JPS588692B2 - Polyethylene manufacturing method - 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 highly active polymerization of polyethylene using a modified magnesium halide as a catalyst carrier.

It is well known that magnesium halides are used as carrier raw materials for supporting transition metals in conventional high-activity polymerization catalysts for polyolefins, but when transition metals are directly supported on magnesium halides, the amount supported is very small and the activity is low. It turns out it's not expensive.

Furthermore, various proposals have been made to overcome this drawback, such as pre-treatment before contact with transition metals, or the presence of various compounds during reaction with transition metals.

For example, the raw material is a magnesium halide electron donor adduct produced by coordinating an electron donor such as water, alcohol, or ester to magnesium halide (Japanese Patent Publication No. 46-34092, Japanese Patent Publication No. 48-19794). (Japanese Patent Publication No. 53-17
No. 96, JP-A No. 49-88983), those using activated anhydrous magnesium halide obtained by activation with a ball mill etc. or by heating an alcohol or water adduct (Japanese Patent Publication No. 47-41676) )
, one in which an alcohol pretreated product of magnesium dihalide is reacted with an organic metal of Groups 1 to 3 of the periodic table (JP-A-49-119980), and one in which magnesium dihalide and aluminum chloride are co-precipitated from an alcohol solution. (Japanese Unexamined Patent Publication No. 130692/1983) is known.

However, the method of forming a pre-treated adduct with an electron donor requires a great deal of care and effort in adjusting the amount of addition and other treatments, and further processing them increases the number of steps. All of these methods have advantages and disadvantages, such as a decrease in activity even if the amount of titanium supported increases, or a low bulk specific gravity of the resulting polyethylene.

The present inventors, in the process of conducting detailed studies on highly active polymerization of ethylene using magnesium chloride, found that by bringing magnesium chloride into contact with a specific amount of a halogen-containing titanium compound and alcohol, and then supporting titanium halide. It was found that the activity increased dramatically, but considering that the bulk specific gravity of the obtained polyethylene did not increase much, further studies were conducted.

As a result, it was found that by treating magnesium chloride with a halogen-containing titanium compound and alcohol and then carrying the titanium halide in the presence of an alkoxy-containing silicon compound, the activity was further increased and the bulk specific gravity of polyethylene was also increased. Heading: The present invention has been completed.

That is, the present invention provides a method for producing polyethylene using a catalyst containing (A) a reaction product of a magnesium compound and a titanium halide and (B) an organoaluminum compound, in which (3) magnesium chloride is used as a component.
．． Obtained by contact reaction with 1 to 2 times the molar amount of a halogen-containing tetravalent titanium compound and 0.1 times mole or more of alcohol, and then reacting the resulting solid substance with a titanium halide in the presence of an alkoxy-containing silicon compound. A method for producing polyethylene is provided, characterized in that a solid product is used.

As the magnesium chloride used in the present invention, unactivated magnesium chloride such as commercially available anhydrous magnesium chloride is sufficient, but it is of course possible to use anhydrous magnesium chloride activated by a conventionally known method.

Furthermore, a mixture with a known metal compound carrier that does not inhibit ethylene polymerization may be used.

The component (A) in the catalyst used in the method of the present invention is adjusted as follows.

That is, the magnesium chloride described above is usually first dispersed in an inert solvent.

The amount of dispersion is not particularly limited, but for convenience of operation, the amount of dispersion is
Subsequently, a halogen-containing tetravalent titanium compound and alcohol are added to the dispersion, which is preferably 50 to 500 g per liter, and reacted with stirring at a predetermined temperature and time to modify the magnesium chloride.

The reaction temperature at this time is usually 0-150'C, especially 50-150'C.
It is preferable to adjust the temperature to 00°C because it is efficient, the polymerization activity of the obtained catalyst is high, and the bulk specific gravity of polyethylene produced using this catalyst is also large.

