JPH11228623A - Production of ethylene-based polymer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for efficiently producing an ethylene-based polymer with relatively high molecular weight, broad molecular weight distribution, excellent environmental stress cracking resistance, drawdown resistance, impact resistance and low ultra-low molecular weight components, and suitable for e.g. blow-molded products. SOLUTION: This method for producing an ethylene-based polymer with an HLMFR (in the present invention, the measurement determined in accordance with the requirements 7 in Table 1 in the JIS K-7210 at 190 deg.C under a load of 21.6 kgf) of 0.1-20 g/10 min and density of 0.930-0.980 g/cm<3> comprises using a catalyst composed of an organic group-bearing chromium compound, a carrier and an activator; wherein the polymer formed is washed with a solvent and then separated from the solvent through filtration or centrifugation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing an ethylene polymer. More specifically, polymerization is carried out using a catalyst composed of a chromium compound having an organic group, a carrier and an activator, and the resulting polymer is washed with a solvent, and then separated by filtration or centrifugation to obtain an environmental stress crack (ESCR). The present invention relates to a method for producing an ethylene-based polymer which is excellent in drawdown resistance and impact resistance and which is particularly suitable for large-sized blows, such as blows having a small amount of extremely low molecular weight components.

[0002]

2. Description of the Related Art Ethylene-based polymers are generally and widely used as resin materials for various molded articles, but required characteristics differ 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, but a product having a relatively high molecular weight is suitable for a product molded by inflation molding or blow molding. Polymers having a wide molecular weight distribution are suitable. It has been known that an ethylene polymer having a wide molecular weight distribution suitable for blow molding or the like can be obtained by using a so-called Phillips catalyst in which chromium trioxide is supported on an inorganic oxide such as silica. Further, JP-A-2-123108, JP-A-4-123108
18407, one-stage or multi-stage polymerization using a Ziegler catalyst disclosed in JP-A-5-230136, etc.
An ethylene polymer having a wide molecular weight distribution suitable for blow molding or the like can be obtained.

[0003] However, in recent years, demands for large blow molding such as gasoline tanks and large drums have been increasing, and there has been a demand for a higher quality ethylene raw material suitable for this. When an ethylene-based polymer having a wide molecular weight distribution obtained by the above-mentioned conventional catalyst or the like is used to produce a blow-molded product, the molded product is: (1) The environmental stress cracking (ESCR) is insufficient. Absent. (2) Regarding the moldability, since the drawdown resistance of the parison at the time of blow molding is not sufficient, the thickness distribution of the molded product becomes uneven. It is not always satisfactory in any of these points.

[0004] For this reason, many new catalyst systems have been proposed for the production of ethylene polymers for blow molding. For example, Japanese Patent Publication No. 7-503739 discloses a method for obtaining an ethylene polymer having a wide molecular weight distribution by using a catalyst comprising a chromium compound and alumoxane. However, it is difficult to say that the ethylene polymer obtained by this method has a sufficient level of both the environmental stress cracking (ESCR) resistance and the drawdown resistance, and the impact resistance is not sufficient.
Problems remain, such as the generation of smoke during molding and a large amount of extremely low-molecular-weight components that cause scumming. Also, JP-A-2-105
806 and JP-A-2-185506 disclose a solid catalyst component in which chromium trioxide or a chromium compound that forms at least partially chromium oxide upon firing is supported on an inorganic oxide carrier, and alumoxane, organic aluminum alkoxide or organic aluminum siloxide. A method for obtaining an ethylene polymer having a wide molecular weight distribution by using a catalyst comprising However, the ethylene-based polymer obtained by these methods also has an environmental stress crack resistance (ESC).
R) and drawdown resistance are not at a sufficient level, and furthermore, the impact resistance is not sufficient, and the amount of extremely low molecular weight components that cause smoke and mold during molding is large.

Further, Japanese Patent Publication No. Sho 44-2996 and Japanese Patent Publication No. Sho 44-
3827 and JP-B-47-1766 disclose a method for obtaining an ethylene polymer having a wide molecular weight distribution using a catalyst in which a chromate ester is supported on an inorganic oxide solid such as silica. However, the ethylene-based polymer obtained by these methods also has an environmental stress crack resistance (ESC).
R) and drawdown resistance are not at a sufficient level, and furthermore, the impact resistance is not sufficient, and the amount of extremely low molecular weight components that cause smoke and mold during molding is large. Japanese Patent Application Laid-Open No. 54-120290 discloses a method for obtaining an ethylene polymer having a wide molecular weight distribution by using a catalyst comprising alumoxane and a solid component treated with an organoaluminum alkoxide after supporting a chromate ester on silica.
However, the ethylene polymers obtained by these methods also have insufficient levels of environmental stress cracking (ESCR) resistance and drawdown resistance, and also have insufficient impact resistance. The amount of the very low molecular weight component that causes the is large. Further US Pat. No. 5,104,
No. 841, U.S. Pat. No. 5,137,997 discloses a method for obtaining an ethylene polymer having a wide molecular weight distribution using a catalyst in which a chromamide compound is supported on an inorganic oxide solid such as silica. However, the ethylene polymer obtained by this method also has an environmental stress crack resistance (ESC).
R) and drawdown resistance are not at a sufficient level, and furthermore, the impact resistance is not sufficient, and the amount of extremely low molecular weight components that cause smoke and mold during molding is large.

[0006]

SUMMARY OF THE INVENTION The present invention relates to a method for producing a polymer having a relatively high molecular weight, a broad molecular weight distribution, and a resistance to environmental stress cracking (E).
SCR), with excellent drawdown resistance and impact resistance, with a low amount of ultra-low molecular weight components, and a method for efficiently producing an ethylene-based polymer particularly suitable for large blows, such as blows. .

