JPH1112310A - Polymerization of propylene - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effect continuous propylene polymerization in high yield by using a homogeneous catalyst in the polymerization system comprising a plurality of polymerization zones, effecting the polymerization in a specific amount at a specific temperature in the first polymerization area filled with liquid propylene without vapor-phase space followed by the remaining polymerization over the specific temperature under the condition that there is vapor phases. SOLUTION: In a polymerization system comprising 2 or more polymerization areas, a homogeneous catalyst comprising a transition metal compound component [as ethylenebis(indenyl)zirconium dichloride, etc.], and an organometallic compound is used to polymerize less then 1/5 of the whole polymerization amount in the first polymerization area, as the propylene itself is used as a liquid medium at a temperature more than 10 deg.C lower the maximum polymerization temperature at the later polymerization area which is filled with the liquid phase without the vapor phase space. Then, the remaining polymerization is carried out under the condition that there is the vapor phase space at 60 deg.C or higher in the at least one of the following polymerization areas to obtain continuously polypropylene in high yield.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for polymerizing propylene. More specifically, it relates to a method for continuously polymerizing propylene using a homogeneous catalyst under specific polymerization conditions.

[0002]

2. Description of the Related Art As a method of polymerizing propylene using a homogeneous catalyst, it is the first to disclose a method of polymerizing propylene using zirconocene and methylaluminoxane.
Recently, it has been reported that a crystalline polypropylene such as isotactic and syndiotactic polypropylene can be obtained by using a metallocene compound having a ligand to which two cyclopentadienyl groups or derivatives thereof are bonded. (Japanese Rubber Association Journal Vol. 69 No. 3 16
1). The use of these homogeneous catalysts provides a polymer which is compositionally uniform and has a relatively narrow molecular weight distribution, so that unprecedented physical properties are expected.

[0003]

When a homogeneous catalyst is used, a polypropylene having a uniform composition and physical properties such as rigidity equivalent to that of a conventional Ziegler catalyst and having a relatively low melting point can be obtained. When the polymerization is carried out, there is a problem that the catalyst charging nozzle is closed or the polymer adheres to the reactor.

Therefore, the present invention uses a homogeneous catalyst,
An object of the present invention is to provide a method for stably and continuously polymerizing propylene with a high yield per catalyst.

[0005]

Means for Solving the Problems The present inventors have diligently studied a method for efficiently producing polypropylene by solving the above problems and completed the present invention.

[0006] That is, the propylene polymerization method of the present invention is a method of continuously polymerizing propylene using a homogeneous catalyst and propylene itself as a liquid medium in a polymerization system comprising at least two or more polymerization zones. In the polymerization zone, polymerization of 1/5 or less of the total polymerization amount is carried out at a temperature lower than the highest polymerization temperature of the subsequent polymerization zone by 10 ° C. or more and in a liquid-full state in which no gas phase is present, Below, the remaining polymerization is carried out in at least one subsequent polymerization zone.
The process is performed at 0 ° C. or higher.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, polymerization is carried out by a bulk polymerization method using propylene itself as a liquid medium. The bulk polymerization method is preferable because an expensive homogeneous catalyst having a high monomer concentration can be effectively used.

In the polymerization of propylene using a homogeneous catalyst, the activation energy is relatively large and it is preferable to polymerize at a high temperature. However, as the monomer concentration, the most effective bulk polymerization method uses two or more polymerization tanks. If the polymerization is not carried out so that the pressure becomes higher in the former stage when the polymerization is carried out, it is difficult to transfer the slurry. Therefore, it is necessary to increase the polymerization temperature of the polymerization tank in which the catalyst is charged, but under such conditions, there is a problem that the catalyst charging nozzle is blocked. In contrast, in the present invention, such a problem is solved by first polymerizing at a relatively low temperature.