Although the reaction time depends on the reaction temperature, it is usually 5 minutes to 5 hours.
Preferably << is 0.5 to 3 hours.

Note that the order in which the three components are contacted in this reaction is not particularly limited to this. It can be divided into two steps, such as first reacting magnesium chloride and a halogen-containing tetravalent titanium compound, and then adding alcohol to the reaction system. You may do so.

The halogen-containing tetravalent titanium compound used in the above reaction is
General formula: XnTi(OR)4-n (wherein X is a halogen atom, R is an alkyl group having 1 to 4 carbon atoms, and n is an integer of 1 to 4).

] Compounds represented by these are preferred.

Examples of the halogen-containing tetravalent titanium compound include titanium tetrahalide and alkoxy titanium halide, specifically TiCl4, TiBr4, CH30T.
Examples include iC■3, (C2H50)2TiC12, and the like.

Among these, high halogen content, especially titanium tetrachloride (T
iC14) is most preferred.

The amount of the halogen-containing tetravalent titanium compound added is 0.1 to 2 times the molar amount of the above magnesium chloride.

In this case, it is preferable to use an amount such that the halogen atoms contained in the titanium compound are at least 0.5 times the molar amount of the magnesium compound.

If the amount of the titanium compound added is less than 0.1 times the molar amount of magnesium chloride, the activity of the catalyst and the bulk specific gravity of the produced polymer will not be sufficiently improved.

Furthermore, when a large amount of a halogen-containing tetravalent titanium compound is used, a large amount of titanium is supported in the modified product at this stage, as in the past, and no improvement in polymerization activity is observed, rather the bulk density of the resulting polymer is low. It also wastes the reactant, so do not exceed twice the molar amount of magnesium chloride.
Preferably, << is used in an equimolar amount or less.

On the other hand, the alcohol used in the above reaction is a straight-chain or side-chain aliphatic or alicyclic alcohol, with primary or secondary alcohols having 1 to 6 carbon atoms being particularly preferred.

Specifically, methanol, ethanol, propanol, isopropanol, butanol, isobutanol, amyl alcohol, octanol, etc. can be mentioned.

The amount of alcohol added is 0.1 times or more, preferably 0.5 times or more by mole, relative to the magnesium chloride.

There is no particular restriction on the upper limit of the amount to be added, but since using a large amount will result in waste of the titanium compound as described below, the amount is usually around the same amount as the halogen contained in the titanium compound.

If the amount of alcohol used is lower than this lower limit, the desired improvement in polymerization activity or bulk specific gravity of the polymer cannot be sufficiently expected.

Furthermore, the solvent used in the above reaction is not particularly limited as long as it is inert and does not react with the above-mentioned magnesium chloride, halogen-containing tetravalent titanium compound, and alcohol. Examples include solvents.

Specifically, butane, pentane, hexane, heptane, cyclohexane, etc. are suitable.

Although the reaction using a solvent as described above is a preferred embodiment of the present invention, it is also possible to carry out the reaction without a solvent.

In this case, for example, the above-mentioned magnesium chloride, halogen-containing 4
A predetermined ratio of a titanium compound and an alcohol may be directly mechanically mixed and reacted using a ball mill or the like.

The modified magnesium chloride solid material thus obtained is used in the next reaction either in the reaction dispersion as it is or after washing and separating the modified solid.

Note that the modified product may be further treated with an organoaluminum compound and used in the next reaction.

Component (3) in the catalyst used in the method of the present invention is a substance obtained by reacting the above-mentioned modified magnesium chloride with a titanium halide in the presence of an alkoxy-containing silicon compound.

The alkoxy-containing silicon compound used here has the general formula XmSi(OR)1-m (wherein X is a halogen atom, R
represents an alkyl group having 1 to 4 carbon atoms, and m represents an integer of 0 to 3.

] Compounds represented by these are preferred.

