JPS6251285B2 - - 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 attempting to widen the molecular weight distribution of polyethylene, the catalyst activity decreases, resulting in lower production efficiency and the need for a large amount of catalyst, so a step is required to remove the catalyst from the resulting polyethylene. There were drawbacks such as having to do it.

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 a solid content produced by reacting a compound containing at least titanium, magnesium, and halogen with tetraalkoxyzirconium and/or zirconium tetrahalide, which has the general formula Ti(OR ¹ ) _o X ¹ _4-o ( In the formula, R ¹ is an alkyl group, X ¹ is a halogen atom, and n is 0
≦n<4. The present invention provides a method for producing polyethylene, which is characterized by using a solid product obtained by reacting a halogen-containing titanium compound represented by B) and a catalyst containing an organoaluminum compound B as an active ingredient.

The catalyst used in the method of the present invention is prepared from the above-mentioned components A and B, and among these, the compound containing at least titanium, magnesium, and halogen, which is the base of the solid product that is component A, is particularly You can think of various things without being limited. Specifically, the following can be cited as suitable examples. That is,
Solid substances obtained by reacting titanium halides with magnesium inorganic compounds such as magnesium oxide, magnesium hydroxide, magnesium carbonate, magnesium sulfate, and magnesium halides, or by reacting various magnesium compounds with silicon halides,
Examples include solid substances obtained by reacting alcohol and titanium halide in sequence, and solid substances obtained by reacting dialkoxymagnesium such as magnesium diethoxide with magnesium sulfate and titanium halide. In addition, silicon halides or organosilicon compounds (e.g. SiCl ₄ ,
_{CH3OSiCl3 ,} ( _CH3O ) _{2SiCl2 ,} ( _CH3O ) _3SiCl ,Si
(OCH ₃ ) ₄ , C ₂ H ₅ OSiCl ₃ , (C ₂ H ₅ O) ₂ SiCl ₂ ,
(C ₂ H ₅ O) ₃ SiCl, Si(OC ₂ H ₅ ) ₄ , etc.) and a solid material obtained by reacting titanium halides can also be used, and in addition, dialkoxymagnesium and MgCl _{2.6C 2} H Reacting alcohol adducts of magnesium halides such as ₅ OH,
It is also possible to use a solid material obtained by reacting a titanium halide with a product obtained by subsequent alcohol treatment.

A solid product, which is 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 and/or zirconium tetrahalide. Here, specific examples of the tetraalkoxyzirconium include tetramethoxyzirconium, tetraethoxyzirconium, tetrapropoxyzirconium, and tetrabutoxyzirconium, among which tetrabutoxyzirconium is particularly preferred. On the other hand, specific examples of zirconium tetrahalide include tetrachlorozirconium and tetrabromzirconium. 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. 0.1 to 20% of tetraalkoxyzirconium
mol, preferably in the range of 0.2 to 10 mol, and zirconium tetrahalide is appropriately determined in the range of 0 to 20 mol. Other conditions for the above reaction include a temperature of 0 to 200°C, preferably 20 to 150°C, a reaction time of 5 minutes to 5 hours, preferably 30 minutes to 3 hours, and pentane, hexane, heptane, octane, etc. It is preferable to use an inert hydrocarbon such as , cyclohexane, benzene or toluene as the solvent.

After thoroughly washing the solid content generated in the above reaction,
Further, this solid content is reacted with a halogen-containing titanium compound represented by the general formula Ti(OR ¹ ) _o X ¹ _4-o . As this halogen-containing titanium compound, various compounds can be considered as long as R ¹ , X ¹ , and n in the above formula are appropriately determined within the definition, but for example, TiCl ₄ ,
_{TiBr4 ,} Ti( _OCH3 ) _Cl3 ,Ti( _OC2H5 ) _2Cl2 , _Ti
Preferred examples include (OC ₂ H ₅ ) ₃ Cl and mixtures thereof. The amount of the halogen-containing titanium compound to be blended is usually 1 to 200 mol, preferably 10 to 100 mol, per 1 mol of titanium atoms in the solid content. In addition, this reaction, that is, the reaction between the solid content and the halogen-containing titanium compound, is carried out at 20 to 200°C, preferably at 50°C.
~150℃ for 5 minutes to 10 hours, preferably 30 minutes to 5 hours
It only needs to be carried out under certain time conditions, and in addition, pentane,
Inert hydrocarbons such as hexane, heptane, octane, cyclohexane, benzene, toluene can be used as solvents.

