JP2020063434A - Ethylenic polymerization catalyst, and method for producing ethylenic polymer - Google Patents

Abstract

To provide an ethylenic polymerization catalyst capable of producing an ethylenic polymer having an ultrahigh molecular component.SOLUTION: An ethylenic polymerization catalyst contains a chromium catalyst A1. The chromium catalyst A1 is obtained by supporting a chromium compound C1 on inorganic oxide particles B1, and the particle shape is a plate shape. The inorganic oxide particles B1 preferably contain particles of SiOas a main component. An average value of plate thickness T (nm) of particles of the chromium catalyst A1 is preferably 1 nm or more and 100 nm or less. When the ethylenic polymerization catalyst is used, an ethylenic polymer having an ultrahigh molecular component is obtained compared to the case in which a conventional ethylenic polymerization catalyst is used in which a chromium compound is supported on amorphous inorganic oxide particles.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an ethylene-based polymerization catalyst and a method for producing an ethylene-based polymer. More specifically, it relates to an ethylene-based polymerization catalyst capable of producing an ultra-high molecular weight ethylene-based polymer, and a method for producing an ethylene-based polymer.

The ethylene polymer is a basic material that represents a plastic material in the industrial field. Since ethylene-based polymers are widely used in a great number of technical fields, various properties such as molecular weight distribution and fluidity, and mechanical properties and thermal properties are required depending on the application and molding method. Has a wide range of performance.
In order to produce such an ethylene-based polymer, various polymerization catalysts have been developed and improved. Among them, the Phillips catalyst is often used together with the Ziegler catalyst and the metallocene catalyst. The Phillips catalyst is obtained by supporting a chromium compound on an inorganic oxide carrier such as silica, silica-alumina, or silica-titania and activating it in a non-reducing atmosphere so that at least a part of the supported chromium atoms is 6 atoms. Valent chromium catalyst. With the Phillips catalyst, an ethylene-based polymer having a relatively wide molecular weight distribution is obtained, and generally has good moldability and is used for blow molding and the like.

  Creep resistance and impact resistance are important properties in large blow molded products. When an ethylene polymer having a wide molecular weight distribution obtained by a conventional Phillips catalyst is blow molded into a large product or the like, the molded product does not always have a sufficient balance between creep resistance and impact resistance. Creep resistance and impact resistance are contradictory physical properties, and generally speaking, when creep resistance improves, impact resistance decreases, and conversely, when impact resistance improves, creep resistance decreases. .

Therefore, if an ethylene polymer having excellent physical properties such as creep resistance and moldability can be obtained in the Phillips catalyst, it becomes a material having a good balance of physical properties and moldability over conventional levels. However, a precise catalyst control method that uses a Phillips catalyst to introduce a long chain branch of an appropriate length into an appropriate molecular weight region in an appropriate amount is difficult with the technology at the present stage. No specific guideline has yet been obtained on how to improve both.
As an attempt to obtain an ethylene polymer having a good balance of physical properties and moldability using a Phillips catalyst, studies using a carrier having a specific structure have been conducted. For example, Patent Documents 1 and 2 disclose the use of highly porous silica having a specific surface area, average pore volume, and average pore diameter. Further, Patent Literature 3 discloses a technique of broadening the molecular weight distribution of a polymer by combining a Phillips catalyst obtained from silica having a specific structure with an organoaluminum compound. Further, Patent Document 4 discloses the use of silica having a unique pore structure and crystallinity.
However, it is difficult to control the molecular weight distribution and composition distribution of the polymer with these catalysts, and it has not been possible to design the catalyst so as to express the target material properties.

Therefore, attempts have been made to polymerize the high molecular weight component and the low molecular weight component with separate catalysts. For example, by producing a high molecular weight component having a high molecular weight and a wide molecular weight distribution, and simultaneously producing a low molecular weight component having a low molecular weight and a narrow molecular weight distribution, it is possible to increase the high molecular weight component and decrease the low molecular weight component. It is possible to improve both creep resistance and impact resistance. From such a viewpoint, Patent Document 5 discloses that a high molecular weight polyethylene can be obtained by a Phillips catalyst using a clay mineral as a carrier. Further, Patent Documents 6 and 7 disclose that the molecular weight distribution of the obtained polymer can be controlled by combining clay mineral and ordinary silica.
Thus, although various catalysts have been developed and various ethylene-based polymers have been synthesized, the desired effects may not be obtained in some cases with the ethylene-based polymers produced using the existing catalysts. Therefore, an ethylene polymer having an ultrahigh molecular weight component is desired as one of the variations of the ethylene polymer.

Japanese Patent Publication No. 2002-533536 Japanese Patent No. 5821746 Japanese Patent Publication No. 2006-512454 Japanese Patent Publication No. 2007-517962 JP, 2006-257255, A JP, 2008-150566, A International Publication No. 2002/088196

  The present invention has been made in view of the above circumstances, and an object thereof is to provide an ethylene-based polymerization catalyst capable of producing an ethylene-based polymer having an ultrahigh molecular weight component. Another object of the present invention is to provide a method for producing an ethylene-based polymer capable of producing an ethylene-based polymer having an ultrahigh molecular weight component. The present inventors, in order to solve the above problems, as a result of repeated intensive research, by using an ethylene-based polymerization catalyst having a specific form, it was found that it is possible to produce an ethylene-based polymer having an ultrahigh molecular weight component, The present invention has been completed based on this finding. The present invention can be realized as the following modes.

[1] An ethylene-based polymerization catalyst containing a chromium catalyst A1,
The chromium catalyst A1 is an ethylene-based polymerization catalyst characterized in that the inorganic oxide particles B1 carry the chromium compound C1 and the particle shape is plate-like.

[2] The ethylene-based polymerization catalyst according to [1], wherein the inorganic oxide particles B1 are particles whose main component is SiO ₂ .

  [3] The ethylene-based polymerization catalyst according to [1] or [2], wherein the plate thickness T (nm) of the particles of the chromium catalyst A1 is 1 nm or more and 100 nm or less.

  [4] The average value of D / T, which is the ratio of the maximum diameter D (nm) of the particles of the chromium catalyst A1 to the plate thickness T (nm), is 10 or more, [3] Ethylene polymerization catalyst.

  [5] Any one of [1] to [4], which has a peak showing crystallinity in a half width of 0.2 ° or more and 5 ° or less at 2θ = 23 ° to 29 ° in powder X-ray diffraction. The ethylene-based polymerization catalyst according to item.

  [6] The ethylene-based polymerization catalyst according to any one of [1] to [5], wherein the content of chromium atoms is 0.01% by weight to 2.0% by weight.

  [7] The ethylene-based material according to any one of [1] to [6], further containing a chromium catalyst A2 in which a chromium compound C2 is supported on amorphous inorganic oxide particles B2. Polymerization catalyst.

[8] The inorganic oxide particles B2 are selected from the group consisting of particles having a main component of SiO ₂ , particles having a main component of SiO ₂ —TiO ₂ , and particles having a main component of SiO ₂ —Al ₂ O ₃ . The ethylene-based polymerization catalyst according to [7], which is composed of at least one kind of particles.

  [9] The ethylene-based polymerization catalyst according to [7] or [8], wherein the mixing ratio of the chromium catalyst A1 and the chromium catalyst A2 is 1:99 to 99: 1 by weight.

[10] The content of chromium atoms contained in the chromium catalyst A1 is 0.01% by weight to 2.0% by weight, and the content of chromium atoms contained in the chromium catalyst A2 is 0.01% by weight. % To 2.0% by weight, the ethylene-based polymerization catalyst according to any one of [7] to [9].

  [11] The ethylene-based polymerization as set forth in any one of [7] to [10], wherein the particles of the chromium catalyst A1 and the particles of the chromium catalyst A2 are combined to form combined particles. catalyst.

  [12] A method for producing an ethylene-based polymer, which comprises polymerizing a monomer containing at least ethylene using the ethylene-based polymerization catalyst according to any one of [1] to [11].

[13] An ethylene-based polymerization catalyst containing a chromium catalyst A1,
An ethylene-based polymerization catalyst, wherein the chromium catalyst A1 contains agglomerated particles obtained by aggregating a structure in which a chromium compound C1 is supported on plate-like inorganic oxide particles B1.

[14] The ethylene-based polymerization catalyst according to [13], wherein the inorganic oxide particles B1 are particles whose main component is SiO ₂ .

  [15] The ethylene-based polymerization catalyst according to [13] or [14], wherein the average particle thickness T (nm) of the particles of the chromium catalyst A1 is 1 nm or more and 100 nm or less.

