Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Reexamination Certificate
1999-04-27
2002-01-29
Nazario-Gonzalez, Porfirio (Department: 1621)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Polymers from only ethylenic monomers or processes of...
C556S011000, C556S012000, C556S053000, C502S103000, C502S117000, C526S351000, C526S943000
Reexamination Certificate
active
06342568
ABSTRACT:
BACKGROUND OF THE INVENTION
(1) Field of the Invention
The present invention relates to a novel metallocene compound, and a process for preparing a polyolefin polymerizing an olefin by the use of this metallocene compound. More specifically, it relates to a metallocene compound having a specific structure and a process for preparing a polyolefin comprising the step of polymerizing an olefin by the use of the metallocene compound.
(2) Description of the Prior Art
As homogeneous catalysts for olefin polymerization, catalytic systems containing the so-called metallocene compound are well known.
Processes for polymerizing olefins by the use of a catalytic system containing a conventional metallocene compound have been improved from various angles.
In particular, a method for the stereoregular polymerization of an &agr;-olefin has been variously improved since a report was made by W. Kaminsky et al. [Angew. Chem., Vol. 97, p. 507 (1985)].
As an improved example of such a method, there has been reported a metallocene compound having a C2 symmetrical structure in which some of hydrogen atoms on a cyclopentadienyl group constituting a ligand moiety of the metallocene compound are replaced with alkyl groups, and it has been prevalently attempted to improve the stereoregularity of an isotactic polymer obtained from the above-mentioned metallocene compound [Yamazaki et al., Chemistry Letters, p. 1853 (1989), and Japanese Patent Application Laid-Open No. 268307/1992].
Furthermore, as similar attempts, many researches have been reported in which the stereoregularity of an olefin polymer is to be improved by a catalytic system including a metallocene compound which has an ethylenebisindenyl derivative having the C2 symmetrical structure as a ligand [e.g., Organometallics, Vol. 13, p. 954 (1994), J. Organmet. Chem., Vol. 288, p. 63 (1985) and the like].
On the other hand, J. A. Ewen has found that an &agr;-olefin can be polymerized in a syndiotactic stereoregularity by a catalytic system containing a metallocene compound having a Cs symmetrical structure in which a cyclopentadienyl group and a fluorenyl group are linked with dimethylmethane bridge [J. Am. Chem. Soc., Vol. 110, p. 6255 (1988)]. In order to improve this metallocene compound, it has been attempted to further control the stereoregularity by introducing a 2,7-di-tert-butylfluorenyl group in place of the fluorenyl group (Japanese Patent Application Laid-Open No. 69394/1992).
However, it is difficult to synthesize a syndiotactic &agr;-olefin polymer having a high stereoregularity and a low molecular weight by the use of the metallocene compound having the Cs symmetrical structure under practical conditions of, for example, using a large amount of hydrogen, and accordingly it has been desired to further improve the metallocene compound.
SUMMARY OF THE INVENTION
For the purpose of solving the above-mentioned problems, the present inventors have intensively investigated on a metallocene compound having a novel structure capable of synthesizing an &agr;-olefin polymer and a polymerization process in which this metallocene compound is used, and in consequence, the present invention has been completed.
That is to say, the first aspect of the present invention is directed to a novel metallocene compound represented by the formula [1]
wherein R
1
and R
2
are each selected from the group consisting of an alkyl group, an aryl group and a silicon-containing alkyl group; M is a metal selected from the group IV of the periodic table; Q is carbon or silicon; X is a halogen, an alkyl group or an anionic ligand, and they may be selected so as to be the same or a combination of different ones; i is an integer of 1 to 10; n is an integer of 1 to 4; m is an integer of 0 to 4; and h is an integer of 1 to 3.
The second aspect of the present invention is directed to a process for preparing a polyolefin which comprises the step of polymerizing an olefin by the use of a catalytic system containing a metallocene compound containing represented by the formula [1].
DESCRIPTION OF THE PREFERRED EMBODIMENTS
In the present invention, R
1
and R
2
of the formula [1] are each selected from the group consisting of an alkyl group, an aryl group and a silicon-containing alkyl group.
The above-mentioned alkyl group is preferably an alkyl group having 1 to 20 carbon atoms, and typical examples of the alkyl group include methyl, ethyl, n-propyl, isopropyl, 2-methylpropyl, tert-butyl, cyclohexyl, norbornyl and menthyl.
The above-mentioned aryl group is preferably an aryl group having 6 to 20 carbon atoms, and typical examples of the aryl group include phenyl, tolyl and naphthyl.
