JP3284320B2 - Method for producing olefin copolymer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a low-melting-point, highly transparent ethylene α-olefin copolymer using a novel metallocene supported catalyst.

[0002]

2. Description of the Related Art Kaminski catalysts (metallocene / methylalumoxane) are widely known as homogeneous catalysts for olefin polymerization. This catalyst system is characterized by a remarkably high activity per transition metal. BACKGROUND ART Biscyclopentadienyl zirconium dichloride (zirconocene dichloride) is a metallocene compound widely known and conventionally used. A technique for copolymerizing ethylene and an α-olefin using a catalyst comprising this compound and methylaluminoxane is disclosed by Kaminsky et al. (JP-A-58-19309). However, in this catalyst system, it is difficult to produce a sufficiently high molecular weight copolymer in an industrially preferable temperature range (50 to 70 ° C.), and at the same time, a linear low density polyethylene having a preferable density is obtained. For this purpose, there is a problem that a large amount of comonomer must be charged into the polymerization system. Further, Yuin et al. Have found that the use of a metallocene compound having a substituent on the cyclopentadienyl ring of a ligand allows a temperature range (5.
(0-70 ° C.), but a high molecular weight copolymer has been successfully obtained, but a large amount of very expensive methylaluminoxane must be used as a cocatalyst, which is problematic from an industrial point of view. Showa 60-35007). Further, Wellborn et al. Have proposed to increase the polymerization activity per aluminoxane by supporting metallocene and aluminoxane on a porous inorganic metal oxide.However, polymerization activity is not sufficiently high, and metallocene and aluminoxane are not sufficiently high. The catalyst has the disadvantage that the polymerization activity of the catalyst decreases with time immediately after contact with the catalyst (JP-A-61-296008). Ishihara et al. Have also tried to increase the polymerization activity per aluminum by using a co-catalyst consisting of methylaluminoxane and another organoaluminum compound, but the effect is not sufficiently improved (JP-A-60-130604). JP-A-60-260602).

[0003]

SUMMARY OF THE INVENTION In view of the above-mentioned problems of the prior art, it is an object of the present invention to provide a catalyst having a high activity per cocatalyst without change with time, a low melting point, a high transparency and a narrow composition distribution. An object of the present invention is to provide a method for producing an ethylene-α-olefin copolymer.

[0004]

Means for Solving the Problems As a result of intensive studies to solve the above problems, the present inventors have succeeded in efficiently synthesizing a novel metallocene compound as shown below, and In addition, the compound having no meso structure is found to be extremely useful as a catalyst component for ethylene-α-olefin copolymerization, and at the same time, this specific metallocene compound is supported on an inorganic oxide carrier, and an organic aluminum The inventors have found that extremely effective catalytic performance can be realized by using the components in combination, and have reached the present invention.

The metallocene compound used in the present invention has the general formula (1)

Embedded image [In the formula (1), M means any transition metal of Ti, Zr, and Hf. X ¹ and X ² may be the same or different from each other and represent a hydrogen atom, a hydrocarbon group having 1 to 10 carbon atoms, an alkylsilyl group, or a halogen atom. R ¹ , R ² , R ³ , R ⁶ , and R ⁷ represent a hydrogen atom, a hydrocarbon group having 1 to 10 carbon atoms, or an alkylsilyl group, and ^one of R ¹ and R ² is hydrogen. Not an atom. R ⁴ and R ⁵ are bonded to each other to form an indenyl ring
Form. Y is a carbon atom or a silicon atom or
It means germanium atom. In the formula, n is an integer of 1 to 3.]. Of these, Y in general formula (1)
Is preferably a metallocene compound having a carbon atom.

[0006]

[0007] Representative synthetic routes of the compounds of the present invention are abbreviated as follows, but are not limited thereto. As an example of the synthesis of a zirconium compound having a substituent on the cyclopentadienyl ring, C ₉ H ₈ (Indene) + BuLi + tBuBr ———— tBu—C ₉ H ₇ tBu—C ₅ H ₅ + BuLi + tBu—C ₅ H ₃ = _{C (CH 3) 2 ----- →} (CH) 2 C (tBu-C 5 H 4) (C 9 H 8 -tBu) (CH) 2 C (tBu-C 5 H 4) (tBu-C _{9 H 8) + 2BuLi ----- →} Li 2 [iPr (tBu-C 5 H 3) (C 9 H 5 -tBu)] Li 2 [iPr (tBu-C 5 H 3) (C 9 H 5 - tBu)] + ZrCl ₄ − →→ Pr (tBu−C ₅ H ₃ ) (C ₉ H ₅ −tBu) ZrCl ₂ A method for producing a bis-substituted cyclopentadienyl bridge type bidentate ligand having a crosslinked structure is known. That is, J.I. Am. Chem. So
c. , 110, 976-978 (1988); A
m. Chem. Soc. , 107, 8103-8110
(191985).

