Catalyst formulation and polymerization processes

Details Catalyst formulation and polymerization processes Catalyst formulation and polymerization processes

2000-08-22

2003-12-23

Choi, Ling-Siu (Department: 1713)

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

Polymers from only ethylenic monomers or processes of...

C526S123100, C526S124100, C526S124300, C526S125100, C526S128000, C526S348000, C502S103000, C502S104000, C502S115000, C502S116000

Reexamination Certificate

active

06667380

ABSTRACT:

FIELD OF THE INVENTION
This invention relates to the polymerization of unsaturated hydrocarbons over Ziegler-type catalysts, and more particularly, to processes for formulating such catalysts by sequentially mixing the various components thereof and controlling the orders of addition and the durations of mixing such catalyst components.
BACKGROUND OF THE INVENTION
The polymerization of unsaturated hydrocarbons over Ziegler-type catalysts is well known in the art. Such hydrocarbons normally take the form of short chain alpha olefins such as ethylene, propylene and butylene, including substituted alpha olefins such as substituted vinyl compounds, for example, vinyl chloride or vinyl toluene. However, such unsaturated hydrocarbons can also include di-olefins such as 1-3-butadiene or 1-4-hexadiene or acetylenically unsaturated compounds such as methylacetylene or 2-butyne.
Ziegler-type catalysts incorporate a transition metal, usually titanium, zirconium or hafnium, although other transition metals found in Groups 4, 5 and 6 of the Periodic Table of Elements may be employed, which function to provide sites for the insertion of monomer units into growing polymer chains. One type of such polymerization catalysts are the so-called homogeneous catalyst systems in which the transition metal compound is a metallocene comprising one or more substituted or unsubstituted cyclopentadienyl groups coordinated with the transition metal atom forming the situs for polymer growth. Such metallocene-based catalyst systems are the subject of European Patent Application EP 129,368 and U.S. Pat. Nos. 4,794,096 to Ewen and 4,892,851 to Ewen et al., the latter two patents disclosing catalysts useful in the polymerization of propylene to form isotactic or syndiotactic polypropylene.
The more widely used transition metal catalysts are the so-called heterogeneous catalyst systems in which a transition metal halide, usually zirconium, hafnium or titanium, di-, tri-, or tetra-halides, are incorporated with a support structure, principally based upon magnesium or zinc halides, ethoxides or the like. For example, U.S. Pat. No. 4,476,289 to Mayr et al. discloses so-called “activated” titanium tetrahalides, more specifically, titanium tetrachloride, supported on anhydrous magnesium or zinc halides, principally magnesium chloride or magnesium bromide. The transition metal component is used in conjunction with a second component, commonly referred to as a co-catalyst, which as described in the Mayr et al. patent, is a hydride or organometallic compound based primarily upon aluminum, although lithium or magnesium based compounds are also disclosed. A supported catalyst containing yet another component is disclosed in U.S. Pat. No. 4,636,486 to Mayr et al. Here, the titanium compound, which may be a halide, an oxyhalide or an alcoholate in either the di-, tri- or tetra-valent form, is composited with the magnesium support, together with an electron donor compound. Such electron donors, commonly referred to as internal electron donors because they are incorporated as part of the transition metal catalyst component, can be selected from a broad class of compounds including amines, amides, phosphines, ethers, thioethers, alcohol esters, aldehydes, and ketones. As in the case of the aforementioned U.S. Pat. No. 4,476,289 to Mayr, the catalyst system here also includes an organoaluminum co-catalyst such as triethylaluminum, commonly referred to as TEAL. Both of the Mayr et al. patents teach that the molar ratio of the organoaluminum compound and the titanium catalyst component is not critical. In the polymerization of ethylene, such ratio is said to preferably be between 50 and 1,000.
Yet a third component often employed in Ziegler-type catalyst systems is a so-called external electron donor. The external electron donors function similarly as the internal electron donors and in a complimentary or supplementary manner to regulate monomer insertion into the polymer chain growing on the transition metal active sites. Thus, the electron donors can have an impact upon catalyst activity, polymer molecular weight, and polymer morphology as reflected in stereospecificity and physical parameters such as melting point. For example, in the polymerization of propylene, the addition of electron donors under controlled conditions can result in dramatic increases in activity (the amount of polymer produced per unit of catalyst) and in stereoregularity, e.g., an increase in isotactic polymer with a corresponding decrease in atactic. The most widely used external electron donors are organosilicon compounds such as organosilanes and organosiloxanes, including silyl ethers and esters such as alkyl or arylalkyl alkoxysilanes.
The complimentary nature of the internal and external electron donors is addressed in Soga, K. et al., “Effect of Diesters and Organosilicon Compounds on the Stability and Stereospecificity of Ziegler-Natta Catalysts”,
Transition Metal Catalyzed Polymerizations: Ziegler
-
Natta and Metathesis Polymerizations
, Quirk, R. P., Ed., Cambridge University Press, New York, 1988, pp. 266-279. As discussed in Soga, the concentrations of the internal and external donors in the catalyst system can be adjusted in order to optimize the activity and the stereospecificity of the catalyst. In the experimental work reported there, the transition metal catalyst component comprising titanium tetrachloride supported on magnesium dichloride with an internal donor, e.g., di-N butylphthalate, was slurried in hexane followed by the addition of an external electron donor, phenyl tri-ethoxysilane, and triethylaluminum (TEA) co-catalyst. Soga et al. report on polymerization rates over periods of several hours and isotactic indices measured over periods of several hours for various internal, external catalyst systems using several kinds of organosilicon compounds at varying concentrations expressed in terms of silicon titanium mole ratios and TEA/titanium mole ratios. Among the various electron donors used in the Soga et al. experimental work, diphenyldimethoxysilane appeared to have the most efficiency in terms of improving activity and/or stereospecificity of the catalyst system, followed by phenyltriethoxysilane, followed in turn by phenyltrimethoxysilane. Various other organosilicon compounds were generally less efficient, although still effective. The aluminum/titanium mole ratios employed in Soga range from about 50 to 200; the silicon/titanium mole ratios range from about 10 to 50.
U.S. Pat. No. 4,287,328 to Kikuta et al., is directed to the polymerization of alpha olefins in the presence of multi-component catalyst systems involving a “solid product” combined with an organoaluminum compound including, for example, C
1
-C
10
trialkylaluminum, triethylaluminum, alkyl alkyoxyaluminums, and alkylaluminum halides, and an electron donor including various brganic acids, alcohols, ethers, aldehydes, ketones, amines, alkenol amines, esters, phosphines, phosphites, thioethers, thioalcohols, silanes, and siloxanes. The “solid product” catalyst component is formed by reacting a trivalent metal halide such as aluminum trichloride, aluminum tribromide or ferric trichloride with a divalent metal compound such as magnesium, calcium, or zinc hydroxide or oxide or carbonate with titanium tetrachloride, characterized as an electron acceptor. Numerous orders of additions of the various components are described in Kikuta et al., especially in columns 6 through 9. Conditions of mixing can vary over wide temperature ranges and time intervals, but temperatures are preferably in the range of room temperature to about 100° C. The mixing of the various components can be carried out over periods of several minutes to several hours.
U.S. Pat. No. 4,567,155 to Tovrog et al., discloses multi-component catalyst systems useful in the gas phase polymerization of alpha olefins. In Tovrog et al., the catalyst systems comprise two base catalyst components, each containing subcomponents. The first component, identified as component “A” comprises a titanium component suppor

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