Catalyst for homo- or co-polymerization of ethylene

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

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C502S121000

Reexamination Certificate

active

06803338

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to a catalyst for homo- or co-polymerization of ethylene, or more particularly to a solid titanium catalyst supported on a magnesium-containing carrier, having high catalytic activity and excellent polymerization properties, which can provide polymers of high bulk density and reduce the amount of polymers soluble in a medium during polymerization.
DESCRIPTION OF THE RELEVANT ART
Magnesium-containing catalysts for preparation of an ethylene polymer or copolymer are known to have a high catalytic activity and to be instrumental in production of polymers having a high bulk density. They are also known to be suitable for both liquid and gaseous phase polymerization alike. By the liquid phase ethylene polymerization is meant the polymerization reaction performed of bulk ethylene or in such media as isopentane and hexane, while the features important for the catalyst used in such polymerizations are high catalytic activity, the resultant polymer's high bulk density, etc. Apart from these, a salient variable to decide the quality of a catalyst, especially its commercial usefulness, is how much polymer remains soluble in the medium.
Many catalysts based on magnesium titanium along with the processes of their production have been reported. Uses of a magnesium solution intended to obtain a catalyst for polymerization of olefin having a high bulk density have also been learned. There are ways of obtaining magnesium solutions by means of reacting magnesium compounds with such electron donors as alcohol, amine, cyclic ether, organic carboxylic acid, etc, in the presence of hydrocarbon solvents. Of which, instances of using alcohol are disclosed in U.S. Pat. Nos. 4,330,649 and 5,106,807. A way of preparation of a magnesium-carrying catalyst by reacting a magnesium solution with such a halogen-containing compound as titanium tetrachloride is also well known. Attempts have been made by addition thereto of ester compounds to adjust the catalytic activity and the resultant polymer's molecular weight distribution. Such catalysts provide high bulk density of polymer, but have much yet to be improved in the aspects of the catalytic activity and the produced polymer's molecular weight distribution. Tetrahydrofuran, a cyclic ether, is in use as solvent for magnesium compounds in U.S. Pat. Nos. 4,777,639 and 4,518,706.
U.S. Pat. Nos. 4,847,227, 4,816,433, 4,829,037, 4,970,186, and 5,130,284 have disclosed processes for producing catalysts of excellent activity for polymerization of olefin having a high bulk density by reacting titanium chlorides with such electron donors as magnesium alkoxide, dialkyl phthalate, phthaloyl chloride, etc.
U.S. Pat. No. 5,459,116 has reported a process for preparation of a titanium-carrying solid catalyst by contact-reacting a magnesium solution containing, as electron donor, an ester having at least one hydroxy group with a titanium compound. Such processes make it possible to obtain a catalyst with a high catalytic activity, ensuring the produced polymer a high bulk density, but co-polymerization aspects have not been paid due heed.
SUMMARY OF THE INVENTION
As can be seen from the above, It is desirable that catalysts be developed for homo-and co-polymerization of ethylene that are simple in their production processes, yet have a high catalytic activity, and provide the produced polymers with a high bulk density, and give reduced soluble polymer left behind in the medium in slurry polymerization.
Hence the present invention, wherein it has been made possible to produce a catalyst of high activity from low-priced materials by means of a simple industrial process, the said catalyst being instrumental in preparation of polymers having a high bulk density and with less polymeric constituents soluble in the medium after the reaction. The actual steps and processes for production of the catalyst revealed in the present embodiment have never before been known in any existing patents or literature.
The present embodiment provides a solid catalyst of high catalytic activity for homo- and co-polymerization of ethylene, ensuring the polymer produced by the use of the catalyst with a high bulk density and excellent polymerization activity as well as reduced polymeric material to remain soluble in the medium.
The present embodiment also provides a method, simple yet practical, for producing the said solid catalyst.
The solid titanium catalyst, described herein, for homo- and co-polymerization of ethylene, excellent in catalytic activity and instrumental in production of polymers with a high bulk density and less polymer soluble in the medium, is produced by a simple yet effective process comprising Step (i) of producing a magnesium solution by contact-reacting a halogenated magnesium compound and alcohol, Step (ii) of reacting the solution with a phosphorus compound and an ester compound having at least one hydroxy group, and Step (iii) of adding thereto a mixture of a titanium compound and a silicon compound.
The kinds of halogenated magnesium compounds usable include such dihalogenated magnesiums as magnesium chloride, magnesium iodide, magnesium fluoride, and magnesium bromide; such alkylmagnesium halides as methylmagnesium halide, ethylmagnesium halide, propylmagnesium halide, butylmagnesium halide, isobutylmagnesium halide, hexylmagnesium halide, and amylmagnesium halide; such alkoxymagnesium halides as methoxymagnesium halide, ethoxymagnesium halide, isopropoxymagnesium halide, butoxymagnseium halide, and octoxymagnesium halide; and such an aryloxymagnesium halide as phenoxymagnesium halide or methylphenoxymagnesium halide. A mixture of two or more of these compounds can also be used. These magnesium compounds may be effective when they are used in the form of a complex with other metals.
The above-listed halogenated magnesium compounds may be represented by simple chemical formulae, but exceptions may arise from differences in the methods of their production. In such exceptional cases they generally can be regarded as mixtures of these listed magnesium compounds. For instance, the compounds obtained by reacting a magnesium compound with a polysiloxane compound, a halogen-containing silane compound, ester, or alcohol; the compounds obtained by reacting a magnesium metal with alcohol, phenol, or ether in the presence of halosilane, phosphorus pentachloride, or thionyl chloride may also be used. The preferable magnesium compounds are magnesium halides, especially magnesium chloride and alkylmagnesium chloride, preferably those that have C
1
~C
10
alkyl groups; alkoxymagnesium chlorides, preferably those that have C
1
~C
10
alkoxy groups; and aryloxy magnesium chlorides and preferably those that have C
6
~C
20
aryloxy groups.
The magnesium solution may be produced with the aforesaid magnesium compounds by the use of an alcohol solvent in the presence or absence of a hydrocarbon solvent.
The kinds of hydrocarbon solvents which may be used for this purpose include, for instance, such aliphatic hydrocarbons as pentane, hexane, heptane, octane, decane, and kerosene; such alicyclic hydrocarbons as cyclobenzene, methylcyclobenzene, cyclohexane, and methylcyclohexane; such aromatic hydrocarbons as benzene, toluene, xylene, ethylbenzene, cumene, and cymene; and such halogenated hydrocarbons as dichloropropane, dichloroethylene, trichloroethylene, carbon tetrachloride, and chlorobenzene.
When a magnesium compound is turned into a solution, alcohol is used in the presence of any of the above-listed hydrocarbons. The kinds of alcohols used for this purpose include, for instance, such an alcohol, which contains from 1~20 carbons as methanol, ethanol, propanol, butanol, pentanol, hexanol, octanol, decanol, dodecanol, octadecylalcohol, benzylalcohol, phenylethylalcohol, isopropylbenzylalcohol, and cumyl alcohol. Of these, the preferable is such an alcohol which contains 1~12 carbons. The desired average size and distribution of particles of the catalyst may vary according to the kinds and total quantity of alcohol, the k

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