[0007]

Means for Solving the Problems The present inventors have made intensive studies in view of the above problems, and as a result, have carried out polymerization using a catalyst comprising a chromium compound having an organic group, a carrier and an activator, and produced The object was solved by a method for producing an ethylene-based polymer, characterized in that the coalesced product was washed with a solvent and then separated by filtration or centrifugation. That is, the present invention provides (1) HLMFR (in the present invention, at a temperature of 190 ° C. and a load of according to condition 7 of JIS K-7210 Table 1) using a catalyst comprising a chromium compound having an organic group, a carrier and an activator. The measured value at 21.6 kgf is shown.) = 0.1 to 20 g / 10 min, density = 0.93
A method for producing an ethylene-based polymer, which is characterized in that, when producing an ethylene-based polymer of 0 to 0.980 g / cm ³ , the produced polymer is washed with a solvent and then separated by filtration or centrifugation;

(2) The method for producing an ethylene-based polymer according to the above (1), wherein a chromium compound having an organic group is supported on a carrier, and the catalyst is treated with an activating agent.
(3) The production of the ethylene polymer according to the above (1) or (2), wherein the chromium compound having an organic group is selected from a chromium carboxylate, a chromium-1,3-diketo compound, a chromate ester, and a chromamide compound. Method, (4)
(5) The method for producing an ethylene-based polymer according to the above (1) or (2), wherein the carrier is an inorganic metal oxide and / or an inorganic halide. (5) The carrier of the inorganic metal oxide has a specific surface area of 50 to 1000 m ^2. / G, pore volume of 0.5-3.
The above (4), which is a catalyst having 0 cm ³ / g and an average particle diameter of 10 to 200 μm and having a chromium compound having an organic group supported thereon as a chromium atom in an amount of 0.05 to 5.0 wt% based on the weight of the carrier. Description of the method for producing an ethylene polymer,
And (6) by developing the method for producing an ethylene-based polymer according to the above (1) or (2), wherein the activator is selected from an organic lithium compound, an organic magnesium compound, an organic aluminum compound, and an organic boron compound. The goal was achieved.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be specifically described below. As the chromium compound having an organic group used in the present invention, a chromium carboxylate, a chromium-1,3-diketo compound, a chromate ester, and a chromamide compound are suitable. As the chromium carboxylate, chromium (II) or chromium (III) represented by the general formula (1) or (2)
The compound of.

[0010]

Embedded image

Embedded image (R ¹ , R ² and R ³ , R ⁴ , R ⁵ are hydrogen or a hydrocarbon group in which at least one of each of the general formulas is a hydrocarbon group having 1 to 18 carbon atoms. May be different.)

Specific examples include chromium (II) formate, chromium (II) acetate, chromium (II) propionate, chromium (II) butyrate, chromium (II) pentanoate, chromium (II) hexanoate, and 2-ethyl Chromium (II) hexanoate, chromium (II) benzoate, chromium (II) naphthenate, chromium (II) oleate, chromium oxalate (II), chromium formate (II)
Chromium (III) acetate, chromium (III) propionate, chromium (III) butyrate, chromium (III) pentanoate, chromium (III) hexanoate, chromium (III) 2-ethylhexanoate, chromium benzoate ( III), chromium (III) naphthenate, chromium (III) oleate, chromium oxalate (III), among which chromium acetate (II), chromium (II) 2-ethylhexanoate, chromium (III) acetate ) And chromium (III) 2-ethylhexanoate are preferred.

As the chromium-1,3-diketo compound,
A chromium (III) complex represented by the general formula (3) and having one to three 1,3-diketo compounds. _{CrX k Y m Z n (3} ) (X is a 1,3-diketo type chelate ligand, Y and Z is halogen, alkoxy, aryloxy, alkyl, aryl, selected from amides, be the same (K + m + n = 3, 1 ≦ k ≦ 3). Specific examples include chromium-1,3-butanedionate,
Chromium acetylacetonate, chromium-2,4-hexanedionate, chromium-2,4-heptanedionate,
Chromium-2,4-octandionate, chromium-3,5
Octandionate, chromium benzoylacetonate, chromium-1,3-diphenyl-1,3-propanedionate, chromium-2-methyl-1,3-butanedionate, chromium-2-ethyl-1,3- Butanedionate, chromium-2-phenyl-1,3-butanedionate, chromium-1,2,3-triphenyl-1,3-propanedionate and the like can be mentioned, among which chromium acetylacetonate is preferable.

The chromic ester is represented by the general formula (4)
Is a compound of chromium (VI) represented by

Embedded image (R ⁶ , R ⁷ , R ⁸ , R ⁹ , R ¹⁰ , and R ¹¹ each have 1 carbon atom.
To 18 hydrocarbon groups, which may be the same or different. M ¹ and M ² each represent a carbon atom or a silicon atom. As specific examples, when M ¹ and M ² are carbon, bis (tert-butyl) chromate, bis (1,1-dimethylpropyl) chromate, bis (1-methyl-1-phenylethyl) chromate, bis ( 1,1-diphenylethyl) chromate, bis (triphenylmethyl) chromate, bis (1,1,2,2-tetramethylpropyl) chromate, bis (1,1,2-trimethylpropyl) chromate and the like, Especially the screw (ter)
(t-Butyl) chromate is preferred.

