Deactivated and reactivated metallocene catalyst systems

Catalyst – solid sorbent – or support therefor: product or process – Catalyst or precursor therefor – Plural component system comprising a - group i to iv metal...

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502117, 502120, 502128, 526 90, 526119, B01J 3140, C08F 442

Patent

active

054749611

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

The present invention relates to metallocene catalyst systems for the polymerization of C.sub.2 -C.sub.10 -alkenes, obtainable by deactivating a preactivated metallocene catalyst system which contains, as active components, a metallocene complex of a metal of subgroup IV or V of the Periodic Table and an oligomeric alumoxane compound.
The present invention furthermore relates to metallocene catalyst systems obtainable by reactivating the deactivated metallocene systems, processes for the preparation of the deactivated and reactivated metallocene catalyst systems, their use for the preparation of polyalkenes, processes for the preparation of polyalkenes with the aid of these metallocene catalyst systems and the polyalkenes obtainable.
Since metallocene catalysts obtain optimum polymerization activity when they are preactivated with aluminum compounds, process engineering problems, for example blockage of the metering system due to premature polymerization, may occur during metering of the catalysts. This problem can be avoided by deactivating such catalyst systems, although the deactivation must be reversible.


SUMMARY OF THE INVENTION

It is an object of the present invention to deactivate preactivated metallocene catalyst systems and then to reactivate them.
We have found that this object is achieved, according to the invention, by the metallocene catalyst systems defined at the outset. We have also found processes for the preparation of the deactivated and reactivated metallocene catalyst systems, their use for the preparation of polyalkenes, processes for the preparation of polyalkenes with the aid of these metallocene catalyst systems and the polyalkenes obtainable.


DESCRIPTION OF PREFERRED EMBODIMENTS

Metallocene catalyst systems which are suitable for deactivation contain, among the active components, a complex of a metal of subgroup IV or V of the Periodic Table, in particular of titanium, zirconium, hafnium, vanadium, niobium or tantalum. Preferably used complexes are those in which the metal atom is bonded to unsaturated cyclic carbon atoms via .pi. bonds, for example cyclopentadienyl, fluorenyl or indenyl groups. Furthermore, in preferably used complexes, the metal atom may also be bonded to further ligands, in particular to fluorine, chlorine, bromine, iodine, hydrogen or C.sub.1 -C.sub.10 -alkyl, for example methyl, ethyl, propyl or butyl. Particularly suitable complexes contain, in particular, chlorine.
Merely by way of example, reference may be made here to EP-A 129 368, EP-A 407 870, EP-A 413 326, EP-A 399 347 and DE-A 39 29 693, in which suitable metallocene catalyst systems are described.
Metallocene catalyst systems which have proved to be preferable are those which contain, as active components,
a) a metallocene complex of the formula I ##STR1## where R.sup.1 to R.sup.3 and R.sup.5 to R.sup.7 are each hydrogen, C.sub.1 -C.sub.10 -alkyl, 5-membered to 7-membered cycloalkyl which in turn may carry a C.sub.1 -C.sub.6 -alkyl radical as a substituent, or C.sub.6 -C.sub.15 -aryl or arylalkyl, where two adjacent radicals R.sup.1 and R.sup.2, R.sup.2 and R.sup.3, R.sup.5 and R.sup.6 or R.sup.6 and R.sup.7 together may be a cyclic group of 4 to 15 carbon atoms, R.sup.4 and R.sup.8 are each hydrogen or C.sub.1 -C.sub.10 -alkyl, R.sup.9 is C.sub.1 -C.sub.10 -alkyl, C.sub.3 -C.sub.10 -cycloalkyl or C.sub.6 -C.sub.10 -aryl, M is titanium, zirconium, hafnium, vanadium, niobium or tantalum, Y is silicon, germanium, tin or carbon, X is hydrogen, fluorine, chlorine, bromine, iodine or C.sub.1 -C.sub.10 -alkyl and n is 0, 1 or 2, and
b) an open-chain or cyclic alumoxane compound of the formula II or III ##STR2## where R.sup.10 is C.sub.1 -C.sub.4 -alkyl and m is from 5 to 30.
Preferred metallocene complexes of the general formula I are those in which R.sup.1 and R.sup.5 are identical and are each hydrogen or C.sub.1 -C.sub.10 -alkyl, R.sup.4 and R.sup.8 are identical and are each hydrogen, methyl, ethyl, isopropyl or tert-butyl, R.sup.3 and R.sup.7 are each C.sub.1 -C.sub.

REFERENCES:
patent: 3173770 (1965-03-01), Thompson et al.
patent: 3202491 (1965-08-01), Maxwell et al.
patent: 4871375 (1989-10-01), Martischius et al.
patent: 4921920 (1990-05-01), Collomb-Ceccarini et al.
patent: 4931417 (1990-06-01), Miya et al.
patent: 4942147 (1990-07-01), Karol et al.
patent: 5037908 (1991-08-01), Tachikawa et al.

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