In the present invention, the catalyst is charged into a first polymerization zone set at a temperature lower by at least 10 ° C. than the temperature of the polymerization zone in which many subsequent polymerizations are carried out, specifically, at 10 to 60 ° C. The polymerization in this polymerization zone is relatively small, specifically 1/5 or less of the polymerization amount to be polymerized in the whole polymerization system, preferably 1/1000 to 1/10 of the total polymerization amount, particularly preferably 1/100.
It is preferable to set it to about 500 to 1/20. In addition, the catalyst to be charged into the polymerization zone is previously 0.1% per solid catalyst component.
It is more preferable that propylene is polymerized from 100 g / g to 100 g / g. If this process is not performed, the bulk specific gravity may decrease. The polymerization in this polymerization zone is carried out at a lower temperature than the latter polymerization zone, and furthermore, this polymerization zone is filled with no gaseous phase, and the pressure is kept higher than that of the latter stage for transfer to the latter stage. . In at least a portion of the polymerization zone where a uniform catalyst is introduced, the linear velocity of propylene is preferably 2.0 m / sec or more, particularly preferably 4.0 m / sec or more. As an embodiment of the polymerization zone satisfying such conditions, Is a tank reactor or a ring reactor in a full state, and is preferably a ring reactor having ordinary pipes connected in a ring and having a pump for circulating a slurry therein. A polymer slurry having a shape capable of increasing the pressure of a polymerization slurry having an active catalyst as disclosed in JP-A-49281 is preferably used. If the linear velocity of the catalyst insertion portion is low, the nozzle may be blocked, which is not preferable.

In the present invention, it is preferable to control the molecular weight of the polymer obtained with hydrogen even in the first polymerization zone in which polymerization is carried out in a full state. In order to make the hydrogen concentration uniform, propylene in which predetermined hydrogen is dissolved in advance is preferably used. Is preferred in terms of operability and uniformity of polymerization.

In the present invention, the polymerization in the subsequent polymerization zone connected to the first polymerization zone is preferably carried out at a temperature as high as possible. In at least one polymerization zone, the polymerization is carried out at 60 ° C. or higher. This is because, as described above, in the polymerization of propylene using a homogeneous catalyst, it is preferable to carry out the polymerization at a higher temperature because the amount of polypropylene produced per catalyst is large. The polymerization temperature is 60 ° C. or higher, preferably 60 to 90 ° C.

