JPH1192522A - Production of ethylene polymer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce an ethylene polymer having a wider molecular weight distribution and improved in impact resistance and environmental stress cracking resistance by (co)polymerizing ethylene in the presence of a catalyst made from an organomagnesium compound and a solid inorganic oxide carrying a chromium (III) amide compound. SOLUTION: A chromium (III) amide compound of the formula (wherein R<1> to R<18> are each H or a 1-18C hydrocarbon group; and M<1> to M<6> are each C and/or Si) is mixed with a solid inorganic oxide baked at 200-450 deg.C for 30 min to 24 hr and having a specific surface of 50-1,000 m<2> /g, a pore volume of 0.5-3.0 m<2> /g and a mean particle diameter of 10-200 μm, and an organomagnesium compound so as to provide a molar ratio of Mg to Cr of (1 to 1,000):1, and the mixture is reacted in a solvent in a temperature range from -78 deg.C to the boiling point of the solvent for 10 min to 24 hr, thus giving a catalyst. Ethylene and, if necessary, an α-olefin are (co)polymerized in the presence of this catalyst to give an ethylene polymer having a number-average molecular weight (Mn) of 2,000 to 20,000, a weight-average molecular weight (Mw) of 200,000 to 600,000, and an Mw/Mn of 30 to 80.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing an ethylene polymer using a novel chromium catalyst. More specifically, the present invention relates to a method for producing an ethylene polymer for film molding or blow molding which has a wide molecular weight distribution, is excellent in impact resistance and environmental stress cracking resistance, and does not cause melt fracture.

[0002]

2. Description of the Related Art An ethylene polymer and a copolymer of ethylene and α-olefin containing ethylene as a main component (both are collectively referred to as an ethylene polymer in this specification).
Is generally and widely used as a resin material for various molded articles. Ethylene polymers differ in required properties depending on the molding method and application. For example, a polymer having a relatively low molecular weight and a narrow molecular weight distribution is suitable for a product molded by an injection molding method, whereas a product having a relatively high molecular weight is suitable for a product molded by a film molding or blow molding. Polymers having a wide molecular weight distribution are suitable.

[0003] The molecular weight distribution is related to the surface skin of a film or blown product, and it is considered that the wider the molecular weight distribution, the less the surface roughness of the molded product. That is, even in the case of a polymer having a high molecular weight, it is possible to obtain a high quality product having good fluidity without causing melt fracture on the surface skin of the molded product. In addition, when compared with the same molecular weight, the wider the molecular weight distribution, the higher the density of the ethylene-based polymer, and the higher the mechanical strength of the product. Furthermore, when compared at the same density, the wider the molecular weight distribution, the better the environmental stress cracking resistance (ESCR). On the other hand, when compared at the same molecular weight, the higher the molecular weight distribution, the higher the density and the higher the crystallinity, resulting in lower impact resistance. Therefore, impact resistance and environmental stress crack resistance (ESC)
R), which does not cause melt fracture,
There has been a demand for an ethylene polymer for film or blow molding having a wide molecular weight distribution.

Heretofore, ethylene polymers having a wide molecular weight distribution have chromium trioxide or any chromium compound which can be oxidized to chromium trioxide under the employed activation conditions supported on an inorganic oxide solid such as silica. It is known that they can be obtained by using a so-called Phillips catalyst. However, the ethylene polymer obtained by the Phillips catalyst has a molecular weight distribution (Mw / Mw) expressed by a ratio of a number average molecular weight (Mn) to a weight average molecular weight (Mw).
n) is about 8 to 30, and an ethylene polymer having a wider molecular weight distribution may be required depending on the use. There is also a problem that the ESCR is very low.

In addition, Japanese Patent Publication No. Sho 44-2996, Japanese Patent Publication No. 44-38
As described in JP-A-27-27 and JP-B-47-1766, an ethylene polymer having a wide molecular weight distribution can be obtained by using a catalyst in which chromate esters are supported on an inorganic oxide solid such as silica. The ethylene-based polymer obtained with this catalyst has a Mw / Mn value of about 20 to 60 and has a considerably wide molecular weight distribution. The ESCR has a higher impact resistance than that of the Philips catalyst, but has a low impact resistance, and is difficult to be formed into a film or blown. It has the disadvantage of causing melt fracture during molding,
There is a problem in practice.

Also, US Pat. No. 5,104,841 and US Pat.
As described in JP-A-37,997, an ethylene polymer having a wide molecular weight distribution has been obtained by using a catalyst in which a bis (trimethylsilyl) amide complex comprising a divalent chromium atom is supported on an inorganic oxide solid. The value of Mw / Mn is 50
Although the molecular weight distribution is quite wide at about 80, this catalyst has a very low polymerization activity and has a practical problem in terms of productivity. Further, the bis (trimethylsilyl) amide complex comprising a divalent chromium atom is very sensitive to air, water, and the like, so that it is very difficult to handle and is practically problematic. Further, there is a problem that impact resistance is low.

