Process for the preparation of a polyolefin

Details Process for the preparation of a polyolefin Process for the preparation of a polyolefin

1995-04-07

2002-07-02

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...

C526S943000, C526S352000, C526S351000, C526S348600, C526S348400, C526S348200, C502S403000

Reexamination Certificate

active

06414096

ABSTRACT:

The invention relates to an olefin polymer of high molecular weight and low residual catalyst content.
Isotactic PP is prepared with the aid of ethylene-bis-(4,5,6,7)-tetrahydro-1-indenyl)-zirconium dichloride together with an aluminoxane in a suspension polymerization reaction (cf. EP-A-185,918). The polymer has a narrow molecular weight distribution (M
w
/M
n
1.6 to 2.6).
It has been possible to achieve a considerable increase in the activity of the catalyst system by a specific preactivation method (cf. DE-3,726,067). The particle morphology of the polymer has likewise been improved by this preactivation method.
The molecular weights of the polymers obtained in accordance with these two applications are still too low for industrial use.
There was thus the object of discovering a process for the preparation of a high molecular weight olefin polymer which can be carried out in an industrially interesting temperature range with a high catalyst activity.
It has been found that the object can be achieved by polymerization of olefins in the presence of certain metallocene catalysts.
The invention thus relates to a process for the preparation of a polyolefin by polymerization of an olefin of the formula R
11
—CH═CH—R
12
, in which R
11
and R
12
are identical or different and are a hydrogen atom or a C
1
-C
14
-alkyl radical, or R
11
and R
12
, together with the carbon atom joining them, form a ring having 4 to 28 carbon atoms, at a temperature of 0° C. to 150° C., under a pressure of 0.5 to 100 bar, in solution, in suspension or in the gas phase and in the presence of a catalyst which consists of a metallocene and an aluminoxane of the formula (II)
for the linear type, and/or of the formula (III)
for the cyclic type, in which, in the formulae (II) and (III), R
10
is a C
1
-C
6
-alkyl group and n is an integer from 2 to 50, wherein the metallocene is at least one compound of the formula (I)
in which
M is zirconium or hafnium,
R
1
and R
2
are identical or different and are a hydrogen atom, a C
1
-C
10
-alkyl group, a C
1
-C
10
-alkoxy group, a C
6
-C
10
-aryl group, a C
6
-C
10
-aryloxy group, a C
2
-C
10
-alkenyl group, a C
7
-C
40
-arylalkyl group, a C
7
-C
40
-alkylaryl group, a C
8
-C
40
-arylalkenyl group or a halogen atom,
R
3
and R
4
are identical or different and are a hydrogen atom, a halogen atom, a C
1
-C
10
-alkyl group or a —NR
2
9
, —SR
9
, —OR
9
, —OSiR
3
9
, —SiR
3
9
or —PR
2
9
radical, in which R
9
is a C
1
-C
10
-alkyl group, a C
6
-C
10
-aryl group or, in the case of radicals containing Si or P, also a halogen atom,
or in each case two adjacent radicals R
3
or R
4
, together with the carbon atoms joining them, form a ring and
R
5
, R
6
, R
7
and R
8
are identical or different and are a hydrogen atom, a halogen atom, a C
1
-C
30
-alkyl group, a C
1
-C
10
-fluoroalkyl group, a C
6
-C
10
-aryl group, a C
6
-C
10
-fluoroaryl group, a C
1
-C
10
-alkoxy group, a C
2
-C
10
-alkenyl group, a C
7
-C
40
-arylalkyl group, a C
8
-C
40
-arylalkenyl group, a —SiMe
3
group, an —OSiMe
3
group or a C
7
-C
40
-alkylaryl group, or R
5
and R
6
or R
7
and R
9
, in each case together with the atoms joining them, form a ring.
The catalyst to be used for the process according to the invention consists of an aluminoxane and at least one metallocene of the formula I
in which
M is hafnium or zirconium, preferably zirconium,
R
1
and R
2
are identical or different and are a hydrogen atom, a C
1
-C
10
-, preferably C
1
-C
3
-alkyl group, a C
1
-C
10
-, preferably C
1
-C
3
-alkoxy group, a C
6
-C
10
-, preferably C
6
-C
8
-aryl group, a C
6
-C
1
l-, preferably C
6
-C
8
-aryloxy group, a C
2
-C
10
-, preferably C
2
-C
4
-alkenyl group, a C
7
-C
40
-, preferably C
7
-C
10
-arylalkyl group, a C
7
-C
40
-, preferably C
7
-C
12
-alkylaryl group, a C
8
-C
40
-, preferably C
8
-C
12
-arylalkenyl group or a halogen atom, preferably chlorine.
