Catalyst – solid sorbent – or support therefor: product or process – Catalyst or precursor therefor – Plural component system comprising a - group i to iv metal...
Reexamination Certificate
1999-12-20
2002-05-07
Wu, David W. (Department: 1713)
Catalyst, solid sorbent, or support therefor: product or process
Catalyst or precursor therefor
Plural component system comprising a - group i to iv metal...
C502S113000, C502S117000, C502S118000, C502S152000, C502S155000, C526S160000, C526S161000, C526S943000
Reexamination Certificate
active
06383968
ABSTRACT:
The invention relates to a process for the polymerisation of olefins with a catalyst comprising a metallocene compound according to the formula
wherein the symbols have the following meanings:
M a reduced transition metal selected from group 4, 5 or 6 of the Periodic Table of Elements;
X a multidentate monoanionic ligand represented by the formula: (Ar—R
t
—)
s
Y(—R
t
—DR′
n
)
q
;
Y a cyclopentadienyl, amido (—NR′—), or phosphido group (—PR′—), which is bonded to the reduced transition metal M;
R at least one member selected from the group consisting of (i) a connecting group between the Y group and the DR′
n
group and (ii) a connecting group between the Y group and the Ar group, wherein when the ligand X contains more than one R group, the R groups can be identical to or different from each other;
D an electron-donating hetero atom selected from group 15 or 16 of the Periodic Table of Elements;
R′ a substituent selected from the group consisting of a hydrogen, hydrocarbon radical and hetero atom-containing moiety, except that R′ cannot be hydrogen when R′ is directly bonded to the electron-donating hetero atom D, wherein when the multidentate monoanionic ligand X contains more than one substituent R′, the substituents R′ can be identical or different from each other;
Ar an electron-donating aryl group;
L a monoanionic ligand bonded to the reduced transition metal M;
K a neutral or anionic ligand bonded to the reduced transition metal M, wherein when the metallocene compound contains more than one ligand K, the ligands K can be identical or different from each other;
m is the number of K ligands, wherein when the K ligand is an anionic ligand m is 0 for M
3+
, m is 1 for M
4+
, and m is 2 for M
5+
, and when K is a neutral ligand m increases by one for each neutral K ligand;
n the number of the R′ groups bonded to the electron-donating hetero atom D, wherein when D is selected from group 15 of the Periodic Table of Elements n is 2, and when D is selected from group 16 of the Periodic Table of Elements n is 1;
q,s q and s are the number of (—R
t
—DR′
n
) groups and (Ar—R
t
) groups bonded to group Y, respectively, wherein q+s is an integer not less than 1; and
t the number of R groups connecting each of (i) the Y and Ar groups and (ii) the Y and DR′
n
groups, wherein t is selected independently as 0 or 1, and an aluminoxane.
Such a process is known from WO-96/13529.
In this patent application it is described that polyolefins can be polymerised with a catalyst containing a metallocene compound and an aluminoxane.
We have now discovered that when during polymerisation a catalyst is used comprising an aluminoxane comprising 0.5 to 15 mol % trialkylaluminium the catalyst activity is substantially higher when compared with a catalyst system comprising a standard aluminoxane comprising about 30 mol % trialkylaluminium.
This aluminoxane must be combined with a metallocene compound with a monoanionic ligand L which is bonded to the reduced transition metal M with a sigma bond, at least one L being a group comprising an element from group 14, 15 or 16 of the Periodic Table of Elements. Aluminoxanes with a lower amount of trialkylaluminium are known.
They are described for instance in WO-97/43320.
In WO-97/43320 is not described or suggested that because of using an aluminoxane comprising 0.5 to 15 mol % trialkylaluminium during polymerisation catalysts with a good activity are obtained.
Aluminoxanes which are substantially free of trialkylaluminium are known from WO 97/23288.
A disadvantage of the use of an aluminoxane which is substantially free of trialkylaluminium is that the use of this cocatalyst does not give a high activity catalyst system when combined with a metallocene compound according to formula (I).