Examples of the alkoxy-containing silicon compounds include monoalkoxyhalogenated silanes, dialkoxyhalogenated silanes, trialkoxyhalogenated silanes, and tetraalkoxysilanes, specifically methoxytrichlorosilane, ethoxytrichlorosilane, and dimethoxydichlorosilane. , diethoxydichlorosilane, triethoxychlorosilane, tetramethoxysilane, tetraethoxysilane, etc., and those containing a high alkoxy group containing two or more alkoxy groups are particularly preferred.

Note that these do not necessarily need to be used alone, and a mixture thereof may be used.

Further, titanium halides that can be used include tetravalent, trivalent, and divalent halogen-containing titanium, and specifically, T
iCl,, TiBr4, Ti(OR')Cl3, Ti(
OR')2Cl2, Ti(OR')3C1, TiCl3
, TiBr3, TiC12, etc. (where R' represents an alkyl group.

), and those that do not contain a large amount of alkoxy groups are particularly preferred.

The reaction between the modified magnesium chloride, the alkoxy-containing silicon compound, and the titanium halide is usually carried out in a hydrocarbon solvent, but it can also be carried out without a solvent, and any commonly employed contact method may be used.

When carried out in a solvent, a predetermined amount of alkoxy-containing alkoxy is added directly to the reaction solution producing the modified product by the solvent method, or after dispersing the modified product in an inert solvent again when processing such as washing and separation of the reaction solid is carried out. Add silicon compound and titanium halide.

The mixed dispersion thus obtained is heated at normal pressure or under pressure.
10 at a temperature of 0 to 200°C, preferably 50 to 150°C.
The reaction is stirred for 5 minutes to 5 hours, preferably 0.5 to 3 hours.

On the other hand, in the case of a solventless reaction, mechanical mixing using a ball mill or the like may be performed at the above temperature and time.

In addition, as a mode of contact between the modified product, the alkoxy-containing silicon compound, and the titanium halide, the modified product and the alkoxy-containing silicon compound are brought into contact reaction at 60 to 100°C for 0.5 to 2 hours, and then the titanium halide is added to the system. Another embodiment of the present invention is a method of adding and carrying out a catalytic reaction under the above conditions.

The amount of alkoxy-containing silicon compound used in the above reaction is usually 0.1 to 50% based on the magnesium chloride used.
The amount is twice the molar amount, preferably 0.1 to 5 times the molar amount.

The proportion of titanium halide added is usually at least the equivalent molar amount, preferably in excess, relative to the amount of magnesium chloride used.

Specifically, the amount should be 1 to 20 times the molar amount, preferably 2 to 15 times the molar amount, especially when unreacted alcohol and free titanium compounds are present in the solution when the modified product pretreatment solution is used as is. A large excess compared to that of the halogen-containing titanium compound originally used.
It is preferable to use twice the molar amount or more as a guideline.

If the amount of titanium halide used is small, the resulting polyethylene will not have sufficient bulk specific gravity or polymerization activity.

After carrying out the above reaction, solid components are separated and washed from the reaction product.

This washing is carried out using an inert hydrocarbon solvent having 5 to 10 carbon atoms, such as pentane, hexane, cyclohexane, heptane, etc.

The washed solid product is further dispersed in an inert hydrocarbon solvent in an inert gas at an appropriate concentration and used as a catalyst component.

Note that the solid product after washing may be further treated with organoaluminum and then made into a dispersion as described above. In this case, the polymerization activity of the catalyst and the bulk specific gravity of the polyethylene to be polymerized are further increased.

The organoaluminum compound that can be used in this case may be the same as or different from the organoaluminum compound as catalyst example (B) described later.

It is sufficient that the amount used is approximately equal to the amount of supported titanium, or greater.

In the method of the present invention, the reaction product of the above-mentioned modified magnesium chloride, the above-mentioned alkoxy-containing silicon compound, and titanium halide is used as a captive component, and the organoaluminum compound is used as the (B) component (A), (B). This is carried out using a catalyst consisting of both components.

