Method of homo- or co-polymerization of &agr;-olefin

Details Method of homo- or co-polymerization of &agr;-olefin Method of homo- or co-polymerization of &agr;-olefin

2001-05-30

2003-05-06

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...

C526S348000, C526S125300, C526S128000, C526S125100, C526S124900, C526S139000, C526S140000, C526S154000, C526S158000, C502S118000, C502S121000, C502S125000, C502S116000, C502S103000

Reexamination Certificate

active

06559250

ABSTRACT:

TECHNICAL FIELD
The present invention relates to a method of homo- or co-polymerization of &agr;-olefins (hereinafter (co)polymerization), or more particularly to a method for producing olefin (co)polymers of high stereoregularity at a high rate of yields, while controlling the polymer's molecular weight distribution.
BACKGROUND OF INVENTION
In general, the olefin polymers produced with MgCl
2
-supported catalysts have a narrow distribution of molecular weights. Many efforts have been made to broaden the distribution of molecular weights, so as to improve fluidity of the products produced by these catalysts at the time of processing. For this purpose, a method has been in wide use in which olefin polymers of different distributions of molecular weights are first made in each different polymerization reactor and later mixed, but this has disadvantages in that it requires much time and effort, and the product is often found to be very uneven. In a recent report from Mitsui Petrochemical of Japan (Korean Patent Publication No. 10-1993-000665), a method has been proposed in which olefin polymers with a wider distribution of molecular weights are produced by the use of two particular electron donors, from which homopolyolefins having a melt flow rate (MFR) of greater than 31.6 are respectively polymerized in the same polymerization conditions. In this case, however, the catalytic activity is too low to be commercialized, and not only is its molecular weight distribution difficult to control, but the hydrogen reactivity, which controls the molecular weight distribution of the polymers, is so low as to pose many limitations on the management of its processing.
Meanwhile, many other techniques of prior art are known to produce (co)polymers of high stereoregularity by the use of a solid complex titanium component containing at least magnesium treated with electron donors, and also titanium and a halogen, as a titanium catalyst for (co)polymerization of &agr;-olefins which contains more than three atoms of carbon (for example Japanese Patent Laid-Open Nos. 73-16986 and 73-16987; German Patent Laid-Open Nos. 2,153,520, 2,230,672, 2,230,728, 2,230,752, and 2,553,104).
These references reveal the use of mixture components of particular catalysts and the process for forming these catalysts. As is well known, the characteristics of these catalysts, containing solid complex titanium components, vary from catalyst to catalyst accordant with the different mixtures of components, different combinations of processes for formation, and different combinations of these conditions. Therefore, it is almost impossible to expect similar results from the catalysts produced under a given combination of conditions. Often, a catalyst having extremely defective properties is produced. When proper external electron donors are not used, it is also often true that such characteristics as catalytic activity or stereoregularity of polymers do not turn out to be adequate even though the catalyst is made under proper conditions.
The solid complex titanium component containing at least magnesium, titanium, and halogen is no exception. In (co)polymerization of &agr;-olefins containing more than three atoms of carbon in the presence of hydrogen and with the use of a catalyst composed of titanium and an organometallic compound of metals belonging to Groups I through IV of the Periodic Table, if a catalyst composed of titanium trichloride obtained by reducing titanium tetrachloride using metallic aluminum, hydrogen, or an organic aluminum compound is used along with such electron donors as are known to suppress the formation of amorphous (co)polymers, the effects vary depending upon the electron donors used. The cause for this is accepted to be that the electron donors are not merely added, but rather they are combined with the magnesium and titanium compounds, electronically and sterically, thereby fundamentally altering the microstructure of the solid complex catalyst.
New methods for creating polymers of high stereoregularity with higher yields than the existing methods, by the use of certain silicone compounds, have been developed by Dow Corning of the U.S. (U.S. Pat. No. 5,175,332 and EP Laid-Open No. 602,922), Mitsui Petrochemical of Japan (Korean Patent Publication Nos. 10-1992-2488 and 10-1993-665; U.S. Pat. No. 4,990,479; EP Laid-Open No. 350,170A; Canadian Pat. No. 1,040,379), Samsung General Chemicals of Korea (Korean Patent Laid-Open No. 10-1998-082629), and other well-known European companies.
SUMMARY OF INVENTION
The objective of the present invention is to provide a method of producing olefin homo- or co-polymers of high stereoregularity with high yields, and the catalyst system used therein, while controlling the molecular weight distribution of olefin homo- or co-polymers, when applied to the production of olefin homo- or copolymers having more than three atoms of carbon.
Another objective of the present invention is to provide a method of producing polypropylene or propylene copolymers which are appropriate for use in production of films having sufficient heat-sealability, transparency, and anti-blocking properties, and which also are appropriate for injection molded products having superior strength, impact-resistance, fluidity and heat-sealability at low temperature.
DETAILED DESCRIPTION OF INVENTION
The method of (co)polymerization of &agr;-olefins using a catalyst system includes the following components:
(1) a solid complex titanium catalyst prepared by means of a production method which includes the following steps:
(a) preparing a magnesium compound solution by dissolving magnesium halide and a compound of Group IIIA of the Periodical Table in a solvent mixture of cyclic ether, one or more types of alcohol, a phosphorus compound, and an organic silane;
(b) precipitating the solid particles by reacting said magnesium compound solution with a transition metal compound, a silicon compound, a tin compound, or mixtures thereof, and
(c) reacting said precipitated solid particles with a titanium compound and electron donors;
(2) an organometallic compound of metal of Group IIIA of the Periodical Table; and
(3) external electron donors containing three or more types of organo-silicon compounds, wherein the MFRs (Melt Flow Rate) of the homopolymers obtained at the time of polymerization using individual organo-silicon compounds under the same polymerization conditions are 5 or less, 5-20, and 20 or higher, respectively.
With respect to the catalyst system used in the method of (co)polymerization of &agr;-olefin of the present invention, the method of producing said solid complex titanium catalyst is a method disclosed in Korean Patent Laid-Open No. 10-2000-009625, the content of which is incorporated herein in toto without specific references.
The solid complex titanium catalyst (1) used in the method of homo- or co-polymerization of &agr;-olefin of the present invention has excellent catalytic activity, as compared with the conventional titanium catalysts, and is capable of producing polymers of high stereoregularity with a broad molecular weight distribution.
In step (a) of the method of producing said solid complex titanium catalyst (1), a magnesium compound may include non-reductive liquid magnesium compounds, for example, such magnesium halides as magnesium chloride, magnesium bromide, magnesium iodide, and magnesium fluoride; such alkoxymagnesium halides as methoxy magnesium chloride, ethoxymagnesium chloride, isopropoxymagnesium chloride, butoxymagnesium chloride, octoxymagnesium chloride; such aryloxymagnesium halides as phenoxymagnesium chloride and methylphenoxymagnesium chloride; such alkoxymagnesiums as ethoxymagnesium, isopropoxymagnesium, butoxymagnesium and octoxymagnesium; such aryloxymagnesiums as phenoxymagnesium and dimethylphenoxymagnesium; and such magnesium salts of carboxylic acid as laurylmagnesium and magnesium stearate. These magnesium compounds may be in the form of complex compounds, or in the form of a mixture with other metals. Moreover, a mixture of two or more magnes

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