Metallocene catalyst for preparing a high molecular weight polyolefin and a preparation method thereof

Abstract

The present invention relates to a metallocene compound having novel structure which can provide various selectivity and activity to polyolefin copolymers, a preparation method thereof, and a preparation method of polyolefin using the metallocene compound.

Claims

1. A compound represented by the following structure: ##STR00006##

2. A catalyst for olefin polymerization, comprising the compound according to claim 1.

3. The catalyst for olefin polymerization according to claim 2, which is supported on at least one carrier selected from the group consisting of silica, silica-alumina and silica-magnesia.

4. A method for preparing polyolefin, comprising the step of polymerizing at least one olefinic monomer in the presence of the catalyst according to claim 2.

5. The method according to claim 4, wherein the olefinic monomer is at least one monomer selected from the group consisting of ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicosene, and a mixture thereof.

Description

DETAILED DESCRIPTION OF THE EMBODIMENT

(1) Hereinafter, the present invention provides preferable examples for illuminating the present invention. However, following examples are only for understanding the present invention, and the range of the present invention is not limited to or by them.

Example

(2) ##STR00004##

Step 1) Preparation of (6-t-butoxyhexyl)(methyl)-bis(2-methyl-4-tert-butyl-phenylindenyl)silane

(3) After dissolving 2-methyl-4-tert-butylphenylindene (20.0 g, 76 mmol) in toluene/THF=10/1 solution (230 mL), n-butyllithium solution (2.5 M, hexane solvent, 22 g) was slowly added thereto in drops at 0° C. and the mixture was stirred for a day at room temperature. And then, (6-t-butoxyhexyl)dichloromethylsilane (1.27 g) was slowly added to the mixture solution in drops at −78° C., and the mixture was stirred for 10 mins and further stirred at room temperature for a day. After separating the organic layer therefrom by adding water thereto, (6-t-butoxyhexyl)(methyl)-bis(2-methyl-4-tert-butyl-phenylindenyl)silane was obtained by distilling the solvent under a reduced pressure.

(4) .sup.1H NMR (500 MHz, CDCl.sub.3, 7.26 ppm): −0.20-0.03 (3H, m), 1.26 (9H, s), 0.50-1.20 (4H, m), 1.20-1.31 (11H, m), 1.40-1.62 (20H, m), 2.19-2.23 (6H, m), 3.30-3.34 (2H, m), 3.73-3.83 (2H, m), 6.89-6.91 (2H, m), 7.19-7.61 (14H, m)

Step 2) Preparation of [(6-t-butoxyhexylmethylsilane-diyl)-bis(2-methyl-4-tert-butylphenylindenyl)]zirconium Dichloride

(5) After dissolving (6-t-butoxyhexyl)(methyl)-bis(2-methyl-4-tert-butyl-phenylindenyl)silane prepared in Step 1 in toluene/THF=5/1 solution (95 mL), n-butyllithium solution (2.5 M, hexane solvent, 22 g) was slowly added thereto in drops at −78° C. and the mixture was stirred for a day at room temperature. After dissolving bis(N,N-diphenyl-1,3-propanediamido)dichlorozirconium bis(tetrahydrofuran) [Zr(C.sub.5H.sub.6NCH.sub.2CH.sub.2NC.sub.5H.sub.6)Cl.sub.2(C.sub.4H.sub.8O).sub.2] in toluene (229 mL), it was slowly added to above reacted solution in drops at −78° C. and the mixture was stirred for a day at room temperature. After cooling the reacted solution to −78° C., HCl ether solution (1 M, 183 mL) was slowly added thereto in drops and the mixture was stirred for 1 hr at 0° C. The solution was filtered and vacuum dried, and then the crystal was precipitated by adding hexane thereto and stirring the same. [(6-t-butoxyhexylmethylsilane-diyl)-bis(2-methyl-4-tert-butylphenylindenyl)]zirconium dichloride (20.5 g, total 61%) was obtained by filtering the precipitated crystal and drying the same under a reduced pressure.

