Catalysts based on fulvene metal complexes

Details Catalysts based on fulvene metal complexes Catalysts based on fulvene metal complexes

2001-06-08

2002-05-28

Wu, David W. (Department: 1713)

Catalyst, solid sorbent, or support therefor: product or process

Catalyst or precursor therefor

Organic compound containing

C502S103000, C502S154000, C526S160000, C526S348000

Reexamination Certificate

active

06395672

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to a catalyst system based on fulvene metal complexes as well as their use for the polymerisation of unsaturated compounds, in particular for the polymerisation and copolymerisation of olefins and/or dienes.
SUMMARY OF THE INVENTION
The use of cyclopentadienyl metal complexes, in particular the use of metallocene complexes in a mixture with activating co-catalysts, preferably alumoxanes (MAO), for the polymerisation of olefins and diolefins has been known for a long time (e.g. EP-A 129 368, 347 128, 347 129, 69 951, 351 392, 485 821, 485 823).
The metallocenes have proved to be highly effective, specific catalysts in the polymerisation, of in particular olefins. In order, therefore, to increase the activity, selectivity, control of the micro-structure, the molecular weights and the molecular weight distribution, a large number of novel metallocene catalysts or metallocene catalyst systems have been developed in recent years for the polymerisation of olefinic compounds.
The MAO-based catalyst systems described above have serious drawbacks, however, as will be explained in detail below. Firstly, aluminoxanes, in particular MAO, can be manufactured with high reproducibility neither in situ nor during preforming. MAO is a mixture of various aluminium alkyl-containing species, which are present in equilibrium with each other. The number and the structure of the aluminium compounds occurring in MAO is not defined precisely. The polymerisation of olefins with catalyst systems that contain MAO is therefore not always reproducible. Moreover, MAO is not storable over long periods and its composition changes under thermal stress. A major disadvantage is the high surplus of MAO which is required for the activation of metallocenes. The large MAO/metallocene ratio is an essential pre-requisite for obtaining high catalyst activities. This results in a critical process drawback, as the aluminium compound has to be separated from the polymer during the working up. MAO is furthermore a cost-determining factor. High MAO surpluses are uneconomic for industrial application.
In order to circumvent these drawbacks, alumoxane-free polymerisation catalysts have been developed in recent years. For example, Jordan et al report in J. Am. Chem. Soc., Vol. 108 (1986), 7410 on a cationic zirconocene-methyl complex which possesses tetraphenyl borate as counter-ion and polymerises ethylene into methylene chloride. In EP-A 277 003 and EP-A 277 004 ionic metallocenes are described which are produced by the reaction of metallocenes with ionising reagents. In EP-A 468 537 catalysts of ionic structure are described which are obtained by reacting metallocene-dialkyl compounds with tetrakis(pentafluorophenyl)boron compounds. The ionic metallocenes are suitable as catalysts for the polymerisation of olefins. A disadvantage is however the great sensitivity of the catalysts to impurities such as e.g. humidity and oxygen. Measures therefore have to taken during the performance of polymerisations to guarantee as great a purity of the monomers and solvents used as possible. This is very complicated technically and expensive.
In order to overcome these drawbacks, there are described in EP-A 427 697 and in WO 92/101723 processes for the polymerisation of olefins in which a combination of metallocene dichlorides with aluminium alkyls and tetrakis(pentafluorophenyl)boron compounds is used as a catalyst system. The aluminium alkyl compounds on the one hand serve as alkylation agents of the metallocene component and on the other function as scavengers in order to protect the active catalyst species against impurities.
The methods corresponding to the prior art for preparing the cationic metallocenes have the drawback, however, that the cationising reagents, e.g. tetrakis(pentafluorophenyl)boron compounds, are difficult to synthesise in some cases and their use is cost-intensive.
