4 23.5 9.8 Comparative Example 12 11.5 8.3 2.84 25 2.5 24.7 9.9

[0170] As can be seen from the above table, compared with Comparative Examples 1-12, the metallocene catalyst mixture after successful coordination of diethylzinc has high polymerization activity and copolymerization ability, and the obtained polyolefin products also have a high melt flow rate ratio. Compared with the products obtained by traditional methods, they have more excellent processability and mechanical properties.

Claims

1. A method for preparing a metallocene catalyst mixture, characterized in that, It is obtained by mixing a halogenated metallocene catalyst A and a coordination group to form a new catalyst D, and then mixing it with an alkylated metallocene catalyst B; it includes the following steps: (1) Fully dissolve catalyst A in solvent C; (2) Add the coordination group to the solution in step 1, mix and stir under low-temperature conditions to complete the coordination reaction to form a new catalyst D. After the reaction is completed, it is saturated and precipitated in an alkane solvent, and then filtered and dried; (3) Mix the new catalyst D and catalyst B in proportion and dissolve them in a benign solvent to form a catalyst mixture; Among them, the ligand structures of catalyst A and B are the same, and the metal centers are mainly from Group ⅣB, which can be the same or different; the molar ratio of catalyst D to catalyst B is 1-5:100; The said coordination group is diethyl zinc.

2. The preparation method according to claim 1, wherein, The said metallocene compound is represented by the following Chemical Formula 1: Chemical Formula 1 [Cp 1 (R a ) p B 1 [Cp 2 (R b ) q MZ 1 2 Among them, in Chemical Formula 1, Cp 1 and Cp 2 are the same as or different from each other and are each independently one selected from the following groups: cyclopentadienyl, indenyl, 4,5,6,7-tetrahydro-1-indenyl, fluorenyl, and 2,3,4,7,8,9,10,12-octahydro-1H-dibenzofluorene; R a and R b are the same as or different from each other and are independently C1-20 alkyl, C1-10 alkoxy, C7-20 aryloxy, C1-10 alkylamino, C7-20 arylamino, C7-20 arylalkyl, C7-20 alkylaryl, C2-20 alkenyl, C8-20 arylalkenyl or C2-10 alkynyl; p and q are independent of each other, and the value ranges are 0≤p,q≤16, and both p and q are integers; B 1 One selected from the following groups: a group of carbon, silicon, and germanium or a combination of different substitutions thereof, and the substituent may be a C1-20 alkyl group, a C2-10 alkenyl group, a C7-40 alkylaryl group, a C7-40 arylalkyl group, a C6-20 aryl group, a C7-40 arylalkoxy group, a C7-40 alkoxyaryl group, a C1-20 aminoalkyl group, or a C7-40 aminoaryl group; M is a metal of Group ⅣB; Z in the formula corresponding to Catalyst A 1 is a halogen atom, and Z in the formula corresponding to Catalyst B 1 is a C1-20 alkyl group, C2-10 alkenyl group, C7-40 alkylaryl group, C7-40 arylalkyl group, C6-20 aryl group, substituted or unsubstituted C1-20 alkylidene group, substituted or unsubstituted amino group, C2-20 alkylalkoxy group or C7-40 arylalkoxy group.

3. The preparation method according to claim 1 or 2, characterized in that, The solvent C in the said step (1) is represented by the following Structural Formula 2: Structural Formula 2 Among them, X in Structural Formula 2 is a halogen atom, and the value range of n is 0-5, and n is an integer.

4. The preparation method according to any one of claims 1 to 3, characterized in that, The molar concentration of catalyst A in the said step (1) is 0.1-10 umol / ml, preferably 0.1-1 umol / ml.

5. The preparation method according to any one of claims 1-4, characterized in that, The content of the said coordination group is 1-1.2 times the molar amount of catalyst A.

6. The preparation method according to any one of claims 1-5, characterized in that, The stirring time in the said step (2) is 5-60 min, preferably 10-30 min; the stirring temperature is -20-10℃, preferably -10-0℃.

7. The preparation method according to any one of claims 1-6, characterized in that, The alkane solvent in the said step (2) is at least one of aliphatic hydrocarbons and alicyclic hydrocarbons, preferably one or more of n-hexane, n-heptane and cyclohexane. The addition amount of the alkane solvent in the said step (2) is 1-20 times the volume of the solution in step (1), preferably 3-10 times.

8. The preparation method according to any one of claims 1-7, characterized in that, The benign solvent in the said step (3) is at least one of aromatic hydrocarbons and halogenated hydrocarbons; preferably toluene or xylene. The added concentration of the benign solvent in the said step (3) is 0.5-5 ml / umol, preferably 1-2 ml / umol.

9. A method for preparing polyolefins, characterized in that, It includes the following steps: a. Prepare the metallocene catalyst mixture prepared by the preparation method described in any one of claims 1-8 under an inert gas; b. Add a cocatalyst to solvent E containing an α-olefin monomer, and then fill the system with high-pressure ethylene, stir and heat to the reaction temperature; c. Add the metallocene catalyst mixture in step a to the reaction system. After the polymerization reaction, quench to obtain a polymer.

10. The method according to claim 9, characterized in that, The cocatalyst in the said step b contains a compound represented by the following Chemical Formula 3; Chemical Formula 3 -[Al(R c )-O] n - Among them, in Chemical Formula 3, R c is a halogen, a C1-C10 hydrocarbon group or a C1-C10 hydrocarbon group substituted by a halogen; where n is an integer ≥ 2. It further contains one or more compounds selected from the compounds represented by the following Chemical Formula 4 or Chemical Formula 5: Chemical Formula 4 B 2 (R d )3 Among them, in Chemical Formula 4, R d is a halogen, a C1-C20 hydrocarbon group, or a C1-C20 hydrocarbon group substituted by a halogen; B 2 is aluminum or boron; Chemical Formula 5 [D-H] + [Z 2 T4] - Or [D] + [Z 2 T4] - Among them, in Chemical Formula 5, D is neutral or cationic; H is a hydrogen atom Z 2 is a Group IIIA atom T is an aryl group with 6-20 carbon atoms or an alkyl group with 1-20 carbon atoms, and the hydrogen atom can be substituted or unsubstituted by a halogen, a hydrocarbon group with 1-20 carbon atoms, an alkoxy group or a phenoxy group.

11. According to the preparation method described in claim 10, the solvent E in step b is a hydrocarbon solvent, including at least one of aliphatic hydrocarbons, alicyclic hydrocarbons, aromatic hydrocarbons, and halogenated hydrocarbons; and / or, the α-olefin in step b is one or more of propylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-heptene, 1-octene, 1-decene, 1-undecene, and 1-dodecene.

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