When M ¹ and M ² are silicon, bis (trimethylsilyl) chromate, bis (triethylsilyl) chromate, bis (tributylsilyl) chromate, bis (triisopentylsilyl) chromate, bis (tri-2-yl) chromate Ethylhexylsilyl) chromate, bis (tridecylsilyl) chromate, bis (tri (tetradecyl) silyl) chromate, bis (tribenzylsilyl) chromate, bis (triphenethylsilyl) chromate, bis (triphenylsilyl) chromate, bis (tri) Tolylsilyl) chromate, bis (trixylylsilyl) chromate, bis (trinaphthylsilyl) chromate, bis (dimethylphenylsilyl) chromate,
Bis (diphenylmethylsilyl) chromate, bis (dimethyltexylsilyl) chromate, bis (dimethylisopropylsilyl) chromate, bis (tert-butyldimethylsilyl) chromate, bis (tri-tert)
-Butylsilyl) chromate, bis (triethylphenylsilyl) chromate, bis (trimethylnaphthylsilyl) chromate, polydiphenylsilylchromate, polydiethylsilylchromate and the like, with bis (triphenylsilyl) chromate being preferred.

Examples of the chromamide compound include chromium (II) or chromium (III) represented by the general formula (5) or (6).

Embedded image (R ¹² , R ¹³ , R ¹⁴ , R ¹⁵ , R ¹⁶ , R ¹⁷ , R ¹⁸ , R ¹⁹ ,
At least one of R ²⁰ , R ²¹ , R ²² , and R ²³ is hydrogen or a hydrocarbon group having 1 to 18 carbon atoms, and may be the same or different. M ³ ,
M ⁴ , M ⁵ , and M ⁶ are carbon and / or silicon atoms, L ¹
Represents a ligand such as ether or nitrile, and 0 ≦
p ≦ 2. )

[0016]

Embedded image (R ²⁴ , R ²⁵ , R ²⁶ , R ²⁷ , R ²⁸ , R ²⁹ , R ³⁰ , R ³¹ ,
^R32 , ^R33 , ^R34 , ^R35 , ^R36 , ^R37 , ^R38 , ^R39 , R
^And at least one of R ⁴¹ has 1 to 18 carbon atoms.
Hydrogen or a hydrocarbon group, which may be the same or different. ^{M 7, M 8, M 9} , M
¹⁰ , M ¹¹ and M ¹² are carbon and / or silicon atoms. )

As specific examples, bis (bistrimethylsilylamide) chromium (II) -THF complex, bis (bistrimethylsilylamide) chromium (II) -diethyl ether complex, bis (methyltrimethylsilylamide) chromium (II) -THF complex , Bis (methyltrimethylsilylamide) chromium (II) -diethyl ether complex, bis (t
tert-butyltrimethylsilylamide) chromium (II)
-THF complex, bis (tert-butyltrimethylsilylamide) chromium (II) -diethyl ether complex, bis (phenyltrimethylsilylamide) chromium (II) -T
HF complex, bis (phenyltrimethylsilylamide) chromium (II) -diethyl ether complex, tris (dimethylamido) chromium (III), tris (diethylamido) chromium (III), tris (diisopropylamido) chromium (I)
II), tris (methylphenylamide) chromium (III),
Tris (diphenylamide) chromium (III), tris (bistrimethylsilylamide) chromium (III), tris (bistriethylsilylamide) chromium (III), tris (bistriphenylsilylamide) chromium (III) and the like.

The carrier used in the present invention is a particulate solid, and is preferably a solid in a polymerization medium.
Porous is particularly preferred. Specifically, inorganic metal oxides,
Inorganic halides, inorganic hydroxides, inorganic carbonates, inorganic phosphates, inorganic compounds such as inorganic sulfates, polyethylene,
Copolymer of polypropylene, polystyrene, or olefins such as ethylene, propylene, and styrene with polar group-containing monomers such as acrylic acid, acrylic ester, methacrylic acid, methacrylic ester, vinyl ether, acrylonitrile, allyl alcohol, and vinyl acetate Is used. Among them, an inorganic metal oxide carrier and an inorganic halide are preferred.

As the inorganic metal oxide carrier, oxides of Groups 2, 4, 13, and 14 of the periodic table are preferable. Specifically, magnesia, titania, zirconia, alumina, silica, thoria, aluminum phosphate, Silica-titania, silica-zirconia, silica-alumina or mixtures thereof. Here, aluminum phosphate is formally a phosphate, but is classified as an oxide because of its properties as an oxide. The surface area of these inorganic metal oxide supports is 50 to 1000 m ² / g, preferably 200 m ² / g.
８００800 m ² / g, pore volume is 0.5-3.0 cm ³ / g
g, preferably 1.0 to 2.5 cm ³ / g, and the average particle size is 10 to 200 μm, preferably 30 to 150 μm. As these inorganic metal oxides, those obtained by firing at a temperature of 100 to 900 ° C. for 10 minutes to 24 hours under a stream of dry nitrogen gas under a molecular sieve stream are preferably used. The calcination is preferably carried out in a solid fluid state with a sufficient amount of nitrogen gas. In addition, a known method of adding a titanate, a fluorine-containing salt, or the like and firing the mixture may be used in combination. The inorganic halide is a halide of a metal belonging to Group 2 or 13 of the periodic table, such as magnesium chloride, magnesium bromide,
Examples thereof include magnesium iodide, calcium chloride, aluminum chloride, gallium chloride, and mixtures thereof.

In the present invention, as the activator, an organometallic compound, particularly an organometallic compound belonging to Group 1, 2, or 13 of the periodic table, specifically, an organolithium compound, an organomagnesium compound, an organoaluminum compound, Organic boron compounds are preferably used. Examples of the organic lithium compound include an alkyl lithium or cycloalkadienyl lithium compound, specifically, methyl lithium, ethyl lithium, n-butyl lithium, sec-butyl lithium, tert-butyl lithium, cyclopentadienyl lithium, indenyl. Lithium, fluorenyllithium and the like can be mentioned, among which methyllithium and n-butyllithium are preferable.