(6) .sup.1H NMR (500 MHz, CDCl.sub.3, 7.26 ppm): 1.20 (9H, s), 1.27 (3H, s), 1.34 (18H, s), 1.20-1.90 (10H, m), 2.25 (3H, s), 2.26 (3H, s), 3.38 (2H, t), 7.00 (2H, s), 7.09-7.13 (2H, m), 7.38 (2H, d), 7.45 (4H, d), 7.58 (4H, d), 7.59 (2H, d), 7.65 (2H, d)

Step 3) Preparation of a Supported Catalyst

(7) After weighing 3 g of silica in a schlenk flask, 52 mmol of methylaluminoxane (MAO) was added thereto and the mixture was reacted at 90° C. for 24 hrs. After precipitation, the upper part was eliminated and the rest was washed twice with toluene. After dissolving 180 μmol of [(6-t-butoxyhexylmethylsilane-diyl)-bis(2-methyl-4-tert-butylphenylindenyl)]zirconium dichloride, the ansa-metallocene compound synthesized in above step, in toluene, the mixture was reacted at 70° C. for 5 hrs. When the precipitation was finished after the reaction, the solution of upper part was eliminated and the left reaction product was washed with toluene and washed with hexane again. After vacuum drying the washed product, 5 g of solid type metallocene catalyst supported on silica was obtained.

Comparative Example

(8) ##STR00005##

Step 1) Preparation of (6-t-butoxyhexyl)(methyl)-bis(2-methyl-4-phenylindenyl)silane

(9) After slowly adding 100 mL of t-butoxyhexyl magnesium chloride solution (about 0.14 mol, ether) to 100 mL of trichloromethylsilane solution (about 0.21 mol, hexane) in drops at −100° C. for 3 hrs, the mixture was stirred at room temperature for 3 hrs. After separating the transparent organic layer from the mixture solution, the transparent liquid phase of (6-t-butoxyhexyl)dichloromethylsilane was obtained by vacuum drying the separated transparent organic layer for eliminating an excess quantity of trichloromethylsilane.

(10) 15.4 mL of n-butyllithium solution (2.5 M, hexane solvent) was slowly added to 77 mL of 2-methyl-4-phenylindene toluene/THF=10/1 solution (34.9 mmol) in drops at 0° C., and the mixture solution was stirred at 80° C. for 1 hr and further stirred at room temperature for a day. After then, 5 g of (6-tert-butoxyhexyl)dichloromethylsilane prepared above was slowly added to the mixture solution in drops at −78° C., and the mixture was stirred for about 10 mins and further stirred at 80° C. for 1 hr. After separating the organic layer therefrom by adding water thereto, the sticky yellow oil (racemic:meso=1:1) was obtained with the yield of 78% by refining the product with a silica column and vacuum drying the same.

(11) .sup.1H NMR (500 MHz, CDCl.sub.3, 7.24 ppm): 0.10 (3H, s), 0.98 (2H, t), 1.25 (9H, s), 1.36˜1.50 (8H, m), 1.62 (8H, m), 2.26 (6H, s), 3.34 (2H, t), 3.81 (2H, s), 6.87 (2H, s), 7.25 (2H, t), 7.35 (2H, t), 7.45 (4H, d), 7.53 (4H, t), 7.61 (4H, d)

Step 2) Preparation of [(6-t-butoxyhexylmethylsilane-diyl)-bis(2-methyl-4-phenylindenyl)]zirconium Dichloride

(12) 3.0 mL of n-butyllithium solution (2.5 M in hexane) was slowly added to 50 mL of (6-tert-butoxyhexyl)(methyl)-bis(2-methyl-4-phenyl)indenylsilane ether/hexane=1/1 solution (3.37 mmol) prepared above in drops at −78° C., the mixture was stirred at room temperature for about 2 hrs and vacuum dried. The yellow solid was obtained by washing the salt with hexane and filtering and vacuum drying the same. After weighing the synthesized ligand salt and bis(N,N-diphenyl-1,3-propanediamido)dichlorozirconium bis(tetrahydrofuran) [Zr(C.sub.5H.sub.6NCH.sub.2CH.sub.2CH.sub.2NC.sub.5H.sub.6)Cl.sub.2(C.sub.4H.sub.8O).sub.2] in a glove box, ether was slowly added thereto in drops at −78° C. and the mixture was stirred at room temperature for a day. After then, the red reaction solution was filtered and separated therefrom, and 4 equivalents of HCl ether solution (1 M) was slowly added thereto in drops at −78° C. and the mixture was stirred for 3 hrs. And then, the ansa-metallocene compound of orange solid form (racemic:meso=10:1) was obtained with the yield of 85% by filtering and vacuum drying the same.

(13) .sup.1H NMR (500 MHz, C.sub.6D.sub.6, 7.24 ppm): 1.19 (9H, s), 1.32 (3H, s), 1.48˜1.86 (10H, m), 2.25 (6H, s), 3.37 (2H, t), 6.95 (2H, s), 7.13 (2H, t), 7.36 (2H, d), 7.43 (6H, t), 7.62 (4H, d), 7.67 (2H, d)

Step 3) Preparation of a Supported Catalyst

(14) A metallocene catalyst supported on silica was prepared according to the same method as in Step 3 of Example, except that the metallocene compound ([(6-t-butoxyhexylmethylsilane-diyl)-bis(2-methyl-4-phenylindenyl)]zirconium dichloride) synthesized above was used.

