Propylene polymerization process

Details Propylene polymerization process Propylene polymerization process

2003-03-05

2004-02-17

Teskin, Fred (Department: 1713)

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

Polymers from only ethylenic monomers or processes of...

C526S126000, C526S127000, C526S129000, C526S134000, C526S161000, C526S170000, C526S348200, C526S348500, C526S351000, C526S943000

Reexamination Certificate

active

06693155

ABSTRACT:

FIELD OF THE INVENTION
This invention relates to a process for polymerizing propylene in the presence of a catalyst system which comprises an activator and a [1,2-b]indenoindolyl Group, 4-6 transition metal complex having open architecture.
BACKGROUND OF THE INVENTION
While Ziegler-Natta catalysts are a mainstay for polyolefin manufacture, single-site (metallocene and non-metallocene) catalysts represent the industry's future. These catalysts are often more reactive than Ziegler-Natta catalysts, and they produce polymers with improved physical properties. The improved properties include narrow molecular weight distribution, reduced low molecular weight extractables, enhanced incorporation of &agr;-olefin comonomers, lower polymer density, controlled content and distribution of long-chain branching, and modified melt rheology and relaxation characteristics.
Single-site olefin polymerization catalysts having “open architecture” are generally known. Examples include the so-called “constrained geometry” catalysts developed by scientists at Dow Chemical Company (see, e.g., U.S. Pat. No. 5,064,802), which have been used to produce a variety of polyolefins. “Open architecture” catalysts differ structurally from ordinary bridged metallocenes, which have a bridged pair of pi-electron donors. In open architecture catalysts, only one group of the bridged ligand donates pi electrons to the metal; the other group is sigma bonded to the metal. An advantage of this type of bridging is thought to be a more open or exposed locus for olefin complexation and chain propagation when the complex becomes catalytically active. Simple examples of complexes with open architecture are tert-butylamido(cyclopentadienyl)dimethylsilyl-zirconium dichloride and methylamido(cyclopentadienyl)-1,2-ethanediyl-titanium dimethyl:
Organometallic complexes that incorporate “indenoindolyl” ligands are known (see U.S. Pat. No. 6,232,260 and PCT Int. Appl. WO 99/24446 (“Nifant'ev”)). The '260 patent demonstrates the use of non-bridged bis(indenoindolyl) complexes for making HDPE in a slurry polymerization. Versatility is an advantage of the complexes; by modifying the starting materials, a wide variety of indenoindolyl complexes can be prepared. “Open architecture” complexes are neither prepared nor specifically discussed. Nifant'ev teaches the use of bridged indenoindolyl complexes as catalysts for making polyolefins, including polypropylene, HDPE and LLDPE. The complexes disclosed by Nifant'ev do not have open architecture.
PCT Int. Appl. WO 01/53360 (Resconi et al.) discloses bridged [2,1-b]indenoindolyl complexes having open architecture and their use to produce substantially amorphous propylene-based polymers. Resconi teaches many open architecture complexes but none of them is a [1,2-b]indenoindolyl complex.
Pending Appl. Ser. No. 10/211,085 filed Aug. 2, 2002, now allowed, discloses a process for copolymerizing ethylene with at least one alpha-olefin selected from the group consisting of 1-butene, 1-hexene, and 1-octene in the presence of a catalyst system which comprises an activator and a silica-supported, indenoindolyl Group 4-6 transition metal complex having open architecture to produce an ethylene copolymer having a density less than about 0.910 g/cm
3
. While both [1,2-b] and [2,1-b]indenoindolyl complexes are disclosed, no comparative results between the two configurations are given nor is there any indication of improved activity. The advantage of using the open architecture complexes is stated to be the ability to incorporate comonomers in ethylene polymerizations to form low density polyethylene. Propylene is not disclosed as a monomer or as a comonomer.
Despite the considerable work done in this area, there is much that is not understood. There is a continued need for improved catalysts for propylene polymerizations. One need is improved activity. Improved activity lowers the cost of catalyst per kg of polymer produced. Also, since the catalyst is not removed from the polymer, improved activity lowers the amount of residual transition metal left in the polymer. High levels of residual transition metal can have deleterious effects such as poor aging properties or poor color retention. There is a continued need for high molecular weight elastomeric polypropylene for a variety of applications that require toughness, flexibility and elastic properties.
SUMMARY OF THE INVENTION
The invention is a process for the polymerization of propylene. The polymerization is done in the presence of a catalyst system which comprises an activator and a [1,2-b]indenoindolyl Group 4-6 transition metal complex having open architecture. Surprisingly, the [1,2-b]indenoindolyl complex is much more active than its counterpart [2,1-b]indenoindolyl complex in propylene polymerizations.
DETAILED DESCRIPTION OF THE INVENTION
Catalyst systems useful for the process comprise an activator and a [1,2-b]indenoindolyl Group 4-6 transition metal complex having open architecture. More preferred complexes include a Group 4 transition metal such as titanium or zirconium.
“Indenoindolyl” ligands are generated by deprotonating an indenoindole compound using a potent base. By “indenoindole compound,” we mean an organic compound that has both indole and indene rings. The five-membered rings from each are fused, i.e., they share two carbon atoms. The rings are fused such that the indole nitrogen and the only sp
3
-hybridized carbon on the indenyl ring are “trans” to each other. Such is the case in an indeno[1,2-b] ring system such as:
The [2,1-b] complexes are excluded. For examples of [2,1-b] complexes, see PCT Int. Appl. WO 01/53360 (Resconi et al.).
The 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 fused rings can be present, as long as an indenoindole moiety is present.
Numbering of indenoindoles follows IUPAC Rule A-22. The molecule is oriented as shown below, and numbering is done clockwise beginning with the ring at the uppermost right of the structure in a manner effective to give the lowest possible number to the heteroatom. Thus, 5,10-dihydro-indeno[1,2-b]indole is numbered as follows:
For correct nomenclature and numbering of these ring systems, see the
Ring Systems Handbook
(1998), a publication of Chemical Abstracts Service, Ring Systems File II: RF 33986-RF 66391 at RF 58952 and 58955. (Other examples of correct numbering appear in PCT Int. Appl. WO 99/24446.)
Methods for making indenoindole compounds are well known. Suitable methods and compounds are disclosed, for example, in U.S. Pat. No. 6,232,260, the teachings of which are incorporated herein by reference, and references cited therein, including the method of Buu-Hoi and Xuong,
J. Chem. Soc
. (1952) 2225. Suitable procedures also appear in PCT Int. Appls. WO 99/24446 and WO 01/53360.
[1,2-b]Indenoindolyl complexes useful for the process of the invention have open architecture. By “open architecture,” we mean a complex having a fixed geometry that enables generation of a highly exposed active site when the catalyst is combined with an activator. The metal of the complex is pi-bonded to the indenyl Cp ring and is also sigma-bonded through two or more atoms to the indenyl methylene carbon. (In contrast, many of the bridged indenoindolyl complexes described in the literature have a transition metal that is pi-bonded to the indenyl Cp ring and pi-bonded to another Cp-like group. See, e.g., U.S. Pat. No. 6,232,260 or WO 99/24446).
Preferably, the metal is sigma-bonded to a heteroatom, i.e., oxygen, nitrogen, phosphorus, or sulfur; most preferably, the metal is sigma-bonded to nitrogen. The heteroatom is linked to the indenoindolyl group through a bridging group, which is preferably dialkylsilyl, diarylsilyl, methylene, ethylene, isopropylidene, diphenylmethyle

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