Catalyst – solid sorbent – or support therefor: product or process – Catalyst or precursor therefor – Plural component system comprising a - group i to iv metal...
Reexamination Certificate
2003-06-30
2004-08-31
Lu, Caixia (Department: 1713)
Catalyst, solid sorbent, or support therefor: product or process
Catalyst or precursor therefor
Plural component system comprising a - group i to iv metal...
C502S116000, C502S121000, C502S126000, C526S124800, C526S124900
Reexamination Certificate
active
06784133
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a method of preparing a catalyst for &agr;-olefin polymerization, more particularly, a method of preparing a solid titanium catalyst, the particle size of which can be easily controlled and which is supported by a magnesium-containing supporter.
BACKGROUND ART
Until now, many catalysts for olefin polymerization and the polymerization processes for which they are used have been reported. However, in order to improve the physical properties of a produced polymers, or to produce a polymer having special physical properties, development of novel catalysts is urgent.
Magnesium-containing catalysts for olefin polymerization are suitable for gaseous phase polymerization methods and have high catalyst activity and provide polymers of excellent stereoregularity. In catalysts for gaseous phase polymerization methods, catalyst activity and stereoregularity are important in order to reduce cost. In addition, shape, size, size distribution of catalyst particle, etc. are important. To satisfy catalyst activity and stereoregularity in &agr;-olefin polymerization, several studies have been conducted. Thanks to these studies, the elimination of catalyst residue and atactic composition is not required in most of the present, commercial preparation processes of polyolefin, particularly, polypropylene.
However, nowadays, polypropylene having more improved physical properties, particularly stereoregularity is needed. To obtain these polypropylenes, a novel catalyst is needed.
The mean size of a catalyst particle must also be considered. For example, to produce an impact resistant copolymer having a high content ratio of ethylene to propylene, in which the mean particle size is about 1000 &mgr;m, a catalyst with a mean particle size of about 30 &mgr;m to about 55 &mgr;m is required.
With respect to the size distribution of a catalyst particle, a catalyst having a small particle size is problematic for catalyst transfer, while a catalyst with a large particle size is problematic due to the formation of lumps of polymer during polymerization. Thus, a catalyst having a narrow particle size distribution is required.
Furthermore, a catalyst must have excellent resistance against abrasion generated during the polymerization process and must have a sufficiently high bulk density.
Thus, a polymerization catalyst that can be easily prepared and that has an easily controllable particle size is urgently required.
Many catalysts that are based on magnesium-containing titanium for olefin polymerization and many preparation methods thereof have been reported. In particular, many preparation methods have been reported for olefin polymerization catalysts where a magnesium solution is used and in which the particle size is easily controlled. In the presence of hydrocarbon solvent, magnesium compound is reacted with electron donors such as alcohols, amines, cyclic ethers, carboxy oxides, etc. to provide magnesium solution.
Alcohol is used as an electron donor in U.S. Pat. Nos. 4,330,649, 5,106,807 and Japanese Laid-Open Publication No. SHO 58-83006. Preparation methods of magnesium solutions are reported in U.S. Pat. Nos. 4,315,874, 4,399,054 and 4,071,674.
Tetrahydrofuran is a cyclic ether that has been diversely used as magnesium chloride compound (for example, U.S. Pat. No. 4,482,687), as an additive of cocatalyst (U.S. Pat. No. 4,158,642), and as a solvent (U.S. Pat. No. 4,477,639), etc.
U.S. Pat. Nos. 4,347,158, 4,422,957, 4,425,257, 4,618,661 and 4,680,381 disclose preparation methods of catalysts, comprising: (1) adding Lewis acids, such as aluminum chloride, to a supporter, that is, magnesium chloride to provide a mixture and (2) grinding the mixture.
In the aforementioned inventions, high catalyst activity was achieved. However, uniformity in shape and size, narrowness of size distribution, etc. of catalyst particle and excellent stereoregularity were not achieved.
