JPH1060044A - Production of ethylenic polymer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for simply producing an ethylenic polymer wide in mol.wt. distribution and large in melt tension and die swell in the presence of a catalyst simple in its preparation and handling. SOLUTION: This method for producing an ethylenic polymer comprises using a catalyst obtained by suspending a chromium halide compound and a solid inorganic oxide in an ether solvent, treating the suspension with a cycloalkadienyl salt, and subsequently treating the obtained solid component with an aluminoxane.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing an ethylene polymer. More specifically, the present invention relates to a method for producing an ethylene polymer having a wide molecular weight distribution and a large melt tension and a large die swell, which is suitable for blown film molding and blow molding using a chromium catalyst.

[0002]

2. Description of the Related Art Conventionally, a method for producing an ethylene polymer using a catalyst in which an organic chromium compound having a cycloalkadienyl group is supported on an inorganic oxide solid has already been disclosed in JP-B-45-40902 and JP-B-55. -8086, JP-A-3-93804, JP-A-3-93805, JP-A-3-93805
-93809 and JP-A-6-145233. That is, in Japanese Patent Publication No. 45-40902, bis (cyclopentadienyl) chromium is supported, and in Japanese Patent Publication No. 55-8086, bis (indenyl) chromium or bis (fluorenyl) chromium is supported on an inorganic oxide solid. Is used to produce ethylene polymers. However, ethylene polymers obtained with these catalysts have a narrow molecular weight distribution, low melt tension and low die swell, and are not suitable for blown film molding or blow molding. Also, Japanese Patent Application Laid-Open No. 3-93804
JP-A-3-93805, JP-A-3-93809
In the inventions such as JP-A-6-145233,
A catalyst is used in which a synthesized and isolated organic chromium compound having a substituted cyclopentadienyl ligand is supported on an inorganic oxide solid. Ethylene polymers produced using these catalysts have a wide molecular weight distribution, but the organic chromium compounds used are very sensitive to oxygen and moisture in the air and are prone to deterioration, which is not only inconvenient to handle, but also These organic chromium compounds have the disadvantage that the synthesis process is also very complicated.

[0003] Recently, in Japanese Patent Application Publication No. 7-503739, the use of a catalyst consisting of an organic chromium compound having a cycloalkadienyl group, an inorganic oxide solid and an alumoxane to change the molar ratio between alumoxane and chromium during polymerization. A method for producing an ethylene-based polymer in which the molecular weight distribution is controlled by the method has been disclosed. According to this method, an ethylene polymer having a wide molecular weight distribution can be obtained, but it is not practical because the production process is extremely complicated and the operation is difficult. Therefore, a chromium-based catalyst having a cycloalkadienyl group supported on an inorganic oxide solid, and having a wide molecular weight distribution suitable for inflation film molding and blow molding using a catalyst obtained by a simple process, It has been desired to develop a method for producing an ethylene polymer having a large melt tension and a large die swell.

[0004]

DISCLOSURE OF THE INVENTION The present invention provides a catalyst having a wide molecular weight distribution, a wide molecular weight distribution, and a high melt tension, which is simple in the preparation and handling of the above-mentioned catalyst and in the process of synthesizing an ethylene-based polymer. And a method for efficiently producing an ethylene polymer having a large die swell.

[0005]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies in view of the above-mentioned problems. As a result, (1) after suspending a chromium halide compound and an inorganic oxide solid in an ether solvent, cycloalkadienyl was added. A method for producing an ethylene-based polymer using a catalyst obtained by treating a solid component treated with a salt with alumoxane, and (2) the ethylene-based polymer according to (1), wherein the chromium halide compound is chromium chloride or a chromium chloride complex. The above object has been achieved by developing a manufacturing method of coalescence.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be specifically described below.
As the chromium halide compound used in the present invention, chromium dichloride, chromium trichloride, chromium difluoride, chromium trifluoride, chromium dibromide, chromium tribromide, chromium diiodide,
Halides such as chromium triiodide,
Among them, chromium dichloride or chromium trichloride is preferred.
Also, a chromium trichloride tetrahydrofuran complex (CrC
l ₃ · 3THF) or double tetrahydrofuran complex of chromium chloride (CrCl ₂ · 2THF) is also preferably used.

