JP3408594B2 - Method for producing polyolefin - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an olefin polymerization catalyst and a method for producing a polyolefin using the catalyst.
More specifically, it relates to a method for producing a highly stereoregular poly α-olefin.

[0002]

2. Description of the Related Art Recently, it has been known that stereospecific polymerization is possible in the polymerization of .alpha.-olefins (mainly propylene) with a metallocene catalyst system. For example, atactic polypropylene (Makromol. Chem., Rapid Commun.
4,417-421 (1983), JP-A-58-19309, isotactic polypropylene (Angew.Chem.Int.Ed.Engl.,
24, 507-508 (1983), J. Am. Chem. Soc., 106, 6355 (1984), JA
m.Chem.Scc., 109,6544 (1987), Chem.Lett., 1853-1856 (19
89), JP-A-2-76887)), syndiotactic polypropylene (J. Am. Chem. Soc., 110, 6255, (1988)) and the like can be produced. The ligand structure and the three-dimensional structure of the zirconium complex are the key to the development of these stereospecificities. However, the type and performance of metallocene compounds capable of producing industrially important isotactic polypropylene are very limited. For example, ethylene bis (indenyl) zirconium dichloride and ethylene bis (tetrahydroindenyl) zirconium dichloride disclosed in JP-A-63-295607 (Cosden) can produce isotactic polypropylene in the presence of methylaluminoxane. Its stereoregularity is relatively low at about 95% in mm%, and the melting point of the polymer is low at 135 ° C to 146 ° C.
Even isotactic polypropylene obtained from dimethylsilylenebis (indenyl) zirconium dichloride (USP 5,017,714) in which the cross-linking portion is changed to silicon has a low melting point of 149 ° C to 153 ° C. In addition, these C2 symmetric complexes have two structural isomers, a racemic body and a meso body, and only one racemic body can produce isotactic polypropylene. The meso product produced in (1) produces an atactic polymer which is industrially unfavorable. Therefore, a complicated purification process for separating the meso form is required, and there is a drawback that the cost for producing the complex increases.

Further, JP-A-1-301704, JP-A-1-319489, JP-A-2-76887, and Chem. Let.
Dimethylsilylenebis (2,3,5-trimethylcyclopentadienyl) zirconium dichloride disclosed in t., 1853 (1989) is a high isotactic polypropylene of 99% or more in mm% in the presence of methylaluminoxane. Although it can be produced, this complex also has two structural isomers structurally, a racemic body and a meso body, and one isomer (racemic body) capable of producing isotactic polypropylene is the other. A very complicated purification process is required to purify and separate from the (meso form). Other bis (t-butylcyclopentadienyl)
Zirconium dichloride (Organometallics, 10, 2061
(1991)), dimethylsilylene bis (3-t-butyl-
5-Methylcyclopentadienyl) zirconium dichloride (USP 5,132,262) and the like also obtain highly isotactic polypropylene in the presence of methylaluminoxane, but in this case, it is necessary to separate the racemic form and the meso form,
Separation and purification of isomers are very complicated.

