Propylene polymerization process

Details Propylene polymerization process Propylene polymerization process

2000-06-22

2003-06-03

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...

C526S064000, C526S096000, C526S098000, C526S099000, C526S137000, C526S143000, C526S126000, C526S170000, C526S348000, C526S943000, C526S156000

Reexamination Certificate

active

06573344

ABSTRACT:

FIELD OF THE INVENTION
This invention is related to the field of propylene polymerization processes.
BACKGROUND OF THE INVENTION
The production of propylene polymers is a multi-million dollar business. This business produces billions of pounds of propylene polymers each year. Millions of dollars have been spent on developing technologies that can add value to this business.
One of these technologies is called metallocene catalyst technology. Metallocene catalysts have been known since about 1958. However, their low productivity did not allow them to be commercialized. About 1974, it was discovered that contacting one part water with one part trimethylaluminum to form methyl aluminoxane, and then contacting such methyl aluminoxane with a metallocene compound, formed a metallocene catalyst that had greater activity. However, it was soon realized that large amounts of expensive methyl aluminoxane were needed to form an active metallocene catalyst. This has been a significant impediment to the commercialization of metallocene catalysts.
Fluoro organic borate compounds have been used in place of large amounts of methyl aluminoxane. However, this is not satisfactory, since borate compounds are very sensitive to poisons and decomposition, and can also be very expensive.
It should also be noted that having a heterogeneous catalyst is important. This is because heterogeneous catalysts are required for most modern commercial polymerization processes. Furthermore, heterogeneous catalysts can lead to the formation of substantially uniform polymer particles that have a high bulk density. These types of substantially uniform particles are desirable because they improve the efficiency of polymer production and transportation. Efforts have been made to produce heterogeneous metallocene catalysts; however, these catalysts have not been entirely satisfactory.
There is a need in the propylene polymer industry to activate metallocenes more efficiently and economically.
An object of this invention is to provide a process to polymerize propylene to produce a propylene polymer.
Another object of this invention is to provide the propylene polymer produced by the process.
These objects, and other objects, will become more apparent to those with ordinary skill in the art after reading this disclosure.
SUMMARY OF THE INVENTION
In accordance with an embodiment of this invention, a process is provided to produce a propylene polymer. The term “propylene polymer” means both a propylene homopolymer and a propylene copolymer. The process comprises contacting at least one organometal compound, at least one organoaluminum compound, at least one treated solid oxide compound, propylene, and ethylene in a polymerization zone under polymerization conditions to produce a propylene polymer;
wherein the organometal compound has the following general formula:
(X
1
)(X
2
)(X
3
)(X
4
)M
1
wherein M
1
is selected from the group consisting of titanium, zirconium, and hafnium;
wherein (X
1
) and (X
2
) are independently selected from the group consisting of cyclopentadienyls, indenyls, fluorenyls, substituted cyclopentadienyls, substituted indenyls, and substituted fluorenyls;
wherein substituents on the substituted cyclopentadienyls, substituted indenyls, and substituted fluorenyls of (X
1
) and (X
2
) are selected from the group consisting of aliphatic groups, cyclic groups, combinations of aliphatic and cyclic groups, silyl groups, alkyl halide groups, halides, organometallic groups, phosphorus groups, nitrogen groups, silicon, phosphorus, boron, germanium, and hydrogen;
wherein at least one substituent on (X
1
) and (X
2
) is a bridging group which connects (X
1
) and (X
2
);
wherein (X
3
) and (X
4
) are independently selected from the group consisting of halides, aliphatic groups, substituted aliphatic groups, cyclic groups, substituted cyclic groups, combinations of aliphatic groups and cyclic groups, combinations of substituted aliphatic groups and cyclic groups, combinations of aliphatic groups and substituted cyclic groups, combinations of substituted aliphatic groups and substituted cyclic groups, amido groups, substituted amido groups, phosphido groups, substituted phosphido groups, alkyloxide groups, substituted alkyloxide groups, aryloxide groups, substituted aryloxide groups, organometallic groups, and substituted organometallic groups; and
wherein the organoaluminum compound has the following general formula:
Al(X
5
)
n
(X
6
)
3−n
wherein (X
5
) is a hydrocarbyl having from 1-20 carbon atoms;
wherein (X
6
) is a halide, hydride, or alkoxide;
wherein “n” is a number from 1 to 3 inclusive; and
wherein the treated solid oxide compound is produced by a process comprising: a) contacting at least one solid oxide compound with at least one electron-withdrawing anion source compound; and b) calcining the solid oxide compound before, during, or after contacting the electron-withdrawing anion source compound to produce the treated solid oxide compound.
In accordance with another embodiment of this invention, the propylene polymer is provided.
DETAILED DESCRIPTION OF THE INVENTION
In this invention, a process to produce a propylene polymer is provided. The process comprises contacting at least one organometal compound, at least one organoaluminum compound, at least one treated solid oxide compound, propylene, and ethylene in a polymerization zone under polymerization conditions to produce the propylene polymer.
Organometal compounds used in this invention have the following general formula:
(X
1
)(X
2
)(X
3
)(X
4
)M
1
In this formula, M
1
is selected from the group consisting of titanium, zirconium, and hafnium. Currently, it is most preferred when M
1
is zirconium.
In this formula, (X
1
) and (X
2
) are independently selected from the group consisting of cyclopentadienyls, indenyls, fluorenyls, substituted cyclopentadienyls, substituted indenyls, such as, for example, tetrahydroindenyls, and substituted fluorenyls, such as, for example, octahydrofluorenyls.
Substituents on the substituted cyclopentadienyls, substituted indenyls, and substituted fluorenyls of (X
1
) and (X
2
) can be selected independently from the group consisting of aliphatic groups, cyclic groups, combinations of aliphatic and cyclic groups, silyl groups, alkyl halide groups, halides, organometallic groups, phosphorus groups, nitrogen groups, silicon, phosphorus, boron, germanium, and hydrogen, as long as these groups do not substantially, and adversely, affect the polymerization activity of the catalyst composition.
Suitable examples of aliphatic groups are hydrocarbyls, such as, for example, paraffins and olefins. Suitable examples of cyclic groups are cycloparaffins, cycloolefins, cycloacetylenes, and arenes. Substituted silyl groups include, but are not limited to, alkylsilyl groups where each alkyl group contains from 1 to about 12 carbon atoms, arylsilyl groups, and arylalkylsilyl groups. Suitable alkyl halide groups have alkyl groups with 1 to about 12 carbon atoms. Suitable organometallic groups include, but are not limited to, substituted silyl derivatives, substituted tin groups, substituted germanium groups, and substituted boron groups.
Suitable examples of such substituents are methyl, ethyl, propyl, butyl, tert-butyl, isobutyl, amyl, isoamyl, hexyl, cyclohexyl, heptyl, octyl, nonyl, decyl, dodecyl, 2-ethylhexyl, pentenyl, butenyl, phenyl, chloro, bromo, iodo, trimethylsilyl, and phenyloctylsilyl.
The organometal compound must have at least one substituent on (X
1
) and (X
2
) which serves as a bridging group which connects (X
1
) and (X
2
). This bridging group consists of one, two, or three connecting atoms which also can have substituents selected from the group consisting of aliphatic groups, cyclic groups, combinations of aliphatic and cyclic groups, silyl groups, alkyl halide groups, halides, and organometallic groups as long as the bridging group does not substantially, and adversely, affect the activity of the catalyst composition. The connecting atoms are selected from the group of carbon, silicon, germanium, tin, nit

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