Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Reexamination Certificate
2001-08-02
2003-06-24
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...
C526S172000, C526S134000, C526S904000, C526S943000, C526S352000, C526S129000, C502S104000
Reexamination Certificate
active
06583242
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a supported catalyst for polymerizing olefins and its method of production. The catalyst comprises a support treated with an effective amount of an alumoxane, an organometallic complex containing at least one indenoindolyl ligand, and an optional activator. The support has a mean particle size of less than about 30 microns.
BACKGROUND OF THE INVENTION
Many olefin polymerization catalysts are known, including conventional Ziegler-Natta catalysts. While these catalysts are inexpensive, they exhibit low activity, produce polymers having narrow to medium molecular weight distributions (M
w
/M
n
>4), and are generally poor at incorporating &agr;-olefin comonomers. To improve polymer properties, highly active single-site catalysts, in particular metallocenes, are beginning to replace Ziegler-Natta catalysts. Although more expensive, the new catalysts give polymers with narrow molecular weight distributions, and good comonomer incorporation, which allows easier production of low-density polymers. One disadvantage of metallocene catalysts is that they tend to produce lower molecular weight polymers at higher temperatures.
Recent attention has focused on developing improved single-site catalysts in which a cyclopentadienyl ring ligand is replaced by a heteroatomic ring ligand. These catalysts may be referred to generally as “heterometallocenes.” One particular type of heterometallocene of interest contains an indenoindolyl ligand as disclosed in U.S. Pat. No. 6,232,260 and PCT Int. Appl. WO 99/24446.
Single-site catalysts are typically soluble in the polymerization reaction medium and are therefore valuable for solution processes. However, for gas-phase, slurry, and bulk monomer processes, it is useful to immobilize the catalyst on a carrier or support in order to control polymer morphology. Much effort has focussed on supporting metallocene and Ziegler-Natta catalysts. Various supports are taught, particularly inorganic oxides. Support modification techniques, which can improve activity, are also known. For example, supports for Ziegler-Natta catalysts modified with organomagnesiums, organosilanes, and organoboranes are disclosed in U.S. Pat. Nos. 4,508,843, 4,530,913, and 4,565,795. Metallocene catalyst support modification with organosilanes and aluminum, zinc, or silicon compounds is taught in U.S. Pat. Nos. 4,808,561 and 5,801,113. U.S. Pat. No. 6,211,311 teaches support chemical pretreatment for supported single-site catalysts that contain a polymerization-stable heteroatomic ligand.
For catalysts containing indenoindolyl ligands, both U.S. Pat. No. 6,232,260 and PCT Int. Appl. WO 99/24446 disclose that a support such as silica or alumina can be used. However, neither reference contains an example showing supported catalysts and neither patent discloses benefits of specific support particle size.
In sum, new supported indenoindolyl-containing catalysts and methods of making them are needed. Particularly valuable supported catalysts would have improved catalyst activity.
SUMMARY OF THE INVENTION
The invention is a supported catalyst system and a method of making it. The catalyst system comprises an alumoxane treated support, an organometallic complex that contains at least one indenoindolyl ligand, and an activator. The support has a mean particle size of less than about 30 microns.
We surprisingly found that the particle size and alumoxane modification are key to making superior supported indenoindolyl catalysts for olefin polymerization. In particular, catalysts of the invention are more active in olefin polymerization than comparable catalysts having higher particle size support or for which the support is not modified by alumoxane.
DETAILED DESCRIPTION OF THE INVENTION
Supported catalyst systems of the invention include an indenoindolyl-containing complex, an activator, and a support that has been chemically pretreated with an alumoxane.
The supported catalyst systems of the invention contain an organometallic complex comprising a Group 3 to 10 transition or lanthanide metal, M, and at least one indenoindolyl ligand that is &pgr;-bonded to M. The metal, M, may be any Group 3 to 10 transition or lanthanide metal. Preferably, the catalyst contains a Group 4 to 6 transition metal; more preferably, the catalyst contains a Group 4 metal such as titanium or zirconium.