The above is an example of the prior art for producing isotactic polypropylene by a C2 symmetric complex requiring separation of isomers. Recently, a C1 symmetric complex requiring no separation of isomers has been disclosed. Came. Dimethylsilylene (indenyl) (fluorenyl) zirconium dichloride (EP 0528287) is based on this idea, but in the polymerization of propylene, it gives only atactic polypropylene and not stereoregular polymerization. A C1 symmetric complex based on a similar idea, Tobin J. Marks et al. (J. A.
m. Chem. Soc., 115,3326 (1993)) gave isotactic polypropylene with methylaluminoxane as a cocatalyst. However, the reported complex is an expensive complex in which a chiral substituent is introduced, and -4
Lowering to a low temperature of 5 ° C does not give polypropylene of sufficient stereoregularity and molecular weight. According to Chien et al., Ethylidene (tetramethylcyclopentadienyl) (indenyl) titanium dichloride gives a thermoplastic elastomer with a melting point of about 60 ° C when propylene polymerization is carried out in combination with methylaluminoxane (J. Am. .Ch
em. Soc., 112, 2030 (1990) J. Am. Chem. Soc., 113,8
569 (1991) Macromol., 24, 850 (1991) Macromol., 25,
1242 (1992) J. Poly. Sci. Part A: Poly. Chem., 30,
2601 (1992)), which does not give highly isotactic polymers. Further, dimethylsilylene (fluorenyl) (t-butylamino) zirconium dichloride (WO 92/05204) disclosed by Canich is also an example of giving isotactic polypropylene in an asymmetric type, but has a low melting point of 145 ° C. In addition, it has a drawback that the activity per complex is extremely low. In addition, conventionally, isopropylidene (methylcyclopentadienyl) (fluorenyl) zirconium dichloride (Makromol. Chem., Macromol. S
ymp., 48/49, 253 (1991), JP-A-3-9913). However, this complex gives a syndio-isoblock polymer upon propylene polymerization (3% at mm%).
2%), which does not give industrially more important isotactic polypropylene.

Recently, dimethylsilylenebis (2-methyl, a modified C2 symmetric metallocene compound has been modified.
It has been reported that a combination of 4-isopropyl-indenyl) zirconium dichloride and methylaluminoxane can polymerize high molecular weight isotactic polypropylene (Spaleck, Angew. Chem. Int. Ed. Eng.
l., (1993)) has a low melting point of the polymer and does not show sufficient physical properties. These catalyst systems are characterized by a significantly higher activity per transition metal. Biscyclopentadienyl zirconium dichloride is a metallocene compound that has been widely known and classically used. A technique for polymerizing olefins using a catalyst composed of this compound and aluminoxane is disclosed by Kaminsky et al. (JP-A-58-19309). However, regarding the polymerization of isotactic polypropylene, the stereoregularity and melting point of the produced polypropylene are low, which is not practical.
Further, as polypropylene obtained with a metallocene catalyst, those having a specific structure are known as isoblock PP and hemiiso PP, but according to the facts described, they all have a low melting point and are different from the properties of polypropylene obtained by the present invention. Is. Furthermore, the polypropylene obtained by the conventional Ziegler type catalyst does not have sufficient stereoregularity, and the atactic component is present in the resin, so ISO / DIS
The xylene-insoluble matter ratio by the xylene-soluble matter measuring method described in 1873-1 is not sufficiently high.

[0006]

When the conventional metallocene catalyst is used in an industrially preferable polymerization temperature range of 50 ° C. to 80 ° C., a polymer having a low molecular weight is obtained, and a poly α having a molecular weight of industrial value is obtained. Not suitable for the production of olefins. Further, generally, in high temperature polymerization (50 ° C. to 80 ° C.), the stereoregularity of the polymer produced tends to be lowered.
The present invention is intended to produce a poly-α-olefin having a sufficiently high molecular weight and high stereoregularity even in high temperature polymerization.

[0007]

Means for Solving the Problems As a result of intensive studies for solving the above problems, as a result, C1 symmetry as represented by the formula [1] and an alkyl substituent at the 2 position counted from the bridging portion are shown. The present inventors have found that a high molecular weight and highly stereospecific poly-α-olefin can be polymerized by a combination of a metallocene compound and an aluminoxane cocatalyst. The main catalyst component [A] of the present invention has a C1 symmetric structure and is represented by the formula [1].

[Chemical 2] (In the formula, M is Ti, Zr or Hf , and R ¹ , R
² , R ³ is a hydrocarbon group having 1 to 20 carbon atoms other than a hydrogen atom, or an alkylsilyl group, and may be the same or different, but R ² and R ³ have the same group at the same time. Excluding things. R ⁴ , R ⁵ , R ⁶ and R ⁷ are a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms or an alkylsilyl group, and they may be the same or different, but R ⁴ , R ⁷ Except when are simultaneously hydrogen atoms. In addition, adjacent R ¹ to R ⁷ on the cyclopentadienyl ring
May form a ring with each other via a hydrocarbon group. In the formula, Y is an alkylene group, a silylene group, or a germylene group, and n is 1 . R ⁸ and R ⁹ are hydrogen atoms and have 1 carbon atom
~ 20 hydrocarbon groups or alkylsilyl groups,
They may be the same or different from each other. They may also form a ring via a hydrocarbon group. X ¹ , X
² is a hydrogen atom, a hydrocarbon group having 1 to 20 carbon atoms, a halogen, an alkylsilyl group or a silylalkyl group. )