  [16] The average value of D / T, which is the ratio of the maximum diameter D (nm) of the particles of the chromium catalyst A1 to the plate thickness T (nm), is 10 or more, [15] Ethylene polymerization catalyst.

  [17] Any one of [13] to [16], which has a peak exhibiting crystallinity in a half width of 0.2 ° or more and 5 ° or less at 2θ = 23 ° to 29 ° in powder X-ray diffraction. The ethylene-based polymerization catalyst according to item.

  [18] The ethylene-based polymerization catalyst according to any one of [13] to [17], wherein the content of chromium atoms is 0.01% by weight to 2.0% by weight.

  [19] The ethylene-based material according to any one of [13] to [18], which further comprises a chromium catalyst A2 in which a chromium compound C2 is supported on amorphous inorganic oxide particles B2. Polymerization catalyst.

[20] The inorganic oxide particles B2 are selected from the group consisting of particles having a main component of SiO ₂ , particles having a main component of SiO ₂ —TiO ₂ , and particles having a main component of SiO ₂ —Al ₂ O ₃ . The ethylene-based polymerization catalyst according to [19], which is composed of at least one kind of particles.

  [21] The ethylene-based polymerization catalyst according to [19] or [20], wherein the mixing ratio of the chromium catalyst A1 and the chromium catalyst A2 is 1:99 to 99: 1 by weight.

[22] The content of chromium atoms contained in the chromium catalyst A1 is 0.01% by weight to 2.0% by weight, and the content of chromium atoms contained in the chromium catalyst A2 is 0.01% by weight. % To 2.0% by weight, the ethylene-based polymerization catalyst according to any one of [19] to [21].

  [23] The ethylene-based polymerization as set forth in any one of [19] to [22], wherein the particles of the chromium catalyst A1 and the particles of the chromium catalyst A2 are bonded to each other to form bonded particles. catalyst.

  [24] A method for producing an ethylene polymer, which comprises polymerizing a monomer containing at least ethylene using the ethylene polymerization catalyst according to any one of [13] to [23].

By using the ethylene-based polymerization catalyst of the present invention, an ethylene-based polymer having an ultrahigh molecular weight component can be produced.
According to the method for producing an ethylene polymer of the present invention, an ethylene polymer having an ultrahigh molecular weight component can be produced.

It is a schematic diagram for demonstrating plate thickness T of particles of chromium catalyst A1, and D / T. It is an SEM image of chromium catalyst A1.

Hereinafter, the present invention will be described specifically and in detail for each item.
In addition, in the present specification, the description using “to” for the numerical range includes the lower limit value and the upper limit value unless otherwise specified. For example, the description “10 to 20” includes both the lower limit “10” and the upper limit “20”. That is, “10 to 20” has the same meaning as “10 or more and 20 or less”.

  The ethylene-based polymerization catalyst of the present invention contains at least the chromium catalyst A1. The ethylene-based polymerization catalyst may further contain a chromium catalyst A2. That is, the ethylene-based polymerization catalyst may contain the chromium catalyst A1 and the chromium catalyst A2.

1. Chromium catalyst A1
The chromium catalyst A1 is in any one of the following modes.
The chromium catalyst A1 can adopt a mode in which the chromium compound C1 is supported on the inorganic oxide particles B1 and the particle shape is a plate shape (first mode).
Alternatively, the chromium catalyst A1 can adopt a mode in which plate-shaped inorganic oxide particles B1 contain agglomerated particles obtained by aggregating a structure in which a chromium compound C1 is supported (second mode). In the case of the second aspect, the chromium catalyst A1 may be composed of only agglomerated particles. In the second aspect, [1] agglomerated particles obtained by aggregating the structure in which the chromium compound C1 is supported on the plate-shaped inorganic oxide particles B1 and [2] plate-shaped inorganic oxide particles B1. A structure in which the compound C1 is supported and particles that are not aggregated may be mixed.
The chromium catalyst A1 is a chromium catalyst in which at least a part of chromium atoms is hexavalent, and is classified into a catalyst generally called a Phillips catalyst.
Kazuo Matsuura, Naotaka Mikami, "Polyethylene Technology Handbook," p. 81, 2001 Industrial Research Committee, M.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.I. B. Welch et al. "Handbook of Polyolefins Synthesis and Properties" p. 21 (1993) Marcel Dekker et al. Give an overview of this catalyst.
The chromium catalyst A1 is generally produced by contacting the below-described chromium compound D with the inorganic oxide particles B1 (inorganic oxide carrier) and activating them in a non-reducing atmosphere.

(1) Inorganic oxide particles B1
In the present invention, the inorganic oxide particles B1 are used as the carrier.
The inorganic oxide particles B1 are particles whose main component is a metal oxide. Here, the main component means a substance having a content rate (% by weight) of 90% by weight or more. The content of the metal oxide in the inorganic oxide particles B1 may be 90% by weight or more, preferably 95% by weight or more, and more preferably 98% by weight or more. Of course, the content of the metal oxide may be 100% by weight.
The inorganic oxide constituting the inorganic oxide particles B1 is preferably an oxide of a metal of Group 2, 3, 4, 13 or 14 of the periodic table (periodic table according to the 1990 rule of nomenclature of inorganic compounds), and the specific silica _(SiO 2), silica - titania _(SiO 2 -TiO _2), silica - alumina _{(SiO 2 -Al 2 O 3)} , titania _(TiO 2), alumina _{(Al 2 O} 3), magnesia ( It is preferably selected from MgO), zirconia (ZrO ₂ ), and silica-zirconia (SiO ₂ —ZrO ₂ ). Among these, silica (SiO ₂ ) is preferable.
That is, in the inorganic oxide particles B1, the main component is a particle of silica (SiO ₂ ), the main component is a particle of silica-titania (SiO ₂ —TiO ₂ ), and the main component is silica-alumina (SiO ₂ —Al ₂ O _3). ) Particles, main component of titania (TiO ₂ ), main component of alumina (Al ₂ O ₃ ), main component of magnesia (MgO), main component of zirconia (ZrO ₂ ), and It is preferable that the main component is composed of at least one kind of particles selected from the group consisting of particles of silica-zirconia (SiO ₂ —ZrO ₂ ). In particular, from the viewpoint of ease of shape control of the inorganic oxide and catalytic performance, the inorganic oxide particles B1 are preferably particles whose main component is silica (SiO ₂ ).
The content of silica (SiO ₂ ) in the particles containing silica (SiO ₂ ) as a main component may be 90% by weight or more, preferably 95% by weight or more, and more preferably 98% by weight or more. Of course, the content of silica (SiO ₂ ) may be 100% by weight.
The total content of silica (SiO ₂ ) and titania (TiO ₂ ) in the particles whose main component is silica-titania (SiO ₂ —TiO ₂ ) may be 90 wt% or more, but 95 wt% or more is preferable, More preferably, it is 98% by weight or more. Of course, the total content of silica (SiO ₂ ) and titania (TiO ₂ ) may be 100% by weight.
The total content of silica (SiO ₂ ) and alumina (Al ₂ O ₃ ) in the particles whose main component is silica-alumina (SiO ₂ —Al ₂ O ₃ ) is 90% by weight or more, but 95% by weight. The above is preferable, and 98% by weight or more is further preferable. Of course, the total content of silica (SiO ₂ ) and alumina (Al ₂ O ₃ ) may be 100% by weight.
When particles having silica-titania (SiO ₂ —TiO ₂ ) as a main component are used, titanium atom is 0.2 wt% to 10 wt%, preferably 0.5 wt% to 7 wt% as a metal component. %, More preferably 1 wt% to 5 wt% particles are used.
When particles of silica-zirconia (SiO ₂ —ZrO ₂ ) are used as the main component, zirconium atom is 0.2 wt% to 10 wt%, preferably 0.5 wt% to 7 wt% as the metal component. %, More preferably 1 wt% to 5 wt% particles are used.
When particles of silica-alumina (SiO ₂ —Al ₂ O ₃ ) are used as the main component, aluminum atom is 0.2 wt% to 10 wt%, preferably 0.5 wt% to be the metal component. 7% by weight, more preferably 1% to 5% by weight of particles are used.

It is preferable that the inorganic oxide particles B1 have a peak exhibiting crystallinity in a half width of 0.2 ° or more and 5 ° or less at 2θ = 23 ° to 29 ° in powder X-ray diffraction. When the inorganic oxide particles B1 are crystalline, it is considered that the ethylene-based polymer has a high molecular weight due to the unique structure. An example of the unique structure is that it has active and highly reactive Si—OH groups at a high density (about 30 μmol / m ² ) on the surface or between layers.