[0007] Further, as described in JP-T-7-503739, in a catalyst system using chromium acetylacetonate supported on silica and a catalyst using alumoxane,
An ethylene polymer having a wide molecular weight distribution has been obtained by changing the molar ratio of alumoxane / chromium during the polymerization. However, in this method, process control is very complicated, and there is a problem in practical use.

[0008]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the above-mentioned problems, to provide a wide molecular weight distribution, excellent impact resistance and environmental stress cracking resistance, and to avoid the occurrence of melt fracture. An object of the present invention is to provide a method for efficiently producing a polymer.

[0009]

Means for Solving the Problems The inventors of the present invention have made intensive studies in view of the above problems, and as a result, have been made of an amide compound of trivalent chromium atom, an inorganic oxide solid fired in a specific temperature range, and an organic magnesium compound. The problem has been solved by using a catalyst.

That is, the present invention provides: 1) an amide compound of a trivalent chromium atom at 100 to 500 ° C.
2. A method for producing an ethylene-based polymer, comprising using a catalyst comprising an inorganic oxide solid and an organomagnesium compound calcined in 2), 2) using the inorganic oxide solid calcined at 200 to 450 ° C. 3) The method for producing an ethylene polymer according to 1) above, wherein a catalyst obtained by supporting an amide compound of a trivalent chromium atom on an inorganic oxide solid and then reacting the amide compound with an organomagnesium compound is used. 4) The method for producing an ethylene polymer according to the above 1, wherein the ethylene polymer is polyethylene, and 5) the ethylene according to the above 1, wherein the ethylene polymer is a copolymer of ethylene and an α-olefin. Provided is a method for producing a polymer.

Hereinafter, the present invention will be described specifically. The first catalyst component used in the method of the present invention is a trivalent chromium amide compound represented by the general formula (1).

Embedded image

Wherein R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R
^{7, R 8, R 9,} R 10, R 11, R 12, R 13, R 14, R 15,
R ¹⁶ , R ¹⁷ and R ¹⁸ each represent hydrogen or C 1-18
And may be the same or different. M ¹ , M ² , M ³ , M ⁴ , M ⁵ and M ⁶ are carbon and / or
Or a silicon atom.

Specific examples of the amide compound represented by the general formula (1) include tris (dimethylamido) chromium (II
I), tris (diethylamido) chromium (III), tris (diisopropylamido) chromium (III), tris (methylphenylamido) chromium (III), tris (diphenylamido) chromium (III), tris (bistrimethylsilylamido) chromium (III), tris (bistriethylsilylamide) chromium (III), tris (bistriphenylsilylamide) chromium (III), tris (phenyltrimethylsilylamide) chromium (III), tris (t
ert-butyltrimethylsilylamide) chromium (III),
Tris (bis (dimethylphenylsilyl) amide) chromium (III), tris (bis (diphenylmethylsilyl))
Amide) chromium (III), tris (bis (dimethylvinylsilyl) amido) chromium (III) and the like.
Among these, tris (bistrimethylsilylamide)
Chromium (III) is particularly preferred.

The second catalyst component (inorganic oxide solid) used in the present invention is an oxide of a metal belonging to Group 2, 4, 13, or 14 of the periodic table. Specific examples include magnesia, titania, zirconia, silica, alumina, silica-alumina, silica-titania, silica-zirconia, aluminum phosphate, and mixtures thereof. Among these, silica-alumina and silica are preferred. The properties of these inorganic oxide solid, a specific surface area of 50~1000m ² / g, preferably 200~800m ² /
g, pore volume of 0.5 to 3.0 m ² / g, preferably 0.7 to 2.5
m ² / g, average particle size of 10 to 200 μm, preferably 3
Those having a range of 0 to 150 μm are preferably used.

The sintering of the inorganic oxide solid is usually carried out in a stream of dry nitrogen gas under a molecular sieve flow for 100 to 100 minutes.
In a temperature range of 500 ° C, preferably 200-450 ° C,
Performed for 30 minutes to 24 hours. It is preferable to supply a sufficient amount of nitrogen gas to dry the inorganic oxide solid in a fluid state. If the calcination temperature of the inorganic oxide solid exceeds 500 ° C., the polymerization activity of ethylene into high-molecular-weight polyethylene decreases, and the amount of ethylene oligomers (such as trimer 1-hexene) increases, which is not preferable.