Further, a metallocene compound having C1 symmetry as represented by the formula [2] and having an alkyl substituent at the 2 position counted from the bridging portion is more preferable.

[Chemical 3] (In the formula [2], M is Ti, Zr or Hf , and X ¹¹
And X ¹² may be the same or different and each represents a hydrogen atom, a hydrocarbon group having 1 to 10 carbon atoms, an alkylsilyl group or a halogen atom. R ¹¹ and R ¹² mean a hydrogen atom, a hydrocarbon group having 1 to 10 carbon atoms, or an alkylsilyl group, and one of R ¹¹ and R ¹² is a hydrogen atom. R ¹³ is a hydrocarbon group having 1 to 10 carbon atoms other than a hydrogen atom, or an alkylsilyl group. R ¹⁴ , R ¹⁵ and R ¹⁶ are each a hydrogen atom, a hydrocarbon group having 1 to 10 carbon atoms, or
It means an alkylsilyl group, which may be the same or different from each other, but excludes those in which all three are hydrogen atoms at the same time. In the formula, Y is an alkylene group, a silylene group, or a germylene group, and n is 1 . R ¹⁸ and R ¹⁷ are a hydrogen atom, a hydrocarbon group having 1 to 20 carbon atoms or an alkylsilyl group, and may be the same or different from each other. They may also form a ring via a hydrocarbon group. )

The substituent at the position specified in the formula [2] on the cyclopentadienyl ring of the metallocene compound of the present invention (R ¹¹ or R ¹² , R ¹³ is a hydrocarbon group having 1 to 10 carbon atoms ( Alkyl, aryl, alkylaryl, arylalkyl, etc.) or an alkylsilyl group (trialkylsilyl group, triarylsilyl group, etc.), but preferably a tert-butyl group having 4 or more carbon atoms,
It is a bulky substituent such as an iso-butyl group and a sec-butyl group. It is also possible to use it as a catalyst component in combination with two or more metallocene compounds. A preferred central metal in the metallocene compound as described above is
Di Rukoniumu.

Specific examples of the transition metal compound [A] in which M ¹ is zirconium can be given below. (C1 symmetry) dimethylsilylene (tetramethylcyclopentadienyl) (3-t-butylcyclopentadienyl) zirconium dichloride, dimethylsilylene (tetramethylcyclopentadienyl) (3-neomenthylcyclopentadienyl) zirconium dichloride , Dimethylsilylene (tetramethylcyclopentadienyl) (3
Menthylcyclopentadienyl) zirconium dichloride, methylmethylene (tetramethylcyclopentadienyl) (indenyl) zirconium dichloride.

