JPH08217816A - Production of stereospecific polypropylene - Google Patents

Abstract

PURPOSE: To produce stereospecific polypropylene excellent in particle characteristics, capable of efficiently obtaining syndiotactic polypropylene excellent in particle characteristics and mold processing when applied especially to a production of syndiotactic polypropylene. CONSTITUTION: This method for producing stereospecific polypropylene comprises polymerizing propylene in the presence of a catalyst comprising (A) a methallocene compound capable of producing stereospecific polypropylene, (B) a solid catalyst component formed from aluminoxane and a fine particle carrier and, if needed, (C) an organoaluminum compound. Ethylene is prepolymerized in an inert solvent in the presence of the catalyst comprising the component (A), (B) and, if needed, (C) and propylene is successively polymerized.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing stereoregular polypropylene. Specifically, it relates to a method for efficiently producing stereoregular polypropylene having excellent particle properties. Furthermore, when the method of the present invention is applied to the production of syndiotactic polypropylene, it is possible to produce syndiotactic polypropylene having excellent particle properties and molding processability.

[0002]

2. Description of the Related Art In recent years, a transition metal compound having a cyclopentadienyl group, an indenyl group, a fluorenyl group, or a substitution product thereof, a so-called metallocene compound, has been considered useful as a catalyst component for polyolefin production.

Japanese Patent Application Laid-Open No. 61-130314 describes a method for producing a polyolefin using a catalyst composed of a sterically fixed zircon chelate compound and an aluminoxane. Further, the publication describes a method for producing a polyolefin having a high isotacticity by using ethylene-bis (4,5,6,7-tetrahydro-1-indenyl) zirconium dichloride as a transition metal compound. There is. JP-A-64-
In Japanese Patent No. 66124 and Japanese Patent Laid-Open No. 3-12406,
There is disclosed a stereoregular olefin polymerization catalyst containing a transition metal compound having a silicon-crosslinked cyclopentadienyl compound as a ligand and an aluminoxane as an active ingredient.

Japanese Unexamined Patent Publication Nos. 2-41303 and 2-
JP-A-274703 and JP-A-2-274704 describe that a syndiotactic poly-α-olefin can be produced by using a catalyst composed of a metallocene compound having an asymmetric cross-linking ligand and an aluminoxane. There is.

Since the metallocene-based catalysts as described above are generally soluble in a solvent, when the solvent polymerization or the gas phase polymerization is attempted, the produced polymer is inferior in the powder property, or is not transferred to a polymerization machine. There was a problem such as sticking to the wall.

In order to solve these problems, Japanese Patent Laid-Open No.
1-108610, JP-A-63-66206, JP-A-2-17104 and the like propose a method of polymerizing an olefin using a solid catalyst in which a metallocene compound and an aluminoxane are supported on a fine particle carrier. ing.

On the other hand, the molded product obtained from syndiotactic polypropylene is superior in transparency, gloss and flexibility to the molded product obtained from the conventional isotactic polypropylene, and its use as a new polypropylene is expected. ing. However, syndiotactic polypropylene has a problem that it is inferior in moldability because it has a slower crystallization rate than isotactic polypropylene.

[0008]

The method for producing a polyolefin by polymerizing an olefin in the presence of a solid catalyst in which a metallocene compound and an aluminoxane are supported on a fine particle carrier as described above, has some excellent powder properties. Although it is possible to produce a polyolefin, when a stereoregular polypropylene is produced by these methods, fine powder and the like are produced, which is still insufficient for industrial application.

[0009]

[Means for Solving the Problems] The inventors of the present invention have solved the problems described above and have made diligent studies on a method of producing stereoregular polypropylene having excellent powder properties. As a result, after prepolymerization using a specific monomer, The inventors have found that the above-mentioned object can be achieved by polymerizing propylene, and have completed the present invention. That is, the present invention comprises (A) a metallocene compound capable of producing stereoregular polypropylene, (B) a solid catalyst component formed from an aluminoxane and a fine particle carrier, and (C) an organoaluminum compound if necessary. In a method for producing stereoregular polypropylene by polymerizing propylene in the presence of a catalyst, in the presence of a catalyst comprising the above (A), (B) and, if necessary, (C) in an inert solvent, This is a method for producing stereoregular polypropylene, which comprises preliminarily polymerizing with ethylene and then polymerizing propylene.