Experimental Example

(15) 1) Homopolymerization of Propylene

(16) After vacuum drying a 2 L stainless reactor at 65° C. and cooling the same, 1.5 mmol of triethylaluminum, 2 bar of hydrogen, and 770 g of propylene were sequentially added therein at room temperature. After stirring the mixture for 10 mins, 0.048 g of each of the metallocene catalysts prepared in Example and Comparative Example was dissolved in 20 mL of TMA-prescribed hexane and the solution was added to the reactor by nitrogen pressure. And then, after slowly elevating the temperature of the reactor to 70° C., the polymerization was carried out for 1 hr. After the reaction was terminated, unreacted propylene was vented out.

(17) 2) Random Polymerization of Propylene

(18) After vacuum drying a 2 L stainless reactor at 65° C. and cooling the same, 1.5 mmol of triethylaluminum and 770 g of propylene were sequentially added therein at room temperature. After stirring the mixture for 10 mins, 0.048 g of each of the metallocene catalysts prepared in Example and Comparative Example was dissolved in 20 mL of TMA-prescribed hexane and the solution was added to the reactor by nitrogen pressure. And then, after slowly elevating the temperature of the reactor to 70° C. with adding 15 g of ethylene therein, the polymerization was carried out for 1 hr. After the reaction was terminated, unreacted propylene and ethylene were vented out.

(19) 3) Measuring Method of the Properties of the Polymer.

(20) (1) Catalytic activity: the ratio of the weight of the produced polymer (kg PP) to the amount of the catalyst used (mmol and g of catalyst) was calculated, based on unit time (h).

(21) (2) Melting point of polymer (Tm): melting point of polymer was measured by using a Differential Scanning calorimeter (DSC, Device Name: DSC 2920, Manufacturer: TA instrument). Specifically, after the polymer was heated to 220° C. and the temperature was maintained for 5 mins, the temperature was decreased to 20° C. again. And then, the temperature was increased again. At this time, the scanning speed of heating and cooling processes was respectively 10° C./min.

(22) (3) Crystallization temperature of polymer (Tc): crystallization temperature was determined from the DSC curve obtained while decreasing the temperature with the same condition as the measurement on melting point by using the DSC.

(23) (4) Stereoregularity of polymer (XS): the polymer was added to boiling o-xylene (ortho-xylene) and the amount of unextracted polymer after 1 hr was converted in a weight ratio (%).

(24) Specifically, after preparing 200 mL of o-xylene in a flask, it was filtered with No. 4 filter paper of 200 mm. After drying an aluminum pan for 30 mins in an oven of 150° C., it was cooled in a desiccator and weighed. Subsequently, 100 mL of filtered o-xylene was collected and transferred to the aluminum pan by using a pipette, and all of o-xylene was evaporated by heating the pan to 145 to 150° C. After then, the aluminum pan was vacuum dried under the temperature of 100±5° C. and the pressure of 13.3 kPa for 1 hr. After cooling the aluminum pan in a desiccator, above processes were repeated twice. The blank test of o-xylene itself was finished within the weight error of 0.0002 g. And then, after drying the polymer obtained by the polymerization process of propylene (70° C., 13.3 kPa, 60 mins, vacuum dry), the polymer sample (2 g±0.0001 g) cooled in a desiccator was added in a 500 mL flask and 200 mL of o-xylene was added therein. The flask was connected to nitrogen and cooling water, and o-xylene was continuously refluxed for 1 hr by heating the flask. After cooling the flask below 100° C. by storing the same in the atmosphere, the insoluble material was precipitated by and shaking the flask and adding the same in a thermostatic bath (25±0.5° C.) for 30 mins. The resulted liquid in which precipitate was formed was repeatedly filtered with No. 4 filter paper of 200 mm until it became clean. 100 mL of the resulted liquid filtered clean was added in an aluminum pan that had been weighed after being dried at 150° C. for 30 mins and cooled in a desiccator, and o-xylene was evaporated by heating the aluminum pan to 145 to 150° C. When the evaporation was completed, the aluminum pan was vacuum dried under the temperature of 70±5° C. and the pressure of 13.3 kPa for 1 hr and cooled in a desiccator. The weight of the pan was measured within the error of 0.0002 g by repeating above processes twice.

