Metallocene compound and method for producing polymer by using it as polymerization catalyst

A novel metallocene compound and a method for producing a polymer by using the metallocene as a polymerization catalyst. The present catalyst includes a neutral metallocene compound, a cationic metallocene compound, and the compound supported catalyst. The present catalyst can be used to produce a polymer having a characteristic structure and physical properties.

FIELD OF THE INVENTION 
The present invention relates to a novel metallocene compound having 
heteroatomic bridge and a method for producing polymer by using it as 
polymerization catalyst. 
BACKGROUND OF THE INVENTION 
Dong-ho Lee, Keun-byoung Yoon and Wan-su Huh, Macromol. Rapid Commun., 15 
841 (1994) describes the use of cyclodextrin as a support of a 
polymerization catalyst. Also S. Ciruelos, T. Cuenca, P. Gomez-sal, A. 
Manazanero and P. Royo, Orgametallics, 14, 177 (1995) describes the 
synthesis method of tetramethyl disiloxanebis (.eta..sup.5 
-cyclopentadienyl)zirconium dichloride, and their structure 
identification. However, the use of the above dichloride as a 
polymerization catalyst is not suggested. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to provide a metallocene compound 
having heteroatomic bridge which can be used as a catalyst for producing a 
polymer. 
It is another object of the present invention to provide a method for 
producing a homopolymer or copolymer which comprises homopolymerizing or 
copolymerizing a vinyl monomer by using a metallocene compound prepared as 
such or a catalyst prepared by supporting the metallocene compound on a 
support or a catalyst bonded to a support. 
DETAILED DESCRIPTION OF THE INVENTION 
The present invention relates to a novel metallocene compound having a 
heteroatomic bridge and a method for producing a polymer by using it as 
polymerization catalyst. 
Generally, there have been found that various kinds of metallocene 
compounds can be used for the production of a polymer. A metallocene 
compound having a heteroatomic bridge according to the present invention, 
when it is used as a polymerization catalyst, can give the polymer a 
specific structure and physical properties since it has a specific 
structure and a polymerization property. 
The present metallocene compound having a heteroatomic bride (hereinafter, 
referred to as HBM compound) is represented by the formula I or II 
##STR1## 
in which M is Group 3-10 metal element of the Periodic Table, transition 
metal element or lanthanide, 
D1 and D2, independently of one another, are unsubstituted or substituted 
cyclopentadienyl or cyclopentadienyl derivatives or similar compounds 
which are capable of .eta..sup.5 bonding with M, for example indenyl and 
fluorenyl, 
A1 and A2, independently of one another, are Group IV B element of the 
Periodic Table, and A1 and D1 or A2 and Y2 may have spacer between them 
where spacer is carbon, oxygen, nitrogen or phosphorus, 
E is heteroatom, preferably nitrogen, oxygen, phosphorus or sulfur, and 
forming a site between D1 and D2 ligand, 
R1 to R4, independently of one another, are a group selected from the group 
consisting of hydrogen, alkyl, aryl, silyl, alkoxy, arlyoxy, siloxy and 
halogen, alone or combination thereof, or -Sp-Sup (wherein Sp is spacer, 
and Sup is support), 
X is a group selected from the group consisting of hydrogen, alkyl, aryl, 
silyl, alkoxy, arlyoxy, siloxy and halogen, alone or combination thereof, 
n is 0 to 4 depending on kinds of metal and valency, and 
m is 1 or 2, and if m is 2, M is bonded to either D1 or D2. 
In the formula II, Z is a non-coordinating anion which is not coordinated 
or very weakly coordinated to a cationic metal portion having D not to 
inhibit a lewis base from reacting with the metal portion having D of 
cation, preferably [BQ1Q2Q3Q4].sup.- wherein B is trivalent Boron; Q1 to 
Q4, independently of one another, are a radical selected from the group 
consisting of hydrogen anion, dialkylamido, alkoxide, aryloxide, hydrogen 
carbyl, substituted hydrogencarbyl and organic metalloid; and one of Q1 to 
Q4 can be halide. 
