Supported metallocene catalyst systems

Supported catalyst systems are obtainable by a) application of a mixture of PA1 A) at least one metallocene complex and PA1 B) at elast one metal compound PA1 to a carrier which, if required, may have been pretreated, and PA1 b) subsequent activation by reaction with a solution or suspension of a compound forming metallocenium ions.

The present invention relates to supported catalyst systems obtainable by 
a) application of a mixture of 
A) at least one metallocene complex of the formula I 
##STR1## 
where M is titanium, zirconium, hafnium, vanadium, niobium or tantalum, 
X is fluorine, chlorine, bromine, iodine, hydrogen, C.sub.1 -C.sub.10 
-alkyl, C.sub.6 -C.sub.15 -aryl or --OR.sup.5, 
R.sup.5 is C.sub.1 -C.sub.10 -alkyl, C.sub.6 -C.sub.15 -aryl, alkylaryl, 
arylalkyl, fluoroalkyl or fluoroaryl, where each alkyl radical is of 1 to 
10 carbon atoms and each aryl radical is of 6 to 20 carbon atoms, 
R.sup.1 to R.sup.4 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.10 
-alkyl as a substituent, C.sub.6 -C.sub.15 -aryl or arylalkyl, where two 
neighboring radicals together may furthermore form a cyclic group of 4 to 
15 carbon atoms, or Si(R.sup.6).sub.3, 
R.sup.6 is C.sub.1 -C.sub.10 -alkyl, C.sub.6 -C.sub.15 -aryl or C.sub.3 
-C.sub.10 -cycloalkyl, 
G is silicon, germanium, tin or carbon, 
R.sup.7 is hydrogen, C.sub.1 -C.sub.10 -alkyl, C.sub.3 -C.sub.10 
-cycloalkyl or C.sub.6 -C.sub.15 -aryl, 
n is 1, 2, 3 or 4, 
E is --O--, --S--, &lt;NR.sup.8 or &lt;PR.sup.8, 
R.sup.8 is C.sub.1 -C.sub.10 -alkyl, C.sub.3 -C.sub.10 -cycloalkyl, C.sub.6 
-C.sub.15 -aryl, alkylaryl or Si(R.sup.9).sub.3 and 
R.sup.9 is C.sub.1 -C.sub.10 -alkyl, C.sub.8 -C.sub.10 -cycloalkyl, C.sub.6 
-C.sub.15 -aryl, or alkylaryl, 
and 
B) at least one metal compound of the formula II 
EQU M.sup.1 (R.sup.10).sub.m (X.sup.1).sub.o II 
where 
M.sup.1 is an alkali metal or alkaline earth metal or a metal of main group 
III of the Periodic Table, 
R.sup.10 is hydrogen, C.sub.1 -C.sub.10 -alkyl, C.sub.6 -C.sub.15 -aryl, 
alkylaryl or arylalkyl, where each alkyl radical is of 1 to 10 carbon 
atoms and each aryl radical is of 6 to 20 carbon atoms, 
X.sup.1 is fluorine, chlorine, bromine or iodine, 
m is an integer from 1 to 3, 
and 
o is an integer from 0 to 2, the sum m+o corresponding to the valency of 
M.sup.1, 
to a carrier which, if required, may have been pretreated with at least one 
metal compound of the formula III 
EQU M.sup.2 (R.sup.11).sub.p (X.sup.2).sub.q III 
where 
M.sup.2 is an alkali metal or alkaline earth metal or a metal of main group 
III of the Periodic Table, 
R.sup.11 is hydrogen, C.sub.1 -C.sub.10 -alkyl, C.sub.6 -C.sub.15 -aryl, 
alkylaryl or arylalkyl, where each alkyl radical is of 1 to 10 carbon 
atoms and each aryl radical is of 6 to 20 carbon atoms, 
X.sup.2 is fluorine, chlorine, bromine or iodine, 
p is an integer from 1 to 3, 
and 
q is an integer from 0 to 2, where the sum p+q corresponds to the valency 
of M.sup.2, 
and 
b) subsequent activation by reaction with a solution or suspension of a 
compound forming metallocenium ions. 
