JP2006241257A - Method for polymerizing olefin - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for polymerizing an olefin by which a polyolefin with excellently balanced ESCR (environmental stress cracking resistance) and impact resistance is produced by using an easily producible catalyst made to exhibit industrially sufficient activity, and by which the molecular weight of the produced polyolefin can be easily controlled. <P>SOLUTION: This method for polymerizing an olefin comprises polymerizing the olefin in the existence of a polymerization catalyst obtained by combining a chromium oxide catalyst (A) carried on a silica-titania carrier and activated by firing under a nonreducing atmosphere with an organoaluminum compound (B) expressed by general formula (1): R<SP>1</SP><SB>(3-n)</SB>-Al-L<SB>n</SB>, wherein R<SP>1</SP>is a 2-12C alkyl group; L is a 1-8C alkoxy group or a phenoxy group; and n is a real number larger than 0 but smaller than 1. <P>COPYRIGHT: (C)2006,JPO&amp;NCIPI

Description

  The present invention relates to an olefin polymerization method, and more particularly to an olefin polymerization method using a catalyst comprising a specific organoaluminum compound and a chromium oxide catalyst supported on a silica-titania support. The present invention relates to the production of a polyolefin having an excellent balance between environmental stress crack resistance and impact strength.

Conventionally, as a catalyst for olefin polymerization, a chromium catalyst in which at least a part of chromium atoms become hexavalent by supporting a chromium compound on an inorganic oxide carrier and activating the firing in a non-reducing atmosphere is generally Philips. It is known as a catalyst for olefin polymerization called as a catalyst (see, for example, Non-Patent Document 1). Further, it is known that by using a silica-titania carrier as a carrier, the activity is improved, and the molecular weight of the produced polyolefin is lowered (for example, see Non-Patent Document 2). It is also known that by using a silica-titania support, an ethylene-based copolymer suitable for large blows having an excellent balance between environmental stress crack resistance (ESCR) and impact strength can be efficiently produced ( For example, Patent Document 1). In addition, in the polymerization of olefins, it is already known to use an organoaluminum compound as a chromium-based catalyst (see, for example, Patent Documents 2 and 3). In these documents, regarding the hydrocarbon group contained in the organoaluminum compound, for example, Patent Document 1 broadly defines that a hydrocarbon group having 1 to 14 carbon atoms is desirable. However, the polymerization activity is improved by using these organoaluminum compounds, but industrially sufficient activity is not necessarily expressed. In addition, when ethylene is polymerized using these organoaluminum compounds, low molecular weight 1-alkenes and low molecular weight alkanes such as 1-hexene, which is a by-product ethylene trimer, are generated. However, it has been a problem not only to reduce the production efficiency of the polymer but also to lower the physical properties such as density and impact strength of the produced polymer, and it has been very difficult to solve this problem.
Patent Document 4 discloses that, in the polymerization of olefins, a specific organoaluminum compound is used as a chromium-based catalyst, thereby having industrially sufficient activity, low molecular weight 1-alkenes and low molecular weight alkanes. It has been disclosed that olefins can be efficiently polymerized by suppressing the formation of olefins, and the molecular weight of the polyolefins produced can be easily suppressed. However, this catalyst is also insufficient from the viewpoint of the balance between environmental stress crack resistance (ESCR) and impact strength.

  In addition, when these catalysts are used, hydrogen that is generally used as a molecular weight regulator in olefin polymerization using a general Ziegler catalyst is difficult to use because it significantly reduces the polymerization activity. . For this reason, in the production of a polymer using a catalyst in which this transition metal compound is supported on a refractory compound carrier, there is no method for controlling the molecular weight of the produced polymer other than the polymerization temperature, and this newly affects the catalyst activity. Development of a method for controlling the molecular weight that does not affect it has been desired. In the polymerization of polyolefin using a silylchromate catalyst, a technique for controlling the molecular weight of a polyolefin produced by using an organoaluminum compound in combination is already known. For example, Patent Document 5 discloses the technique. However, in this document, there has been no description of a chromium oxide catalyst supported on a refractory compound and activated by firing in a non-reducing atmosphere. In Patent Document 5, it is widely defined that a hydrocarbon group having 1 to 14 carbon atoms is desirable. All organoaluminum compounds included in this description are supported on a refractory compound and are not reduced. When combined with a chrome oxide catalyst activated by calcination in an atmosphere, industrially sufficient activity was not necessarily expressed.