The organometallic complex of the invention also contains at least one indenoindolyl ligand that is &pgr;-bonded to M. Indenoindolyl ligands are well-known in the art and are taught in U.S. Pat. No. 6,232,260, the teachings of which are incorporated herein by reference. The indenoindolyl ligand is an anionic ligand derived from an indenoindole. An indenoindole is an organic compound that has both indole and indene rings. The five-membered rings from each are fused, i.e., they share two or more carbon atoms. Any of the indenoindolyl ring atoms can be unsubstituted or substituted with one or more groups such as alkyl, aryl, aralkyl, halogen, silyl, nitro, dialkylamino, diarylamino, alkoxy, aryloxy, thioether, or the like. Additional rings can be present, as long as an indenoindole moiety is present.
Suitable indenoindole ligand precursors include, for example, 5,10-dihydroindeno[3,2-b]indole, 4,8,10-trimethyl-5H-indeno[3,2-b]indole, 4-tert-butyl-8-methyl-5,10-dihydroindeno[3,2-b]indole, 4,8-dichloro-5,10-dihydroindeno[3,2-b]indole, 10-methylbenzo[f]-5H-indeno[3,2-b]indole, benzo[g]-5,10-dihydroindeno[3,2-b]indole, 5,10-dihydroindeno[3,2-b]benzo[e]indole, benzo[g]-5,10-dihydroindeno[3,2-b]benzo[e]indole, and the like.
The indenoindolyl ligand is generated by deprotonating a ligand precursor with a base to give an anionic ring system with a high degree of aromaticity (highly delocalized). Reaction of the anion with, e.g., a transition metal halide gives the desired organometallic complex. The indenoindolyl ligand is &pgr;-bonded to M in the complex.
The organometallic complex optionally includes one or more additional polymerization-stable, anionic ligands. Examples include substituted and unsubstituted cyclopentadienyl, fluorenyl, and indenyl, or the like, such as those described in U.S. Pat. Nos. 4,791,180 and 4,752,597, the teachings of which are incorporated herein by reference. Suitable ligands also include substituted and unsubstituted boraaryl, pyrrolyl, indolyl, quinolinyl, pyridinyl, and azaborolinyl as described in U.S. Pat. Nos. 5,554,775, 5,539,124, 5,637,660, and 5,902,866, the teachings of which are also incorporated herein by reference. The organometallic complex also usually includes one or more labile ligands such as halides, alkoxys, siloxys, alkyls, alkaryls, aryls, dialkylaminos, or the like. Particularly preferred are halides, alkyls, and alkaryls (e.g., chloride, methyl, benzyl).
The indenoindolyl and/or polymerization-stable ligands can be bridged. Groups that can be used to bridge the ligands include, for example, methylene, ethylene, 1,2-phenylene, dialkylsilyls, and diarylsilyls. Normally, only a single bridge is included, but complexes with two bridging groups can be used. Bridging the ligand changes the geometry around the transition metal and can improve catalyst activity and other properties, such as molecular weight, comonomer incorporation, and thermal stability.
Suitable activators include alumoxanes. Preferred alumoxanes are polymeric aluminum compounds represented by the cyclic formula (R
1
—Al—O)
s
or the linear formula R
1
(R
1
—Al—O)
s
AlR
1
wherein R
1
is a C
1
-C
5
alkyl group and s is an integer from 1 to about 20. Preferably, R
1
is methyl and s is from about 4 to about 10. Exemplary alumoxane activators are (poly)methylalumoxane (MAO), ethylalumoxane, and diisobutylalumoxane. Optionally, the activator is a trialkyl or triaryl aluminum compound, which preferably has the formula AlR
2
3
where R
2
denotes a C
1
-C
20
hydrocarbyl.
Suitable activators also include substituted or unsubstituted trialk
Beran Debra L.
Maraschin Norma J.
Sartain William J.
Wang Shaotian
Carroll Kevin M.
Equistar Chemicals LP
Lee Rip A.
Wu David W.
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