According to Bercaw et al., JACS (1972), 94, 1219, there is obtained by thermolysis of bis(&eegr;
5
-pentamethylcyclopentadienyl)titanium dimethyl the fulvene complex (&eegr;
6
-2,3,4,5-tetramethylcyclopentadienyl-1-methylene)(&eegr;
5
-pentamethylcyclopenta-dienyl)-titanium methyl. Nothing is known about the polymerisation activity of this complex. In T. J. Marks et al., JACS (1988), 110, 7701 the thermolysis of pentamethyl-cyclopentadienyl complexes of zirconium and hafnium is described. By thermolysis of bis(&eegr;
5
-pentamethyl-cyclopentadienyl)zirconium diphenyl the fulvene complex (&eegr;
6
-2,3,4,5-tetra-methylcyclopentadienyl-1-methylene)(&eegr;
5
-pentamethylcyclopentadienyl)-zirconium phenyl is obtained. This compound is not polymerisation-active on its own.
SUMMARY OF THE INVENTION
The object therefore existed of finding a catalyst system which prevents the above-mentioned drawbacks. In addition, processes based on aluminoxane-free metallocene systems were to be developed.
It has now been found, surprisingly, that catalyst systems based on fulvene metal complexes are particularly highly suitable for the objects set.
The present invention therefore provides a catalyst system consisting of
a) a fulvene metal complex with the formula
 in which
M is a metal from the group IIIb, IVb, Vb, VIb or of the lanthanides or of the actinides of the Periodic Table of the Elements [N. N. Greenwood, A. Earnshaw, Chemie der Elemente, VCH 1990],
A signifies an optionally uni- or multi-bridged anionic ligand,
R
1
, R
2
, R
3
, R
4
, R
5
, R
6
, R
7
are identical or different and stand for hydrogen, halogen, a cyano group, a C
1
to C
20
alkyl group, a C
1
to C
10
fluoroalkyl group, a C
6
to C
10
fluoroaryl group, a C
1
to C
10
alkoxy group, a C
6
to C
20
aryl group, a C
6
to C
10
aryloxy group, a C
2
to C
10
alkenyl group, a C
7
to C
40
arylalkyl group, a C
7
to C
40
alkylaryl group, a C
8
to C
40
arylalkenyl group, a C
2
to C
10
alkinyl group, a silyl group optionally substituted by C
1
to C
10
hydrocarbon groups or
R
1
, R
2
, R
3
, R
4
, R
5
, R
6
, R
7
form respectively together with the atoms linking them one or more aliphatic or aromatic ring systems, which can contain one or more hetero atoms (O,N,S) and have 5 to 10 carbon atoms,
m signifies 0, 1, 2 or 3 and
k is 1, 2 or 3 and the sum of m+k comes to 1 to 5 as a function of the oxidation state of M and
b) an aluminoxane- and boron-free Lewis acid suitable for activating the metal complex a), wherein the molar ratio of component a) to component b) lies in the range of 1:0.1 to 1:10000, preferably 1:1 to 1:1000.
The synthesis of the fulvene metal complexes of formula (I) is known and described for example in T. J. Marks et al., Organometallics 1987, 6, 232-241.
DETAILED DESCRIPTION OF THE INVENTION
The present invention further provides a process for producing a catalyst system, characterised in that a mixture of an aluminoxane- and boron-free Lewis acid suitable for activation and a metal complex of formula (II)
in which
M, A, R
1
to R
7
have the signification indicated according to claim 1, and
X stands for hydrogen, halogen, a C
1
to C
30
alkyl group, a C
6
to C
10
aryl group, a C
2
to C
10
alkenyl group, a C
7
to C
40
arylalkyl group, a C
7
to C
40
alkylaryl group, a C
8
to C
40
arylalkenyl group, a C
2
to C
10
alkinyl group, an optionally substituted silyl group,
is treated thermally in a suitable reaction medium.
The thermal treatment takes place in the temperature range from 60° C. to 250° C., preferably from 90° C. to 150° C. The duration of the thermal treatment lies in the range from 1 minute to 20 hours, preferably in the range from 15 minutes to 120 minutes. Suitable reaction media are for example aromatic hydrocarbons, such as benzene or toluene, or aliphatic hydrocarbons, such as hexane, heptane, octane, cyclohexane or mixtures of the various hydrocarbons. The thermal treatment is not carried out in the presence of an olefin or diolefin. The molar ratio of the Lewis acid to the metal complex of formula (II) lies in the range from 1:0.1 to 1:10000, preferably 1:1 to 1:1000.
The

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