As the homogeneous catalyst used in the present invention, various catalysts are exemplified. The catalyst is basically composed of a transition metal compound component and an organometallic component. It is preferable to use a metallocene compound as the transition metal compound component because crystalline polypropylene is obtained. Examples of these include isopropylidene (cyclopentadienyl-fluorenyl) zirconium dichloride, isopropylidene (cyclopentadienyl-indenyl) zirconium dichloride, isopropylidene (cyclopentadienyl-
2,7-di-t-butylfluorenyl) zirconium dichloride, isopropylidene (cyclopentadienyl-
3-methylfluorenyl) zirconium dichloride, isopropylidene (cyclopentadienyl-4-methylfluorenyl) zirconium dichloride, isopropylidene (cyclopentadienyl-octahydrofluorenyl) zirconium dichloride, isopropylidene (methylcyclo Pentadienyl-fluorenyl) zirconium dichloride, isopropylidene (dimethylcyclopentadienyl-fluorenyl) zirconium dichloride, isopropylidene (tetramethylcyclopentadienyl-
Fluorenyl) zirconium dichloride or diphenylmethylene (cyclopentadienyl-fluorenyl)
Zirconium dichloride, diphenylmethylene (cyclopentadienyl-indenyl) zirconium dichloride, diphenylmethylene (cyclopentadienyl-2,
7-di-t-butylfluorenyl) zirconium dichloride, diphenylmethylene (cyclopentadienyl-3)
-Methylfluorenyl) zirconium dichloride, diphenylmethylene (cyclopentadienyl-4-methylfluorenyl) zirconium dichloride, diphenylmethylene (cyclopentadienyl-octahydrofluorenyl) zirconium dichloride, diphenylmethylene (methylcyclopentane) Dienyl-fluorenyl) zirconium dichloride, diphenylmethylene (dimethylcyclopentadienyl-fluorenyl) zirconium dichloride, diphenylmethylene (tetramethylcyclopentadienyl-fluorenyl) zirconium dichloride, or cyclohexylidene (cyclopentadienyl-fluorenyl) zirconium Dichloride, cyclohexylidene (cyclopentadienyl-indenyl) zirconium dichloride, cyclohexane Siliden (cyclopentadienyl-2,7-di-t-butylfluorenyl) zirconium dichloride, cyclohexylidene (cyclopentadienyl-3-methylfluorenyl) zirconium dichloride, cyclohexylidene (cyclopentadienyl) -4-
(Methylfluorenyl) zirconium dichloride, cyclohexylidene (cyclopentadienyl-octahydrofluorenyl) zirconium dichloride, cyclohexylidene (methylcyclopentadienyl-fluorenyl) zirconium dichloride, cyclohexylidene (dimethylcyclopentadienyl) -Fluorenyl) zirconium dichloride, cyclohexylidene (tetramethylcyclopentadienyl-fluorenyl) zirconium dichloride, or dimethylsilyl (cyclopentadienyl-fluorenyl) zirconium dichloride, dimethylsilyl (cyclopentadienyl-indenyl) zirconium dichloride, dimethyl Silyl (cyclopentadienyl-
2,7-di-t-butylfluorenyl) zirconium dichloride, dimethylsilyl (cyclopentadienyl-3)
-Methylfluorenyl) zirconium dichloride, dimethylsilyl (cyclopentadienyl-4-methylfluorenyl) zirconium dichloride, dimethylsilyl (cyclopentadienyl-octahydrofluorenyl) zirconium dichloride, dimethylsilyl (methylcyclopentane) Dienyl-fluorenyl) zirconium dichloride, dimethylsilyl (dimethylcyclopentadienyl-
Fluorenyl) zirconium dichloride, dimethylsilyl (tetramethylcyclopentadienyl-fluorenyl) zirconium dichloride, or isopropylidene (cyclopentadienyl-fluorenyl) zirconium dimethyl, isopropylidene (cyclopentadienyl-
Indenyl) zirconium dimethyl, isopropylidene (cyclopentadienyl-2,7-di-t-butylfluorenyl) zirconium dimethyl, cyclohexylidene (cyclopentadienyl-fluorenyl) zirconium dimethyl, cyclohexylidene (cyclopentadiene) Enyl-2,7-di-t-butylfluorenyl) zirconium dimethyl, dimethylsilyl (cyclopentadienyl-fluorenyl) zirconium dimethyl, dimethylsilyl (cyclopentadienyl-indenyl) zirconium dimethyl, dimethylsilyl (cyclopentadiyl) Enil-2,
7-di-t-butylfluorenyl) zirconium dimethyl and the like, and metallocene compounds in which zirconium of the above metallocene compound is replaced with titanium or hafnium.

