JPH05194636A - Polymerization of alpha-olefin - Google Patents

Abstract

PURPOSE:To polymerize an alpha-olefin into a polymer having a wide mol. wt. distribution and excellent stereoregularity by employing a catalyst comprising a solid catalyst component such as a magnesium halide and an organic metal compound in the presence of a specific chelate compound and an electron donating compound. CONSTITUTION:An alpha-olefin such as propylene is polymerized in the presence of a catalyst comprising an organic metal compound such as triethylaluminum and a solid catalyst component obtained by carrying a titanium halide such as titanium tetrachloride on a magnesium halide such as magnesium chloride, a chelate compound of one or more group VIII transition metals (e.g. iron, ruthenium) and one or more electron-donating compounds such as an alkoxysilane. The titanium compound and the transition metal chelate compound are preferably used in a molar ratio of 1/1 to 0.0001/1.

Description

Description: FIELD OF THE INVENTION The present invention relates to a method for polymerizing α-olefins. More specifically, it relates to a method for producing a highly stereoregular poly α-olefin having a wide molecular weight distribution by combining specific compounds. It has been widely practiced to polymerize olefins using a catalyst composed of a transition metal compound and an organometallic compound to produce a polyolefin, but polyolefins having various molecular weight distributions can be produced depending on the application field of the polyolefin. Since they are required, they are usually manufactured by using different catalysts. The relationship between the catalyst and the molecular weight distribution of the obtained polyolefin is not clear, and it is usual to synthesize the catalyst by trial and error and polymerize it to obtain a catalyst giving a desired molecular weight distribution. A variety of catalyst systems are known to provide a wide molecular weight distribution. However, since the above catalyst systems differ in the reagents used, the manufacturing method, the utilization method, etc., depending on the respective catalyst systems, it is possible to use polyolefins having different molecular weight distributions in the same polymerization system as catalysts. It is extremely difficult to produce it by changing it, and particularly in the polymerization of α-olefin such as propylene, it is extremely difficult to change only the molecular weight distribution because the stereoregularity of the polymer obtained by the catalyst is different. The present inventors have conducted intensive studies on a method for solving the above problems and producing a polymer having a wide molecular weight distribution, and completed the present invention. That is, the present invention is a method for polymerizing an α-olefin using a catalyst composed of a solid catalyst component obtained by supporting titanium halide on magnesium halide and an organometallic compound, wherein at least 1 is used in the polymerization. A method for polymerizing an α-olefin, which comprises polymerizing an α-olefin in the presence of one chelate compound of a Group VIII transition metal of the periodic table and at least one electron-donating compound. In the present invention, as the solid catalyst component obtained by supporting titanium halide on magnesium halide, various electron donating compounds such as ether, ester, alkoxysilane, amine, amide, etc. are used in combination at the time of supporting. It is particularly preferable to use a solid catalyst component in which titanium tetrachloride and an aromatic diester are supported on magnesium halide, because a narrow molecular weight distribution to a wide molecular weight distribution can be produced depending on the conditions. In the present invention, as the magnesium halide used for producing the solid catalyst component, substantially anhydrous magnesium halide can be used, and one containing water of usually several% or less can also be used. As the magnesium halide, magnesium chloride, magnesium bromide, a complex thereof with an ether or a monoester, or a eutectic of magnesium chloride and magnesium bromide can be used. As the phthalic acid diester suitable as an aromatic diester, an ester of phthalic acid and an alcohol having 1 to 12 carbon atoms can be preferably used, and dimethyl phthalate, diethyl phthalate, dipropyl phthalate, dibutyl phthalate can be used. , Dioctyl phthalate, didecyl phthalate,
Diphenyl phthalate, dibenzyl phthalate, diphthalate
In addition to -2-ethylhexyl and the like, diesters such as butylbenzyl phthalate and ethylhexyl phthalate having different alcohols forming two ester bonds can also be used. As the tetravalent titanium halide preferably used in the present invention, chlorine can be preferably exemplified as the halogen, and one in which a part of the halogen is changed to an alkoxy group can be used, but the tetravalent titanium is particularly preferable. Titanium chloride is used. Here, the titanium halide compound can also be used by forming a complex with a diester of phthalic acid in advance. In the present invention, it is necessary to use an electron donating compound as a stereoregularity improving agent in the polymerization. Here, as the electron donating compound, alkoxysilane or substituted piperidine is preferably used as a stereoregularity improving agent. As the alkoxysilane, an organic silane compound containing 1 to 4 alkoxy groups is preferably used,
