JPS584931B2 - Ethylene polymerization method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for polymerizing ethylene, and more particularly to a method for efficiently polymerizing ethylene using a specific catalyst.

Conventionally, when polymerizing ethylene, a magnesium-containing compound such as magnesium halide, magnesium alkoxide, etc. is used as a catalyst carrier, and a substance obtained by reacting this substance with titanium halide becomes a component of a highly active catalyst. It has been known.

Regarding the use of the reaction product of magnesium alkoxide and titanium halide as a catalyst component, Japanese Patent Publication No. 46
Although it is specifically described in Japanese Patent No. 34098, the catalyst activity and the quality of the polyethylene obtained are not satisfactory.

Furthermore, a method of reacting magnesium alcohoxide with an organic aluminum or halogen agent and reacting with a titanium compound (Special Public Showa 47-4 34 35 Bulletin, Special Prince 51-30118) or magnesium -alcoholicoxy A method of reacting with a titanium compound in the presence of a compound, a halogenated silane or a boron compound (Japanese Patent Publication No. 51-30118, JP-A-47-32081, JP-A-52-98076, JP-A-Sho 51- 40915) is known.

Although these methods can be expected to increase activity to some extent,
However, it is difficult to say that the results are satisfactory.

On the other hand, a method of reacting metallic magnesium with alcohol in the presence of silicon halide (Japanese Patent Publication No. 50-23864
Although it has also been proposed, it is not desirable in terms of carrier preparation and activity.

The ultimate purpose of the methods for high-activity polymerization of ethylene as described above is to further increase the activity, omit the catalyst removal step, simplify the manufacturing process, and improve the quality of the resulting product. The more the activity is improved, the more desirable it is.

In view of this, the present inventors polymerized ethylene using a catalyst containing a reaction product of a magnesium compound and a titanium halide, or a reaction product obtained by further treating this with a halogen-containing organoaluminum compound. Various studies were conducted regarding the method.

As a result, a catalyst prepared using a mixture of magnesium dialkoxide and magnesium sulfate as a magnesium compound showed a higher titanium loading and polymerization activity than the catalyst described in Japanese Patent Publication No. 46-34098, which uses magnesium dialkoxide alone. It was found that there was a significant increase in

The present invention was completed based on this knowledge.

That is, the present invention provides (A1) a titanium-containing solid product obtained by contacting a magnesium compound with a titanium halide, or (A2) a titanium-containing solid product obtained by further treating this solid product with a halogen-containing organoaluminum compound. and (B) a method for polymerizing ethylene using a catalyst comprising an organoaluminum compound as a component, the method comprising using a mixture of magnesium dialkoxide and magnesium sulfate as the magnesium compound. It is something that
The magnesium dialkoxide used in the present invention is usually represented by the general formula Mg(OR)2, where R is an alkyl group, alkenyl group, or aryl group having 1 to 20 carbon atoms, preferably 1 to 6 carbon atoms. , cycloalkyl group, arylalkyl group, alkylaryl group, etc.

Specifically, magnesium dimethoxide, magnesium diethoxide, magnesium dipropoxide, magnesium dibutoxide, magnesium dicyclohexoxide,
Magnesium dibenzoxide and the like are preferred.

In addition to the above-mentioned magnesium dialkoxides of the present invention, composite alkoxides with other metals and monoalkoxides having halogen carboxyl groups, hydroxyl groups, etc. can also be used.

Commercially available magnesium dialkoxides can be used, but they may also be produced by reacting metallic magnesium and alcohol.

In the latter case, the efficiency and polymerization activity can be improved, especially if the reaction is carried out in the presence of magnesium sulfate to be mixed.

The preparation method when using metallic magnesium is as follows.

That is, a predetermined amount of magnesium metal, magnesium sulfate, and excess alcohol are added to a hydrocarbon solvent such as hexane or heptane, or the alcohol itself is used as a solvent and heated to 70 to 100°C to cause a complete reaction.

Next, the solvent is distilled off, and the resulting solid is thoroughly dried and pulverized.

For pulverization, a known method such as a ball mill may be used.

The alcohol used here includes methanol, ethanol, isopropanol, butanol, octanol, and the like.

As the magnesium compound of the present invention, a mixture of the above-mentioned magnesium dialkoxide and magnesium sulfate is used.

The mixing ratio in this case is not particularly limited and may be selected appropriately depending on various conditions, but generally 0.05 to 5.
The range is 0 mol.

Outside this range, the effect of improving the activity of the catalyst observed synergistically will be extremely low.

The titanium-containing solid product, which is the component (A1) of the catalyst used in the present invention, is obtained by first dispersing the above magnesium dialkoxide and magnesium sulfate in a predetermined ratio in an inert hydrocarbon solvent such as hexane, heptane, or cyclohexane. It is obtained by adding titanium halide in an amount equivalent to or more than the above-mentioned mixture of magnesium compounds to the system and carrying out the reaction at 70 to 150°C for 30 minutes to 5 hours.

