Unbridged monocyclopentadienyl metal complex catalyst and a...

Details Unbridged monocyclopentadienyl metal complex catalyst and a... Unbridged monocyclopentadienyl metal complex catalyst and a...

1999-08-17

2001-07-10

Kelly, Cynthia Harris (Department: 1774)

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

Synthetic resins

Polymers from only ethylenic monomers or processes of...

C526S351000, C526S352000

Reexamination Certificate

active

06258904

ABSTRACT:

FIELD OF THE INVENTION
The invention relates to a catalyst composition for olefin polymerization and a process for polymerizing polyolefins, especially copolymers of ethylene-alpha olefins, ethylene-alpha olefin-dienes, and polypropylene using a metallocene catalyst. More particularly, the invention concerns the polymerization of polyolefins having less than 50% crystallinity using a metallocene catalyst containing a transition metal and an aluminoxane.
BACKGROUND OF THE INVENTION
There has been a growing interest in the use of metallocenes for polyolefin production. Many metallocenes for polyolefin production are difficult and time-consuming to prepare, require large amounts of alumoxane, and exhibit poor reactivity toward higher olefins, especially for making ethylene-alpha olefin copolymers and ethylene-alpha olefin-diene terpolymers. Moreover, the ethylene-alpha olefin copolymers and ethylene-alpha olefin-diene terpolymers prepared using these metallocenes often have undesirably low molecular weights (i.e., Mw less that 50,000).
The so-called “constrained geometry” catalysts such as those disclosed in EP 0 420 436 and EP 0 416 815 can provide a high comonomer response and a high molecular weight copolymer, but are difficult to prepare and purify, and, therefore, are expensive. Another drawback of the bridged amido-cyclopentadienyl titanium catalyst system is that in order to form an active oxide-supported catalyst, it is necessary to use fairly high levels of alumoxane (see, e.g., WO96/16092) or to employ mixtures of aluminum alkyl and an activator based on derivatives of tris(pentafluorophenyl)borane (see, e.g., WO95/07942), itself an expensive reagent, thus raising the cost of running the catalyst. In the constrained geometry catalyst art, such as the angle formed by the cyclopentadienyl centroid, transition metal, and amide nitrogen is critical to catalyst performance. Indeed, comparison of the published result using a bridged amido-cyclopentadienyl titanium systems with similar unbridged systems has generally shown the unbridged analogs to be relatively inactive. One such system, described in U.S. Pat. No. 5,625,016 shows very low activity, while having some of the desirable copolymerization behavior.
In contrast to the constrained geometry catalysts, the catalyst of the invention is unconstrained or unbridged and relatively easily and inexpensively prepared using commercially available starting materials. Further, the level of aluminoxane utilized can be lowered. That is, in the present invention, the precursor can be dried onto a support or with a spray drying material with Al:Ti ratios below 100:1 to form highly active catalysts with similar polymerization behavior to their unsupported analogs of the invention and polymerization behavior similar to constrained catalysts.
In Idemitsu Kosan JPO 8/231622, it is reported that the active catalyst may be formed starting from (C
5
Me
5
)Ti(OMe)
3
and that the polymer formed has a relatively wide or broad compositional distribution. The present invention does not utilize this precursor.
Typically, polyolefins such as EPRs and EPDMs are produced commercially using vanadium catalysts. In contrast to polyolefins produced using vanadium catalysts, those produced by the catalysts of the present invention have high molecular weight and narrower composition distribution (i.e., lower crystallinity at an equivalent alpha olefin content.
There is an on-going need to provide a catalyst employing a metallocene which is easy to prepare, does not require large amounts of aluminoxane and which readily copolymerizes to produce ethylene-alpha olefin copolymers, ethylene-alpha olefin-diene terpolymers, and polypropylene, as well as producing polyethylene.
SUMMARY OF THE INVENTION
Accordingly, the present invention provides a catalyst comprising:
