Preparation of polymers of alkenes by suspension polymerization

Details Preparation of polymers of alkenes by suspension polymerization Preparation of polymers of alkenes by suspension polymerization

1998-08-04

2001-12-04

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...

C526S132000, C526S160000, C526S943000, C502S117000

Reexamination Certificate

active

06326444

ABSTRACT:

The present invention relates to a process for the preparation of polymers of alkenes by suspension polymerization in the presence of catalyst systems.
The present invention furthermore relates to the resulting polymers of alkenes, the use of these polymers for the production of fibers, films and moldings and the fibers, films and moldings obtainable therefrom.
A preparation process for polymers of ethylene by suspension polymerization is described, for example, in WO 95/18160. Here, however, the dry catalyst is pyrophoric and already active with respect to polymerization.
WO 91/09882 discloses the preparation of a supported, cationic metallocene catalyst by applying the reaction mixture of a dialkymetallocene with an ionic compound, which has a Brönsted acid as the cation and a noncoordinating opposite ion, such as tetrakis(pentafluorophenyl)borate as the anion to an inorganic carrier. Here too, an active catalyst is obtained.
Similar supported catalyst systems are also disclosed in WO 94/03506 and WO 95/14044.
EP-A 628 574 describes supported catalyst systems in which a metallocene dihalide is reacted with an alkylaluminum in the presence of a hydridoborate and this solution, which is active with respect to polymerization, is applied to a carrier.
Such already active catalysts readily give rise to problems in the metering of the catalyst into the reactor.
A catalyst which is still inactive and can be activated only subsequently, for example during metering or only in the reactor, is therefore advantageous.
EP-A 613 908 discloses supported metallocene catalyst systems, some of which are not activated until they are in the reactor. Here, however, the polymers formed have a broad molecular weight distribution M
w
/M
n
.
WO 95/15815 describes catalysts which are obtained by applying a metallocene dichloride and a borate to a crosslinked polymer as a carrier. The use of deactivated inorganic carriers gives catalysts which, after activation in the polymerization reactor, have either only slight activity or no activity at all.
It is an object of the present invention to provide a process for the preparation of polymers of alkenes by suspension polymerization, which process does not have the stated disadvantages and in which in particular the catalyst system can be activated at any desired time, the catalyst system is air- and moisture-insensitive, can be stored for a long time and is not pyrophoric and the polymers formed have a narrow molecular weight distribution.
We have found that this object is achieved by a process for the preparation of polymers of alkenes by suspension polymerization in the presence of catalyst systems, wherein the catalyst systems used are supported catalyst systems obtainable by
A) reaction of an inorganic carrier with a metal compound of the general formula I
M
1
(R
1
)
r
(R
2
)
s
(R
3
)
t
(R
4
)
u
  I
where
M
1
is an alkali metal, an alkaline earth metal or a metal of main group III or IV of the Periodic Table,
R
1
is hydrogen, C
1
-C
10
-alkyl, C
6
-C
15
-aryl, alkylaryl or arylalkyl, each having 1 to 10 carbon atoms in the alkyl radical and 6 to 20 carbon atoms in the aryl radical,
R
2
to R
4
are each hydrogen, halogen, C
1
-C
10
-alkyl, C
6
-C
15
-aryl, alkylaryl, arylalkyl, alkoxy or dialkylamino, each having 1 to 10 carbon atoms in the alkyl radical and 6 to 20 carbon atoms in the aryl radical,
r is an integer from 1 to 4 and
s, t and u are integers from 0 to 3, the sum r+s+t+u corresponding to the valency of M
1
,
B) reaction of the material obtained according to A) with a metallocene complex in its metal dihalide form and a compound forming metallocenium ions and
C) subsequent reaction with a metal compound of the general formula II
M
2
(R
5
)
o
(R
6
)
p
(R
7
)
q
  II
in which
M
2
is an alkali metal, an alkaline earth metal or a metal of main group III of the Periodic Table,
