Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Reexamination Certificate
2000-05-10
2004-11-02
Lu, Caixia (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Polymers from only ethylenic monomers or processes of...
C502S120000, C502S124000, C502S128000, C502S155000, C502S158000, C526S129000, C526S133000, C526S160000, C526S161000
Reexamination Certificate
active
06812303
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a novel olefin polymerization catalyst and a method for polymerizing an olefin using the catalyst. More particularly, the present invention is concerned with a novel olefin polymerization catalyst comprising: (A) a transition metal compound comprising a transition metal having &eegr;-bonded thereto a cyclic anionic ligand; (B) a mixture of (B-1) an activator compound and (B-2) a specific organometal compound containing an element selected from elements of Groups 1 to 15 of the Periodic Table, the activator compound (B-1) comprising a cation and a noncoordinating, compatible anion and being capable of reacting with the transition metal compound (A) to form a metal complex having a catalytic activity; (C) a solid component having substantially no hydroxyl group; and optionally (D) an organoaluminum compound, wherein the catalyst is obtained by contacting components (A) to (C) and optionally component (D). The olefin polymerization catalyst of the present invention is advantageous not only in that it has high polymerization activity, but also in that an olefin polymer having excellent powder characteristics can be produced by suspension polymerization (slurry polymerization) or gaseous phase polymerization, while preventing the occurrence of adherence of the polymer to the inner wall, agitation blades and the like of a polymerizer. By virtue of such excellent properties, the catalyst of the present invention enables an olefin polymer having excellent powder characteristics to be efficiently produced by a continuous operation of a commercial scale plant. The olefin polymer produced by using the catalyst of the present invention can be advantageously used for producing various articles, such as films, molded articles (such as blow-molded articles, injection-molded articles and rotomolded articles), fibers, pipes, and coating or jacketing materials for electric transmission cables or wires. The present invention is also concerned with a method for producing an olefin homopolymer or olefin copolymer by using this catalyst.
2. Prior Art
Ziegler-Natta catalysts comprising a titanium compound and an organoaluminum compound have been widely known as a catalyst for producing olefin homopolymers and olefin copolymers.
On the other hand, it has recently been found that when a catalyst system comprising a solvent-soluble transition metal compound containing a halide, such as bis(cyclopentadienyl)zirconium dichloride, and an aluminoxane, which is one type of organoaluminumoxy compound, is used for homopolymerization of ethylene or copolymerization of ethylene with an &agr;-olefin, the catalyst system exhibits high polymerization activity. With respect to the details of this technique, reference can be made to, for example, Examined Japanese Patent Application Publication No. 4-12283 (corresponding to DE 3127133.2).
In Unexamined Japanese Patent Application Laid-Open Specification Nos. 60-35006, 60-35007 and 60-35008 (each corresponding to U.S. Pat. No. 4,937,299), it has been proposed to use, as the transition metal compound component of the above catalyst system comprising a transition metal compound and an aluminoxane, a mixture of at least two metallocenes or a substituted metallocene, so as to control the molecular weight and molecular weight distribution of a final ethylene polymer or to improve the copolymerizability of ethylene with an &agr;-olefin.
The catalyst systems proposed in the above-described prior art documents, each comprising a transition metal compound and an organoaluminumoxy compound, are soluble in a polymerization solvent. Therefore, difficult to securely support such a catalyst system on a carrier by a conventional catalyst-supporting method, for example, a method in which both a solution of the catalyst system and a dispersion obtained by dispersing a carrier in a non-solvent for the catalyst system are provided, and the solution of the catalyst system is added to the dispersion containing the non-solvent for the catalyst system, thereby causing the catalyst system to be precipitated and supported on the carrier. When such a catalyst system supported on a carrier by a conventional carrier-supporting method is used in a suspension polymerization or gaseous phase polymerization, a problem arises in that the catalyst system is caused to separate from the carrier during the polymerization so that, as well-known in the art, the catalyst system which has separated from the carrier disadvantageously produces an indefinite form of polymer, rendering it difficult to handle the polymer. Thus, only a polymer having poor powder characteristics is produced. Further, during the polymerization, such an indefinite-form polymer tends to easily adhere to various inside surfaces associated with the polymerizer, such as the inner wall of the polymerizer, the agitation blades, the outer wall of the thermometer and the like, thus forming polymer scales adhering to such inside surfaces. In addition, a part of the catalyst system which has separated from the carrier adheres to the above-mentioned various inside surfaces associated with the polymerizer during the polymerization, so that a polymerization occurs at such inside surfaces, thus forming polymer scales adhering to such inside surfaces. As well-known in the art, the adhesion of the polymer scales to the inside surfaces associated with the polymerizer poses serious problems in that excess heat cannot be efficiently removed from the polymerizer, that the agitation efficiency of the agitation blades is lowered, and that the reaction temperature cannot be accurately measured with the thermometer. These problems make it impossible to continuously perform the polymerization. Therefore, such catalyst systems (comprising a transition metal compound and an organoaluminumoxy compound) cannot be used for commercial scale production of olefin polymers by suspension polymerization or gaseous phase polymerization. Accordingly, the use of these catalyst systems is inevitably limited to a solution polymerization process. However, a solution polymerization process has a problem in that when it is attempted to produce a polymer having a high molecular weight by solution polymerization, the viscosity of the solution of the polymer is considerably increased, so that the productivity of the process becomes very low. Therefore, these catalyst systems are disadvantageous in that commercial application of them is very difficult.
In order to solve the above-mentioned problems, it has been attempted to polymerize an olefin by suspension polymerization or gaseous phase polymerization, using a catalyst comprising a porous inorganic oxide as a carrier, such as silica, alumina or silica-alumina and, carried thereon, at least one compound selected from the group consisting of a transition metal compound and an organoaluminumoxy compound.
For example, Unexamined Japanese Patent Application Laid-Open Specification Nos. 60-106808 and 60-106809 (both of which correspond to EP 0142143) disclose a method in which a first filler is contacted with a highly active catalyst component comprising a hydrocarbon solvent-soluble titanium compound and/or a hydrocarbon solvent-soluble zirconium compound, thereby obtaining a contact-treatment product, and ethylene is homopolymerized or copolymerized with an &agr;-olefin in the presence of not only the above-mentioned contact-treatment product; but also an organoaluminum compound, and a second filler having an affinity to a polyolefin which affinity is equal to or higher than that of the first filler, to thereby obtain a composition comprising an ethylene polymer and the first and second fillers.
However, in this method, it is impossible to strongly bond the highly active catalyst component to the filler, so that not only is the catalyst activity low, but also the obtained ethylene polymer has poor powder characteristics. In addition, in this method, the obtained polymer is inevitably caused to contain fillers, irrespective of whether or not it
Fujiwara Akio
Matsushita Fumio
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