Examples of the organomagnesium compound include dialkylmagnesium, alkylmagnesium alkoxide and alkylmagnesium halide compounds. Specific examples thereof include butylethylmagnesium, dibutylmagnesium, ethylmagnesium methoxide, ethylmagnesium ethoxide, and ethylmagnesiumisomethoxide. Propoxide, ethyl magnesium n-butoxide, ethyl magnesium isobutoxide, ethyl magnesium phenoxide, butyl magnesium methoxide, butyl magnesium ethoxide, butyl magnesium isopropoxide, butyl magnesium n-butoxide, butyl magnesium isobutoxide, butyl magnesium phenoxide, methyl Magnesium chloride, ethyl magnesium chloride , N- butylmagnesium chloride, phenylmagnesium chloride, methyl magnesium bromide, ethyl magnesium bromide, n-
Examples thereof include butylmagnesium bromide and phenylmagnesium bromide. Among them, butylethylmagnesium, ethylmagnesium ethoxide, ethylmagnesium isopropoxide, ethylmagnesium n-butoxide, and ethylmagnesium isobutoxide are preferable.

Examples of the organoaluminum compound include trialkylaluminum, dialkylaluminum halide, dialkylaluminum alkoxide, alkylaluminum dihalide, alkylaluminum dialkoxide, dialkylaluminum hydride, alumoxane, siloxyalane and the like. Of the organoaluminum compounds, alumoxanes are particularly preferred. Specific examples of trialkylaluminum include trimethylaluminum, triethylaluminum, tri-n-butylaluminum, triisobutylaluminum, trihexylaluminum, trioctylaluminum and the like, among which trimethylaluminum, triethylaluminum and triisobutylaluminum are preferable. .

Specific examples of the dialkylaluminum halide include dimethylaluminum chloride, diethylaluminum chloride and diisobutylaluminum chloride. Of these, diethylaluminum chloride is preferable. Specific examples of the dialkyl aluminum alkoxide include dimethyl aluminum methoxide, dimethyl aluminum ethoxide, dimethyl aluminum isopropoxide, and dimethyl aluminum n-
Butoxide, dimethyl aluminum isobutoxide, diethyl aluminum ethoxide, diethyl aluminum isopropoxide, diethyl aluminum n-butoxide, diethyl aluminum isobutoxide, diisobutyl aluminum ethoxide, diisobutyl aluminum isopropoxide, diisobutyl aluminum n-butoxide, diisobutyl aluminum isobutoxide And di-n-hexylaluminum ethoxide, di-n-hexylaluminum isopropoxide, di-n-hexylaluminum n-butoxide, di-n-hexylaluminum isobutoxide and the like, and among them, diethylaluminum ethoxide is preferable. Specific examples of the alkylaluminum dihalide include methylaluminum dichloride, ethylaluminum dichloride, isobutylaluminum dichloride and the like, and among them, ethylaluminum dichloride is preferable.

Specific examples of the alkylaluminum dialkoxide include methylaluminum dimethoxide, methylaluminum diethoxide, methylaluminum diisopropoxide, methylaluminum di-n-butoxide, methylaluminum diisobutoxide, ethylaluminum diethoxide, Ethylaluminum diisopropoxide, ethylaluminum di-n-butoxide, ethylaluminum diisobutoxide, isobutylaluminum diethoxide, isobutylaluminum diisopropoxide, isobutylaluminum di-n-butoxide,
Isobutyl aluminum diisobutoxide, n-hexyl aluminum diethoxide, n-hexyl aluminum diisopropoxide, n-hexyl aluminum di n
-Butoxide, n-hexylaluminum diisobutoxide and the like, among which ethylaluminum diethoxide is preferable. Specific examples of the dialkylaluminum hydride include dimethylaluminum hydride, diethylaluminum hydride, di-n-butylaluminum hydride, diisobutylaluminum hydride, di-n-hexylaluminum hydride, and among them, diethylaluminum hydride is preferable.

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 is represented by the following general formula (7)
Or the compound represented by (8) is mentioned.

Embedded image

Embedded image (R ⁴² is a methyl group, an ethyl group, a propyl group, n- butyl group, a hydrocarbon group such as an isobutyl group, preferably, 100 to .q 1 is a methyl group, an isobutyl group
And is preferably 4 or more, particularly preferably 8 or more. )

The preparation of this type of compound is 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 of the method include a method of producing a suspension of an inert hydrocarbon solvent by adding a trialkylaluminum, and a method of allowing solid, liquid or gaseous water to act on a trialkylaluminum in a hydrocarbon solvent. it can.

Further, an alumoxane represented by the general formula (9) or (10) may be used.

Embedded image

Embedded image (R ⁴³ 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. Further, R ⁴⁴ 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, such as bromine, is selected from hydroxyl, exhibit different radicals from R ^43. Further, R ⁴⁴ is be the same or different May be.
r is usually an integer of 1 to 100, preferably 3 or more, and r + s is 2 to 101, preferably 6 or more. )

In the compound of the general formula (9) or (10), the (O-Al (R ⁴³ )) unit and the (O-Al
(R ⁴⁴ )) The units may be connected in blocks or may be connected regularly or irregularly at random. The method for producing such an alumoxane is the same as that for the alumoxane of the general formula (7) or (8) described above. Instead of one kind of trialkylaluminum, two or more kinds of trialkylaluminum are used, Dialkyl aluminum monohalide or dialkyl aluminum monohydride may be used.