The metallocene compound capable of producing the stereoregular polypropylene used as the component (A) in the method of the present invention is a metallocene compound capable of producing isotactic or syndiotactic polypropylene.

As the metallocene compound which can be used to produce isotactic polypropylene, for example, Japanese Patent Laid-Open No.
1-130314, JP 3-12406 A, JP 3-197516 A and Angew. Chem.
Int. Ed. Eng., 31 , 1347 (1992), Organometallics, 13 , 9
54 (1994) and the like, and metallocene compounds having a transition metal such as titanium, zirconium and hafnium. Among these, metallocene compounds containing zirconium and hafnium are preferably used. Specific examples of such metallocene compounds include, for example, ethylenebisindenyl zirconium dichloride,
Ethylene bis (tetrahydroindenyl) zirconium dichloride, dimethylsilylene bis (dimethylcyclopentadienyl) zirconium dichloride, dimethylsilylene bis (trimethylcyclopentadienyl) zirconium dichloride, dimethylsilylene bis (indenyl)
Zirconium dichloride, dimethyl silylene bis (2-
Examples thereof include methylindenyl) zirconium dichloride and dimethylsilylenebis (2-methyl-4-isopropylindenyl) zirconium dichloride.

Examples of metallocene compounds which can be used to produce syndiotactic polypropylene include, for example, JP-A-2-41303, JP-A-2-274703, JP-A-2-274704, and JP-A-4-69.
The metallocene compounds described in Japanese Patent No. 394, etc. can be mentioned. Specific examples of such metallocene compounds include, for example, isopropylidene (cyclopentadienyl) (9-fluorenyl) zirconium dichloride, cyclohexylidene (cyclopentadienyl) (9
-Fluorenyl) zirconium dichloride, diphenylmethylene (cyclopentadienyl) (9-fluorenyl) zirconium dichloride, methylphenylmethylene (cyclopentadienyl) (9-fluorenyl) zirconium dichloride, isopropylidene (cyclopentadienyl) (2, 7-di-t-butyl-9-fluorenyl)
Zirconium dichloride, cyclohexylidene (cyclopentadienyl) (2,7-dit-butyl-9-fluorenyl) zirconium dichloride, diphenylmethylene (cyclopentadienyl) (2,7-dit-butyl-9)
-Fluorenyl) zirconium dichloride, methylphenylmethylene (cyclopentadienyl) (2,7-dit
-Butyl-9-fluorenyl) zirconium dichloride and the like can be mentioned.

The aluminoxane used for forming the solid catalyst of the component (B) in the present invention is, for example, JP-A-59-95292 and JP-A-58-1930.
A reaction product of a trialkylaluminum and water as described in Japanese Patent No. 9 is utilized. Methylaluminoxane, which is a reaction product of trimethylaluminum and water, is preferably used. In addition,
JP-A-2-24701 and JP-A-3-103407.
Aluminoxane having two or more kinds of alkyl groups described in JP-A No. 63-198691, fine-particle aluminoxane described in JP-A No. 63-198691, and JP-A No. 2-167302. An aluminum oxy compound obtained by contacting aluminoxane with water or an active hydrogen compound can also be preferably used. The aluminoxane may be mixed with some alkylaluminum.

As the fine particle carrier, a metal chloride such as magnesium chloride, a metal oxide such as silica gel or alumina, or a composite thereof is used. Silica gel is preferably used because it can firmly and efficiently support aluminoxane. More preferably, silica gel having a surface area of 400 m ² / g or more is used. These fine particle carriers are usually dehydrated and used by a method such as firing. The particle diameter of the fine particle carrier is in the range of 0.01 to 1000 μm, usually 0.1 to 10
It is in the range of 0 μm.