Further, dimethylsilylbis (cyclopentadienyl) zirconium dichloride, dimethylsilylbis (tetramethylcyclopentadienyl) zirconium dichloride, dimethylsilylbis (methylcyclopentadienyl) zirconium dichloride, dimethylsilylbis (dimethylcyclodienyl) Pentadienyl) zirconium dichloride, dimethylsilyl (2,4-dimethylcyclopentadienyl) (3 ′, 5′-dimethylcyclopentadienyl) zirconium dichloride, dimethylsilyl (2,3,5-trimethylcyclopentadienyl) )
(2 ′, 4 ′, 5′-trimethylcyclopentadienyl) zirconium dichloride, dimethylsilylbis (t
-Butylcyclopentadienyl) zirconium dichloride, dimethylsilylbis (trimethylsilylcyclopentadienyl) zirconium dichloride, dimethylsilylbis (2-trimethylsilyl-4-t-butylcyclopentadienyl) zirconium dichloride, dimethylsilylbis (4 5,6,7-tetrahydro-indenyl)
Zirconium dichloride, dimethylsilylbis (indenyl) zirconium dichloride, dimethylsilylbis (2-methylindenyl) zirconium dichloride, dimethylsilylbis (2,4-dimethylindenyl) zirconium dichloride, dimethylsilylbis (2,4,7
-Trimethylindenyl) zirconium dichloride, dimethylsilylbis (2-methyl-4-phenylindenyl) zirconium dichloride, dimethylsilylbis (2
-Ethyl-4-phenylindenyl) zirconium dichloride, dimethylsilylbis (benz [e] indenyl) zirconium dichloride, dimethylsilylbis (2
-Methylbenz [e] indenyl) zirconium dichloride, dimethylsilylbis (3-methylbenz [e] indenyl) zirconium dichloride, dimethylsilylbis (benz [f] indenyl) zirconium dichloride, dimethylsilylbis (2-methylbenz [f] indenyl) Zirconium dichloride, dimethylsilylbis (3-methylbenz [f] indenyl) zirconium dichloride, dimethylsilylbis (cyclopenta [cd]
Indenyl) zirconium dichloride, dimethylsilylbis (cyclopentadienyl) zirconium dimethyl,
Dimethylsilylbis (tetramethylcyclopentadienyl) zirconium dimethyl, dimethylsilylbis (methylcyclopentadienyl) zirconium dimethyl, dimethylsilylbis (dimethylcyclopentadienyl) zirconium dimethyl, dimethylsilyl (2,4-dimethylcyclopenta Dienyl) (3 ', 5'-dimethylcyclopentadienyl) zirconium dimethyl, dimethylsilyl (2,3,5-trimethylcyclopentadienyl)
(2 ′, 4 ′, 5′-trimethylcyclopentadienyl) zirconium dimethyl, dimethylsilylbis (t-
Butylcyclopentadienyl) zirconium dimethyl,
Dimethylsilylbis (trimethylsilylcyclopentadienyl) zirconium dimethyl, dimethylsilylbis (2-trimethylsilyl-4-t-butylcyclopentadienyl) zirconium dimethyl, dimethylsilylbis (4,5,6,7-tetrahydro-indenyl) Zirconium dimethyl, dimethylsilylbis (indenyl) zirconium dimethyl, dimethylsilylbis (2-methylindenyl) zirconium dimethyl, dimethylsilylbis (2,4-dimethylindenyl) zirconium dimethyl, dimethylsilylbis (2,4,7- Trimethylindenyl) zirconium dimethyl, dimethylsilylbis (2-methyl-4-phenylindenyl) zirconium dimethyl, dimethylsilylbis (2-ethyl-4-phenylindenyl) zyl Dimethyl, dimethylsilylbis (benz [e] indenyl) zirconium dimethyl, dimethylsilylbis (2-methylbenz [e] indenyl) zirconium dimethyl, dimethylsilylbis (3-methylbenz [e] indenyl) zirconium dimethyl, dimethylsilylbis ( Benz [f] indenyl) zirconium dimethyl, dimethylsilylbis (2-
Methylbenz [f] indenyl) zirconium dimethyl, dimethylsilylbis (3-methylbenz [f] indenyl) zirconium dimethyl, dimethylsilylbis (cyclopenta [cd] indenyl) zirconium dimethyl and the like and zirconium of the above metallocene compound was replaced with titanium or hafnium. Metallocene compounds and the like.