Examples of the organomagnesium compound as the third catalyst component used in the present invention include dialkylmagnesium, alkylmagnesium alkoxide, alkylmagnesium halide and the like, with dialkylmagnesium being preferred. Specific examples include dimethylmagnesium,
Diethyl magnesium, dipropyl magnesium, dibutyl magnesium, dihexyl magnesium, dioctyl magnesium, methyl ethyl magnesium, methyl propyl magnesium, methyl butyl magnesium, methyl hexyl magnesium, methyl octyl magnesium, ethyl propyl magnesium, butyl ethyl magnesium, ethyl hexyl magnesium, ethyl octyl magnesium , Propyl butyl magnesium, propyl hexyl magnesium, propyl octyl magnesium, butyl hexyl magnesium, butyl octyl magnesium, hexyl octyl magnesium, ditert
-Butylmethylmagnesium, ditrimethylsilylmethylmagnesium, etc., of which dibutylmagnesium and butylethylmagnesium are preferred.

[Preparation of catalyst] A catalyst is prepared by chemically reacting a chromamide compound, an inorganic oxide solid and an organomagnesium compound. That is, (A) a method in which a previously synthesized chromamide compound is supported on an inorganic oxide solid and then reacted with an organomagnesium compound to form a catalyst, and (B) the chromamide compound is supported after synthesis in the presence of the inorganic oxide solid. Or a method of reacting with an organomagnesium compound to form a catalyst.

In the method for synthesizing the chromamide compound represented by the general formula (1) by the method (A), a chromium trihalide such as chromium trichloride or a tetrahydrofuran complex of chromium trichloride (CrCl ₃ .3THF) is used. ,
In an ethereal solvent such as tetrahydrofuran, an alkali metal amide such as lithium bis (trimethylsilyl) amide and an alkali metal / chromium molar ratio = 3
In general, the reaction is performed so that At that time, for example, in the case of a reaction between chromium trichloride and lithium bis (trimethylsilyl) amide, lithium chloride is precipitated as an alkali metal halide, and this precipitated salt is removed by filtration. Further, the desired chromamide compound is isolated by an operation such as recrystallization. Or without isolation,
After the removal of the alkali metal halide, the ether solvent is removed under reduced pressure, and the product is dissolved in an inert hydrocarbon solvent such as pentane, hexane, heptane, decane, cyclohexane, benzene, toluene, and xylene to produce a chromamide compound. Good.

In loading the chromamide compound on the inorganic oxide solid, pentane, hexane, heptane,
It is carried out in an inert hydrocarbon such as decane, cyclohexane, benzene, toluene, xylene and the like.

The amount of chromium atoms carried on the inorganic oxide solid is 0.01 to 10% by weight, preferably 0.03 to 5% by weight, and the reaction temperature is -78 ° C to the boiling point of the solvent, preferably -20 ° C to
60 ° C., and the reaction time is 10 minutes to 24 hours, preferably 30 minutes to 5 hours. After the supporting reaction, a solid component having good fluidity can be obtained by a method of removing the solvent under reduced pressure or a method of separating by filtration. Alternatively, the reaction with the next organomagnesium compound may be performed without removing the solvent.

The reaction of the solid component with the organomagnesium compound is carried out in an inert hydrocarbon such as pentane, hexane, heptane, decane, cyclohexane, benzene, toluene, xylene and the like. The reaction is preferably performed in such an amount that the molar ratio of magnesium atoms in the organomagnesium compound used in the reaction to the molar ratio of magnesium / chromium is 1 to 1000, preferably 5 to 300, with respect to the chromium atoms in the solid component. Reaction temperature is -78 ° C
To the boiling point of the solvent, preferably -20 ° C to 60 ° C, and the reaction time is 10 minutes to 24 hours, preferably 30 minutes to 5 hours. After the reaction, a free flowing and smooth catalyst can be obtained by a method of removing the solvent under reduced pressure or a method of separating by filtration.

In the method (B), a chromium salt and an inorganic oxide solid are suspended in an ether solvent and then treated with a corresponding metal amide to obtain a solid component carrying a chromamide compound, which is further treated with an organomagnesium compound. A method of reacting to form a catalyst is preferred.

Examples of the chromium salt include chromium trihalide such as chromium trichloride, chromium trifluoride, chromium tribromide, chromium triiodide and the like. Among them, chromium trichloride is preferred. Further, a tetrahydrofuran complex of chromium trichloride (CrCl ₃ .3THF) is also preferably used.

