JP2668733B2 - Catalyst for polyolefin production - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a catalyst for producing a highly stereoregular polyolefin. More specifically, it relates to the catalyst comprising a novel hafnium compound having a bis-substituted cyclopentadienyl bridge type bidentate ligand having a bridge structure and aluminoxane.

[Prior art and its problems] As a homogeneous catalyst for olefin polymerization, a so-called Kaminski catalyst is well known. It is known that this catalyst system has a very high polymerization activity and, for example, in propylene polymerization, any of atactic polypropylene, isotactic polypropylene and syndiotactic polypropylene can be produced.
(Makrmol.Chem., Rapid Commun. 4, 417-421 (1983), An
gew.Chem.Int.Ed.Engl.24,507-508 (1985), J.Am.Che
m. Soc. 1987, 109, 6544-6545, J. Am. Chem. Soc. 1988, 110, 6
255-6256) The following compounds are known as transition metal compounds for producing isotactic polymers. Transition metal compounds having an ethylenebisindenyl ligand by Kaminsky et al. (JP-A-61-264,010, JP-A-64
-51,408, JP-A-64-66,216), R "by Yuen et al.
(C ₅ (R ′) ₄ ) ₂ MeQp-type metallocene compounds (JP-A-6
3-251,405, JP-A-63-295,607, JP-A-64-74,202)
It is.

Further, metallocene compounds for producing stereo block polymers are also known. (JP 63-142,004, JP 63
However, even if any of the hafnium-based catalysts described in the above literature is used in propylene polymerization, there is a problem that the melting point of the obtained polymer is low.

The present inventors have conducted studies to solve the above problems, and as a result, succeeded in efficiently synthesizing the above-mentioned novel hafnium compound, and furthermore, the catalyst system comprising these compounds and aluminoxane has a melting point of The present inventors have found that a highly stereoregular polyolefin can be produced, and have arrived at the present invention based on this finding.

[Means for Solving the Problems] That is, the present invention provides (A) a hafnium compound represented by the general formula [I]: (However, Y represents silicon or germanium. ▲ R ¹ _n
▼ -C ₅ H _4-n and ▲ R ¹ _q ▼ -C ₅ H _4-q represent a substituted cyclopentadienyl group, and n and q are integers of 1 to 3. each
R ^{1 s} may be the same as or different from each other and represent hydrogen, a silyl group or a hydrocarbon group, but the position and type of R ¹ on the cyclopentadienyl ring are such that a symmetry plane including Hf does not exist. I shall. Further, in at least one of the cyclopentadienyl rings, R ¹ is present on at least one carbon next to the carbon bonded to Y. each
R ^{2 s} may be the same as or different from each other and represent hydrogen or a hydrocarbon group. Further, x may be the same or different and represents hydrogen, halogen or a hydrocarbon group. ) And (B) general formula [II] or general formula [III] (However, m is a number of 4 to 60, and R ³ is a hydrocarbon group.)
The present invention relates to a catalyst for producing a highly stereoregular polyolefin containing an aluminoxane as an active ingredient.

The catalyst component hafnium compound (A) used in the method of the present invention is a novel hafnium compound having a bis-substituted cyclopentadienyl bridge type bidentate ligand having a bridged structure. Y is silicon or germanium. The number of substituents on the two cyclopentadienyl rings may be any of 1 to 3 substituents. Each R ¹
Or different are identical to one another, hydrogen, a silyl group or a hydrocarbon group (an alkyl having 1 to 20 carbon atoms, alkenyl, aryl, alkylaryl, arylalkyl, etc.) show, the R ¹ cyclopenta Positions and types on the dienyl ring are arranged so that no symmetry plane including Hf exists. Further, in at least one of the cyclopentadienyl rings, R ¹ is present on at least one carbon next to the carbon bonded to Y. Examples of the silyl group include a trimethylsilyl group, a triethylsilyl group, and a triphenylsilyl group.
Examples of hydrocarbon groups include methyl, ethyl, propyl, isopropyl, butyl, sec-butyl, ter
t-butyl group, phenyl group, tolyl group, biphenyl group,
Examples include a naphthyl group. Each R ² may be the same or different and is hydrogen or the above-mentioned hydrocarbon group. X is hydrogen, halogen such as fluorine, chlorine, bromine, iodine, or the above hydrocarbon group.

