Catalyst – solid sorbent – or support therefor: product or process – Catalyst or precursor therefor – Plural component system comprising a - group i to iv metal...
Reexamination Certificate
2000-03-17
2001-09-04
Wood, Elizabeth D. (Department: 1621)
Catalyst, solid sorbent, or support therefor: product or process
Catalyst or precursor therefor
Plural component system comprising a - group i to iv metal...
C502S103000, C502S113000, C502S117000, C502S152000, C502S155000
Reexamination Certificate
active
06284698
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to certain Group 3, 4 or Lanthanide metal complexes possessing two metal centers in which both metal centers are activated so as to possess at least partial ligand separation or ion formation. The invention further relates to polymerization catalysts comprising the foregoing metal complexes possessing two metal centers, use thereof in addition polymerizations to prepare olefin polymers, and the resulting olefin polymers, particularly polymers having improved physical properties.
Biscyclopentadienyl Group 4 transition metal complexes in which the metal is in the +4, +3 or +2 formal oxidation state, and olefin polymerization catalysts formed from such by combination with an activating agent, for example, alumoxane or ammonium borate, are well known in the art. Thus, U.S. Pat. No. 3,242,099 describes the formation of olefin polymerization catalysts by the combination of biscyclopentadienyl metal dihalides with alumoxane. U.S. Pat. No. 5,198,401 discloses tetravalent biscyclopentadienyl Group 4 transition metal complexes and olefin polymerization catalysts obtained by converting such complexes into cationic forms in combination with a non-coordinating anion. Particularly preferred catalysts are obtained by the combination of ammonium borate salts with the biscyclopentadienyl titanium, zirconium or hafnium complexes. Among the many suitable complexes disclosed are bis(cyclopentadienyl)zirconium complexes containing a diene ligand attached to the transition metal through &sgr;-bonds where the transition metal is in its highest formal oxidation state. R. Mülhaupt, et al.,
J. Organomet. Chem
., 460, 191 (1993), reported on the use of certain binuclear zirconocene derivatives of dicyclopentadienyl-1,4-benzene as catalysts for propylene polymerization.
Constrained geometry metal complexes, including titanium complexes, and methods for their preparation are disclosed in U.S. application Ser. No. 545,403, filed Jul. 3, 1990 (EP-A-416,815); U.S. Pat. No. 5,064,802, U.S. Pat. No. 5,374,696, U.S. Pat. No. 5,055,438, U.S. Pat. No. 5,057,475, U.S. Pat. No. 5,096,867, and U.S. Pat. No. 5,470,993.
Metal complexes of the constrained geometry type containing two metal centers joined by means of a dianionic ligand separate from and unconnected to the ligand groups in such complexes that contain delocalized 7-electrons, are previously taught, but not exemplified, in U.S. Pat. No. 5,055,438.
SUMMARY OF THE INVENTION
According to the present invention there is provided a composition comprising:
1) one or more bimetallic complexes corresponding to the formula:
wherein:
M and M′ are independently Group 3, 4, 5, 6, or Lanthanide metals;
L is a divalent group (or trivalent group if bound to Q) having up to 50 nonhydrogen atoms and containing an aromatic &pgr;-system through which the group is bound to M, said L also being bound to Z;
L′ is a monovalent group or a divalent group (if bound to L″ or Q), or a trivalent group (if bound to both L″ and Q) having up to 50 nonhydrogen atoms and containing an aromatic &pgr;-system through which the group is bound to M′;
L″ is a monovalent group or a divalent group (if bound to L′ or Q), or a trivalent group (if bound to both L′ and Q) having up to 50 nonhydrogen atoms and containing an aromatic &pgr;-system through which the group is bound to M′, or L″ is a moiety comprising boron or a member of Group 14 of the Periodic Table of the Elements, and optionally also comprising nitrogen, phosphorus, sulfur or oxygen, said L″ having up to 20 non-hydrogen atoms;
Z is a moiety comprising boron or a member of Group 14 of the Periodic Table of the Elements, and optionally also comprising nitrogen, phosphorus, sulfur or oxygen, said Z having up to 20 non-hydrogen atoms;
X and X′ independently each occurrence are anionic ligand groups having up to 40 atoms exclusive of the class of ligands containing an aromatic or conjugated dienyl &pgr;-system through which the group is bound to M or M′, or optionally two X groups or two X′ groups together form a divalent, C
4-40
conjugated or nonconjugated dienyl ligand, optionally substituted with one or more hydrocarbyl, silyl, halocarbyl, or halohydrocarbyl groups, that together with M or M′ form a metallocyclopentene moiety; or further optionally, two X groups or two X′ groups together form a neutral, C
4-40
conjugated or nonconjugated diene ligand, optionally substituted with one or more hydrocarbyl, silyl, halocarbyl, or halohydrocarbyl groups, that is &pgr;-bonded to M or M′ respectively.
