Process for producing a catalyst for ethylene polymerization, and process for producing an ethylene polymer or a copolymer of ethylene and an α-olefin containing the catalyst for ethylene polymerization.

Abstract

To provide an ethylene polymerization catalyst capable of manufacturing a polymer suppressed in density decrease and capable of manufacturing polyethylene efficiently because of short induction time, by reducing a byproduct branch amount contained in an ethylene polymer obtained from a chromium catalyst in which an alumoxane-based compound is used.SOLUTION: A method for producing an ethylene polymerization catalyst having the following steps (a) to (c). Step (a): A chromium compound (b) is supported on an inorganic oxide carrier (a) and activated by firing in a non-reducing atmosphere to obtain a chromium catalyst (A). Step (b): One or more alumoxane-based compounds (c) containing trialkylaluminum and an inorganic solid component (d) having a hydroxyl group or a specific organic compound (e) are mixed to form an alumoxane-based compound-modified composition (B). Step (c): The chromium catalyst (A) and the alumoxane-based compound-modified composition (B) are mixed in an inert hydrocarbon solvent to obtain an ethylene polymerization catalyst.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a method for producing a catalyst for ethylene polymerization.

Background Art

[0002] Hollow plastic molded articles used for storage or transportation of liquid substances are widely used in daily life and industrial fields. Particularly in automotive parts, hollow plastic molded articles used as fuel tanks are replacing conventional fuel tanks made of metal materials. Furthermore, currently, plastic is the most widely used material for manufacturing transport containers such as fuel cans and plastic bottles for flammable liquids, harmful substances, etc. Plastic containers and tanks have the characteristics of being lightweight because of their low weight / volume ratio compared to those made of metal materials, being less likely to corrode such as rust, and having good impact resistance, and are gaining an increasingly wide range of applications.

[0003] Hollow plastic molded articles are often obtained mainly by blow molding from high-density polyethylene (HDPE). Also, in plastic automotive fuel tanks obtained from polyethylene, attention needs to be paid to particularly problematic requirements. Since plastic fuel tanks are classified as important safety components for ensuring the safety of automobiles, particularly high levels are required regarding mechanical strength, durability, and impact resistance, and material development for improving these to sufficiently high levels is desired.

[0004] Conventionally, ethylene polymers polymerized using a chromium compound-supported catalyst have been generally used as ethylene polymers suitable for hollow molding because of their relatively wide molecular weight distribution. The ethylene polymer itself produced using a chromium compound-supported catalyst has been improved in terms of moldability such as melt tension (MT), swell, and drawdown resistance, and the balance between rigidity and durability. Furthermore, improvement in compatibility with the ethylene polymer to be combined and moldability and physical property balance as a composition have been attempted.

[0005] As a method for controlling the physical properties of an ethylene polymer, for example, Patent Document 1 and Patent Document 2 disclose that an ethylene polymer having a wide molecular weight distribution can be obtained by adding an organoaluminum compound to a chromium catalyst supported on a silica carrier, and the moldability is improved. Further, Patent Document 3 and Patent Document 4 disclose that an ethylene polymer excellent in the balance between rigidity and durability can be obtained by a catalyst composed of a chromium compound, an organomagnesium compound or an alumoxane compound and an organoaluminum compound, or a specific organoaluminum compound.

[0006] In the case of a chromium-based catalyst supporting an alumoxane compound, a chromium catalyst showing high activity can be produced, and a high-density ethylene polymer excellent in rigidity can be provided. However, with an increase in the treatment amount of the alumoxane compound, there is a drawback that the amount of by-product branches of the ethylene polymer increases and the density of the ethylene polymer decreases (Patent Document 3).

[0007] Patent Document 5 discloses that a polyethylene composition using an ethylene polymer obtained in the presence of a catalyst for ethylene polymerization, which is produced by sequentially or simultaneously bringing a chromium catalyst supported on an inorganic oxide carrier having a specific structure into contact with an alumoxane compound and a specific organoaluminum compound, exhibits high melt tension. However, further improvement in catalyst performance is desired.

Prior Art Documents

Patent Documents

[0008]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Summary of the Invention

Problems to be Solved by the Invention

[0009] In view of the problems of conventional catalysts for ethylene polymerization, the object of the present invention is to provide a chromium catalyst using an aluminoxane compound, which can produce a polymer with suppressed density reduction by reducing the amount of by-product branches contained in the polymer, and can perform polymerization with good production efficiency with a shortened induction time during polymerization. The object is to provide a method for producing a catalyst for ethylene polymerization.

Means for Solving the Problems

[0010] As a result of intensive studies to achieve the above problems, the present inventors have found that by using a catalyst for ethylene polymerization in which an aluminoxane compound-modified composition obtained by mixing a specific inorganic solid component or organic compound with a chromium catalyst is combined, an ethylene polymer obtained even when using an aluminoxane compound can maintain a low amount of branches, thereby suppressing a decrease in density, and polymerization with good production efficiency with a shortened induction time proceeds. Based on these findings, the present invention has been completed.

[0011] That is, according to a first invention of the present invention, there is provided a method for producing a catalyst for ethylene polymerization, which is characterized by having the following steps (a) to (c). A method for producing a catalyst for ethylene polymerization, which is characterized by having the following steps (a) to (c). Step (a): A step of supporting a chromium compound (b) on an inorganic oxide carrier (a) and subjecting it to calcination activation in a non-reducing atmosphere to obtain a chromium catalyst (A). Step (b): A step of mixing one or more aluminoxane compounds (c) containing trialkylaluminum with an inorganic solid component (d) having a hydroxyl group or at least one organic compound (e) represented by the following general formula (I), general formula (II) or general formula (III) to obtain an aluminoxane compound-modified composition (B). Step (C): A step of mixing the chromium catalyst (A) and the alkoxane compound-modified composition (B) in an inactive hydrocarbon solvent.

[0012]

Chemical formula

[0013]

Chemical formula

[0014] [Chemical formula] [In formula (III), R 5 , R 6 , and R 7 each independently represents a hydrogen atom or a hydrocarbon group having 1 to 30 carbon atoms, and the hydrocarbon group may have a substituent containing a heteroatom selected from an oxygen atom, a sulfur atom, a nitrogen atom, a phosphorus atom, a silicon atom, a halogen atom, an aluminum atom, or a boron atom. Further, R 5 , R 6 , and R 7 may crosslink at any position with each other to form a cyclic structure. X 3 represents an atom selected from an oxygen atom, a sulfur atom, and a nitrogen atom. o represents the valence of X 3 .]

[0015] According to a second invention of the present invention, there is provided a method for producing a catalyst for ethylene polymerization according to the first invention, characterized in that the amount of the inorganic solid component (d) used in the step (b) is 0.01 to 0.5 as the molar ratio ([OH] / [Al]) of the hydroxyl group contained in the inorganic solid component (d) to the aluminum atom contained in the aluminate compound (c). According to a third invention of the present invention, there is provided a method for producing a catalyst for ethylene polymerization according to the first or second invention, characterized in that the amount of the organic compound (e) used in the step (b) is 0.01 to 0.5 as the molar ratio to the aluminum atom contained in the aluminate compound (c).

[0016] According to a fourth invention of the present invention, there is provided a method for producing a catalyst for ethylene polymerization according to any one of the first to third inventions, characterized in that the hydrocarbon group in the general formula (I) has an aryl group. According to the fifth invention of the present invention, there is provided a method for producing a catalyst for ethylene polymerization according to any one of the first to fourth inventions, characterized in that the alumo-xane compound (c) has a methylaluminum structure and an alkylaluminum structure other than the methylaluminum structure.

[0017] According to the sixth invention of the present invention, there is provided a method for producing a catalyst for ethylene polymerization according to the fifth invention, characterized in that the alkylaluminum structure is an isobutylaluminum structure. According to the seventh invention of the present invention, there is provided a catalyst for ethylene polymerization, characterized in that it is obtained from the method for producing a catalyst for ethylene polymerization according to any one of the first to sixth inventions.

[0018] According to the eighth invention of the present invention, there is provided an ethylene polymer or a copolymer of ethylene and an α-olefin, characterized in that it is obtained by using the catalyst for ethylene polymerization according to the seventh invention. According to the ninth invention of the present invention, there is provided a method for producing an ethylene polymer or a copolymer of ethylene and an α-olefin, characterized in that it includes the method for producing a catalyst for ethylene polymerization according to any one of the first to sixth inventions.

Advantages of the Invention

[0019] The catalyst for ethylene polymerization produced by the production method of the present invention has a short induction time during polymerization, so the production efficiency is good, and it is possible to stably produce a catalyst for ethylene polymerization that can efficiently produce high-density polyethylene particularly suitable for hollow plastic molded products. In addition, the ethylene polymer or the copolymer of ethylene and an α-olefin polymerized in the presence of the catalyst for ethylene polymerization produced by the production method of the present invention has substantially the same density as the case where no alumo-xane compound is used, so it is considered to be excellent in the balance of moldability, rigidity (density) and durability.

Embodiments for Carrying Out the Invention

[0020] Hereinafter, the present invention will be described item by item. In this specification, unless otherwise specified, a description using "~" for a numerical range shall include the lower limit value and the upper limit value. For example, in the description "10~20", both the lower limit value "10" and the upper limit value "20" are included. That is, "10~20" has the same meaning as "10 or more and 20 or less".