As the method for producing the solid catalyst of the component (B) in the present invention, a method of contacting the aluminoxane with the fine particle carrier in a solvent or a non-solvent can be used, and preferably the aluminoxane in a solvent is used. The method of contacting the fine particles with the fine particle carrier is adopted. The solvent used can be used without limitation as long as it is inert to aluminoxane, and specifically, for example, aromatic hydrocarbons such as benzene, toluene, xylene and pentane, hexane, heptane, and fats such as octane. Group hydrocarbons may be mentioned. The contact temperature is -50 to 5
It is in the range of 00 ° C, usually in the range of 0 to 200 ° C. The use ratio of aluminoxane to the particulate carrier is
It is 0.01 to 100 times by weight, preferably 0.1 to 10 times by weight.

In the present invention, in addition to the above-mentioned components (A) and (B), an organoaluminum compound is optionally used as a component (C) for the purpose of poisoning in the polymerization system or as an activity improver. You can also Specific examples of the organoaluminum compound used as the component (C) include trimethylaluminum, triethylaluminum, triisobutylaluminum, tri-n-octylaluminum and the like. Preferred are triethyl aluminum and triisobutyl aluminum. The organoaluminum compound may be added to either one or both systems during the prepolymerization and the main polymerization in the present invention.

When the component (C) is used in combination, the amount used is 1 with respect to the metallocene compound as the component (A).
It is 10000 times by mole, usually 10 to 1000 times by mole.

The feature of the present invention is that the catalyst comprising the above-mentioned components (A), (B) and, if necessary, the component (C) is prepolymerized in advance with ethylene in an inert solvent, and then with propylene. To polymerize. By doing so,
It is possible to obtain polypropylene having excellent powder properties.

When the method of the present invention is applied to the production of syndiotactic polypropylene, it is possible to obtain syndiotactic polypropylene having a high crystallization rate and excellent moldability.

The prepolymerization of ethylene in the method of the present invention is carried out in an inert solvent in the temperature range of -100 to 100 ° C, preferably -50 to 80 ° C. The polymerization amount of ethylene is 0.001 to 100 times by weight, preferably 0.01 to 5 times the solid catalyst which is the component (B).
It is 0 times the weight.

There are no particular restrictions on the polymerization method and polymerization conditions for propylene, which is the main polymerization in the method of the present invention, and known methods used in the polymerization of olefins can be used.
A solvent polymerization method using an inert hydrocarbon medium, a bulk polymerization method in which substantially no inert hydrocarbon medium is present, or a gas phase polymerization method can also be used, and the polymerization temperature is −100 to 200.
It is general to carry out the polymerization at a pressure of from atmospheric pressure to 100 kg / cm ² as a polymerization pressure. The pressure is preferably −50 to 100 ° C. and atmospheric pressure to 50 kg / cm ² .

Examples of the hydrocarbon medium used in the treatment or prepolymerization of the catalyst component or in the main polymerization include aliphatic hydrocarbons such as butane, pentane, hexane, heptane, octane, nonane, decane, cyclopentane and cyclohexane. In addition, aromatic hydrocarbons such as benzene, toluene and xylene can also be used.

In the present invention, not only homopolymerization of propylene but also the performance as stereoregular polypropylene is not impaired, for example, ethylene, 1-butene, 1-hexene, 1-octene and the like having about 2 to 25 carbon atoms. It can also be used in the production of ethylene or α-olefin copolymers.

[0024]

EXAMPLES The present invention will be specifically described below with reference to examples.

[0025] Example 1 silica gel was calcined at 200 ° C. in a glass flask 1 dm ³ was thoroughly purged with nitrogen Preparation of solid catalyst component] (Fuji Silysia Chemical Ltd., surface area 485m ² / g, pore volume 0.72 ml / g, average particle size 32 μm) 100 g were suspended in 300 cm ³ of toluene. To this suspension was added 400 cm ³ of a 20 wt% toluene solution of methylaluminoxane (manufactured by Tosoh Akzo, degree of polymerization 17), and the mixture was refluxed for 6 minutes.
Allowed to react for hours. 165 by distilling off the solvent under reduced pressure
g of solid catalyst component was obtained.

