JPS6312083B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing polyethylene, and more particularly to a method for efficiently producing polyethylene with a wide molecular weight distribution using a specific catalyst.

Generally, polyethylene is widely used as an excellent synthetic resin in various fields, but polyethylene with a wide molecular weight distribution is desired from the viewpoint of moldability and physical properties of molded products.

By the way, as a catalyst for producing polyethylene,
It is known that a magnesium compound supported by reacting a titanium halide has higher activity than a simple Ziegler catalyst. However, in conventional production methods, when trying to widen the molecular weight distribution of polyethylene, the catalyst activity decreases, resulting in a decrease in production efficiency and a large amount of catalyst, which requires a step to remove the catalyst from the polyethylene obtained. There were some drawbacks, such as not being able to move.

The present inventors have conducted extensive research to overcome the drawbacks of the above-mentioned conventional techniques and to develop a method for producing polyethylene with a wide molecular weight distribution using a highly active catalyst. As a result, the inventors discovered that the object could be achieved by using a solid product obtained by a specific treatment as a component of the catalyst, leading to the completion of the present invention.

That is, the present invention provides at least titanium, which is obtained by reacting (A) a magnesium compound, a silicon halide, an alcohol, and a titanium halide;
The general formula AlR ¹ _o X ¹ _3-o (wherein R ¹ is alkyl group,
X ¹ is a halogen atom, and n is 0<n<3
It is. Provided is a method for producing polyethylene, which comprises polymerizing ethylene using a solid product obtained by reacting an organic aluminum halide compound represented by (B) and a catalyst containing an organic aluminum compound as an active ingredient. It is something.

The catalyst used in the method of the present invention is prepared from the above components (A) and (B), among which
The compound containing at least titanium, magnesium and halogen, which is the base of the solid product which is component (A), is obtained by reacting a magnesium compound, silicon halide, alcohol and titanium halide. There are various types of magnesium compounds, including magnesium oxide, magnesium hydroxide, magnesium carbonate,
Examples include magnesium inorganic compounds such as magnesium sulfate and magnesium halides, and dialkoxymagnesiums such as magnesium diethoxide.

The solid product which is the component (A) in the catalyst used in the method of the present invention is prepared by the operation shown below.
First, a solid material obtained by the above-described treatment, that is, a compound containing at least titanium, magnesium, and halogen, is reacted with tetraalkoxyzirconium. Here, specific examples of the tetraalkoxyzirconium include tetramethoxyzirconium, tetraethoxyzirconium, tetrapropoxyzirconium, and tetrabutoxyzirconium, among which tetrabutoxyzirconium is particularly preferred. Further, in this reaction, a tetrahalogenated zirconium such as tetrachlorozirconium and/or a tetraalkoxytitanium such as tetraethoxytitanium or tetraisopropoxytitanium is added. When zirconium tetrahalide or tetraalkoxytitanium is added here, the polyethylene produced has a wider molecular weight distribution and has significantly improved various physical properties. There is no limit to the blending ratio of the compounds used in this case, and it may be selected appropriately depending on various conditions, but usually 1 mole of titanium atoms in the above-mentioned solid substance, that is, a compound containing at least titanium, magnesium, and halogen. In contrast, the amount of tetraalkoxyzirconium is set in the range of 0.1 to 20 mol, preferably 0.5 to 10 mol, and the amount of zirconium tetrahalide and tetraalkoxytitanium is set as appropriate in the range of 0 to 20 mol, preferably 0.05 to 10 mol. Other conditions for the above reaction include temperature 0
The temperature is set at ~200°C, preferably 30~150°C, and the reaction time is set at 5 minutes to 10 hours, preferably 30 minutes to 5 hours,
Also pentane, hexane, heptane, octane,
Preferably, an inert hydrocarbon such as cyclohexane, benzene or toluene is used as the solvent.

After thoroughly washing the solid content generated in the above reaction,
Further, this solid content is reacted with an organic aluminum halide compound represented by the general formula AlR ¹ _o X ¹ _3-o . Various types ^of organic aluminum halides can be considered as long as R ¹ , Preferred examples include aluminum monochloride, methylaluminum dichloride, ethylaluminum dichloride, isopropylaluminum dichloride, isobutylaluminum monochloride, and mixtures thereof. Here, the amount of organic aluminum halide is usually 1 to 200 mol, preferably 10 to 200 mol, per 1 mol of titanium atom in the solid content.
Defined in the range of ~100 moles. Also, this reaction is 0~
5 minutes to 10 hours at 200℃, preferably 30 to 150℃,
Preferably, it is carried out under conditions of 30 minutes to 5 hours, and pentane, hexane, heptane, octane,
Inert hydrocarbons such as cyclohexane, benzene, toluene can also be used as solvents,
Alternatively, the reaction may be carried out in the form of a slurry without a solvent.