Specific examples of the above metallocene compound are shown below. Here, the numbers indicating the positions of the substituents on the cyclopentadienyl ring are represented by R ¹ and R in formulas (1) and (2).
² and R ³ , R ⁴ , and R ⁵ .
For example, the position of R ² is 4 and the position of R ³ is 3. Ethylene (4-methyl-cyclopentadienyl) (3-methyl-indenyl) zirconium dichloride, ethylene (4
-Tbutyl-cyclopentadienyl) (3-methyl-indenyl) zirconium dichloride, ethylene (4-t
Butyl-cyclopentadienyl) (3-tbutyl-indenyl) zirconium dichloride, ethylene (4-methyl-cyclopentadienyl) (3-tbutyl-indenyl) zirconium dichloride, ethylene (4-methyl-
Cyclopentadienyl) (3-trimethylsilyl-indenyl) zirconium dichloride, isopropylidene (4-methyl-cyclopentadienyl) (3-methyl-
(Indenyl) zirconium dichloride, isopropylidene (4-tbutyl-cyclopentadienyl) (3-methyl-indenyl) zirconium dichloride, isopropylidene (4-tbutyl-cyclopentadienyl) (3-
t-butyl-indenyl) zirconium dichloride,

Dimethylsilylene (4-methyl-cyclopentadienyl) (3-methyl-indenyl) zirconium dichloride, dimethylsilylene (4-tbutyl-cyclopentadienyl) (3-methyl-indenyl) zirconium dichloride, dimethylsilylene (4-tbutyl-
Cyclopentadienyl) (3-tbutyl-indenyl)
Zirconium Mujikurorido, isopropylidene (4-methyl - cyclopentadienyl) (3-methyl - indenyl) zirconium dimethyl, isopropylidene (4-t
Butyl-cyclopentadienyl) (3-methyl-indenyl) zirconium dimethyl, isopropylidene (4-
t-butyl-cyclopentadienyl) (3-t-butyl-indenyl) zirconium dimethyl,

Ethylene (4-methyl-cyclopentadienyl) (3-methyl-indenyl) hafnium dichloride, ethylene (4-tbutyl-cyclopentadienyl)
(3-methyl-indenyl) hafnium dichloride, ethylene (4-tbutyl-cyclopentadienyl) (3-
t-butyl-indenyl) hafnium dichloride, ethylene (4-methyl-cyclopentadienyl) (3-t-butyl-indenyl) hafnium dichloride, ethylene (4
-Methyl-cyclopentadienyl) (3-trimethylsilyl-indenyl) hafnium dichloride, isopropylidene (4-methyl-cyclopentadienyl) (3-methyl-indenyl) hafnium dichloride, isopropylidene (4-tbutyl-cyclopentane) Dienyl) (3-
Methyl-indenyl) hafnium dichloride, isopropylidene (4-tbutyl-cyclopentadienyl) (3
-Tbutyl-indenyl) hafnium dichloride, dimethylsilylene (4-methyl-cyclopentadienyl)
(3-methyl-indenyl) hafnium dichloride, dimethylsilylene (4-tbutyl-cyclopentadienyl) (3-methyl-indenyl) hafnium dichloride, dimethylsilylene (4-tbutyl-cyclopentadienyl) (3-t butyl - indenyl) hafnium Axis <br/> b Lido, but can ani gel.

The aluminum oxy compound (b) used for the catalyst is a partial hydrolyzate of an organoaluminum compound such as trialkylaluminum, dialkylaluminum dichloride and the like. Particularly preferred are aluminoxanes. Aluminoxane is an organoaluminum compound represented by the general formula (3) or (4). General formula (3)

Embedded image General formula (4)

Embedded image R ²⁰ represents a methyl group, an ethyl group, a propyl group, a butyl group,
It is a hydrocarbon group such as an isobutyl group, and is preferably a methyl group. m is an integer of 4 to 100, preferably 6 or more, especially 10 or more. The method for producing this kind of compound is known, for example, a method for obtaining a salt having water of crystallization by adding a trialkylaluminum to a hydrocarbon solvent suspension of (copper sulfate hydrate, aluminum sulfate hydrate). You can do it.

The amount of the component (b) used is not particularly limited, but is preferably in the range of 0.
01 to 70% by weight, more preferably 0.01 to 30%
% By weight. The inorganic oxide carrier component (c) used in the catalyst is not particularly limited, but the following compounds can be exemplified. Examples thereof include silica, alumina, magnesia, aluminosilicate, boron oxide, and calcium oxide. Preferably, those obtained by treating these inorganic oxide carriers fired at a high temperature with an organoaluminum compound are used.