The surface area of the inorganic oxide particles B1 is not particularly limited. From the viewpoint of supporting chromium atoms in a dispersed state, the surface area is preferably 10 m ² / g or more and 1000 m ² / g or less, more preferably 20 m ² / g or more and 500 m ² / g or less, and 50 m More preferably, it is ² / g or more and 400 m ² / g or less.

  The pore volume of the inorganic oxide particles B1 is not particularly limited. Since it has a plate-like structure, the pore volume is preferably 2.0 mL / g or less, more preferably 1.0 mL / g or less, and further preferably 0.5 mL / g or less. The lower limit of the pore volume is preferably 0.05 mL / g or more, more preferably 0.1 mL / g or more.

(2) Plate thickness T of particles of chromium catalyst A1
The plate thickness T (nm) of the particles of the chromium catalyst A1 is not particularly limited. From the viewpoint of maintaining the crystalline structure and maintaining the dispersibility in the polymer at the time of polymerization, the average value of the plate thickness T (nm) of the particles of the chromium catalyst A1 is preferably 1 nm or more and 100 nm or less, The thickness is more preferably 5 nm or more and 50 nm or less, further preferably 10 nm or more and 40 nm or less.
The average value of the plate thickness T (nm) of the particles of the chromium catalyst A1 is obtained by measuring the plate thickness T (nm) of 10 particles of the chromium catalyst A1 with a scanning electron microscope (SEM). Calculated by averaging. FIG. 1 is a schematic view of an SEM image when the particles of the chromium catalyst A1 are observed by a scanning electron microscope, and the plate thickness T (nm) is shown.

(3) Ratio D / T of maximum diameter D (nm) of particles of chromium catalyst A1 and plate thickness T (nm)
The average value of D / T, which is the ratio of the maximum particle diameter D (nm) of the chromium catalyst A1 to the plate thickness T (nm), is not particularly limited. From the viewpoint of existing as a plate-like structure in the particles, the average value of D / T is preferably 10 or more, more preferably 20 or more, and further preferably 30 or more. The upper limit of the average value of D / T is not particularly limited, but is usually 2000.
The average value of D / T is obtained by observing 10 particles of the chromium catalyst A1 with a scanning electron microscope (SEM). That is, the average value of D / T uses 10 particles of the chromium catalyst A1, and for each particle, D / T, which is the ratio of the maximum particle diameter D (nm) to the plate thickness T (nm), is calculated. It is obtained by calculating and averaging the values. FIG. 1 is a schematic view of an SEM image when the particles of the chromium catalyst A1 are observed by a scanning electron microscope, and the maximum diameter D (nm) is shown. From the maximum diameter D (nm) and the plate thickness T (nm) described above, the D / T of each particle can be obtained.
As described above, in the second embodiment, the chromium catalyst A1 is plate-shaped particles and also includes particles in which plate-shaped particles are aggregated. The plate-like particles are primary particles. The powder generally exists as aggregates called pseudo particles or aggregates such as secondary particles in which a plurality of primary particles are aggregated and tertiary particles in which a plurality of secondary particles are aggregated. Similarly, the chromium catalyst A1 of the present invention includes those present as aggregates.

(4) Chromium compound C1
The chromium compound C1 is not particularly limited as long as it is a chromium compound in which at least some chromium atoms are hexavalent. For example, the chromium compound C1 is chromium oxide, chromium halide, oxyhalide, chromate, dichromate, nitrate, carboxylate, sulfate, chromium-1,3-diketo compound, chromate ester, etc. (Hereinafter, the trivalent chromium compounds such as chromium oxide to chromate ester listed here are also referred to as "chromium compound D"). After being supported on the inorganic oxide particles B1, the chromium compound D is activated in the non-reducing atmosphere to become the chromium compound C1. The hexavalent chromium compound C1 may be directly supported on the inorganic oxide particles B1.
As the chromium compound D, more specifically, chromium (III) oxide, chromium trichloride, chromyl chloride, potassium chromate, ammonium chromate, potassium dichromate, chromium nitrate, chromium sulfate, chromium acetate, tris (2- Examples include ethylhexanoate) chromium, chromium acetylacetonate, and bis (tert-butyl) chromate. Particularly, as the chromium compound D, chromium (III) oxide, chromium acetate, and chromium acetylacetonate are preferable.
Even when a chromium compound having an organic group such as chromium acetate or chromium acetylacetonate is used, the organic group portion is burned by activation in a non-reducing atmosphere described later, and finally chromium oxide ( It is known that, as in the case of using III), it reacts with the hydroxyl groups on the surface of the inorganic oxide carrier, and at least some of the chromium atoms become hexavalent and are immobilized in the structure of chromate ester ( V. J. Ruddic et al .; J. Phys. Chem. Vol. 100 p. 11062 (1996), SM Augustin et al .; J. Catal. Vol. 161 p. 641 (1996)).

(5) Content of Chromium Atom in Chromium Catalyst A1 The content of chromium atom in the chromium catalyst A1 is not particularly limited. The content of chromium atoms is preferably 0.01% by weight to 2.0% by weight from the viewpoint that the chromium atoms to be carried do not aggregate with each other and are efficiently activated. It is more preferably from 1% by weight to 2% by weight, further preferably from 0.2% by weight to 1.5% by weight.

(6) Supporting Chromium Compound D on Inorganic Oxide Particles B1 In order to support the above chromium compound D on the inorganic oxide particles B1, the following method can be adopted. Suitable examples are a method of impregnating the inorganic oxide particles B1 with a solution of a chromium compound D and then distilling off the solvent, and a method of sublimating the chromium compound D without using the solvent. Also, other known methods can be adopted. The supporting method is appropriately selected depending on the type of the chromium compound D used.
In addition, the inorganic oxide particles B1 carrying the chromium compound D may be directly obtained by using a raw material to which the chromium compound D has been added in advance during the production of the inorganic oxide particles B1.

(7) Activation The inorganic oxide particles B1 carrying the chromium compound D are fired in an activation furnace for activation. The activation is performed in a non-reducing atmosphere that does not substantially contain water. For example, it is performed under oxygen or air, but an inert gas may coexist. Preferably, it is carried out in a fluidized state by using molecular sieves or the like in circulation and sufficiently dried air.
The activation temperature is not particularly limited. The activation temperature is preferably 350 ° C to 900 ° C, more preferably 400 ° C to 850 ° C. The time for activation is not particularly limited. The time for activation is preferably 30 minutes to 48 hours, more preferably 1 hour to 35 hours, still more preferably 2 hours to 30 hours. By activation, at least a part of the chromium atoms of the chromium compound D supported on the inorganic oxide particles B1 is oxidized to be hexavalent, and as described above, the chromium compound C1 is chemically fixed on the inorganic oxide particles B1. To be done.

When supporting or activating the chromium compound D, a fluorine compound such as ammonium silicofluoride or ammonium monohydrogen difluoride, titanium alkoxides such as titanium tetraisopropoxide, zirconium alkoxides such as zirconium tetrabutoxide, and aluminum trioxide. Aluminum alkoxides such as butoxide, organoaluminums exemplified by trialkylaluminums, metal alkoxides represented by organomagnesiums exemplified by dialkylmagnesium, or organometallic compounds are added to obtain ethylene polymerization activity or You may use together the well-known method which adjusts the molecular weight and molecular weight distribution of the obtained ethylene polymer.
In these metal alkoxides or organometallic compounds, by activation in a non-reducing atmosphere, the organic group portion is burned, oxidized to a metal oxide such as titania, zirconia, alumina or magnesia, and contained in the catalyst. . Further, the fluorine compound fluorinates the inorganic oxide carrier by thermally decomposing at the time of activation.
These methods are described in C.I. E. Marsden; Plastics, Rubber and Composites Processing and Applications Vol. 21 p. 193 (1994), T.W. Pullukat et al. J .; Polym. Sci. , Polym. Chem. Ed. Vol. 82 p. 118 (1980), M.A. P. McDaniel et al. J .; Catal. Vol. 82 p. 118 (1983), etc., for the outline or details.

The activation temperature and time are adjusted so that the chromium atoms contained in the chromium catalyst A1 are usually oxidized to 50 to 100% by weight, preferably 60 to 100% by weight, by activation.
The total amount of chromium atoms can be usually measured by a general metal analysis method such as plasma emission analysis or fluorescent X-ray method. Although the valence of chromium can be roughly estimated by observing the color change of a solid product (generally, hexavalent is yellow to orange, trivalent is green, and divalent is blue) by visual observation. The chelate titration method and the absorptiometry method are known as simple methods for quantitative determination. Specifically, “Chemical Chemistry Lecture 15 Analysis” edited by The Chemical Society of Japan, Maruzen (1991), p. 246-248. For example, in the case of trivalent chromium, an excess concentration of EDTA (ethylenediaminetetraacetic acid) of known concentration is added to trivalent chromium in an acidic solution, and the mixture is boiled for 5 to 10 minutes. It can be quantified by titrating. In the case of hexavalent chromium, it can be quantified by measuring the absorbance at a wavelength of 366 nm by utilizing the fact that it exists as CrO ₄ ²⁻ in an alkaline solution.

2. Chromium catalyst A2
The ethylene-based polymerization catalyst of the present invention may further contain a chromium catalyst A2 in addition to the chromium catalyst A1. The chromium catalyst A2 is formed by supporting a chromium compound C2 on amorphous inorganic oxide particles B2.
The chromium catalyst A2 is a chromium catalyst in which at least a part of chromium atoms is hexavalent, and is classified into a catalyst generally called a Phillips catalyst.
Kazuo Matsuura, Naotaka Mikami, "Polyethylene Technology Handbook," p. 81, 2001 Industrial Research Committee, M.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.I. B. Welch et al. "Handbook of Polyolefins Synthesis and Properties" p. 21 (1993) Marcel Dekker et al. Give an overview of this catalyst.
The chromium catalyst A2 is generally produced by bringing a chromium compound E, which will be described later, into contact with the amorphous inorganic oxide particles B2 (inorganic oxide carrier) and activating them in a non-reducing atmosphere.

(1) Inorganic oxide particles B2
In the chromium catalyst A2, amorphous inorganic oxide particles B2 are used as a carrier.
The inorganic oxide particles B2 include silica (SiO ₂ ) as a main component, silica-titania (SiO ₂ —TiO ₂ ) as a main component, and silica-alumina (SiO ₂ —Al ₂ O ₃ ) as a main component. It is preferable to be composed of at least one kind of particles selected from the group consisting of Here, the main component means a substance having a content rate (% by weight) of 90% by weight or more.
The content of silica (SiO ₂ ) in the particles containing silica (SiO ₂ ) as a main component may be 90% by weight or more, preferably 95% by weight or more, and more preferably 98% by weight or more. Of course, the content of silica (SiO ₂ ) may be 100% by weight.
The total content of silica (SiO ₂ ) and titania (TiO ₂ ) in the particles whose main component is silica-titania (SiO ₂ —TiO ₂ ) may be 90 wt% or more, but 95 wt% or more is preferable, More preferably, it is 98% by weight or more. Of course, the total content of silica (SiO ₂ ) and titania (TiO ₂ ) may be 100% by weight.
The total content of silica (SiO ₂ ) and alumina (Al ₂ O ₃ ) in the particles whose main component is silica-alumina (SiO ₂ —Al ₂ O ₃ ) is 90% by weight or more, but 95% by weight. The above is preferable, and 98% by weight or more is further preferable. Of course, the total content of silica (SiO ₂ ) and alumina (Al ₂ O ₃ ) may be 100% by weight.
Among these, it is preferable that the main component of the inorganic oxide particles B2 is particles of silica (SiO ₂ ) from the viewpoint of easy control of the particle shape of the inorganic oxide and catalytic performance.
When particles having silica-titania (SiO ₂ —TiO ₂ ) as a main component are used, titanium atom is 0.2 wt% to 10 wt%, preferably 0.5 wt% to 7 wt% as a metal component. %, More preferably 1 wt% to 5 wt% particles are used.
When particles of silica-zirconia (SiO ₂ —ZrO ₂ ) are used as the main component, zirconium atom is 0.2 wt% to 10 wt%, preferably 0.5 wt% to 7 wt% as the metal component. %, More preferably 1 wt% to 5 wt% particles are used.
When particles of silica-alumina (SiO ₂ —Al ₂ O ₃ ) are used as the main component, aluminum atom is 0.2 wt% to 10 wt%, preferably 0.5 wt% to be the metal component. 7% by weight, more preferably 1% to 5% by weight of particles are used.

The surface area of the inorganic oxide particles B2 is not particularly limited. From the viewpoint of supporting chromium atoms in a dispersed state, the surface area is preferably 100 m ² / g or more and 1000 m ² / g or less, more preferably 150 m ² / g or more and 950 m ² / g or less, and 200 m More preferably, it is ² / g or more and 900 m ² / g or less.

  The pore volume of the inorganic oxide particles B2 is not particularly limited. It is preferable that the pore volume is 0.3 mL / g or more and 5.0 mL / g or less from the viewpoint that the chromium atoms are supported in a dispersed state, and the polymer easily grows while the particles disintegrate during polymerization. It is more preferably 0.5 mL / g or more and 3.0 mL / g, and further preferably 0.7 mL / g or more and 2.5 mL / g or less.

(2) Average Particle Diameter of Chromium Catalyst A2 Particles The average particle diameter of the chromium catalyst A2 particles is not particularly limited. From the viewpoint of handling, the average particle diameter is preferably 0.001 μm or more and 200 μm or less, more preferably 0.005 μm or more and 150 μm or less, and further preferably 0.01 μm or more and 100 μm or less.
The average particle diameter of the particles of the chromium catalyst A2 is measured by a laser diffraction method or by measuring the particle diameters of 20 chromium catalysts A2 with a scanning electron microscope (SEM) and averaging the measured values. Desired. This time, for particles with an average particle size of 0.1 μm or more, the average particle size was determined by a particle size distribution measuring device using a laser diffraction method, and for particles with an average particle size of less than 0.1 μm, the average particle size was determined by SEM observation. It was

(3) Chromium compound C2
The chromium compound C2 is not particularly limited as long as it is a chromium compound in which at least some chromium atoms are hexavalent. For example, the chromium compound C2 is chromium oxide, chromium halide, oxyhalide, chromate, dichromate, nitrate, carboxylate, sulfate, chromium-1,3-diketo compound, chromate ester, etc. (Hereinafter, the trivalent chromium compounds such as chromium oxide to chromate ester listed here are also referred to as "chromium compound E"). After being supported by the inorganic oxide particles B2, the chromium compound E is activated in the non-reducing atmosphere to become the chromium compound C2. The hexavalent chromium compound C2 may be directly supported on the inorganic oxide particles B2.
As the chromium compound E, more specifically, chromium (III) oxide, chromium trichloride, chromyl chloride, potassium chromate, ammonium chromate, potassium dichromate, chromium nitrate, chromium sulfate, chromium acetate, tris (2- Examples include ethylhexanoate) chromium, chromium acetylacetonate, and bis (tert-butyl) chromate. Particularly, as the chromium compound E, chromium (III) oxide, chromium acetate, and chromium acetylacetonate are preferable.
Even when a chromium compound having an organic group such as chromium acetate or chromium acetylacetonate is used, the organic group portion is burned by activation in a non-reducing atmosphere described later, and finally chromium oxide ( It is known that, as in the case of using III), it reacts with the hydroxyl groups on the surface of the inorganic oxide carrier, and at least some of the chromium atoms become hexavalent and are immobilized in the structure of chromate ester ( V. J. Ruddic et al .; J. Phys. Chem. Vol. 100 p. 11062 (1996), SM Augustin et al .; J. Catal. Vol. 161 p. 641 (1996)).
The chromium compound C1 and the chromium compound C2 may be the same or different.
Further, the chromium compound D and the chromium compound E may be the same or different.

(4) Content of Chromium Atom in Chromium Catalyst A2 The content of chromium atom in the chromium catalyst A2 is not particularly limited. The content of chromium atoms is preferably 0.01% by weight to 2.0% by weight from the viewpoint that the supported chromium atoms do not aggregate with each other and are efficiently activated. The content is more preferably 0.1% by weight to 2.0% by weight, further preferably 0.2% by weight to 1.5% by weight.

(5) Supporting Chromium Compound E on Inorganic Oxide Particles B2 In order to support the above chromium compound E on the inorganic oxide particles B2, the following method can be adopted. Suitable examples include a method of impregnating the inorganic oxide particles B2 with a chromium compound E solution and then distilling off the solvent, and a method of sublimating the chromium compound E without using the solvent. Also, other known methods can be adopted. The supporting method is appropriately selected depending on the type of the chromium compound E used.
Further, when the inorganic oxide particles B2 are manufactured, the raw material to which the chromium compound E is added in advance may be used to directly obtain the inorganic oxide particles B2 carrying the chromium compound E.

(6) Activation The inorganic oxide particles B2 carrying the chromium compound E are fired in an activation furnace for activation. The activation is performed in a non-reducing atmosphere that does not substantially contain water. For example, it is performed under oxygen or air, but an inert gas may coexist. Preferably, it is carried out in a fluidized state by using molecular sieves or the like in circulation and sufficiently dried air.
The activation temperature is not particularly limited. The activation temperature is preferably 350 ° C to 900 ° C, more preferably 400 ° C to 850 ° C. The time for activation is not particularly limited. The time for activation is preferably 30 minutes to 48 hours, more preferably 1 hour to 35 hours, still more preferably 2 hours to 30 hours. By activation, at least a part of the chromium atoms of the chromium compound E supported on the inorganic oxide particles B2 is oxidized to be hexavalent, and as described above, the chromium compound C2 is chemically fixed on the inorganic oxide particles B2. To be done.
When the ethylene-based polymerization catalyst contains the chromium catalyst A1 and the chromium catalyst A2, the chromium catalyst A1 and the chromium catalyst A2 may be activated at the same time. That is, a mixture of the inorganic oxide particles B1 carrying the chromium compound D and the inorganic oxide particles B2 carrying the chromium compound E may be prepared in advance, and this mixture may be activated.

When supporting or activating the chromium compound E, a fluorine compound such as ammonium silicofluoride or ammonium hydrogen difluoride, titanium alkoxides such as titanium tetraisopropoxide, zirconium alkoxides such as zirconium tetrabutoxide, and aluminum trioxide. Aluminum alkoxides such as butoxide, organoaluminums exemplified by trialkylaluminums, metal alkoxides represented by organomagnesiums exemplified by dialkylmagnesium, or organometallic compounds are added to obtain ethylene polymerization activity or You may use together the well-known method which adjusts the molecular weight and molecular weight distribution of the obtained ethylene polymer.
In these metal alkoxides or organometallic compounds, by activation in a non-reducing atmosphere, the organic group portion is burned, oxidized to a metal oxide such as titania, zirconia, alumina or magnesia, and contained in the catalyst. . Further, the fluorine compound fluorinates the inorganic oxide carrier by thermally decomposing at the time of activation.
These methods are described in C.I. E. Marsden; Plastics, Rubber and Composites Processing and Applications Vol. 21 p. 193 (1994), T.W. Pullukat et al. J .; Polym. Sci. , Polym. Chem. Ed. Vol. 82 p. 118 (1980), M.A. P. McDaniel et al. J .; Catal. Vol. 82 p. 118 (1983), etc., for the outline or details.

The activation temperature and time are adjusted so that the chromium atoms contained in the chromium catalyst A2 are normally oxidized to 50 to 100% by weight, preferably 60 to 100% by weight, by activation.
The total amount of chromium atoms can be usually measured by a general metal analysis method such as plasma emission analysis or fluorescent X-ray method. Although the valence of chromium can be roughly estimated by observing the color change of a solid product (generally, hexavalent is yellow to orange, trivalent is green, and divalent is blue) by visual observation. The chelate titration method and the absorptiometry method are known as simple methods for quantitative determination. Specifically, the Chemical Society of Japan "Experimental Chemistry Course 15 Analysis" Maruzen (1991) P. 246-248. For example, in the case of trivalent chromium, an excess concentration of EDTA (ethylenediaminetetraacetic acid) of known concentration is added to trivalent chromium in an acidic solution, and the mixture is boiled for 5 to 10 minutes. It can be quantified by titrating. In the case of hexavalent chromium, it can be quantified by measuring the absorbance at a wavelength of 366 nm by utilizing the fact that it exists as CrO ₄ ²⁻ in an alkaline solution.

3. Characteristics of ethylene-based polymerization catalyst (1) Mixing ratio of chromium catalysts A1 and A2 in ethylene-based polymerization catalyst containing chromium catalysts A1 and A2 When the ethylene-based polymerization catalyst contains chromium catalyst A1 and chromium catalyst A2, chromium The mixing ratio of the catalyst A1 and the chromium catalyst A2 is not particularly limited. The mixing ratio by weight of the chromium catalyst A1 and the chromium catalyst A2 is preferably 1:99 to 99: 1, more preferably 5:95 to 95: 5, and more preferably 10:90 to 90:10. Is more preferable.
When the ethylene-based polymerization catalyst contains the chromium catalyst A1 and the chromium catalyst A2, the inorganic oxide particles B1 and the inorganic oxide particles B2 are mixed in advance and then granulated to obtain the inorganic oxide particles B3. Alternatively, the chromium compound C1 may be supported on this to form the chromium catalyst A3. In this case, in the produced chromium catalyst A3, the chromium compound C1 is carried on the inorganic oxide particles B1 and the chromium compound C1 is carried on the inorganic oxide particles B2. The catalyst A3 is composed of bonded particles in which particles of the chromium catalyst A1 and particles of the chromium catalyst A2 are bonded.
That is, in this ethylene-based polymerization catalyst (chromium catalyst A3), the chromium compound C1 is supported on the inorganic oxide particles B3 formed by granulating the plate-like inorganic oxide particles B1 and the amorphous inorganic oxide particles B2. It will be done.
This ethylene-based polymerization catalyst (chromium catalyst A3) granulates plate-like inorganic oxide particles B1 and amorphous inorganic oxide particles B2 into inorganic oxide particles B3, and the inorganic oxide particles B3 contain chromium. It can be produced by a production method which carries the compound C1.

  As a method for granulating the inorganic oxide particles B3, a known granulation method can be used, and examples thereof include a stirring granulation method, a spray granulation method, a tumbling granulation method, and a fluidized granulation method. . Among these, the spray granulation method is preferable from the viewpoint of easily maintaining the properties of the particles before mixing.

  In the case of spray granulation, an organic solvent such as water, methanol, ethanol, chloroform, methylene chloride, pentane, hexane, heptane, toluene, xylene can be used as a dispersion medium of the raw material slurry. Water is preferred.

  Further, a known binder such as an organic substance, an inorganic solvent, an inorganic salt or the like may be used during granulation.

In the case of spray granulation, the concentration of inorganic oxide particles (total of B1 and B2) in the raw material slurry is 0.1 to 70% by weight, preferably 1 to 50% by weight. The inlet temperature of the hot air for spray granulation varies depending on the dispersion medium, but when water is taken as an example, the temperature is 80 to 260 ° C, preferably 100 to 220 ° C. The mixing ratio of the plate-like inorganic oxide particles B1 and the amorphous inorganic oxide particles B2 is preferably 1:99 to 99: 1 by weight, and 5:95 to 95: 5. More preferably, it is more preferably 10:90 to 90:10.
The surface area of the chromium catalyst A3 is not particularly limited, usually, not more than ^{10 m} 2 / g or more 1000 m ² / g, preferably not more than ^{20 m} 2 / g or more ^{950m 2 / g, 50m 2 /} g or more 900 meters ² / G or less is more preferable.
The pore volume of the chromium catalyst A3 is not particularly limited, but normally the pore volume is 0.05 or more and 5.0 mL / g or less, preferably 0.1 or more and 3.0 mL / g or less, and More preferably, it is not less than 1 and not more than 2.5 mL / g.
The average particle size of the particles of the chromium catalyst A3 is not particularly limited, but from the viewpoint of handling, the average particle size is preferably 0.1 μm or more and 200 μm or less, and more preferably 0.2 μm or more and 150 μm or less. It is more preferably 0.5 μm or more and 100 μm or less.

(2) Content of chromium atom in ethylene-based polymerization catalyst The content of chromium atom in the ethylene-based polymerization catalyst is not particularly limited. The content of chromium atoms is preferably 0.01% by weight to 2.0% by weight from the viewpoint that the chromium atoms to be carried do not aggregate with each other and are efficiently activated. It is more preferably 0.1% by weight to 2.0% by weight, further preferably 0.2% by weight to 1.5% by weight.

(3) Components other than the chromium catalysts A1 and A2 in the ethylene-based polymerization catalyst The ethylene-based polymerization catalyst may contain components other than the chromium catalysts A1 and A2 as long as the effects of the present invention are not impaired. Good.
Other components are not particularly limited. The content (wt%) of other components is preferably 5 wt% or less.