In the method of the present invention, the solid product obtained by the above reaction is washed as necessary and used as component A of the catalyst.

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 (in the formula,
R ² is an alkyl group, X ² is a halogen atom, and m satisfies 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. ) is used. Specific examples of the above organoaluminum compounds include trimethylaluminum, triethylaluminum,
Triisopropylaluminium, triisobutylaluminum, diethylaluminum monochloride, diisopropylaluminum monochloride,
Diisobutylaluminum monochloride, dioctylaluminum monochloride, ethylaluminum dichloride, diethylaluminum monoethoxide, isopropylaluminum dichloride,
Examples include 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 component A and component B in this catalyst is not particularly limited, but usually 5 to 1000 aluminum atoms in component B to 1 titanium atom in component A (molar ratio), preferably 20 to 500.
(molar ratio). There is no particular restriction on the amount of the catalyst consisting of both components A and B used in the production of polyethylene, and it can be determined according to various conditions, but it is usually calculated in terms of titanium atoms.
It should be between 0.001 and 10 mmol/, preferably between 0.005 and 0.5 mmol/.

When producing polyethylene by polymerizing ethylene by the method of the present invention, a catalyst prepared from the above components A and B is added to the reaction system, 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 catalyst for the reaction system, inert solvents such as butane, heptane, hexane, cyclohexane, heptane, benzene, and toluene are preferred. Furthermore, the ethylene pressure in the reaction system is 2
-100Kg/ ^cm2 , preferably 5-50Kg/ ^cm2 , and the reaction temperature is 20-200℃, preferably 50-150℃,
The desired polyethylene can be obtained by reacting for 5 minutes to 10 hours, preferably 30 minutes to 5 hours. 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 catalyst as described above,
It has a high catalytic activity, and a sufficient effect can be obtained 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.

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) and 3.7 g (22 mmol) of silicon tetrachloride were added, and while stirring at 20°C, 2.0 g (33 mmol) of isopropyl alcohol was added dropwise over 30 minutes.Then, the temperature was raised and refluxed for 3 hours. Made it react. Next, 42 g (220 mmol) of titanium tetrachloride was added dropwise, and the reaction was carried out under reflux for 3 hours. After cooling and standing, the supernatant liquid was removed, and the generated solid substance was
- The target compound containing titanium, magnesium and halogen was obtained by washing with hexane. The titanium content in this compound was 6.2% by weight.

(2) Production of component A of the catalyst.

In a 200ml flask, add dry n-hexane.
To 50 ml of the compound obtained in (1) above, 8.8 mmol of magnesium (1.3 mmol of titanium) and 3 mmol of tetrabutoxyzirconium were added, and the mixture was reacted at 70° C. for 2 hours with stirring. The system was then cooled to room temperature, left to stand, the supernatant was removed, and the precipitate was washed once with 50 ml of n-hexane, followed by the addition of 8.8 mmol of titanium tetrachloride and 70
The reaction was carried out at ℃ for 3 hours. After cooling, the precipitate was
- Washed 5 times with 50 ml of 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 0.005 mmol of titanium, the solid product which is the A component of the catalyst obtained in (2) above. In addition, 80℃
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 139 g of white polyethylene. The bulk density of the obtained polyethylene was 0.29 g/cm ² , and _the MI _2.16 was
0.52, FR was 46.

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

8.8 mmol of the compound obtained in Example 1 (1) as magnesium (1.3 mmol as titanium), 1.0 mmol of tetrabutoxyzirconium, and 50 ml of dry n-hexane were added to a 200 ml flask, and the mixture was stirred for 70 ml. The reaction was carried out at ℃ for 2 hours. Next, 22 mmol of titanium tetrachloride was added to this system, and the mixture was reacted at 70°C for 3 hours. After cooling, the precipitate was washed 5 times with 50 ml of n-hexane to remove the catalyst A.
A solid product was obtained.

(2) Manufacture of polyethylene.