In the method of the present invention, the α-olefin used for copolymerization is propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene,
Decene, 4-methyl-1-pentene, cyclopentene,
Examples thereof include olefins such as cyclopentadiene, butadiene, 1,5-hexadiene and 1,4-hexadiene 1,4-pentadiene, cyclic olefins, and dienes. These two or more comonomers can be mixed and used for copolymerization with ethylene. The fraction of ethylene and these comonomers in the polymer is not particularly limited, but preferably ethylene / comonomer = 100
00 to 0.5, more preferably 1000 to 10
It is. Further, the lower limit of the density range that these copolymers can achieve can be up to 0.80, preferably 0.80.
Used in the range 9 to 0.94.

The polymerization method used in the present invention may be any of liquid phase polymerization, slurry polymerization, and gas phase polymerization.
Preferably, isobutane slurry polymerization or gas phase polymerization is used. Also, multi-stage polymerization is possible. Alternatively, the particle size can be controlled by prepolymerizing an olefin. The organoaluminum compound used in the polymerization is not particularly limited, but is preferably a trialkylaluminum. Further, preferred are triisobutylaluminum, trimethylaluminum and trioctylaluminum compounds. The amount used is 0.001 to 1 mmol / liter in terms of aluminum concentration in the reaction system.
The organic aluminum component at this time may be used as a premix immediately before polymerization. The olefin pressure of the reaction system is not particularly limited, but is preferably from normal pressure to 50 kg.
/ Cm ² G and the polymerization temperature is not limited,
Preferably it is in the range of -30C to 200C. In particular,
Preferably it is in the range of 0 ° C to 80 ° C. Further, the temperature is preferably from 50 to 70 ° C. The molecular weight at the time of polymerization can be adjusted by known means, for example, selection of temperature or introduction of hydrogen.

[0015]

Next, the present invention will be described specifically with reference to examples. The analytical equipment used for physical property measurement is as follows. FT-IR Perkin Elmer (1720X) DSC Perkin Elmer (DSC-7) The molecular weight was evaluated by MFR. MFR (melt flow rate) is measured at a temperature of 190 according to JIS K-6760.
It measured on condition of ° C and a load of 2.16 kg. HLMI is
The measurement was performed under the condition of a load of 21.6 kg. The fraction (SCB) of the comonomer in the ethylene copolymer was evaluated based on the number of branches in the polymer main chain by FT-IR measurement. Specifically, any IR spectrum and differential spectrum of the IR spectrum of the copolymer samples of polyethylene were measured without the peak height of the peak of 1380 cm ^-1 and height of the original spectrum 4250Cm ^-1 branched This value means the number of branches in 1000 carbon atoms of the copolymer main chain.

Example 1 [Isopropylidene (4-tbutyl-cyclopentadienyl) (3-tbutylindenyl) zirconium dichloride] All the reactions were carried out under an inert gas atmosphere.
In addition, the reaction vessel used was previously dried. Dry THF100 was charged into a 300 ml glass reaction vessel, 3 g of dimethyl (4-tbutylcyclopentadienyl) (3-tBuindenyl) methane was dissolved, and 15 ml of a 1.6 Mn-BuLi hexane solution was added under ice cooling. Was. After reacting at room temperature for 1 hour, THF was distilled off under reduced pressure. While cooling this, 50 ml of methylene chloride
added. 2.63 g of zirconium tetrachloride was charged into a separately prepared flask, and 50 ml of methylene chloride was added to suspend the suspension. This is cooled and dimethyl (4-tbutylcyclopentadienyl) (3-tbutylindenyl)
The suspension of the lithium salt of methane was added by cannula with cooling. After reacting at room temperature for 2 hours, lithium chloride produced was removed, and the solution was concentrated to obtain orange crystals. Yield 0.3 g Elementary analysis of this compound is shown below. Elemental analysis value: (C ₂₅ H ₃₂ ZrCl ₂ ) Calculated value (%): C; 60.78, H; 6.53 Actual value (%): C; 60.81, H; 6.48 [Catalyst preparation A 2 g of silica (Davison 955, calcined at 600 ° C. for 8 hours) is charged into a 100 ml nitrogen-purged flask, and 20 ml of dehydrated toluene is added to form a slurry. To this, 0.3 ml of a methylaluminoxane toluene solution (2.5 mol / l) manufactured by Tosoh Akzo was added, and the mixture was reacted at room temperature for 1 hour. Then, the solvent was distilled off under reduced pressure. 7.5 ml of a hexane solution (1 mmol / l) of isopropylidene (4-tBu-cyclopentadienyl) (3-t-Bu-indenyl) zirconium dichloride was added, reacted for 1 hour, and dried under reduced pressure. A solid catalyst was obtained. [Catalyst Preparation B] The same procedure as in Catalyst Preparation Method A was conducted, except that the silica used in Catalyst Preparation A was changed to silica treated with triethylaluminum (1 g of silica was treated with 0.6 mmol of triethylaluminum in hexane). Was. [Polymerization] 1.5 liter of internal volume of S sufficiently purged with nitrogen
A supported catalyst (A or B) is placed in a US autoclave.
Milligram, 3.5 ml of a hexane solution of triisobutylaluminum (0.5 mol / l) and 800 ml of isobutane were charged, and 1-hexene 2 was added.
7 grams, 70 ° C at 3 kg / cm ² ethylene pressure
Polymerization was performed. After polymerization for 1 hour, the polymerization was stopped by purging. The results are shown in Table 1.

