Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Reexamination Certificate
1997-12-08
2001-06-05
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...
C526S943000, C502S117000
Reexamination Certificate
active
06242545
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to catalysts, catalyst systems and their use in olefin polymerization. The invention more particularly relates to substituted hafnium metallocene-type catalyst compounds, catalyst systems thereof and their use in a polymerizing process.
BACKGROUND OF THE INVENTION
The use of bulky ligand transition metal catalyst compounds in polymerization processes to produce a diverse array of new polymers for use in a wide variety of applications and products is well known in the art. Typical bulky ligand transition metal compounds, known as metallocene-type compounds, are generally described as containing one or more ligands capable of &eegr;-5 bonding to the transition metal atom, usually, cyclopentadienyl derived ligands or moieties, in combination with a transition metal selected from Group 4, 5 or 6 or from the lanthanide and actinide series of the Periodic Table of Elements. Predomiantly in the literature the transition metal is from Group 4, particularly either titanium, zirconium or hafnium, and the cyclopentadienyl derived ligand or moiety is substituted with various radicals, typically alkyl radicals, or two or more cyclopentadienyl ligands are joined by a structural bridge, usually an organic or inorganic group, typically, a carbon or silicon atom containing group.
Other forms of these metallocene-type catalyst compounds contain a cyclopentadienyl derived ligand or moiety and a heteroatom containing group bonded to a transition metal, typically titanium, where the cyclopentadienyl ligand or moiety and the heteroatom containing group are joined by a structural bridge, usually a silicon atom containing group. These and other metallocene-type catalyst compounds in combination with an activator form metallocene-type catalyst systems capable of polymeriig various olefin(s), alone or in combination with other olefin(s). Exemplary of the development of these and other metallocene-type catalyst compounds and catalyst systems are described in U.S. Pat. Nos. 5,017,714, 5,055,438, 5,096,867, 5,198,401, 5,229,478, 5,264,405, 5,278,119, 5,324,800, 5,384,299, 5,408,017, 5,491,207 and 5,621,126 all of which are herein fully incorporated by reference.
It is well known in the art, although not fully understood, that where the transition metal of these metallocene-type catalyst compounds is hafnium, often referred to as a “hafnocene”, hafnocene catalyst systems generally, among other characteristics, perform relatively poorly in comparison to their titanium, especially their zirconium equivalents, often referred to as “zirconocenes”. Although hafnocenes will typically polymerize polymers having higher molecular weights than their zirconocene equivalents under similar polymerization conditions, their overall poor activity make them inferior polymerization catalysts. For example, European patent EP 0 284 707 B1 granted Aug. 30, 1995, which is fully incorporated herein by reference, describes a process for polymerizing olefins using a catalyst system, in liquid form containing a chiral, sterorigid bridged hafnium metallocene catalyst compound and an aluminum compound.
Thus, it would be highly advantageous to have a hafnium metallocene-type catalyst system capable of polymerizing olefin(s) with improved catalyst performance.
SUMMARY OF THE INVENTION
This invention relates to a substituted bulky ligand hafnium transition metal metallocene-type catalyst compound and a catalyst system thereof. The invention also relates to a polymerization process for polymerizing one or more olefin(s) utilizing the substituted bulky ligand hafnium transition metal metallocene-type catalyst compound.
In one embodiment, the invention provides for a catalyst system of a bulky ligand hafnium metallocene-type compound where at least one bulky ligand is substituted with a substituent having at least 3 or more non-hydrogen atoms, and an activator. Preferably, the bulky ligand is substituted with a substituent having at least 3 or more carbon atoms or silicon atoms or combinations thereof In a preferred embodiment, the invention provides for an activated catalyst system of a bully ligand hafnium metallocenetype catalyst complex where the bulky ligand is capable of &eegr;-5 bonding to the hafnium transition metal and is substituted with an alkyl substituent having 3 or more carbon atoms, preferably where the alkyl substituent has 3 to 5 carbon atoms, more preferably the alkyl substituent is a linear alky. In one preferred embodiment, the alkyl substituent is at least one n-butyl group, most preferably at least one n-propyl group, substituted to at least one of the bulky ligands.
In yet another embodiment, the invention is directed to a process for polymerizing, preferably in a continuous process, one or more monomer(s) in the presence of the catalyst system or activated catalyst complex described above.
In one preferred embodiment, the above process of the invention is a continuous slurry or gas phase polymerization process.
In another embodiment, the invention is directed to a polymer product produced using the hafnocene catalyst systems or complexes described above, wherein the polymer product contains less than 2 ppm hafnium, preferably less than 1 ppm hafnium.
DETAILED DESCRIPTION OF THE INVENTION
Introduction
The invention is directed toward a hafnium transition metal metallocene-type catalyst system for polymerizing one or more olefin(s). It has been surprisingly discovered that by properly substituting the cyclopentadienyl derived ligand or moiety of a hafiocene results in an improved catalyst system. Unexpectedly where the substituent on the bulky ligand or moiety is a substituent having 3 or more non-hydrogen atoms, preferably 3 or more carbon atoms, preferably an alkyl substituent, for example n-propyl or n-butyl, the catalyst activity of the hafnocene metallocene-type catalyst system is substantially improved. Along with a sufficiently commercially acceptable activity, the hafnocene catalyst systems of the invention produces polymers having higher molecular weights in comparison to its zirconocene equivalents at the same or similar polymerization conditions. It was surprising that the substituted hafnocene of the invention will tend to produce lower density polymer products than its zirconocene equivalent at substantially the same molecular weight.
Catalyst Components and Catalyst Systems
Preferred metallocene catalysts of the invention, for example, are typically those bulky ligand transition metal complexes described by formula (I):
{[(L
p
)
m
M(A
q
)
n
]
+k
}
h
[B′
−j
]
i
where L is a substituted bulky ligand bonded to M, p is the anionic charge of L and m is the number of L ligands and m is 1, 2 or 3; at least one L is substituted with at least one substituent having 3 or more non-hydrogen atoms, preferably having 3 or more carbon atoms or silicon atoms or combination thereof; A is a ligand bonded to M and capable of inserting an olefin between the M—A bond, q is the anionic charge of A and n is the number of A ligands and n is 1, 2, 3 or 4, M is the transition metal hafnium (Hf), and (p×m)+(q×n)+k corresponds to the formal oxidation state of the metal center, where k is the charge on the cation and k is 1, 2, 3 or 4, and B′ is a chemically stable, non-nucleophillic anionic complex, preferably having a molecular diameter of 4 Å or greater and j is the anionic charge on B′, h is the number of cations of charge k, and i the number of anions of charge j such that h×k=j×i.
Any two L and/or A ligands may be bridged to each other and/or unbridged. The catalyst compound may be fit-sandwich compounds having two or more ligands L, which include cyclopentadienyl derived ligands or substituted cyclopentadienyl derived ligands, or half-sandwich compounds having one ligand L, which is a cyclopentadienyl derived ligand or heteroatom substituted cyclopentadienyl derived ligand or hydrocarbyl substituted cyclopentadienyl derived ligand or moiety such as an indenyl ligand, a benz
Jejelowo Moses Olukayode
Kao Sun-Chueh
Jones Lisa Kimes
Rabago R.
Sher Jaimes
Univation Technologies
Wu David W.
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