An HBM compound according to the present invention is prepared in the 
following three steps: 
##STR2## 
in which A1, A2, E, R1 , R2, R3, R4 and Sp are as defined in the formula I 
or II, 
D is D1 or D2, 
H is halogen atom, 
D.sup.- is D1 or D2 anion as defined in formula I or II, 
T.sup.+ is alkali metal cation, 
R is alkyl or alkoxy, and 
T is alkali metal or thallium. 
An HBM compound according to the present invention can be supported on a 
conventional support in order to be used as a polymerization catalyst. For 
example, compounds of the formula I or II are directly supported on a 
dehydrated support. Examples of a support are silica, alumina, magnesium 
chloride, zeolite, aluminum phosphate or zirconia as well as starch and 
cyclodextrin. Supported catalyst is prepared by dipping a dehydrated 
support in the solution of the formula I or II. In addition to the above 
method wherein the compound of the formula II is directly supported on a 
support, cationic HBM (compound of the formula II) supported catalyst can 
be prepared by supporting a neutral HBM compound (compound of the formula 
I) on a support and activating with a boron compound. The boron compound 
cocatalyst is [R5R6R7C].sup.+ [BQ1Q2Q3Q4].sup.- or [HNR8R9R10].sup.+ 
[BQ1Q2Q3Q4].sup.- wherein R5 to R10 are hydrogen, alkyl, aryl, alkoxy, 
silyl or siloxy, and B and Q1 to Q4 are as defined above. 
Another method for producing polymerization catalyst is to modify a support 
and then produce a metallocene compound according to the present invention 
together with a support as shown in the following reaction scheme 
##STR3## 
in which A1, E, M, D1, D2 and (X).sub.n are as defined in the above, and 
D3 and D4 are identical or different from D1 and D2, and Sp is spacer 
linking surface of support with ligand D, and consisting of carbon, 
oxygen, nitrogen or phosphorus. 
In the above scheme, such Sp can be linked one another through a chemical 
bond having carbon, oxygen, nitrogen and phosphorus. 
An HBM compound according to the present invention, or a catalyst wherein 
an HBM compound is supported on a support or a catalyst wherein an HBM 
compound is bonded to a modified surface of a support can be used to 
prepare a homopolymer or copolymer from vinyl monomer by 
homopolymerization or copolymerization. The vinyl monomer is preferably 
.alpha.-olefin, ethylene, cycloolefin, diene or diolefin, most preferably 
ethylene or propylene. 
The amount of polymerization catalyst used is preferably 10.sup.-7 
-10.sup.-4 mole/l, more preferably 10.sup.-6 -10.sup.-5 mole/l, based on 
the amount of monomer reactant used. 
The polymerization temperature is 0-80.degree. C., and preferably 
20-60.degree. C. 
The HBM compound supported catalyst of the present invention can be used 
with an organic metal compound as cocatalyst. The organic metal compound 
is preferably alkylaluminoxane or organic aluminum compound. The 
alkylaluminoxane is preferably methylaluminoxane or modified 
methylaluminoxane. The organic aluminum compound is more preferably 
AlR.sub.n X.sub.3-n wherein R is C.sub.1 -C.sub.10 alkyl or C.sub.1 
-C.sub.10 aryl, X is halogen and n is an integer of 1 to 3. 
Now, the present invention will be described more specifically with 
reference to Examples hereinafter, however it should be noted that the 
present invention is not intended to be restricted within those specific 
Examples. 
In the Examples, the structure and component of the catalyst prepared, and 
the melting point, crystallization temperature, molecular weight and 
structure of the catalyst active polymer were measured by the following 
method. 
(1) Structure and Component of the Catalyst 
The structure of the catalyst was measured by hydrogen and carbon nuclear 
magnetic resonance (H-NMR or C-NMR), and the component of the catalyst was 
analyzed by induction plasma spectrometer. 
(2) Polymerization of Ethylene 
The polymerization of ethylene was carried out in an glass reactor equipped 
with an external temperature regulator, a magnetic stirrer and a valve for 
introducing monomer and nitrogen. The glass reactor was firstly purged 
with nitrogen. To that reactor were added charged purified toluene and 
methylaluminoxane as cocatalyst in a necessary amount, sufficiently 
stirred and saturated with ethylene. Polymerization was initiated by using 
a necessary amount of catalyst. After a given period of time, 
polymerization was completed by adding a small amount of methanol. The 
resulting mixture was poured into a great amount of methanol to which 
hydrochloric acid had been added. The obtained polymer was washed with 
water and methanol and then dried under a vacuum. 