[0026] After sufficiently purged with nitrogen stainless steel autoclave Ethylene prepolymerization] internal volume 1 dm ^3, the solid catalyst component was heptane 0.5 dm ³ and the preparation 1.
Charged 5 g. Then, 25 mg of diphenylmethylene (cyclopentadienyl) fluorenyl zirconium dichloride and 1.25 g of triisobutylaluminum synthesized by the method described in JP-A-2-274703.
After charging, 7.5 g of ethylene gas was added and prepolymerization with ethylene was carried out at 20 ° C. for 1 hour. The amount of prepolymerization per 1 g of the solid catalyst component was 4.4 g. The prepolymerized slurry thus obtained was used for the following propylene main polymerization.

[Propylene Main Polymerization] A stainless autoclave having an internal volume of 5 dm ³ was sufficiently replaced with nitrogen, and the ethylene prepolymerized slurry obtained above was charged as solid catalyst components in an amount of 60 mg and 50 mg of triisobutylaluminum. After adding 1.5 kg of liquid propylene and 3.25 dm ^{3 of} hydrogen (standard state), the temperature was raised to 60 ° C. and polymerization was carried out at that temperature for 1 hour, resulting in 614 g.
A syndiotactic polypropylene of was obtained. The intrinsic viscosity (hereinafter abbreviated as [η]) of the obtained syndiotactic polypropylene in a tetralin solution at 135 ° C. was 1.25 dl / g, and differential scanning calorimetry (DS
The melting point (Tm) measured by C) was 133 ° C., and the isothermal semi-crystallization rate (T _1/2 ) measured at 85 ° C. was 156 seconds. The bulk density of the powder was 0.38 g / ml, and no fine powder passed through the 200-mesh sieve.

Comparative Example 1 60 mg of the solid catalyst component obtained in the preparation of the solid catalyst component of Example 1, 1 mg of diphenylmethylene (cyclopentadienyl) fluorenylzirconium dichloride and 100 mg of triisobutylaluminum were prepolymerized with ethylene. Example 1 except that it was used as it was without treatment
Polymerization of propylene was carried out in the same manner as the main polymerization of propylene. As a result, 578 g of syndiotactic polypropylene powder was obtained. The powder [η] is 1.2
7 dl / g, Tm is 132 ℃, T _1/2 was 234 seconds. The bulk density of the powder was 0.35 g / ml, and a small amount of fine powder passing through a 200-mesh sieve was observed.

Example 2 [Ethylene prepolymerization] The fed ethylene gas amount was 2
Prepolymerization of ethylene was carried out in the same manner as in the ethylene prepolymerization of Example 1 except that the amount was 1 g. as a result,
A prepolymerized slurry having a prepolymerization amount of 12.8 g per 1 g of the solid catalyst component was obtained.

[Propylene Main Polymerization] Propylene was polymerized in the same manner as in the propylene main polymerization of Example 1 except that the preliminarily polymerized slurry obtained above was used. As a result, 702 g of syndiotactic polypropylene powder was obtained. The powder [η] was 1.23 dl / g, Tm was 131 ° C., and T _1/2 was 108 seconds. The bulk density of the powder was 0.35 g / ml, and no fine powder that could pass through a 200-mesh sieve was found.

[0031]

By carrying out the method of the present invention, stereoregular polypropylene having excellent particle properties can be produced. Further, particularly when the method of the present invention is applied to the production of syndiotactic polypropylene, it is possible to efficiently obtain syndiotactic polypropylene excellent in particle properties and molding processability, which is extremely valuable industrially. .

Claims (2)

[Claims] 1. A metallocene compound capable of producing stereoregular polypropylene (A), a solid catalyst component (B) formed from an aluminoxane and a fine particle carrier, and optionally (C) an organoaluminum compound. In a method for producing stereoregular polypropylene by polymerizing propylene in the presence of a catalyst, in the presence of a catalyst comprising the above (A), (B) and, if necessary, (C) in an inert solvent, A method for producing stereoregular polypropylene, which comprises preliminarily polymerizing with ethylene and then polymerizing propylene. 2. The method for producing stereoregular polypropylene according to claim 1, wherein the stereoregular polypropylene is syndiotactic polypropylene.