The metal amide is a corresponding chromium amide compound represented by the general formula (1) obtained by reacting a secondary amine or a secondary silylamine with a metal belonging to Group 1 or 2 of the periodic table. Metal amides, with lithium bis (trimethylsilyl) amide being preferred. Examples of the ether solvent used to suspend the chromium salt and the inorganic oxide solid include diethyl ether, diisopropyl ether, dioxane, 1,2-dimethoxyethane, and aliphatic or alicyclic ethers such as tetrahydrofuran. Ether and tetrahydrofuran are preferred.

The amount of the chromium salt added to the inorganic oxide solid is such that the chromium atom is 0.01 to 10 w
t%, preferably 0.03 to 5 wt%. A metal amide is added to this suspension to cause a reaction, and the chromium salt and the metal amide are reacted in such an amount that the metal amide / chromium molar ratio becomes 3.

The reaction temperature is from -78 ° C to the boiling point of the solvent, preferably from -20 ° C to 60 ° C, and the reaction time is from 10 minutes to 24 hours, preferably from 30 minutes to 5 hours. By this reaction, a chromamide compound is synthesized and immediately supported on the inorganic oxide solid in the same reaction system. After the reaction, a solid component having good fluidity can be obtained by a method of removing the solvent under reduced pressure or a method of separating by filtration.

The reaction of the solid component with the organomagnesium compound is carried out in an inert hydrocarbon such as pentane, hexane, heptane, decane, cyclohexane, benzene, toluene, xylene and the like. The reaction is preferably carried out in such an amount that the magnesium / chromium atom ratio in the organomagnesium compound used for the reaction becomes 1 to 1000, preferably 5 to 300, with respect to chromium atoms in the solid component.

The reaction temperature is -78 ° C to the boiling point of the solvent, preferably -20 ° C to 60 ° C, and the reaction time is 10 minutes to 24 hours, preferably 30 minutes to 5 hours. After the reaction, a free flowing and smooth catalyst can be obtained by a method of removing the solvent under reduced pressure or a method of separating by filtration.

In producing the ethylene polymer of the present invention using the above-mentioned catalyst, a liquid phase polymerization method such as slurry polymerization or solution polymerization, or a gas phase polymerization method can be employed. The liquid phase polymerization method is usually carried out in a hydrocarbon solvent.As the hydrocarbon solvent, a single or mixture of inert hydrocarbons such as propane, butane, isobutane, hexane, heptane, cyclohexane, benzene, toluene and xylene is used. Can be

In the gas phase polymerization method, in the presence of an inert gas,
A commonly known polymerization method such as a fluidized bed and a stirring bed can be employed, and a so-called condensing mode in which a medium for removing polymerization heat coexists in some cases can be employed. The polymerization temperature in the liquid or gas phase polymerization is generally from 0 to 300C, and practically from 20 to 200C. The catalyst concentration and the ethylene pressure in the reactor may be any concentrations and pressures as long as they are sufficient for the polymerization to proceed. Further, hydrogen or the like can coexist in the polymerization system for controlling the molecular weight.

Further, if necessary, together with ethylene,
Propylene, 1-butene, 1-hexene, 4-methyl-
Α-olefins such as 1-pentene and 1-octene may be copolymerized alone or by introducing two or more kinds into the reactor. The content of α-olefin in the obtained copolymer is desirably 10 mol% or less, preferably 5 mol% or less.

By carrying out the method of the present invention, the number average molecular weight (Mn) is 2,000-20,000, the weight average molecular weight (Mw) is 200,000-600,000, and Mw / Mn is 30-8.
0, an ethylene polymer having a wide molecular weight distribution, excellent impact resistance and environmental stress cracking resistance, and free from melt fracture can be obtained.

[0033]

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 addition, the physical properties (molecular weight, molecular weight distribution, melt flow rate, density, die swell ratio, tensil impact, ESCR) of the polymers obtained in Examples and Comparative Examples were measured by the following methods.

A) Molecular weight and molecular weight distribution Gel permeation chromatography (GPC) was performed on the produced ethylene polymer under the following conditions, and the number average molecular weight (M
n) and the weight average molecular weight (Mw) were determined. Gel permeation chromatography measurement conditions: Apparatus: WATERS 150C model, Column: Shodex-HT806M, Solvent: 1,2,4-trichlorobenzene, Temperature: 135 ° C, Sample concentration: 2mg / 5ml, Universal using monodisperse polystyrene fraction Rating. Regarding the molecular weight distribution represented by the ratio of Mw to Mn (Mw / Mn) (the larger the Mw / Mn, the wider the molecular weight distribution), see “Size Exclusion Chromatography (High-Performance Liquid Chromatography of Polymers)”, Sadao Mori, The equation of molecular weight and detector sensitivity described in Kyoritsu Shuppan, p.
The data of the alkane and the fractionated linear polyethylene having Mw / Mn ≦ 1.2 were applied to determine the sensitivity of the molecular weight M represented by the following formula, and the measured value of the sample was corrected.