(3) Activity of Catalyst 
The activity of the catalyst was determined by measuring the weight of 
polyethylene obtained from polymerization, and was shown as kg PE/g 
Zr-atm-h. 
(4) Melting Point and Crystallization Temperature of Polymer 
The melting point and crystallization temperature of the polymer were 
measured by differential scanning calorimeter (DSC) in which a sample is 
warmed up to 200.degree. C. by 20.degree. C./minute increase, left for 5 
minutes and then cooled by 20.degree. C./minute. 
(5) Molecular Weight and Structure of Polymer 
The molecular weight of the polymer was measured by gel permeation 
chromatography with elution with benzene trichloride. The structure of the 
polymer was analyzed by carbon nuclear magnetic resonance (C-NMR).

EXAMPLE 1 
Synthesis of Tetramethyl Disiloxanebis (.eta..sup.5 -cyclo 
pentadienyl)zirconium dichloride 
(a) Synthesis of 1,3-Dicyclopentadienyl Tetramethyldisiloxane 
10 mmol of 1,3-dichlorotetramethyl disiloxane was dissolved in 50 ml of 
THF, and 20 mmol of sodium cyclopentadienylide (2.0 M, THF solution) was 
slowly added to the solution at -78.degree. C. The mixed solution was 
reacted at room temperature for about 5 hours. After the completion of the 
reaction, solvent was removed from the mixture. To that mixture hexane was 
added, and LiCl obtained from the reaction was removed by filtration. The 
removal of solvent from filtrated solution gave the title product as 
yellow liquid in a yield of 90%. 
(b) Synthesis of Tetramethyl Disiloxanebis (.eta..sup.5 -cyclopentadienyl) 
Zirconium Dichloride 
(i) Synthesis Route Starting from ZrCl.sub.4 
10 mmol of 1,3-dicyclopentadienyl tetramethyl disiloxane prepared above was 
dissolved in 50 ml of THF, 20 mmol of n-butyl lithium was added at 
-78.degree. C. to the solution, and stirred at room temperature for 3-5 
hours to give solution containing a lithium-containing intermediate. The 
obtained solution was mixed at -78.degree. C. with THF solution in which 
20 mmol of ZrCl.sub.4 had been dissolved, and the mixed solution was 
reacted at room temperature for 10-15 hours and after completion of the 
reaction solvent was removed. To the resulting mixture was added 30 ml of 
CH.sub.2 Cl.sub.2, filtered to remove LiCl and added 50 ml of filtrated 
hexane to recrystallize the product. Recrystallized solid product was 
recrystallized again in CH.sub.2 Cl.sub.2 or toluene solution to give the 
title product in a yield of 50%. 
(ii) Synthesis Route Starting from ZrCl.sub.2 Me.sub.2 
10 mmol 1,3-dicyclopentadienyl tetramethyl disiloxane solution containing 
the above-described lithium-containing intermediate was prepared by the 
same method in (a) of Example 1. To the separate flask 20 mmol of 
ZrCl.sub.4 was added to 50 ml of THF; and 40 mmol of methyl lithium was 
slowly added at -78.degree. C. to give ZrCl.sub.2 Me.sub.2 solution. The 
above separately prepared two solutions were mixed at -78.degree. C., 
stirred for 2-3 hours, reacted at room temperature for 10 hours and then 
passed through HCl. After completion of passing through HCl, solvent was 
removed. The final product was separated after a product-separating step 
and a purifying step. 
EXAMPLE 2 
Synthesis of Tetramethyl Disiloxanebis (.eta..sup.5 -cyclo pentadienyl) 
Zirconium Dimethylate 
(a) Synthesis Route Starting from ZrCl.sub.4 
10 mmol of tetramethyldisiloxane (.eta..sup.5 -cyclopentadienyl) zirconium 
dichloride prepared in (b) of Example 1 was dissolved in 50 ml of THF and 
20 mmol of methyl lithium was slowly added at -78.degree. C. The mixture 
was stirred at room temperature for 2-5 hours and solvent was removed and 
50 ml of ether was added. LiCl was removed and recrystallized at 
-30.degree. C. to give the title product as dark brown in a yield of 50%. 
