Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Reexamination Certificate
2000-10-31
2004-03-16
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...
C526S114000, C526S161000, C526S165000, C526S346000, C526S347000, C526S943000, C502S113000, C502S152000
Reexamination Certificate
active
06706827
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to new metallocene catalysts for use in preparation of olefin or styrene polymers and polymerization methods using the metallocene catalysts. More specifically, the present invention relates to new metallocene catalysts which are capable of preparing olefin or styrene polymers having a high activity, a good stereoregularity, a high melting point, and a good molecular weight distribution in the presence of a small amount of a co-catalyst. The present invention also relates to polymerization method for preparing such olefin or styrene polymers using the metallocene catalysts.
BACKGROUND OF THE INVENTION
Olefin or styrene polymers are generally prepared by radical polymerization, ionic polymerization, or coordination polymerization using a Ziegler-Natta catalyst. Radical or ionic polymerization provides olefin or styrene polymers having mainly an atactic structure. Coordination polymerization using a Ziegler-Natta catalyst provides olefin or styrene polymers having mainly an isotactic structure.
The polymers are structurally divided into three groups such as atactic polymers, isotactic polymers, and syndiotactic polymers, depending on the position of benzene rings as a side chain in relation to a main chain of molecular structure of the polymers. An atactic structure means that configuration of side chains is irregular. An isotactic structure means that side chains are positioned at one side relative to a main chain. A syndiotactic structure means that side chains are alternatively arranged for a main chain.
The polymers having a syndiotactic structure have been only theoretically known, and practically not prepared until a metallocene catalyst was employed to the preparation methods.
Development of the metallocene catalysts was to provide a syndiotactic polystyrene having a stereoregularity or polyolefins having improved physical properties. The conventional metallocene catalysts have a structure which a Group IV transition metal compound of the Periodic Table of Elements is coordinated with ligands composed of one or two cycloalkanedienyl groups or their derivatives. The Group IV transition b metal of the Periodic Table of Elements contain titanium, zirconium, hafnium, etc. The cycloalkanedienyl groups include a cyclopentadienyl group, an indenyl group, a fluorenyl group, etc.
The metallocene catalysts are usually employed with a co-catalyst. The conventionally used Ziegler-Natta catalysts system is composed of a halogenated titanium compound as a main catalyst and alkylaluminium as a co-catalyst. Example of the halogenated titanium compound is titanium tetrachloride. Example of alkylaluminium is trimethylaluminium and triethylaluminium.
While, recently developed metallocene catalyst system is employed with alkylaluminoxane as a co-catalyst, which is capable of preparing polystyrenes having a stereoregularity or polyolefins having improved physical properties. Alkylaluminoxane is produced by reacting alkylaluminium with H
2
O. Especially, syndiotactic polystyrene has a structure which benzene rings as a side chain is alternatively positioned relative to a main chain of the polymer. The syndiotactic polystyrene has an excellent heat-resistance and physical properties since the polymer has about 270° C. of a melting point (T
m
) due to stereoregularity comparing with the conventional amorphous atactic polystyrene, which is of interest.
European Patent Publication No. 210 615 A2 (1987) discloses a syndiotactic polystyrene having a stereoregularity. Also, the patent discloses cyclopentadienyltitanium trichloride and an alkyl-substituted cyclopentadienyltitanium trichloride such as pentamethylcyclopentadienyltitanium trichloride to prepare syndiotactic polystyrenes. It is known that the metallocene catalysts have a good activity, molecular weight distribution, and syndiotactic index.
U.S. Pat. No. 4,544,762 discloses a preparation method of aluminoxane which can be used as a component of catalysts in the preparation of highly active and homogeneous Ziegler-Natta catalysts.
U.S. Pat. No. 5,026,798 discloses a process for polymerizing &agr;-olefins which utilize certain monocyclopentadienyl metal compounds of a Group IVb transition metal of the Periodic Table of Elements in an aluminoxane activated catalyst system to produce crystalline poly-&agr;-olefins.
U.S. Pat. Nos. 08/844,109 and 08/844,110 disclose a new alkyl bridged binuclear metallocene catalyst (ABBM), silyl bridged binuclear metallocene catalyst (SBBM), and alkyl-silyl bridged binuclear metallocene catalyst (A-SBBM) for preparing a syndiotactic polystyrene having a high activity, a good stereoregularity, a high melting point, and a good molecular weight distribution.
Accordingly, the present inventors have developed new metallocene catalysts for use in preparation of olefin or styrene polymers and polymerization methods for effectively preparing such olefin or styrene polymers using the metallocene catalysts.
OBJECTS OF THE INVENTION
An object of the present invention is to provide metallocene catalysts which are capable of preparing olefin or styrene polymers having a high activity, a good stereoregularity, a high melting point, and a good molecular weight distribution.
Another object of the present invention is to provide highly active metallocene catalysts which are capable of preparing a large amount of olefin or styrene polymers in the presence of a small amount of a co-catalyst.
A further object of the present invention is to provide preparation methods of metallocene catalyst and polymerization methods for effectively preparing olefin or styrene polymers using the metallocene catalysts.
Other objects and advantages of this invention will be apparent from the ensuing disclosure and appended claims.
SUMMARY OF THE INVENTION
The new metallocene catalysts according to the present invention are prepared by reacting a metallocene compound with a compound having at least two functional groups. The metallocene compound is a transition metal compound which a transition metal is coordinated with a main ligand such as cycloalkanedienyl group and an ancillary ligand. Functional groups in the compound having at least two functional groups are selected from the group consisting of a hydroxy group, a thiol group, a primary amine group, a secondary amine group, etc.
The metallocene catalysts of the present invention can be prepared by reacting a metallocene compound with a dianion compound produced by reacting an alkali metal compound with a compound having those functional groups.
The metallocene catalysts according to the present invention have a structure which an ancillary ligand of a metallocene compound is bonded to the functional groups of a compound having at least two functional groups. A structure of the metallocene catalysts can be varied according to the type of metallocene compounds, the type of the compound having at least two functional groups, and the molar ratio of each reactant.
The metallocene catalyst is employed with a co-catalyst for styrene or olefin polymerization. The co-catalyst is an organometallic compound or a mixture of non-coordinated Lewis acid and alkylaluminium as it is widely known. The organometallic compound is usually alkylaluminoxane or organoaluminium compound.
The syndiotactic polystyrenes or polyolefins having high physical properties are prepared by using the catalyst system composed of a metallocene catalyst according to the present invention and a co-catalyst. The monomers for polymerization include styrene, styrene derivatives, or a compound having ethylenically unsaturated double bonds. Those compounds are homopolymerized or copolymerized to give polystyrene or polyolefin having a high activity, a good stereoregularity, a high melting point, and a good molecular weight distribution.
DETAILED DESCRIPTION OF THE INVENTION
The metallocene catalyst according to the present invention is prepared by reacting a metallocene compound with a compound having at least two functional groups. The metallocene catalyst has a structure which an anci
Lyu Yi-Yeol
Yim Jin-Heong
Lu Caixia
Samsung Atofina Co. Ltd.
Woodcock & Washburn LLP
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