The cycloalkadienyl salts include cyclopentadienyl lithium, cyclopentadienyl sodium, cyclopentadienyl potassium, methylcyclopentadienyl lithium, methylcyclopentadienyl sodium, methylcyclopentadienyl potassium, Pentamethylcyclopentadienyl lithium, pentamethylcyclopentadienyl sodium, pentamethylcyclopentadienyl potassium, indenyl lithium, indenyl sodium, indenyl potassium, fluorenyl lithium, fluorenyl sodium, fluorenyl potassium , 9-methylfluorenyllithium, 9-methylfluorenylsodium, 9-methylfluorenylpotassium and the like. These cycloalkadienyl salts can be obtained by reacting the corresponding cycloalkadiene with lithium, sodium or potassium in an ether solvent in a known manner.

[0008] As the inorganic oxide solid, the periodic table No. 2
An oxide of a metal of group 4, 4, 13 or 14;
Specifically, magnesia, titania, zirconia, silica, alumina, silica-alumina, silica-titania,
Examples thereof include silica-zirconia, aluminum phosphate, and mixtures thereof. These inorganic oxide solids have a specific surface area of 50 to 1000 m ² / g, preferably 200 to 200 m ² / g.
８００800 m ² / g, pore volume of 0.5 to 3.0 cm ³ /
g, preferably 1.0 to 2.5 cm ³ / g, and an average particle size of 10 to 200 μm, preferably 50 to 150 μm. It is desirable that the inorganic oxide solid be calcined before use to remove adsorbed moisture before use. The calcination of the inorganic oxide solid is usually carried out at a temperature of 1 under a stream of nitrogen gas dried by flowing through a molecular sieve layer.
The process is arbitrarily selected from the range of 00 to 900 ° C and the range of 30 minutes to 24 hours. It is preferable to dry under a fluidized state of a solid with a sufficient amount of nitrogen gas.

Alumoxane is a compound well known in the art, but its preparation and structure are Polyhed.
ron, 9, 429-453 (1990), Ziegl
erCatalysts, G. et al. Fink et al.
(Eds.) 57-82, Springer-Verl.
ag (1995). The alumoxane used in the present invention has the following general formula (1)
Or the compound represented by (2) is mentioned.

[0010]

Embedded image

Embedded image (R ¹ is a hydrocarbon group such as a methyl group, an ethyl group, a propyl group, an n-butyl group, and an isobutyl group, and is preferably a methyl group or an isobutyl group.
, Preferably 4 or more, particularly preferably 8 or more. )

The preparation of such compounds is well known, and examples thereof include salts having water of crystallization (such as copper sulfate hydrate and aluminum sulfate hydrate) such as pentane, hexane, heptane, cyclohexane, decane, benzene and toluene. Examples thereof include a method of adding a trialkylaluminum to a suspension of an inert hydrocarbon solvent to obtain the same, and a method of allowing solid, liquid, or gaseous water to act on a trialkylaluminum in a hydrocarbon solvent. .

Further, an alumoxane represented by the general formula (3) or (4) may be used.

Embedded image

Embedded image (R ² is a hydrocarbon group such as a methyl group, an ethyl group, a propyl group, an n-butyl group, an isobutyl group, and is preferably a methyl group or an isobutyl group. Further, R ³ is a methyl group, an ethyl group. , propyl group, n- butyl group, a hydrocarbon group such as an isobutyl group or a chlorine, a halogen or hydrogen bromine, selected from hydroxyl, show different groups and R ^2. also, R ³ is be the same or different Q is usually 1 to 100, preferably 3 or more, and q
+ R is 2 to 100, preferably 6 or more. )

In the general formula (3) or (4), [OA
The l (R ² )] _q unit and the [O-Al (R ³ )] _r unit may be combined in blocks or may be combined regularly or irregularly at random. . The method for producing such an alumoxane compound is the same as that for the alumoxane of the general formula described above, and instead of one kind of trialkylaluminum, two or more kinds of trialkylaluminum are used, or one or more kinds of trialkylaluminum are used. More than one kind of dialkylaluminum monohalide or dialkylaluminum monohydride may be used.