A typical synthetic route for the compound [1] of the present invention is n = q =
Taking 2 as an example, it can be abbreviated as follows, but is not limited thereto.

Non-limiting examples of the hafnium compound include dimethylsilyl (methylcyclopentadienyl) (2,4-dimethylcyclopentadienyl) hafnium chloride, dimethylsilyl (methylcyclopentadienyl) (2,3,5-
Trimethylcyclopentadienyl) hafnium dichloride, dimethylsilylbis (2,4-dimethylcyclopentadienyl) hafnium dichloride, diphenylsilylbis (2,4-dimethylcyclopentadienyl) hafnium dichloride, dimethylsilylbis (2,4 -Dimethylcyclopentadienyl) hafnium dibromide, dimethylsilylbis (2,4-dimethylcyclopentadienyl) hafnium dimethyl, dimethylsilyl (2,4-dimethylcyclopentadienyl) (2,3,5-trimethylcyclo Pentadienyl) hafnium dichloride, dimethylsilylbis (2,3,5-trimethylcyclopentadienyl) hafnium dichloride, dimethylgermyl (methylcyclopentadienyl) (2,4-dimethylcyclopentadienyl) hafnium dichloride, Dimethyl germi (Methylcyclopentadienyl) (2,3,5-trimethylcyclopentadienyl) hafnium dichloride, dimethylgermylbis (2,4-dimethylcyclopentadienyl) hafnium dichloride, dimethylgermyl (2,4- Examples thereof include dimethylcyclopentadienyl) (2,3,5-trimethylcyclopentadienyl) hafnium dichloride and dimethylgermylbis (2,3,5-trimethylcyclopentadienyl) hafnium dichloride.

In the method of the present invention, another catalyst constituent aluminoxane (B) that can be used is a compound represented by the general formula [II] or the general formula [III]: Is an organoaluminum compound represented by R ³ is a hydrocarbon group such as a methyl group, an ethyl group, a propyl group, and a butyl group, and is preferably a methyl group or an ethyl group. m
Is an integer of 4 to 60, preferably 6 or more, and especially
It is preferably 10 or more. Processes for producing compounds of this type are known. For example, trialkyl is added to a hydrocarbon medium suspension of a compound containing adsorbed water or a salt containing water of crystallization (eg, copper sulfate hydrate, aluminum sulfate hydrate). A method of reacting by adding aluminum can be exemplified.

In the method of the present invention, the olefin used for the polymerization reaction is propylene, 1-butene, 4-methyl-1-pentene, 1-hexene, 1-octene, 1-decene,
-Dodecene, 1-tetradecene, 1-hexadecene, 1
Α-olefins such as -octadecene and 1-eicosene, and a mixture of two or more of these can be used for polymerization. Copolymerization of the above α-olefins with ethylene is also possible. Furthermore, butadiene, 1,4-hexadiene, 1,4-pentadiene, 1,7-octadiene, 1,8-
It is also effective for copolymerization with conjugated and non-conjugated dienes such as nonadiene and 1,9-decadiene, or with styrene or cyclic olefins such as cyclopropane, cyclobutene, cycloxene, norbornene and dicyclopentadiene.

The polymerization method used in the present invention can be either liquid phase polymerization or gas phase polymerization. The liquid phase polymerization solvent is a hydrocarbon compound capable of dissolving both components (A) and (B), such as benzene, toluene, o-xylene,
Aromatic hydrocarbons such as p-xylene, ethylbenzene, butylbenzene, mesitylene, and naphthalene are used, and toluene and xylene are preferable. further,
Polymerization can be carried out by prepolymerization in an aromatic hydrocarbon even in a solvent in which both components (A) and (B) cannot be dissolved. Such solvents include butane, isobutane,
Aliphatic hydrocarbons such as pentane, hexane, octane, decane, dodecane, hexadecane and octadecane, alicyclic hydrocarbons such as cyclopentane, methylcyclopentane, cyclohexane and cyclooctane, petroleum fractions such as gasoline, kerosene and diesel oil It is a good thing. Of these, aliphatic hydrocarbons are preferred. Moreover,
It is also possible to use liquefied olefin itself such as liquefied propylene and liquefied butene-1 as a solvent.