The titanium halides that can be used here include tetravalent, trivalent or divalent titanium halides, more specifically TiBr4, TiCZ4+Ti (OR'
)Ct3j Ti (OR)Ct2T Ti (OR'
)3CtITtBr3? TxCt3 + TtCt2
etc. (where R/ represents an alkyl group.

) can be given. After the reaction is complete, the solid product is thoroughly washed with an inert hydrocarbon solvent such as hexane, heptane, cyclohexane, benzene, toluene, xylene, etc., and further washed with an appropriate inert solvent such as hydrocarbon in an inert gas. It is dispersed in concentration and adjusted as a catalyst component.

Further, the titanium-containing solid product which is the component (A2) of the catalyst used in the present invention is obtained by washing the solid product which is the component (A1) obtained by the above reaction, dispersing it in an inert solvent, and then dispersing this solid product in an inert solvent. It is produced by adding a halogen-containing organoaluminum compound to the system and reacting at room temperature to 60°C for 0.5 to 10 hours.

Note that the amount of the halogen-containing organoaluminum compound added is not particularly limited, but it is usually in the range of 0.5 to 5 moles of aluminum atoms per 1 mole of titanium atoms in the solid product dispersed in the reaction system. It is preferable to adjust it so that

The halogen-containing organoaluminum compound used here includes dialkylaluminum monohalides such as dimethylaluminum monochloride, diethylaluminum monochloride, dipropylaluminum monochloride, and diisobutylaluminum monochloride, or ethylaluminum dichloride, propylaluminum dichloride, Examples include alkyl aluminum dihalides such as isobutyl aluminum dichloride, and further alkyl aluminum sesquihalides such as ethyl aluminum sesquichloride.

After the reaction with this halogen-containing organoaluminium compound, titanium, which is the component (A2) obtained, is obtained. As in the case of component (A1) above, the solid product is thoroughly washed with an inert hydrocarbon solvent, and further dispersed in an inert solvent such as a hydrocarbon in an inert gas at an appropriate concentration. Adjust as a catalyst component.

The method of the present invention comprises a titanium-containing solid product as component (A) or component (A2) prepared as described above, and (
B) A catalyst consisting of an organoaluminum compound is used as the component.

In polymerizing ethylene, a dispersion of the titanium-containing solid product and an organoaluminum compound are added to the reaction system as a catalyst, and then ethylene is introduced into the system.

There are no particular restrictions on the polymerization method and conditions, and solution polymerization,
Both suspension polymerization and gas phase polymerization are possible, and both continuous polymerization and discontinuous polymerization are possible.

For example, in the case of solution polymerization or suspension polymerization, the amount of the catalyst component added is determined by adding the titanium-containing solid product, which is the component (AI) or component (A2), to the o. ooi to 5 mmol/l, while the organoaluminum compound as component (B) was 0.
．． It is preferable to set it as 01-10 mmol/l.

The solvent for the reaction system is preferably a hydrocarbon such as n-hexane or n-heptane, and the ethylene pressure in the reaction system is between normal pressure and
The reaction temperature was selected to be in the range of 50 kg/cm, and the reaction temperature was 60 to 1.
20°C is preferred.

Molecular weight adjustment during polymerization can be carried out by known means, such as hydrogen.

The hydrogen pressure is usually preferably about 60% of the ethylene pressure.

Examples of organoaluminum compounds which are component (B) of the catalyst used in the method of the present invention include trialkylaluminum compounds such as trimethylaluminum, triethylaluminum, triisopropylaluminum, triisobutylaluminum, and trioctylaluminum, and diethylaluminum monochloride. , diimpropylaluminum monochloride, diisobutylaluminum monochloride, dioctylaluminum monochloride, and other dialkylaluminum monohalides are suitable.

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.

Note that the catalyst used in the method of the present invention may further contain an organic metal such as organic zinc.

Since the catalyst used in the method of the present invention uses a mixture of magnesium dialkoxide and magnesium sulfate as the magnesium compound, the polymerization activity is synergistically improved compared to conventional magnesium dialkoxide alone.

In addition, (A2) obtained by further treating the solid product which is the component (A1) with a halogen-containing organoaluminum compound
Catalysts containing these components also have enhanced single-family polymerization activity.

Furthermore, the polyethylene obtained by the method of the present invention has a low molecular weight and is of high density and high quality.

Therefore, according to the method of the present invention, high-quality polyethylene can be produced extremely efficiently and economically, and therefore, the method of the present invention is effective as a process for producing high-density polyethylene.

Next, the method of the present invention will be explained in more detail with reference to Examples.

