JPH04222804A - Polymerization of alpha-olefin - Google Patents

Abstract

PURPOSE:To obtain a highly stereoregular polymer with broad molecular weight distribution by polymerizing an alpha-olefin using a catalyst comprising an organometallic compound and a solid with a Ti halide carried on a Mg halide in the presence of a specific Si compound and an aromatic compound- coordinated Ti compound etc. CONSTITUTION:The objective polymer can be obtained by polymerizing (A) an alpha-olefin (e.g. propylene) using (B) a catalyst comprising (1) a solid catalyst with a titanium halide (e.g. titanium tetrachloride) carried on a magnesium halide (e.g. magnesium chloride) and (2) an organometallic compound (e.g. triethylaluminum) in the presence of (C) at least one branched alkylalkoxysilane compound (e.g. diisopropyldimethoxysilane) and (D) a component such as titanium, zirconium or hafnium compound with at least one aromatic compound as ligand (e.g. dicyclopentadienyltitanium dichloride).

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for polymerizing α-olefins. Specifically, the present invention relates to a method for producing a poly-α-olefin with a wide molecular weight distribution and high stereoregularity by combining specific compounds.

0002

[Prior Art] It is widely practiced to produce polyolefins by polymerizing olefins using catalysts consisting of transition metal compounds and organometallic compounds, but polyolefins with various molecular weight distributions are required depending on the field of use of polyolefins. Therefore, they are usually produced by using different catalysts.

The relationship between the catalyst and the molecular weight distribution of the obtained polyolefin is not clear, and catalysts are usually synthesized by trial and error and then polymerized to obtain a catalyst that gives the desired molecular weight distribution, ranging from narrow to wide. Various catalyst systems that provide molecular weight distribution are known.

0004

[Problems to be Solved by the Invention] However, since the reagents used, production methods, and utilization methods differ depending on the catalyst system, it is difficult to produce polyolefins with different molecular weight distributions using the same polymerization system by changing the catalyst. In particular, in the polymerization of α-olefins such as propylene, the stereoregularity of the polymer obtained differs depending on the catalyst, and it is extremely difficult to change only the molecular weight distribution.

[0005]

[Means for Solving the Problems] The present inventors have conducted intensive studies on a method for solving the above-mentioned problems and producing a polymer having a wide molecular weight distribution, and have completed the present invention.

That is, the present invention provides a method for polymerizing α-olefin using a solid catalyst obtained by supporting titanium halide on magnesium halide and a catalyst consisting of an organometallic compound, in which at least one This is a method for polymerizing α-olefins, which comprises polymerizing α-olefins in the presence of a branched alkyl alkoxysilane compound and a titanium, zirconium, or hafnium compound having at least one aromatic compound as a ligand.

In the present invention, the solid catalyst obtained by supporting titanium halide on magnesium halide is preferably supported with various electron-donating compounds such as ethers, esters, alkoxysilanes, amines, and amides. Among these, it is preferable to use a solid catalyst in which titanium tetrachloride and an aromatic diester are supported on magnesium halide because it is possible to produce products with a molecular weight distribution ranging from narrow to wide depending on the conditions.

[0008] In the present invention, as the magnesium halide used to produce the solid catalyst, substantially anhydrous magnesium halide can be used, and even those containing water, usually not more than a few percent, can be used.

As the magnesium halide, magnesium chloride, magnesium bromide, complexes of these with ethers or monoesters, or eutectics of magnesium chloride and magnesium bromide can be used.

As the phthalic acid diester suitable as the aromatic diester, esters of phthalic acid and alcohols having 1 to 12 carbon atoms can be preferably used, such as dimethyl phthalate, diethyl phthalate, dipropyl phthalate, and dibutyl phthalate. , dioctyl phthalate, didecyl phthalate, diphenyl phthalate, dibenzyl phthalate, di-2-ethylhexyl phthalate, etc., as well as diesters such as butylbenzyl phthalate and ethylhexyl phthalate, which have different alcohols forming two ester bonds. Also available.

[0011] As the tetravalent titanium halide suitably used in the present invention, chlorine can be exemplified as the halogen, and those in which some of the halogens have been replaced with alkoxy groups can also be used, but particularly preferred are , titanium tetrachloride is used. Here, the halogenated titanium compound can also be used by forming a complex with a diester of phthalic acid in advance.