The present invention furthermore relates to processes for the preparation 
of such supported catalyst systems, their use for the preparation of 
polyolefins and processes for the preparation of polyolefins with the aid 
of these supported catalyst systems. 
In recent years, homogeneous metallocene catalysts have made it possible to 
obtain well defined poly-1-olefins having a narrow molecular weight 
distribution and high chemical uniformity. In many cases, however, 
industrial use requires these catalysts to be converted into heterogeneous 
form, ensuring simple handling of the catalyst and effective control of 
the product morphology. Supported metallocene catalysts are known per se. 
For example, U.S. Pat. No. 5,227,440 describes systems in which SiO.sub.2 
is reacted with an alumoxane to give an alumoxane-laden carrier. 
The metallocene is applied to this carrier, an active catalyst being 
formed. 
WO 94/03506 discloses the preparation of a supported, cationic metallocene 
catalyst by application of the reaction mixture of a dialkyl metallocene 
with an ionic compound which has a Bronsted acid as the cation and a 
non-coordinating opposite ion, such as tetrakis(pentafluorophenyl)borate 
as the anion to an inorganic carrier. Here too, an active catalyst is 
obtained. 
Similarly, WO 94/07928 describes the preparation of an active, supported 
catalyst by application of a dialkyl monocyclopentadienyltitanium complex 
to an alumoxane-pretreated carrier and activation by means of 
tris(pentafluorophenyl)borane. 
Such catalysts which are already active readily give rise to problems in 
the metering of the catalyst into the reactor. 
An even more inactive catalyst which can be activated only at a later 
stage, for example during metering or in the reactor itself, is therefore 
advantageous. 
It is an object of the present invention to provide supported catalyst 
systems which do not have the stated disadvantages and in particular can 
be activated at any stage, the process used not being restricted to 
readily soluble metallocenes. It is furthermore intended to fix the 
metallocene used to a large extent on the carrier. 
We have found that this object is achieved by the supported catalyst 
systems defined at the outset. 
We have also found processes for the preparation of such supported catalyst 
systems, their use for the preparation of polyolefins and processes for 
the preparation of polyolefins with the aid of these supported catalyst 
systems. 
The novel supported catalyst systems are obtainable by applying a mixture 
of a metallocene complex of the formula I and a metal compound of the 
formula II to a carrier in a first stage a). 
Preferably used carriers are finely divided solids whose particle diameters 
are from 1 to 200 .mu.m, in particular from 30 to 70 .mu.m. Both inorganic 
and organic carriers may be used, the inorganic ones being preferred. 
Suitable carriers are, for example, silica gels, preferably those of the 
formula SiO.sub.2. a Al.sub.2 O.sub.3, where a is from 0 to 2, preferably 
from 0 to 0.5; these are therefore aluminosilicates or silica. Such 
products are commercially available, for example Silica Gel 332 from 
Grace. 
Other inorganic compounds, such as Al.sub.2 O.sub.3 or MgCl.sub.2, or 
mixtures containing these compounds may likewise be used as carriers. 
Particular examples of organic carriers are finely divided polyolefins, 
such as polypropylene and polyethylene. 
The carriers can be used directly or they may be pretreated with at least 
one metal compound of the formula III. 
Preferred metal compounds of the formula III 
EQU M.sup.2 (R.sup.11).sub.p (X.sup.2).sub.q III 
are those in which 
M.sup.2 is Li, Na, K, Mg or Al, 
R.sup.11 is C.sub.1 -C.sub.6 -alkyl, in particular C.sub.1 -C.sub.4 -alkyl, 
and 
X.sup.2 is chlorine. 
Particularly preferred metal compounds III are those in which q is zero, in 
particular magnesium alkyls and aluminum alkyls, such as (n-butyl).sub.2 
Mg and (isobutyl).sub.3 Al. If a plurality of radicals R.sup.10 or X.sup.2 
are present in a compound, they may in each case also be different. 
The metal compound of the formula III is preferably added as a solution to 
a suspension of the carrier. Particularly suitable solvents and suspending 
media are hydrocarbons, such as heptane. The amount of metal compound III 
can be varied within wide limits, from 0 to 75% by weight per g of carrier 
being particularly suitable. The temperatures, reaction times and 
pressures are not critical per se, from 0 to 80.degree. C., from 0.1 to 48 
hours and from 0.5 to 2.0 bar being preferred. 
It has proven useful to remove the excess metal compound III, after the 
pretreatment of the carrier, by washing out, for example with 
hydrocarbons, such as pentane or hexane, and to dry the carrier. 
The mixture of metallocene complex I and metal compound II is then applied 
to the carrier which may or may not have been pre-treated. 
Preferred metallocene complexes of the formula I are those in which 
M is titanium, zirconium or hafnium, 
X is chlorine, 
R.sup.1 to R.sup.4 are each hydrogen or C.sub.1 -C.sub.4 -alkyl or two 
neighboring radicals R.sup.2 and R.sup.3 together form a cyclic group of 4 
to 12 carbon atoms, 
G is silicon or carbon and 
E is &gt;NR.sup.8. 
In a metallocene complex, the radicals X may also be different, but are 
preferably identical. 
The preparation of the metallocene complex I is described, for example, in 
WO 93/08199. 
Preferred metal compounds II 
EQU M.sup.1 (R.sup.10).sub.m (X.sup.1).sub.o II 
are those in which 
M.sup.1 is Li, Mg or Al, 
R.sup.10 is C.sub.1 -C.sub.6 -alkyl, in particular C.sub.1 -C.sub.4 -alkyl, 
and 
X.sup.1 is chlorine. 
Particularly preferred metal compounds II are those in which o is zero, in 
particular magnesium alkyls and aluminum alkyls, such as (n-butyl).sub.2 
Mg and (isobutyl).sub.3 Al. If a plurality of radicals R.sup.10 and 
X.sup.1 are present in a compound, they may in each case also be 
different. 
If the carriers have been pretreated, the metal compounds II may differ 
from the metal compounds III but are preferably identical to them. 
The mixture of metallocene complex I and metal compound II is preferably 
applied to the carrier by a method in which the metallocene complex I is 
dissolved or suspended in an inert solvent, preferably in an aromatic 
hydrocarbon, such as toluene, and is reacted with the metal compound II, 
which is preferably likewise dissolved, for example in heptane, and the 
carrier is then added. 
The molar ratio of metallocene complex I to metal compound II is from 100:1 
to 10.sup.-4 :1, preferably from 1:1 to 10.sup.-2 :1. The ratio of carrier 
to metallocene complex I is preferably from 10 g:1 .mu.mol to 10.sup.-2 
g:1 .mu.mol. 
Neither the addition of the metal compound II to the metallocene complex I 
nor the addition of the carrier is critical per se, the procedure 
preferably being carried out at from 0 to 60.degree. C. over a period of 
from 0.1 to 6 hours at from 0.5 to 2.0 bar. 
After the application of the mixture of metallocene complex I and metal 
compound II to the carrier, the solvent is generally removed and the solid 
dried, said solid as such having no significant polymerization activity. 
This solid can then be activated in a further stage b) at any desired time 
by reaction with a solution or suspension of a compound forming 
metallocenium ions. 
Particularly suitable compounds forming metallocenium ions are strong, 
neutral Lewis acids, ionic compounds having Lewis acid cations and ionic 
compounds having Bronsted acids as cations. 
