Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Reexamination Certificate
1999-10-22
2001-08-14
Mulcahy, Peter D. (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Polymers from only ethylenic monomers or processes of...
C526S160000, C526S172000, C526S348200
Reexamination Certificate
active
06274684
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a catalyst composition comprising at least two metal compounds useful in olefin polymerization processes to produce polyolefins. Preferably, at least one of the metal compounds is a Group 15 containing metal compound. More preferably, the other metal compound is a bulky ligand metallocene-type catalyst. The present invention also relates to a new polyolefin, generally polyethylene, particularly a multimodal polymer and more specifically, a bimodal polymer, and its use in various end-use applications such as film, molding and pipe.
BACKGROUND OF THE INVENTION
Polyethylenes with a higher density and higher molecular weight are valued in film applications requiring high stiffness, good toughness and high throughput. Such resins are also valued in pipe applications requiring stiffness, toughness and long-term durability, and particularly resistance to environmental stress cracking.
Typical metallocene polymerization catalysts (i.e. those containing a transition metal bound, for example, to at least one cyclopentadienyl, indenyl or fluorenyl group) have recently been used to produce resins having desirable product properties. While these resins have excellent toughness properties, particularly dart impact properties, they, like other metallocene catalyzed polyethylenes, can be difficult to process, for example, on older extrusion equipment. One of the means used to improve the processing of such metallocene catalyzed polyethylenes is to blend them with another polyethylene. While the two polymer blend tends to be more processable, it is expensive and adds a cumbersome blending step to the manufacturing/fabrication process.
Higher molecular weight confers desirable mechanical properties and stable bubble formation onto polyethylene polymers. However, it also inhibits extrusion processing by increasing backpressure in extruders, promotes melt fracture defects in the inflating bubble and potentially, promotes too high a degree of orientation in the finished film. To remedy this, one may form a secondary, minor component of lower molecular weight polymer to reduce extruder backpressure and inhibit melt fracture. Several industrial processes operate on this principle using multiple reactor technology to produce a processable bimodal molecular weight distribution (MWD) high density polyethylene (HDPE) product. HIZEX™, a Mitsui Chemicals HDPE product, is considered the worldwide standard. HIZEX™ is produced in two or more reactors and is costly to produce. In a multiple reactor process, each reactor produces a single component of the final product.
Others in the art have tried to produce two polymers together at the same time in the same reactor using two different catalysts. PCT patent application WO 99/03899 discloses using a typical metallocene catalyst and a conventional Ziegler-Natta catalyst in the same reactor to produce a bimodal MWD HDPE. Using two different types of catalysts, however, result in a polymer whose characteristics cannot be predicted from those of the polymers that each catalyst would produce if utilized separately. This unpredictability occurs, for example, from competition or other influence between the catalyst or catalyst systems used. These polymers however still do not have a preferred balance of processability and strength properties. Thus, there is a desire for a combination of catalysts capable of producing processable polyethylene polymers in preferably a single reactor having desirable combinations of processing, mechanical and optical properties.
SUMMARY OF THE INVENTION
The present invention provides a catalyst composition, a polymerization process using the catalyst composition, polymer produced therefrom and products made from the polymer.
In one embodiment, the invention is directed to a catalyst composition including at least two metal compounds, where at least one metal compound is a Group 15 containing metal compound, and where the other metal compound is a bulky ligand metallocene-type compound, a conventional transition metal catalyst, or combinations thereof.
In one embodiment, the invention is directed to a catalyst composition including at least two metal compounds, where at least one metal compound is a Group 15 containing bidentate or tridentate ligated Group 3 to 14 metal compound, preferably a Group 3 to 7, more preferably a Group 4 to 6, and even more preferably a Group 4 metal compound, and where the other metal compound is a bulky ligand metallocene-type compound, a conventional transition metal catalyst, or combinations thereof In this embodiment it is preferred that the other metal compound is a bulky ligand metallocene-type compound.
In another embodiment, the invention is directed to a catalyst composition including at least two metal compounds, where one metal compound is a Group 3 to 14 metal atom bound to at least one leaving group and also bound to at least two Group 15 atoms, at least one of which is also bound to a Group 15 or 16 atom through another group, and where the second metal compound, is different from the first metal compound, and is a bulky ligand metallocene-type catalyst, a conventional-type transition metal catalyst, or combinations thereof.
In an embodiment, the invention is directed to processes for polymerizing olefin(s) utilizing the above catalyst compositions, especially in a single polymerization reactor.
In yet another embodiment, the invention is directed to the polymers prepared utilizing the above catalyst composition, preferably to a new bimodal MWD HDPE.
DETAILED DESCRIPTION OF THE INVENTION
Introduction
The present invention relates to the use of a mixed catalyst composition where one of the catalysts is a Group 15 containing metal compound. Applicants have discovered that using these compounds in combination with another catalyst, preferably a bulky ligand metallocene type compound, produces a new bimodal MWD HDPE product. Surprisingly, the mixed catalyst composition of the present invention may be utilized in a single reactor system.
Group 15 Containing Metal Compound
The mixed catalyst composition of the present invention includes a Group 15 containing metal compound. The Group 15 containing compound generally includes a Group 3 to 14 metal atom, preferably a Group 3 to 7, more preferably a Group 4 to 6, and even more preferably a Group 4 metal atom, bound to at least one leaving group and also bound to at least two Group 15 atoms, at least one of which is also bound to a Group 15 or 16 atom through another group.
In one preferred embodiment, at least one of the Group 15 atoms is also bound to a Group 15 or 16 atom through another group which may be a C
1
to C
20
hydrocarbon group, a heteroatom containing group, silicon, germanium, tin, lead, or phosphorus, wherein the Group 15 or 16 atom may also be bound to nothing or a hydrogen, a Group 14 atom containing group, a halogen, or a heteroatom containing group, and wherein each of the two Group 15 atoms are also bound to a cyclic group and may optionally be bound to hydrogen, a halogen, a heteroatom or a hydrocarbyl group, or a heteroatom containing group.
In a preferred embodiment, the Group 15 containing metal compound of the present invention may be represented by the formulae:
wherein
M is a Group 3 to 12 transition metal or a Group 13 or 14 main group metal, preferably a Group 4, 5, or 6 metal, and more preferably a Group 4 metal, and most preferably zirconium, titanium or hafnium,
each X is independently a leaving group, preferably, an anionic leaving group, and more preferably hydrogen, a hydrocarbyl group, a heteroatom or a halogen, and most preferably an alkyl.
y is 0 or 1 (when y is 0 group L′ is absent),
n is the oxidation state of M, preferably +3, +4, or +5, and m or e preferably +4,
m is the formal charge of the YZL or the YZL′ ligand, preferably 0, −1, −2 or −3, and more preferably −2,
L is a Group 15 or 16 element, preferably nitrogen,
L′ is a Group 15 or 16 element or Group 14 containing group, preferably carbo
Erickson Kersten Anne
Karol Frederick J.
Kwack Tae Hoon
Loveday Donald R.
Mawson Simon
Cheung William
Jones Lisa Kimes
Mulcahy Peter D.
Sher Jaimes
Univation Technologies LLC
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