Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Reexamination Certificate
2002-10-24
2004-07-06
Choi, Ling-Siu (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Polymers from only ethylenic monomers or processes of...
C526S901000, C526S110000, C526S121000, C526S124300
Reexamination Certificate
active
06759492
ABSTRACT:
FIELD OF INVENTION
The present invention relates to a continuous gas phase polymerization process for producing polyethylene and interpolymers of ethylene and at least one other olefin comprising introducing into a polymerization medium ethylene or ethylene and other olefin(s), a Ziegler-Natta catalyst comprising at least one transition metal component selected from titanium, zirconium, hafnium, or mixtures thereof, a co-catalyst component, and at least one non-aromatic halogenated hydrocarbon(s) wherein at least one or more non-aromatic halogenated hydrocarbon(s) is added in a molar ratio of non-aromatic halogenated hydrocarbon(s) to the transition metal component of the Ziegler-Natta catalyst from 0.2:1 to about 3:1. More specifically, the present invention relates to a process to enhance the activity of a Ziegler-Natta catalyst by adding at least one non-aromatic halogenated hydrocarbon(s) wherein at least one or more non-aromatic halogenated hydrocarbon(s) is added in a molar ratio of non-aromatic halogenated hydrocarbon(s) to the transition metal component of the Ziegler-Natta catalyst in a range of 0.2:1 to about 3:1; wherein the catalyst activity is increased over the range as compared with the process conducted outside the range.
BACKGROUND OF INVENTION
The use of halogenated hydrocarbons with Ziegler-Natta catalysts for the production of polyethylene is disclosed in U.S. Pat. Nos. 5,863,995; 5,990,251; 4,657,998 and 3,354,139. In general, it is disclosed that the halogenated hydrocarbons may reduce the rate of ethane formation, control the molecular weight of the polyethylene, produce polyethylenes with broad molecular weight distributions, or provide other effects.
In U.S. Pat. No. 5,990,251 it is disclosed that halogenated hydrocarbons are used, in a polymerization process for producing polyethylene utilizing a titanium based Ziegler-Natta catalyst for increasing the catalyst activity in the polymerization. It is further stated that the amount of halogenated hydrocarbon must be present in a molar ratio of halogenated hydrocarbon to titanium of the Ziegler-Natta catalyst from 0.001 to 0.15. Furthermore, it is disclosed that when the molar ratio of halogenated hydrocarbon to titanium is too high, the activity of the catalyst is not appreciably modified or is substantially reduced in a continuous polymerization process. It is also stated that when the molar ratio is too low, the catalyst activity is not substantially modified.
In U.S. Pat. No. 5,863,995, there is reference to catalytic activity in a process for producing polyethylene using a titanium containing Ziegler-Natta catalyst and a halogenated hydrocarbon in a specified amount. The patent states that the halogenated hydrocarbon is present in a molar ratio of halogenated hydrocarbon to the titanium in the catalyst of 0.01 to 1.8. It is further stated that the specified quantity of halogenated hydrocarbon results in no substantial variation of the average activity of the catalyst.
In U.S. Pat. No. 3,354,139, there is disclosed the use of halogenated hydrocarbons with a Ziegler-Natta catalyst to control the molecular weight of polyethylene prepared in a solution or slurry polymerization process.
In U.S. Pat. No. 4,657,998, there is disclosed a catalyst system comprising a titanium containing catalyst component, isoprenylaluminum and a halohydrocarbon for the production of polyethylene having a broad molecular weight distribution.