4. Method for producing ethylene-based polymer In the method for producing an ethylene-based polymer of the present invention, a monomer containing at least ethylene is polymerized using the above-mentioned ethylene-based polymerization catalyst.

(1) Polymerization method The method for producing the ethylene polymer of the present invention can be carried out by a liquid phase polymerization method such as slurry polymerization or solution polymerization, or a gas phase polymerization method.
The liquid phase polymerization method is usually carried out in a hydrocarbon solvent. As the hydrocarbon solvent, a simple substance or a mixture of inert hydrocarbons such as propane, n-butane, isobutane, n-pentane, isopentane, hexane, heptane, octane, decane, cyclohexane, benzene, toluene and xylene is used.
Further, in the gas phase polymerization method, a commonly known polymerization method such as a fluidized bed or a stirred bed can be adopted in the presence of an inert gas. In the vapor phase polymerization method, a so-called condensing mode in which a medium for removing the heat of polymerization coexists can be adopted depending on the case.
As the polymerization method, not only single-stage polymerization in which an ethylene-based polymer is produced by using one reactor, but also multi-stage polymerization can be performed by connecting at least two reactors. In the case of multi-stage polymerization, a two-stage polymerization in which two reactors are connected and the reaction mixture obtained by polymerization in the first-stage reactor is continuously fed to the second-stage reactor is preferable. Transfer from the first-stage reactor to the second-stage reactor is performed through a connecting pipe. This transfer is preferably carried out by utilizing the differential pressure due to continuous discharge of the polymerization reaction mixture from the second stage reactor.

Next, the obtained ethylene polymer is preferably kneaded. The kneading can be performed using a single-screw or twin-screw extruder or a continuous kneader. Then, the obtained ethylene polymer can be molded by blow molding or the like by a conventional method.
In the present invention, when two kinds of different chromium catalysts, namely, the chromium catalyst A1 and the chromium catalyst A2 are mixed to produce an ethylene polymer, the mixing of the catalysts means the following methods (a) to (d). Any method can be used.
(A) A polymerization reaction is carried out in the presence or absence of a solvent or in the presence or absence of an organometallic compound in advance by mixing two types of catalysts, activating them in an activation furnace, and then extracting the mixed catalysts. How to introduce into the vessel.
(B) The two types of catalysts are individually activated in an activation furnace, and the extracted catalysts are mixed in advance in the presence or absence of a solvent or in the presence or absence of an organometallic compound. To the polymerization reactor.
(C) The two types of catalysts are individually activated in an activation furnace, and the extracted catalysts are separately separated in advance in the presence or absence of a solvent or in the presence or absence of an organometallic compound. Method of introducing into polymerization reactor and further mixing in one polymerization reactor (d) Inorganic oxide particles B1 and inorganic oxide particles B2 are mixed in advance, and then granulated to form inorganic oxide particles B3 (mixed As a carrier), a chromium compound (chromium compound D or chromium compound E) is supported, activated in an activation furnace, and the extracted mixed catalyst is previously present in the presence or absence of a solvent or in the presence of an organometallic compound. Alternatively, the method of introducing it into the polymerization reactor in the absence thereof.

(2) Polymerization conditions 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, and further preferably It is 70 ° C to 150 ° C.
The catalyst concentration and ethylene concentration in the reactor may be any concentration as long as it is a concentration sufficient to allow the polymerization to proceed. For example, the catalyst concentration can range from about 0.0001 wt% to about 5 wt% based on the weight of the reactor contents in the case of liquid phase polymerization. Similarly, in the case of gas phase polymerization, the ethylene concentration can be in the range of 0.1 MPa to 10 MPa as the total pressure.
If necessary, hydrogen can be introduced into the polymerization reactor to adjust the molecular weight.

(3) Copolymerization In the method for producing an ethylene polymer of the present invention, in addition to ethylene homopolymerization, propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, Α-Olefin such as 1-octene may be used alone or in combination of two or more kinds in a polymerization reactor for copolymerization.
The α-olefin content in the obtained ethylene-based copolymer is 15 mol% or less, preferably 10 mol% or less.

(4) Organometallic compound In the polymerization, for the purpose of finely adjusting the molecular weight or molecular weight distribution of the ethylene polymer, or for the purpose of removing impurities in the polymerization system as a scavenger, an organometallic compound is introduced as a cocatalyst, It can also be contacted with an ethylene-based polymerization catalyst.
In particular, the organometallic compound has an effect of improving catalytic activity and an effect of making hydrogen as a molecular weight modifier more effective with respect to the ethylene-based polymerization catalyst.
As the organometallic compound, organometallic compounds of Groups 1, 2 and 13 of the periodic table, specifically, organolithium compounds, organomagnesium compounds, organoaluminum compounds and organoboron compounds are preferably used. Furthermore, organic aluminum compounds and organic boron compounds are preferable.

Examples of the organolithium compound include alkyllithium, specifically, methyllithium, n-butyllithium and the like.
Examples of the organic magnesium compound include dialkyl magnesium, specifically butylethyl magnesium and dibutyl magnesium.
Examples of the organic aluminum compound include trialkylaluminum and dialkylaluminum alkoxide, specifically, trimethylaluminum, triethylaluminum, triisobutylaluminum and diethylaluminum ethoxide.
Examples of the organic boron compound include trialkylborane, specifically, triethylborane.
The amount of the organometallic compound to be contacted is preferably such that the molar ratio of metal atom to chromium atom is 0.2 to 1000, preferably 0.5 to 100.

5. Effects of this Embodiment According to the ethylene-based polymerization catalyst and the method for producing an ethylene-based polymer of this embodiment, it is possible to design an HDPE material (high-density polyethylene material) having an excellent balance between durability and fluidity.

  Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited by these Examples unless departing from the gist thereof.

1. Physical Property Measuring Methods Physical property measuring methods and the like used in Examples and Comparative Examples are as follows.
(1) Average value of plate thickness T of particles of chromium catalyst A1: The plate thickness T (nm) of 10 particles of chromium catalyst A1 is measured by a scanning electron microscope (SEM), and the measured values are averaged. I asked for it.
(2) Average value of D / T: It was determined by observing 10 particles of the chromium catalyst A1 with a scanning electron microscope (SEM). That is, the average value of D / T uses 10 particles of the chromium catalyst A1, and for each particle, D / T, which is the ratio of the maximum particle diameter D (nm) to the plate thickness T (nm), is calculated. It was calculated and calculated by averaging the values.
(3) Powder X-ray diffraction (XRD): Powder X-ray diffraction was measured by the following device and conditions.
Device: Rigaku X-ray Diffractometer Smartlab
X-ray source: Cu-Kα ray (using Kβ absorption plate), tube voltage 40 kV, tube current 30 mA
Optical system: Focusing method Divergence slit 2/3 degrees, scattering slit 2/3 degrees, light receiving slit 0.300mm
Scan mode: 2θ / θ scan 2θ scan range: 3.0000 to 55.0000 degree Angle step width: 0.0200 degree Scan speed: 4.0000 degree / min Detector: Scintillation counter (4) Surface area and pore volume Silica After each sample was heated and sufficiently dried under reduced pressure, the adsorption isotherm of nitrogen was measured at a liquid temperature by using Autosorb 3B type manufactured by Canterchrome. The pore volume was calculated from the adsorption amount of the obtained adsorption isotherm at a relative pressure of 0.95, and the BET multipoint analysis was performed to calculate the specific surface area. Furthermore, assuming that the pore structure is a cylinder, the average pore diameter was calculated according to the formula (1). In this formula, D _ave represents the average pore diameter, V _total represents the pore volume, and S _BET represents the specific surface area by the BET multipoint method.
D _ave = 4V _total / S _BET formula (1)
Further, the mesopore distribution was obtained by BJH method analysis, and the pore volume in the specified range was calculated.
(5) HLMI: Based on ASTM-D-1238-57T, it measured at 190 degreeC and a 21.6 kg load.
(6) Content of hexavalent chromium: An aqueous solution of NaOH (0.1M) was added to the catalyst component to dissolve the hexavalent chromium, and a part of the solution was taken and quantified by measuring the absorbance at a wavelength of 366 nm. .
(7) Average particle size: Measured using a laser diffraction / scattering particle size distribution measuring device LA-920 manufactured by Horiba, Ltd. in a dispersion solvent under the conditions of ethanol, a refractive index of 1.0 and a shape coefficient of 1.0, and a median. The value of the diameter was used as the average particle diameter.