The catalyst used in the method of the present invention is produced by chemically reacting a chromium halide compound, a cycloalkadienyl salt, an inorganic oxide solid and alumoxane. That is, a chromium halide compound and an inorganic oxide solid are suspended in an ether solvent, and then the suspension is treated with a cycloalkadienyl salt, and the resulting solid component is treated with alumoxane. Examples of the ether solvent used to suspend the chromium halide compound in the inorganic oxide solid include diethyl ether, diisopropyl ether, dioxane, 1,2-dimethoxyethane, and aliphatic or alicyclic ethers such as tetrahydrofuran. Among them, tetrahydrofuran is preferred. The amount of the chromium halide compound added to the inorganic oxide solid is:
Chromium atom is 0.01 to 10 with respect to the inorganic oxide solid.
%, preferably 0.1 to 5% by weight. A cycloalkadienyl salt is added to the suspension to cause a reaction. The molar ratio of the chromium atom to the cycloalkadienyl salt in the chromium salt is 1: 1 to 1:10, preferably 1: 1 to 1 Perform at 1: 5. The reaction temperature is -78 ° C to the boiling point of the solvent, preferably -20 ° C to 50 ° C, and the reaction time is 10 minutes to 24 hours, preferably 30 minutes to 5 hours. By this reaction, chromium atoms are supported on the inorganic oxide solid. After the reaction, a solid component having good fluidity can be obtained by a method of removing the solvent under vacuum or a method of separating by filtration.

The treatment of the solid component with alumoxane is carried out in an inert hydrocarbon such as pentane, hexane, heptane, cyclohexane, benzene, toluene and the like. The aluminum atom in the alumoxane used for the treatment has an aluminum / chromium molar ratio of 1 to 1000, preferably 5 to 1 with respect to the chromium atom in the solid component.
It is preferable to carry out the treatment in such an amount as to give 00. The reaction temperature is -78 ° C to the boiling point of the solvent, preferably -20 ° C to 50 ° C.
C., and the reaction time is 10 minutes to 24 hours, preferably 30 minutes.
Minutes to 5 hours. After the treatment, a catalyst having good fluidity can be obtained by a method of removing the solvent under vacuum or a method of separating by filtration.

In carrying out the method of the present invention using the above catalyst, the polymerization method of ethylene includes slurry polymerization,
A liquid phase polymerization method such as solution polymerization or a gas phase polymerization method is possible. The liquid phase polymerization method is usually carried out in a hydrocarbon solvent, and as the hydrocarbon solvent, an inert hydrocarbon such as butane, isobutane, hexane, cyclohexane, benzene, toluene, xylene or a mixture thereof is used. The polymerization temperature is generally from 0 to 300C, and practically from 20 to 200C. Further, hydrogen or the like can coexist in the polymerization system for controlling the molecular weight. further,
Propylene, 1-butene, 1-hexene,
Α-olefins such as 4-methyl-1-pentene and 1-octene may be used alone or in a combination of two or more kinds for polymerization.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples. In Examples and Comparative Examples, the melt flow rate (hereinafter, referred to as “MFR”) was measured at a temperature of 190 ° C. and a load of 2.16 kgf in accordance with JIS K-7210, Test Condition 4 of Table 1. High Load Melt Flow Rate (hereinafter "HLM"
FR ") was measured at a temperature of 190 ° C and a load of 21.6 kgf in accordance with JIS K-7210 Table 1, Test Condition 7. The larger the value obtained by dividing the HLMFR by the MFR, that is, the larger the value of HLMFR / MFR, the wider the molecular weight distribution. The melt tension was measured using a melt tension tester manufactured by Toyo Seiki Co., Ltd. at a resin temperature of 190 ° C., an orifice diameter of 2.095 mm, an orifice length of 8 mm, an extrusion speed of 15 mm / min, and a winding speed of 6.5 mm / m.
It was measured under the conditions of "in". Die swell ratio (hereinafter "S
R ") uses the same device as HLFR, and uses HLMF
The degree of expansion (%) of the outer diameter of the extruded material with respect to the orifice system at the time of R measurement was shown. The samples used for these measurements were previously measured using a plastograph manufactured by Toyo Seiki Co., Ltd.
0.2 wt% of B225 manufactured by Ciba-Gaiky as an additive
After the addition, kneading was performed at 190 ° C. for 7 minutes under a nitrogen atmosphere.