[0021] [I] Each Component of the Catalyst for Ethylene Polymerization 1. Inorganic Oxide Carrier (a) As the inorganic oxide carrier (a) according to the present invention, oxides of metals in Groups 2, 4, 13 or 14 of the periodic table can be used. Specifically, titania, zirconia, alumina, silica, magnesia, thoria, silica - titania, silica - zirconia, silica - alumina, silica - magnesia or mixtures thereof can be mentioned. Among them, silica is preferably used. Examples of the production method, physical properties and characteristics of the carrier suitable for the inorganic oxide according to the present invention are described in the following documents. (i) C.E. Marsden, Preparation of Catalysts, Volume V, page 215, 1991, Elsevier Science Publishers (ii) C.E. Marsden, Plastics, Rubber and Composites Processing and Applications, Volume 21, page 193, 1994

[0022] As the inorganic oxide carrier (a) according to the present invention, the specific surface area is preferably 100 m 2 / g to 900 m 2 / g. More preferably, it is 100 m 2 / g to 850 m 2 / g, and even more preferably, it is selected to be 150 m 2 / g to 850 m 2 / g. It is preferable to select the specific surface area to be 100 m 2 / g to 900 m 2When it is in the range of / g, the durability and impact resistance of the obtained polyethylene composition will be well balanced.

[0023] As the pore volume of the inorganic oxide carrier (a) according to the present invention, similar to the case of the inorganic oxide carrier used for general chromium catalysts, it is preferably 0.5 cm 3 / g to 5.0 cm 3 / g, more preferably 1.0 cm 3 / g to 3.0 cm 3 / g, still more preferably 1.2 cm 3 / g to 2.5 cm 3 / g is used. When the pore volume is in the range of 0.5 cm 3 / g to 5.0 cm 3 / g, the polymerization activity is good and the production of the inorganic oxide carrier becomes easy. In addition, as the average particle size of the inorganic oxide carrier (a) according to the present invention, those in the range of preferably 10 μm to 200 μm, more preferably 20 μm to 150 μm, and still more preferably 30 μm to 100 μm are used.

[0024] 2. Chromium compound (b) As the chromium compound (b) according to the present invention, a compound in which at least a part of chromium atoms becomes hexavalent by firing and activating in a non-reducing atmosphere after being supported on the inorganic oxide carrier (a) is preferable, and examples include chromium oxide, chromium halide, chromium oxyhalide, chromate, dichromate, chromium nitrate, chromium carboxylate, chromium sulfate, chromium-1,3-diketone compound, chromium acid ester, etc.

[0025] Specifically, examples include chromium(III) oxide, chromium(III) chloride, chromyl chloride, potassium chromate, ammonium chromate, potassium dichromate, chromium nitrate, chromium sulfate, chromium acetate, chromium tris(2-ethylhexanoate), chromium acetylacetonate, bis(tert-butyl) chromate, and the like. Among them, chromium(III) oxide, chromium acetate, and chromium acetylacetonate are preferred. Even when a chromium compound having an organic group such as chromium acetate or chromium acetylacetonate is used, the organic group portion burns during the firing activation in the non-reducing atmosphere described later, and finally, similar to the case of using chromium(III) oxide, it reacts with the hydroxyl groups on the surface of the inorganic oxide carrier, and it is known that at least some of the chromium atoms become hexavalent and are immobilized in the structure of chromate esters ((i) V.J. Ruddick et al., J. Phys. Chem., Volume 100, page 11062, 1996, (ii) S.M. Augustine et al., J. Catal., Volume 161, page 641, 1996).

[0026] 3. Chromium Catalyst (A) The chromium catalyst (A) according to the present invention is a catalyst in which the chromium compound (b) is supported on the inorganic oxide carrier (a). The chromium catalyst (A) is preferably a chromium catalyst in which at least some of the chromium atoms are hexavalent, and is generally classified into catalysts called Phillips catalysts. The outline of this catalyst is described in documents such as "Polyethylene Technology Reader" edited by Kazuo Matsuura and Takataka Mikami, page 81, 2001, Industrial Research Institute; M.P. McDaniel, Advances in Catalysis Vol. 33 p. 47 (1985) Academic Press Inc.; M.P. McDaniel, "Handbook of Heterogeneous Catalysis" p. 2400 (1997) VCH; M.B. Welch et al., "Handbook of Polyolefins Synthesis and Properties" p. 21 (1993) Marcel Dekker. The chromium catalyst (A) is generally produced by mixing the inorganic oxide carrier (a) and the chromium compound (b) and firing and activating (activating) them in a non-reducing atmosphere.

[0027] 4. Alumoxane compound (c) One or more alumoxane compounds (c) containing trialkylaluminum according to the present invention have an Al-O-Al bond in the molecule, and the number of such bonds is usually in the range of 1 to 100, preferably 1 to 50. Such alumoxane compounds are usually products obtained by reacting an organoaluminum compound with water. The reaction of organoaluminum with water is usually carried out in an inert hydrocarbon (solvent). As the inert hydrocarbon, aliphatic hydrocarbons, cycloaliphatic hydrocarbons, and aromatic hydrocarbons such as pentane, hexane, heptane, cyclohexane, methylcyclohexane, benzene, toluene, and xylene can be used, but it is preferable to use aliphatic hydrocarbons or aromatic hydrocarbons.

[0028] As the organoaluminum compound used for the preparation of the alumoxane compound (c) according to the present invention, monoalkylaluminum, dialkylaluminum, and trialkylaluminum can all be used, but preferably trialkylaluminum is used. The alkyl group of the trialkylaluminum used in the preparation of the alumoxane compound (c) according to the present invention can be any of a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a tertiary butyl group, a pentyl group, a hexyl group, an octyl group, a decyl group, a dodecyl group, etc. The above-mentioned organoaluminum compounds can also be used as a mixture of two or more. Those prepared from trimethylaluminum and a trialkylaluminum other than trimethylaluminum are also called modified methylalumoxane (MMAO). The usage ratio of trimethylaluminum and a trialkylaluminum other than trimethylaluminum can be appropriately selected. Preferably, the molar ratio of the trialkylaluminum other than trimethylaluminum / trimethylaluminum is 1 / 9 to 9 / 1. As the alumoxane compound (c) according to the present invention, a modified methylalumoxane prepared from trimethylaluminum and a trialkylaluminum other than trimethylaluminum is preferable from the viewpoint of high activation, and a modified methylalumoxane prepared from trimethylaluminum and triisobutylaluminum is more preferable.

[0029] The alumoxane compound (c) according to the present invention contains trialkylaluminum. The trialkylaluminum contained may be the trialkylaluminum used in the preparation of the alumoxane compound (c), that is, an unreacted raw material, or may be added to the alumoxane compound later. Specific examples of the trialkylaluminum include trialkylaluminums in which the alkyl group is a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a tertiary butyl group, a pentyl group, a hexyl group, an octyl group, a decyl group, a dodecyl group, etc. These may be of one kind or a plurality of kinds.

[0030] When preparing the alumooxane compound (c) according to the present invention, the reaction ratio of water to the organoaluminum compound (water / Al molar ratio) is preferably 0.25 / 1 to 1.2 / 1, particularly preferably 0.5 / 1 to 1 / 1. The reaction temperature is preferably in the range of -70°C to 100°C, more preferably -20°C to 20°C. The reaction time is preferably selected in the range of 5 minutes to 24 hours, more preferably 10 minutes to 5 hours. As the water required for the reaction, not only pure water but also crystal water contained in copper sulfate hydrate, aluminum sulfate hydrate, etc. and components capable of generating water in the reaction system can be used.

[0031] 5. Inorganic solid component (d) having a hydroxyl group The inorganic solid component (d) having a hydroxyl group according to the present invention may be any inorganic solid having a hydroxyl group, and among them, inorganic oxides, clays and clay minerals are exemplified. These plural components may be mixed and used. Examples of the inorganic oxide include silica, alumina, magnesia, zirconia, titania, thoria, and silica-titania, silica-zirconia, silica-alumina, silica-magnesia. Examples of the clay or clay mineral include the following clays or clay minerals described in "Clay Mineralogy" by Haruo Shirakawa, Asakura Shoten (1995). Specifically, smectite group such as montmorillonite, sauconite, beidellite, nontronite, saponite, hectorite, stevensite, vermiculite group such as vermiculite, mica group such as mica, illite, sericite, glauconite, attapulgite, sepiolite, paragonite, bentonite, pyrophyllite, talc, chlorite group, etc. can be mentioned. Among these, inorganic oxides are preferred.

[0032] The inorganic solid component (d) having a hydroxyl group according to the present invention preferably has an average particle size of 10 μm to 200 μm, more preferably 20 μm to 150 μm, and even more preferably 30 μm to 100 μm. When the average particle size is within the above range, it is easy to perform decantation which may be carried out after mixing these inorganic solid components (d) and the alumooxane compound (c). The specific surface area is preferably 100 m 2 / g to 900 m 2 / g, more preferably 100 m 2 / g to 850 m 2 / g is used. The inorganic solid component (d) having a hydroxyl group according to the present invention is preferably dried by heating so that moisture is sufficiently removed. The heating temperature is preferably carried out at 100°C to 1500°C, more preferably 200°C to 800°C. The heating time is not particularly limited, but is preferably 1 hour to 100 hours, more preferably 3 hours to 30 hours. The amount of hydroxyl groups contained in the inorganic solid component (d) after the heat treatment is preferably 0.1 mmol-OH / g to 10 mmol-OH / g, more preferably 0.5 mmol-OH / g to 5.0 mmol-OH / g, and even more preferably 1.0 mmol-OH / g to 3.0 mmol-OH / g.

[0033] 6. Organic compound (e) Examples of the organic compound (e) according to the present invention include compounds represented by the following general formulas (I), (II) or (III). These are compounds having an active hydrogen or a coordinating compound.

[0034] [Chemical formula] [In formula (I), X 1 represents an atom selected from an oxygen atom, a sulfur atom, a nitrogen atom, and a phosphorus atom. R 1 represents a hydrocarbon group having 1 to 30 carbon atoms, and the hydrocarbon group may have a substituent containing a hetero atom selected from an oxygen atom, a sulfur atom, a nitrogen atom, a phosphorus atom, a silicon atom, a halogen atom, an aluminum atom, or a boron atom. When there are a plurality of R 1 , each R 1 may be the same or different, and may crosslink at any position to form a cyclic structure. m represents the valence of X 1 . n represents an integer from 0 to less than m.