Further, ethylenebis (indenyl) zirconium dichloride, ethylenebis (4,5,6,7-
Tetrahydroindenyl) zirconium dichloride,
1,2-dimethylethylidyl-1,2-bis (indenyl) zirconium dichloride, 1,2-dimethylethylidyl-1,2-bis (2′-methylindenyl) zirconium dichloride, 1,2-diisopropyl Ethyridyl-1,2-bis (indenyl) zirconium dichloride, 1,2-diisopropylethylidyl-1,2
-Bis (2′-methylindenyl) zirconium dichloride, 1,2-dimethylethylidyl-1,2-bis (3′-methylindenyl) zirconium dichloride,
1,2-dimethylethylidyl-1,2-bis (4′-
Isopropylindenyl) zirconium dichloride,
1,2-dimethylethylidyl-1,2-bis (4 ′,
7'-diisopropylindenyl) zirconium dichloride, 1,2-dimethylethylidyl-1,2-bis (2'-methyl-4'-isopropylindenyl) zirconium dichloride, 1,2-dimethylethylidyl-
1,2-bis (4′-cyclohexylindenyl) zirconium dichloride, 1,2-dimethylethylidyl-
1,2-bis (2′-methyl-4′-cyclohexylindenyl) zirconium dichloride, 1,2-dimethylethylidyl-1,2-bis (4′-phenylindenyl) zirconium dichloride, 1,2- Dimethylethylidyl-1,2-bis (4 ', 7'-diphenylindenyl) zirconium dichloride, 1,2-dimethylethylidyl-1,2-bis (2'-methyl-4'-phenylindenyl) ) Zirconium dichloride, 1,2-dimethylethylidyl-1,2-bis (4′-naphthylindenyl) zirconium dichloride, 1,2-dimethylethylidyl-1,2-bis (2′-methyl-4) '-Naphthylindenyl) zirconium dichloride, 1,2-dimethylethylidyl-1,2-bis (5'-phenylindenyl) zirconium dichloride 1,2-dimethylethylidyl-1,2-bis (4′-methoxyindenyl) zirconium dichloride, 1,2-dimethylethylidyl-1,2-bis (benz [e] indenyl) zirconium dichloride, 1,2-dimethylethylidyl-
1,2-bis (2'-methylbenz [e] indenyl)
Zirconium dichloride, 1,2-dimethylethylidyl-1,2-bis (3′-methylbenz [e] indenyl) zirconium dichloride, 1,2-dimethylethylidyl-1,2-bis (benz [f] indenyl ) Zirconium dichloride, 1,2-dimethylethylidyl-
1,2-bis (2′-methylbenz [f] indenyl)
Zirconium dichloride, 1,2-dimethylethylidyl-1,2-bis (3'-methylbenz [f] indenyl) zirconium dichloride, 1,2-dimethylethylidyl-1,2-bis (cyclopenta [cd] indenyl ) Zirconium dichloride or ethylenebis (indenyl) zirconium dimethyl, ethylenebis (4
5,6,7-tetrahydroindenyl) zirconium dimethyl, 1,2-dimethylethylidyl-1,2-bis (2'-methyl-4'-isopropylindenyl) zirconium dimethyl, 1,2-dimethylethyl Jiyl-
1,2-bis (4 ′, 7′-diisopropylindenyl) zirconium dimethyl, 1,2-dimethylethylidyl-1,2-bis (2′-methyl-4′-phenylindenyl) zirconium dimethyl, , 2-Dimethylethylidyl-1,2-bis (2'-methyl-4'-naphthylindenyl) zirconium dimethyl, 1,2-dimethylethylidyl-1,2-bis (benz [e] indenyl) Zirconium dimethyl, 1,2-dimethylethylidyl-1,2-bis (2′-methylbenz [e] indenyl) zirconium dimethyl, 1,2-dimethylethylidyl-1,2-bis (3′-methylbenz [ e) indenyl) zirconium dimethyl and the like and metallocene compounds in which zirconium of the above metallocene compound is replaced with titanium or hafnium. That.

Examples of the organometallic compound component include an organic aluminum oxy compound and an organic aluminum compound. As the organic aluminum oxy compound, a conventionally known aluminoxane can be used, and an organic aluminum compound may be mixed with the aluminum oxy compound. The aluminum oxy compound has 1 to 1 carbon atoms.
Those obtained by reacting trialkylaluminum, dialkylaluminum halide or the like having 2 alkyl groups with water can be preferably used.

In the present invention, an organometallic compound can be used in combination with propylene polymerization. As the organometallic compound, the metal is an alkyl metal compound selected from Group 1, Group 2, Group 12, and Group 13 of the periodic table, and specifically, lithium, sodium, potassium, or beryllium, magnesium, or It is an organometallic compound composed of zinc, cadmium or aluminum, gallium and alkyl having 1 to 20 carbon atoms. Particularly preferred are alkyl aluminum compounds having 1 to 20 carbon atoms. Further, specific examples of the alkylaluminum compound include trimethylaluminum, triethylaluminum, trin-propylaluminum, triisopropylaluminum, trin-butylaluminum, triisobutylaluminum, trisec-butylaluminum, dimethylaluminum chloride, and diethylaluminum chloride. , Di-n-propylaluminum chloride, diisopropylaluminum chloride, di-n-butylaluminum chloride, diisobutylaluminum chloride, dise
c-butylaluminum chloride and the like, particularly preferably trimethylaluminum, triethylaluminum, trin-propylaluminum, triisopropylaluminum, trin-butylaluminum, triisobutylaluminum, trisec-butylaluminum and the like.