The aluminoxane used in the process according to the invention comprises preferably 1-12 mol % trialkylaluminium and more preferably 6 to 10 mol % trialkylaluminium.
In the aluminoxane used according to the invention is preferably methylaluminoxane and the trialkylaluminium is trimethylaluminium.
The aluminoxane according to the invention can for instance be prepared by treating a standard aluminoxane, containing about 30 mol % TMA, under a pressure of 0.1 to 1000 Pa during 2-5 hours at a temperature between 45-150° C. The temperature is preferably between 80 and 140° C. The pressure is preferably between 1 and 100 Pa. According to this method an aluminoxane is formed with 7-9 mol % alkylaluminium. This preparation method is preferably used, because the aluminoxane obtained according to this method has a good solubility in toluene. This is an advantage when the aluminoxane according to the invention is dosed to the polymerisation reactor in toluene and is also an advantage during catalyst preparation in toluene.
The metallocene compound according to formula I is described for instance in WO-A-96/13529.
Various components of the metallocene compound are discussed below in more detail.
(a) The Transition Metal (M)
The transition metal in the complex is selected from groups 4-6 of the Periodic Table of Elements. As referred to herein, all references to the Periodic Table of Elements mean the version set forth in the new IUPAC notation found on the inside of the cover of the Handbook of Chemistry and Physics, 70th edition, 1989/1990, the complete disclosure of which is incorporated herein by reference.
The transition metal is present in reduced form in the complex, which means that the transition metal is in a reduced oxidation state. As referred to herein, “reduced oxidation state” means an oxidation state which is greater than zero but lower than the highest possible oxidation state of the metal (for example, the reduced oxidation state is at most M
3+
for a transition metal of group 4, at most M
4+
for a transition metal of group 5 and at most M
5+
for a transition metal of group 6).
(b) The X Ligand
The X ligand is a multidentate monoanionic ligand represented by the formula: (Ar—R
t
—)
s
Y(—R
t
—DR′
n
)
q
.
As referred to herein, a multidentate monoanionic ligand is bonded with a covalent bond to the reduced transition metal (M) at one site (the anionic site, Y) and is bonded either (i) with a coordinate bond to the transition metal at one other site (bidentate) or (ii) with a plurality of coordinate bonds at several other sites (tridentate, tetradentate, etc.). Such coordinate bonding can take place, for example, via the D heteroatom or Ar group(s). Examples of tridentate monoanionic ligands include, without limitation, Y—R
t
—DR′
n−1
—R
t
—DR′
n
and Y(—R—DR′
n
)
2
. It is noted, however, that heteroatom(s) or aryl substituent(s) can be present on the Y group without coordinately bonding to the reduced transition metal M, so long as at least one coordinate bond is formed between an electron-donating group D or an electron donating Ar group and the reduced transition metal M.
R represents a connecting or bridging group between the DR′
n
and Y, and/or between the electron-donating aryl (Ar) group and Y. Since R is optional, “t” can be zero. The R group is discussed below in paragraph (d) in more detail.
(c) The Y Group
The Y group of the multidentate monoanionic ligand (X) is preferably a cyclopentadienyl, amido (—NR′—), or phosphido (—PR′—) group.
Most preferably, the Y group is a cyclopentadienyl ligand (Cp group). As referred to herein, the term cyclopentadienyl group encompasses substituted cyclopentadienyl groups such as indenyl, fluorenyl, and benzoindenyl groups, and other polycyclic aromatics containing at least one 5-member dienyl ring, so long as at least one of the substituents of the Cp group is an R
t
—DR′
n
group or R
t
—Ar group that replaces one of the hydrogens bonded to the five-member ring of the Cp group via an exocyclic substitution.
Examples of a multidentate monoanionic ligand with a Cp group as the Y group (or ligand) include the following (with the (—R
t
—DR′
n
) or (Ar—R
t
—) su
Kranenburg Mirko
Meijers Ramon H. A. M.
Van Tol Maurits F. H.
DSM N.V.
Harlan R.
Wu David W.
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