Examples of the alkoxy group include those having a structure in which oxygen is bonded to a branched or straight chain alkyl group or alkenyl group having 1 to 12 carbon atoms, and the remaining groups are branched or straight chain alkyl group having 1 to 12 carbon atoms. , Or an alkenyl group can be exemplified. As the substituted piperidine, a compound in which part or all of the hydrogens at the 1- and 6-positions are substituted with an alkyl group having 1 to 12 carbon atoms or an alkenyl group can be preferably exemplified. At least one of these electron-donating compounds is used, and if necessary, two or more thereof are mixed and used. Examples of the chelate compound of the transition metal of Group VIII of the Periodic Table used in the present invention include chelate compounds of iron, ruthenium, osmium, cobalt, rhodium, iridium, nickel, palladium and platinum. As these ligands, preferably ethylenediamine, 1,3-propadiene, 2,4-pentanediamine, 2,2'-
Bipiperidine, N, N'-dimethyl-1,2-cyclohexanediamine, 4,6-dimethyl-1,9-diamino-3,7-diazanonan, N, N'-bis (2-pyrrolidinemethyl) -1,3 -Alkylpolyamines such as propanediamine, acetylacetone, 1,3-diketones such as dipivaloylmethane, oximes such as dimethylglyoxime, 2-pyridylaldoxime, cytylaldoxime, o-phenylenebis (dimethyl) Phosphines such as phosphine), cyclic polyamines such as 1,4,7,10,13,16-hexaazacyclooctadecane, porphyrins such as octaethylphosphine and tetraphenylporphine, phthalocyanines, boranes and carboranes Among these, transition metal chelate compounds in which ligands such as acetylacetone and 1,3-diketones such as dipivaloylmethane are coordinated are particularly preferable. You can These transition metal chelate compounds may be used either individually or in combination of two or more, and are added to the polymerization system together with the above-mentioned solid catalyst component, electron donor compound and the organometallic compound described below during polymerization. It is preferable to use the metal chelate compound after the contact treatment with the organoaluminum compound in advance. In some cases, it may be used by being present in the solid catalyst component. As a solvent for dissolving the transition metal chelate compound, an aromatic hydrocarbon compound having 1 to 20 carbon atoms or a halogenated hydrocarbon compound, specifically, benzene, toluene, ethylbenzene, xylene, cumene, cymene,
Alternatively, those obtained by substituting a part of hydrogen with a halogen element, methylene dichloride, chloroform, ethylene dichloride, trichloroethane and the like can be exemplified. The ratio of the transition metal chelate compound to the titanium compound in the solid catalyst component used in the polymerization is 1: 1 to
A molar ratio of 0.0001: 1 is preferable, and a molar ratio of 0.0001 or less has almost no effect on broadening the molecular weight distribution. Here, the solid catalyst component is an organometallic catalyst component,
If necessary, it can be used after being treated with a small amount of olefin in the presence of the electron-donating compound. The solid catalyst component is preferably used at a slurry concentration of 0.1 to 500 g / liter and a transition metal chelate compound concentration of 0.001 to 100 g / liter. It is preferable to add the solution of the transition metal chelate compound to the slurry of the solid catalyst component while stirring. The preferred solid catalyst component is prepared as follows. The use ratio of the diester of phthalic acid and the titanium halide in the co-milling is 0.3: 1 to 1: 0.3, and more preferably 0.5: 1 to 1: 0.5. If it exceeds this range, the activity and stereoregularity of the polymer obtained when polymerized using the catalyst are insufficient. The ratio of titanium halide to magnesium halide is preferably about 1: 0.001 to 1: 0.5 by weight. When a chelate compound of a Group VIII transition metal of the Periodic Table is added by co-grinding, the molar ratio with the titanium halide is 1: 1 to 0.0001: 1 as described above. Preferably, when it is 0.0001 or less, there is almost no effect of broadening the molecular weight distribution. If necessary, the co-pulverized product is further used as a hydrocarbon compound having 1 to 12 carbon atoms or 1 of its hydrogen.
~ A compound entirely substituted with chlorine, bromine or iodine is preferably heat-treated at 50 ° C to 150 ° C. Upon co-milling, it is possible to further add a carrier inert to the catalyst system. In addition to inorganic substances such as silica and alumina, polyethylene, polypropylene,
Polymer compounds such as polystyrene can be used. In the present invention, the organometallic compound is
Preferably, an organoaluminum compound can be used, and more preferably, a trialkylaluminum such as trimethylaluminum, triethylaluminum, tripropylaluminum, and tributylaluminum, and an alkylaluminum having one or two hydrocarbon residues substituted with chlorine or bromine. Halogen is exemplified. The use ratio of the organometallic compound and the alkylalkoxysilane to titanium in the solid catalyst component is 1: 1: 1 to 1: 10000: 10000 molar ratio, usually 1: 1: 1 to 1: 1.
It is a 1000: 1000 molar ratio. In the present invention, the transition metal chelate compound is used by adding it to the polymerization system together with the above catalyst. At this time, the transition metal chelate compound may be added at the same time as the initiation of the polymerization, or may be added after a specific amount of the polymerization, and further when the polymerization is carried out by using a reactor in which two or more polymerization tanks are connected. It is also possible to add it only to the polymerization tank, or to change the addition amount. The amount added is generally the same as that used in the above-mentioned method of introducing the solid catalyst, or generally about 2 to 10 times. In the present invention, as the α-olefin,