As described in the above, a novel catalyst for olefin polymerization, which can be simply prepared and which has high polymerization activity, large mean particle size, and narrow particle size distribution, the size of which can be regulated, and thus, can be used to provide highly stereoregular polymer is urgently required.
DISCLOSURE OF THE INVENTION
A feature of the present invention is to provide simpler preparation methods of novel catalysts for olefin polymerization. By controlling the solubility of the reactants, the methods produce catalysts having improved activity and narrow particle size distribution. In addition, polymers prepared using the catalysts have more improved stereoregularity.
In accordance with the feature of the present invention, there is provided a preparation method of titanium catalyst for olefin polymerization, comprising (1) preparing magnesium compound solution by dissolving magnesium halide having no reducing ability and IIIA group element compound in a solvent mixture of cyclic ether, at least one alcohol, phosphorus compound and organosilane with or without hydrocarbon solvent; (2) reacting said magnesium compound solution with titanium compound, silicon compound, tin compound or mixture thereof to produce a supporter; and (3) reacting said supporter with titanium compound and electron donor to produce solid complex titanium catalyst, wherein the particle size and particle size distribution of said catalyst are regulated by controlling solubility of the reactants in said steps (2) and/or (3).
Examples of the magnesium halide compounds having no reducing ability are halogenated magnesium, alkylmagnesium halide, alkoxymagnesium halide, aryloxymagnesium halide and the like. These magnesium halide compounds may be effectively used as mixtures of two or more or in complex with other metals.
Examples of IIIA group element compounds, which are used in combination of magnesium halide compounds in the preparation of magnesium compound solution, are boron halide such as boron fluoride, boron chloride and boron bromide; aluminum halide such as aluminum fluoride, aluminum bromide, aluminum chloride and aluminum iodide. The preferred IIIA group element compound is an aluminum halide, most preferably aluminum chloride. The preferred molar ratio of IIIA group element compound to magnesium compound is 0.25 or less. If the ratio exceeds 0.25, the resultant catalyst is of variable size and reduced activity.
Examples of the hydrocarbon solvents which can be used in the preparation of magnesium compound solution include aliphatic hydrocarbons such as pentane, hexane, heptane, octane, decane and kerosene; alicyclic hydrocarbons such as cyclopentane, methyl cyclopentane, cyclohexane, methylcyclohexane; aromatic hydrocarbons such as benzene, toluene, xylene and ethylbenzene; and halogenated hydrocarbons such as trichloroethylene, carbon tetrachloride and chlorobenzene.
To make magnesium halide compound from magnesium solution, as described in the above, a solvent mixture of cyclic ether, at least one alcohol, phosphorus compound and organosilane is used in the presence or absence of hydrocarbon solvent.
Examples of cyclic ethers which can be used in the preparation of magnesium solution according to the present invention include C
2-15
cyclic ethers such as tetrahydrofuran, 2-methyl tetrahydrofuran and tetrahydropyran. Preferred example of cyclic ether is tetrahydrofuran. If cyclic ether having carbon atom higher than 15 is used, it is difficult to prepare magnesium solution.
Examples of alcohols which can be used in the preparation of magnesium solution according to the present invention include C
1-20
alcohols such as methanol, ethanol, propanol, butanol, pentanol, hexanol, octanol, decanol, dodecanol, octadecylalcohol, benzylalcohol, phenylethylalcohol, isopropylbenzylalcohol, and cumylalcohol. Preferred examples of alcohols are C
1-12
alcohols. If alcohols having carbon atom higher than 20 is used, it is difficult to prepare magnesium solution.
Mean size and size distribution of catalyst particle which is prepared differ depending upon the ratio of alcohol to cyclic ether, etc.
Kim Il Seop
Ro Ki Su
Shin Moon Young
Clark Paul T.
Clark & Elbing LLP
Lu Caixia
Samsung Atofina Co. Ltd.
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