The above-mentioned silicon-containing alkyl group is preferably a silicon-containing alkyl group having 1 to 20 carbon atoms, and typical examples of the silicon-containing alkyl group include trimethylsilyl and dimethylethylsilyl.
Furthermore, the substitutional position of each of R
1
and R
2
may be any position of the 1-position to 4-position, or the 5-position to 8-position of fluorene; n is in the range of 1 to 4; and m is in the range of 0 to 4.
In the present invention, Q is carbon or silicon, and a cycloalkyl group is formed in which i is in the range of 1 to 10.
Examples of the cycloalkyl group which can be constituted herein include cyclopropylidene, cyclobutylidene, cyclopentylidene, cyclohexylidene, cycloheptylidene, cyclodimethylenesilylene, cyclotrimethylenesilylene, cyclotetramethylenesilylene, cyclopentamethylenesilylene and cycloheptamethylenesilylene.
In the present invention, M of the formula [1] is a metal selected from the group 4 of the periodic table, and examples of M include titanium, zirconium and hafnium.
X of the formula [1] is a halogen, an alkyl group or an anionic ligand, and they may be selected so as to be the same or a combination of different ones.
Typical examples of the halogen include fluorine, chlorine, bromine and iodine.
The alkyl group is preferably an alkyl group having 1 to 20 carbon atoms, and its typical examples include methyl, ethyl, butyl, isopropyl and tert-butyl.
Typical examples of the anionic ligand include organic phosphorus compounds such as trimethylphosphine, triethylphosphine, triphenylphosphine and diphenylmethylphosphine; alkoxy groups such as methoxy, tert-butoxy and phenoxy; and ethers such as tetrahydrofuran (hereinafter referred to as “THF”), diethyl ether, dioxane and 1,2-dimethoxyethane.
Among them, Xs may be the same or a combination of different ones.
In the present invention, examples of the ligand which is a precursor of the metallocene compound represented by the formula [1] include 1-cyclopentadienyl-1-(2,7-ditert-butylfluorenyl)cyclopropane, 1-cyclopentadienyl-1-(2,7-di-tert-butylfluorenyl)cyclobutane, 1-cyclopentadienyl-1-(2,7-di-tert-butylfluorenyl)cyclopentane, 1-cyclopentadienyl-1-(2,7-di-tert-butylfluorenyl)cyclohexane, 1-cyclopentadienyl-1-(2,7-di-tert-butylfluorenyl)cycloheptane, 1-cyclopentadienyl-1-(3,6-di-tert-butylfluorenyl)cyclopropane, 1-cyclopentadienyl-1-(3,6-di-tert-butylfluorenyl)cyclobutane, 1-cyclopentadienyl-1-(3,6-di-tert-butylfluorenyl)cyclopentane, 1-cyclopentadienyl-1-(3,6-di-tert-butylfluorenyl)-cyclohexane, 1-cyclopentadienyl-1-(3,6-di-tert-butylfluorenyl)cycloheptane, 1-cyclopentadienyl-1-(2,7-di(trimethylsilyl)fluorenyl)cyclopropane, 1-cyclopentadienyl-1-(2,7-di(trimethylsilyl)fluorenyl)cyclobutane, 1-cyclopentadienyl-1-(2,7-di(trimethylsilyl)fluorenyl)cyclopentane, 1-cyclopentadienyl-1-(2,7-di(trimethylsilyl)fluorenyl)cyclohexane, 1-cyclopentadienyl-1-(2,7-di(trimethylsilyl)fluorenyl)cycloheptane, 1-cyclopentadienyl-1-(2,7-diphenylfluorenyl)cyclopropane, 1-cyclopentadienyl-1-(2,7-diphenylfluorenyl)cyclobutane, 1-cyclopentadienyl-1-(2,7-diphenylfluorenyl)cyclopentane, 1-cyclopentadienyl-1-(2,7-diphenylfluorenyl)cyclohexane, 1-cyclopentadienyl-1-(2,7-diphenylfluorenyl)cycloheptane, cyclopentadienyl-(2,7-di-tert-butylfluorenyl)cyclodimethylene silane, cyclopentadienyl-(2,7-di-tert-butylfluoren
Ishii Yukio
Michiue Kenji
Sunaga Tadahiro
Yamashita Masahiro
Burns Doane Swecker & Mathis L.L.P.
Mitsui Chemicals Inc.
Nazario-Gonzalez Porfirio
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