It means a mixture of one or more α-olefins having 3 to 12 carbon atoms, or a mixture with a small amount of ethylene,
Examples of α-olefins include propylene, butene-1, pentene-1, hexene-1, heptene-1, octene-1, 4-methylpentene-1. In the present invention, the method for polymerizing the α-olefin is not particularly limited, and various known methods can be adopted.
Any of a solvent polymerization method using an inert hydrocarbon as a medium, a bulk polymerization method using a liquid α-olefin as a medium, and a gas phase polymerization method in which a liquid medium is substantially absent can be adopted. In the polymerization, the temperature is usually from room temperature to 150 ° C., and the pressure is from normal pressure to 100 kg / cm ² , and in addition to the homopolymerization of α-olefin, it is carried out in a random or block copolymer with each other or with ethylene. The present polymerization method can be preferably adopted for the polymerization, and a block copolymer having excellent physical properties can be provided by adding the transition metal chelate compound only to the copolymerization portion. Further, it is possible to continuously polymerize by connecting two or more reaction tanks, and at that time, it is also possible to produce a polymer having a wider molecular weight distribution by changing the hydrogen concentration in each tank.
Further, it is possible to give a polyolefin with high activity per solid catalyst even under a condition of relatively low hydrogen concentration. In the catalyst system of the present invention, it is easy to lower the hydrogen concentration in the subsequent polymerization tank, and a polymer having a higher molecular weight can be produced in the subsequent reaction tank. Although the reason is not clear, in the present invention,
It is possible to lower the hydrogen concentration sufficiently without purging hydrogen from the polymerization tank in the latter stage, and by purging a large amount of hydrogen in the latter polymerization tank with the conventional catalyst system, the polymer obtained in each tank Even if there is a large difference in molecular weight as compared with the method of making a difference in molecular weight, no spots are found on the surface of the molded product. Therefore, when the method of the present invention is used, it is easy to lower the hydrogen concentration in the reaction tank at the subsequent stage, and by adopting such a method, a polymer having a wider molecular weight distribution can be obtained. .. The present invention will be further described with reference to the following examples. Example 1 A vibrating mill equipped with four grinding pots having an inner volume of 4 liter and containing 9 kg of steel balls having a diameter of 12 mm was prepared. Magnesium chloride (300 g), diisobutyl phthalate (75 ml) and titanium tetrachloride (60 ml) were added to each pot in a nitrogen atmosphere and pulverized for 40 hours. 10 g of the above co-ground product was placed in a 200 ml flask, 60 ml of toluene was added, the mixture was stirred at 114 ° C. for 30 minutes, and then allowed to stand to remove the supernatant. Then n-heptane 100 ml
The solid content was washed 3 times at 20 ° C. and dispersed in 100 ml of n-heptane to obtain a transition metal catalyst component slurry. The resulting transition metal catalyst component contained 1.9 wt% titanium and 14.2 wt% diisobutyl phthalate. A fully dried autoclave having an internal volume of 5 liters, which had been purged with nitrogen, was prepared, and triisobutylaluminum 0.174 ml diluted with heptane, cyclohexylmethyldimethoxysilane 0.01 ml, and the above transition metal catalyst component were prepared.
15 mg and 0.5 mg of nickel acetylacetonate which had been previously treated with triethylaluminum were added, 1.5 kg of propylene and 1.63 Nl of hydrogen were added, and polymerization was carried out at 70 ° C. for 2 hours. After the polymerization, unreacted propylene was purged, dried at 80 ° C. for 8 hours, and weighed to obtain 452 g of polypropylene. The intrinsic viscosity (hereinafter abbreviated as η) measured with a 135 ° C. tetralin solution of polypropylene is 1.94, and the boiling n-heptane extraction residual ratio (weight of unextracted polymer / weight of unextracted polymer) measured with a Soxhlet extractor. Displayed as a percentage, abbreviated as II below is 97.4%, and the ratio of the weight average molecular weight and the number average molecular weight measured by gel permeation chromatography at 135 ° C using 1,2,4-trichlorobenzene as a solvent (hereinafter MW / (Abbreviated as MN) was 6.0. Comparative Example 1 Polymer 583 g was obtained in the same manner as in Example 1 except that nickel acetylacetonate was not used in the polymerization. The η of this powder is 1.64, II is 97.9%, and MW / MN is 5.
It was 0. Example 2 555 g of powder was obtained in the same manner as in Example 1 except that the amount of nickel acetylacetonate used was changed to 0.2 mg. The η of this powder is 1.70, II is 97.3%, and MW / MN is 5.
Was eight. Example 3 568 g of powder was obtained in the same manner as in Example 1 except that the amount of nickel acetylacetonate used was changed to 3 mg. The η of this powder is 2.94, II is 98.4%, and MW / MN is 6.
It was 9. Industrial Applicability By carrying out the method of the present invention, highly stereoregular poly-α-olefins having a relatively wide molecular weight distribution can be produced, which is industrially valuable.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a flow chart diagram for helping understanding of the present invention.