M.M. P. McDaniel, Advances in Catalysis, 33, 47 (1985) M.M. P. McDaniel, M.M. B. Welch, J .; Catal. , 82, 98 (1983) JP 2002-138105 A Japanese Patent Publication No. 47-023176 Japanese Patent Publication No. 03-023564 JP 2000-086718 A Japanese Patent Publication No. 44-002996

  The present invention produces a polyolefin having industrially sufficient activity and excellent balance between ESCR and impact strength by using a catalyst that can be easily produced, and easily controlling the molecular weight of the produced polyolefin. This is the issue.

As a result of intensive investigations in view of the above problems, the present inventors have achieved high activity by combining a chromium oxide catalyst supported on a silica-titania support and activated by firing in a non-reducing atmosphere with a specific organoaluminum compound. It has been found that polyolefins having an excellent balance between ESCR and impact strength can be produced, and that molecular weight adjustment with hydrogen is easy. That is, the present invention combines a chromium oxide catalyst (A) supported on a silica-titania support and fired and activated in a non-reducing atmosphere, and an organoaluminum compound (B) represented by the following general formula (1). A method for polymerizing an olefin in the presence of a polymerization catalyst.
R ¹ _(3-n) -Al-L _n (1)
(Wherein R ¹ is an alkyl group having 2 to 12 carbon atoms, L is an alkoxy group or phenoxy group having 1 to 8 carbon atoms, and n is a real number greater than 0 and less than 1)
Further, the molecular weight of the polyolefin to be produced is controlled by changing the value of the real number n in the general formula (1) in the range of 0.5 or more and less than 1. Polymerization method.
Moreover, by changing the value of the real number n in the general formula (1) in a range of 0.5 or more and less than 1, the environmental stress crack resistance and impact strength of the produced polyolefin are controlled. The method for polymerizing olefins as described above.

  According to the present invention, by using a catalyst that can be easily produced, it has industrially sufficient activity, efficiently inhibits the formation of low molecular weight 1-alkenes and low molecular weight alkanes, and efficiently polymerizes olefins. The molecular weight of the polyolefin can be easily controlled.

The present invention will be specifically described below.
In order to describe the present invention in detail, silica-titania supports carrying chromium compounds in the present invention are known and disclosed in, for example, US Pat. No. 3,887,494. The specific surface area is preferably 50 m ² or more 1000 m ² or less as measured by the BET method of the carrier, more preferably 200 meters ² or more 800 m ² or less. If it is less than 50 m ² , the activity of the chromium oxide catalyst may not be sufficient, which is not preferable. If it is more than 1000 m ² , the strength of the support may decrease, which is not preferable. The pore volume adopting the adsorption amount of P / P ₀ and Max in the BET method of this support is preferably 0.5 cm ³ / g or more and 3.0 cm ³ / g or less, and 1.0 cm ³ / g or more. more preferably 3.0cm at ³ / g or less, and further preferably 1.5 cm ³ / g or more 3.0cm ³ / g or less. If the pore volume is less than 0.5 cm ³ / g, the polymerizability of α-olefin such as 1-butene or 1-hexene of the chromium oxide catalyst may be lowered, which is not preferable, and is larger than 3.0 cm ³ / g. In such a case, the strength of the carrier may decrease, which is not preferable. The average particle size of the carrier measured by a laser particle size distribution analyzer is preferably 5 μm or more and 200 μm or less, and more preferably 10 μm or more and 150 μm or less. If the average particle size is less than 5 μm, it is not preferable because it may interfere with stable olefin polymerization by adhering in the polymerization vessel or in the piping, and if it is larger than 200 μm, the generated polyolefin particles are too large and transported. This is not preferable because it may cause trouble.

