“Sweet” MAO

Details “Sweet” MAO “Sweet” MAO

1999-12-22

2002-01-22

Nazario-Gonzalez, Porfirio (Department: 1621)

Organic compounds -- part of the class 532-570 series

Organic compounds

Aluminum containing

C556S187000, C502S111000, C502S151000, C502S152000, C502S159000, C502S109000, C526S160000, C526S943000

Reexamination Certificate

active

06340771

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to activators for polymerization catalysts. More particularly the present invention relates to aluminoxane (or alumoxane or polyaluminum oxide) activators which have been treated with a carbohydrate prior to use as activators for polymerization catalysts such as single site catalysts. The present invention also relates to catalyst systems activated with such treated aluminum compounds and to polymerization processes using such treated aluminum compounds.
BACKGROUND OF THE INVENTION
Aluminoxane compounds are known in the art. Generally such compounds may be characterized by the formula I: R
4
2
AlO(R
4
AlO)
m
AIR
4
2
wherein each R
4
is independently selected from the group consisting of C
1-20
hydrocarbyl radicals and m is from 3 to 50, preferably from 5 to 30. Aluminoxane compounds have found use in the polymerization of olefin monomers with single site catalysts such as the bis Cp-type catalysts taught by Exxon Chemical Patents Inc. in a number of patents including for example those by Welbom, Jr., Turner, Hlatky and Canich. The Dow Chemical Company has a number of patents claiming constrained geometry catalysts having a single Cp ligand bridged, typically by a silyl bridge, to another ligand, typically an amido ligand. NOVA Chemicals has filed patents claiming the use of unbridged phosphinimine complexes and ketimide complexes as polymerization catalysts as disclosed by patents in the names of Stephan, Brown, McMeeking, Gao, Spence and Wang. The University of Alberta also has also a number of patents claiming the use of phosphinimine catalysts for the polymerization of olefins such as those in the name of Cavell.
All of the above catalysts may be activated with aluminoxanes or MAO if R
4
is a methyl radical. In recent years there have been a number of variants of MAO.
U.S. Pat. No. 5,547,675 issued Aug. 20, 1996 to Canich, assigned to Exxon Chemical Patents Inc. teaches a catalyst system comprising a mono Cp single site catalyst, an aluminoxane and a modifier. The modifier is a Lewis base or a compound containing one or more Lewis base functionalities which are capable of reacting with a Lewis acid such as trimethyl aluminum. A number of representative compounds are then disclosed in the disclosure. The disclosure does not suggest that carbohydrates would be suitable compounds to react with aluminoxanes.
Of interest is U.S. Pat. No. 4,431,788 issued Feb. 14, 1984 to Kaminsky, assigned to CPC International Inc. This patent does not disclose MAO per se. However, the patent discloses a process for making a starch/polyolefin composition by polymerizing the olefin monomer(s) with a cyclopentadienyl containing transition metal catalyst and starch which has been contacted with aluminum trialkyl. The patent does not suggest treating MAO with starch.
The present invention seeks to provide a relatively lower cost alternative to improving the reactivity of aluminoxane than that disclosed in the prior art.
SUMMARY OF THE INVENTION
The present invention provides a process comprising treating a complex aluminum compound of the formula R
4
2
AlO(R
4
AlO)
m
AIR
4
2
wherein each R
4
is independently selected from the group consisting of C
1-20
hydrocarbyl radicals and m is from 3 to 50, with one or more carbohydrates in a weight ratio of aluminum complex to carbohydrate from 1:100 to 100:1 at a temperature from 0° C. to 200° C. for a time of at least 5 minutes.
In a further aspect, the present invention provides a catalyst system comprising a transition metal complex in the presence of an activator comprising an aluminum complex of the formula R
4
2
AlO(R
4
AlO)
m
AIR
4
2
wherein each R
4
is independently selected from the group consisting of C
1-20