[0035] R 1 Examples of the hydrocarbon group having 1 to 30 carbon atoms represented by 1 include an alkyl group, a cycloalkyl group, an alkenyl group, an aryl group, and an arylalkyl group. Among these, the preferred hydrocarbon group having 1 to 30 carbon atoms is an alkyl group, a cycloalkyl group, an aryl group, or an arylalkyl group, more preferably an alkyl group or an aryl group, and still more preferably an aryl group. Examples of the alkyl group include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, a tert-butyl group, an n-pentyl group, a neopentyl group, an isopentyl group, an n-hexyl group, an n-heptyl group, an n-octyl group, an n-decyl group, an n-nonyl group, an n-decyl group, an n-dodecyl group, an n-tridecyl group, an n-tetradecyl group, an n-pentadecyl group, an n-hexadecyl group, an n-heptadecyl group, an n-octadecyl group, an n-nonadecyl group, an n-eicosyl group, an n-pentacosyl group, and an n-triacontyl group. The preferred alkyl group has 1 to 10 carbon atoms, and more preferably 1 to 6 carbon atoms. Examples of the cycloalkyl group include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a norbornyl group, and an adamantyl group. Examples of the alkenyl group include a vinyl group, a propenyl group, and a cyclohexenyl group. Examples of the aryl group include a phenyl group, a tolyl group, a xylyl group, a trimethylphenyl group, a tetramethylphenyl group, a pentamethylphenyl group, an ethylphenyl group, an n-propylphenyl group, an isopropylphenyl group, an n-butylphenyl group, a sec-butylphenyl group, a tert-butylphenyl group, an isobutylphenyl group, an n-pentylphenyl group, a neopentylphenyl group, an n-hexylphenyl group, an n-octylphenyl group, an n-decylphenyl group, an n-dodecylphenyl group, an n-tetradecylphenyl group, a naphthyl group, a biphenyl group, an anthracenyl group, and a phenanthryl group. The preferred aryl group has 6 to 20 carbon atoms, and more preferably 6 to 15 carbon atoms. Examples of the arylalkyl group include a benzyl group, a phenylethyl group, and a phenylpropyl group.

[0036] R 1 Examples of the substituent containing a hetero atom selected from an oxygen atom, a sulfur atom, a nitrogen atom, a phosphorus atom, a silicon atom, a halogen atom, an aluminum atom, or a boron atom, which may be possessed by a hydrocarbon group having 1 to 30 carbon atoms represented by include an alkoxy group, a carbonyl group, a cyano group, an isocyanato group, a nitro group, a nitroso group, an azo group, a disulfide group, a sulfino group, a sulfonic acid group, an isothiocyanato group, a chloro group, a bromo group, an iodo group, an iodoxysilane group, an iodyl group, a fluoro group, a trifluoromethyl group, a phosphoric acid group, a phosphonic acid group, a phosphate ester group, a silyl group, a boronic acid, a boryl group, and the like. Among these, an alkoxy group, a cyano group, a nitro group, a sulfonic acid group, a chloro group, a bromo group, an iodo group, a fluoro group, a trifluoromethyl group, a phosphoric acid group, a phosphonic acid group, and a phosphate ester group are preferable, an alkoxy group, a nitro group, a sulfonic acid group, a chloro group, a bromo group, an iodo group, a fluoro group, a phosphoric acid group, a phosphonic acid group, and a phosphate ester group are more preferable, and a chloro group, a bromo group, an iodo group, and a fluoro group are even more preferable.

[0037] R 1 Examples of the structure in the case where the hydrocarbon group having 1 to 30 carbon atoms represented by may be crosslinked at an arbitrary position to form a cyclic structure include cyclopropane, cyclobutane, cyclopentane, cyclohexane, norbornane, adamantane, pentalene, indene, naphthalene, azulene, heptalene, biphenylene, fluorene, anthracene, pyrene, tetracene, pentacene, coronene, bicyclopropane, and the like.

[0038] Examples of the organic compound represented by the general formula (I) according to the present invention include alcohol compounds, phenol compounds, ether compounds, carboxylic acid compounds, ester compounds, thiol compounds, thiophenol compounds, thioether compounds, thiocarboxylic acid compounds, thioester compounds, primary amine compounds, secondary amine compounds, tertiary amine compounds, primary phosphine compounds, secondary phosphine compounds, tertiary phosphine compounds, and the like. Preferably, they are alcohol compounds, phenol compounds, carboxylic acid compounds, thiol compounds, thiophenol compounds, primary amine compounds, secondary amine compounds, primary phosphine compounds, and secondary phosphine compounds. More preferably, they are alcohol compounds and phenol compounds. Even more preferably, they are phenol compounds. Specific examples of the alcohol compound include methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, sec-butyl alcohol, tert-butyl alcohol, n-pentanol, neopentanol, isopentanol, n-hexanol, n-heptanol, n-octanol, n-decanol, cyclohexanol, benzyl alcohol, 4-fluoro-1-butanol, 4,4-difluoro-1-butanol, 4,4,4-trifluoro-1-butanol, 4-chloro-1-butanol, 4-bromo-1-butanol, 4-iodo-1-butanol, ethylene glycol, propylene glycol, and the like. Preferably, they are methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, sec-butyl alcohol, tert-butyl alcohol, n-pentanol, neopentanol, isopentanol, n-hexanol, n-heptanol, n-octanol, n-decanol, cyclohexanol, benzyl alcohol. More preferably, they are ethanol, n-propanol, isopropanol, n-butanol, isobutanol, sec-butyl alcohol, tert-butyl alcohol, n-pentanol, neopentanol, isopentanol, n-hexanol.

[0039] Specific examples of the thiol compound include compounds in which the oxygen atom of the above alcohol compound is changed to a sulfur atom. Methanethiol, ethanethiol, n-propanethiol, isopropanethiol, n-butanethiol, isobutanethiol, sec-butanethiol, tert-butanethiol, n-pentanethiol, neopentanethiol, isopentanethiol, n-hexanethiol, n-heptanethiol, n-octanethiol, n-decanethiol, cyclohexanethiol, benzylthiol, 4-fluoro-1-butanethiol, 4,4-difluoro-1-butanethiol, 4,4,4-trifluoro-1-butanethiol, 4-chloro-1-butanethiol, 4-bromo-1-butanethiol, 4-iodo-1-butanethiol, ethanedithiol, propanedithiol, etc. are included. Preferably, methanethiol, ethanethiol, n-propanethiol, isopropanethiol, n-butanethiol, isobutanethiol, sec-butanethiol, tert-butanethiol, n-pentanethiol, neopentanethiol, isopentanethiol, n-hexanethiol, n-heptanol, n-octanol, n-decanethiol, cyclohexanethiol, benzylthiol, and more preferably, ethanethiol, n-propanethiol, isopropanethiol, n-butanethiol, isobutanethiol, sec-butanethiol, tert-butanethiol, n-pentanethiol, neopentanethiol, isopentanethiol, n-hexanethiol.

[0040] Specific examples of the phenol compound include phenol, methylphenol, dimethylphenol, trimethylphenol, tetramethylphenol, pentamethylphenol, ethylphenol, n-propylphenol, isopropylphenol, n-butylphenol, sec-butylphenol, tert-butylphenol, isobutylphenol, n-pentylphenol, neopentylphenol, n-hexylphenol, n-octylphenol, n-decylphenol, n-dodecylphenol, n-tetradecylphenol, 2-methylphenol, 3-methylphenol, 2,3-dimethylphenol, 2,4-dimethylphenol, 2,5-dimethylphenol, 2,6-dimethylphenol, 2,4,6-trimethylphenol, 2,6-di(tert-butyl)phenol, 2,6-di(tert-butyl)-4-methylphenol, 2-chlorophenol, 3-chlorophenol, 2,3-dichlorophenol, 2,4-dichlorophenol, 2,5-dichlorophenol, 2,6-dichlorophenol, 2,4,6-trichlorophenol, 2-fluorophenol, 2-bromophenol, 2-iodophenol, and the like. Preferably, they are phenol, 2-methylphenol, 2,6-dimethylphenol, 2,4,6-trimethylphenol, 2,6-di(tert-butyl)phenol, 2,6-di(tert-butyl)-4-methylphenol.

[0041] Specific examples of the thiophenol compound include compounds in which the oxygen atom of the above phenol compound is changed to a sulfur atom. These thiophenol compounds are compounds represented by adding thio as a prefix to the above phenol compound. Specific examples of the ether compound include methyl ether, ethyl methyl ether, ethyl ether, n-propyl ether, n-butyl ether, n-pentyl ether, n-hexyl ether, n-heptyl ether, n-pentyl ether, n-octyl ether, n-decyl ether, cyclohexyl ether, phenyl ether, benzyl ether, tetrahydrofuran, furan, benzofuran, dibenzofuran, pyran, benzopyran, dibenzopyran, spiropyran, and the like. Specific examples of the thioether compound include compounds in which the oxygen atom of the above ether compound is changed to a sulfur atom. Specifically, methyl thioether, ethyl methyl thioether, ethyl thioether, n-propyl thioether, n-butyl thioether, n-pentyl thioether, n-hexyl thioether, n-heptyl thioether, n-pentyl thioether, n-octyl thioether, n-decyl thioether, cyclohexyl thioether, phenyl thioether, benzyl thioether, and the like can be mentioned. In addition to these thioether compounds, tetrahydrothiophene, thiophene, benzothiophene, dibenzothiophene, thiopyran, thianthrene, and the like can be mentioned.

[0042] Specific examples of the carboxylic acid compound include methanoic acid, ethanoic acid, propanoic acid, butanoic acid, pentanoic acid, hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, dodecanoic acid, tetradecanoic acid, hexadecanoic acid, heptadecanoic acid, octadecanoic acid, oleic acid, linoleic acid, linolenic acid, arachidonic acid, eicosapentaenoic acid, docosahexaenoic acid, sorbic acid, lactic acid, malic acid, citric acid, benzoic acid, phthalic acid, isophthalic acid, terephthalic acid, salicylic acid, gallic acid, mellitic acid, cinnamic acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, fumaric acid, maleic acid, aconitic acid, pyruvic acid, oxaloacetic acid, and the like. Specific examples of the thiocarboxylic acid compound include compounds in which the oxygen atom of the above carboxylic acid is changed to a sulfur atom. These thiocarboxylic acid compounds are compounds represented by adding thio as a prefix to the above carboxylic acid.

[0043] Specific examples of the ester compound include compounds in which the hydrogen atom of the carboxy group of the above carboxylic acid compound is changed to an alkyl group or an aryl group. These ester compounds are compounds represented by adding an alkyl group or an aryl group as a suffix to the above carboxylic acid compound. Specifically, methyl methanoate, ethyl methanoate, phenyl methanoate, methyl ethanoate, ethyl ethanoate, phenyl ethanoate, methyl propanoate, methyl butanoate, methyl pentanoate, methyl hexanoate, methyl heptanoate, methyl octanoate, methyl nonanoate, methyl decanoate, methyl dodecanoate, methyl tetradecanoate, methyl hexadecanoate, methyl heptadecanoate, methyl octadecanoate, methyl oleate, methyl linoleate, methyl linolenate, methyl arachidonate, methyl eicosapentaenoate, methyl docosahexaenoate, methyl sorbate, methyl lactate, methyl malate, methyl citrate, methyl benzoate, methyl phthalate, methyl isophthalate, methyl terephthalate, methyl salicylate, methyl gallate, methyl mellitate, methyl cinnamate, methyl oxalate, methyl malonate, methyl succinate, methyl glutarate, methyl adipate, methyl fumarate, methyl maleate, methyl aconitate, methyl pyruvate, methyl oxaloacetate, and the like can be mentioned. Specific examples of the thioester compound include compounds in which the oxygen atom of the above ester compound is changed to a sulfur atom. These thioester compounds are compounds represented by adding thio as a prefix to the above ester.

[0044] Specific examples of the amine compound include methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, n-propylamine, isopropylamine, n-butylamine, sec-butylamine, tert-butylamine, isobutylamine, n-pentylamine, neopentylamine, isopentylamine, n-hexylamine, n-heptylamine, n-octylamine, n-decylamine, cyclohexylamine, dicyclohexylamine, tricyclohexylamine, phenylamine, diphenylamine, triphenylamine, benzylamine, pyrrole, 1-pyrroline, 2-pyrroline, 3-pyrroline, pyrrolidine, oxazole, isoxazole, imidazoline, pyrazolidine, pyridine, piperidine, pyridazine, pyrimidine, pyrazine, piperazine, morpholine, indole, indoline, indazole, quinoline, isoquinoline, cinnoline, phthalazine, quinazoline, quinoxaline, naphthyridine, purine, pteridine, indolizine carbazole, acridine, phenazine, phenanthridine, phenanthroline, phenoxazine, quinuclidine, and the like.

[0045] Examples of the phosphine compound include methylphosphine, dimethylphosphine, trimethylphosphine, ethylphosphine, diethylphosphine, triethylphosphine, n-propylphosphine, isopropylphosphine, n-butylphosphine, sec-butylphosphine, tert-butylphosphine, isobutylphosphine, n-pentylphosphine, neopentylphosphine, isopentylphosphine, n-hexylphosphine, n-heptylphosphine, n-octylphosphine, n-decylphosphine, cyclohexylphosphine, dicyclohexylphosphine, tricyclohexylphosphine, phenylphosphine, diphenylphosphine, triphenylphosphine, benzylphosphine, phosphirane, phosphirene, phospholine, phosphorane, phosphole, phospholene, and the like.

[0046]

Chemical formula

[0047] Examples of the hydrocarbon group having 1 to 30 carbon atoms represented by R 2 、R 3 、and R 4 include, for example, an alkyl group, a cycloalkyl group, an alkenyl group, an aryl group, and an arylalkyl group, and preferably include an alkyl group, a cycloalkyl group, an alkenyl group, and an aryl group. Examples of the alkyl group include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, a tert-butyl group, an n-pentyl group, a neopentyl group, an isopentyl group, an n-hexyl group, an n-heptyl group, an n-octyl group, an n-decyl group, an n-nonyl group, an n-decyl group, and the like. Among these, an alkyl group having 1 to 10 carbon atoms is preferable, and an alkyl group having 1 to 6 carbon atoms is more preferable. Examples of the cycloalkyl group include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, and the like. Examples of the alkenyl group include a vinyl group, a propenyl group, and the like. Examples of the aryl group include, for example, a phenyl group and the like. Among these, an aryl group having 6 to 20 carbon atoms is preferable, and an aryl group having 6 to 15 carbon atoms is more preferable.

[0048] R 2 、R 3 and R 4 The substituent containing a hetero atom selected from an oxygen atom, a sulfur atom, a nitrogen atom, a phosphorus atom, a silicon atom, a halogen atom, an aluminum atom or a boron atom, which may be possessed by a hydrocarbon group having 1 to 30 carbon atoms represented by, is R 1 Those exemplified by R

[0049] Examples of the organic compound represented by the general formula (II) according to the present invention include an organic silanol compound, an organic silylthiol compound, an organic silylamine compound, an organic silylphosphine compound, etc., preferably an organic silanol compound and an organic silylthiol compound, and more preferably an organic silanol compound. Specific examples of the organic silanol compound include trimethylsilanol, triethylsilanol, tri(n-propyl)silanol, tri(isopropyl)silanol, tri(n-butyl)silanol, tri(sec-butyl)silanol, tri(tert-butyl)silanol, tri(isobutyl)silanol, tri(n-pentyl)silanol, tri(neopentyl)silanol, tri(isopentyl)silanol, tri(n-hexyl)silanol, tri(n-octyl)silanol, tri(n-decyl)silanol, tri(n-dodecyl)silanol, tri(n-pentadecyl)silanol, tri(cyclohexyl)silanol, triphenylsilanol, ethyldimethylsilanol, isobutyldimethylsilanol, phenyldimethylsilanol, phenylethylmethylsilanol, phenylisobutylmethylsilanol, methyldiphenylsilanol, ethyldiphenylsilanol, isobutyldiphenylsilanol, etc.

[0050] Specific examples of the organic silylthiol compound include compounds in which the oxygen atom of the above organic silanol compound is changed to a sulfur atom. These organic silylthiol compounds are compounds represented by replacing the silanol in the above organic silanol compound with silylthiol. Specific examples of the organic silylamine compound include compounds in which the oxygen atom of the above organic silanol compound is changed to a nitrogen atom. These organic silylamine compounds are compounds represented by replacing the silanol in the above organic silanol compound with silylamine. Specific examples of the organic silylphosphine compound include compounds in which the oxygen atom of the above organic silanol compound is changed to a phosphorus atom. These organic silylphosphine compounds are compounds represented by replacing the silanol in the above organic silanol compound with silylphosphine.

[0051] [Chemical formula] [In formula (III), R 5 , R 6 , and R 7 each independently represent a hydrogen atom or a hydrocarbon group having 1 to 30 carbon atoms, and the hydrocarbon group may have a substituent containing a heteroatom selected from an oxygen atom, a sulfur atom, a nitrogen atom, a phosphorus atom, a silicon atom, a halogen atom, an aluminum atom, or a boron atom. Further, R 5 , R 6 , and R 7 may crosslink at any position with each other to form a cyclic structure. X 3 represents an atom selected from an oxygen atom, a sulfur atom, and a nitrogen atom. o represents the valence of X 3 .]

[0052] Examples of the hydrocarbon group having 1 to 30 carbon atoms represented by R 5 , R 6 , and R 7 include, for example, an alkyl group, a cycloalkyl group, an alkenyl group, an aryl group, and an arylalkyl group. Among these, an alkyl group, a cycloalkyl group, an aryl group, and an arylalkyl group are preferable, an alkyl group, an aryl group are more preferable, and an aryl group is further preferable. Examples of the alkyl group include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, sec-butyl group, tert-butyl group, n-pentyl group, neopentyl group, isopentyl group, n-hexyl group, n-heptyl group, n-octyl group, n-decyl group, n-nonyl group, n-decyl group, n-dodecyl group, n-tridecyl group, n-tetradecyl group, n-pentadecyl group, n-hexadecyl group, n-heptadecyl group, n-octadecyl group, n-nonadecyl group, n-eicosyl group, n-pentacosyl group, n-triacontyl group and the like. Among these, an alkyl group having 1 to 10 carbon atoms is preferable, and an alkyl group having 1 to 6 carbon atoms is more preferable.

[0053] Examples of the cycloalkyl group include cyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group, norbornyl group, adamantyl group and the like. Examples of the alkenyl group include vinyl group, propenyl group and cyclohexenyl group and the like. Examples of the aryl group include, for example, phenyl group, tolyl group, xylyl group, trimethylphenyl group, tetramethylphenyl group, pentamethylphenyl group, ethylphenyl group, n-propylphenyl group, isopropylphenyl group, n-butylphenyl group, sec-butylphenyl group, tert-butylphenyl group, isobutylphenyl group, n-pentylphenyl group, neopentylphenyl group, n-hexylphenyl group, n-octylphenyl group, n-decylphenyl group, n-dodecylphenyl group, n-tetradecylphenyl group, naphthyl group, biphenyl group, anthracenyl group and phenanthryl group and the like. Among these, an aryl group having 6 to 20 carbon atoms is preferable, and an aryl group having 6 to 15 carbon atoms is more preferable. Examples of the arylalkyl group include benzyl group, phenylethyl group and phenylpropyl group and the like.

[0054] R 5 、R 6 and R 7Examples of the substituent containing a heteroatom selected from an oxygen atom, a sulfur atom, a nitrogen atom, a phosphorus atom, a silicon atom, a halogen atom, an aluminum atom or a boron atom, which may be possessed by a hydrocarbon group having 1 to 30 carbon atoms represented by R 1 Those exemplified by 1 are also exemplified here in the same manner.

[0055] Examples of the organic compound represented by the general formula (III) according to the present invention include an aldehyde compound, a ketone compound, a thioaldehyde compound, a thioketone compound, an imine compound and the like. Preferably, they are an aldehyde compound and an imine compound. Specific examples of the aldehyde compound include formaldehyde, acetaldehyde, propanal, butanal, pentanal, hexanal, heptanal, octanal, nonanal, decanal, benzaldehyde, phenylacetaldehyde and the like. Specific examples of the thioaldehyde compound include thioformaldehyde, thioacetamide, propanethial, butanethial, pentanethial, hexanethial, heptanethial, octanethial, nonanethial, decanethial, thiobenzaldehyde, thiophenylacetaldehyde, benzenethioacetaldehyde and the like. Specific examples of the ketone compound include dimethyl ketone, diethyl ketone, methyl ethyl ketone, dipropyl ketone, diisopropyl ketone, dibutyl ketone, di-sec-butyl ketone, di-tert-butyl ketone, pentyl ketone, hexyl ketone, heptyl ketone, dioctyl ketone, didecyl ketone, dinonyl ketone, didecyl ketone, didodecyl ketone, ditridecyl ketone, ditetradecyl ketone, dipentadecyl ketone, dicyclohexyl ketone, cyclohexanone, benzophenone and the like. Specific examples of the thioketone compound include compounds in which the oxygen atom of the above ketone compound is changed to a sulfur atom. These thioketone compounds are compounds represented by replacing the ketone in the above ketone compound with a thioketone. Specific examples of the imine compound include 2-propanimine, methylisopropylideneamine, phenylisopropylideneamine, 2-butanimine, 3-propanimine, 3-pentaimine, cyclopentaneimine, cyclohexaneimine, N-cyclohexylidenemethanamine, N-cyclohexylidenebenzenamine, N-benzylideneamine, N-benzylidenemethanamine, N-benzylidenebenzenamine, and the like.

[0056] 7. Modified composition (B) of alumo-xane compound The alumo-xane compound modified composition (B) according to the present invention can be obtained by mixing the alumo-xane compound (c) with the inorganic solid component (d) having a hydroxyl group or at least one organic compound (e) represented by the general formula (I), general formula (II) or general formula (III). (1) Alumo-xane compound modified composition (B) obtained by mixing the alumo-xane compound (c) and the inorganic solid component (d) having a hydroxyl group The alumo-xane compound (c) according to the present invention contains trialkylaluminum as described in [I] 4. This trialkylaluminum is considered to react with the hydroxyl group of the inorganic solid component (d) and be supported on the inorganic solid component when mixed with the inorganic solid component (d) in a solvent such as an inert hydrocarbon. As an example, Scheme 1 shows the possible reaction when using modified methylaluminoxane (MMAO) prepared using trimethylaluminum and triisobutylaluminum in the alumo-xane compound (c) and silica in the inorganic solid component (d). In [-(Me)Al-O-] shown in Scheme 1 x "-(Me)Al-" represents a methylaluminum structure in which a methyl group (Me) is bonded to an aluminum atom (Al). In the present specification, such a structure in which an alkyl group (R a ) is bonded to an aluminum atom ("-(R a)Define (Al-」) as an alkyl aluminum structure. After the reaction, by separating the solution and the inorganic solid component supported with the trialkyl aluminum component using a decanter or the like, it is considered that a solution of the aluminoxane compound-modified composition (B) from which the trialkyl aluminum has been removed is provided.

[0057] [Chemical formula] <scheme1>

[0058] (2) An alumo-xane compound-modified composition (B) obtained by mixing with at least one organic compound (e) represented by the general formula (I), general formula (II) or general formula (III) The trialkylaluminum contained in the alumo-xane compound is considered to react with the active hydrogen of the organic compound (e) or coordinate with the organic compound (e) in a solvent such as an inactive hydrocarbon solvent, resulting in a decrease in reactivity. Therefore, the trialkylaluminum reaction product that has reacted with the active hydrogen of the organic compound (e) or the trialkylaluminum coordination compound that has coordinated with the organic compound (e) is considered not to affect the formation of polymerization active sites or the polymerization reaction even if it is present in the solution. As an example, Scheme 2 shows the reaction when MMAO is used for the alumo-xane compound and 2,6-di(tert-butyl)-4-methylphenol is used for the organic compound (e).

[0059] [Chemical formula] <scheme2>

[0060] [II] Process for Producing Catalyst for Ethylene Polymerization The process for producing the catalyst for ethylene polymerization of the present invention has the following steps (a) to (c). Step (a): A step of supporting a chromium compound (b) on an inorganic oxide carrier (a), firing and activating it in a non-reducing atmosphere to obtain a chromium catalyst (A). Step (b): A step of mixing one or more alumoxane-based compounds (c) containing trialkylaluminum with an inorganic solid component (d) having a hydroxyl group or at least one organic compound (e) represented by the general formula (I), general formula (II) or general formula (III) to obtain an alumoxane-based compound-modified composition (B). Step (c): A step of mixing the chromium catalyst (A) and the alumoxane-based compound-modified composition (B) in an inert hydrocarbon solvent.

[0061] The function and mechanism of the catalyst for ethylene polymerization according to the present invention are considered as follows. The reaction occurring on the silica surface after supporting the chromium compound on the surface of the inorganic oxide carrier by using silica as the inorganic oxide carrier (a) and chromium acetate as the chromium compound (b) and then firing and activating it is shown in the following Scheme 3. When silica and chromium acetate (aqueous solution) are mixed, the silanol group in the silica reacts with chromium acetate, and chromium acetate is supported on the silica. By firing and activating this, the structure derived from the organic substance (acetic acid structure) is incinerated and removed, and a chromium acid ester structure is formed. Then, when this chromium acid ester form and ethylene are mixed, the chromium acid ester structure is reduced by ethylene, and polymerization active precursor 1 is formed. The time required for this reduction (the time from the chromium acid ester form to the formation of polymerization active precursor 1) is called the induction time. It is considered that the polymerization of ethylene is initiated by becoming polymerization active precursor 1 by a reduction reaction after supporting the chromium compound on the inorganic oxide carrier in this way.

[0062]

Chemical Formula

[0063] Also, it is known that when a chromium catalyst and an aluminoxane compound are mixed, the polymerization activity increases significantly. However, in this method, even if the productivity is improved, the density of the obtained ethylene polymer decreases. This is presumably because trialkylaluminum contained in the aluminoxane compound generates alkenes such as 1 - hexene, which are copolymerized like a comonomer and incorporated into the polymer, resulting in the generation of by - product branches in the polymer. In the present invention, by using an aluminoxane - based compound modified composition (B) in which trialkylaluminum is reduced by an inorganic solid component (d) having a hydroxyl group, or an organic compound (e) having an active hydrogen or a coordination compound that reacts with or coordinates to the organic compound (e) to reduce the reactivity of alkylaluminum, the generation of the polymerization activity precursor 1 is promoted, so the induction time is short, and the amount of by - product branches is reduced, so it is considered that the decrease in the density of the obtained ethylene polymer can be suppressed.

[0064] 1. Step (a) Obtaining a chromium catalyst (A) (1) Supporting a chromium compound (b) on an inorganic oxide carrier (a) The step (a) according to the present invention is a step of supporting a chromium compound (b) on an inorganic oxide carrier (a), firing and activating it in a non - reducing atmosphere to obtain a chromium catalyst (A). The supporting of the chromium compound (b) on the inorganic oxide carrier (a) is preferably carried out in a state where at least a part of the chromium atoms in the chromium compound are in a hexavalent state. If this can be achieved, it is not particularly limited and can be carried out by known methods such as impregnation, solvent evaporation, sublimation, etc., and an appropriate method can be used depending on the type of chromium compound used. The amount of the chromium compound to be supported is preferably 0.2 - 2.0% by weight, more preferably 0.3 - 1.7% by weight, and even more preferably 0.5 - 1.5% by weight based on the carrier as chromium atoms.

[0065] In the present invention, a fluorine compound can also be further contained in a chromium catalyst (A) in which a chromium compound (b) is supported on an inorganic oxide carrier (a). The method of containing the fluorine compound (fluorination) can be carried out by a known method such as a method of impregnating a fluorine compound solution in a solvent and then distilling off the solvent, or a method of sublimating the fluorine compound without using a solvent. An appropriate and suitable method may be used according to the type of chromium compound used. The fluorine compound may be contained after the chromium compound is supported on the inorganic oxide carrier, or the chromium compound may be supported after the fluorine compound is contained. However, it is preferable to contain the fluorine compound after the chromium compound is supported. The content of the fluorine compound, as the content of fluorine atoms, is preferably 0.1 to 10% by weight, more preferably 0.3 to 8% by weight, and still more preferably 0.5 to 5% by weight.

[0066] As the fluorine compound, fluorine-containing salts such as hydrogen fluoride HF, ammonium fluoride NH4F, ammonium hexafluorosilicate (NH4)2SiF6, ammonium hexafluoroborate NH4BF4, ammonium bifluoride (NH4)HF2, ammonium hexafluorophosphate NH4PF6, and tetrafluoroboric acid HBF4 are used. Among them, ammonium hexafluorosilicate and ammonium bifluoride are preferable. From the viewpoint of uniformity, it is preferable to dissolve these in an organic solvent such as water or alcohol and then impregnate the chromium catalyst, but it may also be simply mixed with the chromium catalyst in a solid state. When dissolving and impregnating, it is more preferable to use an organic solvent such as alcohol in order to suppress the shrinkage of the pore volume due to surface tension. When a solvent is used, the solvent is removed and dried by a known method such as air drying, vacuum drying, or spray drying.

[0067] By the firing activation (activation) in a non-reducing atmosphere described below, these fluorine compounds fluorinate the inorganic oxide carrier by thermal decomposition. For example, when silica is used as the inorganic oxide carrier and ammonium fluorosilicate is used as the fluorine compound, ammonium fluorosilicate thermally decomposes as follows to generate hydrogen fluoride HF and silicon tetrafluoride SiF4. (NH4)2SiF6→ 2NH3+ 2HF + SiF4

[0068] Furthermore, it is known that HF and SiF4 react with silanol groups on the silica surface to fluorinate (see B. Rebenstorf; Journal of Molecular Catalysis Vol.66 p.59 (1991), A. Noshay et al. "Transition Metal Catalyzed Polymerizations-Ziegler·Natta and Metathesis Polymerizations" p.396 (1988) Cambridge University Press). Si-OH + HF → Si-F + H2O Si-OH + SiF4→ Si-O-SiF3+ HF 2Si-OH + SiF4→ (Si-O)2SiF2+ 2HF

[0069] Therefore, even when only a solid of a fluorine compound such as a fluorine-containing salt is mixed with the chromium catalyst, eventually the fluorine compound thermally decomposes, so the same reaction occurs and the chromium catalyst is fluorinated. Alternatively, a method of introducing the fluorine compound during the firing activation (activation) step may be used. However, in that case, since the solid of the fluorine compound is fluidized in the gas, it is preferable to use a fluorine compound solid in the form of as fine particles as possible from the viewpoint of uniformity.

[0070] (2) Firing activation in a non-reducing atmosphere After supporting a chromium compound (b) on an inorganic oxide carrier (a), and in some cases, further supporting a fluorine compound, firing activation is performed to obtain a chromium catalyst (A). The firing activation is preferably performed at a temperature of 300°C to 950°C, more preferably 325°C to 800°C, and even more preferably 350°C to 650°C. When the firing activation is performed in the range of 300°C to 950°C, the catalyst is considered to exhibit good performance from the viewpoint of polymerization activity. The firing activation can be performed in a non-reducing atmosphere substantially free of moisture, for example, under oxygen or air. At this time, an inert gas may coexist. Preferably, firing activation is performed in a fluidized state using air that has been sufficiently dried by passing through molecular sieves or the like, so that at least a part of the chromium atoms of the chromium compound supported on the inorganic oxide carrier is oxidized to hexavalent and chemically fixed on the carrier.

[0071] 2. Step (b): Obtaining an aluminoxane-based compound-modified composition (B) (1) Mixing of an aluminoxane-based compound (c) and an inorganic solid component (d) having a hydroxyl group One or more aluminoxane-based compounds (c) containing trialkylaluminum are mixed with an inorganic solid component (d) having a hydroxyl group in an inert hydrocarbon solvent to obtain an aluminoxane-based compound-modified composition (B). Here, it is considered that the reaction described in [I] 7.(1) above occurs.

[0072] When mixing and reacting an alumo-xane compound (c) and an inorganic solid component (d) having a hydroxyl group, the ratio of the amount (moles) of the hydroxyl groups of the inorganic solid component (d) having a hydroxyl group to the amount (moles) of the aluminum atoms present in the alumo-xane compound is preferably 0.01 to 0.5, more preferably 0.03 to 0.3, and even more preferably 0.05 to 0.1, and they are mixed to obtain an alumo-xane compound-modified composition (B). As a method for mixing the alumo-xane compound (c) and the inorganic solid component (d) having a hydroxyl group, there is no particular limitation as long as the two are mixed in an inert hydrocarbon. For example, an inorganic solid component (d) having a hydroxyl group that has been heated and dried is mixed with an inert hydrocarbon solvent such as propane, n-butane, isobutane, n-pentane, isopentane, hexane, heptane, octane, decane, cyclohexane, benzene, toluene, xylene, etc. to form a slurry state, and a solution of the alumo-xane compound (c) is added thereto; a slurry of the inorganic solid component (d) is added to a solution of the alumo-xane compound (c); a method of adding and mixing the inorganic solid component (d) having a hydroxyl group in a solid state to a solution of the alumo-xane compound (c), etc. may be mentioned. Among these, a method in which an inorganic solid component (d) having a hydroxyl group that has been heated and dried is mixed with an inert hydrocarbon solvent to form a slurry state, and a solution of the alumo-xane compound (c) is added thereto is preferable.

[0073] The aluminoxane compound (c) used herein may be diluted with the above-mentioned inert hydrocarbon solvent or added without dilution. The solvent during mixing with the diluting solvent may be the same or different. The amount of the inert hydrocarbon solvent used is preferably an amount that allows stirring at least in a slurry state during the mixing of the aluminoxane compound (c) and the inorganic solid component (d) having a hydroxyl group. With such an amount, the amount of the solvent used is not particularly limited. Also, the temperature during mixing is preferably -20°C to 150°C, more preferably -10°C to 100°C, still more preferably 0°C to 80°C, and the time is preferably 5 minutes to 12 hours, more preferably 30 minutes to 10 hours, still more preferably 1 hour to 8 hours. As the concentration during mixing, the solid component is preferably 0.01 g / mL to 0.04 g / mL, more preferably 0.015 g / mL to 0.035 g / mL, still more preferably 0.02 g / mL to 0.035 g / mL.

[0074] (2) Mixing of the aluminoxane compound (c) and the compound (e) represented by the general formula (I), general formula (II) or general formula (III) One or more aluminoxane compounds (c) containing trialkylaluminum and an organic compound (e) represented by the general formula (I), general formula (II) or general formula (III) are mixed in an inert hydrocarbon solvent to obtain an aluminoxane compound-modified composition (B). Here, it is considered that the reaction described in the above [I] 7. (2) occurs.

[0075] A method of mixing and reacting one or more alumoxane compounds (c) containing trialkylaluminum and an organic compound (e) represented by the general formula (I), general formula (II) or general formula (III) in an inert hydrocarbon solvent is not particularly limited in the same manner as in the above [II] 2. (1). At this time, the amount (mol) of the organic compound (e) represented by the general formula (I), general formula (II) or general formula (III) with respect to the amount (mol) of aluminum atoms present in the alumoxane compound is 0.01 to 0.5 in molar ratio, preferably 0.03 to 0.3, more preferably 0.05 to 0.1, and they are mixed to obtain an alumoxane compound modified composition (B). Also, the temperature during mixing is preferably -20°C to 150°C, more preferably -10°C to 100°C, still more preferably 0°C to 80°C, and the mixing time is preferably 5 minutes to 12 hours, more preferably 30 minutes to 10 hours, still more preferably 1 hour to 8 hours. The inert hydrocarbon solvent used here includes the same solvents as in the above [II] 2. (1). As the concentration during mixing, based on the amount (mol) of aluminum atoms contained in the alumoxane compound before mixing, it is preferably 0.1 mmol / L to 1.5 mmol / L, more preferably 0.5 mmol / L to 1.4 mmol / L, still more preferably 0.8 mol / L to 1.2 mol / L.

[0076] 3. Step (c) Mixing of the chromium catalyst (A) and the alumoxane compound modified composition (B) The chromium catalyst (A) obtained in the above step (a) and further the alumoxane compound modified composition (B) obtained in the above step (b) are mixed in an inert hydrocarbon solvent.

[0077] As a method for mixing the chromium catalyst (A) according to the present invention and the aluminoxane compound-modified composition (B), if it is a method of mixing in an inert hydrocarbon, it is not particularly limited. For example, the chromium catalyst (A) is mixed with an inert hydrocarbon solvent such as propane, n-butane, isobutane, n-pentane, isopentane, hexane, heptane, octane, decane, cyclohexane, benzene, toluene, xylene, etc. to form a slurry state, and a solution of the aluminoxane compound-modified composition (B) is added thereto. This method is preferred. The aluminoxane compound-modified composition (B) to be added may be diluted with the above inert hydrocarbon solvent or added without dilution. The solvent for dilution and the solvent for contact may be the same or different.

[0078] The amount of the inert hydrocarbon solvent used is preferably an amount that allows stirring at least in a slurry state during mixing. With such an amount, the amount of the solvent used is not particularly limited, but for example, 2 to 20 g of the solvent can be used per 1 g of the chromium catalyst (A) after calcination activation.

[0079] In the aluminoxane compound-modified composition (B) according to the present invention, the molar ratio (Al / Cr) of the aluminum atom in the aluminoxane compound-modified composition (B) to the chromium atom in the chromium catalyst (A) is preferably 0.01 to 5, more preferably 0.05 to 4, and even more preferably 0.1 to 3. By setting it within this range, it is considered that the induction time can be shortened and the amount of by-product branches contained in the ethylene polymer can be reduced to suppress a decrease in density as compared with the case where the aluminoxane compound-modified composition (B) is not used. If this molar ratio is in the range of 0.01 to 5, the effect of using the aluminoxane compound-modified composition (B) is sufficiently exhibited, which is preferable. As the concentration at the time of mixing the aluminoxane compound-modified composition (B) and the chromium catalyst (A), the concentration of the chromium catalyst (A) is preferably 0.01 g / mL to 0.3 g / mL, more preferably 0.05 g / mL to 0.2 g / mL, and even more preferably 0.1 g / mL to 0.2 g / mL. Also, the temperature during mixing is preferably -20°C to 150°C, more preferably -10°C to 100°C, still more preferably 0°C to 80°C, and the mixing time is preferably 5 minutes to 12 hours, more preferably 30 minutes to 10 hours, still more preferably 1 to 8 hours.