Ethylene polymerization was carried out under the same conditions as in Example 1 except that the solid product obtained in (1) above was used as component A of the catalyst. As a result, polyethylene
84g was obtained, and the bulk density of this polyethylene was 0.27
g/cm ² , MI _2.16 was 0.41, _and FR was 46.

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

In a 200 ml flask, add 8.8 mmol of the compound obtained in Example 1 (1) as magnesium (1.3 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 the mixture was reacted at 70° C. for 3 hours with stirring. Next, 22 mmol of titanium tetrachloride was added to this system and the mixture was heated at 70°C.
Allowed time to react. After cooling, let it stand and remove the supernatant liquid.
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, 2.0 mmol of triisobutylaluminum, which is the B component of the catalyst, and 0.01 mmol of titanium, the solid product which is the A component of the catalyst obtained in (1) above. In addition, the temperature was raised to 80°C. Next, 3 kg/cm ² of hydrogen and 5 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 105 g of white polyethylene. The bulk density _of the obtained polyethylene was 0.25 g/cm ² , MI _2.16 was 0.38, FR
was 54.

Example 4 (1) Production of component A of the catalyst.

Into a 200 ml flask were added 8.8 mmol of the compound obtained in Example 1 (1) as magnesium (1.3 mmol as titanium), 44 mmol of ethylaluminum dichloride, and 50 ml of dry n-hexane, and the mixture was heated at 70°C with stirring. The reaction was carried out for 1 hour. After cooling, let it stand, remove the supernatant liquid, and dry it.
Washed with hexane. Next, 50 ml of dry n-hexane was added to the resulting solid slurry, 4.0 mmol of tetrabutoxyzirconium was added, and the mixture was reacted at 70°C for 3 hours. Further, 22 mmol of titanium tetrachloride was added and the mixture was reacted at 70°C for 3 hours. . After cooling, the mixture was allowed to stand, the supernatant liquid was removed, and the mixture was washed with dry 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, 2.0 mmol of triisobutylaluminum, which is the B component of the catalyst, and 0.02 mmol of the solid product, which is the A component of the catalyst obtained in (1) above, as titanium. In addition, the temperature was raised to 80°C. Next, ethylene was polymerized under the same conditions as in Example 3 to obtain 98 g of polyethylene. The bulk density of the obtained polyethylene was 0.26 g/cm ³ , and MI _{2.16 was}
0.13, FR was 63.

Comparative example (1) Production of catalyst components.

In a 200ml flask, add dry n-hexane.
50 ml of the compound obtained in Example 1 (1) was added with 8.8 mmol of magnesium (1.3 mmol of titanium) and 8.8 mmol of titanium tetrachloride, and the reaction was carried out at 70° C. for 3 hours with stirring. After the reaction was completed, the mixture was cooled and allowed to stand, the supernatant liquid was removed, and the mixture was further washed with dry n-hexane to obtain a solid product as a catalyst component.

(2) Manufacture of polyethylene.

In a 1-volume stainless steel autoclave, 400 ml of dry n-hexane, 2.0 mmol of triisobutylaluminum, which is component B of the catalyst, and 0.005 titanium of the solid product obtained in (1) above were placed in a 1-volume stainless steel autoclave.
mmol was added and the temperature was raised to 80°C. 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, the unreacted gas was removed and the polymer was separated and dried, resulting in 225g of white polyethylene.
Obtained. The bulk density of the obtained polyethylene is 0.29
g/cm ³ , MI _2.16 was 0.50, _and FR was 31.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the preparation process of a catalyst used in the method of the present invention.

Claims (1)

[Scope of Claims] 1 A: A solid content produced by reacting a compound containing at least titanium, magnesium and a halogen with tetraalkoxyzirconium and/or zirconium tetrahalide, which has the general formula Ti
(OR ¹ ) _o X ¹ _4-o (In the formula, R ¹ is an alkyl group, X ¹ is a halogen atom, and n is 0≦n<4.)
A method for producing polyethylene, which comprises using a solid product obtained by reacting a halogen-containing titanium compound represented by the formula B, and a catalyst containing an organoaluminum compound B as an active ingredient. 2 The organoaluminum compound has the general formula
AlR ² _n X ² _3-n (In the formula, 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: