Activator system for metallocene compounds

Details Activator system for metallocene compounds Activator system for metallocene compounds

1999-09-23

2002-04-30

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...

C526S160000, C526S943000, C502S104000, C502S117000, C502S152000

Reexamination Certificate

active

06380332

ABSTRACT:

The present invention relates to a process for the preparation of a supported olefin polymerization catalyst composition, comprising a support, a metallocene, and an aluminoxane. The invention also relates to a supported olefin polymerization catalyst composition which has been prepared according to said process and to the use of such a supported olefin polymerization catalyst composition for the polymerization of at least one olefin.
In many olefin polymerization processes using a single site catalyst, it is desirable to support the catalyst on a carrier or support. Usually such supported catalyst compositions include a metallocene and an aluminoxane supported on an inorganic oxide carrier such as silica and/or alumina.
For example, WO 96/00243 describes a method for producing a supported catalyst composition by mixing a bridged bis-indenyl metallocene and an aluminoxane in a solvent to form a solution, and then combining the solution and a porous support, whereby the total volume of the solution is less than that at which a slurry is formed. A typical support used was previously heated silica MS 948 (Grace) and a typical aluminoxane used was gel-free methyl aluminoxane (MAO), both of which were used in all of the examples.
According to S. Srinvasa Reddy, Polymer Bulletin, 36 (1996) 317-323, the ethylene polymerization activity of tetraisobutyldialuminoxane cocatalyst was clearly lower than the activity of methylaluminoxane cocatalyst. This reflects the previous general opinion, that only methyl aluminoxane as a cocatalyst gave satisfactory ethylene polymerization catalyst activities.
The purpose of the present invention is to replace MAO as an olefin polymerization procatalyst. More specifically, the present invention aims at providing an olefin polymerization catalyst composition including a higher C
2
-C
10
alkyl aluminoxane, which has commercially satisfactory activity when producing olefin homopolymers and copolymers. A further goal of the present invention is a supported olefin polymerization catalyst composition for use in gas phase, slurry phase or liquid/solution phase polymerizations.
The above mentioned purposes of the invention have now been realized by a novel process for the preparation of a supported olefin polymerization catalyst composition, comprising a support, a metallocene, and an aluminoxane. The claimed process is mainly characterized by contacting a support comprising a solid compound which is one of an aluminium oxide, a mixed aluminium oxide such as silica-alumina, an aluminium salt, a magnesium halide or a C
1
-C
8
alkoxy magnesium halide, in any order with at least
a) an organometallic compound of the general formula (1):
R
1
MX
v−1
  (1)
wherein each R is the same or different and is a C
1
-C
10
alkyl group; M is a metal of Group 1, 2, 12 or 13 of the Periodic Table (IUPAC 1990); each X is the same or different and one of a halogen atom, a hydrogen atom, a hydroxyl radical or a C
1
-C
8
hydrocarbyloxy group; 1 is 1, 2 or 3; v is the oxidation number of the metal M,
b) a metallocene of the general formula (2):
(CpY)
m
M′X′
n
Z
o
  (2)
wherein each CpY is the same or different and is one of a mono- or polysubstituted, fused or non-fused, homo- or heterocyclic cyclopentadienyl, indenyl, tetrahydroindenyl, fluorenyl, or octahydrofluorenyl ligand, the ligand being covalently substituted at its cyclopentadienyl ring with at least one substituent Y which is one of a —OR′, —SR′, —NR′
2
, —C(H or R′)═, or —PR′
2
radical, each R′ being the same or different and being one of a C
1
-C
16
hydrocarbyl group, a tri-C
1
-C
8
hydrocarbyl silyl group or a tri-C
1
-C
8
hydrocarbyloxy silyl group; M′ is a transition metal of Group 4 of the Periodic Table and bound to the ligand CpY at least in an &eegr;
5
bonding mode; each X′ is the same or different and is one of a hydrogen atom, a halogen atom, a C
1
-Ck
8
hydrocarbyl group, a C
1
-C
8
hydrocarbylheteroatom group or a tri-C
1
-C
8
hydrocarbylsilyl group or two X′ form a ring with each other; Z is a bridge atom or group between two CpY ligands or one CpY ligand and the transition metal M′; m is 1 or 2; o is 0 or 1; and n is 4−m if there is no bridge Z or Z is a bridge between two CpY ligands or n is 4−m−o if Z is a bridge between one CpY ligand and the transition metal M′, and
c) an aluminoxane of the following general formulas (3):
 (OAlR″)
p
  (3 general)
wherein each R″ and each R′″ is the same or different and is a C
2
-C
10
alkyl group; and p is an integer between 1 and 40,
and recovering said supported olefin polymerization catalyst composition.
By mono- or polysubstituted is meant that, in addition to said substituent Y, there may optionally be other substituents at the rings at said ligands CpY.
By fused or non-fused is meant that any ring at said ligands may be fused or non-fused, i.e. have at least two atoms in common, with at least one further ring.
By homo- and heterocyclic is meant that any ring of said ligands may have only carbon ring atoms (homo- or isocyclic) or may have other ring atoms than carbon (heterocyclic).
It has thus been realized that a C
2
-C
10
alkyl aluminoxane (i.e. a non-methyl aluminoxane) can successfully be used as the cocatalyst, if a support comprising an aluminium pure oxide, mixed oxide or salt, or a magnesium halide, is first treated with a metal alkyl compound and then activated with a metallocene having a —OR′, —SR′, —NR′
2
, —C(H or R′)═, or —PR′
2
substituent at the cyclopentadienyl ring.
According to non-limiting model, said electron pair of double bond substituents at the cyclopentadienyl ring delocalize it's negative charge and help to ionise the metallocene, whereby the transition metal M becomes more cationic (electron density deficient). By combining this with special metyl alkyl treatment of acidic surfaces (like alumina, aluminium phosphate, silica-alumina, etc.) the cationisation can be enhanced. This improves the catalytic interaction between the metallocene and the aluminoxane and enables the use of higher aluminoxanes like those of the above formula (3).
Generally, said support can be contacted with compounds a), b) and c) in any order. Thus, the support can e.g. be impregnated with a solution of the three compounds a), b) and c), first with compound a) and then with a solution containing compound b) and compound c), or preferably, contacting said support at first with
a) said organometallic compound of the general formula (1), then with
b) said metallocene of the general formula (2), and after that with
c) said aluminoxane of the general formulas (3).
According to one embodiment of the invention, the contacting of the support with compounds a), b) and c) takes place by contacting the support with one or several solutions of the compounds. The support can, for example, be contacted with a solution of said organometallic compound (1) and thereafter with a solution containing said metallocene (2) and said aluminoxane (3). In a preferable embodiment of the invention, the contacting takes place by
a
1
) contacting said support with a solution of said organometallic compound (1), and removing the supernatant from the contacting product,
b
1
) contacting the product of step a
1
) with a solution of said metallocene (2), and removing the supernatant from the contacting product, and
c
1
) contacting the product of step b
1
) with a solution of said aluminoxane (3), and removing the supernatant from the contacting product.
When contacting said support with compounds a), b) and c) in liquid form such as the form of a solution, a slurry or a non-slurry contacting product can be formed. However, it is preferable to impregnate the support with a liquid, the volume of which is less than at which a slurry is formed. This means that the volume of said liquid is less than or approximately equal to the volume of the support pores.
The support used in the pro

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