hydrocarbyl radicals and m is from 3 to 50 which has been treated with one or more carbohydrates in a weight ratio of aluminum complex to carbohydrate from 1:100 to 100:1 at a temperature from 0° C. to 200° C., to provide a molar ratio of treated aluminum to transition metal from 5:1 to 1000:1.
In a further embodiment, the present invention provides a process for the polymerization of one or more olefins at a temperature from 50° C. to 250° C. in the presence of the above catalyst system.
BEST MODE
Aluminoxane compounds of the present invention have the formula I: R
4
2
AlO(R
4
AlO)
m
AIR
4
2
wherein each R
4
is independently selected from the group consisting of C
1-20
hydrocarbyl radicals and m is from 3 to 50, preferably from 5 to 30. Most preferably R
4
is selected from the group consisting of C
1-6
, most preferably C
1-4
straight chained or branched alkyl radicals. Suitable alkyl radicals include a methyl radical, an ethyl radical, an isopropyl radical and an isobutyl radical. In some commercially available aluminoxanes R
4
is a methyl radical.
Carbohydrates comprise a broad class of organic chemicals typically having the empirical formula (CH
2
O)
n
. Carbohydrates may be monosaccharides, disaccharides, oligosaccharides and polysaccharides.
Typically the monosaccharides are polyhydroxy aldehydes or ketones or derivatives thereof. Typical monosaccharides comprise from 3 to 6 carbon atoms (C
3-6
) polyhydroxy aldehydes or ketones (i.e. n is 3 to 6). The higher carbon monosaccharides, having 4 or more carbon atoms, may also form ring structures. The monosaccharides have chiral centers and have D- and L- forms. Some of the common monosaccharides include glyceraldehyde, erythrose, thresoe, arabinose, ribose, lyxose, xylose, glucose, mannose, altrose, allose, talose, galactose, idose and gluose. The five and six membered rings may be referred to as furanose and pyranose based on the parent ring structure of either furan (5-membered cyclic ether) or pyran (6-membered cyclic ether).
As the monosaccharides have multiple hydroxyl groups it is also possible to react monosaccharides together (typically by a linkage between the 1 and 4 carbon atoms in the reacting monosaccharides) to produce poly-, oligo- or disaccharides. The disaccharides may be formed by the reaction between two identical monosaccharides as in maltose or two different monosaccharides as in sucrose and lactose.
The oligosaccharides typically comprise from 2 to 10 monosaccharide units. If the oligosaccharide contains only one type of monosaccharide it is a homopolymer, and if the oligosaccharide contains two or more different monosaccharides it is a heteropolymer. Some oligosaccharides include stachyose (a tetrasaccharide), maltopentose (a 5-membered oligosaccharide) and cyclomaltohexaose (a 6-membered cyclic oligosaccharide).
The polysaccharides contain higher numbers of monosaccharide units. The polysaccharides may be linear or branched. In the backbone of the polysaccharide the linkages between monosaccharide units are typically between the 1-carbon and the 4-carbon of adjacent monosaccharide units. The branches are joined to the backbone through 1-carbon (on first monosaccharide on the branch) to 6-carbon (pendant from the monosaccharide of the backbone). Polysaccharides comprising only one type of monosaccharide unit are homoglycans. Polysaccharides comprising two or more monosaccharides are heteroglycans. Heteroglycans may be characterized by the number of different monosaccharide units in the polymer. Polymers of two different monosaccharides are diheteroglycans. Polymers of three different monosaccharides are triheteroglycans. Common unbranched (linear) polysaccharides include cellulose and amylose. A common branched polysaccharide is amylopectin. Cellulose, amylose and amylopectin are all homoglycans. Starch is a mixture of amylose (linear polysaccharide) and amylopectin (a branched polysaccharide) in a weight ratio of about 25 to 85 weight % of linear polysaccharide and 75 to 15 weight % of branched polysaccharide. Waxy starch consists essentially of branched polysaccharides.
In treating the aluminoxane in accordance with the present invention, the weight ratio of carbohydrate to aluminoxane may be from 1:100 to 100:1, preferably from 1:25 to 25:1. The temperature of the treatment may be from 0° C. to 200

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