In polymerizing ethylene, a dispersion of component (A) and an organic aluminum compound as component (B) are added as catalysts to the reaction system, 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 usually 0.001 to 5 mmol/
l, and on the other hand, the ratio of component (B) to component (A) is 10 to 5
00 (molar ratio), preferably 20 to 300 (molar ratio).

In addition, the ethylene pressure in the reaction system is usually normal pressure to 100 kg/c.
m2, preferably 2 to 20 kg/cm2, the reaction temperature is usually 50 to 180°C, preferably 60 to 100°C, and the reaction time is usually 0.5 to 5 hours, preferably 1 to 3
Time.

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

The organoaluminum compound which is the component (B) of the catalyst used in the method of the present invention has the general formula R″pAIC1
3-p [in the formula, R'' represents an alkyl group having 1 to 8 carbon atoms, and p represents 1.5 to 3;

] are preferred, and typical examples thereof include trialkylaluminum compounds such as trimethylaluminum, triethylaluminum, triisoprobylaluminium, triisobutylaluminum, and trioctylaluminum, and diethylaluminium monochloride and diisoprobylaluminium. Examples include dialkylaluminum monohalides such as monochloride, diisobutylaluminum monochloride, and dioctylaluminum monochloride.

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 small amounts of α-olefins such as propylene, butene-1, hexene-1, and the like.

According to the method of the present invention as described above, although the actual nature of the carrier is unknown, an effective carrier is formed by a complex reaction among the halogen-containing tetravalent titanium compound, alcohol, and magnesium chloride in the modification step, Furthermore, as silicon and titanium are effectively supported on the modified product, high polymerization activity is exhibited and polyethylene with a high bulk density can be obtained.

Therefore, by the method of the present invention, high-quality, high-density polyethylene of high bulk specific gravity can be produced extremely efficiently and economically.

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

Example 1 (1) Preparation of catalyst Add 10 ml of anhydrous magnesium chloride to 50 ml of normal heptane.
, 5 mmol was suspended, 45.3 mmol of TiCl and 21 mmol of ethanol were added thereto, and the temperature was raised to 80°C.
A time reaction was performed.

Then Si(QC2H5), 5.2 mmol, TiCl
445 mmol was added and the reaction was carried out under reflux (98°C) for 3 hours.

After cooling, the supernatant liquid was removed by decanting.

Add 100ml of normal heptane, stir, and let stand.
The washing operation of removing the supernatant liquid was repeated three times.

Finally, 200 ml of normal heptane was added to obtain a dispersion of catalyst solid components.

The amount of titanium supported was determined by colorimetric method: 38 mg-Ti/
g-carrier.

(2) Polymerization of ethylene A 1 liter autoclave was thoroughly dried, and a slurry of 400 ml of n-hexane, 2.0 mmol of triethylaluminum, and the above catalyst solid component (A) was added in an amount equivalent to 0.01 mmol of titanium atoms under an argon atmosphere. The temperature was raised to 80°C, and then polymerization was carried out at 80°C for 1 hour while continuously supplying ethylene at a hydrogen pressure of 3 kg/cm 2 and an ethylene pressure of 5 kg/cm 2 .

Unreacted gas was removed, and the polymer was separated and dried to obtain 219 g of white polyethylene.

The polymerization activity is 456 kg per gram of titanium atom per hour, and the melt index of polyethylene is 4.2 (1
90° C., 216 kg load), and the bulk specific gravity was 0.34.

Comparative Example 1 (1) Production of catalyst 10% of anhydrous magnesium chloride in 50ml of normal heptane
．． 5 mmol was suspended, 21 mmol of ethanol was added thereto, the temperature was raised, and the reaction was carried out at 80° C. for 1 hour.

Next, 1445 mmol of TiC was added and reacted at 98°C for 3 hours.

A solid catalyst component was produced in the same manner as in Example 1(l).The amount of titanium supported at this time was 172 mg-Ti/g per carrier.

(2) Polymerization of ethylene Ethylene polymerization was carried out in the same manner as in Example 1 (2) except that the solid catalyst component prepared in (1) above was used.

As a result, 45 g of polyethylene was obtained.

The polymerization activity is 94 kg per gram of titanium atom per hour, and the melt index of polyethylene is 3.8 (19
(0°C, 2.16 kg load) The bulk specific gravity was 0.19.

Comparative Example 2 (1) Production of catalyst 10% of anhydrous magnesium chloride in 50ml of normal heptane
．． 5 mmol of TiC was suspended, 145.3 mmol of TiC and 21 mmol of ethanol were added thereto, and the temperature was raised to 80°C for 1
A time reaction was performed.

Next, 445 mmol of TiCl was added and reacted at 98°C for 3 hours.

A solid catalyst component was produced in the same manner as in Example 1 (1).

The amount of titanium supported at this time was 37 to -Ti/P on the carrier.

(2) Polymerization of ethylene Ethylene polymerization was carried out in the same manner as in Example 1 (2) except that the solid catalyst component prepared in 1) above was used.

As a result, 126 g of polyethylene was obtained.

The polymerization activity is 263 kg per gram of titanium atom per hour, and the tart index of polyethylene is 16.5 (
(190°C, 2.16 kg load), and the bulk specific gravity was 0.28.

Comparative Example 3 (1) Production of catalyst 10% of anhydrous magnesium chloride in 50ml of normal heptane
．． 5 mmol was suspended, 21 mmol of ethanol was added thereto, the temperature was raised, and the reaction was carried out at 80° C. for 1 hour.

Then 45.2 mmol of Si(OC2H5), TiC1
45 mmol of A4 was added, and the mixture was reacted at 98°C for 3 hours.

A solid catalyst component was produced in the same manner as in Example 1(l).

The amount of titanium supported at this time was 22 to 1 Ti/g to 1 carrier.

(2) Polymerization of ethylene Ethylene polymerization was carried out in the same manner as in Example 1 (2) except that the solid catalyst component prepared in (1) above was used.

As a result, 98 g of polyethylene was obtained.

The polymerization activity is 12 titanium atoms, 204 kg per hour, and the melt index of polyethylene is 2.5 (1
The bulk specific gravity (90° C., 2.16 kg load) was 0.21.

Comparative Example 4 (1) Production of catalyst 10% of anhydrous magnesium chloride in 50ml of normal heptane
．． 5 mmol was suspended, 1445 mmol of TiC, 410.5 mmol of Si(OC2H5) and 21 mmol of ethanol were added thereto, the temperature was raised, and the reaction was carried out at 98°C for 3 hours.

After cooling, the reaction solution was removed by a decanting method, and the following Example 1 (
A solid catalyst component was produced in the same manner as in 1).

The amount of titanium supported at this time was 40 to -Ti/g-carrier.

(2) Polymerization of ethylene Ethylene polymerization was carried out in the same manner as in Example 1 (2) except that the solid catalyst component prepared in (1) above was used.

As a result, 36 g of polyethylene was obtained.

The polymerization activity is 74 kg per gram of titanium atom per hour, and the tart index of polyethylene is 0.53 (1
The bulk specific gravity (90° C., 2.16 kg load) was 0.21.

Comparative Example 5 (1) Production of catalyst 10% of anhydrous magnesium chloride in 50ml of n-butane
, 5 mmol was suspended, 145.3 mmol of SiC and 21 mmol of ethanol were added thereto, and the temperature was raised to 80°C.
A time reaction was performed.

Then 45.2 mmol of Si(OC2H5), TiC
1445 mmol was added and reacted at 98°C for 3 hours.

A solid catalyst component was produced in the same manner as in Example 1 (1).

The amount of titanium supported at this time was 35 to -Ti/g-carrier.

