Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Reexamination Certificate
2003-06-18
2004-09-07
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...
C526S160000, C526S165000, C526S943000, C502S120000, C502S132000, C502S152000, C502S154000
Reexamination Certificate
active
06787616
ABSTRACT:
The present invention relates to a solid catalyst for olefin polymerization and a process for producing an olefinic polymer using such a solid catalyst. More particularly, it relates to a solid catalyst for olefin polymerization that does not require deashing treatment because of having high polymerization activity and that is useful for efficiently producing an olefinic polymer which is excellent in powder properties such as high bulk density, narrow distribution of particle size and low content of large particles and fine powder and which further has a narrow molecular weight distribution, and a process for producing an olefinic polymer, which comprises polymerizing or copolymerizing an olefin using such a solid catalyst.
Many catalysts for olefin (co)polymerization comprising a zirconocene compound containing Group IVB transition metal in the periodic table and an organoaluminum-oxy compound, and processes for producing ethylene (co)polymers using such catalysts, have been proposed, for example, in JP-A-58-19309, JP-A-60-35006, etc. These catalysts are known to have high olefin polymerization activities in a solution polymerization system.
Further, various supported catalysts having at least one component of a metallocene compound and an organoaluminum-oxy compound supported on a porous inorganic oxide carrier such as alumina or silica/alumina, and methods for (co)polymerization of olefins using them, have been proposed. For example, JP-A-61-108610, JP-A-61-296008, etc., disclose a method for polymerizing an olefin in the presence of a catalyst having a metallocene compound and an organoaluminum-oxy compound supported on a carrier such as an inorganic oxide. Further, JP-A-63-280703, etc. disclose a method for preliminarily activating a catalyst by pre-polymerizing an olefin in the presence of a zirconocene compound, an organoaluminum-oxy compound, an organoaluminum compound and a carrier such as silica.
However, if it was attempted to polymerize or copolymerize an olefin in a slurry polymerization system or in a gas phase polymerization system using such a solid catalyst component as disclosed in such publications, the polymerization activities were remarkably low as compared with the above-mentioned solution polymerization system, and the bulk density of the formed polymer was not fully satisfactory.
On the other hand, a method of modifying an organoaluminum-oxy compound has been proposed for the purpose of improving the polymerization activities of the catalyst. For example, JP-A-6-329714 discloses a polymerization method for an olefin using an organoaluminum-oxy compound modified by a compound having an electron attractive group. Further, JP-A-2000-86672 discloses a polymerization method for an olefin using an organoaluminum-oxy compound obtained by contacting it with an adsorbent and then removing the adsorbent. These methods are capable of improving the polymerization activities, but have drawbacks such that an expensive compound is required for the modification, a part of the expensive organoaluminum-oxy compound is lost by the adsorption treatment or modification treatment, and a step for such modification treatment will be required anew, whereby taking industrialization into consideration, a substantial increase in the cost of the catalyst will be unavoidable.
Usually, an organoaluminum-oxy compound is supplied as a solution in a hydrocarbon solvent such as toluene or heptane. In a readily commercially available solution of an organoaluminum-oxy compound such as aluminoxane, an unreacted trialkylaluminum as a raw material (or an unreacted substance of a trialkylaluminum added for modification) is usually contained in an amount of from 14 to 35 mol % as calculated by Al atom, from the viewpoint of the storage stability of the organoaluminum-oxy compound or due to a difficulty in the production method. If such a commercially available organoaluminum-oxy compound is used to prepare a solid catalyst by means of an inorganic oxide carrier such as silica, which is usually widely employed, and if the solid catalyst thus obtained is used for polymerization of an olefin, there will be a problem such that the catalytic activities will substantially decrease, deposition in the reactor is likely, the molecular weight of the formed polymer will decrease, or the particle properties of the polymer will substantially deteriorate.
Accordingly, it has been necessary to remove the free trialkylaluminum in the organoaluminum-oxy compound solution in a step prior to supporting the organoaluminum-oxy compound on a carrier. Specifically, a solution of an organoaluminum-oxy compound in a hydrocarbon, which is commercially available or prepared by reacting a trialkylaluminum with water, is subjected to distillation to evaporate and remove the solvent and the trialkylaluminum under reduced pressure, and then, the obtained solid of the organoaluminum-oxy compound is redissolved in an organic solvent to be used. Such a preliminary step has had problems such as a loss of a part of the expensive organoaluminum-oxy compound due to formation of a gel by heating and so on, and an inconvenience in its practical use due to remarkable deterioration of the stability of organoaluminum-oxy compound from which the trialkylaluminum has been removed. These will lead to remarkably low productivity in the production for the catalyst and to substantially increasing of the cost of producing the catalyst, in the production of the polymer.
It is an object of the present invention to solve the above-mentioned problems of the prior art and to provide a solid catalyst for olefin polymerization which has high polymerization activities and is useful for efficiently producing an olefin polymer which is excellent in powder properties such as high bulk density, narrow distribution of particle size and low content of large particles and fine powder and which further has a narrow molecular weight distribution, even when e.g. a commercially available organoaluminum-oxy compound containing a trialkylaluminum, which is usually readily available, is used as it is.
The present inventors have conducted an extensive study and as a result, have found it possible to accomplish the above object with a solid catalyst for olefin polymerization in which silica (SiO
2
) is used as a carrier material, and a specific carrier is used which has a specific surface area, a pore volume and an average particle size which are considered to be not necessarily desirable for a carrier, and a metallocene compound and an organoaluminum-oxy compound are supported on such a carrier.
Namely, according to the present invention, it is possible to obtain a solid catalyst for polymerization which has high polymerization activities even in slurry polymerization or gas phase polymerization and which not only is able to efficiently produce an olefinic polymer having a high bulk density, a narrow particle size distribution, excellent powder properties and a narrow molecular weight distribution, but also is free from deterioration of the catalytic activities without carrying out any particularly purification or the like even when a commercially available organoaluminum-oxy compound containing a trialkylaluminum compound, is used.
Thus, the present invention provides a solid catalyst for olefin polymerization, which comprises a silica carrier (A) having a specific surface area of from 600 to 850 m
2
/g, a pore volume of from 0.1 to 0.8 ml/g and an average particle size of from 2 to 12 &mgr;m, and an organoaluminum-oxy compound (B) and a Group IVB transition metal compound (C) containing a ligand having a cyclopentadienyl skeleton, supported on the carrier (A).
Further, the present invention provides a method for producing an olefinic polymer, which comprises polymerizing or copolymerizing an olefin in the presence of the above-mentioned solid catalyst for olefin polymerization and an organoaluminum compound.
It is not clearly understood why such excellent effects can be accomplished by the present invention. However, the following points (1) to (4) may be mentio
Hayashida Yoshihisa
Iida Masashi
Iijima Minoru
Kawahara Masao
Takemori Toshifumi
Lu Caixia
Maruzen Petrochemical Co. Ltd.
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
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