(b) Synthesis Route Starting from ZrCl.sub.2 Me.sub.2 
In the method of (b)-(ii) of Example 1, solvent was removed from the 
reaction solution taken before the passing through HCl; ether was added 
and filtered to remove LiCl. Filtrated solution was recrystallized at 
-30.degree. C. to give title product in a yield of 50%. 
EXAMPLE 3 
Polymerization of Ethylene and Thermal Properties and Structure of the 
Polyethylene Polymer 
(1) Properties of the Present Catalyst 
In order to examine the properties of the present catalyst (HBM), catalytic 
activity of a few metallocene polymerization catalysts which can be 
generally used in the polymerization of ethylene, and HBM was measured. 
The melting point and crystallization temperature of the polyethylene 
obtained were also measured. The results are summarized in Table 1 and 
compared with those of commercially available polyethylene. 
TABLE 1 
______________________________________ 
Catalytic activity of various catalysts, 
and thermal properties of polyethylene 
Catalyst System 
Catalytic 
Melting Crystallization 
and PE Activity Point (.degree. C.) 
Temperature (.degree. C.) 
______________________________________ 
Cp.sub.2 ZrCl.sub.2 --MAO 
73.0 133 114 
Ind.sub.2 ZrCl.sub.2 --MAO 
49.3 129 110 
Et(Ind).sub.2 ZrCl.sub.2 --MAO 
20.5 130 117 
HBM--MAO 7.2 133 116 
HBM--MAO* 20.1 117 103 
HDPE -- 142 102 
LLDPE -- 122 102 
LDPE -- 108 89 
______________________________________ 
(note) catalytic activity: kg PE/g Zratm-h 
*in the presence of small amount of propylene 
(2) Thermal Properties of Polymer depending on Polymerization Condition 
Ethylene can be polymerized by using an HBM catalyst obtained above and 
methylaluminoxane as cocatalyst in the presence of a small amount of 
propylene. The effect of the amount of methylaluminoxane and catalyst and 
the polymerization temperature on the catalytic activity and thermal 
properties of the polymer was examined; and the results are summarized in 
Table 2. 
TABLE 2 
______________________________________ 
Catalytic activity and thermal properties of polymer 
depending on the amount of catalyst component in HBM and 
the polymerization temperature 
Temperature 
Catalytic 
Melting Crystallization 
[Al]/[Zr] 
(.degree. C.) 
Activity Point (.degree. C.) 
Temperature (.degree. C.) 
______________________________________ 
4000 40 6.7 116 99 
7000 40 14.4 117 102 
10000 40 20.1 117 103 
10000 55 4.1 98 84 
15000 40 16.5 119 105 
______________________________________ 
Catalytic activity: kg PE/g Zratm-h 
When ethylene was polymerized by using an HBM catalyst prepared by the 
present invention, polymerization activity was smaller than that of 
Cp.sub.2 ZrCl.sub.2, but similar to that of Et(Ind).sub.2 ZrCl.sub.2. The 
melting point and crystallization temperature of the polyethylene obtained 
by using HBM were similar to those of polymer or HDPE obtained by using 
another catalyst, while the thermal properties of PE obtained in the 
presence of a small amount of propylene were similar to those of LLDPE and 
LDPE. The molecular weight of PE can be controlled in the range of 
10.sup.3 -10.sup.5, in particular 1,000-500,000 with the change of the 
catalyst component ratio, polymerization temperature and the amount of 
hydrogen added. The molecular weight disperse is in the range of 1.5-3.0. 
When the polymerization of ethylene was carried out by using HBM catalyst 
according to the present invention in the presence of .alpha.-olefin, 
chain branch of .alpha.-olefin can be formed, which can greatly reduce the 
melting point of the polymer prepared; and thus processability and thermal 
adhesiveness are greatly improved. 
When HBM catalyst according to the present invention is used, 
polymerization and copolymerization of ethylene and .alpha.-olefin are 
feasible to be carried out, and therefore a variety of polyolefins can be 
prepared.