[0011] More preferably, Lee Sopuropiriden (2-
Methyl-4-methylcyclopentadienyl) (2-methyl-3-methylindenyl) zirconium dichloride,
Isopropylidene (2-methyl-4-tbutylcyclopentadienyl) (3-methylindenyl) zirconium dichloride, isopropylidene (2-methyl-4-tbutylcyclopentadienyl) (3-tbutylindenyl) Zirconium dichloride, dimethyl silylene (2-
Methyl-4-methylcyclopentadienyl) (3-methylindenyl) zirconium dichloride, dimethylsilylene (5-methyl-4-tbutylcyclopentadienyl) (2-methyl-3-methylindenyl) zirconium dichloride, Dimethylsilylene (2-methyl-4-t
Butylcyclopentadienyl) (3-t-butylindenyl) zirconium dichloride, isopropylidene (2-
Methyl-4-methylcyclopentadienyl) ( 2,3-
Dimethyl-4-ethylcyclopentadienyl) zirconium dichloride, isopropylidene (2-methyl-4-)
t-butylcyclopentadienyl) ( 2,3- dimethyl-
4-ethylcyclopentadienyl) zirconium dichloride, isopropylidene (2-methyl-4-tbutylcyclopentadienyl) ( 2,3- ditbutyl-4-methylcyclopentadienyl) zirconium dichloride, isopropylidene ( 2-Methyl-4-methylcyclopentadienyl) (3-methylindenyl) zirconium dimethyl, isopropylidene (2-methyl-4-tbutylcyclopentadienyl) (3-methylindenyl) zirconium dimethyl, isopropylidene (2-ethyl-4-
t-butylcyclopentadienyl) (3-t-butylindenyl) zirconium dimethyl, isopropylidene (4-
Methyl-cyclopentadienyl) (2-methyl-3-t
Butylindenyl) zirconium dichloride, isopropylidene (4-t-butyl-cyclopentadienyl)
(2-methyl -3-t-butyl-indenyl) zirconium dichloride, dimethylsilylene - etc. (4-t-butyl-cyclopentadienyl) (2-methyl -3-t-butyl-indenyl) titanium dichloride de can be mentioned . Zirconium metal at the above-mentioned zirconium compounds titanium metal, can also be exemplified transition metal compounds in place of the hafnium metals.

The aluminoxane used in the catalyst is an organoaluminum compound represented by the general formula [3] or the general formula [4].

[Chemical 4]

[Chemical 5] R ²² is a methyl group, an ethyl group, a propyl group, a butyl group,
A hydrocarbon group such as an isobutyl group, preferably a methyl group or an isobutyl group. m is an integer of 4 to 100, preferably 6 or more and particularly 10 or more.
A method for producing this type of compound is known, and for example, a method in which a salt having crystallization water is added to a hydrocarbon solvent suspension of (copper sulfate hydrate, aluminum sulfate hydrate) and trialkylaluminum is exemplified. You can do it.

Aluminoxanes represented by the general formulas [5] and [6] may also be used.

[Chemical 6]

[Chemical 7] R ²³ is a methyl group, an ethyl group, a propyl group, a butyl group,
A hydrocarbon group such as an isobutyl group, preferably a methyl group or an isobutyl group. R ²⁴ is a methyl group,
It is a hydrocarbon group such as an ethyl group, a propyl group, a butyl group and an isobutyl group, or a halogen or hydrogen atom such as chlorine and bromine, and a hydroxyl group, and is different from R ¹³ .
R ¹⁴ may be the same or different. m is usually 1
To an integer of 100, preferably 3 or more, m
+ N is 4 to 100, preferably 6 or more. In the general formulas [5] and [6],

[Chemical 8] It may be a block-shaped combination or a regular or irregularly connected one. The method for producing such an aluminoxane is the same as that for the aluminoxane represented by the general formula described above. Instead of one kind of trialkylaluminum, two or more kinds of trialkylaluminum are used, or one or more kinds of trialkylaluminum and one kind are used. The above dialkylaluminum monohalides may be used.

The metallocene catalyst component and the aluminoxane catalyst component used in the present invention can be used in combination with a catalyst component other than this component. For example, these characteristic metallocene components can be used by supporting them on an inorganic carrier. Examples of usable carriers include silica, inorganic oxides typified by alumina, and inorganic halides typified by magnesium chloride and manganese chloride. When the carrier is used, the carrier may be treated with an organic aluminum in advance. Further, the carrier may be coated with an aluminoxane. In addition to these metallocene catalyst components, an organic donor compound can be used in combination.
For example, alkoxysilanes, esters, ethers, alkoxyesters, ketoesters, ketoethers and the like can be exemplified.

