Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Reexamination Certificate
1997-10-08
2001-03-27
Wu, David W. (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Polymers from only ethylenic monomers or processes of...
C526S132000, C526S133000, C526S348000, C526S943000
Reexamination Certificate
active
06207774
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a process for producing an ethylene/&agr;-olefin copolymer of a high-molecular weight with an olefin polymerization catalyst constituted of a metallocene compound, an organoaluminum compound, and an ionizable ionic compound.
2. Description of the Related Art
The low-pressure Ziegler process for polymerization of ethylene or an &agr;-olefin is well known in the related technical fields. The catalyst for the process is generally prepared by treating a mixture of an organometallic compound or hydride of a metal of Group 1A to 3A of Periodic Table with a compound of a transition metal (Group 3B to 2B of Periodic Table) in a suspension or a solution, or in the absence of a solvent or a diluent.
In recent years, other special kinds of catalysts are being developed which are active in olefin polymerization. Examples of the catalysts are combination of a cyclopentadienyl derivative of a metal such as titanium, zirconium, and hafnium (Group 4B of Periodic Table) with aluminoxane. (See, for example, J. Boor: “Ziegler-Natta Catalyst and Polymerization”, Academic Press, New York (1979), and H. Sinn and W. Kaminsky: Adv. Organomet. Chem. 1899 (1980).) These catalysts have ability of forming a stereospecific olefin polymer with high catalyst activity. Japanese Patent Application Laid-Open No. 1-503788 describes a high-pressure high-temperature process for producing ethylene/&agr;-olefin copolymer by use of a transition metal compound and an aluminoxane as the catalyst.
Nevertheless, such catalysts have not been used industrially mainly because of the following reasons: the aluminoxane cannot readily be produced in a reproducible form, hindering preparation of the catalyst and the polymer with required reproducibility, and the expensive aluminoxane has to be used in a considerably high ratio to the transition metal compound to achieve sufficient activity.
To offset the above disadvantages, Japanese Patent Laid-Open No. 3-207704 discloses ionic metallocene compound prepared by reacting a metallocene with an ionizing ionic compound. PCT Application No. WO 92-1723 discloses a process of &agr;-olefin polymerization by use of a catalyst system prepared by reacting a halogenated metallocene with an organometallic compound and then bringing the reaction product into contact with an ionizing ionic compound. This catalyst system is advantageous in olefin polymerization. However, when ethylene and &agr;-olefin are copolymerized by use of such a catalyst system at a high temperature, the resulting copolymer has a low molecular weight disadvantageously.
The inventors of the present invention made comprehensive studies to solve the above problems, and found that an ethylene/&agr;-olefin copolymer having a high molecular weight is obtained with a high catalyst activity by copolymerizing ethylene with &agr;-olefin by use of a specific ionic metallocene catalyst at a temperature of not lower than 120° C. The present invention has been accomplished based on the above findings.
SUMMARY OF THE INVENTION
The present invention intends to provide a process for producing an ethylene/&agr;-olefin copolymer of high molecular weight with high efficiency at a high temperature.
The present invention provides a process for producing an ethylene/&agr;-olefin copolymer of a weight-average molecular weight (Mw) of not less than 40000 by copolymerization of ethylene with an &agr;-olefin having three or more carbons by use of an olefin polymerization catalyst at a polymerization temperature of not lower than 120° C.: the olefin polymerization catalyst comprising, as constitutional components, a) a metallocene compound, b) an ionizing ionic compound, and c) an organoaluminum compound:
the metallocene compound (a) being a compound represented by the general formula (1):
wherein Cp
1
and Cp
2
are independently a substituted or unsubstituted cyclopentadienyl, indenyl, or fluorenyl group; R
1
and R
2
are independently a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted aryl group, or a hydrogen atom; M is titanium or zirconium; R
3
and R
4
are independently a hydrogen atom, a halogen atom, a hydrocarbon group of 1 to an alkoxy group, or an aryloxy group, 12 carbons, the ionizing ionic compound (b) being a compound which is capable of changing the metallocene compound (a) into a cationic form and does not further react the cationic form of the metallocene compound, and the organoaluminum compound (c) being represented by the general formula (2):
wherein R
5
, R
5′
, and R
5″
are independently a hydrogen atom, a halogen atom, an amino group, an alkyl group, an alkoxy group, or an aryl group, at least one thereof being an alkyl group.
REFERENCES:
patent: 5408017 (1995-04-01), Turner et al.
patent: 0 426 638 (1991-05-01), None
patent: 0 513 380 (1992-11-01), None
Die Makromolekulare Chemie, Rapid Communications, vol. 14, No. 2, Feb. 1993, James C.W. Chien, “Olefin Copolymerization and Olefin/Diene Terpolymerization with a Zirconocenium Catalyst System”, pp. 109-114.
Hasegawa Saiki
Sone Makoto
Yano Akihiro
Yasuda Hisami
Lu Caixia
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Tosoh Corporation
Wu David W.
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