This silica-titania carrier can be prepared by, for example, coprecipitation of silicate and a water-soluble titanium salt during silica gel formation, or TiX ₄ , Ti (OR ² ) ₄ (X is a halogen atom, R ² is a carbonized carbon having a substituent. It can be prepared by a method of impregnating a hydrogen group and the like and performing a heat treatment. Moreover, a commercial item can also be obtained and used. It is also possible to prepare a catalyst in which a chromium compound is supported on silica in advance, and react this with Ti (OR ² ) ₄ or the like. The titanium content in the silica-titania support is preferably 0.5% by weight or more and 10% by weight or less, more preferably 1.0% by weight or more and 8.0% by weight or less as titanium atoms. If the titanium content is less than 0.5% by weight, the characteristics of the silica-titania support are not sufficient, and the balance between ESCR and impact strength may be inferior, and this is not preferable. If it exceeds 10% by weight, the polymerization activity may decrease. Is not preferable.

Next, the chromium oxide catalyst (A) used in the present invention will be described.
The chromium oxide catalyst (A) used in the present invention comprises a chromium compound such as chromium oxide, halide, oxyhalide, phosphate, sulfate, oxalate, alcoholate, organic compound, etc. It can be easily prepared by supporting these carriers by various methods such as impregnation, distillation, sublimation and the like, followed by calcination. Preferred chromium compounds include chromium (VI) oxide, chromium (III) acetate, chromium (III) nitrate, chromium (III) acetoneate, chromium (III) sulfate, chromium (III) chloride, chromyl chloride, potassium chromate, Ammonium chromate, potassium dichromate, tris (2-ethylhexanoate) chromium, chromium acetylacetonate, bis (1,1-dimethylethyl) chromate, butylchromate, etc., among others, chromium oxide (VI), Particularly preferred are chromium (III) nitrate, chromium (III) acetate, and chromium acetylacetonate. The amount of the chromium compound to be supported is 10% by weight or less, preferably 0.1 to 5% by weight based on the weight of the chromium atom relative to the support.

By specific surface area measured by the BET method of chromium oxide catalyst (A) used in the present invention is preferably 50 m ² / g or more 1000 m ² / g or less, 200m ² / g or more 800 m ² / g or less is more preferred. If it is less than 50 m ² / g, the activity of the chromium oxide catalyst may not be sufficient, which is not preferable. If it is greater than 1000 m ² / g, the strength of the chromium oxide catalyst may decrease, which is not preferable. Preferably P / P _0, Max pore volume employing the adsorption amount of or less 0.5 cm ³ / g or more 3.0 cm ³ / g in the BET method of oxidation chromium catalyst, 1.0 cm ³ / More preferably, it is g or more and 3.0 cm ³ / g or less. When the pore volume is less than 0.5 cm ³ / g, the polymerizability of α-olefin such as 1-butene and 1-hexene of the chromium oxide catalyst may be lowered, which is not preferable, and is more than 3.0 cm ³ / g. If it is large, the strength of the chromium oxide catalyst may decrease, which is not preferable. The average particle size of the carrier measured by a laser particle size distribution analyzer is preferably 5 μm or more and 200 μm or less, and more preferably 10 μm or more and 150 μm or less. If the average particle size is less than 5 μm, the chromium oxide catalyst is not preferable because it may interfere with the stable polymerization of olefins by adhering in the polymerization vessel or in the piping. Is too large, which may hinder transportation.

The chromium oxide catalyst (A) used in the present invention is fired and activated in a non-reducing atmosphere.
The non-reducing atmosphere is, for example, an oxygen atmosphere or an air atmosphere that substantially does not contain moisture. In this non-reducing atmosphere, an inert gas such as nitrogen or argon may coexist. For example, it is preferable to use air that has been sufficiently dried by circulating in a desiccant such as molecular sieves.
This calcination activation is to oxidize at least a part of the chromium compound supported by heating the chromium oxide catalyst (A) to hexavalent and chemically fix it on the support. In order to uniformly and uniformly activate the chromium oxide catalyst (A), it is preferable to perform the activation in a fluid state. The firing temperature is preferably 300 ° C. or higher and 1100 ° C. or lower, and more preferably 400 ° C. or higher and 1000 ° C. or lower. If the temperature is lower than 300 ° C., the ratio of the chromium compound oxidized to hexavalent is reduced, so that the olefin polymerization activity of the chromium oxide catalyst (A) may decrease. Since the specific surface area decreases due to sintering, the olefin polymerization activity of the chromium oxide catalyst (A) may decrease, which is not preferable. The firing time is preferably 5 minutes or longer and 30 hours or shorter, more preferably 1 hour or longer and 10 hours or shorter. If it is less than 5 minutes, the ratio of the chromium compound oxidized to hexavalent is low, so that the olefin polymerization activity of the chromium oxide catalyst (A) may be lowered. This is not preferable because the production efficiency of the chromium catalyst (A) is deteriorated.