As the catalyst component, a mixture of both components (A) hafnium compound and (B) aluminoxane may be supplied to the reaction system in advance, or both components (A) and (B) may be supplied to the reaction system. Good. In any case, the concentration of both components in the polymerization system, the molar ratio is not particularly limited, preferably hafnium concentration 10 ^-3 ~ 10 ^-10 mol /
The molar ratio of Al / hafnium atoms is preferably 100 or more, particularly 1000 or more. The olefin pressure of the reaction system is not particularly limited, but is preferably atmospheric pressure to
It is in the range of 50 kg / cm ² G and the polymerization temperature is not limited, but is usually in the range of -50 to 230 ° C, preferably in the range of -30 to 100 ° C. The molecular weight at the time of polymerization can be adjusted by known means, for example, by setting the temperature or introducing hydrogen.

[Effect of the Invention] As a novel hafnium compound to be combined with aluminoxane, if the catalyst of the present invention using a hafnium compound having a bis-substituted cyclopentadienyl bridge type bidentate ligand having a bridged structure is used, a high melting point can be obtained. Stereoregular polymers can be produced.

[Examples] Next, the present invention will be specifically described with reference to Examples.

Example 1 "Dimethylsilylbis (2,4-dimethylcyclopentadienyl) hafnium dichloride" All reactions were carried out under an inert gas atmosphere. Also,
The reaction solvent used was previously dried. 200ml
In a glass reaction vessel prepared in 1., dissolve 3.79 g (15.5 mmol) of dimethylbis (2,4-dimethylcyclopentadienyl) silane in 50 ml of tetrahydrofuran, and slowly add 25 ml of 1.49M hexane solution of n-betyllithium under ice cooling. And dripped. After stirring for 4 hours at room temperature, a yellow suspension (Li
₂ [Me ₂ Si (Me ₂ -C ₅ H ₂ ) ₂ ) was obtained.

Hafnium tetrachloride 4.9 in a 500 ml glass reaction vessel
6 g (15.5 mmol) was cooled to -78 ° C and 200 ml of tetrapidrofuran was added. Next, the above yellow suspension was cooled to -65 ° C.
And slowly dripped. After slowly returning to room temperature, the mixture was stirred at room temperature for 24 hours. The solvent was distilled off from the yellow solution containing a slight amount of white precipitate, 300 ml of methylene chloride was added, and the white solid formed was removed by filtration. The obtained yellow filtrate was concentrated, pentane was added, and the generated solid was filtered to obtain a yellow-white solid. Recrystallization was performed with a toluene-hexane mixed solvent to obtain 0.96 g of white crystals.

Example 2 [Polymerization] Purified toluene (500 ml), methylaluminoxane (molecular weight 930) 3.3 mmol, and dimethylsilylbis (2,4-dimethyl) manufactured by Toyo Stoufer Chemical Co. 0.005 mmol of (cyclopentadienyl) hafnium dichloride were sequentially added, and the temperature was raised to 30 ° C. Then, propylene was continuously introduced into the mixture so that the total pressure was maintained at 3 kg / cm ² G,
Polymerization was carried out for hours. After the reaction, the catalyst component was decomposed with methanol, and the obtained polypropylene was dried. As a result, 1.9 g of isotactic polypropylene was obtained. The catalytic activity was 1.1 kg / gHf · hr. The molecular weight of the polymer was 147,500 and the melting point was 160.9 ° C.

Example 3 "Dimethylsilylbis (2,3,5-trimethylcyclopentadiethyl) hafnium dichloride" All reactions were carried out under an inert gas atmosphere. The reaction solvent used was dried in advance. 2.64 g (9.7 mmol) of dimethylbis (2,3,5-trimethylcyclopentadiethyl) silane through a 200 ml glass reaction vessel
Was dissolved in 50 ml of tetrahydrofuran, and 16 ml of a 1.49M hexane solution of n-betyllithium was slowly added dropwise under ice cooling. After stirring for 12 hours at room temperature, a white suspension (Li ₂ [M
e ₂ to give Si and _{(Me 3 -C 5 H) 2} ).

