Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Reexamination Certificate
1999-02-04
2001-08-28
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...
C526S160000, C526S943000, C526S313000, C526S352000, C502S152000, C502S156000
Reexamination Certificate
active
06281320
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to catalyst systems, both supported and unsupported, and to a process using such catalyst systems for the production of high molecular weight polymers, particularly polyolefins.
BACKGROUND OF THE INVENTION
One major drawback of highly active simple zirconocene dihalide systems such as bis(n-butylcyclopentadienyl)zirconium dichloride for ethylene copolymerization has been the premature chain termination through beta-hydride elimination of the inserted alpha-olefin. As a result, high molecular weight ethylene-alpha olefin copolymers can not be produced by this group of catalysts under commercial operation conditions.
A typical solution for this deficiency has been the replacement of simple cyclopentadienyl groups with structurally more elaborate ligands. The synthesis of such ligands are, in general, time-consuming and laborious; and the resulting catalysts are, very often, less active.
U.S. Pat. No. 4,931,517 assigned to Mitsubishi Petrochemical discloses the use of silicon compounds having an Si—O—C bond as a molecular weight regulator for polyethylene produced using by the combination of certain metallocene and an aluminoxane. However, to be effective in boosting the molecular weight, a Si/Zr ratio of 40 or higher was employed. But with these Si/Zr ratios, the metallocene catalysts employed suffered greater than 50% loss in catalyst activity.
WO 93/13140 assigned to Exxon discloses the use of a phenol component of a catalyst system along with a monocyclopentadienyl Group IVB transition metal compound and aluminoxane. However, the ethylene polymers produced by this catalyst system displayed lower molecular weight.
Indemitsu Kosan's Japanese Application No. H7-160441 (Disclosure No. H8-231622) discloses a catalyst containing a monocyclopentadienyl compound, aluminoxane, and a phenolic compound. However, the phenolic compounds employed are not capable of forming chelatable groups on the 2 and 6 positions, since it is known to lead to deactivation or to show no catalytic activity with a monocyclopentadienyl compound. In this catalyst, the 2,6-substituent is an alkyl group.
EP 0 630 910 assigned to Union Carbide discloses a method for reversibly controlling the activity of an olefin polymerization catalyst by the addition of a Lewis base containing an available pair of electrons capable of forming a dative bond to both the metallocene and the aluminoxane. Here Lewis bases are employed for activity reduction and/or to control static.
It would be desirable to develop some simple modifications that would enable a simple zirconocene system to produce ethylene copolymers with high molecular weights and to maintain high catalytic activity.
SUMMARY OF THE INVENTION
The present invention has solved the above-described problem by (1) replacing the halide ligands, e.g., chloride, of zirconocene dihalides with certain chelatable phenols or (2) by using these phenols as external modifiers for the ziroconcene dihalides. The use of chelatable phenolic groups at the 2 and 6 positions of the catalyst component can increase the molecular weight of the final polymer without a change or reduction in catalyst activity. This obviates the requirement for expensive and laborious ligand synthesis.