As the alkoxysilane used in the present invention, branched alkyl alkoxysilanes can be used, and those having 1 to 3 alkoxy groups can be used. Examples of branched alkyl groups include branched alkyl groups having 1 to 12 carbon atoms, such as isopropyl group, isobutyl group, t-butyl group, 1-methylbutyl group, and cyclopentyl group, and examples of alkoxy groups include methoxy, ethoxy, propoxy,
Examples include butoxy and pentoxy groups. At least one branched alkyl group is sufficient here, and some of the alkyl groups may be straight-chain alkyl groups. Further, the alkoxy group may be a straight chain or a branched one.

The titanium, zirconium or hafnium compounds having at least one aromatic compound as a ligand used in the present invention include cyclopentadiene or a compound in which part or all of its hydrogen is substituted with an alkyl group, or Examples include fused cyclic compounds of cyclopentadiene such as indenyl groups and fluorenyl groups, or compounds in which some or all of the hydrogens are substituted with alkyl groups, and when these fused cyclic compounds are used as ligands, titanium It is also possible to coordinate to a zirconium or hafnium compound and then hydrogenate it. The central metal of these compounds is preferably trivalent or tetravalent, and trivalent or tetravalent titanium compounds are particularly preferred. A titanium, zirconium or hafnium compound having at least one of these aromatic compounds as a ligand can be added to the polymerization system together with the solid catalyst component described above, a branched alkyl alkoxy compound, and an organometallic compound described below. ,In some cases,
It can also be used by being present in the solid catalyst component, and in this case it is not necessary to add it at the time of polymerization. During polymerization, the ratio of the titanium compound to the solid catalyst used is 1:1 to 0.
0001:1 molar ratio is preferred, and 0.0001
Below this, there is almost no effect of widening the molecular weight distribution.

[0014] As for the method of making it exist in the solid catalyst component, it is possible to use it in combination with the titanium compound used for producing the solid catalyst mentioned above when producing the solid catalyst component.
The simplest way to produce a catalyst with good performance is to co-pulverize a carrier, titanium halide, and a titanium, zirconium, or hafnium compound having at least one aromatic compound as a ligand. It is preferable to use an electron-donating compound such as

[0015] Furthermore, by heat-treating the co-pulverized product with a hydrocarbon compound or a halogenated hydrocarbon compound, the activity of the catalyst or the stereoregularity of the obtained polymer can be further enhanced.

Alternatively, the solid catalyst component can be dispersed in a solvent that does not dissolve the titanocene compound, and the titanocene compound can be added to the slurry of the transition metal catalyst component while being dissolved in the solvent. By doing so, it is possible to effectively widen the molecular weight distribution using a relatively small amount of titanocene compound, and it is also possible to easily obtain catalyst systems with various molecular weight distributions. The solid catalyst component may be used after being treated with a small amount of olefin in the presence of the organometallic catalyst component and, if necessary, the branched alkyl alkoxysilane.

Solvents that do not dissolve the titanocene compound include saturated hydrocarbon compounds, specifically propane, butane,
Pentane, hexane, heptane, octane, undecane, dodecane or mixtures thereof are utilized.

Further, as a solvent for dissolving the titanocene compound, an aromatic hydrocarbon compound having 1 to 20 carbon atoms or a halogenated hydrocarbon compound, specifically benzene, toluene, ethylbenzene, xylene, cumene, cymene, or hydrogen thereof. Examples include those in which a portion of is substituted with a halogen element, methylene dichloride, chloroform, ethylene dichloride, and trichloroethane. Here, the slurry concentration is 0.1 to 500 g/liter,
Titanocene compound concentration is 0.001 to 100g
/liter is preferred.

[0019] When adding the solution of the titanocene compound to the slurry of the transition metal catalyst component, it is preferably done under stirring, and the concentration of each is preferably such that the titanocene compound precipitates when the two are mixed. .

A preferred solid catalyst component is produced as follows. The ratio of phthalic acid diester and titanium halide used in co-pulverization is 0.3:1 to 1:0.
3 molar ratio, more preferably 0.5:1 to 1:0
．． It is 5. If it exceeds this range, the activity and stereoregularity of the resulting polymer will not be sufficient when the catalyst is used for polymerization.