R
5
is hydrogen, C
1
-C
10
-alkyl, C
6
-C
15
-aryl, alkylaryl or arylalkyl, each having 1 to 10 carbon atoms in the alkyl radical and 6 to 20 carbon atoms in the aryl radical,
R
6
and R
7
are each hydrogen, halogen, C
1
-C
10
-alkyl, C
6
-C
15
-aryl, alkylaryl, arylalkyl or alkoxy, each having 1 to 10 carbon atoms in the alkyl radical and 6 to 20 carbon atoms in the aryl radical,
o is an integer from 1 to 3 and
p and q are integers from 0 to 2, the sum o+p+q corresponding to the valency of M
2
.
We have also found the polymers of alkenes which are obtainable thereby, their use for the production of fibers, films and moldings and the fibers, films and moldings obtainable therefrom.
The novel process is used for the preparation of polymers of alkenes. The term polymers is understood as meaning both homopolymers and copolymers. Particularly suitable alkenes are alk-1-enes, preferably ethylene and propylene, in particular ethylene. Alk-1-enes are also suitable as comonomers, preferably straight-chain C
4
-C
10
-alk-1-enes, in particular but-1-ene, hex-1-ene and oct-1-ene. However, it is also possible to use other alkenes, for example cycloolefins or higher alkenes.
Supported catalyst systems which are obtainable by reacting an inorganic carrier with a metal compound of the general formula I in a first stage A) are used as supported catalyst systems.
The carriers used are preferably finely divided solids whose particle diameters are from 1 to 200 &mgr;m, in particular from 30 to 70 &mgr;m.
Examples of suitable carriers are silica gels, preferably those of the formula SiO
2
.a Al
2
O
3
, where a is from 0 to 2, preferably from 0 to 0.5; these are therefore aluminosilicates or silica. Such products are commercially available, for example Silica Gel 332 from Grace.
Other inorganic compounds, such as Al
2
O
3
or MgCl
2
, or mixtures containing these compounds may also be used as carriers.
Preferred metal compounds of the general formula I are those in which M
1
is a metal of main group III of the Periodic Table, in particular aluminum, R
1
is C
1
-C
10
-alkyl and R
2
to R
4
are each C
1
-C
10
-alkyl. For the particularly preferred case where M
1
is aluminum, u is zero and R
1
to R
3
have in particular the same meaning, preferably methyl, ethyl, isobutyl or hexyl, preferably isobutyl.
The metal compound of the general formula I is preferably added as a solution to a suspension of the carrier. Particularly suitable solvents or suspending agents are hydrocarbons, such as heptane. The amount of metal compound I can be varied within wide limits, the minimum amount depending on the number of hydroxyl groups of the carrier. The temperatures, reaction times and pressures are not critical per se, temperatures of from 0 to 80° C. and reaction times of from 0.1 to 48 hours being preferred.
It has proven suitable to remove the excess metal compound I by thorough washing, for example with hydrocarbons, such as pentane or hexane, after the carrier pretreatment and to dry the carrier.
The material thus prepared can be stored for up to 6 months and is not pyrophoric.
This material is then reacted, in a further stage B), with a metallocene complex in its metal dihalide form and a compound forming metallocenium ions.
Examples of suitable metallocene complexes are compounds of the general formula III:
where
M is titanium, zirconium, hafnium, vanadium, niobium or tantalum,
x is fluorine, chlorine, bromine or iodine,
R
8
to R
12
are each hydrogen, C
1
-C
10
-alkyl, 5- to 7-membered cycloalkyl which in turn may carry a C
1
-C
10
-alkyl as a substituent, C
6
-C
15
-aryl or arylalkyl, where two adjacent radicals together may furthermore form a cyclic group of 4 to 15 carbon atoms, or Si(R
13
)
3
,
where
R
13
is C
1
-C
10
-alkyl, C
3
-C
10
-cycloalkyl or C
6
-C
15
-aryl,
where
14
to R
18
are each hydrogen, C
1
-C
10
-alkyl, 5- to 7-membered cycloalkyl which in turn may carry a C
1
-C
10
-alkyl as a substituent, C
6
-C
15
-aryl or arylalkyl, where two adjacent radicals together may furthermore form a cyclic group of 4 to 15 carbon atoms, or Si(R
19
)
3
, where
R
19
is C
1
-C
10
-alkyl, C
6
-C
15
-aryl or C
3
-C
10
-cycloalkyl, or R
11
and Z

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