[0018]

【Example】

Example 1 (1) Preparation of Catalyst 35 ml of tetrahydrofuran was added to 3.0 g of DAVISON 952 grade silica calcined at 600 ° C. for 4 hours to form a slurry. Aldrich Corp. CrCl ₃ · 3THF complex 45.0mg in this slurry (0.12mm
ol; 0.2 wt% as a chromium atom carrying amount). After heating to 40 ° C., 2.0 mol from Aldrich
/0.1 0.18 ml (0.36 mmol) of a solution of sodium cyclopentadienyl in tetrahydrofuran was added. After stirring at 40 ° C. for 1 hour, the solvent was completely removed under vacuum to obtain a solid component. Toluene 35 is added to the obtained solid component.
ml was added to obtain a slurry. To this slurry was added 0.6 ml (1.2 mmol) of a 2.0 mol / 1 toluene solution of methylalumoxane manufactured by Toku-Akzo Co., Ltd.
For 2 hours. The solvent was removed under vacuum to obtain the catalyst. (2) Ethylene polymerization 0.6 L of isobutane and 200 mg of the catalyst obtained above were charged into a 1.5 L autoclave sufficiently purged with nitrogen, and the internal temperature was raised to 100 ° C. Then, 0.5 kg / cm ^{2 of} hydrogen was added at a gauge pressure, ethylene was further injected, and polymerization was carried out for 1 hour while maintaining the ethylene partial pressure at 14 kg / cm ² . Then, the polymerization was terminated by discharging the content gas out of the system. As a result, 62
g of polyethylene were obtained. The polymerization activity was 310 g polymer / g catalyst / hour. MFR of this polymer =
0.11, HLMFR = 6.4, HLMFR / MFR =
58.2, and the molecular weight distribution was broad. Further, the melt tension was 30.2 g and the SR was 87%.

Example 2 In the preparation of the catalyst of Example 1 (1), the amount of methylalumoxane added was 1.2 ml.
(2.4 mmol), except that the catalyst was prepared and polymerized in the same manner as in Example 1. The results are shown in Table 1. (Example 3) In the preparation of the catalyst of Example 1 (1), Aldrich was used instead of sodium cyclopentadienyl.
0.5 mol / 1 tetrahydrofuran solution of sodium pentamethylcyclopentadienyl manufactured by
A catalyst was prepared and polymerized in the same manner as in Example 1 except that ml (0.36 mmol) was added. The results are shown in Table 1. (Example 4) In the preparation of the catalyst of Example 1 (1), in place of cyclopentadienyl sodium, synthesized from indene and butyllithium according to “Experimental Chemistry Course (4th edition)”, Vol. 18, p. 27 (Maruzen). 1.0 mol / 1 solution of indenyl lithium in tetrahydrofuran was added to 0.36
A catalyst was prepared and polymerized in the same manner as in Example 1 except that ml (0.36 mmol) was added. The results are shown in Table 1. (Example 5) In the preparation of the catalyst of Example 1 (1), instead of sodium cyclopentadienyl, synthesized from fluorene and butyllithium according to “Experimental Chemistry Lecture (4th edition)”, Vol. 18, p. 27 (Maruzen). 1.0 mol / 1 solution of fluorenyllithium in tetrahydrofuran was added to 0.1 ml.
A catalyst was prepared and polymerized in the same manner as in Example 1 except that 36 ml (0.36 mmol) was added. The results are shown in Table 1.