Accordingly, there is provided a catalyst system comprising:
Component A having the structure (CpRn)R
1
(1−y)(CpRm)MX
2
wherein M is a metal selected from the group consisting of Ti, Zr, and Hf; each (CpRn) and (CpRm) is independently a cyclopentadienyl or substituted cyclopentadienyl group bonded to M; each R is independently selected from the group consisting an alkyl, a cycloalkyl, an alkenyl, a cycloalkenyl, an aryl, an alkylaryl, or an arylalkyl, each member of this group containing from 1 to 20 carbon atoms; and optionally at least two R moieties are joined together to from a ring having 4 to 6 carbon atoms; R
1
is selected from the group consisting of (i) a C
1
-C
4
substituted or unsubstituted alkenyl radical, (ii) a dialkyl or diaryl of germanium or silicon, (iii) an alkyl or aryl phosphine, and (iv) an amino group bridging two (CpRn) and (CpRm) rings; and each X is independently selected from the group consisting of (i) hydrogen, (ii) a C
1
-C
20
alkyl, (iii) a C
1
-C
20
aryl, (iv) a C
1
-C
20
alkenyl, (v) a C
1
-C
20
alkylaryl, (vi) a C
1
-C
20
arylalkyl (vii) a C
1
-C
20
hydrocarboxy, (viii) a C
1
-C
20
aminoalkyl, and (ix) a halogen; n and m are each 0,1, 2, 3, 4, or 5; and y is 0, or 1;
Component B an aluminoxane; and
Component C a phenol having the formula:
wherein A and D are the same or different and are selected from the group consisting of: —OR′, —NR′
2
, —PR′
2
, —CR′
2
OR′, —CR′
2
NR′
2
, —COR′, —CR′NR′, —COOR′, —CONR′
2
, —OCOR′—NR′COR′, and wherein each R′ is the same or different and are independently selected from the group consisting of alkyl, cycloalkyl, alkenyl, cycloalkenyl, aryl, alkylaryl, and arylalkyl radical, each R′ containing from 1 to 20 carbon atoms; each R
2
is independently selected from the group consisting an alkyl, a cycloalkyl, an alkenyl, a cycloalkenyl, an aryl, an alkylaryl, or an arylalkyl, each member of this group containing from 1 to 20 carbon atoms; and optionally at least two R
2
moieties are joined together to from a ring having 4 to 6 carbon atoms; k is 0, 1, 2, 3.
There is also provided a catalyst system comprising:
Component A′ having the formula: (CpRn)R
1
(1−y)(CpRm)MY
2
wherein M, (CpRn), (CpRm), R, R
1
are as set forth above; and each Y is independently a phenoxide radical having the formula:
wherein A, D, R′, R
2
, m, n, k and y are as set forth above; and
Component B an aluminoxane. By “chelatable” is meant that the A and D groups on C and A′, respectively, have functional components that can attach by coordinate links, either intermolecularly (Component C) or intramolecularly (Component A′) to the transition metal atoms based catalyst center in such a way to form chelate rings.
There are further provided a polymerization process using these catalysts and the polyolefin so produced. The use of at least one of these catalysts provide a polymerization (e.g., gas phase fluidized process) whereby the final polymer produced has increased molecular weight as compared to polymerizing in the absence of the phenolic substituent and does so without a loss or reduction in catalyst activity during the polymerization.
DETAILED DESCRIPTION OF THE INVENTION
Catalyst System. The present invention provides a catalyst system comprising a combination of Components A, B, and C or a combination of Components A′ and B in which Component A′ is the reaction product of Components A and C. Optionally one or more of these components can be deposited on a support material using techniques known to those skilled in the catalyst art. Alternatively, one or more components of the catalyst system may be spray dried with or without a filler using techniques known to those skilled in the catalyst art (for example, see U.S. Pat. No. 5,672,669).
At all times, the individual catalyst system components, as well as the catalyst system once formed, need to be protected from oxygen and moisture since these are known poisons for the catalysts. Therefore, the reactions to prepare the catalyst system are performed in an oxygen and moisture free atmosphere and, where the catalyst system is recovered separately, it is recovered in an oxygen and moisture free atmosphere. Preferably, therefore, the reactions are performed in the presence of an inert dry gas such as, for example, nitrogen, argon, helium, a C
2
to C
8
alkane, or mixtures of these.
Component A. In the catalyst system of the invention Component A has the formula:
(CpRn)R
1
(1−y)(CpRm)MX
2
where M is a metal selected from the group consisting of Ti, Zr, and Hf; each (CpRn) and (CpRm) is independently a cyclopentadienyl or substituted cyclopentadienyl group bonded to M; each R is independently selected from the gro
Kao Sun-Chueh
Karol Frederick John
Choi Ling-Siu
Union Carbide Chemicals & Plastics Technology Corporation
Wu David W.
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