Catalyst for the production of olefin polymers

Details Catalyst for the production of olefin polymers Catalyst for the production of olefin polymers

2000-01-13

2002-04-30

Seaman, D. Margaret (Department: 1612)

Organic compounds -- part of the class 532-570 series

Organic compounds

Heterocyclic carbon compounds containing a hetero ring...

C546S002000, C546S179000, C546S261000

Reexamination Certificate

active

06380390

ABSTRACT:

The invention relates to a family of novel catalyst compositions for the production of olefin polymers, such as polymers of ethylene, higher alpha-olefins, dienes, and mixtures thereof.
BACKGROUND
A variety of metallocenes and single site-like catalysts have been developed to prepare olefin polymers. Metallocenes are organometallic coordination complexes containing one or more &pgr;-bonded moieties (i.e., cyclopentadienyl groups) in association with a metal atom from Groups IIIB to VIII or the Lanthanide series of the Periodic Table of Elements. Catalyst compositions containing metallocenes and single site-like catalysts are highly useful in the preparation of polyolefins, producing relatively homogeneous copolymers at excellent polymerization rates while allowing one to tailor closely the final properties of the polymer as desired.
U.S. Pat. No. 5,280,000 to Kakugo et al. discloses a catalyst composition for the polymerization of high molecular weight olefins consisting of a transition metal compound of the formula M(R)
l
(OR′)
m
X
n
−(l+m) (wherein M is a transition metal atom, R and R′ are hydrocarbyl groups of 1-20 carbons, X is a halogen, l≧0, m>0, n−(l+m)≧0, and n is the valence of the transition metal), an aluminoxane, and optionally an organic compound having at least two hydroxyl groups and optionally an aryl group.
A new single site-like, olefin polymerization catalyst composition is described herein having good polymerization activity and productivity, which is easily and inexpensively prepared. The catalyst composition comprises a bis(hydroxy aromatic nitrogen ligand) transition metal catalyst precursor that is activated with a cocatalyst such as an aluminoxane.
SUMMARY OF THE INVENTION
The invention provides catalyst precursor having a formula selected from the group consisting of:
and
wherein M is a metal selected from the group consisting of Group IIIB to VIII and Lanthanide series elements; each X is a monovalent or bivalent anion; o is 0,1, 2, or 3 depending on the valence of M; each R
1
, R
2
, R
3
, and R
4
is a hydrocarbon group containing 1 to 20 carbon atoms and two or more adjacent R
1
, R
2
, R
3
, or R
4
groups may be joined to form an aliphatic, aromatic, or heterocyclic ring; Y is a bivalent bridging group or a bond; each m is independently from 0 to 4; and n is 0 or 1.
The invention also provides a catalyst composition comprising the above catalyst precursor and an activating cocatalyst.
The invention further provides a process for producing an olefin polymer, which comprises contacting an olefin monomer under polymerization conditions with the above catalyst composition, as well as olefin polymers, such as ethylene polymers, produced by this process.
DETAILED DESCRIPTION OF THE INVENTION
The catalyst precursor has one of the following formulas:
or
In the above formula, M is a metal selected from the group consisting of Group IIIB to VIII and Lanthanide series elements, preferably titanium, zirconium, or hafnium, most preferably zirconium. Each X is a monovalent or bivalent anion, preferably selected from the group consisting of hydrogen, aryl, alkyl, alkenyl, alkylaryl, arylalkyl, or hydrocarboxy radicals having 1-20 carbon atoms, —NR
2
, —OR, or RCO
2
— wherein R is a hydrocarbon radical having 1 to 20 carbon atoms, and halogens, and o is 0, 1, 2, or 3 depending on the valence of M. More preferably X is a halogen. Each R
1
, R
2
, R
3
, and R
4
is a hydrocarbon group containing 1 to 20 carbon atoms and two or more adjacent R
1
, R
2
, R
3
, or R
4
groups may be joined to form an aliphatic, aromatic, or heterocyclic ring. Preferably, R
1
, R
2
, R
3
, and R
4
are methyl or ethyl groups. Y is a bivalent bridging group or a bond, and is optional. When Y is present, Y is preferably one or more methylene groups. Finally, each m is independently from 0 to 4, preferably 0, and n is 0 or 1.