Hafnium tetrachloride 3.1 in a 500 ml glass reaction vessel
g (9.7 mmol) was cooled to -78 ° C and 200 ml of tetrahydrofuran were added. Next, the white suspension was slowly added dropwise at -78 ° C. After slowly returning to room temperature, the mixture was stirred at room temperature for 48 hours. The solvent was distilled off from the pale yellow solution, 300 ml of methylene chloride was added, and the formed white solid was removed by filtration. The obtained pale yellow filtrate was concentrated, pentane was added, and the generated solid was filtered to obtain a white solid. It was extracted with hot hexane, concentrated to dryness to obtain a white solid, and further recrystallized with hexane to obtain 0.16 g of a white crystal.

Example 4 [Polymerization] 500 ml of purified toluene, 3.3 mmol of methylaluminoxane (molecular weight 930) manufactured by Toyo Stoufer Chemical Co., Ltd., and dimethylsilylbis (2,3,5) were placed in a 1.5 L internal autoclave made of SUS that had been sufficiently replaced with nitrogen. 0.005 mmol of -trimethylcyclopentadienyl) hafnium dichloride were sequentially added, and the temperature was raised to 30 ° C. Then, propylene was continuously introduced into the mixture so that the total pressure was maintained at 3 kg / cm ² G, and polymerization was performed for 2 hours. After the reaction, the catalyst component was decomposed with methanol, and the obtained polypropylene was dried.
As a result, isotactic polypropylene 3.0 was obtained. The catalytic activity was 1.7 kg / gHf · hr. The molecular weight of the polymer was 260,000 and the melting point was 162.8 ° C.

Comparative Example 1 Purified toluene (500 ml), Toyo Stouffer Chemical Co., Ltd. methylaluminoxane (molecular weight: 930) 3.3 mmol and ethylenebis (indenyl) hafnium dichloride 0.005 mmol were sequentially added to a 1.5-liter SUS autoclave sufficiently purged with nitrogen. Then, the temperature was raised to 30 ° C. Then, propylene was continuously introduced into the mixture so that the total pressure was maintained at 3 kg / cm ² G, and polymerization was performed for 2 hours. After the reaction, the catalyst component was decomposed with methanol, and the obtained polypropylene was dried. As a result, 21 g of isotactic polypropylene was obtained. The catalytic activity was 12 kg / gHf · hr.
The molecular weight of the polymer is 256,000 and the melting point is 137.5.
° C.

[Brief description of the drawings]

FIG. 1 is a process chart (flow sheet) for producing a polyolefin using the catalyst of the present invention.

Claims (3)

(57) [Claims] 1. A hafnium compound represented by the general formula [I]: (However, Y represents silicon or germanium. ▲ R
¹ _n ▼ -C ₅ H _4-n and ▲ R ¹ _q ▼ -C ₅ H _4-q represent a substituted cyclopentadienyl group, and n and q are integers of 1 to 3. Each R ¹ may be the same or different from each other, hydrogen,
A silyl group or a hydrocarbon group is shown, but the position and type of R ¹ on the cyclopentadienyl ring are assumed to be the positions where there is no symmetry plane containing Hf. Further, in at least one of the cyclopentadienyl rings, R ¹ is present on at least one carbon next to the carbon bonded to Y. Each R ² may be the same as or different from each other and represents hydrogen or a hydrocarbon group. X may be the same or different and represents a hydrogen, a halogen or a hydrocarbon group. ) And (B) general formula [II] or general formula [III] (However, m is a number of 4 to 60, and R ³ is a hydrocarbon group.)
A catalyst for producing an isotactic olefin polymer, comprising an aluminoxane represented by the following formula: 2. The transition metal compound represented by the general formula [I], wherein n and q are integers of 1 to 3,
The catalyst for producing an isotactic olefin polymer according to claim 1, wherein a transition metal compound which does not take the value of is used. 3. The isotactic olefin polymer according to claim 1, wherein a transition metal compound in which n and q are integers of 2 to 3 is used as the transition metal compound represented by the general formula [I]. Production catalyst.