(2) Polymerization of ethylene Ethylene polymerization was carried out in the same manner as in Example 1 (2) except that this solid catalyst component was used in an amount corresponding to 0.02 mmol as titanium atoms.

As a result, 107 g of polyethylene was obtained.

The polymerization activity is 112 kg per gram of titanium atom per hour, and the melt index of polyethylene is 2.5 (1
90° C., 2.16 kg load), and the bulk specific gravity was 0.26.

Examples 2 to 5 A solid catalyst component was produced and ethylene was polymerized in the same manner as in Example 1, except that the amounts of TiCl4 and ethanol used in the magnesium chloride modification step were changed.

The results are shown in Table 1. Example 6 (1) Preparation of catalyst Add 10 ml of anhydrous magnesium chloride to 50 ml of normal heptane.
．． 5 mmol of TiCl was suspended, 45.3 mmol of TiCl and 21 mmol of ethanol were added thereto, and the temperature was raised to 80°C for 1
A time reaction was performed.

Then, it was cooled to room temperature, the supernatant liquid was removed and washed once with 100 ml of n-heptane, and 5 ml of n-heptane was added to this.
0 ml was added to prepare a dispersion.

In this dispersion, 45.3 mmol of Si(QC2H,,),
1445 mmol of TiC was added and reacted at 98°C for 3 hours.

A solid catalyst component was produced in the same manner as in Example 1 (1).

The amount of titanium supported at this time was 97 mg-Ti/g-support.

(2) Polymerization of ethylene Ethylene polymerization was carried out in the same manner as in Example 1 (2) except that the solid catalyst component prepared in (1) above was used.

As a result, 135 g of polyethylene was obtained.

The polymerization activity is 282 kg per gram of titanium atom per hour, and the melt index of polyethylene is 0.46 (
(190° C., 2.16 kg load), and the bulk specific gravity was 0.27.

Example 7 (1) Preparation of catalyst Add 10 ml of anhydrous magnesium chloride to 50 ml of normal heptane.
．． 5 mmol was suspended, 145.3 mmol of TiC and 21 mmol of ethanol were added thereto, and the mixture was reacted at room temperature for 10 minutes.

Next, 45.3 mmol of Si(OC2H5) was added, the temperature was raised, the reaction was carried out at 80°C for 1 hour, and finally TiCl44
5 mmol was added and reacted at 98°C for 3 hours.

A solid catalyst component was produced in the same manner as in Example 1 (1).

The amount of titanium supported at this time was 8 to -Ti/g-carrier.

(2) Polymerization of ethylene Ethylene polymerization was carried out in the same manner as in Example 1 (2) except that this solid catalyst component was used in an amount corresponding to 0.005 mmol as titanium atoms.

As a result, 156 g of polyethylene was obtained.

The polymerization activity is 650 kg per gram of titanium atom per hour, and the melt index of polyethylene is 0.98 (
(190°C, 2.16 kg load), and the bulk specific gravity was 0.26.

Comparative Example 6 (1) Production of catalyst 10% of anhydrous magnesium chloride in 50ml of normal heptane
．． 5 mmol was suspended, 145.3 mmol of TiC, 45.3 mmol of Si(QC2H,), and 21 mmol of ethanol were added thereto, the temperature was raised, and the reaction was carried out at 80° C. for 1 hour.

Next, 1445 mmol of TiC was added and reacted at 98°C for 3 hours.

A solid catalyst component was produced in the same manner as in Example 1 (1).

The amount of titanium supported at this time was 44 mg/Ti/g/carrier.

(2) Polymerization of ethylene Ethylene polymerization was carried out in the same manner as in Example 1 (2) except that this solid catalyst component was used in an amount equivalent to 0.02 mmol as titanium atoms.

As a result, 95 g of polyethylene was obtained.

The polymerization activity is 99 kg per gram of titanium atom per hour, and the Mel 1 index of polyethylene is 0.84 (
(190°C, 2.16 kg load), and the bulk specific gravity was 0.23.