In a preferred embodiment of the invention, the catalyst precursor has the formula:
In another preferred embodiment of the invention the catalyst precursor has the formula:
The catalyst precursor may be prepared by any synthesis method, and the method of making the catalyst precursor is not critical to the invention. One useful method of making the catalyst precursor is by reacting a hydroxy aromatic nitrogen compound, which compounds are commercially available, with a metallic deprotonating agent such as an alkyllithium compound in an organic solvent to form the metal salt of the hydroxy aromatic nitrogen compound. The resulting salt may then be reacted with a salt of the desired transition metal, preferably a transition metal halide (i.e., zirconium tetrachloride for a zirconium-containing catalyst precursor) to form the bis(hydroxy aromatic nitrogen ligand) transition metal catalyst precursor. The catalyst precursor may be isolated by methods well known in the art.
The activating cocatalyst is capable of activating the catalyst precursor. Preferably, the activating cocatalyst is one of the following: (a) branched or cyclic oligomeric poly(hydrocarbylaluminum oxide)s which contain repeating units of the general formula —(Al(R*)O)—, where R* is hydrogen, an alkyl radical containing from 1 to about 12 carbon atoms, or an aryl radical such as a substituted or unsubstituted phenyl or naphthyl group; (b) ionic salts of the general formula [A
+
][BR**
4
—], where A+ is a cationic Lewis or Bronsted acid capable of abstracting an alkyl, halogen, or hydrogen from the metallocene catalysts, B is boron, and R** is a substituted aromatic hydrocarbon, preferably a perfluorophenyl radical; (c) boron alkyls of the general formula BR**
3
, where R** is as defined above; or mixtures thereof.
Preferably, the activating cocatalyst is a branched or cyclic oligomeric poly(hydrocarbylaluminum oxide) or a boron alkyl. More preferably, the activating cocatalyst is an aluminoxane such as methylaluminoxane (MAO) or modified methylaluminoxane (MMAO), or a boron alkyl.
Aluminoxanes are well known in the art and comprise oligomeric linear alkyl aluminoxanes represented by the formula:
and oligomeric cyclic alkyl aluminoxanes of the formula:
wherein s is 1-40, preferably 10-20; p is 3-40, preferably 3-20; and R*** is an alkyl group containing 1 to 12 carbon atoms, preferably methyl.
Aluminoxanes may be prepared in a variety of ways. Generally, a mixture of linear and cyclic aluminoxanes is obtained in the preparation of aluminoxanes from, for example, trimethylaluminum and water. For example, an aluminum alkyl may be treated with water in the form of a moist solvent. Alternatively, an aluminum alkyl, such as trimethylaluminum, may be contacted with a hydrated salt, such as hydrated ferrous sulfate. The latter method comprises treating a dilute solution of trimethylaluminum in, for example, toluene with a suspension of ferrous sulfate heptahydrate. It is also possible to form methylaluminoxanes by the reaction of a tetraalkyldialuminoxane containing C
2
or higher alkyl groups with an amount of trimethylaluminum that is less than a stoichiometric excess. The synthesis of methylaluminoxanes may also be achieved by the reaction of a trialkyl aluminum compound or a tetraalkyldialunminoxane containing C
2
or higher alkyl groups with water to form a polyalkyl aluminoxane, which is then reacted with trimethylaluminum. Further modified methylaluminoxanes, which contain both methyl groups and higher alkyl groups, i.e., isobutyl groups, may be synthesized by the reaction of a polyalkyl aluminoxane containing C
2
or higher alkyl groups with trimethylaluminum and then with water as disclosed in, for example, U.S. Pat. No. 5,041,584.
When the activating cocatalyst is a branched or cyclic oligomeric poly(hydrocarbylaluminum oxide), the mole ratio of aluminum atoms contained in the poly(hydrocarbylaluminum oxide) to total metal atoms contained in the catalyst precursor is generally in the range of from about 2:1 to about 100,000:1, preferably in the range of from about 10:1 to about 10,000:1, and most preferably in the rang

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