JPH05287018A - Method for polymerizing α-olefin - Google Patents

Abstract

(57) [Summary] [Structure] A method for polymerizing an α-olefin using a catalyst comprising a solid catalyst component obtained by supporting a titanium halide on a magnesium halide and an organometallic compound. The α-olefin is polymerized in the presence of a cyclopentadiene compound of Group 3, Group 5, Group 5, Group 12 or Group 13 metal and an electron donating compound. [Effect] A highly stereoregular polyolefin having a relatively wide molecular weight distribution can be produced.

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 comprising a solid catalyst component obtained by supporting a titanium halide on a magnesium halide and an organometallic compound. Table 2nd group, 3rd
An α-olefin characterized by polymerizing an α-olefin in the presence of a cyclopentadiene compound of at least one metal selected from Group 5, 5, 12, or 13 and at least one electron-donating compound. Is a polymerization method of. 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. The cyclopentadiene compound of a metal of Group 2, Group 3, Group 5, Group 12 or Group 13 of the periodic table (hereinafter abbreviated as a metal cyclopentadiene compound) used in the present invention is as follows. Examples thereof include cyclopentadiene compounds such as beryllium, magnesium, calcium, scandium, yttrium, lanthanum metal, zinc, cadmium, mercury, boron, aluminum and gallium. These cyclopentadiene ligands are preferably cyclopentadiene, methylcyclopentadiene, dimethylcyclopentadiene, trimethylcyclopentadiene, tetramethylcyclopentadiene, pentamethylcyclopentadiene, ethylcyclopentadiene, diethylcyclopentadiene, triethylcyclopentadiene, tetraethylcyclopentadiene. Pentadiene, pentaethylcyclopentadiene, indene, anthracene,
Examples include ligands such as fluorene, methylindene, dimethylindene, propylindene, dipropylindene, trimethylindene, tetramethylindene, methylanthracene, dimethylanthracene, and tetramethylanthracene. These metal cyclopentadiene compounds may be used either individually or in combination of two or more, and are used by adding them to the polymerization system together with the solid catalyst component, the electron donor compound and the organic metal compound described later during the polymerization. Examples of the solvent for dissolving the metal cyclopentadiene compound include ether compounds such as diethyl ether, dibutyl ether, tetrahydrofuran, tetrahydropyran, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, dioxane, ester compounds and amine compounds. Further, the same effect can be obtained even if the metal cyclopentadiene compound is added in the form of powder or slurry. When used in a slurry state, it is used by being dispersed in a hydrocarbon solvent or a liquid monomer. The ratio of the metal cyclopentadiene compound to the titanium compound in the solid catalyst component used in the polymerization is
A molar ratio of 1: 1 to 1: 0.0001 is preferable, and if it is 0.0001 or less, there is almost no effect of 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 metal cyclopentadiene compound concentration of 0.001 to 100 g / liter. When adding the solution of the metal cyclopentadiene compound to the slurry of the solid catalyst component, it is preferable to carry out the 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. If necessary, the co-pulverized product is a hydrocarbon compound having 1 to 12 carbon atoms or one of the hydrogen compounds.
~ A compound entirely substituted with chlorine, bromine or iodine, which is preferably heat-treated at 50 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 metal cyclopentadiene compound is used by adding it to the polymerization system together with the above catalyst. At this time, the metal cyclopentadiene 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 performed by using a reactor having two or more polymerization tanks connected. It is also possible to add it only to the polymerization tank, or to change the addition amount. 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 metal cyclopentadiene compound only to the copolymerization portion. Further, it is also possible to connect two or more reaction tanks for continuous polymerization, and at that time, it is also possible to produce a polymer having a broader 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. Although the reason is not clear, in the present invention, the hydrogen concentration can be sufficiently lowered without purging hydrogen from the polymerization tank in the latter stage, and the conventional catalyst system can be used in the latter polymerization tank. Even if the difference in the molecular weight of the polymer obtained in each tank is large by purging a large amount of hydrogen in step 1, even if the difference in the molecular weight is large, the surface of the molded product does not have any spots. Therefore, when the method of the present invention is used, it is easy to lower the hydrogen concentration in the subsequent reaction tank, 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 vibration mill equipped with four grinding pots having an inner volume of 4 liters 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 co-ground product was placed in a 200 ml flask, 60 ml of toluene was added, and the mixture was stirred at 114 ° C. for 30 minutes and then left 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 solid catalyst component slurry. The resulting solid catalyst component contained 1.9 wt% titanium and 14.2 wt% diisobutyl phthalate. A fully dried and nitrogen-substituted autoclave having an internal volume of 5 liters was prepared, and 0.20 ml of triethylaluminum diluted with heptane, 0.01 ml of cyclohexylmethyldimethoxysilane, 15 mg of the above solid catalyst component, and 0.35 of magnesium dicyclopentadienide. 1.5 mg of propylene and 3.90 Nl of hydrogen were added, and the mixture was polymerized at 70 ° C for 2 hours.
After the polymerization, unreacted propylene was purged, dried at 80 ° C. for 8 hours, and weighed to obtain 420 g of polypropylene. Also, the intrinsic viscosity (hereinafter abbreviated as η) measured with a 135 ° C. tetralin solution of polypropylene is 2.60, and the boiling n-heptane extraction residual rate (weight of extraction residual polymer / weight of polymer before extraction) measured with a Soxhlet extractor. Is expressed as a percentage, hereinafter abbreviated as II) is 97.7%, and the ratio of the weight average molecular weight to the number average molecular weight measured by gel permeation chromatography using 135 ° C 1,2,4-trichlorobenzene as a solvent (hereinafter , MW / MN) was 7.8. Comparative Example 1 Polymer 583 was prepared in the same manner as in Example 1 except that magnesium dicyclopentadienide was not used in the polymerization.
got g. Η of this polymer is 1.64, II is 97.9%, MW / M
N was 5.0. Example 2 In the same manner as in Example 1 except that mercury cyclopentadienide was used instead of magnesium dicyclopentadienide, 430 g of a polymer was obtained. Η of this polymer is 2.7
2, II was 96.4% and MW / MN was 7.6. Example 3 483 g of a polymer was obtained in the same manner as in Example 1 except that diethylaluminum cyclopentadienide was used in place of magnesium dicyclopentadienide. The η of this polymer was 1.86, II was 97.6%, and MW / MN was 7.2. Industrial Applicability By carrying out the method of the present invention, highly stereoregular poly-α-olefin 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.

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. Periodic Table 2nd, 3rd, 5th, 1st
A method for polymerizing an α-olefin, which comprises polymerizing an α-olefin in the presence of a cyclopentadiene compound of at least one metal selected from Group 2 or Group 13 and at least one electron-donating compound.