Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Reexamination Certificate
1998-05-01
2002-07-16
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...
C526S133000, C526S160000, C526S161000, C526S126000, C502S152000
Reexamination Certificate
active
06420507
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a class of Group 4 metal complexes and to olefin polymerization catalysts derived therefrom that are particularly suitable for use in a polymerization process for preparing polymers by polymerization of &agr;-olefins and mixtures of &agr;-olefins, and to the &agr;-olefins and mixtures of &agr;-olefins resulting therefrom.
BACKGROUND OF THE INVENTION
Constrained geometry metal complexes and methods for their preparation are disclosed in EP-A416,815; EP-A-468,651; EP-A-514,828; EP-A-520,732 and WO93/19104, as well as U.S. Pat. No. 5,055,438, U.S. Pat. No. 5,057,475, U.S. Pat. No. 5,096,867, U.S. Pat. No. 5,064,802, U.S. Pat. No. 5,132,380, U.S. Pat. No. 5,470,993, WO95/00526, and US Provisional Application 60-005913. Variously substituted indenyl containing metal complexes have been taught in U.S. Ser. No. 592,756, filed Jan. 26, 1996, as well as WO 95/14024. The teachings of all of the foregoing patents or the corresponding U.S. patent applications are incorporated herein by reference in their entirety.
Constrained geometry catalysts and other single site or metallocene catalysts are useful to prepare homogeneous olefin polymers. The term “homogeneous olefin polymers” refers to homopolymers or interpolymers of one or more &agr;-olefins which are characterized as having a narrow polydispersity, i.e., an M
w
/M
n
of from 1.5 to 3.0, and, in the case of interpolymers, a homogeneous short chain branching distribution, i.e., wherein each molecule has substantially the same number of short chain branches. Homogeneous olefin polymers are advantageous over Ziegler Natta produced polymers, in that they lack a low molecular weight tail fraction, which translates to improved strength and toughness. Homogeneous olefin polymers are further advantageous over Ziegler Natta produced polymers, in that the catalysts useful to prepare such polymers, particularly the constrained geometry catalysts, readily and efficiently incorporate comonomer, which permits the cost-effective production of polymers having a density of less than 0.910 g/cm
3
which accords good elastomeric properties.
Despite their advantageous features, homogeneous polymers are typically more difficult to process than their Ziegler Natta counterparts, in part due to the absence of the low molecular weight fraction and in part due to the narrowness of the melting region.
One preferred class of homogeneous olefin polymers is the class of substantially linear polymers, which are characterized as having a narrow polydispersity, a homogeneous short chain branching distribution, and the presence of sufficient long chain branching to provide improved rheological properties and resistance to melt fracture. Substantially linear polymers are disclosed and claimed in U.S. Pat. Nos. 5,272,236; 5,278,272; 5,380,810; and EP 659,773; EP 676,421; and WO 94/07930.
An alternate approach to utilizing the preferred substantially linear olefin polymers has been to incorporate into homogeneous olefin polymers effective amounts of polymer processing aids prior to fabrication into films or articles. This is disadvantageous, in that it requires an additional processing step and adds cost to the finished product.
While homogeneous olefin-based elastomers, and particularly substantially linear olefin polymers, have found significant commercial utility, the low density of the elastomers, coupled with the absence of a higher crystallinity non-short chain branched fraction renders such polymers relatively poor in terms of upper service temperature and susceptible to deformation under heat, such as in a clothes dryer.
To improve the upper service temperature of homogeneous olefin polymers which are elastomers, one can blend such polymers with higher crystallinity homogeneous or heterogeneous olefin polymers, either via a physical blend or via an in-reactor mixture produced in a dual reactor system, such as is disclosed in U.S. Ser. No. 510,527, filed on Aug. 2, 1995 (WO 94/171112) and U.S. Ser. No. 208,068, filed on Mar. 8,1994 (EP 619827), each of which is incorporated herein by reference in its entirety.
However, industry would find great advantage in a polymer having elastomeric properties which exhibits a resistance to deformation under heat which is greater than that of a physical or in-reactor blend of the same overally density. Industry would find particular advantage in those of such polymers which have an overall polydispersity of from 1.5 to 3.0, but which have excellent processability, as evidenced by resistance to melt fracture and/or an I
10
/I
2
of at least 10. Industry would find especially particular advantage in those of such polymers which may be produced in a single reactor using a highly efficient catalyst which is resistant to degradation at elevated temperature.
It is noted that U.S. Pat. No. 5,621,126 to Exxon Chemical Patents, Inc., discloses the use of mono(cyclopentadienyl) Group IV B metal compounds to produce ethylene/&agr;-olefin copolymers. U.S. Pat. No. 5,621,126 asserts that catalysts containing an amido group having a hydrocarbyl ligand R′ which is aliphatic or alicyclic and which is bonded to the nitrogen atom through a primary or secondary carbon produce copolymers having a greater degree of &agr;-olefin incorporation than catalysts wherein the hydrocarbyl ligand R′ is bonded to the nitrogen atom through a tertiary carbon atom or wherein R′ bears aromatic carbon atoms. U.S. Pat. No. 5,621,126 asserts that when the R′ ligand is bonded to the nitrogen atom through a secondary carbon atom, the activity of the catalyst is greater when R′ is alicyclic than when R′ is bonded to the nitrogen through a primary carbon atom of an aliphatic group of identical carbon number. U.S. Pat. No. 5,621,126 asserts that as the number of carbon atoms of R′ thereof increases, the productivity of the catalyst system and the molecular weight of the ethylene/&agr;-olefin copolymer increase while the amount of &agr;-olefin comonomer incorporated remains about the same or increases. U.S. Pat. No. 5,621,126 asserts that the more preferred R′ ligand is cyclododecyl.
The compositions of U.S. Pat. No. 5,621,126 are disadvantageous, in that they are believed to lack long chain branching, making them susceptible to melt fracture, and thus, less commercially desirable.
Further, while mono(cyclopentadienyl) Group IV B metal compounds may indeed find great commercial advantage in the polymerization of ethylene/&agr;-olefin interpolymers, those in industry are continually seeking improvements and, in particular, would find advantage in catalysts which withstand higher reaction temperatures than are characteristic of bmono(cyclopentadienyl) catalysts. Such higher reaction temperatures would translate to polymers exhibiting a high degree of vinyl unsaturation, making them especially useful as precursors to functionalized polymers, and enhancing long chain branch incorporation when appropriate polymerization conditions are employed.
SUMMARY OF THE INVENTION
According to the present invention there is provided a product produced by a process for preparing polymers of olefin monomers comprising contacting one or more such monomers with a catalyst comprising:
1) a metal complex corresponding to the formula:
wherein:
M is titanium, zirconium or hafnium in the +2, +3 or +4 formal oxidation state;
A′ is a substituted indenyl group substituted in at least the 2 or 3 position with a group selected from hydrocarbyl, fluoro-substituted hydrocarbyl, hydrocarbyloxy-substituted hydrocarbyl, dialkylamino-substituted hydrocarbyl, silyl, germyl and mixtures thereof, said group containing up to 40 nonhydrogen atoms, and said A′ further being covalently bonded to M by means of a divalent Z group;
Z is a divalent moiety bound to both A′ and M via &sgr;-bonds, said Z comprising boron, or a member of Group 14 of the Periodic Table of the Elements, and also comprising nitrogen, phosphorus, sulfur or oxygen, wherein Z preferably has covalently bonded
Kale Lawrence T.
Mangold Debra J.
Nickias Peter N.
Parikh Deepak R.
Patton Jasson T.
Harlan R.
The Dow Chemical Company
Wu David W.
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