In the method of the present invention, the solid product obtained by the above reaction is washed as necessary, and the solid product is used as the catalyst (A).
Use as an ingredient.

Next, various types of organoaluminum compounds can be considered as component (B) of the catalyst used in the method of the present invention, but they usually have the general formula AlR ² _n X ² _3-n (where R ²
is an alkyl group, X ² is a halogen atom, and m is 0<m≦3. ) or the general formula AlR ³ _k (OR ⁴ ) _3-k (wherein R ³ and R ⁴ represent an alkyl group, and k satisfies 0<k≦3).
The one expressed as is used. Specific examples of the organoaluminum compounds include trimethylaluminum, triethylaluminum, triisopropylaluminium, triisobutylaluminum, diethylaluminium monochloride, diisopropylaluminum monochloride, diisobutylaluminum monochloride, dioctylaluminum monochloride, ethylaluminum dichloride, Examples include diethylaluminum monoethoxide, isopropylaluminum dichloride, and ethylaluminum sesquichloride.

The method of the present invention is to produce polyethylene using a catalyst containing the above-mentioned components (A) and (B) as active ingredients. The mixing ratio of components (A) and (B) in this catalyst is not particularly limited, but usually the aluminum atom in component (B) is 1 to 1000 (mol) per 1 titanium atom in component (A). ratio), preferably 10 to 500 (molar ratio). In addition, the amount of the catalyst consisting of both components (A) and (B) to be used in the production of polyethylene is not particularly limited and may be determined according to various conditions, but it is usually 0.001 to 0.001 in terms of titanium atoms.
It should be 10 mmol/, preferably 0.005-0.5 mmol/.

When producing polyethylene by polymerizing ethylene by the method of the present invention, the above-mentioned
A catalyst prepared from components (A) and (B) is added, and then ethylene is introduced. The polymerization method and conditions are not particularly limited, and any of solution polymerization, suspension polymerization, gas phase polymerization, etc. is possible, and both continuous polymerization and discontinuous polymerization are possible. As the reaction medium, inert solvents such as butane, pentane, hexane, cyclohexane, heptane, benzene, toluene, etc. are preferred. Furthermore, the ethylene pressure in the reaction system is 2
~100Kg/cm ² , preferably 5 to 50Kg/cm ² , the reaction temperature is 20 to 200°C, preferably 50 to 150°C, and the reaction is carried out for 5 minutes to 10 hours, preferably 30 minutes to 5 hours. The desired polyethylene can then be obtained. The molecular weight during polymerization may be controlled by known means such as hydrogen.

The types of polyethylene that can be polymerized by the method of the present invention include not only ethylene homopolymers but also copolymers of ethylene and a small amount of α-olefin.

Since the method of the present invention uses the above-mentioned catalyst,
It has high catalytic activity, and a sufficient effect can be obtained even with a small amount of use, and as a result, the deashing step (catalyst removal step) can be omitted. Moreover, the polyethylene obtained has a large bulk specific gravity, a good particle size, a small amount of fine powder, and a wide molecular weight distribution.
Therefore, this polyethylene has very good moldability and excellent physical properties. In addition, the method of the present invention is an extremely effective method because the molecular weight distribution of the resulting polyethylene can be controlled within a desired range by appropriately selecting the catalyst compounding ratio, polymerization conditions, etc.

Next, examples of the present invention will be shown. In addition, in the following examples, all operations were performed under an argon stream. In addition, the evaluation of molecular weight distribution was performed at 190℃, 2.16
Kg load for melt index (MI _2.16 )
The melt flow ratio (FR) was the ratio of the melt index (MI _21.6 ) at a load of 21.6 kg.

Reference Example 1 (1) Production of a compound containing at least titanium, magnesium and halogen.

In a 500ml four-necked flask, add 150ml of dry n-hexane and 10.0g of magnesium diethoxide.
(88 mmol), silicon tetrachloride 3.7 g (22 mmol)
was added, and 2.0 g (33 mmol) of isopropyl alcohol was added dropwise over 1 hour while stirring at 20°C, followed by reaction under reflux for 2 hours. Next, 42 g (220 mmol) of titanium tetrachloride was added dropwise to this system, and the reaction was carried out under reflux for 3 hours while stirring. After the reaction was completed, the produced solid substance was washed with n-hexane to obtain the target compound containing titanium, magnesium, and halogen. Note that the titanium content in this compound was 5.8% by weight.

(2) Production of component (A) of the catalyst.

In a 200ml flask, add dry n-hexane.
50 ml of the compound obtained in (1) above was added as magnesium (8.8 mmol) (titanium: 1.2 mmol), and further 5 mmol of tetraptoxyzirconium was added, and the mixture was reacted at 70° C. for 2 hours with stirring. The system was then cooled to room temperature, allowed to stand, and the supernatant liquid was removed. The precipitate was washed once with 50 ml of n-hexane. Then, 2.2 mmol of ethylaluminum dichloride was added, and the reaction was carried out at 70°C for 2 hours. Summer. After cooling, the precipitate was washed five times with 50 ml of n-hexane to obtain a solid product, which is component (A) of the catalyst.

(3) Manufacture of polyethylene.

In a 1-volume stainless steel autoclave, 400 ml of dry n-hexane, 2.0 mmol of triisobutylaluminum, which is the (B) component of the catalyst, and the solid product, which is the (A) component of the catalyst obtained in (2) above, were added. Added 0.0025 mmol as titanium, 8℃
The temperature rose to . Hydrogen 2 is then added to this system as a partial pressure.
Kg/cm ² and 6 kg/cm ² of ethylene were introduced under pressure, and polymerization was carried out at 80° C. for 1 hour while continuously supplying ethylene to maintain this pressure. After the reaction was completed, unreacted gas was removed and the polymer was separated and dried to obtain 88.7 g of white polyethylene. Catalytic activity is per gram of titanium atom per hour.
It weighed 739Kg. The bulk density of the obtained polyethylene was 0.25 g/cm ³ , MI _2.16 was 0.31, and FR was 52.

Reference example 2 (1) Production of component (A) of the catalyst.

Into a 200 ml flask were added 8.8 mmol of the compound obtained in Reference Example 1 (1) as magnesium (1.2 mmol as titanium), 2.0 mmol of tetrabutoxyzirconium, and 50 ml of dry n-hexane, and the mixture was heated at 70°C with stirring. The mixture was allowed to react for 3 hours. Next, 26.4 mmol of ethylaluminum dichloride was added to this system, and the mixture was reacted at 70°C for 3 hours. After cooling, the precipitate was washed five times with 50 ml of n-hexane to obtain a solid product, which is component (A) of the catalyst.

(2) Manufacture of polyethylene.

In a 1-volume stainless steel autoclave, 400 ml of dry n-hexane, 2 mmol of triisobutylaluminum, which is the component (B) of the catalyst, and the solid product, which is the component (A) of the catalyst obtained in (1) above, were mixed with titanium. 0.01 mmol was added as a solution, and the temperature was raised to 80°C. Next, hydrogen was added to this system as a partial pressure of 3 kg/cm ² ,
5 kg/cm ² of ethylene was injected and heated to 80°C while continuously supplying ethylene to maintain this pressure.
Polymerization was carried out for 1 hour. After the reaction was completed, unreacted gas was removed and the polymer was separated and dried to obtain 92 g of white polyethylene. The bulk density of the obtained polyethylene was 0.25 g/cm ³ , MI _2.16 was 0.30,
FR was 65.

Example 1 (1) Production of component (A) of the catalyst.

In a 200 ml flask, add 8.8 mmol of the compound obtained in Reference Example 1 (1) as magnesium (1.2 mmol as titanium), 2.0 mmol of tetrabutoxyzirconium, and 2.0 mmol of zirconium tetrachloride.
mmol and 50 ml of dry n-hexane were added and reacted at 70° C. for 3 hours with stirring. Next, 44 mmol of ethylaluminum dichloride was added to this system, and the mixture was reacted at 70°C for 2 hours. After cooling, the mixture was allowed to stand and the supernatant liquid was removed, and the precipitate was washed five times with 50 ml of n-hexane to obtain a solid product, which is component (A) of the catalyst.

(2) Manufacture of polyethylene.

Ethylene polymerization was carried out under the same conditions as in Reference Example 2, except that the solid product obtained in (1) above was used as component (A) of the catalyst. The result is polyethylene 83
g is obtained, and the bulk density of this polyethylene is 0.25
g/cm ² , MI _2.16 was 0.13, and FR was 69.

Example 2 (1) Production of component (A) of the catalyst.