Example 1 (1) Production of catalyst 6.8 g (60 mmol) of magnesium diethoxide,
Magnesium sulfate7. 1 g (60 mmol) was suspended in 150 ml of n-heptane, the temperature was raised, and 17 ml (approximately 150 mmol) of TiCl4 was added under reflux to carry out a reaction for 3 hours.

After the reaction, the temperature was lowered, the supernatant liquid was taken out, 150 ml of n-heptane was newly added, and the mixture was washed in the same manner three times using the decanting method.

Furthermore, 120 ml of n-heptane was newly added to obtain a catalyst slurry (A1).

The amount of titanium supported was measured by a colorimetric method and was 110 mg-Ti.
/g of carrier.

An amount equivalent to 30 mmol of titanium atoms was collected from the catalyst slurry (A1), 30 mmol of ethylaluminum sesquichloride was added thereto, and the mixture was reacted at 40°C for 5 hours.

Washing with n-heptane was repeated to obtain a catalyst slurry (A2) of n-heptane.

The amount of titanium supported was 63 -Ti/g per carrier.

(2) Polymerization of ethylene The autoclave in Step 14 was purged with argon, 400 ml of n-hexane, 0.08 mmol of titanium atoms and 8 mmol of triethylaluminum were added to each of the above catalyst slurries (AI) and (A2), and heated to 80°C. The temperature was raised, and polymerization was carried out for 1 hour while continuously supplying hydrogen at a rate of 3 kg/cm and ethylene at a rate of 5 kg/cm.

The results are shown in Table-1.

Comparative Example 1 A supported catalyst was produced in the same manner as in Example 1 using 11.5 g (96 mmol) of magnesium sulfate.

In addition, in the method for obtaining the catalyst slurry (A2), the amount of ethylaluminum sesquichloride used was 1 in molar ratio to titanium atoms.

The amount of titanium supported in the catalyst slurry (A1) is 16 mg - Ti
/g-support, the amount of titanium supported in the catalyst slurry (A2) is 9
mgTi/g-carrier.

Furthermore, ethylene was polymerized using this catalyst in the same manner as in Example 1.

The results are shown in Table-2.

Comparative Example 2 11.6 g (102 mmol) of magnesium diethoxide was suspended in 120 ml of n-heptane, and the suspension was heated to reflux.

3.1 g (120 mmol) of TiCt41 was added to this, and a reaction was carried out for 3 hours.

A catalyst slurry (A1) was obtained in the same manner as in Example 1.

The amount of titanium supported was 267 mg-Ti/g per carrier.

From this slurry, an amount equivalent to 55 mmol of titanium atoms was collected, and 55 mmol of ethylaluminum sesquichloride was added to this.
mmol was added, reacted at 40°C for 5 hours, and washed to obtain a catalyst slurry (A2).

The amount of titanium supported was 130 mg-Ti/g per carrier.

Furthermore, ethylene was polymerized using this catalyst in the same manner as in Example 1.

The results are shown in Table-3. Example 2 (1) Production of catalyst 6.8 g (60 mmol) of magnesium diethoxide,
2.4 g (20 mmol) of magnesium sulfate was suspended in 150 ml of n-heptane, and the temperature was raised.

17 ml (approximately 150 mmol) of TiCA was added at reflux temperature, and the reaction was carried out for 4 hours.

After the reaction, the temperature was lowered and washing was performed in the same manner as in Example 1 to obtain a catalyst slurry (A1).

The amount of titanium supported was 190 mg-Ti/g per carrier.

(2) Polymerization of ethylene 400 ml of n-hexane, 6 mmol of triethylaluminum, and an amount equivalent to 0.08 mmol of titanium atoms in the catalyst slurry were added to a 1-ton autoclave.
Polymerization of ethylene was carried out in the same manner.

Polyethylene 5 after 1 hour of polymerization 7. 1 f was obtained, and the catalytic activity was 15,20 per gram of titanium atom per hour.
0 g, and the melt index was 13.

Example 3 (1) Production of catalyst 6.8 g (60 mmol) of magnesium diethoxide and 21.3 g (180 mmol) of magnesium sulfate were suspended in 150 ml of n-heptane and heated.

5 ml (approximately 500 mmol) of T iCt45 was added at reflux temperature and reacted for 4 hours.

Washing was performed in the same manner as in Example 1, and the catalyst slurry (
A1) was obtained.

The amount of titanium supported was 25 mg-Ti/g per carrier.

Further, an amount equivalent to 10 mmol of titanium atoms was collected from the catalyst slurry (A1), 30 mmol of ethylaluminum dichloride was added thereto, the reaction was carried out at 40°C for 3 hours, and normal heptane washing was repeated to form a catalyst slurry of normal heptane (A2). ) was obtained.

The amount of supported titanium is 16~=Ti/? It was a carrier.