## EQU1 ## Sensitivity of molecular weight M = a + b / M (a and b are constants, a = 1.032, b = 189.2)

B) Melt flow rate According to Table 7, condition 7 of JIS K-7210 (1996 version), the measured value at a temperature of 190 ° C. and a load of 21.6 Kgf was expressed as H
Shown as LMFR. c) Density Measured according to JIS K-7112 (1996 version). d) Die swell ratio (hereinafter abbreviated as SR) Using the same apparatus as for HLMFR, the value was shown as the degree of expansion (%) of the outer diameter of the extruded product with respect to the orifice diameter at the time of HLMFR measurement.

E) Tensile Impact According to ASTM D-1822, at 23 ° C and -40
Tensile impact measured at ° C was taken as the value of impact resistance. f) B measured according to ESCR JIS K-6760 (1996 version)
The F50 value by the TL method was used as the ESCR value.

Example 1 (1) Synthesis of tris (bistrimethylsilylamide) chromium (III) (Cr [N (SiMe ₃ ) ₂ ] ₃ ) described in J. Chem. Soc., (A), 1433 (1971) According to the method described, tris (bistrimethylsilylamide) chromium (II
I) was synthesized. In a 200 ml flask previously purged with nitrogen, 1.93 g (12.2 mmol) of anhydrous chromium trichloride was added, and 30 ml of tetrahydrofuran was added to form a slurry. After cooling to 0 to 3 ° C. in an ice bath, 1.0 mol / l of lithium bis (trimethylsilyl) amide (Aldri)
36.6 ml (36.6 mmol; amide / chromium molar ratio = 3) -hexane solution was added. After stirring at 25 ° C. for 4 hours to confirm that chromium trichloride had completely disappeared, the solvent was completely removed under reduced pressure. 100 ml of hexane was added to the resulting dark green mass, which was dissolved and filtered with a glass filter to remove by-product lithium chloride. The measured chromium concentration of the obtained solution was 0.12 mmol-Cr / ml.
(6.2 mg-Cr / ml).

(2) Preparation of catalyst A 300 ml flask previously purged with nitrogen was placed at 300 ° C.
3.0 g of 952 grade silica (average particle size: 80 μm, specific surface area: 300 m ² / g, pore volume: 1.6 cm ³ / g) purchased from WRGrace Corporation and calcined for 8 hours was added, and 30 ml of hexane was added to form a slurry. 0.48 ml of the chromamide solution obtained in (1) (chromium atom loading = 0.10 wt%) was added, and the mixture was stirred at 40 ° C for 1 hour.
Subsequently, 11.5 ml of a 0.5 mol / liter-hexane solution of butylethylmagnesium (manufactured by Tosoh Akzo).
(Molar ratio of magnesium / chromium = 100), and 4
Stirred at 0 ° C. for 2 hours. The solvent was removed under reduced pressure to give a free flowing catalyst.

(3) Polymerization In a 1.5 liter autoclave sufficiently purged with nitrogen, 0.6 liter of isobutane and 0.12 of the catalyst obtained in (2) were added.
g, and the internal temperature was raised to 90 ° C. Then, ethylene was injected under pressure, 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, 148 g of polyethylene was obtained. The polymerization activity per 1 g of catalyst per 1 hour of polymerization time is 1230 g / g · h
r. The molecular weight of the obtained polyethylene, molecular weight distribution, melt flow rate, density, die swell ratio,
Table 1 shows the measurement results of Tensile Impact and ESCR
Shown in

Example 2 In Example 1 (2), 11.5 ml of a 0.5 mol / l-heptane solution of dibutylmagnesium (manufactured by Tosoh Akzo) in place of butylethylmagnesium was used.
A catalyst was prepared and polymerized in the same manner as in Example 1 except that (magnesium / chromium molar ratio = 100) was added. As a result, 157 g of polyethylene was obtained.
The polymerization activity per 1 g of catalyst and the polymerization time per hour was 13
It was 10 g / g · hr. Table 1 shows the measurement results of physical properties of polyethylene.

Example 3 In Example 1 (2), the addition amount of the chromamide solution was 0.96 ml (chromium atom carrying amount = 0.20 wt%), and the addition amount of butylethylmagnesium was 23.0 ml (magnesium / chromium molar ratio = 100). Example 1 except for (1)
A catalyst was prepared and polymerized in the same manner as described above. As a result, 2
23 g of polyethylene were obtained. The polymerization activity per 1 hour of the polymerization time per 1 g of the catalyst was 1,860 g / g · hr. Table 1 shows the measurement results of physical properties of polyethylene.

Example 4 In Example 1 (2), the amount of butylethylmagnesium added was 5.8 ml (magnesium / chromium molar ratio = 5
A catalyst was prepared and polymerization was carried out in the same manner as in Example 1 except that 0) was used. As a result, 142 g of polyethylene was obtained. The polymerization activity per 1 g of the catalyst per 1 hour of the polymerization time was 1,180 g / g · hr. Table 1 shows the measurement results of physical properties of polyethylene.

Example 5 In Example 1 (2), instead of 952 grade silica, C (manufactured by Fuji Silysia Co.) fired at 300 ° C. for 8 hours.
ARiACT P-3 grade silica (average particle size 35
μm, specific surface area 720 m ² / g, pore volume 1.2 cm ³ /
A catalyst was prepared and polymerized in the same manner as in Example 1 except that g) was used. As a result, 169 g of polyethylene was obtained. The polymerization activity per 1 g of the catalyst and 1 hour of the polymerization time was 14,10 g / g · hr. Table 1 shows the measurement results of physical properties of polyethylene.

Example 6 (1) Tris (diisopropylamide) chromium (III)
Synthesis of (Cr [N (CHMe ₂ ) ₂ ] ₃ ) 1.93 g (12.2 mmol) of anhydrous chromium trichloride was placed in a 200 ml flask previously replaced with nitrogen, and 30 ml of tetrahydrofuran was added to form a slurry. 0-3 ° C in an ice bath
After cooling to lithium diisopropylamide (Aldri
ch) was dissolved in tetrahydrofuran to give 1.0 mol /
36.6 ml (36.6 mmol; amide /
Chromium molar ratio = 3) was added. After stirring at 25 ° C. for 4 hours to confirm that chromium trichloride had completely disappeared, the solvent was completely removed under reduced pressure. Hexane 1
The mixture was dissolved by adding 00 ml, and filtered by a glass filter to remove by-product lithium chloride. When the chromium concentration of the obtained solution was measured, it was 0.10 mmol-Cr / ml.
(5.2 mg-Cr / ml).

(2) Preparation and polymerization of catalyst In Example 1 (2), instead of tris (bistrimethylsilylamide) chromium (III), tris (diisopropylamido) chromium (III) obtained in the above (1) was used.
0.58 ml of hexane solution (chromium atom loading = 0.10 wt
%), And a catalyst was prepared and polymerized in the same manner as in Example 1 except that% was added. As a result, 130 g of polyethylene was obtained. The polymerization activity per 1 g of the catalyst and per one hour of the polymerization time was 1080 g / g · hr. Table 1 shows the measurement results of physical properties of polyethylene.

Example 7 (1) Preparation of Catalyst A 100 ml flask previously purged with nitrogen was placed at 300 ° C.
8 hours CARiACT P manufactured by Fuji Silysia
-3 grade silica (average particle size 35 μm, specific surface area 7
3.0 g of 20 m ² / g, pore volume 1.2 cm ³ / g) and 18.3 mg of anhydrous chromium trichloride (chromium atom carrying amount = 0.20 wt)
%), And 30 ml of tetrahydrofuran was added to form a slurry. While stirring at 25 ° C., 1.0 mol / l of lithium bis (trimethylsilyl) amide (Aldr
ich) -hexane solution 0.35 ml (0.35 mmol;
Amide / chromium molar ratio = 3) was added. After stirring at 25 ° C. for 2 hours, the solvent was completely removed under reduced pressure to obtain a solid component. Subsequently, 30 ml of hexane was added to obtain a slurry. Butylethylmagnesium (Tosoh Akzo)
Was added and 23.0 ml of a 0.5 mol / l-hexane solution (magnesium / chromium molar ratio = 100) was added thereto, followed by stirring at 40 ° C. for 2 hours. The solvent was removed under reduced pressure to give a free flowing free flowing catalyst.

(2) Polymerization Polymerization was carried out in the same manner as in Example 1 except that the catalyst obtained in the above (1) was used. As a result, 141 g of polyethylene was obtained. The polymerization activity per 1 g of the catalyst per 1 hour of the polymerization time was 1,180 g / g · hr. Table 1 shows the measurement results of physical properties of polyethylene.

