Catalyst composition

Details Catalyst composition Catalyst composition

2001-06-04

2002-05-07

Nutter, Nathan M. (Department: 1711)

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

Mixing of two or more solid polymers; mixing of solid...

C525S240000

Reexamination Certificate

active

06384144

ABSTRACT:

The present invention relates to a catalyst composition comprising a polymerization catalyst based on an early transition metal component and a polymerization catalyst based on a late transition metal component.
The use of catalysts of the Ziegler type or the metallocene type for the polymerization of nonpolar olefins such as ethylene and propylene is known. Such catalysts usually comprise an early transition metal component, for example a halide-containing titanium or zirconium compound, in combination with an excess of a cocatalyst, for example an aluminum compound. Recently, the activation of suitable transition metal compounds using stoichiometric amounts of a cocatalyst such as a [Ph
3
C]
+
or [Me
2
NPh]
+
salt of a non-coordinated anion has been described.
The use of catalyst compositions comprising two or more different olefin polymerization catalysts of the Ziegler type or the metallocene type is known. For example, a combination of two catalysts of which one produces a polyethylene having a different mean molar mass than the other can be used for producing reactor blends having broad molecular weight distributions (WO 95/11264). The polymer blends obtained can have improved processing and use properties.
The addition of metal components, including later transition metals, to olefin polymerization catalysts based on early transition metals for increasing the activity or stability of the latter catalysts has been described many times (Herrmann, C.; Streck, R.; Angew. Makromol. Chem. 94 (1981) 91-104).
The synthesis of branched polymers from ethylene without use of a comonomer by means of bimetallic catalysts in which one catalyst oligomerizes part of the ethylene and the other copolymerizes the resulting oligomers with ethylene has been described (Beach, David L.; Kissin, Yury V.; J. Polym. Sci., Polym. Chem. Ed. (1984), 22, 3027-42. Ostoja-Starzewski, K. A.; Witte, J.; Reichert, K. H., Vasiliou, G. in Transition Metals and Organometallics as Catalysts for Olefin Polymerization. Kaminsky, W.; Sinn, H. (editors); Springer-Verlag; Heidelberg; 1988; S. 349-360). The last literature reference describes, for example, the use of a nickel-containing oligomerization catalyst in combination with a chromium-containing polymerization catalyst.
It is an object of the present invention to provide a catalyst composition which is suitable for preparing polyolefin blends comprising at least two different polyolefins.
We have found that this object is achieved by means of a specific catalyst composition.
The present invention accordingly provides a catalyst composition comprising at least two different polymerization catalysts of which a) at least one is a polymerization catalyst based on an early transition metal component and b) at least one is a polymerization catalyst based on a late transition metal component.
The invention further provides a process for the polymerization of olefins in the presence of the catalyst composition of the present invention. A preferred embodiment of the process of the present invention is a process for the homopolymerization of ethylene by means of the catalyst composition of the present invention, where particular preference is given to obtaining a blend of polyethylenes having different branching structures.
For the purposes of the present invention, an “early transition metal” is a metal of groups IIIa to VIIa of the Periodic Table of the Elements or a metal of the lanthanide group, and a “late transition metal” is a metal of groups VIIIa and IB of the Periodic Table of the Elements. The expressions “oligomerization” and “oligomer” refer to products or product mixtures which, based on the number average (M
n
), consist of less than 400 monomer units. The expressions “polymerization” and “polymer” or “polyolefin” refer to products or product mixtures which, based on the number average (M
n
), consist of more than 400, preferably more than 1000, monomer units. The term “polymerization catalyst” refers to catalysts which are suitable for preparing polymers or polyols, ie. for preparing products or product mixtures which, based on the number average, consist of more than 400 monomer units, preferably more than 1000 monomer units. The catalyst composition of the present invention comprises a) at least one polymerization catalyst based on an early transition metal component and b) at least one polymeerization catalyst based on a late transition metal component, of which each leads to the formation of a different polymer or polyolefin. Each transition metal component comprises exactly one transition metal.
As catalyst component based on an early transition metal, the catalyst composition of the present invention preferably comprises Ziegler catalyst components (as described, for example, in Falbe, J.; Regitz, M. (editors); Römpp Chemie Lexikon; 9th edition; Thieme; 1992; New York; volume 6, pp. 5128-5129) and/or metallocene catalyst components. Particular preference is given to metallocene catalyst components.
The Ziegler catalyst component is preferably a compound of a metal of group IVa (ie. titanium, zirconium or hafnium), Va (eg. vanadium or niobium) or VIa (eg. chromium or molybdenum) of the Periodic Table of the Elements. Preference is given to halides, oxides, oxyhalides, hydroxides or alkoxides. Examples of Ziegler catalyst components are, without constituting a limitation: titanium tetrachloride, zirconium tetrachloride, hafnium tetrachloride, titanium trichloride, vanadium trichloride, vanadium oxychloride, chromium trichloride or chromium oxide.
For the purposes of the present invention, metallocene catalyst components are, for example, cyclopentadienyl complexes. Preference is given to cyclopentadienyl complexes of metals of group IIIa and the lanthanide group (eg. lanthanum or yttrium), and also metals of group IVa (ie. titanium, zirconium or hafnium), Va (eg. vanadium or niobium) or VIa (eg. chromium or molybdenum) of the Periodic Table of the Elements; particular preference is given to cyclopentadienyl complexes of titanium, zirconium or hafnium. The cyclopentadienyl complexes can be, for example, bridged or unbridged biscyclopentadienyl complexes as are described, for example, in EP 129 368, EP 561 479, EP 545 304 and EP 576 970, monocyclopentadienyl complexes such as bridged amidocyclopentadienyl complexes as are described, for example, in EP 416 815, multinuclear cyclopentadienyl complexes as described in EP 632 063, tetrahydropentalenes substituted by pi ligands as described in EP 659 758 or tetrahydroindenes substituted by pi ligands as described in EP 661 300.
Preferred metallocene catalyst components are unbridged or bridged metallocene compounds of the formula I,
where
M
1
is a metal of group IIIa, IVa, Va or VIa of the Periodic Table of the Elements, in particular Ti, Zr or Hf,
R
1
are identical or different and are hydrogen or SiR
3
3
, where R
3
are identical or different and are each hydrogen or a C
1
-C
40
-group such as C
1
-C
20
-alkyl, C
1
-C
10
-fluoroalkyl, C
1
-C
10
-alkoxy, C
6
-C
20-aryl, C
6
-C
10
-fluoroaryl, C
6
-C
10
-aryloxy, C
2
-C
10
-alkenyl, C
7
-C
40
-arylalkyl, C
7
-C
40
-alkylaryl or C
8
-C
40
-arylalkenyl, or R
1
is a C
1
-C
30
-group such as C
1
-C
25
-alkyl, eg. methyl, ethyl, tert-butyl, cyclohexyl or octyl, C
2
-C
25
-alkenyl, C
3
-C
15
-alkylalkenyl, C
6
-C
24
-aryl C
5
-C
24
-heteroaryl such as pyridyl, furyl or quinolyl, C
7
-C
30
-arylalkyl, C
7
-C
30
-alkylaryl, fluorine-containing C
1
-C
25
-alkyl, fluorine-containing C
6
-C
24
-aryl, fluorine-containing C
7
-C
30
-arylalkyl, fluorine-containing C
7
-C
30
-alkylaryl or C
1
-C
12
-alkoxy, or two or more radicals R
1
can be joined to one another in such a way that the radicals R
1
and the atoms of the cyclopentadienyl ring which connect them form a C
4
-C
24
ring system which may in turn be substituted,
is 5 when v=0, and 1 is 4 when v=1,
Y is either
a) an element of main group V (eg. nitrogen or phosphorus) or VI (eg. oxygen or sulfur) of the Periodic Table of the Elements which bears one or two

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