In a 200 ml flask, add 8.8 mmol of the compound obtained in Reference Example 1 (1) as magnesium (1.2 mmol as titanium), 2.0 mmol of tetrabutoxyzirconium, and tetrabutoxytitanium.
1.0 mmol and 50 ml of dry n-hexane were added and reacted at 70° C. for 3 hours with stirring. Next, 44 mmol of ethylaluminum dichloride was added to this system, and the mixture was reacted at 70°C for 2 hours. After cooling, let it stand, remove the supernatant liquid, and add the precipitate to n-hexane 50
A solid product, which is the component (A) of the catalyst, was obtained by washing with 5 mL of water.

(2) Manufacture of polyethylene.

Ethylene polymerization was carried out under the same conditions as in Reference Example 2, except that the solid product obtained in (1) above was used as component (A) of the catalyst. The result is polyethylene 66
g is obtained, and the bulk density of this polyethylene is 0.26
g/cm ² , MI _2.16 was 0.43, and FR was 60.

Example 3 (1) Production of component (A) of the catalyst.

In a 200 ml flask, add 8.8 mmol of the compound obtained in Reference Example 1 (1) as magnesium (1.2 mmol as titanium), 2.0 mmol of tetrabutoxyzirconium, and 2.0 mmol of zirconium tetrachloride.
1.0 mmol of tetrabutoxytitanium and 50 ml of dry n-hexane were added, and the mixture was reacted at 70° C. for 3 hours with stirring. Then 44 mmol of ethylaluminum dichloride was added to this system,
The reaction was carried out at 70°C for 2 hours. After cooling, the mixture was allowed to stand and the supernatant liquid was removed, and the precipitate was washed five times with 50 ml of n-hexane to obtain a solid product, which is component (A) of the catalyst.

(2) Manufacture of polyethylene.

Ethylene polymerization was carried out under the same conditions as in Reference Example 2, except that the solid product obtained in (1) above was used as component (A) of the catalyst. The result is polyethylene
79.5g was obtained, and the bulk density of this polyethylene was
0.25 g/cm ³ , MI _2.16 was 0.25, and FR was 63.

Comparative Example (1) Production of a compound containing at least titanium, magnesium and halogen.

In a 500ml flask, add dry n-hexane.
150 ml, magnesium diethoxide 10 g (88 mmol) and titanium tetrachloride 42 g (220 mmol)
was added and reacted under reflux for 3 hours. After the reaction was completed, the mixture was cooled, allowed to stand, and the supernatant liquid was removed, followed by sufficient washing with n-hexane to obtain a compound containing titanium, magnesium, and chlorine. The titanium content in this compound was 20.0% by weight.

(2) Manufacture of polyethylene.

In a 1-volume stainless steel autoclave, add 400 ml of dry n-hexane, 2.0 mmol of triisobutylaluminum as component (B) of the catalyst, and 0.0025 mmol of the compound obtained in (1) above as titanium, and raise the temperature to 80°C. did. Next, 2 kg/cm ² of hydrogen and 6 kg/cm ² of ethylene were pressurized into the system as partial pressures, and polymerization was carried out at 80° C. for 1 hour while continuously supplying ethylene to maintain this pressure. After the reaction was completed, unreacted gas was removed and the polymer was separated and dried to obtain 5 g of white polyethylene. The bulk density of the obtained polyethylene was 0.20g/
cm ³ , MI _2.16 was 0.50, and FR was 33.

[Brief explanation of the drawing]

FIG. 1 is a flowchart showing the steps for preparing a catalyst used in the method of the present invention.

Claims (1)

[Claims] 1 (A) Magnesium compound, silicon halide,
The solid content produced by reacting a compound containing at least titanium, magnesium, and a halogen obtained by reacting alcohol and titanium halide with tetraalkoxyzirconium and tetrahalogenated zirconium and/or tetraalkoxytitanium has the general formula _AlR ^1o
A solid obtained by reacting an organic aluminum halide compound represented by X ¹ _3-o (wherein R ¹ is an alkyl group, X ¹ is a halogen atom, and n is 0<n<3) A method for producing polyethylene, which comprises polymerizing ethylene using a catalyst containing a product and (B) an organoaluminum compound as an active ingredient. 2 The organoaluminum compound has the general formula AlR ² _n X ² _3-n (wherein R ² is an alkyl group, X ² is a halogen atom, and m is 0<m≦3).
Alternatively, the general formula AlR ³ _k (OR ⁴ ) _3-k (where R ³ , R ⁴
represents an alkyl group, and k is 0<k≦3. ) The manufacturing method according to claim 1, which is represented by: