Polymerization catalysts and process therefor

Details Polymerization catalysts and process therefor Polymerization catalysts and process therefor

2000-07-07

2002-06-04

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...

C526S171000, C526S172000, C526S348600, C502S155000

Reexamination Certificate

active

06399725

ABSTRACT:

BACKGROUND
This invention relates to homopolymerization of mono-1-olefin monomers, such as ethylene and propylene, and copolymerization of a mono-1-olefin monomers, such as ethylene and propylene, with at least one higher alpha-olefin comonomer.
It is well known that mono-1-olefins, such as ethylene and propylene, can be polymerized with catalyst systems employing transition metals such as titanium, vanadium, chromium, nickel and/or other metals, either unsupported or on a support such as alumina, silica, titania, and other refractory metals. Supported polymerization catalyst systems frequently are used with a cocatalyst, such as alkyl boron and/or alkyl aluminum compounds. Organometallic catalyst systems, i.e., Ziegler-Natta-type catalyst systems usually are unsupported and frequently are used with a cocatalyst, such as methylaluminoxane.
It is also well-known that, while no polymer production process is easy, slurry, or loop, polymerization processes are relatively much more commercially desirable than other polymerization processes. Furthermore, the type of polymerization process used can have an effect on the resultant polymer. For example, higher reactor temperatures can result in low catalyst activity and productivity, as well as a lower molecular weight polymer product. Higher reactor pressures also can decrease the amount of desirable branching in the resultant polymer.
Most polymer products made in slurry processes, especially those polymer products made using supported chromium catalyst systems, have a broader molecular weight distribution and, therefore, the polymer product is much easier to process into a final product. Polymers made by other processes, such as, for example, higher temperature and/or higher pressure solution processes, can produce polymers having a narrow molecular weight distribution; these polymers can be much more difficult to process into an article of manufacture.
Unfortunately, many homogeneous organometallic catalyst systems have low activity, high consumption of very costly cocatalysts, like methylaluminoxane (MAO), and can produce low molecular weight polymers with a narrow molecular weight distribution. Furthermore, even though MAO can be necessary to produce a polymer with desired characteristics, an excess of MAO can result in decreased catalyst system activity. Additionally, these types of homogeneous catalyst systems preferably are used only in solution or gas phase polymerization processes.
SUMMARY OF THE INVENTION
It is an object of this invention to provide novel catalyst systems useful for mono-1-olefin polymerization.
It is another object of this invention to provide catalyst systems which are relatively simple to make, have increased activity and increased productivity.
It is a further object of this invention to provide catalyst systems which have reduced cocatalyst consumption.
It is still another object of this invention to provide an improved polymerization process.
It is yet another object of this invention to provide homopolymers of mono-1-olefins and copolymers of at least two different mono-1-olefin(s) that can be processed easily, as indicated by increased branching and a broad molecular weight distribution.
It is still another object of this invention to provide homopolymers of mono-1-olefins and copolymers of at least two different mono-1-olefin(s) that have decreased molecular weight.
In accordance with this invention catalyst systems comprising 2-pyridine carboxaldimine nickel complexes which further comprise additional ligands selected from the group consisting of &bgr;-dikenotates, halogens and mixtures thereof and methylaluminoxane are provided. Processes to make these catalyst systems also are provided.
In accordance with another embodiment of this invention, slurry polymerization processes comprising contacting ethylene, and optionally one or more higher alpha-olefins, in a reaction zone with catalyst systems comprising 2-pyridinecarboxaldimine nickel complexes which further comprise additional ligands selected from the group consisting of &bgr;-dikenotates, halogens and mixtures thereof in the presence of methylaluminoxane are provided.
In accordance with yet another embodiment of this invention, homopolymers of ethylene and copolymers of ethylene and one or more higher alpha-olefins which can be characterized as having low molecular weight, increased branching and a broad molecular weight distribution, are provided.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Catalyst Systems
Catalyst systems of this invention can be characterized as 2-pyridine-carboxaldimine nickel complexes comprising additional ligands selected from the group consisting of &bgr;-diketonates, halogens and mixtures thereof having a general formula as shown below in Compound I,
wherein R′ and R″ can be the same or different and are selected from the group consisting of branched and/or linear alkyl or aromatic groups having from about 1 to about 10, preferably from about 1 to about 8, carbon atoms per alkyl group and R′ or R″ can be in any position on the aromatic ring; and
R can be the same or different and is selected from the group consisting of hydrogen and linear, branched, cyclic, bridging, aromatic, and/or aliphatic hydrocarbons, having from about 1 to about 70 carbon atoms per radical group.
R′ and R″ substituents on the aromatic and pyridine rings of the 2-pyridinecarboxaldimine nickel complex can be the same or different, and are selected from the group consisting of hydrogen and branched or linear, aliphatic or aromatic groups having from about 1 to about 8 carbon atoms per alkyl group. R′ and R″ groups having more than about 8 carbon atoms per group can result in a catalyst system with lower activity and/or productivity. While not wishing to be bound by theory, it is believed that larger substituent groups can cause steric hindrance in the catalyst system, thereby which can decrease catalyst system activity and/or productivity. Exemplary alkyl substituents are selected from the group consisting of methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, phenyl groups, fused phenyl groups (such that the pyridine group and the substituent taken together form a quinoline group), and mixtures of two or more thereof. Preferably, the R′ or R″ substituent is an electron-donating species, selected from the group consisting of linear or branched aliphatic or fused aromatic groups having from about 1 to about 15 carbon atoms per group. Most preferably, the R″ groups are both the same and are selected from the group consisting of methyl and isopropyl and the R′ group is selected from the group consisting of hydrogen, methyl, or fused phenyl, due to commercial availability and ease of synthesis of the ligand.
The R′ and R″ groups can be in any position, i.e., from 2 to 6, on the aromatic ring. Preferably, the R′ group is either in the 3 and/or 6 position, due to ease of synthesis. Most preferably, for best catalytic activity and productivity, the R′ group is on the 6 position on the aromatic ring. Preferably, the R″ groups, which can be the same or different, are either in the 2 and/or 6 position, due to ease of synthesis. Most preferably, for best catalytic activity and productivity, both R″ groups are the same and are in the 2 and 6 positions on the aromatic ring.
The R substituent is selected from the group consisting of hydrogen and branched, linear, cyclic, aromatic or aliphatic radicals having from about 1 to about 70 carbon atoms per radical. Further, the R substituent can be linked, or joined, to the pyridine group to form a ring. While not wishing to be bound by theory, it is believed that radicals having more than 70 carbon atoms can add to the steric hindrance of the catalyst systems and hinder catalyst activity and productivity. Preferably, the R substituent group is selected from the group consisting of hydrogen and branched, linear, cyclic, aromatic or aliphatic radicals having from about 1 to about 20 carbon atoms per

Affiliated with

Also associated with

Rating

Polymerization catalysts and process therefor does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Polymerization catalysts and process therefor, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Polymerization catalysts and process therefor will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2967249