Preferred strong, neutral Lewis acids are compounds of the formula IV 
EQU M.sup.3 X.sup.3 X.sup.4 X.sup.5 IV 
where 
M.sup.3 is an element of main group III of the Periodic Table, in 
particular B, Al or Ga, preferably B, and 
X.sup.3, X.sup.4 and X.sup.5 are each hydrogen, C.sub.1 -C.sub.10 -alkyl, 
C.sub.6 -C.sub.15 -aryl, alkylaryl, arylalkyl, haloalkyl or haloaryl, 
where each alkyl radical is of 1 to 10 carbon atoms and each aryl radical 
is of 6 to 20 carbon atoms, or fluorine, chlorine, bromine or iodine, in 
particular haloaryl, preferably pentafluorophenyl. 
Particularly preferred compounds of the general formula IV are those in 
which X.sup.3, X.sup.4 and X.sup.5 are identical, 
tris(pentafluorophenyl)borane being preferred. 
Suitable ionic compounds having Lewis acid cations are compounds of the 
formula V 
EQU [(A.sup.a+)Q.sub.1 Q.sub.2 . . . Q.sub.z ].sup.d+ V 
where 
A is an element of main groups I to VI or of subgroups I to VIII of the 
Periodic Table, 
Q.sub.1 to Q.sub.z are each a radical having a single negative charge, such 
as C.sub.1 -C.sub.28 -alkyl, C.sub.6 -C.sub.15 -aryl, alkylaryl, 
arylalkyl, haloalkyl or haloaryl, where each aryl radical is of 6 to 20 
carbon atoms and each alkyl radical is of 1 to 28 carbon atoms, C.sub.1 
-C.sub.10 -cycloalkyl, which may be substituted by C.sub.1 -C.sub.10 
-alkyl, or halogen, C.sub.1 -C.sub.28 -alkoxy, C.sub.6 -C.sub.15 -aryloxy, 
silyl or mercapto, 
a is an integer from 1 to 6, 
z is an integer from 0 to 5 and 
d is the difference a-z, but d is greater than or equal to 1. 
Carbonium cations, oxonium cations and sulfonium cations as well as 
cationic transition metal complexes are particularly suitable. Particular 
examples are the triphenylmethyl cation, the silver cation and the 
1,1'-dimethylferrocenyl cation. 
They preferably have non-coordinating opposite ions, in particular boron 
compounds, as also mentioned in WO 91/09882, preferably 
tetrakis(pentafluorophenyl)borate. 
Ionic compounds having Bronsted acids as cations and preferably likewise 
non-coordinating opposite ions are mentioned in WO 91/09882, a preferred 
cation being N,N-dimethylanilinium. 
Since the activation can be carried out at any time, ie. before, during or 
after the metering of the supported catalyst system into the reactor, the 
activation conditions depend on this time but are not critical per se. The 
amount of compounds forming metallocenium ions is preferably from 0.1 to 
100 equivalents, based on the metallocene complex I. 
With the aid of these novel supported catalyst systems, it is possible to 
prepare polyolefins, in particular polymers of alk-1-enes. These include 
homo- and copolymers of C.sub.2 -C.sub.10 -alk-1-enes, preferably used 
monomers being ethylene, propylene, but-1-ene, pent-1-ene and hex-1-ene. 
However, cycloolefins or higher alk-l-enes and alkenes generally can also 
be used as monomers for the homo- and copolymerization. 
The preparation of the polymers can be carried out either batch-wise or, 
preferably, continuously in the conventional reactors used for the 
polymerization of alkenes. Suitable reactors include continuously operated 
loop reactors or stirred kettles, and a plurality of stirred kettles 
connected in series or high-pressure autoclaves or high-pressure tube 
reactors may also be used. 
The polymerization conditions are not critical per se, pressures of from 
0.5 to 3500, preferably from 10 to 50, bar and temperatures of from -60 to 
+200.degree. C. having proven suitable. Polymerization reactions with the 
aid of the novel catalyst systems can be carried out in the gas phase, in 
a suspension and in inert solvents. Suitable suspending media or solvents 
are hydrocarbons, preferably C.sub.4 -C.sub.10 -alkanes. 