2. Examples and Comparative Examples (1) Example 1
(1.1) Preparation of Chromium Catalyst 1 After impregnating inorganic oxide particles 1 (plate-like silica aggregate (planar silica aggregate), "Sun Lovely" (manufactured by Asahi Glass SITEC Co., Ltd.)) into a chromium acetate aqueous solution. Then, water was distilled off to obtain chromium-containing silica having a chromium content of 0.5% by weight. Then, the chromium-containing silica was activated in a dry air atmosphere at 600 ° C. for 20 hours to obtain a chromium catalyst 1 (Phillips type catalyst). Upon activation, the chromium-containing silica changed color from light blue to light orange. From this, it can be seen that the chromium atom was converted to hexavalent. In the trivalent chromium, substantially 99% by weight was converted to hexavalent.
The structural analysis data of the inorganic oxide particles 1 are as follows.

<Structural analysis data of inorganic oxide particles 1>
XRD: peak at 2θ = 25.8 °, full width at half maximum 1.5 °
BET method: surface area 84 m ² / g
Pore volume: 0.2 mL / g
SiO ₂ purity: 99.5% (weight basis)
Ratio of maximum diameter to plate thickness (D / T): The ratio of the diameter to the plate thickness average value (20 nm) observed in the SEM image was 50 or more in all cases.

(1.2) Physical Properties of Chromium Catalyst 1 The peak position of XRD of the chromium catalyst 1 is between the plate-like silica aggregate B1 (raw material) dried at 200 ° C. and the chromium catalyst 1 supporting chromium acetate and activated at 600 ° C. , Hardly changed. This means that the tabular silica aggregate B1 has good thermal stability.
The SEM image of the chromium catalyst 1 is shown in FIG. It can be seen from FIG. 2 that the chromium catalyst 1 has a plate-like particle shape.

(1.3) Ethylene Polymerization 198 mg of chromium catalyst 1 and 800 mL of isobutane were introduced into a 2.0 L polymerization tank which was sufficiently replaced with nitrogen, and the internal temperature was raised to 100 ° C.
Then, ethylene was injected under pressure, and polymerization was carried out at a polymerization temperature of 100 ° C. for 2 hours while keeping the ethylene partial pressure at 1.4 MPa. Then, the content gas was released to the outside of the system to terminate the polymerization. As a result, 27 g of an ethylene-based polymer was obtained. In the HLMI of the obtained ethylene polymer, the polymer did not flow. Therefore, it is determined to be less than 0.01 g / 10 minutes. The density was 0.9518 g / cm ³ .

(2) Example 2
(2.1.1) Preparation of chromium catalyst 1 Prepared in the same manner as in Example 1.
(2.1.2) Preparation of Chromium Catalyst 2 The inorganic oxide particles 2 (amorphous silica aggregate) were impregnated with an aqueous solution of chromium acetate, and then water was distilled off to obtain a chromium content of 1.0% by weight. A silica containing chromium was obtained. Then, the chromium-containing silica was activated in a dry air atmosphere at 820 ° C. for 18 hours to obtain a chromium catalyst 2 (Phillips type catalyst). Upon activation, the chromium-containing silica changed color from light blue to light orange. From this, it can be seen that the chromium atom was converted to hexavalent. In the trivalent chromium, substantially 99% by weight was converted to hexavalent.
The structural analysis data of the amorphous silica aggregate B2 is as follows.

<Structural analysis data of inorganic oxide particles 2>
XRD: Broad peak peculiar to amorphous near 2θ = 22 ° BET method: Surface area 310 m ² / g
Pore volume: 1.7 mL / g
SiO ₂ purity: 99.8% (weight basis)

(2.2) Ethylene Polymerization 198 mg of chromium catalyst 1 and 52 mg of chromium catalyst 2 of 800 ml of isobutane were introduced into a 2.0-liter polymerization tank sufficiently replaced with nitrogen, and the internal temperature was raised to 100 ° C.
Then, ethylene was injected under pressure, and polymerization was carried out at a polymerization temperature of 100 ° C. for 130 minutes while maintaining the ethylene partial pressure at 1.4 MPa. Then, the content gas was released to the outside of the system to terminate the polymerization. As a result, 267 g of an ethylene-based polymer was obtained. The HLMI of the obtained ethylene polymer was 5.0 g / 10 minutes, and the density was 0.9579 g / cm ³ .

(3) Comparative Example 1
(3.1) Preparation of chromium catalyst 2 It was prepared in the same manner as in Example 2.
The structural analysis data of the inorganic oxide particles 2 are as described in the above section “Preparation of (2.1.2) Chromium catalyst 2”.

(3.2) Ethylene Polymerization 38 mg of chromium catalyst 2 and 800 mL of isobutane were introduced into a 2.0 L polymerization tank sufficiently replaced with nitrogen, and the internal temperature was raised to 100 ° C.
Next, ethylene was injected under pressure, and polymerization was carried out at a polymerization temperature of 100 ° C. for 120 minutes while maintaining the ethylene partial pressure at 1.4 MPa. Then, the content gas was released to the outside of the system to terminate the polymerization. As a result, 201 g of an ethylene-based polymer was obtained. The HLMI of the obtained ethylene polymer was 10.0 g / 10 minutes, and the density was 0.9580 g / cm ³ .

(4) Example 3
(4.1) Preparation of Chromium Catalyst 3 Inorganic oxide particles 2-2 (amorphous silica aggregate, 40 g, average particle size 12 μm) and inorganic oxide particles 1 used in Example 1 (Sunlabry, 120 g, The average particle size of 4.3 μm) was slurried in 340 mL of distilled water. This slurry was spray-dried and granulated with the above-mentioned inorganic oxide particles / water slurry under the following conditions using a spray-drying granulator (Okawara Kakohki “L-8”).
Atomizer type: M type rotary disc atomizer rotation speed: 10,000 rpm
Slurry supply rate: 1.0 L / h
Entrance temperature: 150 ℃
As a result of granulation, inorganic oxide particles 3 having an average particle size of 39.6 μm were recovered from under the main body.
The obtained inorganic oxide particles 3 were impregnated with an aqueous solution of chromium acetate, and then water was distilled off to obtain chromium-containing silica having a chromium content of 0.5% by weight. Then, the chromium-containing silica was activated under a dry air atmosphere at 730 ° C. for 12 hours to obtain a chromium catalyst 3 (Phillips type catalyst). Upon activation, the chromium-containing silica changed color from light blue to light orange. From this, it can be seen that the chromium atom was converted to hexavalent. In the trivalent chromium, substantially 99% by weight was converted to hexavalent.

<Structural analysis data of inorganic oxide particles 2-2>
XRD: Broad peak peculiar to amorphous near 2θ = 22 ° BET method: Surface area 320 m ² / g
Pore volume: 1.6 mL / g
SiO ₂ purity: 99.8% (weight basis)
Average particle size: 12 μm

(4.2) Ethylene Polymerization 130 mg of the chromium catalyst 3 obtained in Example 4.1 and 800 mL of isobutane were introduced into a 2.0 L polymerization tank sufficiently replaced with nitrogen, and the internal temperature was raised to 100 ° C. .
Then, ethylene was injected under pressure, and polymerization was carried out at a polymerization temperature of 100 ° C. for 200 minutes while maintaining the ethylene partial pressure at 1.4 MPa. Then, the content gas was released to the outside of the system to terminate the polymerization. As a result, 330 g of an ethylene polymer was obtained. The HLMI of the obtained ethylene polymer was 0.9 g / 10 minutes, and the density was 0.9521 g / cm ³ .

(5) Comparative example 2
(5.1) Preparation of Chromium Catalyst 4 The inorganic oxide particles 2-2 (amorphous silica aggregate, 100 g, average particle size 12 μm) of Example 3 were slurried in 400 mL of distilled water. Using a spray drying granulator (Okawara Kakohki Co., Ltd. “L-8”), this slurry was treated in the same manner as in Example 3 (4.1), and the inorganic oxide particles 2 having an average particle diameter of 99.2 μm 2 2 granules were obtained.
The obtained inorganic oxide particles 2-2 granules were impregnated with an aqueous solution of chromium acetate, and then water was distilled off to obtain chromium-containing silica having a chromium content of 0.5% by weight. Then, the chromium-containing silica was activated in a dry air atmosphere at 730 ° C. for 12 hours to obtain a chromium catalyst 4 (Phillips type catalyst). Upon activation, the chromium-containing silica changed color from light blue to light orange. From this, it can be seen that the chromium atom was converted to hexavalent. In the trivalent chromium, substantially 99% by weight was converted to hexavalent.