Example 8: Gas-phase polymerization A vertical vibration reactor similar to that described in Eur. Polym. J., Vol. 21, 245 (1985), which resembles a fluidized bed reactor (capacity 150 cm ³ , A gas phase polymerization was carried out at a diameter of 50 mm, a vibration speed of 420 times / min (7 Hz) and a vibration distance of 6 cm). A reactor in which 100 mg of the catalyst obtained in Example 1 (2) was sealed in an ampoule under a nitrogen atmosphere was placed in a reactor previously purged with nitrogen, heated to 87 ° C., and then heated to 5 kg / cm ^2.
After injecting ethylene, the polymerization was started by starting vibration and breaking the ampoule. Ethylene was fed as needed via flexible joints to maintain the ethylene pressure in the reactor. After the polymerization reaction was carried out at 90 ° C. for 1 hour, ethylene feeding was stopped, the reactor was cooled to room temperature, degassed, and the contents were taken out.
As a result, 40 g of polyethylene was obtained. 1g of catalyst
Per hour, polymerization activity per hour of polymerization time is 400 g /
g · hr. Table 1 shows the measurement results of the physical properties of polyethylene.
Shown in

Example 9 In the polymerization of Example 1 (3), hydrogen was added at 3 kg / cm ^2.
Except for the introduction, polymerization was carried out in the same manner as in Example 1. As a result, 138 g of polyethylene was obtained. The polymerization activity per 1 g of catalyst per 1 hour of polymerization time is 1150
g / g · hr. Table 1 shows the measurement results of physical properties of polyethylene.

Example 10 In the polymerization of Example 1 (3), 10 ml of 1-hexene was used.
Was polymerized in the same manner as in Example 1 except that ethylene was introduced under pressure and copolymerization was performed. As a result, 156
g of polyethylene were obtained. The polymerization activity per 1 g of the catalyst per 1 hour of the polymerization time was 1,300 g / g · hr. Table 1 shows the measurement results of physical properties of polyethylene.

Comparative Example 1 As a so-called Phillips catalyst in which chromium trioxide was supported on silica, a Philips catalyst 9 purchased from WR Grace Corporation
A 69ID catalyst (chromium atom carrying amount = 1.0 wt%) was fired in air at 600 ° C for 30 hours, and the polymerization conditions were all set to 100 ° C, except that the polymerization temperature was 100 ° C. Polymerization was performed. As a result, 144 g of polyethylene was obtained. The polymerization activity per 1 hour of the polymerization time per 1 g of the catalyst was 1200 g / g · hr. Table 1 shows the measurement results of physical properties of polyethylene. It can be seen that the molecular weight distribution is narrower than in Examples 1 to 10 and the ESCR is very low.

Comparative Example 2 (1) Bis (triphenylsilyl) chromate (CrO
Synthesis of ₂ (OSiPh ₃ ) ₂ ) Bis (triphenylsilyl) chromate was synthesized by reacting chromium trioxide with triphenylsilanol according to the method described in US Pat. No. 2,863,891.

(2) Preparation of Catalyst A 500 ml flask previously purged with nitrogen was placed at 500 ° C.
3.0 g of 952 grade silica (average particle size: 80 μm, specific surface area: 300 m ² / g, pore volume: 1.6 cm ³ / g) purchased from WRGrace Corporation and calcined for 6 hours in
Hexane (30 ml) was added to form a slurry. 0.1 mol of bis (triphenylsilyl) chromate obtained in (1)
1 / liter-hexane solution 1.15 ml (chromium atom carrying amount = 0.20 wt%) was added, and the mixture was stirred at 25 ° C. for 1 hour.
Subsequently, 0.96 ml of a 1.2 mol / l-hexane solution of triethylaluminum (manufactured by Tosoh Akzo)
(Aluminum / chromium molar ratio = 10) and 25
Stirred at C for 1 hour. The solvent was removed under reduced pressure to give a free flowing free flowing catalyst.

(3) Polymerization Polymerization was carried out in the same manner as in Example 1 except that the catalyst obtained in the above (2) was used. As a result, 150 g of polyethylene was obtained. The polymerization activity per 1 g of the catalyst per 1 hour of the polymerization time was 1250 g / g · hr. Table 1 shows the measurement results of physical properties of polyethylene. Although the molecular weight distribution was wide and the ESCR was higher than that of Comparative Example 1, the tensile impact was low, and the extrudate at the time of HLMFR measurement caused melt fracture, and SR could not be measured.

Comparative Example 3 (1) Bis (bistrimethylsilylamide) chromium (I
I) -THF complex (Cr [N (SiMe ₃ ) ₂ ] ₂ (TH
F) Synthesis of ₂ ) Bis (bistrimethylsilylamide) chromium (II) -THF complex was synthesized according to the method described in Z.anorg.allg.Chem., 457, 38 (1979).

(2) Preparation of catalyst In Example 1 (2), instead of tris (bistrimethylsilylamide) chromium (III), bis (bistrimethylsilylamide) chromium (I) obtained in the above (1) was used.
I) 0.96 ml of a 0.060 mol / liter-hexane solution of -THF complex (chromium atom loading = 0.10 wt%) was added. After the loading reaction of the chromamide compound, a solid component was prepared in the same manner as in Example 1 except that drying was performed under reduced pressure without performing a reaction with butylethylmagnesium.

(3) Polymerization All of the examples were prepared except that 0.12 g of the solid component obtained in (2) and 1.0 ml of a 1.0 mol / l-hexane solution of triethylaluminum (manufactured by Tosoh Akzo) were added to the autoclave. Polymerization was carried out in the same manner as in Example 1. As a result, 26 g of polyethylene was obtained. The polymerization activity per 1 g of the catalyst and the polymerization time per hour is 220 g / g.
Hr. Table 1 shows the measurement results of physical properties of polyethylene. The polymerization activity is remarkably low as compared with the case of using a trisamide derivative composed of trivalent chromium atoms and butylethylmagnesium, and the tensil impact is also low.

Comparative Example 4 Example 1 (2) was repeated except that a 1.2 mol / L-hexane solution of triisobutylaluminum (manufactured by Tosoh Akzo) was added instead of butylethylmagnesium. Similarly, a catalyst was prepared and polymerization was carried out. As a result, 2 g of polyethylene was obtained. The polymerization activity per 1 g of the catalyst and 1 hour of the polymerization time was 17 g / g · hr. The polymerization activity was significantly lower than when butylethylmagnesium was used. Physical properties could not be measured due to low polymer yield.

Comparative Example 5 In Example 1 (2), 952 grade calcined at 600 ° C. was used instead of 952 grade silica calcined at 300 ° C.
0.96m of chromamide solution using grade silica
1 (chromium atom loading = 0.20 wt%), 23.0 ml of 0.5 mol / l-hexane solution of butylethylmagnesium (magnesium / chromium molar ratio = 100),
A catalyst was prepared and polymerized in the same manner as in Example 1 except that each was added. As a result, only 1.0 g of polyethylene was obtained although ethylene was consumed throughout the polymerization reaction. Only the solvent after the completion of the polymerization reaction was sampled and subjected to gas chromatography analysis. As a result, it was found that 45 g of 1-hexene was produced. The polymerization activity per 1 g of the catalyst per 1 hour of the polymerization time was 8 g / g · hr. The polymerization activity was significantly lower than that of silica calcined at 300 ° C., and instead, 1-hexene, a trimer of ethylene, was the main product. Physical properties could not be measured due to low polymer yield.

Comparative Example 6 In Example 1 (2), Comparative Example 3 (1) was used instead of tris (bistrimethylsilylamide) chromium (III).
The same procedure as in Example 1 was performed, except that 0.96 ml of a 0.060 mol / liter-hexane solution of bis (bistrimethylsilylamide) chromium (II) -THF complex obtained in the above (chromium atom carrying amount = 0.10 wt%) was added. A catalyst was prepared and polymerization was performed. As a result, 21 g of polyethylene was obtained. The polymerization activity per 1 hour of the polymerization time per 1 g of the catalyst was 180 g / g · hr. The polymerization activity is remarkably low as compared with the case where a trisamide derivative comprising a trivalent chromium atom is used. Table 1 shows the measurement results of physical properties of polyethylene. The values of SR and Tensile Impact are lower than in the case where a trisamide compound comprising a trivalent chromium atom is used.

The results of the above Examples and Comparative Examples are shown in a table.

[Table 1]

[0062]

According to the method of the present invention, a high-quality ethylene-based material suitable for film and blow molding, which has a wide molecular weight distribution, excellent impact resistance and environmental stress cracking resistance, does not cause melt fracture, and is suitable for film molding and blow molding. The union can be efficiently and industrially advantageously produced.

[Brief description of the drawings]

FIG. 1 is a flowchart of the preparation of a catalyst used in the method for producing an ethylene polymer of the present invention.

Claims (5)

[Claims] An amide compound of a trivalent chromium atom, 100
A method for producing an ethylene-based polymer, comprising using a catalyst comprising an inorganic oxide solid and an organomagnesium compound calcined at a temperature of from 500 to 500 ° C. 2. The method for producing an ethylene polymer according to claim 1, wherein an inorganic oxide solid calcined at 200 to 450 ° C. is used. 3. The method for producing an ethylene-based polymer according to claim 1, wherein a catalyst obtained by supporting an amide compound of a trivalent chromium atom on an inorganic oxide solid and reacting the amide compound with an organomagnesium compound is used. 4. The method for producing an ethylene-based polymer according to claim 1, wherein the ethylene-based polymer is polyethylene. 5. The method for producing an ethylene polymer according to claim 1, wherein the ethylene polymer is a copolymer of ethylene and an α-olefin.