Siloxyalane as an activator is a compound represented by the general formula (11). R ⁴⁵ R ⁴⁶ R ⁴⁷ Si—O—AlR ⁴⁸ R ⁴⁹ (11) (R ⁴⁵ , R ⁴⁶ , R ⁴⁷ , R ⁴⁸ , and R ⁴⁹ are hydrocarbon groups having 1 to 18 carbon atoms and are the same; May be different.) Specific examples include trimethyldimethylsiloxyalane,
Trimethyldiethylsiloxyalan, trimethyldiisobutylsiloxyalan, trimethyldi-n-hexylsiloxyalan, triethyldimethylsiloxyalan, triethyldiethylsiloxyalan, triethyldiisobutylsiloxyalan, triethyldin-hexylsiloxyalan, triphenyldimethylsiloxyalan, triphenyldiethylsiloxy Alane, triphenyldiisobutylsiloxyalan, triphenyldi-n-hexylsiloxyalan, and the like, among which trimethyldimethylsiloxyalan, trimethyldiethylsiloxyalan, trimethyldiisobutylsiloxyalan, trimethyldin-hexylsiloxyalan, triethyldimethylsiloxyalan, triethyldimethylsiloxyalan, triethyl Diethylsiloxyalan,
Triethyldiisobutylsiloxyalane and triethyldi-n-hexylsiloxyalane are preferred.

The siloxyalane as described above includes 1) a reaction between a silanol compound represented by the general formula R ⁴⁵ R ⁴⁶ R ⁴⁷ Si—OH and an organoaluminum compound represented by the general formula R ⁴⁸ R ⁴⁹ RAl; ) Reaction of a cyclic siloxane with an organoaluminum compound represented by the general formula R ⁴⁸ R ⁴⁹ RAl 3) synthesis by a known method by reaction of a polysiloxane with an organoaluminum compound represented by the general formula R ⁴⁸ R ⁴⁹ RAl can do. In the above reactions 1) to 3), R ^{45 to} R ⁴⁹ are represented by the general formula R
R ^{45 to} R ⁴⁹ in ⁴⁵ R ⁴⁶ R ⁴⁷ Si—O—AlR ⁴⁸ R ⁴⁹
And R is a group represented by the general formula R ⁴⁵ R ⁴⁶ R ⁴⁷ Si—O—Al
R ⁴⁸ is the same as R ^{45 to} R ⁴⁹ in R ^49, and represents a group substituted in the reaction.

Examples of the organic boron compound include trialkyl borane, dialkyl alkoxy borane, alkyl dialkoxy borane and the like. Specific examples are trimethyl borane, triethyl borane, tripropyl borane, tributyl borane, trihexyl borane, trioctyl. Borane, dimethyl methoxy borane, dimethyl ethoxy borane, dimethyl propoxy borane, dimethyl butoxy borane, diethyl methoxy borane, diethyl ethoxy borane, diethyl propoxy borane, diethyl butoxy borane, methyl dimethoxy borane, methyl diethoxy borane, methyl dipropoxy borane, methyl dimethyl Butoxyborane, ethyldimethoxyborane, ethyldiethoxyborane, ethyldipropoxyborane, ethyldibutoxyborane, phenyldimethoxy Orchid, phenyldiethoxyborane, phenyldipropoxyborane, phenyldibutoxyborane, diphenylmethoxyborane, diphenylethoxyborane, diphenylpropoxyborane, diphenylbutoxyborane, etc., among which triethylborane, tributylborane, dimethylmethoxyborane, dimethyl Ethoxyborane, dimethylpropoxyborane, dimethylbutoxyborane, diethylmethoxyborane, diethylethoxyborane, diethylpropoxyborane, and diethylbutoxyborane are preferred.

As a method for obtaining a catalyst using the above-mentioned components, a method in which a chromium compound having an organic group is supported on a carrier and then treated with an activating agent is preferable. Specifically, a) After supporting a chromium compound having an organic group on a carrier,
A method of supporting an activator, b) supporting a chromium compound having an organic group on a carrier,
A method of contacting with an activator in a polymerization reactor during polymerization, c) after supporting a chromium compound having an organic group on a carrier,
A method in which an activator is supported and further contacted with the activator in a polymerization reactor during polymerization. In the case of the method (c), the activator to be carried and the activator to be brought into contact during the polymerization may be the same or different. Further, two or more activators to be contacted at the time of loading or polymerization may be treated by a method such as separately feeding, mixing and feeding, or sequentially feeding.

The supporting reaction of each component is preferably carried out in an inert hydrocarbon solvent such as propane, butane, isobutane, pentane, hexane, heptane, cyclohexane, decane, benzene, toluene and xylene. Carrier 1
Any amount of solvent per g can be used. Further, after the supporting reaction, the supported catalyst can be separated from the solvent by a method such as removing the solvent under vacuum or separating by filtration. The amount of the chromium compound having an organic group supported on the carrier is such that the chromium atom is 0.1 to the carrier.
05-5.0 wt%, preferably 0.05-2.0 wt%
% Is preferred. The amount of the activator to be contacted at the time of loading or polymerization is preferably such that the molar ratio of metal atoms to chromium atoms in the activator is 0.5 to 100. The supporting reaction temperature of the chromium compound having an organic group or the activator is preferably 0 ° C. to the boiling point of the solvent, and the supporting reaction time is preferably 5 minutes to 24 hours.

In carrying out the method of the present invention, in order to carry out the production of an ethylene polymer using the above-mentioned catalyst,
It can be performed by a slurry polymerization method or a gas phase polymerization method. The slurry polymerization method is usually carried out in a hydrocarbon solvent, and as the hydrocarbon solvent, a single or mixture of inert hydrocarbons such as propane, butane, isobutane, hexane, cyclohexane, heptane, benzene, toluene and xylene is used. . In the gas phase polymerization method, in the presence of an inert gas, a fluidized bed, a commonly known polymerization method such as a stirred bed can be adopted, and a medium for polymerization heat removal may be used in some cases,
A so-called condensing mode can also be employed. The polymerization temperature in the slurry polymerization method or the gas phase polymerization method is generally 0 to 300 ° C, and practically 20 to 300 ° C.
It is preferably performed at 200 ° C. The catalyst concentration and ethylene pressure in the reactor may be any concentration and pressure as long as they are sufficient for the polymerization to proceed.

In the present invention, environmental stress cracking (ESC)
In order to obtain an ethylene-based polymer which is particularly suitable for large blow, such as blowing excellent in R) and drawdown resistance, it is preferable that hydrogen coexist with ethylene in the system during the polymerization reaction. The amount of hydrogen coexisting with ethylene is as follows in the case of the slurry polymerization method: 5.0 × 10 ⁻⁶ ≦ hydrogen concentration in liquid phase (wt%) / ethylene concentration in liquid phase (wt%) ≦ 5.0 × 10 ^{− 3,} more preferably, 8.0 × 10 concentration of hydrogen ^-6 ≦ liquid phase (wt%) / ethylene concentration (wt%) in the liquid phase ≦ 2.0 × 10 ^{- 3,} particularly preferably 1. 0 × 10 ^-5 hydrogen concentration of ≦ liquid phase (wt%) / ethylene concentration (wt%) in the liquid phase ≦ 1.0 × 10 ^{- 3}

In the case of the gas phase polymerization method: 5.0 × 10 ⁻⁴ ≦ hydrogen partial pressure in gas phase (Kg / cm ² ) /
Ethylene partial pressure in gas phase (Kg / cm ² ) ≦ 5.0 × 10
⁻¹ , more preferably 8.0 × 10 ⁻⁴ ≦ hydrogen partial pressure in gas phase (Kg / cm ² ) /
Ethylene partial pressure in gas phase (Kg / cm ² ) ≦ 2.0 × 10
⁻¹ , particularly preferably 1.0 × 10 ⁻³ ≦ hydrogen partial pressure in gas phase (Kg / cm ² ) /
Ethylene partial pressure (Kg / cm ² ) in gas phase ≦ 1.0 × 10
The range of ^-1 and is preferable.

When the amount of hydrogen coexisting with ethylene is less than this lower limit, environmental stress cracking (ESCR) is poor, and when it exceeds this upper limit, drawdown resistance is poor.
Further, if necessary, α-olefins such as propylene, 1-butene, 1-hexene, 4-methyl-1-pentene and 1-octene can be copolymerized alone or in a mixture of two or more α-olefins. . The α-olefin content in the obtained copolymer is not more than 15 mol%, preferably 1 mol%.
0 mol% or less is desirable.

In the present invention, the ethylene polymer obtained by the above method is washed with a solvent and then separated by filtration or centrifugation. The method of washing-filtration or washing-centrifugation is as follows: i) After the slurry polymerization, the polymer and the polymerization solvent are immediately filtered or centrifuged (in this method, the polymer is already washed by the polymerization solvent during the polymerization). ), Ii) After gas phase polymerization or after slurry polymerization with a low boiling point solvent such as propane, butane or isobutane to evaporate the solvent to obtain a polymer, the obtained polymer is further washed with a solvent, and filtered. Or centrifugation. In the methods i) and ii), the ethylene polymer after separation is dried under heating and / or flowing gas such as nitrogen.

When washing in the method ii), the solvent may be a hydrocarbon such as propane, butane, isobutane, pentane, isopentane, hexane, cyclohexane, heptane, benzene, toluene, xylene, diethyl ether, isopropyl ether, Ethers such as tetrahydrofuran, ketones such as acetone, methyl ethyl ketone and methyl isobutyl ketone, methanol, ethanol, propanol, isopropanol,
Alcohols such as butanol and isobutanol are mentioned. Particularly in the case of slurry polymerization in the method ii), the solvent used for the washing may be the solvent used for the polymerization as it is. In the method ii), the washing operation in washing-filtration or washing-centrifugation may be performed in the same polymerization reactor after polymerization, but the washing operation may be performed in another washing tank having a stirrer, a filter, a centrifuge, or the like. It is preferable to carry out the washing-filtration or washing-centrifugation operation after transferring the coalescence. In addition, as for the washing operation, "Chemical Engineering Handbook (Revised 5th Edition)"
(Chemical Engineering Association, edited by Maruzen, 1988, 707-708)
Co-current or counter-current cleaning methods, as described on page p.

In the methods i) and ii), the ratio of solvent and polymer, temperature and washing time in washing-filtration or washing-centrifugation are conditions under which washing-filtration or washing-centrifugation is sufficiently performed. Any may be used. Here, the conditions that are sufficiently carried out are that, after washing and filtration, the cyclohexane extraction carried out in the examples is carried out, and the cyclohexane extraction amount is 1.8 wt% or less, preferably 1.6 wt% or less, more preferably It means the condition to be 1.4 wt% or less. If the washing-filtration or washing-centrifugation is not carried out, the amount of extremely low molecular weight components causing smoke and mess increases, resulting in poor impact resistance. Ethylene polymers suitable for large blows, such as blows, which are excellent in environmental stress (ESCR), drawdown resistance, impact resistance, and have a small amount of extremely low molecular weight components by the above catalyst and polymer production method. Although it can be obtained, an appropriate melt flow rate (HLMFR shown by the measurement method used in the following Examples and Comparative Examples) for large blow molding of gasoline tanks, drums, pallets and the like is HLMFR = 0.1 to 20 g /
It is 10 minutes, preferably 0.5 to 18 g / 10 minutes, and more preferably 1.0 to 15 g / 10 minutes. The density (the density indicated by the measurement method used in the following Examples and Comparative Examples) is 0.930 to 0.980 g / cm ³ , preferably 0.935 to 0.975 g / cm ³ , and more preferably 0.940. is a ~0.970g / cm ^3. At a density outside this range, the balance between rigidity, environmental stress resistance (ESCR), and impact resistance is poor. That is, if the density is less than this range, the rigidity is excellent, but the environmental stress resistance (ESCR) and the impact resistance are low, and the performance of the large blow molded product is reduced.