[0021] The ratio of titanium halide to magnesium halide is 1:0.001 to 1:0.
．． 5 weight ratio is preferable.

Further, when adding titanium, zirconium, or hafnium compounds having at least one aromatic compound as a ligand by co-pulverization, the ratio of use with titanium halide is 1:1 to 0 as described above. .00
A molar ratio of 0.01:1 is preferable, and if it is less than 0.0001, there is little effect of widening the molecular weight distribution.

[0023] The co-pulverized product is further heated to a temperature of 50°C to 150°C, preferably a hydrocarbon compound having 1 to 12 carbon atoms or a compound in which one or all of its hydrogen atoms have been replaced with chlorine, bromine, or iodine, if necessary. It is processed.

During co-pulverization, it is also possible to further add an inert carrier to the catalyst system, and in addition to inorganic materials such as silica and alumina, polyethylene, polypropylene,
Polymer compounds such as polystyrene can be used.

[0025] In the present invention, organoaluminum can preferably be used as the organometallic compound, and more preferably trialkylaluminum such as trimethylaluminum, triethylaluminum, tripropylaluminum, and tributylaluminium, and one or two hydrocarbon residues thereof. An example is an alkyl aluminum halogen in which is substituted with chlorine or bromine.

The ratio of organometallic compound and alkyl alkoxysilane to titanium in the solid catalyst component is 1:1:1 to 1:10000:10000 molar ratio, usually 1:1:1 to 1:1000:1000 molar ratio. It is a ratio.

In the present invention, the titanium, zirconium, or hafnium compound having at least one aromatic compound as a ligand can be present in the catalyst containing the titanium compound as described above, and can also be present in the polymerization system. It can also be used by adding it together with the above catalyst. At this time, a titanium, zirconium, or hafnium compound having at least one aromatic compound as a ligand may be added at the same time as the polymerization starts, or may be added after a specific amount has been polymerized, or it may be added in two or more tanks. When performing polymerization using a reactor in which two polymerization tanks are connected, it is possible to add the compound only to the subsequent polymerization tank, or to change the amount added. The amount added is the same ratio as the method of introducing into the solid catalyst described above,
Alternatively, it is common to use about 2 to 10 times as much.

[0028] In the present invention, the α-olefin is
It means one or a mixture of two 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,
Examples include pentene-1, hexene-1, heptene-1, octene-1, and 4-methylpentene-1.

In the present invention, the method for polymerizing α-olefin is not particularly limited, and various known methods can be employed.
Any of the following methods can be employed: 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 using substantially no liquid medium.

[0030] During polymerization, the temperature is generally from room temperature to 150°C, and the pressure is from normal pressure to 100 kg/cm2.
In addition to the homopolymerization of α-olefins, this polymerization method can be preferably used for random or block copolymerization with each other or with ethylene. Alternatively, a block copolymer with excellent physical properties can be obtained by adding a hafnium compound.

It is also possible to connect two or more reaction vessels for continuous polymerization, and in this case, it is also possible to produce a polymer with a wider molecular weight distribution by changing the hydrogen concentration in each vessel. Furthermore, it is possible to provide polyolefins with high activity per solid catalyst even under conditions where the hydrogen concentration is relatively low.

In the catalyst system of the present invention, it is easy to lower the hydrogen concentration in the later stage polymerization tank, and a polymer with a higher molecular weight can be produced in the later stage reaction tank. Although the reason is not clear, in the present invention, the hydrogen concentration can be sufficiently lowered without purging the hydrogen from the later stage polymerization tank. Compared to a method in which the molecular weights of the polymers obtained in each tank are differentiated by purging hydrogen, no lumps or the like will be seen on the surface of the molded product even if the molecular weight difference is large.

[0033] Therefore, by using the method of the present invention, it is easy to lower the hydrogen concentration in the reaction tank at a later stage, and by adopting such a method, a polymer with a wider molecular weight distribution can be obtained. .

[0034]

[Examples] The present invention will be further explained below with reference to Examples.