Next, the organoaluminum compound (B) will be described.
This organoaluminum compound (B) is an organoaluminum compound represented by the general formula (1).
R ¹ _(3-n) -Al-L _n (1)
(Wherein R ¹ is an alkyl group having 2 to 12 carbon atoms, L is an alkoxy group or phenoxy group having 1 to 8 carbon atoms, and n is a real number greater than 0 and less than 1)
In this organoaluminum compound (B), the molar ratio of the alkoxy group or phenoxy group to the aluminum atom is more than 0 and less than 1, preferably 0.5 or more and less than 1, more preferably 0.8 or more and less than 1. It is.

  Moreover, the carbon number contained in the alkyl group which this organoaluminum compound (B) has is 2 or more and 12 or less, preferably 6 or more and 10 or less. Examples of the alkyl group include ethyl, propyl, 1-methylethyl, butyl, 1-methylpropyl, 2-methylpropyl, 1,1-dimethylethyl, pentyl, 1-methylbutyl, 2-methylbutyl, 3-methylbutyl, 1,1-dimethylpropyl, 1,2-dimethylpropyl, 2,2-dimethylpropyl, hexyl, heptyl, octyl, 1-methylheptyl, 2-methylheptyl, 3-methylheptyl, 4-methylheptyl, 5-methyl Heptyl, 6-methylheptyl, 1-ethylhexyl, 2-ethylhexyl, 3-ethylhexyl, 4-ethylhexyl, 1-propylpentyl, 2-propylpentyl, nonyl, 1-methyloctyl, 2-methyloctyl, 3-methyloctyl, 4-methyloctyl, 5-methyloctyl, 6 Examples include methyloctyl, 7-methyloctyl, 1-ethylheptyl, 2-ethylheptyl, 3-ethylheptyl, 4-ethylheptyl, 5-ethylheptyl, 1-propylhexyl, 2-propylhexyl, 3-propylhexyl and the like. It is done.

  The organoaluminum compound (B) has an alkoxy group having 1 to 8 carbon atoms. Examples of the alkoxy group include methoxy, ethoxy, propoxy, 1-methylethoxy, butoxy, 1-methylpropoxy, 1 , 1-dimethylethoxy, pentoxy, hexoxy, heptoxy, octoxy, 2-ethylhexoxy group and the like. The organoaluminum compound (B) has a phenoxy group having 6 to 20 carbon atoms. Examples of the alkoxy group include phenoxy, crezzoxy, thymoxy, carbacoxy, 2,5-bis (1,1 -Dimethylethyl) -4-methylphenoxy, naphthoxy, anthoxy and the like.

Such an organoaluminum compound (B) can be easily produced by reacting aluminum trialkyls with alcohols or phenols by a known method. For example, a method of adding alcohols or phenols to aluminum trialkyls, a method of adding aluminum trialkyls to alcohols or phenols, and simultaneously introducing aluminum trialkyls and alcohols or phenols into a reactor It can be manufactured by a method or the like. It is also possible to introduce these compounds directly into the polymerization system for reaction. Further, an organoaluminum compound having a molar ratio of alkoxy group or phenoxy group to aluminum atom of 1 or more, such as aluminum octyl diethoxide, and an organoaluminum compound having a low ratio of alkoxy group or phenoxy group to aluminum atom, such as aluminum trioctyl. , And may be mixed and reacted to synthesize this organoaluminum compound (B).
In the polymerization of olefins, this organoaluminum compound (B) may be used alone or in combination of two or more.