Examples 2-3 The procedure of Example 1 was repeated except that the amount of methylaluminoxane used and the amount of complex were changed.
This was performed in the same manner as in Example 1. The results are shown in Table 1.

Examples 4 to 5 The procedure of Example 1 was repeated, except that the carrier used was alumina and the amount of methylaluminoxane and the amount of complex were changed. Was. The results are summarized in Table 1.

Example 6 The procedure of Example 1 was repeated, except that the carrier used was magnesia and the amount of methylaluminoxane and the amount of complex were changed. The results are summarized in Table 1.

Example 7 The procedure of Example 1 was repeated, except that the carrier used was boron oxide, and the amount of methylaluminoxane and the amount of complex were changed. .

The copolymers obtained in Examples 1 to 7
When the transparency was evaluated by press molding at ℃, it was found that all were excellent in transparency.

Comparative Example 1 The same procedure was carried out except that the complex used in Example 1 was changed to zirconocene dichloride, and the amount of methylaluminoxane and the amount of complex were changed.

Example 8 The supported catalyst obtained in Example 1 was stored for a long time in an ampoule of nitrogen atmosphere, and the change with time in the activity is shown in Table 2.

Comparative Example 2 The supported catalyst obtained in Comparative Example 1 was examined for changes over time in the same manner as in Example 8, and the results are shown in Table 2.

Example 9 The procedure of Example 1 was repeated, except that hydrogen was allowed to coexist during the polymerization of Example 1, and the MFR of the obtained polyethylene copolymer was 2.3.

[0026]

[Table 1]

[0027]

[Table 2]

[0028]

According to the present invention, an asymmetric metallocene compound is used as an olefin polymerization catalyst component, and is supported on an inorganic oxide and an organic aluminum component is used at the time of polymerization. An ethylene-α-olefin copolymer having a low molecular weight and a low melting point and a monomodal melting point is obtained, which means that the composition distribution of the copolymer is narrow.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hiroyuki Ohira, Oita, Oita City, Oita Prefecture, 2nd place, Showa Denko K.K. (56) References JP-A-5-209013 (JP, A) JP-A-5-148284 (JP, A) JP-A-5-208987 (JP, A) JP-A-3-1990 21607 (JP, A) JP-A-4-7306 (JP, A) British Patent Application Publication 2241244 (GB, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08F 4/60-4 / 70 CA (STN) REGISTRY (STN)

Claims (3)

(57) [Claims] (A) a metallocene represented by the general formula (1)
Compound 1[M in the formula (1) is a transition of any of Ti, Zr, and Hf.
Means metal. X¹And X^Two Are the same but different
Hydrogen, hydrocarbons having 1 to 10 carbon atoms
Meaning an alkyl group, an alkylsilyl group, or a halogen atom
I do. R¹ , R^Two , R^Three , R⁶ , R⁷ Is a hydrogen atom, charcoal
A hydrocarbon group having 1 to 10 atoms, an alkylsilyl group;
Means R¹ , R^Two One of them is a hydrogen atom
No. Also R^Four , R^Five Are bonded to each other to form an indenyl ring
Form.Y is a carbon atom or a silicon atom or
It means germanium atom. Where n is an integer from 1 to 3.
number〕and  (B) An organic aluminum oxy compound and (c) a solid catalyst component obtained by being supported on an inorganic oxide carrier
Using organic aluminum component as co-catalyst during polymerization
A copolymer of ethylene and an α-olefin, characterized in that
Production method. 2. The method for producing a copolymer of ethylene and α-olefin according to claim 1, wherein (b) is methylaluminoxane, and (c) is silica or alumina. 3. The method for producing a copolymer of ethylene and α-olefin according to claim 2, wherein the compound (c) is silica or alumina treated with an organoaluminum.