[0041]

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. The measurement methods used in Examples and Comparative Examples are shown below. [Measurement method] a) Polymer pretreatment for physical property measurement: Plastograph (Laboplastmill ME25; manufactured by Toyo Seiki Seisaku-sho, Ltd.)
The roller shape was R608 type), and 0.2 wt% of Irganox B225 manufactured by Ciba Geigy was added as an additive, and the mixture was kneaded at 190 ° C. for 7 minutes under nitrogen. b) Melt flow rate: JIS K-7210 (19
According to Table 1 and Condition 7 of the 1996 edition), the measured value at a temperature of 190 ° C. and a load of 21.6 kgf was shown as HLMFR. c) Density: Measured according to JIS K-7112 (1996 version). d) ESCR: JIS K-6760 (1996 version)
The F50 value measured by the BTL method according to the above was used as the ESCR value.

E) Drawdown resistance: Capillograph 1C manufactured by Toyo Seiki Seisaku-sho, Ltd., inner diameter 2.095 m
The resin is extruded at 230 ° C. at an extrusion speed of 100 mm / min using an orifice having a length of 8.01 mm and an inflow angle of 180 °, and the time T60 (second) until the length of the strand reaches 60 cm is reduced to drawdown resistance. The index was used. As this value is larger, the resin is less likely to sag and the drawdown resistance is better. f) Tensile impact: Tensile impact measured at 23 ° C and -40 ° C according to ASTM D-1822 was taken as the value of impact resistance. g) Amount of cyclohexane extraction: After washing and filtration, 5 g of the polymer powder dried under reduced pressure was precisely weighed, placed in a cylindrical filter paper, and extracted with boiling cyclohexane for 6 hours by a Soxhlet extractor. After extraction, the polymer powder was dried under reduced pressure and weighed accurately, and the weight loss was defined as the amount of cyclohexane extracted. This was defined as the amount of the very low molecular weight component.

Example 1 (1) Preparation of Catalyst A 500-mL flask previously purged with nitrogen was placed at 600 ° C.
952 grade silica (specific surface area: 300 m ² / g, pore volume: 1.6 cm ³ /
g, average particle size 80 μm), 20.0 g, and 200 ml of n-hexane were further added to form a slurry. S
Chromium (III) 2-ethylhexanoate manufactured by TREM
7.7 ml of a 1 mol / liter-hexane solution (chromium atom carrying amount: 0.20 wt%) was added, and the mixture was stirred at 30 ° C. for 2 hours. At the end of this time, 38.5 ml of a 1.0 mol / l-toluene solution of methylalumoxane manufactured by Tosoh Akzo was added, and the mixture was stirred at 30 ° C. for 2 hours. At the end of this time, the solvent was removed under vacuum to give a free flowing supported powdered catalyst.

(2) Polymerization and Filtration A 3.0-liter autoclave with a stirrer that has been sufficiently purged with nitrogen in advance (a bottom valve is attached so that liquid can be drawn out from the lower part, and a 400 mesh S
US wire mesh is attached. )), 1.5 liters of isobutane and 100 mg of the catalyst prepared in the above (1) were charged. After the temperature of the autoclave was raised to 85 ° C., hydrogen was supplied at a partial pressure of 0.5 kg / cm ² (the hydrogen concentration in the liquid phase was 0.002 / cm ² ).
8 wt%), and further pressurized with 14 kg / cm ² of ethylene (ethylene concentration in the liquid phase: 8.4 wt%) to start polymerization (hydrogen concentration in the liquid phase (wt%) / ethylene in the liquid phase). Concentration (wt%) = 3.3 × 10 ⁻⁴ ). Ethylene was fed as needed to maintain this ethylene partial pressure. The polymerization temperature is increased by 1 hour for 8 hours by external cooling.
Maintained at 5 ° C. At the end of this time, 1 ml of ethanol was introduced as a deactivator, ethylene feed was stopped, and the polymerization was terminated. After releasing unreacted hydrogen, unreacted ethylene and isobutane from the bottom valve, the contents of the autoclave were taken out. 150 g of white particulate polyethylene were obtained, with an activity of 1500 g polymer / g catalyst / hour. The measurement results of physical properties are shown in Table 1.

(Example 2) In Example 1 (1), 2
-Instead of chromium (III) ethylhexanoate, 7.7 ml of a 0.1 mol / L toluene solution of chromium acetylacetonate manufactured by Wako Pure Chemical Industries, Ltd.
The catalyst was prepared in the same manner as in Example 1 except that 0 wt%) was added, and polymerization and filtration were performed. As a result, 17
0 g of polyethylene was obtained. The activity was 1700 g polymer / g catalyst / hour. The measurement results of physical properties are shown in Table 1.

