Catalyst system for the Ziegler-Natta polymerization of olefins

Details Catalyst system for the Ziegler-Natta polymerization of olefins Catalyst system for the Ziegler-Natta polymerization of olefins

2001-03-08

2003-03-18

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...

C526S348000, C526S124300, C526S128000, C526S142000, C526S125300, C502S132000, C502S103000, C502S118000, C502S125000, C502S127000, C556S009000, C556S027000, C556S051000

Reexamination Certificate

active

06534606

ABSTRACT:

The invention relates to novel catalyst systems characterized in that aluminium alkyl complexes of the formula (I), such as described in DE 19753135 applied to magnesium chloride, SiO
2
or SiO
2
in combination with MgCl
2
as support in the presence of titanium halides or vanadium halides act both as cocatalysts and as stereo-selectivity promoters in heterogeneous polymerizations of &agr;-olefins,
where
X
1
is NH, NH
2
*, NH—A*, NH—SiA
3
*, N—A, NSiA
3
, N(A)
2
*, N(SiA
3
)
2
*, O, OSiA
2
, OA*, OSiA
3
*, OAryl*, S, SSiA
2
, SA*, SSiA
3
*, PA, PSiA
3
, P(A)
2
*, P(SiA
3
)
2
* or a single bond,
X
2
is NH, N—A, NSiA
3
, O, OSiA
2
, S, SSiA
2
, PA or X
1
coordinated to Al(R
1
)
3
, or a single bond,
R
1
is H; Hal when n=0; A, if desired covalently bound to Al; Si(A)
3
when X
1
=O,
R
2
is A, if desired covalently bound to Al;
 CH
2
—CH═CH, CH
2
—C≡C when Z
1
=H;
R
3
and R
4
are each, independently of one another, a bond or R
2
or Si(A)
3
or Si(A)
2
,
Z
1
is a bond or H bound to R
2
,
Z
2
is a bond or H bound to R
2
and R
3
, where
A is branched or unbranched C
1
-C
7
-alkyl, -alkylidene or -alkenylidene,
Aryl is phenyl, naphthyl, indenyl, fluorenyl,
Hal is F, Cl,
and, independently of one another,
n is 0 or 1,
m is 0 or 1,
p is 0 or 1,
q is 1 or 2,
l is 0 or 1,
where coordinate bonds can exist between X
1
, X
2
and Al, and R
1
, R
2
, R
3
, R
4
, X
1
, X
2
, Z
1
and Z
2
can, in each case independently of one another at different positions in the molecule, assume all meanings and X
1
can assume only the meanings denoted by “*” when 1=0 and R
1
, R
2
, R
3
or R
4
are not present.
Ziegler-Natta-catalysed polymerization is a polymerization method which has been improved over a number of generations since the initial work by Ziegler and Natta in the 1950s. Seeking to increase both the activity and the stereoselectivity has been the driving force for the continuous development of the catalyst system. The system established at the present time is based on the use of a multicomponent catalyst. In addition to the support material, this comprises as actual catalyst a transition metal compound, e.g. a titanium compound, which is activated only by addition of an aluminium-containing cocatalyst. In addition, further constituents such as internal and external donors are necessary. The use of an internal donor prevents agglomeration of the catalytically active species, while the external donor improves the stereospecificity when using prochiral olefins. Thus, in a polymerization using liquid propene, the system MgCl
2
/ester/TiCl
4
/AlEt
3
/PhSi(OEt)
3
makes it possible to achieve a productivity of 600 [kg
pp
/g
Ti
] combined with an isotacticity of 98%. These catalyst systems save the costly removal of catalyst residues and the complicated extraction of atactic material from the polyolefins produced. The understanding which has now been gained regarding the relationship between catalyst and polymer morphology makes it possible to control the polymer morphology during the polymerization process, which eliminates additional processing steps such as extrusion and granulation. These advances have for the first time made it possible to carry out solvent-free gas-phase polymerization and bulk polymerization and have led to substantial simplifications in the case of suspension polymerization. [P. Galli, J. C. Haylock,
Makromol. Chem., Macromol. Symp.
1992, 63, 19-54; P. Corradini, V. Buscio, G. Guerra, in
Comprehensive Polymer Science,
Vol. 4, G. Allen (Ed.), Pergamon Press, 1999, p. 29; C. Jenny, P. Maddox,
Solid State
&
Mat. Science
1988, 3, 94; K. Soga, T. Shiono,
Progress in Polymer Science
1997, 22, 1503].