R
3
and R
4
are identical or different and are a hydrogen atom, a halogen atom, preferably a fluorine, chlorine or bromine atom, a C
1
-C
10
-, preferably C
1
-C
3
-alkyl group or a —NR
2
9
, —SR
9
, —OR
9
, —OSiR
3
9
, —SiR
3
9
or —PR
2
9
radical, in which R
9
is a C
1
-C
10
-, preferably C
1
-C
3
-alkyl group or C
6
-C
10
-, preferably C
6
-C
8
-aryl group, or in the case of radicals containing Si or P also a halogen atom, preferably a chlorine atom, or two adjacent radicals R
3
or R
4
, together with the carbon atoms joining them, form a ring. Particularly preferred ligands are indenyl, fluorenyl and cyclopentadienyl.
R
5
, R
6
, R
7
and R
8
are identical or different and are a hydrogen atom, a halogen atom, a C
1
-C
30
-, preferably C
1
-C
4
-alkyl group, in particular a methyl group or ethyl group, a C
1
-C
10
-fluoroalkyl group, preferably a CF
3
group, a C
6
-C
10
-fluoroaryl group, preferably a pentafluorophenyl group, a C
6
-C
19
-, preferably C
6
-C
8
-aryl group, in particular —CH
2
—C
6
H
5
or —C
6
H
5
, a C
1
-C
10
-, preferably C
1
-C
4
-alkoxy group, in particular a methoxy group, a C
2
-C
10
-, preferably C
2
-C
4
-alkenyl group, a C
7
-C
40
-, preferably C
7
-C
10
-arylalkyl group, a C
8
-C
40
-, preferably C
8
-C
12
-arylalkenyl group or a C
7
-C
40
-, preferably C
7
-C
12
-alkylaryl group, or R
5
and R
6
or R
7
and R
8
, in each case together with the atoms joining them, form a ring.
Especially preferably, R
5
, R
6
and R
7
are a hydrogen atom and R
8
is a phenyl, benzyl, methyl, ethyl, trifluoromethyl or methoxy group, or R
5
and R
7
are a hydrogen atom and R
6
and R
8
are a phenyl, benzyl, ethyl, methyl, trifluoromethyl or methoxy group.
The metallocenes described above can be prepared in accordance with the following general equation:
The cocatalyst is an aluminoxane of the formula II
for the linear type, and/or of the formula (III)
for the cyclic type. In these formulae, R
10
is a C
1
-C
6
-alkyl group, preferably methyl, ethyl or isobutyl, in particular methyl, and n is an integer from 2 to 50, preferably 5 to 40. However, the exact structure of the aluminoxane is not known.
The aluminoxane can be prepared in various ways.
One possibility is careful addition of water to a dilute solution of an aluminum trialkyl by introducing the solution of the aluminum trialkyl, preferably aluminum trimethyl, and the water, in each case in small portions, into a larger amount of an inert solvent initially introduced into the vessel, and awaiting the end of the evolution of gas between each addition.
In another process, finely powdered copper sulfate pentahydrate is suspended in toluene and, in a glass flask under an inert gas at about −20° C., aluminum trialkyl is added in an amount so that about 1 mol of CuSO
4
.5H
2
O is available for every 4 Al atoms. After slow hydrolysis, alkane being split off, the reaction mixture is left at room temperature for 24 to 48 hours, during which it must be cooled if appropriate, so that the temperature does not rise above 30° C. The aluminoxane dissolved in the toluene is then filtered off from the copper sulfate and the solution is concentrated in vacuo. It is assumed that in this preparation process the low molecular weight aluminoxanes condense to form higher oligomers, aluminum trialkyl being split off.
Aluminoxanes are furthermore obtained when aluminum trialkyl, preferably aluminum trimethyl, dissolved in an inert aliphatic or aromatic solvent, preferably heptane or toluene, is reacted with aluminum salts containing water of crystallization, preferably aluminum sulfate, at a temperature of −20 to 100° C. In this procedure, the volume ratio between the solvent and the aluminum trialkyl used is 1:1 to 50:1—preferably 5:1—and the reaction time, which can be monitored by the splitting off of the alkane, is 1 to 200 hours—preferably 10 to 40 hours.
Of the aluminum salts which contain water of crystallization, those which have a high content of water of crystallization are used in particular. Aluminum sulfate hydrate, especially the compounds Al
2
(SO
4
)
3
.16H
2
O and Al
2
(SO
4
)
3
.18H
2
O with the particularly high water of crystallization content o

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