Method for producing a supported catalyst system

Details Method for producing a supported catalyst system Method for producing a supported catalyst system

2000-12-18

2002-08-13

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...

C526S129000, C526S133000, C526S142000, C526S160000, C526S351000, C526S352000, C526S348000, C526S943000, C502S120000, C502S123000, C502S126000, C502S132000, C502S152000, C502S154000

Reexamination Certificate

active

06433111

ABSTRACT:

The present invention relates to a process for preparing a supported catalyst, which comprises the following steps:
A) reacting an inorganic support material with a metal compound of the formula I
M
1
(R
1
)
r
(R
2
)
s
(R
3
)
t
(R
4
)
u
  I
 where
M
1
is an alkali metal, an alkaline earth metal or a metal of main group III or IV of the Periodic Table,
R
1
is hydrogen, C
1
-C
10
-alkyl, C
6
-C
15
-aryl, alkylaryl or arylalkyl each having from 1 to 10 carbon atoms in the alkyl radical and from 6 to 20 carbon atoms in the aryl radical,
R
2
to R
4
are hydrogen, halogen, C
1
-C
10
-alkyl, C
6
-C
15
-aryl, alkylaryl, arylalkyl, alkoxy or dialkylamino each having from 1 to 10 carbon atoms in the alkyl radical and from 6 to 20 carbon atoms in the aryl radical,
r is an integer from 1 to 4 and
s,t and u are integers from 0 to 3, where the sum r+s+t+u corresponds to the valence of M
1
,
B) reacting the material obtained as described in A) with a metallocene complex and a compound capable of forming metallocenium ions and
C) subsequently reacting the resulting material with a metal compound of the formula II
M
2
(R
5
)
o
(R
6
)
p
(R
7
)
q
  II
 where
M
2
is an alkali metal, an alkaline earth metal or a metal of main group III of the Periodic Table,
R
5
is hydrogen, C
1
-C
10
-alkyl, C
6
-C
15
-aryl, alkylaryl or arylalkyl each having from 1 to 10 carbon atoms in the alkyl radical and from 6 to 20 carbon atoms in the aryl radical,
R
6
and R
7
are hydrogen, halogen, C
1
-C
10
-alkyl, C
6
-C
15
-aryl, alkylaryl, arylalkyl or alkoxy each having from 1 to 10 carbon atoms in the alkyl radical and from 6 to 20 carbon atoms in the aryl radical,
o is an integer from 1 to 3 and
p and q are integers from 0 to 2, where the sum o+p+q corresponds to the valence of M
2
.
The invention further relates to a supported catalyst system which is obtainable by the process of the present invention and also to the use of this catalyst system for the homopolymerization of ethylene or propylene or the copolymerization of ethylene or propylene with C
3
-C
10
-&agr;-olefins and for the gas-phase polymerization of olefins.
Particularly for the gas-phase polymerization and the suspension polymerization of ethylene and higher &agr;-olefins, preference is given to using supported catalyst systems. Supported metallocene catalysts in particular give polymer products having extraordinary material properties.
Many metallocene complexes require activation to develop their full catalytic activity. As activator compounds, use is usually made of aluminoxanes (see, for example, EP-B1-035 242) or compounds which convert the metallocene into a metallocenium cation and stabilize this coordinatively unsaturated cationic structure by means of a suitable noncoordinating counterion (see, for example, EP-A-277 004).
The productivity of these catalyst systems and thus their economical usability depends significantly on the type of support material and, in particular, on the method of application to the support. A very efficient method of applying, in particular, cationically activatable metallocene catalyst systems to a support is described in DE-A 19 606 167.
To increase the productivity of cationically activated metallocene catalysts, weakly coordinating Lewis bases are added to such catalyst systems (cf. EP-B1-0648 786 and EP-A1-0 771 822). However, these catalyst systems are mostly homogeneous, unsupported catalyst systems. The Lewis base is always used in an at least 10-fold molar excess relative to the metallocene complex, as a rule in a 50- to 250-fold excess. Although EP-A-0 771 822 states that the metallocene complex can also be applied to a support, the Lewis base is always added to the polymerization mixture in a soluble form and in a considerable excess.
