Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Reexamination Certificate
1999-03-03
2001-07-17
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...
C526S134000, C526S160000, C526S161000, C526S943000, C526S348600, C526S347000, C502S152000, C502S203000
Reexamination Certificate
active
06262202
ABSTRACT:
TECHNICAL FIELD
This invention relates to the use of noncoordinating anions suitable for stabilization of cationic olefin polymerization catalyst compounds.
BACKGROUND OF THE INVENTION
The term “noncoordinating anion” is now accepted terminology in the field of olefin polymerization, both by coordination or insertion polymerization and carbocationic polymerization. See U.S. Pat. Nos. 5,198,401 and 5,278,119 for early work, and Baird, Michael C., et al, &eegr;
5
-C
5
Me
5
TiMe
3
B(C
6
F
5
)
3
: A Carbocationic Olefin Polymerization Initiator Masquerading as a Ziegler-Natta Catalyst,
J. Am. Chem. Soc.
1994, 116, 6435-6436. The noncoordinating anions are described to function as electronic stabilizing cocatalysts, or counterions, for cationic transition metal complexes which are active for olefin polymerization as illustrated in the above references among many others. The terms as used here and in the references applies both to truly noncoordinating anions and weakly coordinating anions that are not so strongly coordinated to the cationic complex so as to be labile to replacement by olefinically or acetylenically unsaturated monomers at the insertion site.
U.S. Pat. No. 5,198,401 describes a preferred noncoordinating anion tetra(pentaflourophenyl) boron, [B(pfp)
4
]
−
or [B(C
6
F
5
)
4
]
−
, wherein the perfluorinated phenyl ligands on the boron makes the counterion labile and stable to potential adverse reactions with the metal cation complexes. Other aryl radicals are said to be suitable in addition to the phenyl radicals, napthyl and anthracenyl are listed. U.S. Pat. No. 5,296,433 teaches the utility of borane complexes comprising tris(pentafluorophenyl)borane and specific complexing compounds. These complexes are said to allow higher molecular weight polymers when used with metallocenes for olefin polymerizaton due to increased solubility of the complexes in monomer or monomer solutions. WO 97/29845 describes the preparation of the organo-Lewis acid perfluorobiphenylborane, and its use to prepare and stabilize active, olefin polymerization catalysts. These cocatalysts are described as being less coordinating than tris(perfluorophenyl)boron, B(C
6
F
5
)
3
, and thus capable of providing higher catalytic activities. Generic description of the suitable cocatalysts according to the application include those of the formula BR′R″ where B is boron with R′ and R″ representing at least one and maybe more fluorinated biphenyls or other polycyclic groups, such as napthyl, anthryl or fluorenyl.
INVENTION DISCLOSURE
Bulky noncoordinating anions that are surprisingly stable under olefin polymerization conditions such that olefin polymers can be prepared with unexpectedly high molecular weights at essentially equal or greater catalyst efficiencies as prior art cocatalysts are disclosed. Thus the invention is directed to an olefin polymerization process comprising contacting under polymerization conditions one or more ethylenically unsaturated monomers with a catalyst composition comprising at least one organometallic transition metal compound activated to a cationic state and a stabilizing, compatible non-coordinating Group 13 anionic complex having halogenated aromatic ligands in an essentially tetrahedral structure wherein the aromatic groups are polycyclic fused or pendant aromatic rings.
BEST MODE AND EXAMPLES OF THE INVENTION
The invention activating cocatalyst, precursor ionic compounds comprise anionic Group 13 element complexes having at least three halogenated, aryl-substituted aromatic ligands. These invention aromatic ligands consist of polycyclic aromatic hydrocarbons and aromatic ring assemblies in which two or more rings (or fused ring systems) are joined directly to one another or together. These ligands, which may be the same or different, are covalently bonded directly to the metal/metalloid center. In a preferred embodiment the aryl groups of said halogenated tetraaryl Group 13 element anionic complex comprise at least one fused polycyclic aromatic hydrocarbon or pendant aromatic ring. Indenyl, napthyl, anthracyl, heptalenyl and biphenyl ligands are exemplary. The number of fused aromatic rings is unimportant so long as the ring junctions and especially the atom chosen as the point of connection to the Group 13 element center permit an essentially tetrahedral structure. Thus, for example, suitable ligands include those illustrated below. See the polycyclic compound examples in the literature for ligand selection, e.g,
Nomenclature of Organic Compounds
, Chs. 4-5 (ACS, 1974).
The choice of ligand connection point is particularly important. Substituents or ring junctions ortho to the ligand connection point present such steric bulk that adoption of an essentially tetrahedral geometry is largely precluded, and typically should be avoided, that is essentially absent except in mixed ligand systems. Examples of undesirable connection points, such as ortho substitutents or fused rings, are depicted below.
Suitable mixed-ligand Group 13 complexes can include fused rings or ring assemblies with ortho-substituents, or ring junctions, so long as those ligands do not exceed two in number. Thus Group 13 anions with one or two hindered fused ring aromatics with three or two unhindered ligands, where hindered aromatics are those having ortho-substituents or ring junctions (illustration II, above) and unhindered are those without (illustration I, above), will typically be suitable. Tris(perfluorophenyl) (perfluoroanthracyl) borate is an illustrative complex. In this complex the anthracyl ligand is a hindered fused ring having ortho-substituents but its use with three unhindered phenyl ligands allows the complex to adopt a tetrahedral structure. Thus, generically speaking, the Group 13 complexes useful in a accordance with the invention will typically conform to the following formula:
[M(A)
4−n
(B)
n
]
+
where, M is a Group 13 element, A is an unhindered ligand as described above, B is a hindered ligand as described above, and n=1,2.
For both fused aromatic rings and aromatic ring assemblies, halogenation is highly preferred so as to allow for increased charge dispersion that contributes along with steric bulk as independent features decreasing the likelihood of ligand abstraction by the strongly Lewis acidic metallocene cation formed in the catalyst activation. Additionally, halogenation inhibits reaction of the transition metal cation with any remaining carbon-hydrogen bonds of the aromatic rings, and perhalogenation precludes such potential undesirable reactions. Thus it is preferred that at least one third of hydrogen atoms on carbon atoms of the aryl-substituted aromatic ligands be replaced by halogen atoms, and more preferred that the aryl ligands be perhalogenated. Fluorine is the most preferred halogen.
The noncoordinating anions of the invention are suitable for use with any of the ionic catalyst systems known in the art or those in development, where such make use of noncoordinating anions. Catalytically suitable transition metal compounds capable of cationization include the Group 3-10 transition metal compounds known to be capable of olefin polymerization when activated to a stable cationic state. Both homogenous and heterogenous processes, the later of which typically use catalysts supported on polymeric or metal oxide particulate supports are suitable. These include gas phase, solution, slurry and bulk polymerization processes for any homopolymers of ethylenically unsaturated monomers, or copolymers of two or more such monomers, selected from the group consisting of ethylene, propylene, C
4
-C
20
&agr;-olefins, C
5
-C
20
strained ring cyclic olefins (e.g., norbornene, alkyl-substituted norbornene), vinyl aromatic monomers (e.g., styrene and alkyl-substituted styrenes), macromers of up to 1000 or more mer units derived from said monomers. Such processes typically operate in a temperature range of −50° C. to 250° C. and at pressure of 0 to 3000 bar.
Examples of transition metal com
Crowther Donna J.
Folie Bernard J.
Walzer, Jr. John F.
Harlan R.
Univation Technologies LLC
Wu David W.
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