Organic compounds -- part of the class 532-570 series – Organic compounds – Aluminum containing
Reexamination Certificate
2000-06-23
2002-02-12
Nazario-Gonzalez, Porfirio (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Aluminum containing
C556S402000, C556S482000, C502S103000, C502S117000, C526S160000, C526S943000, C568S001000
Reexamination Certificate
active
06346636
ABSTRACT:
TECHNICAL FIELD
This invention relates to polymerization cocatalyst compounds containing weakly coordinating Group 13 element anions and to the preparation of olefin polymers using ionic catalyst systems based on organometallic transition metal cationic compounds stabilized by these anions.
BACKGROUND ART
The term “noncoordinating anion” is now accepted terminology in the field of olefin and vinyl monomer polymerization, both by coordination or insertion polymerization and carbocationic polymerization. See, for example, EP 0 277 003, EP 0 277 004, U.S. Pat. No. 5,198,401, U.S. Pat. No. 5,278,119, and Baird, Michael C., et al, J. Am. Chem. Soc. 1994, 116, 6435-6436. The noncoordinating anions are described to function as electronic stabilizing cocatalysts, or counterions, for essentially cationic metallocene complexes which are active for polymerization. The term noncoordinating anion as used here applies both to truly noncoordinating anions and coordinating anions that are at most weakly coordinated to the cationic complex so as to be labile to replacement by olefinically or acetylenically unsaturated monomers at the insertion site. These noncoordinating anions can be effectively introduced into a polymerization medium, or premixed with an organometallic catalyst compound prior to introduction into the polymerization medium, as Bronsted acid salts containing charge-balancing countercations, ionic cocatalyst compounds. See also, the review articles by S. H. Strauss, “The Search for Larger and More Weakly Coordinating Anions”,
Chem. Rev
., 93, 927-942 (1993).
Olefin solution polymerization processes are generally conducted in aliphatic solvents that serve both to maintain reaction medium temperature profiles and solvate the polymer products prepared. However, aryl-group containing activators, such as those having phenyl derivatives and other fused or pendant aryl-group substituents, are at best sparingly soluble in such solvents and typically are introduced in aryl solvents such as toluene. Solution polymerization processes in aliphatic solvents thus can be contaminated with toluene that must be removed to maintain process efficiencies and to accommodate health-related concerns for both industrial manufacturing processes and polymer products from them. Alternatively, relatively insoluble catalyst components can be introduced via slurry methods, but such methods required specialized handling and pumping procedures that complicate and add significant costs to industrial scale plant design and operation. Low solubility can also become disadvantageous should the process involve low temperature operation at some stage such as in typical adiabatic processes run in areas subject to low ambient temperatures. Additionally, separating or counteracting the build up in the recycle system of aromatic catalyst solvents may become another problem. At the same time means of maintaining high molecular weights in olefin polymers while operating at economically preferable high polymerization reaction temperatures and high polymer production rates is highly desirable. It is therefore desirable to identify olefin polymerization cocatalyst activators which are active for polymerization, particularly at elevated temperatures, which are more soluble in aliphatic solvents.
U.S. Pat. No. 5,502,017 addresses ionic metallocene catalysts for olefin polymerization comprising, as a cocatalyst component, a weakly coordinating anion comprising boron substituted with halogenated aryl substituents preferably containing silylalkyl substitution, such as tert-butyldimethyl-silyl. This substitution is said to increase the solubility and thermal stability of the resulting metallocene salts. Examples 3-5 describes the synthesis and polymerization use of the cocatalyst compound triphenylcarbenium tetrakis (4-dimethyl-t-butylsilyl-2,3,5,6-tetrafluorophenyl)borate.
In view of the above there is a continuing need for activating cocatalyst compounds both to improve the industrial economics of solution polymerization and to provide alternative activating compounds for ionic, olefin polymerization catalyst systems.