The combination of the chromium oxide catalyst (A) and the organoaluminum compound (B), that is, the method of using the catalyst of the present invention is not particularly limited, but it is preferable to supply both components separately in the polymerization reactor. The ratio of both components is usually 0.01 or more and 100 or less, preferably 0.1 or more and 50 or less in terms of Al / Cr molar ratio. If it is less than 0.01, the chromium oxide catalyst (A) and the organoaluminum compound (B) cannot react sufficiently, which may reduce the olefin polymerization activity of the chromium oxide catalyst (A). If it is larger than 100, the reaction between the chromium oxide catalyst (A) and the organoaluminum compound (B) proceeds excessively, which may reduce the olefin polymerization activity, which is not preferable.
In the polymerization method of the present invention, the molecular weight of the produced polyolefin can be controlled by the real number n of the following general formula (1) representing the organoaluminum compound (B). That is, as n increases, the molecular weight of the polyolefin produced decreases.
R ¹ _(3-n) -Al-L _n (1)
(Wherein R ¹ is an alkyl group having 2 to 12 carbon atoms, L is an alkoxy group or phenoxy group having 1 to 8 carbon atoms, and n is a real number greater than 0 and less than 1)
At this time, the range of the real number n is 0.5 or more and less than 1, preferably 0.7 or more and less than 1, and more preferably 0.8 or more and less than 1.

In the polymerization method of the present invention, the ESCR (environmental stress crack resistance) and impact strength of the polyolefin to be produced can be controlled by the real number n of the following general formula (1) representing the organoaluminum compound (B). . That is, as n increases, the ESCR gradually decreases and the impact strength increases gradually.
R ¹ _(3-n) -Al-L _n (1)
(Wherein R ¹ is an alkyl group having 2 to 12 carbon atoms, L is an alkoxy group or phenoxy group having 1 to 8 carbon atoms, and n is a real number greater than 0 and less than 1)
At this time, the range of the real number n is 0.5 or more and less than 1, preferably 0.7 or more and less than 1, and more preferably 0.8 or more and less than 1.
In the olefin polymerization using the catalyst of the present invention, the molecular weight of the produced polyolefin can be adjusted by hydrogen. At this time, the ratio of the hydrogen partial pressure to the pressure in the polymerization reactor is 0% or more and less than 70%, preferably 0% or more and less than 50%, and more preferably 0% or more and less than 30%.

The olefin that can be polymerized using the catalyst of the present invention is a 1-olefin, and ethylene is particularly preferable. Furthermore, the catalyst of the present invention is a copolymer of ethylene and a monoolefin such as propylene, 1-butene, 1-hexene, 1-octene, or 1,3-butadiene, isoprene, 1,5-hexadiene, 1,7 -It can also be used for polymerization in the presence of a diene such as octadiene.
As the polymerization method, usual suspension polymerization, solution polymerization, and gas phase polymerization are possible. In the case of suspension polymerization or solution polymerization, the catalyst is a polymerization solvent, for example, aliphatic hydrocarbons such as propane, butane, pentane, hexane and heptane, aromatic hydrocarbons such as benzene, toluene and xylene, and fats such as cyclohexane and methylcyclohexane. It can introduce | transduce into a reactor with a cyclic hydrocarbon, can inject ethylene into 0.1-20 Mpa in inert atmosphere, and can superpose | polymerize at the temperature of room temperature or more and 320 degrees C or less. On the other hand, in the gas phase polymerization, ethylene is mixed by fluidized bed, moving bed or stirring so that the contact between ethylene and the catalyst is good under a temperature condition of room temperature to 120 ° C. at a pressure of 1 to 50 kg / cm 2. It is possible to carry out the polymerization by taking the following means.

