Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Reexamination Certificate
1994-11-10
2001-11-20
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...
C526S116000, C526S114000, C526S119000, C526S125100, C526S124100, C526S142000, C526S348000, C526S352000
Reexamination Certificate
active
06320003
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a method for producing a polyolefin. More particularly, this invention relates to a method which enables to obtain a polymer having a desired molecular weight distribution and a good configuration of particles while maintaining high catalytic activity in polymerizing at least one olefin.
BACKGROUND OF THE INVENTION
It is already known to use a catalyst system comprising a transition metal compound and an organometallic compound for low-pressure polymerization of olefins. In recent years, a large number of proposals have been made for producing, as a highly active catalyst, a solid catalyst component comprising magnesium, titanium and halogen as main components.
However, to obtain higher productivity, it is very important from the industrial viewpoint to aim not only at high catalytic activity but also at improving the particle size, the bulk density and the like of polymer particles. At the same time, it is now demanded to optionally control the molecular weight distribution of the resulting polymer for satisfying the diversification of qualities.
In Japanese Examined Patent Publication No. 39714/1977, the present inventors previously proposed a polymerization method which can produce a polyolefin having a desired molecular weight distribution while maintaining high catalytic activities by employing a catalyst system comprising a reaction product of metal magnesium, a hydroxylated organic compound, an organic oxidized compound of a transition metal, a halogen-containing compound of a transition metal and an aluminum halide, and an organometallic compound, but it was still insufficient from the viewpoint of improvement in the particle properties such as the particle size, bulk density and the like of polymer particles.
A serious problem which usually occurs in conducting polymerization is soiling of a reactor (deposition of a solid polymer on the inner surface of the reactor), whereby it is necessary to stop the polymerization operation to remove the deposition. Such a problem tends to be significant particularly in the production of a resin having a broad molecular weight distribution such as the one which is to be used for blow molding, extrusion molding or the like.
On the other hand, if the particle size distribution is broad, various problems are likely to occur during the production of a polyolefin, for example, in the steps of polymerization, separation of the particles from the polymer slurry, drying of the powder and transportation of the powder, and in some cases, long-term continuous production becomes impossible. Further, when a polymer is obtained by multi-stage polymerization, if the particle size distribution of the polymer particles is broad, classification of the powder is likely to occur after the drying step, i.e. at the stage where additives are added or at the stage of transportation. The physical properties differ from one particle size to another and the adverse effects to the quality can sometimes not be ignored. Further, in a gas phase polymerization, particle properties are particularly important in view of productivity because, if the powder properties are poor, blocking or the like of polymer particles occurs in the polymerization reactor.
Under these circumstances, in Japanese Examined Patent Publication No. 48682/1987, the present inventors previously proposed a method for improving or eliminating the above defects. In this method, a catalyst system is employed which comprises a solid catalyst component (A) obtained by reacting metal magnesium and a hydroxylated organic compound, or an oxygen-containing organic compound or halogen-containing compound of magnesium, with an oxygen-containing organic compound or halogen-containing compound of titanium, an oxygen-containing organic compound or halogen-containing compound of zirconium, a silicon compound, and an aluminum halide compound, and a catalyst component (B) of an organometallic compound.
However, this method could not lead to an improvement in the particle size distribution.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a method for producing a polyolefin, whereby a polymer having a good particle shape and a controlled molecular weight distribution can be obtained while maintaining the high catalytic activities.
The present inventors have now found that the above object can be attained by conducting the polymerization of an olefin in the presence of a novel catalyst system, and have accomplished the present invention on the basis of the discovery.
The present invention provides a method for producing a polyolefin in the presence of a catalyst comprising a transition metal compound and an organometallic compound, wherein a catalyst system is used which comprises:
(A) a solid catalyst component prepared by reacting a homogeneous solution containing
(I) at least one member selected from the group consisting of metal magnesium and a hydroxylated organic compound, and oxygen-containing organic compounds of magnesium,
(II) at least one zirconium compound selected from the group consisting of oxygen-containing organic compounds and halogen-containing compounds of zirconium, and
(III) at least one silicon compound selected from the group consisting of polysiloxanes and silanes, with
(IV) at least one organoaluminum halide compound to obtain a solid product, isolating the solid product, and reacting this solid product with
(V) at least one halogen-containing compound of titanium, and
(B) at least one catalyst component selected from the group consisting of organoaluminum compounds.
The present invention also provides a method for producing a polyolefin in the presence of a catalyst comprising a transition metal compound and an organometallic compound, wherein a catalyst system is used which comprises:
(A) a solid catalyst component prepared by reacting a homogeneous solution containing
(I) at least one member selected from the group consisting of metal magnesium and a hydroxylated organic compound, and oxygen-containing organic compounds of magnesium,
(II) at least one zirconium compound selected from the group consisting of oxygen-containing organic compounds and halogen-containing compounds of zirconium, and
(III) at least one silicon comound selected from the group consisting of polysiloxanes and silanes, with
(IV) at least one organoaluminum halide compound to obtain a solid product, isolating the solid product, and reacting this solid product with
(V) at least one halogen-containing compound of titanium, and
(VI) at least one compound selected from the group consisting of halogen-containing compounds of Groups IIIb and IVb of the Periodic Table, and
(B) at least one catalyst component selected from the group consisting of organoaluminum compounds.
DETAILED DESCRIPTION OF THE INVENTION AND PREFERRED EMBODIMENTS
Now, the present invention will be described in detail with reference to the preferred embodiments.
Metal magnesium and a hydroxylated organic compound, and oxygen-containing compounds of magnesium that are used as reactant (I) in the present invention will be described below.
Firstly, when metal magnesium and a hydroxylated organic compound are used, metal magnesium can take any form such as powdery form, granular form, foil form, or ribbon form, and as the hydroxylated organic compound, alcohols, organosilanols, and phenols are suitable.
As the alcohols, linear or branched aliphatic alcohols or alicyclic alcohols having 1 to 18 carbon atoms can be used. Specific examples include methanol, ethanol, n-propanol, i-propanol, n-butanol, i-butanol, n-hexanol, 2-ethylhexanol, n-octanol, n-stearyl alcohol, cyclopentanol, cyclohexanol, and ethylene glycol.
The organosilanols are those having at least one hydroxyl group and an organic group selected from an alkyl group, a cycloalkyl group, an arylalkyl group, an aryl group, and an alkylaryl group with 1 to 12, preferably 1 to 6, carbon atoms. For example, trimethylsilanol, triethylsilanol, triphenylsilanol, and t-butyldimethylsilanol may be mentioned.
As phenols, phenol,
Kondo Yozo
Mori Mitsuhiro
Naito Yutaka
Nishimura Sadaki
Choi Ling-Siu
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Tosoh Corporation
Wu David W.
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