BRIEF SUMMARY OF THE INVENTION
The invention provides anion-containing cocatalyst precursor compounds which can be combined with organometallic catalyst precursor compounds to form active catalysts for olefin polymerization by insertion, or coordination, and by carbocationic methods. Olefin polymerization can be conducted by subsequent contacting, or in situ catalyst formation essentially concurrent with said contacting, with polymerizable monomers, those having accessible olefinic, acetylenic unsaturation, or with monomers having olefinic unsaturation capable of cationic polymerization. The catalysts according to the invention are suitable for preparing polymers and copolymers from olefinically and acetylenically unsaturated monomers. The anions [A]
−
of the cocatalyst precursor compounds are those containing a central Group 13 core element to which are bound fluoroaryl ligands, at least one of said fluoroaryl ligands being substituted in the para-position with a siloxy group represented by the symbols—OSiR
3
, representing one or more alkyl or alkylsilyl groups. When the anions are to be used with anilinium or ammonium cations, R groups are secondary, or even tertiary alkyl or alkylsilyl groups when capable of use in view of steric hindrance problems.
Preferred invention cocatalyst activator compounds can be represented by the following formula:
[Ct]
+
[M(ArF)
n
((ArF)OSiR
3
)
4−n
]
−
,
where [Ct]
+
is a cation capable of abstracting an alkyl group, or breaking a carbon-metal bond from organometallic compounds containing such, M is a Group 13 element, preferably boron or aluminum, ArF is a fluorinated aryl group, each R is independently selected from C
1
-C
30
hydrocarbyl or hydrocarbylsilyl substituents, preferably attached to the Si atom through a secondary or tertiary carbon atom, and n is 0-3.
DETAILED DESCRIPTION OF THE INVENTION
Exemplary ArF ligands and substituents of the above invention specifically include fluorinated aryl groups, preferably perfluorinated aryl groups, and include substituted ArF groups having substituents additional to the fluorine substitution, such as fluorinated hydrocarbyl groups. Preferred fluorinated aryl groups include phenyl, biphenyl, napthyl and derivatives thereof. The disclosures of U.S. Pat. Nos. 5,198,401, 5,296,433, 5,278,119, 5,447,895, 5,688,634, 5,895,771, WO 93/02099, WO 97/29845, WO 99/43717, WO 99/42467 and copending U.S. application Ser. No. 09/261,627, filed Mar. 3, 1999, and its equivalent WO 99/45042 are particularly instructive as to suitable ArF chemical groups and are incorporated by reference for purposes of U.S. patent practice. It is preferred that at least one third of hydrogen atoms on carbon atoms of the aromatic ligands be replaced by fluorine atoms, and more preferred that the aryl ligands be perfluorinated ligands. Perfluorinated means that each aryl hydrogen atom, other than those substituted with the siloxy substituents of the invention, should be substituted with fluorine or fluorcarbyl substituents, e.g., trifluoromethyl. The term “perfluorinated” also encompasses those aryl ligands in which all but one hydrogen atom in the para position is replaced with fluorene and the para-position hydrogen is replaced with a siloxy group according to the invention.
Essentially any of the defined R groups will be effective for olefin polymerization such as by solution, bulk, slurry and gas phase polymerization processes. Exemplary R groups include methyl, ethyl, n-propyl, iso-propyl, n-butyl, tert-butyl, cyclohexyl, benzyl, methyltrimethylsilyl, methyltriethylsilyl, etc. The R groups may be the same or different, in other words mixed alkyl groups may be located on the siloxy silicon atom. In one embodiment, each R is a C
1-20
hydrocarbyl or hydrocarbylsilyl substituent, preferably attached to the Si of the —O—Si— group through a secondary or tertiary carbon atom. Tertiary-carbon contain
ExxonMobil Chemical Patents Inc.
Faulkner Kevin M
Nazario-Gonzalez Porfirio
Reid Frank E
Runyan Charles E
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