The present invention will be described in detail with reference to examples and comparative examples, but the present invention is not limited to the following examples unless it exceeds the gist. FIG. 1 is a flowchart for helping understanding of the technical contents included in the present invention, and the present invention is not restricted by the flowchart unless departing from the gist of the present invention.
Hydrogen, hexane and isobutane used in Examples and Comparative Examples were dehydrated using MS-13X (manufactured by Showa Union), and hexane and isobutane were used after deoxygenation by performing vacuum degassing using a vacuum pump. did. Ethylene, hexane, and 1-hexene used in Examples and Comparative Examples were dehydrated using MS-3A (manufactured by Showa Union), and hexane and 1-hexene were further degassed by vacuum degassing using a vacuum pump. Used after oxygen. The specific surface area and pore volume of the support and catalyst in the examples were measured with an autosorb 3MP apparatus manufactured by Yuasa Ionics, using nitrogen as an adsorbed gas. The BET method was used for the surface area, the BJH method was used for the pore diameter and pore distribution, and the adsorption amount was P / P ₀ , Max for the pore volume. The average particle size of the carrier and catalyst in the examples was measured using SALD-2100 manufactured by Shimadzu Corporation.

  The catalyst activity in the examples represents 1 g of catalyst component (A) and the amount of polymer produced per hour (g). The melt index (HMI) of the polymer is a value measured at a temperature of 190 ° C. and a load of 21.6 kg in accordance with JIS K7120. The density in the examples was measured by the density gradient tube method of JIS K7112. The Charpy impact strength in the examples is a value measured according to JIS K7111. The measurement was performed by adjusting the temperature at −25 ° C. for 24 hours after inserting a test piece notch. The b-ESCR in the examples is one of the indicators of environmental stress crack resistance, and was measured according to JIS-K6760. As a test solution, a 10% by weight aqueous solution of Antalox (C0630) manufactured by Lion Co., Ltd. was used, and the time at which the probability of cracking due to environmental stress was 50% was measured to obtain the value of b-ESCR.

[Example 1]
EP50 (manufactured by INEOS SILICAS Ltd.) was used as a silica-titania carrier. The specific surface area was 500 m ² / g, the pore volume was 2.3 cm ³ / g, and the average particle size was 120 μm. This EP50 contained 2.6% by weight of titania as Ti. 4 mmol of chromium (III) acetate was dissolved in 80 ml of distilled water, 20 g of EP50 was immersed in this solution, stirred at room temperature for 1 hour, and then the slurry was heated to distill off the water. After drying under reduced pressure at 10 ° C. for 10 hours, the mixture was baked by circulating dry air at 800 ° C. for 5 hours to obtain a catalyst component (A) containing 1.0% by weight of chromium.
On the other hand, as the catalyst component (B), an organoaluminum compound obtained by reacting methanol and aluminum trioctyl at a molar ratio of 0.9: 1 was used.
0.4 mmol of the catalyst component (B) and 0.8 liter of hexane were placed in an autoclave having an internal volume of 1.5 liter, the inside of which was vacuum degassed and purged with nitrogen. Then 3 ml of 1-hexene was added. Next, the inside of the autoclave was kept at 80 ° C., 0.03 MPa of hydrogen was added, and ethylene was added to make the total pressure 1.0 MPa. Thereafter, 20 mg of the catalyst component (A) was added to initiate polymerization. Polymerization was performed for 1 hour while maintaining the total pressure at 1.0 MPa by supplying ethylene. Table 1 shows the yield, catalytic activity, HMI, density, Charpy impact strength and b-ESCR of the polymer obtained by this polymerization.

[Comparative Example 1]
Ethylene was polymerized in the same manner as in Example 1 except that EP10 (manufactured by INEOS SILICAS Ltd.), which is a silica carrier, was used as the carrier for the catalyst component (A) and 5 ml of 1-hexene was added. The specific surface area of EP10 was 330 m ² / g, the pore volume was 1.8 cm ³ / g, and the average particle size was 100 μm. This EP10 did not contain titania. Table 1 shows the yield, catalytic activity, HMI, density, Charpy impact strength and b-ESCR of the polymer obtained by this polymerization.