(2) Polymerization of ethylene In Example 1, ethylene was polymerized in the same manner as in Example 1, except that 0.2 mmol of titanium atoms and 4 mmol of triethylaluminum were used in the catalyst slurry.

In the catalyst using slurry (A1), polyethylene 122
g is obtained, the catalyst activity is 12,700 g per hour at 1 g of titanium atom, and the melt index is 12.
In the catalyst using slurry (A2), polyethylene 274
? was obtained, the catalytic activity was 28,500 g per gram of titanium atom per hour, and the melt index was 15.
Met.

Examples 4 to 6 The catalyst slurry (A2) of Example 1 was used, and the conditions were the same as in Example 1, except that the amount of catalyst used, the type and amount of organoaluminum compound, ethylene pressure, and hydrogen pressure were changed. Polymerization of ethylene was carried out.

The results are shown in Table 4. In Example 4, Al(C2H5)2
Cl was used, and in Examples 5 and 6, At(C2H5)3 was used.

The titanium atom is 1 g. Polyethylene yield per hour (ff) Example 7 (1) Production of catalyst 4.8 g (200 mmol) of metallic magnesium and 24 g (200 mmol) of commercially available anhydrous magnesium sulfate were dispersed in 120 ml of ethanol. After reacting at room temperature for 30 minutes, the temperature was raised and the reaction was carried out under reflux for 5 hours, excess ethanol was distilled off, and the mixture was dried under reduced pressure at 80° C. for 4 hours.

This solid was ground in a ball mill at room temperature for 4 hours, and this 1
5.3 g of TiC was suspended in 100 ml of n-heptane.
t419g (11ml, 100mmol) was added, and the temperature was raised to reflux (98°C).

After reacting for 5 hours, the temperature was lowered, the supernatant liquid was taken out, 100 g of n-heptane was newly added, the mixture was stirred, allowed to stand, and washed by the decanting method.

This operation was repeated three times, and n-heptane was newly added to obtain a catalyst slurry.

The amount of supported titanium was determined by titration method.5. 4mg-T
i/g monocarrier.

(2) Polymerization of ethylene A 1-liter autoclave was purged with argon, and 400 ml of n-heptane, 6 mmol of triethylaluminum, 0.02 mmol of titanium atoms, and an equivalent amount of the above catalyst slurry were added, and the temperature was raised.

Polymerization was carried out at 80°C for 1 hour while continuously supplying hydrogen at 2 kg/cm' and ethylene at 6 kg/cm'.

Melt index 0 at 190℃ and 2.16k9 load
．． 106 g of 46 polyethylene were obtained.

The catalytic activity of this product is 1 g of titanium atom per hour.
It was 13,200g.

Comparative Example 2 (1) Production of catalyst 5.8 g of solid obtained by reacting metallic magnesium and ethanol without adding magnesium sulfate (magnesium 5
0 mmol) suspended in 120 g of n-heptane,
Tict41 3. 1 g (120 mmol) was added, and the reaction was carried out under reflux (98°C) for 3 hours.

Washing was repeated in the same manner as in Example 1 to obtain a catalyst slurry with a titanium loading of 260 mg-Ti/g-support.

(2) Polymerization of ethylene In Example 7, ethylene was polymerized in the same manner as in Example 7, except that a catalyst slurry in an amount equivalent to 0.2 mmol of titanium atoms was used.

After 15 hours of polymerization, 141 g of polyethylene with a melt index of 0.10 was obtained.

The catalytic activity of this product is 1 g of titanium atom per hour.
It was 0.500 g.

Examples 8 to 9 (1) Production of catalyst A catalyst was produced in the same manner as in Example 7 except that the amount of magnesium sulfate added was changed.

The results are shown in Table-5. (2) Polymerization of ethylene Ethylene polymerization was carried out under the same conditions as in Example 7 using an amount equivalent to 0.02 mmol of titanium atoms of the catalyst prepared in 1) above.

The results are shown in Table-6.

Claims (1)

[Scope of Claims] 1 (A1) A titanium-containing solid product obtained by contacting a magnesium compound with a titanium halide, and (
B) A method for polymerizing ethylene using a catalyst containing an organoaluminum compound, which comprises using a mixture of magnesium dialkoxide and magnesium sulfate as the magnesium compound. 2. The method according to claim 1, wherein the magnesium dialkoxide is obtained by reacting metallic magnesium with alcohol in the presence of magnesium sulfate. 3 (A2) Using a titanium-containing solid product obtained by treating a solid product obtained by contacting a magnesium compound with a titanium halide with a halogen-containing organoaluminum compound and (B) a catalyst containing the organoaluminum compound as a component. A method for polymerizing ethylene, characterized in that a mixture of magnesium dialkoxide and magnesium sulfate is used as the magnesium compound. 4. The method according to claim 3, wherein the magnesium dialkoxide is obtained by reacting metallic magnesium with alcohol in the presence of magnesium sulfate.