Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Patent
1996-06-26
1998-05-26
Wu, David W.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Polymers from only ethylenic monomers or processes of...
526129, 526153, 526160, 526352, 526943, 502117, 502155, C08F 464, C08F 206
Patent
active
057566070
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a process for the preparation of homopolymers of ethylene or copolymers of ethylene with other olefins or mixtures thereof by suspension polymerization in the presence of catalyst systems.
2. Description of the Related Art
For example, EP-A 294 942 discloses that metallocene catalysts may be supported in order to obtain polymers having improved morphology. However, this reduces the productivity on the one hand and, on the other hand, wall deposits and the formation of lumps occur during the polymerization.
One preparation process for polymers of ethylene is suspension polymerization. This can be carried out by the Phillips PF (particle forming) process in a continuously operated loop reactor, as described, for example, in U.S. Pat. No. 3,242,150 and U.S. Pat. No. 3,248,179. However, products having a broad molecular weight distribution are formed here.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a process for the preparation of homopolymers of ethylene or copolymers of ethylene with other olefins or mixtures thereof by suspension polymerization, which process does not have the stated disadvantages.
We have found that this object is achieved by a process for the preparation of homopolymers of ethylene or copolymers of ethylene with other olefins or mixtures thereof by suspension polymerization in the presence of catalyst systems, wherein the catalyst systems used are those which contain, as active components,
We have also found the homopolymers of ethylene or copolymers of ethylene with other olefins or mixtures thereof, which homopolymers and copolymers are obtainable thereby.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The novel process is used for the preparation of homopolymers of ethylene or copolymers of ethylene or mixtures thereof. Preferred copolymers of ethylene are those in which alk-1-enes, preferably straight-chain branched C.sub.3 -C.sub.6 -alk-1-enes, in particular 1-butene and 1-hexene, are used as comonomers. It is also possible to use a plurality of different monomers. The amount of comonomers here is from 0.1 to 80, preferably from 5 to 50, % by weight, based on the total amount of monomers.
In the novel process, the homo- or copolymers of ethylene are prepared by suspension polymerization in the presence of a catalyst system.
This catalyst system contains, as component A), a finely divided carrier which is treated with trialkylaluminum and preferably has a particle diameter of from 1 to 200 .mu.m, in particular from 30 to 70 .mu.m. Suitable carrier materials are, for example, silica gels of the formula SiO.aAl.sub.2 O.sub.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. Silica gels which have a water content of from 2 to 12% by weight (determined as the weight loss on heating up to 200.degree. C. at 10 K/min) are preferred.
Other inorganic oxides, such as Al.sub.2 O.sub.3, TiO.sub.2 or ThO.sub.2, can also be used as carriers.
The treatment of the carrier with trialkylaluminum is carried out with an amount of from 0.1 to 3, preferably from 0.3 to 1.2, in particular from 0.5 to 0.8, mol/(kg of carrier.times.% water content). Trimethylaluminum is preferably used.
This catalyst system contains, as component B), a metallocene complex, preferably of metals of subgroups IV and V of the Periodic Table.
Particularly suitable metallocene complexes are of the general formula I: ##STR1## where M is titanium, zirconium, hafnium, vanadium, niobium or tantalum, -alkyl, C.sub.6 -C.sub.15 -aryl or --OR.sup.6, arylalkyl, fluoroalkyl or fluoroaryl, each of 1 to 10 carbon atoms in the alkyl radical and 6 to 20 carbon atoms in the aryl radical, to 7-membered cycloalkyl which in turn may carry a C.sub.1 -C.sub.6 -alkyl as a substituent, C.sub.6 -C.sub.15 -aryl or arylalkyl, where two neighboring radicals together may furthermore form a cyclic group of 4 to
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Gortz Hans-Helmut
Langhauser Franz
Lilge Dieter
Lux Martin
Micklitz Wolfgang
BASF - Aktiengesellschaft
Wu David W.
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