X″ independently each occurrence is a neutral ligating compound having up to 20 atoms, exclusive of neutral dienes;
Q is a divalent anionic ligand group bound at one terminus to either Z or L and bound at the remaining terminus to either L′ or L″, said Q having up to 20 nonhydrogen atoms; and
x, x′, and x″ are independently integers from 0 to 3; and
2) one or more activating cocatalysts;
wherein activating cocatalyst component 2) causes both metal centers, e.g., M and M′, of the one or more metal complexes 1) to possess at least partial ligand separation or to form an ion or zwitterion such that the composition is catalytically active for the polymerization of addition polymerizable monomers.
More preferably such poly-activated metal complexes are readily soluble in hydrocarbons thereby resulting in complexes having improved stability and longer catalyst lifetimes. Highly preferably, the metal complexes have at least one metal center that is doubly activated, so that two ligand groups thereof are at least partially separated from the metal or each metal forms a dication or a double zwitterion (doppelzwitterion). Most preferably, the poly-activated, bimetallic complex is formally tetracationic, that is, both metal centers thereof exist in the form of dications or double zwitterions (doppelzwitterions), e.g., the complex may be depicted as a tetracation or bis(doppelzwitterion).
Additionally according to the present invention there are provided polymerization catalysts comprising the foregoing poly-activated metal complexes, specially such complexes wherein one or both metal centers are double activated, the use thereof in addition polymerizations to prepare olefin polymers, and the resulting olefin polymers, particularly polymers having improved physical properties.
The invention allows for increased incidence of long chain branching in a polymer formed from a single monomer, especially ethylene, or a mixture of monomers. It is believed, without wishing to be bound by such belief, this is because a vinyl terminated polymer chain formed at one active metal polymerization site (for example due to &bgr;-hydride elimination in the growing polymer chain) has an increased probability of interaction with the adjoined metal center, thereby becoming incorporated into another polymer chain and resulting in the formation of long chain branched polymers. Thus, linking two catalyst centers effectively increases the probability of long chain branched polymer formation by increasing the number of catalytically active metal centers in the vicinity of the in situ formed vinyl terminated polymer. Alternatively, such catalyst compositions allow the artisan to attain increased long chain branching even under conditions that are not particularly conducive for such polymer formation, such as gas phase polymerization processes or solution polymerization processes operated at increased concentrations of ethylene or higher &agr;-olefin. Accordingly, one beneficial result is the preparation of lower density ethylene/&agr;-olefin copolymers (produced at higher &agr;-olefin concentrations) that contain long chain branching or increased quantities of long chain branching. Examples of such polymers are ethylene/&agr;-olefin copolymers, especially ethylene/1-butene-, ethylene/1-hexene- or ethylene/1-octene-copolymers having densities less than 0.895 g/ml, preferably les
Chen Eugene Y.
Feng Shaoguang S.
Graf David D.
Patton Jasson T.
Wilson David R.
Pasterczyk J.
The Dow Chemical Company
Wood Elizabeth D.
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