The average molecular weight of the polymers formed can be controlled by 
the methods conventionally used in polymerization technology, for example 
by adding regulators, such as hydrogen, or by changing the reaction 
temperatures. Polymers having higher average molecular weights can be 
prepared by reducing the reaction temperatures. 
The novel supported catalyst systems are distinguished by the fact that 
they can be activated at any desired time, that the metallocene used is to 
a large extent fixed on the carrier and that the preparation process is 
not restricted to readily soluble metallocenes.

EXAMPLES 
Example 1 
Application of a mixture of dimethylsilanediyl(N-tert-butyl-amido) 
(.eta..sup.5 -2,3,4,5-tetramethylcyclopentadienyl)titanium dichloride (Ia) 
and (isobutyl).sub.3 Al to a pretreated inorganic carrier 
Example 1.1 
Pretreatment of the carrier 
20 g of SiO.sub.2 (SG332 from Grace; mean diameter: 50 .mu.m; dried for 12 
h at 100.degree. C. under reduced pressure) were suspended in 200 ml of 
dry heptane. 56 mmol of (isobutyl).sub.3 Al (as a 2-molar solution in 
heptane) were added dropwise in the course of 30 minutes at room 
temperature, the temperature increasing to 45-50.degree. C. Stirring was 
then continued over night, and the solid was filtered off and washed twice 
with 30 ml of hexane and twice with 30 ml of pentane. Finally, drying was 
carried out under reduced pressure from an oil pump until the weight 
remained constant. 
Example 1.2 
Application of the mixture of metallocene I and metal compound II 
141 .mu.mol (50 mg) of Ia 
##STR2## 
were suspended in 50 ml of absolute toluene. After the addition of 5 mmol 
of (isobutyl).sub.3 Al (2-molar solution in heptane), the solution 
obtained was stirred for 10 minutes. Thereafter, 5 g of the carrier 
prepared under 1.1 were slowly added and the suspension obtained was 
stirred for a further 60 minutes. The solvent was then stripped off under 
reduced pressure and the solid residue was dried under reduced pressure 
from an oil pump until a free-flowing powder remained. 
Example 2 
Preparation of polyethylene (PE) in suspension with 
tris(pentafluorophenyl)borane as the compound forming metallocenium ions 
350 mg of the supported catalyst prepared in Example 1 were suspended in 
1000 ml of absolute toluene to which 2 mmol of (isobutyl).sub.3 Al (as a 
2-molar solution in heptane) had been added. The suspension was heated to 
70.degree. C. while passing in ethene (1 bar), and 12.5 mg (0.025 mmol) of 
tris(pentafluorophenyl)borane, dissolved in 5 ml of absolute toluene, were 
slowly added. After the addition of only 1 ml, substantial ethene uptake 
was observed. The polymerization was terminated after 60 minutes because 
the batch was no longer stirrable. Working up gave 10 g of PE with 
[.eta.]=6.5 dl/g (measured according to DIN 53 728, Part 4). 
Comparative Examples 1 and 2 
Comparative Example 1 
3.7 mg (10.4 .mu.mol) of Ia were dissolved in 1000 ml of absolute toluene. 
After the addition of 4 mmol of (isobutyl).sub.3 Al (as a 2-molar solution 
in heptane), the solution was heated to 70.degree. C. while passing in 
ethene (1 bar). A solution of 25 mg (49 .mu.mol) of 
tris(pentafluorophenyl)borane, dissolved in 10 ml of absolute toluene, was 
then slowly added via a dropping funnel. After the addition of only 4 ml 
of this solution, substantial ethene uptake was observed, finally reaching 
about 6 l/h. After a polymerization time of 60 minutes, the batch was no 
longer stirrable and the experiment was terminated. Working up gave 10 g 
of PE with [.eta.]=4.1 dl/g (measured according to DIN 53 728, Part 4). 
Comparative Example 2 
Comparative Example 1 was repeated, only 2 mmol of (isobutyl).sub.3 Al 
being used instead of 4 mmol. No detectable reaction occurred here.