Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Reexamination Certificate
1999-09-29
2001-10-02
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...
C526S348200, C526S348600, C526S348500, C526S115000
Reexamination Certificate
active
06297338
ABSTRACT:
FIELD OF THE INVENTION
Polymers with varied and useful properties may be produced in processes using at least two polymerization catalysts, at least one of which is a selected iron or cobalt catalyst, for the synthesis of polyolefins. Novel polymers with improved properties are made using a selected ethylene oligomerization catalyst to form &agr;-olefins and a polymerization catalyst capable of copolymerizing ethylene and &agr;-olefins.
TECHNICAL BACKGROUND
Polyolefins are most often prepared by polymerization processes in which a transition metal containing catalyst system is used. Depending on the process conditions used and the catalyst system chosen, polymers, even those made from the same monomer(s) may have varying properties. Some of the properties which may change are molecular weight and molecular weight distribution, crystallinity, melting point, branching, and glass transition temperature. Except for molecular weight and molecular weight distribution, branching can affect all the other properties mentioned.
It is known that certain transition metal containing polymerization catalysts containing iron or cobalt, are especially useful in polymerizing ethylene and propylene, see for instance U.S. patent applications Ser. No. 08/991372, filed Dec. 16, 1997 now U.S. Pat. No. 5,955,555, filed Sep. 21, 1999, and 09/006031, filed Jan. 12, 1998 now U.S. Pat. No. 6,150,482, filed Nov. 21, 2000 (“equivalents” of World Patent Applications 98/27124 and 98/30612). It is also known that blends of distinct polymers, that vary for instance in molecular weight, molecular weight distribution, crystallinity, and/or branching, may have advantageous properties compared to “single” polymers. For instance it is known that polymers with broad or bimodal molecular weight distributions may often be melt processed (be shaped) more easily than narrower molecular weight distribution polymers. Also, thermoplastics such as crystalline polymers may often be toughened by blending with elastomeric polymers.
Therefore, methods of producing polymers which inherently produce polymer blends are useful especially if a later separate (and expensive) polymer mixing step can be avoided. However in such polymerizations one should be aware that two different catalysts may interfere with one another, or interact in such a way as to give a single polymer.
Various reports of “simultaneous” oligomerization and polymerization of ethylene to form (in most cases) branched polyethylenes have appeared in the literature, see for instance World Patent Application 90/15085, U.S. Pat. Nos. 5,753,785, 5,856,610, 5,686,542, 5,137,994, and 5,071,927, C. Denger, et al,. Makromol. Chem. Rapid Commun., vol. 12, p. 697-701 (1991), and E. A. Benham, et al., Polymer Engineering and Science, vol. 28, p. 1469-1472 (1988). None of these references specifically describes any of the processes herein or any of the branched homopolyethylenes claimed herein.
SUMMARY OF THE INVENTION
This invention concerns a polyethylene which has one or both of a structural index, S
T
, of about 1.4 or more, and a processability index, P
R.
of about 40 or more, provided that if S
T
is less than about 1.4, said polymer has fewer than 20 methyl branches per 1000 methylene groups.
This invention also concerns a polyethylene which has at least 2 branches each of ethyl and n-hexyl or longer and at least one n-butyl per 1000 methylene groups, and has fewer than 20 methyl branches per 1000 methylene groups, and obeys the equation
[&eegr;]<0.0007Mw
0.63
wherein [&eegr;] is the intrinsic viscosity of said polyethylene in 1,2,4-trichlorbenzene at 150° C. and Mw is the weight average molecular weight.
REFERENCES:
patent: 5071927 (1991-12-01), Benham et al.
patent: 5137994 (1992-08-01), Goode et al.
patent: 5595705 (1997-01-01), Walton et al.
patent: 5686542 (1997-11-01), Ostoja-Starzewski et al.
patent: 5753785 (1998-05-01), Reddy et al.
patent: 5856610 (1999-01-01), Tamura et al.
patent: 0 361 363 (1990-04-01), None
patent: WO 90/15085 (1990-12-01), None
patent: WO 96/23010 (1996-08-01), None
patent: WO 98/27124 (1997-12-01), None
patent: WO 99/02472 (1998-07-01), None
patent: WO 99/12981 (1998-09-01), None
E. A. Benham, et al., A Process for the Simultaneous Oligomerization and Copolymerization of Ethylene,Polymer Engineering and Science, 28, No. 22, 1469-1472, Nov. 1988.
Richard W. Barnhart, et al., Synthesis of Branched Polyolefins Using a Combination of Homogeneous Metallocene Mimics,J. Am. Chem. Soc., 120, 1082-1083, 1998, and supplemental material for this paper.
Christoph Denger, et al., Simultaneous oligomerization and polymerization of ethylene,Makromol. Chem., Rapid Commun., 12, 697-701, 1991.
PCT/US99/06769 International Search Report dated Aug. 24, 1999.
Citron Joel David
Cotts Patricia Metzger
Tuminello William Howard
Wang Lin
Cheung William K
E. I. Du Pont de Nemours and Company
Wu David W.
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