In a preferred embodiment of the present invention, aluminoxane is used as at least one component of the organometallic compound component, supported on a carrier as described below, and another organometallic compound component, particularly preferably trialkylaluminum, is used in combination during polymerization. That is. Here, instead of aluminoxane, an ionic compound that converts a metallocene compound into a cationic compound and generates a stable counter anion species can be used. As specific examples, triphenylcarbenium tetrakis (pentafluorophenyl) borate, ferrocenium tetrakis (pentafluorophenyl) borate, N, N-dimethylammonium tetrakis (pentafluorophenyl) borate, tri-n-butylammonium tetrakis (pentafluoro) Phenyl)
Carbenium borane such as borate, triethylammonium tetratetrakis (phenyl) borate, tri-n-butylammonium tetra (phenyl) borate,
Metalablan, ammonium borane, and the like.

In the present invention, the homogeneous catalyst preferably contains a carrier. As the carrier, a transition metal compound component, an organometallic compound component, or a metallocene compound is converted into a cationic compound, and a stable counter anion is used. Any one of the ionic compounds that produce the compound may be supported. However, the one in which an aluminoxane is supported on a carrier can be preferably exemplified from the viewpoint that the activity of the catalyst is good and the catalyst can be produced relatively inexpensively.

As the carrier, those using an organic polymer as a carrier in addition to inorganic oxides such as silica and alumina or a mixture or composite thereof can be used. When an organic polymer is used as a carrier as compared with a case where an inorganic oxide or a mixture thereof is used as a carrier, it is preferable to use an organic polymer as a carrier because of less generation of fish eyes or gel in a product. The polymer is obtained by grafting or graft-polymerizing an unsaturated compound containing a carbonyl group. For example, polymer compounds having no functional group such as polyethylene, polypropylene, ethylene-propylene copolymer, polybutene, ethylene-butene copolymer, ethylene-propylene-butene copolymer, polyisobutene, polypentene, poly4-methylpentene, polynorbornene, polybutadiene, and poly For high molecular compounds such as isoprene, polystyrene, poly-α-methylstyrene, polyethylene oxide, polypropylene oxide, polytetrahydrofuran, and polysiloxane, preferably polyethylene, polypropylene, ethylene-propylene copolymer, polybutene, ethylene-butene copolymer, ethylene-propylene. Butene copolymer, polyisobutene, polypentene, poly-4-methylpentene, polynorbornene, polybutadiene, In lysoprene, polystyrene, poly-α-methylstyrene, for example, methacrylic acid which is an unsaturated compound containing a group having a carbonyl group, acrylic acids such as acrylic acid, methyl methacrylate, 3-methacryloxypropyltrimethoxysilane, acrylic Acrylates such as methyl acrylate, methacrylamide, acrylamide,
Acrylamides such as crotonamide, vinyl acetate, methyl vinyl ketone, acryloyl chloride, vinyls such as acrylaldehyde, carboxylic anhydrides such as maleic anhydride and itaconic anhydride, and dicarboxylic acids such as maleic acid and itaconic acid. Organic polymer compounds obtained by grafting or graft polymerization by a radical reaction or the like can be mentioned.

In the present invention, not only homopolymerization of propylene but also ethylene and other α-olefins such as butene-1, 3-methylbutene-1, pentene-1, hexene-1, 4-methylpentene, and norbornene, Random polymerization with styrene or the like or block copolymerization may be performed.

[0021]

EXAMPLES The present invention will be described below with reference to Examples, but the present invention is not limited to these Examples.

