Method for producing ethylene homo- and co-polymer

Details Method for producing ethylene homo- and co-polymer Method for producing ethylene homo- and co-polymer

2001-05-25

2004-10-12

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...

C526S128000, C526S125100, C526S124300, C526S142000, C526S348000, C502S115000, C502S120000, C502S125000, C502S126000, C502S127000, C502S103000

Reexamination Certificate

active

06803427

ABSTRACT:

TECHNICAL FIELD
The present invention relates to a method for preparing an ethylene polymer or copolymer, and more particularly a method for producing, by use of a catalyst of high activity, an ethylene polymer or copolymer with high bulk density and a narrow molecular weight distribution.
DESCRIPTION OF THE RELEVANT ART
Magnesium-containing catalysts for production of ethylene polymer or copolymer are known to have very high catalytic activity and endow the produced polymer with a high bulk density. They are also known to be suitable for both liquid and gaseous reactions alike. The liquid polymerization of ethylene means the reaction taking place in the state of bulk ethylene or in a medium like isopentane and hexane, and in terms of the adaptability of a catalyst in such reactions its high activity and the resultant bulk density of a polymer are features of importance. A significant variable decisive of the properties of an ethylene polymer or copolymer, produced with the use of such a catalyst, is the molecular weight distribution. A narrow molecular weight distribution is very advantageous in later manufacture of injection products.
Many catalysts containing magnesium and titanium for production of olefin and the processes for production of these catalysts have been reported. In particular, many processes making use of magnesium solutions to obtain catalysts for polymerization of olefin which has a high bulk density, have been learned. They include processes to obtain magnesium solutions by reacting magnesium compounds with such electron donors as alcohol, cyclic ether, organic carboxyl acid, etc., in the presence of hydrocarbon solvents. Instances where alcohol was used are referred to in U.S. Pat. Nos. 4,330,649 and 5,106,807. Methods for producing a magnesium-carrying catalyst by reacting a magnesium solution with halogen compounds such as titanium tetrachloride are well known. There have also been efforts to control the catalyst's activity and the polymer's molecular weight distribution by addition of ester compounds. These catalysts have a merit in providing the polymer's high bulk density, but their catalytic activity and the polymer's molecular weight distribution have something yet to be improved. Tetrahydrofuran, a cyclic ester, has been used as a magnesium compound solvent in U.S. Pat. Nos. 4,477,639 and 4,518,706.
Meanwhile, U.S. Pat. Nos. 4,847,639, 4,816,433, 4,829,037, 4,970,186, and 5,130,284 have reported use of electron donors such as magnesium alkoxide, dialkylphthalate, phthaloyl chloride, etc., in reaction with a titanium chloride compound for production of catalysts with high catalytic activity and the resultant olefin's improved bulk density.
U.S. Pat. No. 5,459,116 has reported a method for production of a titanium-carrying solid catalyst by reacting a magnesium solution containing an ester having at least one hydroxy group as electron donor with a titanium compound. By this method it is possible to obtain a catalyst which is excellent in catalytic activity, and provides the resultant polymer with high bulk density, but the polymer has something yet to be improved in its molecular weight distribution.
Use of external electron donors in polymerization of &agr;-olefin, especially polypropylene for improvement of stereoregularity, is generally known, and is, commercially, in wide use. As external electron donors, alkoxysilane compounds are widely known, but it is also known that, although the polymer's stereoregularity improves with the use of these, generally the polymer's molecular weight distribution becomes relatively broad. KP 93-665 has shown a way and its merit of rendering the polymer's molecular weight distribution narrower by the use of organic silane as an external electron donor in polymerization of propylene.
SUMMARY OF THE INVENTION
An objective of the present invention is to provide a method and catalyst for production of an ethylene polymer or copolymer with a large bulk density, and a narrow molecular weight distribution; and more particularly, a method and catalyst for producing an ethylene polymer or copolymer of well-regulated granular forms, high polymerization activity, and a narrow molecular weight distribution.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The process of the embodiment described herein for producing an ethylene polymer or copolymer involves preparing a solid titanium complex catalyst in a simple yet effective process using magnesium, titanium, halogen, and an electron donor, by:
i. producing a magnesium compound solution by contact-reacting a halogenated magnesium compound and alcohol,
ii. reacting the said solution with an ester compound containing at least one hydroxy group and a silicon compound containing an alkoxy group, and
iii. adding thereto a mixture of a titanium compound and a silicon compound.
An ethylene polymerization or copolymerization is then performed with a compound of an organic metal of Group 2, 12, or 13 on the periodic table of elements by the use of the aforesaid catalyst in the presence of an alkoxy silane compound.
Examples of halogenated magnesium compounds which may be used in production of the catalyst 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 aryloxymagnesium halides as phenoxymagnesium halide and methylphenoxymagnesium halide, for example. Of the above-named compounds, a mixture of two or more may also be used. These magnesium compounds may also be used effectively when they are 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 for. producing the magnesium compounds. In such cases, they generally may be regarded as mixtures of these listed magnesium compounds. For example, the compounds obtained by reacting a magnesium compound with a polysiloxane compound, a halogen-containing silane compound, or alcohol; or the compounds obtained by reacting a magnesium metal with alcohol, phenol, or ether in the presence of halosilane, phosphor pentachloride, or thionyl chloride may also be used. The preferable magnesium compounds are magnesium halides, especially magnesium chloride; alkylmagnesium chlorides, preferably those that have a C
1
~C
10
alkyl group; alkoxy magnesium chlorides, preferably those that have a C
1
~C
10
alkoxy group; and aryloxy magnesium chlorides, preferably those that have a C
6
~C
20
aryloxy group.
Examples of hydrocarbon solvents which may be used here include, for example: aliphatic hydrocarbons, such as pentane, hexane, heptane, octane, decane or kerosene; alicyclic hydrocarbons such as cyclobenzene, methylcyclobenzene, cyclohexane, or methylcyclohexane; aromatic hydrocarbons such as benzene, toluene, xylene, ethylbenzene, cumen, and cymene; and halogenated hydrocarbons such as dichloropropane, dichloroethylene, trichloroethylene, carbon tetrachloride, and chlorobenzene.
In conversion of the above-listed halogenated magnesium compounds into a magnesium compound solution, alcohol is used in the presence or absence of the above-listed hydrocarbons. The kinds of alcohol include alcohols having 1~20 carbons, such as methanol, ethanol, propanol, butanol, benzene alcohol, phenylethyl alcohol, isopropylenebenzyl alcohol, and cumyl alcohol; and preferably alcohols that have 1~12 carbons. The size of granules of the catalyst and the granular distribution in the resultant polymer vary according to the kinds and total quantity of alcohol, the kinds of magnesium compound, the ratio of magnesium to alcohol, etc.; but the total quantity of alcohol

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