In the method of the present invention, the olefin used for the polymerization is ethylene, propylene, 1-butene, 2-
Examples thereof include olefins such as butene, 1-pentene, 4-methyl-1-pentene, cyclopentene, norbornene, cyclopentadiene, butadiene, 1,5-hexadiene, 1,4-hexadiene, cyclic olefins, and dienes. I can. It is also possible to polymerize a mixture of two or more of these. The polymerization method used in the present invention may be either liquid phase polymerization or gas phase polymerization. The liquid phase polymerization solvent is a hydrocarbon compound capable of dissolving both zirconium compound and aluminoxane components, such as benzene, toluene, o-xylene, m-xylene, p-xylene, ethylbenzene, butylbenzene, mesitylene and chlorobenzene. The aromatic hydrocarbons are used, and toluene and xylene are preferable. Further, when the metallocene catalyst component of the present invention is used for polymerization, a hydrocarbon solvent such as isobutane, butane, pentane, hexane, heptane, cyclohexane, paraffin, decane, dodecane is used as a solvent for slurry polymerization. can do.

The metallocene catalyst component of the present invention can be used together with various organoaluminum compounds in the polymerization system. For example, trimethyl aluminum, triethyl aluminum, triisobutyl aluminum, tributyl aluminum, diethyl aluminum dichloride, ethyl aluminum sesquichloride, ethyl aluminum monochloride, diethyl aluminum ethoxide, diethyl aluminum methoxide, ditbutyl methoxide,
Examples thereof include bis (2,6 di-t-butylphenoxy) aluminum methyl.

The polymerization temperature is not particularly limited, but is -78 ° C to 300 ° C, preferably 0 ° C to 100 ° C, and more preferably 30 ° C to 80 ° C. Further, the polymerization temperature may be changed in two or more steps during the polymerization. The molecular weight at the time of polymerization can be adjusted by known means, for example, selection of temperature or introduction of hydrogen. Hydrogen can be used as the molecular weight regulator used during the polymerization. Further, an organoaluminum compound typified by trimethylaluminum may be used as a chain transfer agent other than hydrogen. The hydrogen concentration used may be the same throughout the polymerization, or different hydrogen concentrations may be used in multiple stages. The zirconium compound of the present invention can also be supported on a carrier such as silica, alumina or magnesium chloride to prepolymerize an olefin, and can be used in a solvent or monomer in which both zirconium compound and aluminoxane components cannot be dissolved. I can. As the catalyst component, a mixture of both components of the zirconium compound and aluminoxane may be supplied to the reaction system, or both components may be supplied to the reaction system. Further, it may be brought into contact with the promoter component in the reactor. In either case, there is no particular limitation on the concentration molar ratio of both components in the polymerization system, but a Zr concentration of 10 is preferred.
^-3 to 10 ^-10 mol / l, and the molar ratio of Al / Zr is preferably 10 or more, particularly preferably 100 or more. The olefin pressure of the reaction system is not particularly limited,
The pressure is preferably from normal pressure to 50 kg / cm ² G, and the polymerization temperature is not limited, but is preferably from -30 ° C to 100 ° C. The molecular weight at the time of polymerization can be adjusted by known means, for example, selection of temperature or introduction of hydrogen.

[0018]

EXAMPLES Next, the present invention will be specifically described by way of examples. The analytical instruments used for measuring physical properties are as follows. Mass spectrometer JMS-AX500 manufactured by JEOL Ltd. Example 1 [Isopropylidene (2-methyl-4-tbutylcyclopentadienyl) (3-t-butylindenyl) zirconium dichloride] All reactions were performed under an inert gas atmosphere. I did it in. The reaction vessel used was previously dried. Dry TH in a 300 ml glass reaction vessel
F100 ml was added and dimethyl (2-methyl-
3 g of 4-tbutylcyclopentadienyl) (3-tbutylindenyl) methane was dissolved, and 15 ml of a 1.6 mol / l n-BuLi hexane solution was added under ice cooling. After reacting for 1 hour at room temperature, THF was distilled off under reduced pressure.
While cooling, 50 ml of methylene chloride was added. Zirconium tetrachloride 2.63 in a separately prepared flask
g was charged and 50 ml of methylene chloride was added and suspended. This was cooled, and the suspension of the lithium salt of dimethyl (2-methyl-4-tbutylcyclopentadienyl) (3-t-butylindenyl) methane was added with a cannula while cooling. After reacting at room temperature for 2 hours, the produced lithium chloride was removed and the solution was concentrated to obtain orange crystals (yield 0.8 g). The physical properties of this compound are shown below.
The Mass spectrum was measured by the direct introduction method. Elemental _{analysis: (C 26 H 34 ZrCl 2} ) Calculated (%): C; 61.39, H; 6.74 Found (%): C; 61.11, H; 6.59 Mass m / e = 508

