Stoves and furnaces – Liquid heater
Reexamination Certificate
2002-03-27
2004-10-05
Choi, Ling-Siu (Department: 1713)
Stoves and furnaces
Liquid heater
C526S348000, C526S123100, C526S124300, C526S158000, C526S125300, C502S103000, C502S133000, C502S116000
Reexamination Certificate
active
06799568
ABSTRACT:
The invention is directed to a process for the preparation of a catalyst component for the polymerization of an olefin.
Catalyst components on a support for the preparation of polyolefins have a high activity and a high stereospecificity. These catalyst components are already known for a long time. Essential elements for the preparation of such catalyst components are a magnesium-containing support and a titanium compound attached thereto. For the polymerization of olefins also an alkylaluminum compound is needed as a cocatalyst.
High activity supported catalyst components are the most frequently used catalyst components for the polymerization of olefins, such as for instance propylene. By the high activity of the catalyst component a high yield of the polyolefin is obtained per weight percentage of the titanium compound in the catalyst component. Therefore it is no longer needed to remove the catalyst component from the polyolefin produced.
There are several methods to prepare the magnesium-containing support of the catalyst component. It is for instance possible to grind the magnesium-containing support, spraydrying it or to precipitate the magnesium-containing support. The magnesium-containing support can further be treated with a halogenating compound to prepare the magnesium-containing support. Several other methods to prepare magnesium-containing supports are for instance described by E. P. Moore (Jr.), Polypropylene Handbook, Hansen Publishers, 1996, p. 22.
A process for the preparation of such a supported catalyst component is for instance described in WO-A-96/32427. In this patent application a process for the preparation of a catalyst component for the polymerization of an olefin is described. In the preparation of the catalyst component a magnesium compound is contacted with a titanium compound wherein the magnesium compound is obtained by:
a) contacting metallic magnesium with an aromatic halide RX, where R is an aromatic group containing up to 20 carbon atoms and X is a halide, whereupon the resulting dissolved reaction product I is separated from the solid residual products and whereafter,
b) an alkoxy group or aryloxy group containing silane compound is added to the obtained reaction product I at a temperature of from −20 to 20° C., whereupon the precipitate formed is purified to obtain reaction product II,
which reaction product II is subsequently, during a step c), is contacted with TiCl
4
, and the resulting product is purified to obtain the catalyst component.
Although the performance of this catalyst component is very good and this catalyst component already shows a high activity and selectivity, a more improved catalyst component is obtained by the process of the present invention wherein in step b) the silane compound and reaction product I are introduced simultaneously to a mixing device.
Here and hereafter “simultaneous introduction” means the introduction of reaction product I and the silane compound in such a way that the Mg/Si ratio does not substantially vary during the introduction of these compounds to the mixing device.
This process has the advantage that the morphology of the catalyst particles improves; especially for the larger catalyst particles. Here and hereafter ‘morphology’ does not only refer to the shape of the catalyst particles, but also to the particle size distribution and the bulk density of the catalyst particles.
The polyolefin powder produced in the polymerization by using the catalyst component has the same morphology as the catalyst component; this is a known effect and is called the “replica effect” (S. van der Ven, Polypropylene and other Polyolefins, Elsevier 1990, p. 8-10). Using the catalyst compound prepared according to the process of the invention almost round polymer particles are obtained with a length/diameter ratio (1/d) smaller than 2 and a good powder flowability, while according to WO-A-96/32427 elongated polymer particles are obtained with a 1/d of more than 2.5.
During step b) the dissolved reaction product I, obtained after carrying out step a), is brought into contact with an alkoxy group or aryloxy group containing silane compound in such a way that reaction product I and the silane compound are introduced simultaneously to the mixing device.
The mixing device can have various forms; the mixing device can be a mixing device in which the silane compound is premixed with reaction product I, but the mixing device can also be the reactor in which reaction product II is formed.
The mixing device for simultaneously premixing the silane compound and reaction product I can be a mixing device in which the premixing takes place in a dynamic or a static way. Premixing in a dynamic way can take place by, for instance, mixing, stirring, shaking and by the use of ultrasonic waves. Premixing in a static way can take place in, for instance, a static mixer or in a tube wherein the silane compound and reaction product I are contacted. For the preparation of the catalyst component in big amounts both static and dynamic mixing can be used. Premixing in a dynamic way is preferably used when the catalyst component is prepared in small amounts. For the preparation of the catalyst component in big amounts preferably a static mixer is used for premixing the silane compound and reaction product I. Preferably, the silane compound and reaction product I are premixed before the mixture is introduced to the reactor wherein reaction product II is formed. In this way the catalyst component formed gives polymer particles with the best morphology.
Premixing is performed during 0.1 to 300 seconds; preferably during 1 to 50 seconds.
The temperature during the premixing is between 0 and 80° C.; preferably between 10 and 50° C.
The silane compound and reaction product I can be continuously or batch-wise introduced to the mixing device. Preferably, the silane compound and reaction product I are introduced continuously to the mixing device.
The formation of reaction product II normally takes place at a temperature between −20 and 100° C.; preferably at a temperature of from 0 to 80° C.
Preferably, reaction product I is contacted with the alkoxy group or aryloxy group containing silane compound in the presence of an inert hydrocarbon solvent such as the solvents mentioned further as dispersant in the discussion of step a). The solvent can be a solvent for the silane compound, a dispersant for reaction product I or be present in the reactor wherein reaction product II is collected. Combinations of these three possibilities are also possible.
Preferably, the reactor wherein reaction product II is obtained, is a stirred reactor.
The Si/Mg molar ratio during step b) may vary from 0.2 to 20. Preferably, the Si/Mg molar ratio is from 0.4 to 1.0.
The product from step b), reaction product II, is usually purified by rinsing with an inert hydrocarbon solvent and then used for the further preparation of the catalyst component in step c).
The following examples of alkoxy group or aryloxy group containing silane compounds may be mentioned: tetramethoxysilane, tetraethoxysilane, tetrabutoxysilane, tetraisobutoxysilane, tetraphenoxysilane, tetra(p-methylphenoxy)silane, tetrabenzyloxysilane, methyltrimethoxysilane, methyltriethoxysilane, methyltributoxysilane, methyltriphenoxysilane, methyltriphenoxysilane, ethyltriethoxysilane, ethyltriisobutoxysilane, ethyltriphenoxysilane, butyltrimethoxysilane, butyltriethoxysilane, butyltributoxysilane, butyltriphenoxysilane, isobutyltriisobutoxysilane, vinyltriethyoxysilane, allyltrimethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, benzyltriphenoxysilane, methyltriallyloxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, dimethyldiisopropyloxysilane, dimethyldibutoxysilane, dimethyldihexyloxysilane, dimethyldiphenoxysilane, diethyldiethoxysilane, diethyldiisobutoxysilane, diethyldiphenoxysilane, dibutyldiisopropyloxysilane, dibutyldibutoxysilane, dibutyldiphenoxysilane, diisobutyldiethoxysilane, diisobutyldiisobutoxysilane, diphenyldimethoxysilane, diphenyldiethoxysilane, diphenyldibutoxysil
Bukatov Gennady D.
Sergeev Sergei A.
Zakharov Vladimir A.
Choi Ling-Siu
DSM N.V.
Pillsbury & Winthrop LLP
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