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[Procedure amendment] [Date of submission] January 23, 1992 [Procedure Amendment 1] [Document name for amendment] Specification [Item name for amendment] 0013 [Correction method] Change [Content of amendment] [0013] The present invention Examples of the chelate compound of Group VIII transition metal of the periodic table used in (1) include chelate compounds of iron, ruthenium, osmium, cobalt, rhodium, iridium, nickel, palladium, platinum, and the like. As these ligands, preferably ethylenediamine, 1,3-propanediamine, 2,4-pentanediamine, 2,
2'-bipiperidine, N, N'-dimethyl-1,2-cyclohexanediamine, 4,6-dimethyl-1,9-diamino-3,7-diazanonane, N, N'-bis (2-pyrrolidinemethyl)- Alkyl polyamines such as 1,3-propanediamine, 1,3-diketones such as acetylacetone and dipivaloylmethane, oximes such as dimethylglyoxime, 2-pyridylaldoxime, salicylaldoxime, o-phenylenebis Phosphines such as (dimethylphosphine), cyclic polyamines such as 1,4,7,10,13,16-hexaazacyclooctadecane, porphyrins such as octaethylporphine and tetraphenylporphine, phthalocyanines, boranes and carboranes And the like. Among them, particularly preferable are transition metal chelate compounds in which ligands such as acetylacetone and 1,3-diketones such as dipivaloylmethane are coordinated. And the like.

Claims (1)

Claim: What is claimed is: 1. A method for polymerizing an α-olefin using a catalyst comprising a solid catalyst component obtained by supporting titanium halide on magnesium halide and an organometallic compound. A method for polymerizing an α-olefin, which comprises polymerizing an α-olefin in the presence of a chelate compound of at least one Group VIII transition metal of the periodic table and at least one electron-donating compound.