(5.2) Ethylene polymerization 62 mg of the chromium catalyst 4 obtained in Comparative Example 2 (5.1) and 800 mL of isobutane were introduced into a 2.0 L polymerization tank which was sufficiently replaced with nitrogen, and the internal temperature was raised to 100 ° C. The temperature was raised.
Next, ethylene was injected under pressure to carry out polymerization at a polymerization temperature of 100 ° C. for 70 minutes while maintaining the ethylene partial pressure at 1.4 MPa. Then, the content gas was released to the outside of the system to terminate the polymerization. As a result, 197 g of an ethylene-based polymer was obtained. The HLMI of the obtained ethylene polymer was 2.3 g / 10 minutes, and the density was 0.9560 g / cm ³ .

3. Discussion of Results of Examples and Comparative Examples Table 1 shows the results of Examples and Comparative Examples. In Table 1, the description in the column "presence or absence of crystalline particles" has the following meanings. Further, the polymer density in Table 1 is a value rounded off to the fourth decimal place.
The description of "presence or absence of crystalline particles" in Table 1 indicates that in the powder X-ray diffraction of the inorganic oxide particles before containing the chromium compound, the half value width is 0.2 ° or more and 5 ° or less at 2θ = 23 ° to 29 °. In the case where it has a peak showing the crystallinity of, it is defined as “present”. As described in “(1.2) Physical properties of chromium catalyst 1” in Example 1, no change was observed in the powder X-ray analysis after the addition of the chromium compound and after the addition of the chromium compound. For the evaluation of "presence or absence of particles", the result of powder X-ray diffraction of inorganic oxide particles was used. Since Example 1 is the chromium catalyst 1 including the inorganic oxide particles 1, it was “present”.
Comparative Example 1 was "absent" because it was a chromium catalyst 2 made of inorganic oxide particles 2.

From the comparison between Example 1 and Comparative Example 1, it can be seen that an ethylene polymer having a high molecular weight can be obtained by using the plate-shaped chromium catalyst 1 using the plate-shaped silica aggregate. Further, by comparing Example 2 and Comparative Example 1, by mixing the chromium catalyst 1 and the chromium catalyst 2 for use in the polymerization, the ethylene catalyst having a higher molecular weight than the ethylene polymer obtained by the chromium catalyst 2 alone is used. It can be seen that coalescence is obtained. Further, by comparing Example 3 with Comparative Example 2, a carrier obtained by mixing and granulating the inorganic oxide particles 1 which are tabular silica aggregates and the inorganic oxide particles 2 which are amorphous silica aggregates was used. It can be seen that also in the chromium catalyst 3, an ethylene-based polymer having a higher molecular weight can be obtained as compared with the case where the carrier granulated with the inorganic oxide particles 2-2, which is an amorphous silica aggregate, alone is used.
From the above results, it was confirmed that an ethylene polymer having an ultrahigh molecular weight component can be produced by using an ethylene polymerization catalyst containing a chromium catalyst having a plate-like particle shape. This is preferred for blown materials.

  The present invention is not limited to the embodiments described in detail above, and various modifications and changes can be made within the scope of the claims of the present invention.

  According to the present invention, an ethylene polymer having an ultrahigh molecular weight component can be produced. Since this ethylene-based polymer can be applied to a wide range of uses, it is industrially very useful.

Claims (24)

An ethylene-based polymerization catalyst containing a chromium catalyst A1,
The chromium catalyst A1 is an ethylene-based polymerization catalyst characterized in that the inorganic oxide particles B1 carry the chromium compound C1 and the particle shape is plate-like. The ethylene-based polymerization catalyst according to claim 1, wherein the inorganic oxide particles B1 are particles whose main component is SiO ₂ .   The average value of the plate thickness T (nm) of the particles of the chromium catalyst A1 is 1 nm or more and 100 nm or less, and the ethylene-based polymerization catalyst according to claim 1 or 2.   The ethylene system according to claim 3, wherein an average value of D / T, which is a ratio between the maximum diameter D (nm) of the particles of the chromium catalyst A1 and the plate thickness T (nm), is 10 or more. Polymerization catalyst.   The ethylene according to any one of claims 1 to 4, which has a peak showing crystallinity in a half width of 0.2 ° or more and 5 ° or less at 2θ = 23 ° to 29 ° in powder X-ray diffraction. System polymerization catalyst.   Content of chromium atom is 0.01 weight% -2.0 weight%, The ethylene-type polymerization catalyst of any one of Claims 1-5 characterized by the above-mentioned.   The ethylene-based polymerization catalyst according to any one of claims 1 to 6, further comprising a chromium catalyst A2 in which a chromium compound C2 is supported on amorphous inorganic oxide particles B2. The inorganic oxide particles B2 are at least one selected from the group consisting of particles containing SiO ₂ as a main component, particles containing SiO ₂ —TiO ₂ as a main component, and particles containing SiO ₂ —Al ₂ O _{3 as} a main component. The ethylene-based polymerization catalyst according to claim 7, which is composed of the above particles.   The ethylene-based polymerization catalyst according to claim 7 or 8, wherein the mixing ratio of the chromium catalyst A1 and the chromium catalyst A2 is 1:99 to 99: 1 by weight. The content of chromium atoms contained in the chromium catalyst A1 is 0.01% by weight to 2.0% by weight, and the content of chromium atoms contained in the chromium catalyst A2 is 0.01% by weight to 2%. It is 0.0 weight%, The ethylene-type polymerization catalyst of any one of Claims 7-9 characterized by the above-mentioned.   The ethylene-based polymerization catalyst according to any one of claims 7 to 10, wherein the particles of the chromium catalyst A1 and the particles of the chromium catalyst A2 are combined to form combined particles.   A method for producing an ethylene-based polymer, which comprises polymerizing a monomer containing at least ethylene with the ethylene-based polymerization catalyst according to claim 1. An ethylene-based polymerization catalyst containing a chromium catalyst A1,
An ethylene-based polymerization catalyst, wherein the chromium catalyst A1 contains agglomerated particles obtained by aggregating a structure in which a chromium compound C1 is supported on plate-like inorganic oxide particles B1. The ethylene-based polymerization catalyst according to claim 13, wherein the inorganic oxide particles B1 are particles whose main component is SiO ₂ .   The ethylene-based polymerization catalyst according to claim 13 or 14, wherein an average value of the plate thickness T (nm) of the particles of the chromium catalyst A1 is 1 nm or more and 100 nm or less.   The ethylene system according to claim 15, wherein an average value of D / T, which is a ratio between the maximum diameter D (nm) of the particles of the chromium catalyst A1 and the plate thickness T (nm), is 10 or more. Polymerization catalyst.   The ethylene according to any one of claims 13 to 16, which has a peak showing crystallinity in a half width of 0.2 ° or more and 5 ° or less at 2θ = 23 ° to 29 ° in powder X-ray diffraction. System polymerization catalyst.   Content of a chromium atom is 0.01 weight% -2.0 weight%, The ethylene-type polymerization catalyst of any one of Claims 13-17 characterized by the above-mentioned.   The ethylene-based polymerization catalyst according to any one of claims 13 to 18, further comprising a chromium catalyst A2 in which a chromium compound C2 is supported on amorphous inorganic oxide particles B2. The inorganic oxide particles B2 are at least one selected from the group consisting of particles containing SiO ₂ as a main component, particles containing SiO ₂ —TiO ₂ as a main component, and particles containing SiO ₂ —Al ₂ O _{3 as} a main component. 20. The ethylene-based polymerization catalyst according to claim 19, comprising the above particles.   The ethylene-based polymerization catalyst according to claim 19 or 20, wherein a mixing ratio of the chromium catalyst A1 and the chromium catalyst A2 is 1:99 to 99: 1 by weight. The content of chromium atoms contained in the chromium catalyst A1 is 0.01% by weight to 2.0% by weight, and the content of chromium atoms contained in the chromium catalyst A2 is 0.01% by weight to 2%. It is 0.0 weight%, The ethylene-type polymerization catalyst of any one of Claims 19-21.   23. The ethylene-based polymerization catalyst according to claim 19, wherein particles of the chromium catalyst A1 and particles of the chromium catalyst A2 are bonded to each other to form bonded particles.   A method for producing an ethylene-based polymer, which comprises polymerizing a monomer containing at least ethylene using the ethylene-based polymerization catalyst according to any one of claims 13 to 23.