In this invention, applicants have unexpectedly found that in a continuous gas phase polymerization process for producing polyethylene and interpolymers of ethylene and at least one other olefin comprising introducing into a polymerization medium the ethylene or ethylene and at least one other olefin, a Ziegler-Natta catalyst comprising at least one transition metal component selected from titanium, zirconium, hafnium, or mixtures thereof, a co-catalyst component, and at least one non-aromatic halogenated hydrocarbon(s) wherein at least one or more non-aromatic halogenated hydrocarbon(s) is added in a molar ratio of non-aromatic halogenated hydrocarbon(s) to the transition metal component of the Ziegler-Natta catalyst in a range of about 0.2:1 to about 3:1, the activity of the catalyst is increased as compared with the process conducted outside the range. Applicants have also unexpectedly found that the increase in activity can be preceded by an initial decrease in catalyst activity for a period of time when the continuous process is transitioned to the molar ratio range.
SUMMARY OF THE INVENTION
In a first embodiment of this invention, a process for increasing catalyst activity in a continuous gas phase process for polymerizing ethylene or ethylene and at least one or more other olefin(s) is provided. The process comprises contacting, under polymerization conditions, the ethylene or ethylene and at least one or more other olefin(s) with a Ziegler-Natta catalyst comprising at least one transition metal component selected from the group consisting of titanium, zirconium, hafnium and mixtures thereof and a co-catalyst component, and at least one or more non-aromatic halogenated hydrocarbon(s) wherein the at least one or more non-aromatic halogenated hydrocarbon(s) is added in a molar ratio of non-aromatic halogenated hydrocarbon(s) to the transition metal component of the Ziegler-Natta catalyst from 0.2:1 to about 3:1.
In another embodiment of this invention, a process for increasing catalyst activity in a continuous gas phase process for polymerizing ethylene or ethylene and at least one or more other olefin(s) is provided. The process comprises contacting, under polymerization conditions, the ethylene or ethylene and at least one or more other olefin(s) with a Ziegler-Natta catalyst comprising at least one transition metal component selected from the group consisting of titanium, zirconium, hafnium and mixtures thereof, a co-catalyst component, and at least one or more non-aromatic halogenated hydrocarbon(s) wherein at least one or more non-aromatic halogenated hydrocarbon(s) is added in a molar ratio of non-aromatic halogenated hydrocarbon(s) to the transition metal component of the Ziegler-Natta catalyst in a range of 0.2:1 to about 3:1; wherein the catalyst activity is increased over the range as compared with the process conducted outside the range.
These objects, and other objects, will become more apparent to others with ordinary skill in the art after reading this disclosure.
DETAILED DESCRIPTION OF THE INVENTION
In the two embodiments of this invention, a process is provided for increasing catalyst activity in a continuous gas phase process for polymerizing ethylene or ethylene and at least one or more other olefin(s), the process comprising contacting, under polymerization conditions, the ethylene or ethylene and at least one or more other olefin(s) with a Ziegler-Natta catalyst comprising at least one transition metal component selected from the group consisting of titanium, zirconium, hafnium and mixtures thereof, a co-catalyst component, and at least one or more non-aromatic halogenated hydrocarbon(s); wherein at least one or more non-aromatic halogenated hydrocarbon(s) is added in a molar ratio of non-aromatic halogenated hydrocarbon(s) to the transition metal component of the Ziegler-Natta catalyst from 0.2:1 to about 3:1.
The continuous gas phase polymerization process for producing ethylene and interpolymers of ethylene and at least one other olefin may be carried out using any suitable continuous gas phase polymerization process. These types of processes and means for operating the polymerization reactors are well known and completely described in U.S. Pat. Nos. 3,709,853; 4,003,712; 4,011,382; 4,012,573; 4,302,566; 4,543,399; 4,882,400; 5,352,749 and 5,541,270. These patents disclose gas phase polymerization processes wherein the polymerization zone is either mechanically agitated or fluidized by the continuous flow of the gaseous monomer and diluent. The entire contents of these patents are incorporated herein by reference.
The polymerization process of the present inv
Dooley Kenneth Alan
Farrer Don Kent
Moore Glenn Edward
Noble Larry Allen
Choi Ling-Siu
Eastman Chemical Company
Graves, Jr. Bernard J.
Owen Steven A.
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