[0080] 4. Any operations other than steps (a) to (c) In the method for producing a catalyst for ethylene polymerization according to the present invention, before the loading of the chromium compound (b) in step (a) or after the loading of the chromium compound (b) and before the calcination activation, metal alkoxides such as titanium tetra-isopropoxide, zirconium alkoxides such as zirconium tetra-butoxide, aluminum alkoxides such as aluminum tri-butoxide, fluorine-containing salts such as organometallic compounds and ammonium fluorosilicate, etc. may be added, and known methods for adjusting the ethylene polymerization activity, copolymerizability with α-olefins, molecular weight and molecular weight distribution of the obtained polyethylene may be used in combination. These metal alkoxides or organometallic compounds, etc., by calcination activation in a non-reducing atmosphere, the organic group part burns and is oxidized to metal oxides such as titania, zirconia, alumina and is contained in the catalyst. Also, in the case of fluorine-containing salts, the inorganic oxide carrier is fluorinated. These methods are described, for example, in the following references. (i) C.E. Marsden, Plastics, Rubber and Composites Processing and Applications, Volume 21, page 193, 1994 (ii) T. Pullukat et al., J. Polym. Sci., Polym. Chem. Ed., Volume 18, page 2857, 1980 (iii) M.P. McDaniel et al., J. Catal., Volume 82, page 118, 1983

[0081] [IV] Method for producing ethylene polymer 1. Method for producing ethylene polymer By using the ethylene polymerization catalyst produced by the production method of the present invention, an ethylene polymer excellent in the balance between moldability, rigidity (density) and durability can be obtained. That is, one aspect of the present invention also relates to a method for producing an ethylene polymer, characterized by carrying out homopolymerization of ethylene or copolymerization of ethylene and an α-olefin using the ethylene polymerization catalyst obtained by the above method.

[0082] When producing an ethylene polymer using the chromium catalyst produced by the production method of the present invention, any method such as 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, an inactive hydrocarbon such as propane, n-butane, isobutane, n-pentane, isopentane, hexane, heptane, octane, decane, cyclohexane, benzene, toluene, xylene or the like alone or as a mixture is used. In addition, for the gas phase polymerization method, a commonly known polymerization method such as a fluidized bed or a stirred bed can be employed in the presence of an inert gas, and in some cases, a so-called condensing mode in which a medium for removing the heat of polymerization coexists can also be employed.

[0083] The polymerization temperature in the liquid phase or gas phase polymerization method is generally 0°C to 300°C, practically 20°C to 200°C, preferably 50°C to 180°C, more preferably 70°C to 150°C. The catalyst concentration and ethylene concentration in the reactor may be at any concentration in promoting the polymerization. For example, in the case of liquid phase polymerization, based on the mass of the reactor contents, the catalyst concentration can preferably be in the range of 0.0001 to 5% by mass. Similarly, in the case of gas phase polymerization, the ethylene concentration can preferably be in the range of 0.1 to 10 MPa as the total pressure.

[0084] In order to increase the HLMFR (high load melt flow rate, temperature 190°C, load 21.6 kg) of the ethylene polymer, hydrogen may be coexisted and polymerized in particular. By coexisting hydrogen, the polymerization temperature can be lowered and the molecular weight distribution can be further broadened.

[0085] As the polymerization method according to the present invention, not only single-stage polymerization for producing polyethylene using one reactor, but also multi-stage polymerization can be carried out by connecting at least two reactors to broaden the molecular weight distribution. In the case of multi-stage polymerization, two reactors are connected, and two-stage polymerization in which the reaction mixture obtained by polymerization in the first-stage reactor is continuously supplied to the second-stage reactor is preferred. The transfer from the first-stage reactor to the second-stage reactor is carried out by continuously discharging the polymerization reaction mixture from the first-stage reactor through a connecting pipe by differential pressure.

[0086] In the method for producing an ethylene polymer according to the present invention, an α-olefin can also be copolymerized as a comonomer. The α-olefin is preferably an α-olefin having 3 to 8 carbon atoms. Specific examples include propylene, 1-butene, 1-hexene, 4-methyl-1-pentene, 1-octene, etc., which can be introduced into the reactor alone or in combination of two or more to carry out copolymerization. More preferably, 1-butene, 1-hexene, and particularly preferably 1-hexene are suitably used as the comonomer. The α-olefin content in the obtained copolymer is preferably 15 mol% or less, more preferably 10 mol% or less. According to the method for producing an ethylene polymer according to the present invention, copolymerization by a by-product component that generates a by-product branch is suppressed, and a copolymer of ethylene and α-olefin with a balance between the comonomer content and the physical properties of the polymer controlled can be obtained.

[0087] 2. Physical properties and uses of ethylene polymers By using the ethylene polymerization catalyst obtained by the method for producing an ethylene polymerization catalyst according to the present invention, the HLMFR is preferably 0.1 g / 10 min to 200 g / 10 min, more preferably 0.5 g / 10 min to 80 g / 10 min, and the density is preferably 0.900 g / cm 3 ~0.980 g / cm 3 , more preferably 0.920 g / cm 3 ~0.970 g / cm 3 An ethylene polymer is obtained. The obtained ethylene polymer has high impact resistance and durability and is excellent in balance, so it exhibits great effects especially in blow-molded products, particularly large blow-molded products. Furthermore, when forming a composition with other polyethylene resins, it exhibits high melt tension. The HLMFR of the ethylene polymer for blow-molded products is 1 g / 10 min to 100 g / 10 min, and particularly for the ethylene polymer for large blow-molded products, it is 1 g / 10 min to 15 g / 10 min. The density of the ethylene polymer for blow-molded products is 0.935 g / cm 3 ~0.970 g / cm 3 and particularly, the density of the ethylene polymer for large blow-molded products is preferably in the range of 0.940 g / cm 3 ~0.955 g / cm 3 .

Examples

[0088] Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples to demonstrate the superiority of the present invention and the advantages due to the configuration of the present invention, but the present invention is not limited by these examples. (I) Various measurement methods In Examples and Comparative Examples, the measurement methods used are as follows. (i) Polymer pretreatment for physical property measurement: As an additive, 0.2% by weight of "IRGANOX B225", which is a blend of an antioxidant and a phosphorus-based stabilizer manufactured by BASF Japan, was added, kneaded with a single-screw extruder, and pelletized. (ii) High load melt flow rate (HLMFR): According to Appendix A Table 1 - Condition G of JIS K7210 (2004 edition), the measured value at a test temperature of 190 °C and a nominal load of 21.60 kg was shown as the HLMFR. (iii) Density It was measured according to JIS K7112 (2004 edition). (iv) Method for determining butyl branches The amount of butyl branches (1 / 1000C; the number of butyl branches contained per 1000 carbon atoms) in the polyethylene sample was calculated by nuclear magnetic resonance absorption method (NMR method). [Sample Preparation and Measurement Conditions] 100 mg of the sample was placed in an NMR sample tube with an inner diameter of 10 mm φ together with 2.4 ml of o-dichlorobenzene / deuterated bromobenzene (C6D5Br) = 2 / 1 (volume ratio) and hexamethyldisiloxane, which is a chemical shift reference substance, and dissolved. The NMR measurement was performed using an AVANCE400 type NMR apparatus of Bruker BioSpin Corporation equipped with a 10 mm φ cryoprobe. 13 The 13C-NMR measurement conditions were as follows: sample temperature 120 °C, pulse angle 45°, pulse interval 2.76 seconds, number of integrations 10240 times, and measurement was carried out by the broadband decoupling method. The chemical shift was set with the 13C signal of hexamethyldisiloxane at 1.98 ppm, and the chemical shifts of signals due to other 13C were referenced to this. 13 13 [Calculation Method] Using the 13C-NMR spectrum obtained under the above measurement conditions, the butyl branching amount per 1000 carbons was determined from the following formula. 13 Butyl branching amount = I(B4) × 1000 / I(total) Here, I(B4) and I(total) are the amounts represented by the following formulas. I(B4) = (Correction factor 2B4 × I + Correction factor 4B4 × I 23.2~23.4 + 34.0~34.2 ) / 2 I(total) = Correction factor total × I 10.0~50.0 I represents the integrated intensity, and the numerical subscript of I indicates the chemical shift range. For example, I 23.2~23.4 represents the integrated intensity of the 13C signal detected between 23.2 and 23.4 ppm. The correction factors 2B4, 4B4, and total are the values obtained by the method described in JP 2019-144051 A (Claim 1 or Claim 2). Also, correction factor total × I 13 means the sum of the intensities obtained by multiplying each correction factor by the integrated intensity of each signal detected between 10.0 and 50 ppm. 10.0~50.0 (II) Examples and Comparative Examples

[0089] ​​​​ [Example 1] (1) Step (b): Preparation of the aluminoxane compound-modified composition (B) 5.0 g of Grace silica (SP9-496) as the inorganic solid component (d) having a hydroxyl group was weighed, heated at 200 °C for 2 hours, and then further heated at 400 °C for 6 hours (the amount of OH in the dried silica was 1.6 mmol-OH / g). It was cooled under a nitrogen atmosphere, and 1.6 g was taken out. 20 mL of dehydrated hexane was added thereto to prepare a slurry. To this slurry, 30 mL of MMAO-3A (containing trimethylaluminum and triisobutylaluminum, with a total aluminum atom concentration of 1.5 mol / L, hexane solution) manufactured by Tosoh Finechem Corporation as the aluminoxane compound (c) was added, and the mixture was stirred at 20 °C for 1 hour. Then, the solid content was removed by decantation, and 30 mL of the supernatant was recovered to obtain the aluminoxane compound-modified composition (B) (dMMAO solution). In this reaction, the molar ratio ([OH] / [Al]) of the amount of OH groups contained in the silica to the amount of aluminum atoms contained in the aluminoxane compound was 0.057. As a result of calculating the aluminum concentration in the obtained dMMAO solution by ICP measurement, it was 0.78 mol / L.

