Polymerization process

Details Polymerization process Polymerization process

2001-03-07

2003-02-18

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...

C526S154000, C526S161000, C526S172000, C526S348600, C526S352000, C502S155000, C502S162000

Reexamination Certificate

active

06521724

ABSTRACT:

FIELD OF THE INVENTION
Processes for the polymerization of olefins in which late transition metal complexes, such as nickel, iron, cobalt and palladium complexes, are used as a polymerization catalyst have improved polymer productivity when an oxidizing agent is present during at least a portion of the polymerization.
TECHNICAL BACKGROUND
Polyolefins, such as polyethylene and polypropylene, are important items of commerce, and many methods have been developed for their production. Commonly a transition metal compound is used as a polymerization catalyst, and recently there has been great interest on the use of late transition metal complexes (Group 8 to Group 10 metals, IUPAC designation) as such polymerization catalysts. While some of these catalysts display excellent productivity of polymer (amount of polymer produced per unit of catalyst) in various types (homogeneous, slurry and gas phase for instance) of polymerization processes, others display relatively low productivity and/or the lifetime of the active catalyst is shorter than that desired in a typical commercial polymerization process.
The cause of these shortcomings for those polymerization catalysts has not been clear, so it has been difficult to rectify them. Generally speaking, while varying polymerization conditions such as temperature, pressure of monomer (if it is a gas), concentration of polymerization catalyst, variation of cocatalyst (such as alkylaluminum compounds), etc., can result in modest improvements in polymer productivity in some instances, often a desired level of productivity is not reached. Therefore methods of making these types of polymerizations more productive are being sought.
U.S. Pat. Nos. 4,710,552, 5,110,928 and 5,210,160 report the use of various halogenated compounds as additives in the polymerization of olefins using Ziegler early transition metal polymerization catalysts, principally to improve the processability of the polyolefins produced. No mention is made of late transition metal catalysts.
WO00/50470 mentions in Example 148 the use of ethyl phenyldichloroacetate in combination with a certain iron containing catalyst in the polymerization of ethylene. There is no mention of any improvement in polymer productivity because of use of the ester.
SUMMARY OF THE INVENTION
This invention concerns a process for the polymerization of an olefin, comprising the step of contacting, under polymerization conditions, said olefin with an olefin coordination polymerization catalyst comprising a complex of a Group 8 to Group 10 metal, wherein an oxidizing agent is present during at least a portion of said contacting.
This invention also concerns an improved process for the polymerization of an olefin in which said olefin is contacted, under polymerization conditions, with an olefin co-ordination polymerization catalyst comprising a complex of a Group 8 through a Group 10 metal, wherein the improvement comprises that an oxidizing agent is present during at least a portion of the contacting of said polymerization catalyst and said olefin.
This invention also concerns a process for improving the productivity of an olefin coordination polymerization catalyst comprising a complex of a Group 8 to Group 10 metal, in a process for producing a polyolefin by contacting an olefin with said polymerization catalyst under conditions to polymerize said olefin, said process comprising the step having an oxidizing agent present during at least a portion of the contacting of said olefin and said polymerization catalyst.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
In the polymerization processes and catalyst compositions described herein, certain groups may be present.
A “hydrocarbyl group” is a univalent group containing only carbon and hydrogen. As examples of hydrocarbyls may be mentioned unsubstituted alkyls, cycloalkyls and aryls. If not otherwise stated, it is preferred that hydrocarbyl groups herein contain 1 to about 30 carbon atoms.
By “saturated” hydrocarbyl is meant a univalent radical that contains only carbon and hydrogen, and contains no carbon-carbon double bonds, triple bonds or aromatic groups.
By “substituted hydrocarbyl” herein is meant a hydrocarbyl group that contains one or more (types of) substituents that do not substantially interfere with the operation of the polymerization catalyst system. Suitable substituents in some polymerizations may include some or all of halo, ester, keto (oxo), amino, imino, carboxyl, phosphite, phosphonite, phosphine, phosphinite, thioether, amide, nitrile, and ether. Preferred substituents when present are halo, ester, amino, imino, carboxyl, phosphite, phosphonite, phosphine, phosphinite, thioether, and amide. Which substituents are useful in which polymerizations may in some cases be determined by reference to U.S. Pat. No. 5,880,241 (incorporated by reference herein for all purposes as if fully set forth). If not otherwise stated, it is preferred that substituted hydrocarbyl groups herein contain 1 to about 30 carbon atoms. Included in the meaning of “substituted” are chains or rings containing one or more heteroatoms, such as nitrogen, oxygen and/or sulfur, and the free valence of the substituted hydrocarbyl may be to the heteroatom. In a substituted hydrocarbyl, all of the hydrogens may be substituted, as in trifluoromethyl.
By “(substituted) hydrocarbylene” is meant a group analogous to hydrocarbyl, except the radical is divalent.
“Alkyl group” and “substituted alkyl group” have their usual meaning (see above for substituted under substituted hydrocarbyl). Unless otherwise stated, alkyl groups and substituted alkyl groups preferably have 1 to about 30 carbon atoms.
By “aryl” is meant a monovalent aromatic group in which the free valence is to the carbon atom of an aromatic ring. An aryl may have one or more aromatic rings which may be fused, connected by single bonds or other groups.
By “substituted aryl” is meant a monovalent aromatic group substituted as set forth in the above definition of “substituted hydrocarbyl”. Similar to an aryl, a substituted aryl may have one or more aromatic rings which may be fused, connected by single bonds or other groups; however, when the substituted aryl has a heteroaromatic ring, the free valence in the substituted aryl group can be to a heteroatom (such as nitrogen) of the heteroaromatic ring instead of a carbon.
By “phenyl” is meant the C6H5- radical, and a phenyl moiety or substituted phenyl is a radical in which one or more of the hydrogen atoms is replaced by a substituent group (which may include hydrocarbyl). Preferred substituents for substituted aryl include those listed above for substituted hydrocarbyl, plus hydrocarbyl.
By “(inert) functional group” herein is meant a group other than hydrocarbyl or substituted hydrocarbyl that is inert under the process conditions to which the compound containing the group is subjected. The functional groups also do not substantially interfere with any process described herein that the compound in which they are present may take part in. Examples of functional groups include some halo groups (for example fluoro and some unactivated chloro) ether such as —OR
31
wherein R
31
is hydrocarbyl or substituted hydrocarbyl. In cases in which the functional group may be near a metal atom, the functional group should not coordinate to the metal atom more strongly than the groups in those compounds are shown as coordinating to the metal atom, that is they should not displace the desired coordinating group.
By an “active halocarbon” is meant a compound that contains carbon and halogen, and optionally hydrogen, and may contain inert functional groups (other than halogen) and, preferably when present in the polymerization process, increases the productivity of the polymerization catalyst by at least 10 percent, based on a similar polymerization without the active halocarbon present.
By a “neutral bidentate ligand” is meant a bidentate ligand that no charge on the ligand (is not ionic in a formal sense if not coordinated to the transition metal).
By a “neutral tridentate ligand” is

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