Since relatively high concentrations of the Lewis bases added have an inhibiting effect on the metallocene catalysts and, in addition, represent an undesirable extractable component in the polymer, it would be desirable to reduce the Lewis base concentration while retaining the positive effect of these compounds on the catalyst productivity.
It is an object of the present invention to find a process for preparing a supported metallocene catalyst system which no longer has the disadvantages of the prior art and displays a high productivity when small amounts of Lewis bases are added.
We have found that this object is achieved by the process described at the outset for preparing a supported catalyst when the supported catalyst obtained in this way or its precursor is brought into contact with a Lewis base in an amount of from 0.1 to <10 mole per mole of metallocene complex.
Furthermore, we have found a supported catalyst system which is obtainable by this process and also the use of this supported catalyst system in the homopolymerization and copolymerization of olefins.
The supported catalyst systems of the present invention are obtainable by, in a first step A), reacting an inorganic support material with a metal compound of the formula I.
Support materials used are preferably finely divided solids whose particle diameters are in the range from 1 to 200 &mgr;m, in particular from 30 to 70 &mgr;m.
Suitable support materials are, for example, silica gels, preferably those of the formula SiO
2
.a Al
2
O
3
, where a is a number from 0 to 2, preferably from 0 to 0.5; these are thus aluminosilicates or silicon dioxide. Such products are commercially available, e.g. silica gel 332 from Grace. These support materials can be subjected to a thermal treatment to remove the adsorbed water or can be calcined; preference is given to carrying out a treatment at 80-200° C., preferably 100-150° C.
Other inorganic compounds such as Al
2
O
3
or MgCl
2
or mixtures comprising these compounds can likewise be used as support materials.
Among the metal compounds of the formula I, preference is given to those in which M
1
is a metal of main group III of the Periodic Table, in particular aluminum, R
1
is C
1
-C
10
-alkyl and R
2
to R
4
are C
1
-C
10
-alkyl. In the particularly preferred case of M
1
being aluminum, u is zero and the radicals R
1
to R
3
are, in particular, identical, preferably methyl, ethyl, isobutyl or hexyl, preferably isobutyl.
The metal compound of the formula I is preferably added as solution to a suspension of the support. Suitable solvents or suspension media are, in particular, hydrocarbons such as heptane. The amount of metal compound I can vary within wide limits and the minimum amount depends on the number of hydroxy groups in the support. The temperatures, reaction times and pressures are not critical per se; preference is given to temperatures of from 0 to 80° C. and reaction times of from 0.1 to 48 hours.
It has been found to be useful to remove the excess metal compound I by washing after the pretreatment of the support, for example using hydrocarbons such as pentane or hexane, and to dry the support.
The material prepared in this way can be stored for up to 6 months and is not pyrophoric.
This material is then, in a further step B), reacted with a metallocene complex and a compound capable of forming metallocene ions.
Suitable metallocene complexes are, for example, compounds of the formula III:
where the substituents have the following meanings:
M is titanium, zirconium, hafnium, vanadium, niobium or tantalum,
X is fluorine, chlorine, bromine, iodine, hydrogen or C
1
-C
10
-alkyl, preferably chlorine,
R
8
to R
12
are hydrogen, C
1
-C
10
-alkyl, 5- to 7-membered cycloalkyl which may in turn bear a C
1
-C
10
-alkyl group as substituent, C
6
-C
15
-aryl or arylalkyl, where two adjacent radicals may also together be a cyclic group having from 4 to 15 carbon atoms, or Si(R
13
)
3
where
R
13
is C
1
-C
10
-alkyl, C
3
-C
10
-cycloalkyl or C
6
-C
15
-aryl,
where the radicals
R
14
to R
18
are hydrogen, C
1
-C
10
-alkyl, 5- to 7-membered cycloalkyl which may in turn bear a C
1
-C
10
-alkyl group as substituent, C
6
-C
15
-aryl or arylalkyl, where two adjacent radicals may also together be a cyclic

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