(A) a transition metal compound having the formula: (C
5
R
1
5
)MX
3
, wherein each R
1
substituent is independently selected from the group consisting of hydrogen, a C
1
-C
8
alkyl, an aryl, and a heteroatom-substituted aryl or alkyl, with the proviso that no more than three R
1
substituents are hydrogen; and wherein two or more R
1
substituents may be linked together forming a ring; M is a transition metal of Group IVB of the Periodic Table of the Elements; and X is a halide atom (F, Br, Cl, or I);
(B) a compound having the formula: R
2
OH, wherein R
2
is a C
1
-C
8
alkyl;
(C) a bulky phenol compound having the formula: (C
6
R
3
5
)OH, wherein each R
3
group is independently selected from the group consisting of hydrogen, halide, a C
1
-C
8
alkyl, an aryl, a heteroatom substituted alkyl or aryl, wherein two or more R
3
groups may be linked together forming a ring, and in which at least one R
3
is represented by a C
3
-C
12
linear or branched alkyl located at either or both the 2 and 6 position (i.e., the ortho positions relative to the OH group being in position 1) of the bulky phenol compound; and
(D) an aluminoxane.
There is also provided a polymerization process employing the catalyst composition and a polymer produced using the catalyst. A cable composition is also provided.
DETAILED DESCRIPTION OF THE INVENTION
Catalyst
The catalyst contains a transition metal precursor (Component A), an alcohol (Component B), a substituted bulky phenol (Component C), an aluminoxane (Component D). The catalyst of the invention can be unsupported (that is, in liquid form), supported, spray dried, or used as a prepolymer. Support and/or spray drying material is described as optional Component E.
Component A is a transition metal compound having the formula: (C
5
R
1
5
)MX
3
, wherein each R
1
substituent is independently selected from the group consisting of hydrogen, a C
1
-C
8
alkyl, an aryl, and a heteroatom-substituted aryl or alkyl, with the proviso that no more than three R
1
substituents are hydrogen; and wherein two or more R
1
substituents may be linked together forming a ring; M is a transition metal of Group IVB of the Periodic Table of the Elements; and X is a halide atom (F, Br, Cl, or I). Transition metals can include, for example, titanium, zirconium, and hafnium. Preferably, the transition metal, M, is titanium. Illustrative titanium compounds can include: pentamethylcyclopentadienyltitanium trichloride; pentamethylcyclopentadienyltitanium tribromide; pentamethylcyclopentadienyltitanium triiodide; 1,3-bis(trimethylsilyl)cyclopentadienyl-titanium trichloride; tetramethylcyclopentadienyltitanium trichloride; fluorenyltitanium trichloride; 4,5,6,7-tetrahydroindenyltitanium trichloride; 1,2,3,4,5,6,7,8-octahydro-fluorenyltitanium trichloride; 1,2,3,4-tetrahydrofluorenyl-titanium trichloride; 1,2,3-trimethylcyclopentadienyltitanium trichloride; 1,2,4-trimethylcyclopentadienyltitanium trichloride; 1-n-butyl-3-methyl-cyclopentadienyltitanium trichloride; methylindenyltitanium trichloride; 2-methylindenyltitanium trichloride; and 4,5,6,7-tetrahydro-2-methylindenyltitanium trichloride. Illustrative zirconium and hafnium compounds useful in the catalyst precursor of the invention by replacing titanium in the above-enumerated compounds with zirconium and hafnium. In the precursor, a heteroatom is an atom other than carbon (e.g, oxygen, nitrogen, sulfur and so forth) in the ring of the heterocyclic moiety.
Component B is an alcohol having the formula: R
2
OH, wherein R
2
is a C
1
-C
8
alkyl. Illustrative R
2
OH compounds in which R
2
is alkyl can include, for example, methanol, ethanol, propanol, butanol (including n- and t-butanol), pentanol, hexanol, heptanol, octanol. Preferably, R
2
is a methyl group.
Component C is a bulky phenol compound having the formula: (C
6
R
3
5
)OH, wherein each R
3
group is independently selected from the group consisting of hydrogen, halide, a C
1
-C
8
alkyl, an aryl, a heteroatom substituted alkyl or aryl, wherein two or more R
3
groups may be linked together forming a ring, and in which at least one R
3
is represented by a C
3
-C
12
linear or branched alkyl located at either or both the 2 and 6 position (i.e., the ortho positions relative to the OH

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