Comparative Example 7 (1) Production of catalyst 10% of anhydrous magnesium chloride in 50ml of normal heptane
．． 5 mmol of TiC was suspended, 145.3 mmol of TiC and 21 mmol of ethanol were added thereto, and the temperature was raised to 80°C.
A time reaction was performed.

Next, 45.2 mmol of Si(QC2H5) was added to
After reacting at 0°C for 1 hour, washing with n-heptane, 1445 mmol of TiC was added to the redispersion, and the mixture was incubated at 98°C for 3 hours.
Allowed time to react.

A solid catalyst component was produced in the same manner as in Example 1 (■).

The amount of titanium supported at this time was 13m9-Ti/g of carrier.

(2) Polymerization of ethylene Ethylene polymerization was carried out in the same manner as in Example 1 (2) except that the solid catalyst component prepared in (1) above was used.

As a result, 90 g of polyethylene was obtained.

The polymerization activity is 11 titanium atoms, 188 kg per hour, and the tart index of polyethylene is 5.8 (1
90° C., 2.16 kg load), and the bulk specific gravity was 0.26.

Examples 8 and 9 A solid catalyst component was produced and ethylene was polymerized in the same manner as in Example 1, except that isopropanol or n-butanol was used in place of ethanol.

The results are shown in Table 2. Example 10 (1) Production of catalyst C12Si(OC2H5
) Example 1 (1) except that 25.3 mmol was used.
A solid catalyst component was produced in the same manner as above.

The amount of titanium supported at this time was 13 mg-Ti/g per carrier.

(2) Polymerization of ethylene Ethylene polymerization was carried out in the same manner as in Example 1 (2) except that the solid catalyst component prepared in (1) above was used.

As a result, 183 g of polyethylene was obtained.

The polymerization activity is 423 kg per gram of titanium atom per hour, and the melt index of polyethylene is 18.3 (
(190°C, 2.16 load), and the bulk specific gravity was 0.29.

Comparative Example 8 (1) Production of catalyst A solid catalyst component was produced in the same manner as in Example 1 (■) except that 145.3 mmol of SiC was used in place of Si(OC2H5)4.

The amount of titanium supported at this time was 9 mg-Ti/g per carrier.

(2) Polymerization of ethylene Ethylene polymerization was carried out in the same manner as in Example 1 (2) except that this solid catalyst component was used in an amount corresponding to 0.02 mmol as titanium atoms.

As a result, 138 g of polyethylene was obtained.

The polymerization activity is 147 kg per gram of titanium atom per hour, and the melt index of polyethylene is 1.3 (1
90° C., 2.16 kg load), and the bulk specific gravity was 0.17.

Claims (1)

[Claims] 1. A method for producing polyethylene using a catalyst containing (A) a reaction product of a magnesium compound and a titanium halide and (B) an organoaluminum compound, wherein magnesium chloride is used as the component (A). is reacted in contact with a halogen-containing tetravalent titanium compound of 0.1 to 2 times the molar amount and an alcohol of 0.1 times the molar amount or more, and then the produced solid substance is reacted with a titanium halide in the presence of an alkoxy-containing silicon compound. A method for producing polyethylene, characterized by using a solid product obtained by. 2 The halogen-containing tetravalent titanium compound has the general formula XnTi
(OR)4-n (wherein X is a halogen atom, R is an alkyl group having 1 to 4 carbon atoms, and n is an integer of 1 to 4). The method according to claim 1. 3 The method according to claim 1, wherein the halogen-containing tetravalent titanium compound is titanium tetrachloride. 4 The alkoxy-containing silicon compound has the general formula XmSi(O
R) 4-m (in the formula, X is a halogen atom, R is a carbon number of 1 to 4
m represents an integer of 0 to 3. ] The method according to claim 1, wherein the compound is a compound represented by: 5. The method according to claim 1, wherein the alkoxy-containing silicon compound is a silicon compound containing two or more alkoxy groups.