[Example 2]
As the catalyst component (A), Magnapore 963T100 (manufactured by WR Grace) was used after calcination by passing dry air at 800 ° C. for 5 hours. The specific surface area of the catalyst component (A) was 460 m ² / g, the pore volume was 2.1 cm ³ / g, and the average particle size was 90 μm. This Magnapore963T100 contained 2.3% by weight of titania as Ti.
On the other hand, as the catalyst component (B), an organoaluminum compound obtained by reacting methanol and aluminum trioctyl at a molar ratio of 0.9: 1 was used.
The polymerization was performed in a polymerization vessel having a volume of 230 L in a single-stage polymerization process. The polymerization temperature was 77 ° C. and the polymerization pressure was 2.4 MPa. The catalyst component (A) was supplied to the polymerization vessel at a rate of about 3.6 g / hr so that the concentration of the catalyst component (B) in the polymerization vessel was adjusted to 0.10 mmol / liter. Isobutane is supplied at a rate of 30 L / hr, ethylene is supplied at a rate of 10 kg / hr, hydrogen is supplied as a molecular weight regulator so that the gas phase concentration is about 5.4 mol%, and 1-hexene is added at a rate of 0.1. Polymerization was carried out by feeding at a rate of 4 L / h. Table 2 shows the catalytic activity obtained by this polymerization, the HMI, density, Charpy impact strength and b-ESCR of the obtained polymer.

[Example 3]
As the catalyst component (A), EP352 (manufactured by INEOS SILICAS Ltd.) was used after calcination by flowing dry air at 600 ° C. for 5 hours. The specific surface area of the catalyst component (A) was 490 m ² / g, the pore volume was 1.1 cm ³ / g, and the average particle size was 70 μm. This EP352 contained 2.6% by weight of titania as Ti.
On the other hand, as the catalyst component (B), an organoaluminum compound obtained by reacting methanol and aluminum trioctyl at a molar ratio of 0.9: 1 was used.
The polymerization was performed in a polymerization vessel having a volume of 230 L in a single-stage polymerization process. The polymerization temperature was 75 ° C. and the polymerization pressure was 2.4 MPa. The catalyst component (A) was supplied to the polymerization vessel at a rate of about 4.5 g / hr so that the concentration of the catalyst component (B) in the polymerization vessel was adjusted to 0.10 mmol / liter. Isobutane is supplied at a rate of 30 L / h, ethylene is supplied at a rate of 10 kg / hr, and hydrogen is supplied as a molecular weight regulator so that the gas phase concentration is about 5.4 mol%. Polymerization was carried out by feeding at a rate of 2 L / h. Table 2 shows the catalytic activity obtained by this polymerization, the HMI, density, Charpy impact strength and b-ESCR of the obtained polymer.

[Comparative Example 2]
As a catalyst component (A), ES370X (manufactured by INEOS SILICAS Ltd.) was used after being calcined by flowing dry air at 800 ° C. for 5 hours. The specific surface area of the catalyst component (A) was 320 m ² / g, the pore volume was 1.45 cm ³ / g, and the average particle size was 50 μm. This ES370X did not contain titania.
On the other hand, as the catalyst component (B), an organoaluminum compound obtained by reacting methanol and aluminum trioctyl at a molar ratio of 0.9: 1 was used.
The polymerization was performed in a polymerization vessel having a volume of 230 L in a single-stage polymerization process. The polymerization temperature was 87 ° C. and the polymerization pressure was 2.4 MPa. The catalyst component (A) was fed to the polymerization vessel at a rate of about 7.5 g / hr so that the concentration of the catalyst component (B) in the polymerization vessel was 0.10 mmol / liter. Isobutane was supplied at a rate of 30 L / hr, ethylene was supplied at a rate of 10 kg / hr, and hydrogen was supplied as a molecular weight regulator so that the gas phase concentration was about 1.0 mol%. Polymerization was carried out by feeding at a rate of 4 L / h. Table 2 shows the catalytic activity obtained by this polymerization, the HMI, density, Charpy impact strength and b-ESCR of the obtained polymer.

[Comparative Example 3]
As catalyst component B, ethylene polymerization was carried out in the same manner as in Example 1 except that an organoaluminum compound obtained by reacting ethanol and aluminum triethyl at a molar ratio of 1: 1 was used. Table 2 shows the catalytic activity obtained by this polymerization, the HMI, density, Charpy impact strength and b-ESCR of the obtained polymer.