[0090] (2) Step (a): Preparation of the chromium catalyst (A) 10 g of silica as the inorganic oxide carrier (a) was added to a chromium acetate ethanol solution prepared by dissolving 0.44 g of chromium acetate as the chromium compound (b) in 50 ml of ethanol, stirred for 10 minutes, and then ethanol was distilled off to obtain chromium-containing silica with a chromium atom loading of 1.0 wt%. This chromium-containing silica had a specific surface area of 380 m 2 / g and a pore volume of 1.55 cm 3 / g. Then, this chromium-containing silica was placed in a quartz glass tube with a diameter of 5 cm equipped with a porous plate and a mesh dish, set in a cylindrical firing electric furnace, fluidized with air passed through molecular sieves, and fired and activated at a linear velocity of 3 cm / s and 500 °C for 18 hours. As a result, an orange chromium catalyst (A) containing hexavalent chromium atoms was obtained.

[0091] (3) Step (C): Preparation of an organometallic compound-supported chromium catalyst (Catalyst-1) 2.0 g of the chromium catalyst obtained in the above (2) was placed in a 100 mL flask previously purged with nitrogen, and 14 mL of hexane purified by distillation was added thereto to form a slurry. 1.0 mL (Al / Cr molar ratio = 2.0) of the dMMAO solution, which is the aluminoxane compound-modified composition (B) obtained in the above (1), was added thereto, and the mixture was stirred at 40 °C for 1 hour. Immediately after completion of the stirring, the solvent was removed under reduced pressure over 30 minutes to obtain a free-flowing organometallic compound-supported chromium catalyst (Catalyst-1) having no viscosity or stickiness.

[0092] (4) Ethylene polymerization evaluation 87.9 mg of the Catalyst-1 obtained in the above (3) and 0.7 L of isobutane were charged into a 2.0 L autoclave sufficiently purged with nitrogen, and the internal temperature was raised to 100 °C. Then, ethylene was pressured in, and polymerization was carried out for 52 minutes starting from the time when the ethylene absorption amount reached 40 g / hr or more while maintaining the ethylene partial pressure at 1.4 MPa. At this time, the time from when the ethylene partial pressure reached 1.4 MPa until the ethylene absorption amount reached 40 g / hr was defined as the induction time. The induction time was 4 minutes. The polymerization was stopped by discharging the internal gas out of the system. The polymerization results and polymer physical properties are shown in Tables 1 and 2.

[0093] [Example 2] (1) Step (b): Preparation of an aluminoxane compound-modified composition (B) Dissolve 500 mg (2.27 mmol) of 3,5-Di-tert-butyl-4-hydroxytoluene (BHT) as organic compound (e) in 10 mL of hexane, add 20 mL of MMAO-3A manufactured by Tosoh Finechem Co., Ltd. used in Example 1(1) thereto, and stir at 20 °C for 1 hour. At this time, the amount of organic compound (e) with respect to the aluminum atoms contained in MMAO was 0.076 in molar ratio. As a result, an MMAO-BHT solution was obtained as the aluminoxane compound-modified composition (B). The obtained solution was used as an MMAO-BHT solution with an aluminum atom concentration of 1.0 mol / L (the concentration was determined as the concentration diluted with the solvent used based on MMAO-3 before the reaction).

[0094] (2) Step (a): Preparation of Chromium Catalyst (A) The chromium catalyst (A) obtained from Example 1(2) above was used. (3) Step (c): Preparation of Chromium Catalyst (Catalyst-2) In Example 1(3) above, the same operation as in Example 1(3) was carried out except that 0.77 mL of the MMAO-BHT solution obtained from (2) above (Al / Cr molar ratio = 2) was used instead of the dMMAO solution, and a chromium catalyst (Catalyst-2) was obtained. (4) Ethylene Polymerization Evaluation In Example 1(4) above, polymerization was carried out in the same manner as in Example 1(4) except that 81.8 mg of Catalyst-2 was used instead of Catalyst-1 and the polymerization time was 58 minutes. At this time, the induction time was 10 minutes. The polymerization results and polymer physical properties are shown in Tables 1 and 2.

[0095] [Comparative Example 1] (1) Step (b): Preparation of Aluminoxane Compound-Modified Composition (B) Not carried out. (2) Step (a): Preparation of Chromium Catalyst (A) The chromium catalyst (A) obtained from Example 1(2) above was used. (3) Step (c): Preparation of Chromium Catalyst (Catalyst-2) Not carried out. (4) Ethylene Polymerization Evaluation 95.3 mg of the chromium catalyst (A) obtained from the above Example 1(2) was used, and in Example 1(4), polymerization was carried out in the same manner as in Example 1(4) except that the polymerization time was 56 minutes. The induction time at this time was 33 minutes. The polymerization results and polymer physical properties are shown in Tables 1 and 2.

[0096] [Comparative Example 2] (1) Step (b): Preparation of the aluminoxane-based compound-modified composition (B) Not carried out. (2) Step (a): Preparation of the chromium catalyst (A) The chromium catalyst (A) obtained from Example 1(2) was used. (3) Step (c): Preparation of the chromium catalyst (Catalyst-3) In the above Example 1(3), the same operation as in Example 1(3) was carried out except that 0.51 mL (Al / Cr molar ratio = 2) of MMAO-3A manufactured by Tosoh Finechem Corporation used in Example 1(1) was used instead of dMMAO to obtain the chromium catalyst (Catalyst-3). (4) Ethylene polymerization evaluation 91.1 mg of the catalyst-3 obtained from the above (3) was used, and polymerization was carried out in the same manner as in Example 1(4) above except that the polymerization time was 56 minutes. The induction time at this time was 2 minutes. The polymerization results and polymer physical properties are shown in Tables 1 and 2.

[0097]

Table 1

[0098]

Table 2

[0099] As can be seen from Tables 1 and 2, when Example 1 is compared with Comparative Example 1, although the butyl branching is low in Comparative Example 1, the induction time was significantly shortened in Example 1 using a chromium catalyst with an aluminoxane compound-modified composition (B). Similarly, when Example 2 is compared with Comparative Example 1, the induction time was shortened in Example 2 using a chromium catalyst with an aluminoxane compound-modified composition (B). Further, when Example 1 is compared with Comparative Example 2, the induction times are almost the same, but in Example 1 using a chromium catalyst with an aluminoxane compound-modified composition (B), the butyl branching decreased by half and the density decrease was suppressed. When Example 2 is compared with Comparative Example 2, while maintaining the shortening of the induction time, the butyl branching decreased to less than half in Example 2 using a chromium catalyst with an aluminoxane compound-modified composition (B), and the density decrease was suppressed. From the above, it was shown that the chromium-supported catalyst obtained by the production method disclosed in the present invention according to the examples and comparative examples has a short induction time and is useful in the production of high-density ethylene polymers.

Claims

1. A method for producing a catalyst for ethylene polymerization, characterized by comprising the following steps (a) to (c), wherein in the following step (b), the amount of the following inorganic oxide (d) used is 0.01 to 0.5 in terms of the molar ratio ([OH] / [Al]) of the hydroxyl group contained in the following inorganic oxide (d) to the aluminum atom contained in the following aluminoxane compound (c). A method for producing a catalyst for ethylene polymerization. Step (a): A step of supporting a chromium compound (b) on an inorganic oxide carrier (a) and subjecting it to calcination activation in a non-reducing atmosphere to obtain a chromium catalyst (A). Step (b): At least one aluminoxane compound (c) containing trialkylaluminum and an inorganic oxide (d) having a hydroxyl group, an average particle size of 10 μm to 200 μm, and a specific surface area of 100 m 2 / g to 900 m 2 / g, and the amount of the hydroxyl group is 0.1 mmol-OH / g to 10 mmol-OH / g. A step of mixing them to obtain an aluminoxane compound-modified composition (B). Step (c): A step of mixing the chromium catalyst (A) and the aluminoxane compound-modified composition (B) in an inert hydrocarbon solvent.

2. A method for producing a catalyst for ethylene polymerization, characterized by comprising the following steps (a) to (c), wherein in the following step (b), the amount of the following organic compound (e) used is 0.01 to 0.5 in terms of the molar ratio to the aluminum atom contained in the following aluminoxane compound (c). A method for producing a catalyst for ethylene polymerization. Step (a): A step of supporting a chromium compound (b) on an inorganic oxide carrier (a) and subjecting it to calcination activation in a non-reducing atmosphere to obtain a chromium catalyst (A). Step (b): A step of mixing at least one aluminoxane compound (c) containing trialkylaluminum and at least one organic compound (e) represented by the following general formula (I) to obtain an aluminoxane compound-modified composition (B). Step (c): A step of mixing the chromium catalyst (A) and the aluminoxane compound-modified composition (B) in an inert hydrocarbon solvent. 【Chemical 1】 [In formula (I), X 1 represents an oxygen atom. R1 represents a hydrocarbon group having 1 to 30 carbon atoms, and the hydrocarbon group may have a substituent containing a heteroatom selected from an oxygen atom, a sulfur atom, a nitrogen atom, a phosphorus atom, a silicon atom, a halogen atom, an aluminum atom or a boron atom. When there are a plurality of R1s, each R1 may be the same or different, and may crosslink at an arbitrary position to form a cyclic structure. m represents the valence of X1. n represents 1.

3. In the general formula (I), the R １ wherein the hydrocarbon group having 1 to 30 carbon atoms has an aryl group, and the method for producing a catalyst for ethylene polymerization according to any one of claims 1 to 2.

4. The method for producing a catalyst for ethylene polymerization according to any one of claims 1 to 3, characterized in that the alumo-xane compound (c) has a methylaluminum structure and an alkylaluminum structure other than the methylaluminum structure.

5. The method for producing a catalyst for ethylene polymerization according to claim 4, characterized in that the alkylaluminum structure is an isobutylaluminum structure.

6. A method for producing an ethylene polymer or a copolymer of ethylene and an α-olefin, characterized by comprising the method for producing a catalyst for ethylene polymerization according to any one of claims 1 to 5.

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