Comparative Example 1 (1) Preparation of Catalyst 50 ml of toluene was added to 3.0 g of DABISON 952 grade silica calcined at 600 ° C. for 4 hours to form a slurry. Bis (cyclopentadienyl) synthesized from chromium trichloride and cyclopentadienyl sodium according to "New Experimental Chemistry" Vol. 12, p. 110 (Maruzen)
21 mg (0.12 mmol; 0.2 wt% as a chromium atom carrying amount) of chromium was added, and the mixture was stirred at 40 ° C. for 1 hour. 0.6 ml of a 2.0 mol / l toluene solution of methylalumoxane manufactured by Tosoh Akzo Co., Ltd.
(1.2 mmol) and stirred at 40 ° C. for 2 hours. The solvent was removed under vacuum to obtain the catalyst. (2) Ethylene polymerization Using the bis (cyclopentadienyl) chromium-supported catalyst obtained in (1), polymerization was carried out in the same manner as in Example 1. The results are shown in Table 1. The molecular weight distribution was narrower than in Examples 1 to 5, and the melt tension and SR were both low.

Comparative Example 2 (1) Preparation of Catalyst 50 ml of toluene was added to 3.0 g of DAVISON 952 grade silica calcined at 600 ° C. for 4 hours to form a slurry. To this, Karol et al. (Journalof P
Polymer Science: Polymer Ch
emitoryEdition, 16, 771 (197
8)) bis (indenyl) chromium synthesized from chromium trichloride and indenyl sodium by 32.5 m
g (0.12 mmol; 0.2 as chromium atom carrying amount)
wt%) and stirred at 40 ° C. for 1 hour. To this slurry was added 2.0 mL of methylalumoxane manufactured by Tosoh Akzo.
mol / l toluene solution 0.6 ml (1.2 mmol
l) was added and stirred at 40 ° C. for 2 hours. The solvent was removed under vacuum to obtain the catalyst. (2) Ethylene polymerization Using the bis (indenyl) chromium-supported catalyst obtained in (1), polymerization was carried out in the same manner as in Example 1. The results are shown in Table 1. The molecular weight distribution was narrower than in Examples 1 to 5, and the melt tension and SR were both low.

Comparative Example 3 (1) Preparation of Catalyst 50 ml of toluene was added to 3.0 g of DAVISON 952 grade silica calcined at 600 ° C. for 4 hours to form a slurry. To this, Karol et al. (Journalof P
Polymer Science: Polymer Ch
Emissions Edition, 16, 771 (19
78)). A toluene solution of bis (fluorenyl) chromium synthesized from chromium trichloride and sodium fluorenyl by the method of 78)) was mixed with 44.1% of bis (fluorenyl) chromium.
mg (0.12 mmol: 0.1 as chromium atom carrying amount).
2 wt%), and added at 40 ° C.
Stirred for hours. To this slurry was added a 2.0 mol / l toluene solution of methylalumoxane manufactured by Tozo Akzo Co., Ltd.
6 ml (1.2 mmol) was added, and the mixture was stirred at 40 ° C. for 2 hours. The solvent was removed under vacuum to obtain the catalyst. (2) Ethylene polymerization Using the bis (fluorenyl) chromium-supported catalyst obtained in (1), polymerization was carried out in the same manner as in Example 1. The results are shown in Table 1. Although the molecular weight distribution was wide, the melt tension and SR were both low.

[0023]

[Table 1]

[0024]

Industrial Applicability According to the present invention, an unstable cycloalkadienyl chromium complex is synthesized from a chromium halide and a cycloalkadienyl salt in a catalyst preparation system, and the inorganic oxidization is simultaneously carried out. Efficient production of an ethylene polymer with a broader molecular weight distribution, higher melt tension, and a larger die swell than when preparing a catalyst by synthesizing and isolating a complex. Succeeded. Therefore, the ethylene polymer obtained by the method of the present invention is a high quality ethylene polymer suitable for blown film molding and blow molding.

[Brief description of the drawings]

FIG. 1 is a flowchart of catalyst preparation in the production method of the present invention.

Claims (2)

[Claims] 1. A catalyst obtained by suspending a chromium halide compound and an inorganic oxide solid in an ether solvent and then treating the solid component treated with a cycloalkadienyl salt with alumoxane. A method for producing a polymer. 2. The method for producing an ethylene polymer according to claim 1, wherein the chromium halide compound is chromium chloride or a chromium chloride complex.