Example 1 A vibratory mill equipped with four grinding pots each having an internal volume of 4 liters and containing 9 kg of steel balls each having a diameter of 12 mm was prepared. 300 g of magnesium chloride, 75 ml of diisobutyl phthalate, 60 ml of titanium tetrachloride, and 7 g of dicyclopentadienyl titanium dichloride were added to each pot in a nitrogen atmosphere and pulverized for 40 hours.

[0036] Put 10 g of the above co-pulverized product into a 200 ml flask, add 60 ml of toluene, and heat at 114°C for 30 minutes.
The mixture was stirred for a minute, then allowed to stand, and the supernatant liquid was removed. Next, the solid content was washed three times with 100 ml of n-heptane at 20°C and further dispersed in 100 ml of n-heptane to obtain a transition metal catalyst component slurry. The resulting transition metal catalyst component contained 2.2 wt% titanium and 14.5 wt% diisobutyl phthalate.

Prepare a fully dried autoclave with an internal volume of 5 liters and purify it with nitrogen, and add 100 ml of heptane.
To the mixture were added 0.2 ml of triethylaluminum diluted to 0.2 ml, 0.1 ml of diisopropyldimethoxysilane, and 15 mg of the above transition metal catalyst component, and 1.5 kg of propylene and 3.2 N liters of hydrogen were added thereto, followed by polymerization at 70° C. for 2 hours. After the polymerization, unreacted propylene was purged and the mixture was dried at 80° C. for 8 hours and weighed to obtain 640 g of polypropylene. In addition, the intrinsic viscosity (hereinafter abbreviated as η) of polypropylene measured with a tetralin solution at 135°C is 1.60, and the boiling n-heptane extraction residue (
Weight of extracted residual polymer/weight of polymer before extraction: 10
0 fraction (hereinafter abbreviated as II) is 97.9%, gel permeation chromatography shows 1 at 135°C.
, 2,4-trichlorobenzene as a solvent (hereinafter referred to as MW/MN).
) was 7.9.

Comparative Example 1 A catalyst was synthesized without using dicyclopentadienyl titanium dichloride, and the amount of hydrogen added during polymerization was 1.7N.
The same procedure as in Example 1 was carried out except that the η of the polymer obtained per liter was almost the same, and 665 g of polymer was obtained.
I got it. The η of this powder is 1.63, and the II is 98.2.
, MW/MN was 6.1.

Comparative Example 2 Changed to 0.1 ml of diisopropyldimethoxysilane,
The same procedure as in Example 1 was carried out except that 0.1 ml of phenylmethyldimethoxysilane was used. When weighed, 580 g of polypropylene was obtained. Also, η of polypropylene is 1.66, II is 98.0%, and MW/MN is 6.7
Met.

Example 2 The procedure of Example 1 was repeated except that dicyclopentadienyl zirconium dichloride was used instead of dicyclopentadienyl titanium dichloride, and 640 g of polymer was obtained. The η of this powder is 1.62, and the II is 97.9%.
, MW/MN was 7.6.

Example 3 Changed to 0.1 ml of diisopropyldimethoxysilane,
The same procedure as in Example 1 was carried out except that 0.1 ml of t-butylmethyldimethoxysilane was used, and 680 g of polymer was obtained.
I got it. This powder has an η of 1.59 and an II of 97.
8%, and MW/MN was 8.5.

[0042]

Effects of the Invention By carrying out the method of the present invention, it is possible to produce a highly stereoregular poly-α-olefin with a relatively wide molecular weight distribution, which is of industrial value.

[Brief explanation of the drawing]

FIG. 1 is a flowchart diagram to aid understanding of the present invention.

Claims (2)

[Claims] Claim 1: A method for polymerizing α-olefin using a solid catalyst obtained by supporting titanium halide on magnesium halide and a catalyst comprising an organometallic compound, in which at least one branched alkyl alkoxysilane is added during polymerization. A method for polymerizing an α-olefin, which comprises polymerizing an α-olefin in the presence of a titanium, zirconium or hafnium compound having at least one aromatic compound as a ligand. 2. The method according to claim 1, wherein the branched alkyl alkoxysilane compound is a monoalkoxy, dialkoxy or trialkoxy silane compound.