In the present invention, the melting point (Tm), molecular weight distribution index (PDI), intrinsic viscosity ([η]), melt flow index (MFI) and fish eye or gel (FE) were measured by the following methods. Melting point (Tm): The melting point (Tm) measured by differential scanning calorimetry (DSC) was measured under the following conditions. [measuring device:
Perkin Elmer DSC-4, heating rate: 10 ° C / mi
n, temperature drop rate: -10 ° C / min, or -30 ° C / m
in]. -Molecular weight distribution index (PDI = Mw / Mn): Number average molecular weight (M
n) and weight average molecular weight (Mw) were measured under the following conditions. [Measurement device: Waters 150CVplus,
Column: Shodex GPC AD-80M / S (exclusion limit: 2 × 10 ⁷ ), mobile phase: 1,3,5-trichlorobenzene, column temperature: 135 ° C., measurement flow rate: 1.0
ml / min, sample concentration: 0.2 wt / vol%, injector capacity: 0.200 ml, detector: differential refractometer and viscometer, standard sample: polystyrene standard]. -Intrinsic viscosity ([η]): The viscosity was measured with a tetralin solution at 135 ° C.・ Melt flow index (MFI): 2.16 kg
It was measured by weight. Fish eye or gel (FE: hereinafter simply referred to as fish eye): 0.1% by weight of Irganox 168 (manufactured by Ciba-Geigy) and 0.05% by weight of Irgafos 1010 (manufactured by Ciba-Geigy) in a polypropylene powder obtained by polymerization. After adding and mixing, resin temperature 2
Pellet at 20 ° C, then 20mmφ downward TD
It was melt-extruded with an IE extruder at a resin temperature of 250 ° C. to obtain a film having a thickness of 50 μm or more. The number of fish eyes of 100 μm or more and the number of fish eyes of less than 100 μm per 600 cm ² area of the film were measured.

Example 1 Polymerization was carried out using a reactor having the shape shown in FIG.
As a homogeneous catalyst, diphenylmethylene (cyclopentadienyl-fluorenyl) zirconium dichloride synthesized by a conventional method as a transition metal compound component was used, and methylaluminoxane (manufactured by Albemarle) was used as an organometallic compound component. Maleic acid grafted (manufactured by Mitsui Toatsu Chemicals, Inc. (trade name: Ronply)) Maleic anhydride content: 6.64 wt%,
0.68 mmol / g) were mixed at 140 ° C. in 4200 ml of xylene with 28.8 g of methylaluminoxane and 20 g of GPP supported on a solid catalyst component, and cooled to 20 ° C.
A product obtained by separating, drying, and further pulverizing a solid content into fine pieces. )
Was used. (Pretreatment of homogeneous catalyst component) In an autoclave having an inner volume of 200 L (liter), 120 L of heptane, 21.5 g of triisobutylaluminum, and 1.0 g of diphenylmethylene (cyclopentadienyl-fluorenyl) zirconium dichloride as a transition metal compound component. Then, 120 g of the above solid catalyst component was charged, and then 1200 g of propylene was charged while keeping the internal temperature at 25 ° C., and reacted for 2 hours to obtain a pretreated catalyst component slurry. When a part was sampled and analyzed, this solid catalyst component contained 0.13% by weight of zirconium, and 9
g of propylene had been polymerized. (Polymerization reaction) Referring to FIG. 1, propylene was added to a 60-L annular reactor 1 (first polymerization zone) at a rate of 52 kg / hour.
37 NL / hour with hydrogen dissolved in propylene,
As the catalyst, the pretreated catalyst component slurry was continuously supplied at a rate of 1.72 g / hour as a solid catalyst component and 5.76 g / hour of triisobutylaluminum. Polymerization was carried out in a liquid state. The temperature of the annular reactor 1 is 45 ° C.
The pressure was 33 kg / cm ² -G (gauge), and the polymer yield per transition metal compound in this polymerization zone calculated from the material balance was 44 kg-PP / mmol-transition metal catalyst component. The resulting slurry has an internal volume of 1000 L
Was continuously fed to the second polymerization machine 2 (the polymerization zone in the latter stage) to further polymerize. 30 kg of propylene is supplied to the second polymerization machine 2.
/ Hour, temperature is 70 ° C., pressure is 30 kg / cm ²
-G and hydrogen were supplied while being adjusted such that the hydrogen concentration in the gas phase became 1.7 mol%. The resulting slurry has an internal volume of 50
The slurry was continuously fed by a slurry circulation pump 4A to a 0 L third polymerization machine 3 (a polymerization zone in the latter stage) to further polymerize. The propylene is supplied to the third polymerization machine 3 at a rate of 33 kg / hour, the temperature is 68 ° C., the pressure is 29 kg / cm ² -G, and the hydrogen is adjusted so that the hydrogen concentration in the gas phase becomes 1.7 mol%. It was fed and polymerized. The slurry leaving the third polymerization machine 3 was deactivated by adding alcohol, and after removing unreacted monomers, the polymerization powder was recovered. Powder was obtained at 27 kg / h. The obtained powder was dried at 80 ° C. and 60 mmHg for 10 hours to obtain a product. The yield of polymer per transition metal compound calculated from the material balance was 1070 kg-
PP / mmol-transition metal catalyst component. [Η] of the product is 1.40 dl / g and MFI is 2.9 g / 10 m
in, Tm is 134.6 ° C., PDI is 2.3, and FE is 100 μm or more in number of fish eyes.
The number of three fish eyes having a size of less than 100 μm was 30.