Example 2 [Polymerization] S with an internal volume of 1.5 liter which had been sufficiently replaced with nitrogen.
US autoclave with purified toluene 300 ml. Tosoh Akzo methylaluminoxane (2.
7M) and 15 ml of isopropylidene (2-methyl-
0.02 mmol of 4-tbutylcyclopentadienyl) (3-tbutylindenyl) zirconium dichloride was sequentially added, and the mixture was cooled to 3 ° C. Then propylene 2mo
After the reaction in which 1 was charged and polymerization was carried out for 1 hour, the catalyst component was decomposed with methanol and the obtained polypropylene was dried. As a result, high isotactic polypropylene is 2
4 g was obtained. The molecular weight Mw of the polymer was 560000.

Example 3 [Copolymerization] 300 ml of purified toluene was added to an autoclave made of SUS having an internal volume of 1.5 liters, which was sufficiently replaced with nitrogen. Toso-Akzo methylaluminoxane (2.7 M per aluminum) 15 ml and isopropylidene (2-methyl-4-tbutylcyclopentadienyl) (3-tbutylindenyl) zirconium dichloride 0.02 mmo
1 was added sequentially and cooled to 3 ° C. Then propylene 2
Mol was added and ethylene pressure of 1 kg / cm ^{2 was} applied. After the polymerization reaction for 1 hour, the polypropylene was obtained by decomposing the catalyst component with methanol. As a result, 41 g of EPR having good randomness was obtained. The molecular weight Mw of the polymer was 670000.

[0021]

INDUSTRIAL APPLICABILITY According to the present invention, by using a novel metallocene compound having a cross-linking ligand having an asymmetric substituent, a polyolefin having high molecular weight and high stereospecificity can be efficiently produced in olefin polymerization. It can be manufactured well.

─────────────────────────────────────────────────── ─── Continuation of front page (56) References JP-A-5-43619 (JP, A) JP-A-5-209013 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C08F 4/64-4/658 CA (STN)

Claims (2)

(57) [Claims] 1. A metallocene compound represented by formula [A] [1]: (In the formula, M is Ti, Zr or Hf , and R ¹ , R
² , R ³ is a hydrocarbon group having 1 to 20 carbon atoms other than a hydrogen atom, or an alkylsilyl group, and may be the same or different, but R ² and R ³ have the same group at the same time. Excluding things. R ⁴ , R ⁵ , R ⁶ and R ⁷ are a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms or an alkylsilyl group, and they may be the same or different, but R ⁴ , R ⁷ Except when are simultaneously hydrogen atoms. In addition, adjacent R ¹ to R ⁷ on the cyclopentadienyl ring
May form a ring with each other via a hydrocarbon group. In the formula, Y is an alkylene group, a silylene group, or a germylene group, and n is 1 . R ⁸ and R ⁹ are hydrogen atoms and have 1 carbon atom
~ 20 hydrocarbon groups or alkylsilyl groups,
They may be the same or different from each other. They may also form a ring via a hydrocarbon group. X ¹ , X
² is a hydrogen atom, a hydrocarbon group having 1 to 20 carbon atoms, a halogen, an alkylsilyl group or a silylalkyl group. ) [B] An olefin polymerization catalyst containing aluminoxane as a catalyst component. 2. A method for producing isotactic polypropylene, which comprises using the olefin polymerization catalyst according to claim 1.