[Example 4]
The polymerization of ethylene was carried out in the same manner as in Example 1 except that an organoaluminum compound prepared by reacting ethanol and aluminum trioctyl at a molar ratio of 0.5: 1 was used as the catalyst component (B). Table 3 shows the yield of the polymer obtained by this polymerization, catalytic activity, and HMI of the obtained polymer.
[Example 5]
The polymerization of ethylene was carried out in the same manner as in Example 1 except that an organoaluminum compound prepared by reacting ethanol and aluminum trioctyl at a molar ratio of 0.7: 1 was used as the catalyst component (B). Table 3 shows the yield of the polymer obtained by this polymerization, catalytic activity, and HMI of the obtained polymer.

[Example 6]
The polymerization of ethylene was carried out in the same manner as in Example 1 except that an organoaluminum compound prepared by reacting ethanol and aluminum trioctyl at a molar ratio of 0.85: 1 was used as the catalyst component (B). Table 3 shows the yield of the polymer obtained by this polymerization, catalytic activity, and HMI of the obtained polymer.
[Example 7]
The polymerization of ethylene was carried out in the same manner as in Example 1 except that an organoaluminum compound prepared by reacting ethanol and aluminum trioctyl at a molar ratio of 0.95: 1 was used as the catalyst component (B). Table 3 shows the yield of the polymer obtained by this polymerization, catalytic activity, and HMI of the obtained polymer.

[Example 8]
Example 1 except that an organoaluminum compound prepared by reacting ethanol and aluminum trioctyl at a molar ratio of 0.5: 1 was used as the catalyst component (B) and 0.3 MPa of hydrogen was added during the polymerization. In the same manner, ethylene was polymerized. Table 4 shows the HMI, density, Charpy impact strength, and b-ESCR of the polymer obtained by this polymerization.
[Example 9]
Example 1 except that an organoaluminum compound prepared by reacting ethanol and aluminum trioctyl in a molar ratio of 0.95: 1 was used as the catalyst component (B) and 0.02 MPa of hydrogen was added during the polymerization. In the same manner, ethylene was polymerized. Table 4 shows the HMI, density, Charpy impact strength, and b-ESCR of the polymer obtained by this polymerization.

As shown in Table 1 and Table 2, the polymerization carried out in Examples has sufficient polymerization activity by comparing Example 1, Comparative Example 1, and Examples 2, 3, and Comparative Examples 2, 3. It is clear that the resulting polyolefin has an excellent balance between impact strength and b-ESCR. Moreover, as shown in Table 3, it is clear that the molecular weight of the polyolefin produced can be controlled by Examples 4 to 7 by the value of the real number n in the following general formula (1).
Further, as shown in Table 4, it is clear that Examples 8 and 9 can control the impact strength and ESCR of the polyolefin to be produced by the value of the real number n in the following general formula (1).
R ¹ _(3-n) -Al-L _n (1)
(Wherein R ¹ is an alkyl group having 2 to 12 carbon atoms, L is an alkoxy group or phenoxy group having 1 to 8 carbon atoms, and n is a real number greater than 0 and less than 1)

  The olefin polymerization catalyst and polymerization method of the present invention can be suitably used in the field of polyolefin production, particularly blow molding polyethylene.

It is a flowchart for helping understanding of the technology included in the present invention.

Claims (3)

Polymerization catalyst comprising a combination of a chromium oxide catalyst (A) supported on a silica-titania support and activated by firing in a non-reducing atmosphere, and an organoaluminum compound (B) represented by the following general formula (1) Of polymerizing olefins in the presence of water.
R ¹ _(3-n) -Al-L _n (1)
(Wherein R ¹ is an alkyl group having 2 to 12 carbon atoms, L is an alkoxy group or phenoxy group having 1 to 8 carbon atoms, and n is a real number greater than 0 and less than 1) The molecular weight of the polyolefin produced is controlled by changing the value of the real number n in the general formula (1) in the range of 0.5 or more and less than 1, Polymerization method. By changing the value of the real number n in the general formula (1) in a range of 0.5 or more and less than 1, the environmental stress crack resistance and impact strength of the polyolefin to be produced are controlled. Item 2. The method for polymerizing olefins according to Item 1.

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