Comparative Example 1 Referring to FIG. 2, a catalyst was directly introduced from a catalyst supply nozzle 5A into a second polymerization machine 2 without using the annular reactor 1 of FIG. The polymerization was carried out as in Example 1 with circulation. At a polymerization temperature of 70 ° C., the nozzle was closed immediately after the start of the catalyst insertion. Therefore, the polymerization was performed at a polymerization temperature of 60 ° C. Since the catalyst nozzle was blocked at 0.5 hours after the start of polymerization, the catalyst was inserted from the catalyst supply nozzle 5B provided in the slurry circulation line (at a temperature of 58 ° C.). At this time, the temperature of the third polymerization machine 3 is 5
7 ° C. The polymer yield per transition metal compound calculated from the material balance was only 456 kg-PP / mmol.

[0025]

By carrying out the method of the present invention, it is possible to stably produce polypropylene at a high yield per catalyst, which is extremely valuable industrially.

[Brief description of the drawings]

FIG. 1 is a flowchart showing an example of a polymerization apparatus suitable for carrying out the present invention.

FIG. 2 is a flowchart showing an example of a polymerization apparatus used to carry out a conventional method.

[Explanation of symbols]

 Reference Signs List 1 annular reactor (first polymerization zone) 2 second polymerization machine 3 third polymerization machine 4, 4A slurry circulation pump 5A, 5B catalyst supply nozzle

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Harima, 1-6-6 Takasago, Takaishi City, Osaka Prefecture Inside Mitsui Toatsu Chemical Co., Ltd. (72) Inventor Koji Yoshikawa 1-6, Takasago, Takaishi City, Osaka Mitsui Toatsu Chemical Inside the corporation

Claims (6)

[Claims] 1. A method for continuously polymerizing propylene using a homogeneous catalyst in a polymerization system comprising at least two polymerization zones and using propylene itself as a liquid medium,
In the first polymerization zone, polymerization of 1/5 or less of the total polymerization amount is carried out at a temperature lower than the highest polymerization temperature of the subsequent polymerization zone by 10 ° C. or more and in a liquid-full state in which no gas phase is present. A process for the polymerization of propylene, characterized in that the remaining polymerization is carried out at 60 ° C. or higher in at least one subsequent polymerization zone under the conditions present. 2. The method according to claim 1, wherein the homogeneous catalyst is a catalyst comprising a metallocene compound and an organometallic compound. 3. The method according to claim 1, wherein the homogeneous catalyst contains a component in which aluminoxane is supported on a polymer. 4. The method according to claim 1, wherein the first polymerization zone is a cyclic reactor in which propylene is refluxed at a linear velocity of 2.0 m / sec or more. 5. The process according to claim 1, wherein the propylene charged to the first polymerization zone contains hydrogen. 6. The process according to claim 1, wherein the homogeneous catalyst charged in the first polymerization zone is obtained by polymerizing 0.1 to 100 g / g of propylene per solid catalyst component.