DE 19753135 describes a series of aluminium compounds which have an intramolecular donor side chain, e.g. an amino-, thio- or oxo-coordinated side chain, and can be prepared by methods known to those skilled in the art for preparing organometallic compounds. These aluminium compounds act as cocatalytically activating components in Ziegler-Natta catalysts for the polymerization of ethylene. However, the polymerization of propylene or higher &agr;-olefins cannot be carried out successfully using the catalyst systems described in this patent application. Furthermore, the catalyst systems used there did not include a catalyst support, which makes them difficult or impossible to use in industrial plants and additionally does not allow the desired polymer morphology to be set.
Apart from the continual striving for more active and more selective catalyst systems, the following aspects are in need of improvement:
a) The catalyst systems used in industry comprise highly pyrophoric, reactive, volatile aluminium alkyl compounds as cocatalysts, in particular triethylaluminium. These compounds are highly sensitive to impurities in the reaction medium, for example to residual moisture in the monomers to be polymerized. In addition, the safe handling of such highly pyrophoric and volatile compounds requires expensive safety containers for storage and transport under absolute exclusion of oxygen and moisture. Furthermore, the industrial plants for catalyst preparation and polymerization have to be able to cope with these problems. This is, in particular, a problem for industrially relatively undeveloped countries and regions in which high temperatures and high atmospheric humidity prevail as a result of the climate.
b) To be able to achieve further increases in the yield of polymers in olefin polymerization, catalyst systems having higher activities have to be tailored and developed. The activity increase should be able to be achieved by optimization of the cocatalyst, since it converts the catalyst into the actual catalytically active species.
c) To achieve high stereoselectivities in the Ziegler-Natta catalysis of prochiral olefins, additional costly external donors such as PhSi(OEt)
3
have to be used. The properties (tacticity and molecular weight distribution) of the polymers obtained using external donors have hitherto not been able to be optimized fully satisfactorily, so that there is a continuing need for polymers having improved properties.
d) Since the cocatalyst in Ziegler-Natta catalysts is usually used in a large excess relative to the catalyst and is thus the most costly component, there is great interest in reducing the cocatalyst/catalyst ratio while retaining the activities.
It is therefore an object of the present invention to provide catalyst systems which do not have the disadvantages listed under a), b), c) and d) and can be used both for the polymerization of ethylene and of propylene and higher &agr;-olefins. Another object of the present invention is to provide corresponding catalyst systems which are bound to suitable supports, simply and inexpensively. The catalyst systems of the present invention should be usable in industrial plants under simple conditions with a relatively small cocatalyst/catalyst ratio and should at the same time have activities which are better than those of previously known systems. Another object of the present invention is to provide corresponding catalyst systems which are less sensitive to impurities, in particular moisture.
Upon further study of the specification and appended claims, further objects and advantages of this invention will become apparent to those skilled in the art.
The invention includes catalyst systems comprising
a) aluminium alkyl complexes of the formula (I)
 where
X
1
is NH, NH
2
*, NH—A*, NH—SiA
3
*, N—A, NSiA
3
, N(A)
2
*, N(SiA
3
)
2
*, O, OSiA
2
, OA*, OSiA
3
*, OAryl*, S, SSiA
2
, SA*, SSiA
3
*, PA, PSiA
3
, P(A)
2
*, P(SiA
3
)
2
* or a single bond,
X
2
is NH, N—A, NSiA
3
, O, OSiA
2
, S, SSiA
2
, PA or X
1
coordinated to Al(R
1
)
3
, or a single bond,
R
1
is H; Hal when n=0; A, if desired covalently bound to Al; Si(A)
3
when X
1
=O,
R
2
is A, if desired covalently bound to Al;
 CH
2
—CH═CH, CH
2
—C≡C when Z
1
=H;
R
3
and R
4
are each, independently of one another, a bond or R
2
o

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