(25) After calculating the weight % (Xs) of the polymer dissolved in o-xylene by the following Calculation Equation 1, the weight ratio (=100−Xs) of the polymer that was not dissolved in o-xylene was obtained and it was defined as the stereoregularity (XI).

(26) $\begin{array}{cc}\mathrm{Stereoregularity}\left(\mathrm{XI}\right)=100-\mathrm{Xs}\mathrm{Xs}=\left(\frac{\mathrm{Vbo}}{\mathrm{Vb}1}\times \left(W2-W1\right)-\frac{\mathrm{Vbo}}{\mathrm{Vb}2}\times B\right)\text{/}\mathrm{Wo}\times 100& \left[\mathrm{Calculation}\mathrm{Equation}1\right]\end{array}$

(27) In Calculation Equation 1, variations are as follows:

(28) Xs=portion of the polymer dissolved in o-xylene (weight %)

(29) Vb0=initial volume (mL) of o-xylene

(30) Vb1=obtained volume of polymer solubilized in o-xylene (mL)

(31) Vb2=obtained volume of o-xylene used in blank test (mL)

(32) W2=sum (g) of the weights of the aluminium pan and the polymer left in the aluminum pan after evaporating o-xylene

(33) W1=weight of the aluminum pan (g)

(34) W0=initial weight of the polymer (g)

(35) B=average value (g) of the residue in the aluminium pan in blank test

(36) (5) Polydispersity index (PDI) and weight average molecular weight (Mw): weight average molecular weight (Mw) and number average molecular weight (Mn) of the polymer were measured by using a gel permeation chromatography (GPC, manufactured by Water Co.), and the polydispersity index (PDI) was calculated by dividing the weight average molecular weight by the number average molecular weight. At this time, the analyzing temperature was 160° C., the solvent was trichlorobenzene, and the molecular weight was standardized with polystyrene.

(37) 4) Results of the Properties of the Polymer Measured

(38) The conditions of homo and random polymerization and the properties of polypropylene prepared by using each supported metallocene catalyst of Example and Comparative Example are listed in the following Table 1 (homopolymerization) and Table 2 (random polymerization).

(39) TABLE-US-00001 TABLE 1 Example Comparative Example Liquid propylene (g) 770 770 Amount of supported catalyst (mg) 45 60 Polymerization temperature (° C.) 70 70 Hydrogen (ppm) 337 337 Activity (kg/gCat .Math. hr) 10.1 7.1 Tm(° C.) 149.9 148.7 Tc(° C.) 100.7 99.2 Xs(%) 0.70 0.75 XI(%) 99.30 99.25 MFR 7.0 9.8 Mw 289,000 262,000 MWD 2.7 2.9

(40) TABLE-US-00002 TABLE 2 Example Comparative Example Liquid propylene (g) 770 770 Amount of supported catalyst (mg) 45 45 Polymerization temperature (° C.) 70 70 Ethylene (g) 15 15 Activity (kg/gCat .Math. hr) 12.6 9.6 Tm(° C.) 140.1 139.9 Tc(° C.) 87.3 90.3 Xs(%) 0.75 0.85 XI(%) 99.25 99.15 MFR 11.4 19.6 Mw 261,000 217,000 MWD 2.6 2.7

(41) As shown in above Tables, Example in which the metallocene compound having the indenyl groups and a specific substituent at the bridge group according to the present invention was used in the form of a supported catalyst showed high activity enhancement effect in the preparation of polypropylene. Particularly, Example showed very excellent catalytic activities of 10.1 kg/gCat.Math.hr in the homopolymerization and 12.6 kg/gCat.Math.hr in the random polymerization, and the stereoregularity (XI), the characteristic of single site catalyst, of the prepared polymer was maintained at 99.25%-99.30%. Furthermore, the polypropylene polymer prepared in Example 1 showed very excellent characteristics such as the molecular weight distribution (MWD: Mw/Mn) of 2.7.

(42) Furthermore, when the homopolypropylene is prepared at the same condition, the resin of which the molecular weight is increased by about 10% higher than Comparative Example can be prepared, and, particularly, the molecular weight was not decreased noticeably and the high molecular weight was maintained when the random polypropylene was prepared. Particularly, it is possible to prepare the polypropylene resin of lower molecular weight by increasing the amount of hydrogen provided thereto, and thus the polypropylene of wide molecular weight range can be prepared by the present invention. The metallocene compound prepared in Example can be used to prepare the polypropylene having higher molecular weight when it is polymerized at the same condition, because tert-butyl group of the same acts as an electron donor to the indenyl group and increases the cationic characteristic of zirconium, the center metal, and the activity in increased and the reaction speed is enhanced.