Example 3 (1) Synthesis of bis (triphenylsilyl) chromate According to the method described in US Pat. No. 2,863,891, chromium trioxide and triphenylsilanol were reacted to form bis (triphenylsilanol). Phenylsilyl) chromate was synthesized. (2) Preparation of catalyst, polymerization, filtration In Example 1 (1), chromium 2-ethylhexanoate was used.
Instead of (III), 488 mg of bis (triphenylsilyl) chromate synthesized in (1) above (chromium atom carrying amount: 0.20 wt%) was added, and the added amount of methylalumoxane manufactured by Tosoh Akzo was 5.0 ml. And Example 1
After stirring at 30 ° C for 2 hours as described in (1),
1.0m of Akzo's diethylaluminum ethoxide
ol / liter-hexane solution (5.0 ml),
After stirring at 2 ° C. for 2 hours, a catalyst was prepared in the same manner as in Example 1, and polymerization and filtration were performed. As a result, 290 g of polyethylene was obtained. The activity was 2900 g polymer / g catalyst / hour. The measurement results of physical properties are shown in Table 1.

Example 4 (1) Gas phase polymerization Eur. Polym. J. , Vol. 21,245 (1
985), a vertical vibration type reactor (capacity: 150 cm ³ , diameter: 5) similar to the fluidized bed reactor described in US Pat.
0 mm, vibration speed 420 times / min (7 Hz), vibration distance 6
cm), and gas phase polymerization was performed. In a reactor previously dried, 100 mg of the catalyst of Example 3 sealed in an ampoule under nitrogen was heated, heated to 90 ° C., and 0.3 kg / cm ^{2 of} hydrogen was introduced at a partial pressure, followed by 14 kg / cm ^2. The polymerization was started by pressurizing with ethylene and starting vibration and breaking the ampule (hydrogen partial pressure / ethylene partial pressure =
2.1 × 10 ^-2 ). In order to maintain the pressure of ethylene in the reactor, ethylene was supplied as needed via a flexible joint. After the polymerization reaction was carried out at 90 ° C. for 2 hours, feeding of ethylene was stopped, the reactor was cooled to room temperature, degassed, and the contents were taken out. As a result, 55
g of polyethylene were obtained. Activity is 280g polymer / g
Catalyst / hour. (2) Washing and Filtration 50 g of the polymer powder obtained in the above (1) was placed in a 2 liter beaker, and 1 liter of hexane was added. The mixture was stirred at 30 ° C. for 2 hours with a magnetic stirrer.
This slurry was filtered, and the obtained polymer was dried under reduced pressure. The measurement results of physical properties are shown in Table 1.

Comparative Example 1 In the polymerization of Example 1, the polymerization was terminated by releasing ethylene, hydrogen and isobutane out of the system at the end of the polymerization time. The contents were taken out, and 150 g of polyethylene was obtained. Activity is 1500
g polymer / g catalyst / hour. The measurement results of physical properties are shown in Table 1. The impact resistance was lower than in the case of Example 1, and the amount of cyclohexane extracted was large.

Comparative Example 2 In the polymerization of Example 2, the polymerization was terminated by releasing ethylene, hydrogen and isobutane out of the system at the end of the polymerization time. The contents were taken out to obtain 170 g of polyethylene. Activity is 1700
g polymer / g catalyst / hour. The measurement results of physical properties are shown in Table 1. The impact resistance was lower than in the case of Example 2, and the amount of cyclohexane extracted was large.

Comparative Example 3 In the polymerization of Example 3, the polymerization was terminated by releasing ethylene, hydrogen and isobutane out of the system at the end of the polymerization time. The contents were taken out to obtain 290 g of polyethylene. Activity is 2900
g polymer / g catalyst / hour. The measurement results of physical properties are shown in Table 1. The impact resistance was lower than in the case of Example 2, and the amount of cyclohexane extracted was large.

(Comparative Example 4) Table 1 shows the measurement results of the physical properties of the polyethylene which was not washed and filtered in Example 4. The impact resistance was lower than in the case of Example 5, and the amount of cyclohexane extracted was large.

[0053]

[Table 1]

[0054]

The ethylene polymer produced by the method of the present invention not only has a sufficiently high resistance to environmental stress cracking (ESCR) and drawdown, but also has a higher resistance than conventional ethylene polymers. It has excellent impact resistance at room temperature and low temperature, and high efficiency of ethylene-based polymer, especially for large-size blow molding, such as high-quality blow molding with very low molecular weight components, which has a very low molecular weight component that deteriorates the working environment due to fuming in the molding process. It provides a polymer that can be produced well and has excellent physical properties and processability, and is industrially valuable. The ethylene polymer obtained in the present invention is suitable for blow molding and the like, particularly for large blow molding.

[Brief description of the drawings]

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

Claims (6)

[Claims] An HLMFR = 0.1 using a catalyst comprising a chromium compound having an organic group, a carrier and an activator.
-20 g / 10 min, density = 0.930-0.980 g /
A method for producing an ethylene-based polymer, characterized in that, when producing an ethylene-based polymer of cm ³ , the produced polymer is washed with a solvent and then separated by filtration or centrifugation. 2. The method for producing an ethylene-based polymer according to claim 1, wherein a catalyst which has been treated with an activating agent after a chromium compound having an organic group is supported on a carrier. 3. The method for producing an ethylene-based polymer according to claim 1, wherein the chromium compound having an organic group is selected from chromium carboxylate, chromium-1,3-diketo compound, chromate ester, and chromamide compound. . 4. The method according to claim 1, wherein the carrier is an inorganic metal oxide and / or an inorganic halide. 5. The inorganic metal oxide carrier has a specific surface area of 50.
１０００1000 m ² / g, pore volume of 0.5-3.0 cm ³
The ethylene according to claim 4, wherein the catalyst has an average particle size of 10 to 200 µm and a chromium compound having an organic group supported thereon as a chromium atom in an amount of 0.05 to 5.0 wt% based on the weight of the carrier. A method for producing a polymer. 6. The method for producing an ethylene-based polymer according to claim 1, wherein the activator is selected from an organic lithium compound, an organic magnesium compound, an organic aluminum compound, and an organic boron compound.