JP2001288203A - Preparation method of linear low density polyethylene composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a preparation method of linear low density polyethylene (LLDPE) which does not produce sheet-like material in the reactor and which yields an LLDPE with a narrow composition distribution with a high polymerization activity. SOLUTION: The preparation method of a linear low density polyethylene composition comprises using two gas-phase fluidized bed reactors and copolymerizing ethylene and an α-olefin in the presence of a prepolymerized metallocene-based supported catalyst to prepare a composition, wherein a mixture of a polymerizable monomer and a saturated aliphatic hydrocarbon is introduced into the fluidized beds as a two- phase mixture of gas and liquid and a high molecular weight polyethylene is prepared in the first stage and a low molecular weight polyethylene is prepared in the second stage under conditions where the polymerization temperatures at the first stage and second stage (T1 and T2, respectively) satisfy the relationship: T1<=T2<T1+30 and the partial ethylene pressures at the first stage and second stage (P1 and P2, respectively) satisfy the relationship: P1<=P2<P1+1.0 and the contents of the saturated aliphatic hydrocarbon in the mixed gases at the first stage and second stage are kept at 1-20 mol%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a linear low-density polyethylene composition, and more particularly to a method for producing high-molecular-weight polyethylene using two gas-phase fluidized-bed reactors connected in series. The present invention relates to a method for producing a linear low-density polyethylene composition comprising low-molecular-weight polyethylene.

[0002]

BACKGROUND OF THE INVENTION Linear low density polyethylene (LLDPE) which is a copolymer of ethylene and α-olefin
Has excellent properties such as excellent heat sealability, flexibility and toughness, excellent water resistance, moisture resistance, chemical resistance, and low cost. It is widely used as a material for applications.

[0003] LLDPE is usually produced by copolymerizing ethylene and an α-olefin under a low pressure in the presence of a Ziegler catalyst. Examples of the polymerization method include liquid phase polymerization methods such as solution polymerization and slurry polymerization. There is a gas phase polymerization method. When LLDPE is produced by the gas phase polymerization method, the polymer is obtained in the form of particles, so that the production process can be simplified as compared with the liquid phase polymerization method which requires steps such as particle precipitation and particle separation from the polymerization solution. It is advantageous.

When an olefin is subjected to gas-phase polymerization in the presence of a solid catalyst using a gas-phase fluidized-bed reactor, a polymer mass or a sheet-like substance is generated in the fluidized bed, or the fluidity of the polymer particles is reduced. As a result, the mixing state in the fluidized bed becomes non-uniform, and it may not be possible to stably operate continuously for a long period of time. As a method for solving such a problem, there are a method of supporting a surfactant on a solid catalyst, a method of introducing a surfactant into a reactor, and the like. However, in these methods, polymerization activity may be reduced. .

[0005] Further, as for LLDPE, a film having excellent composition and the like can be obtained if the composition distribution is narrow. The present inventors have studied a method for producing LLDPE by a gas phase polymerization method under such circumstances. As a result, ethylene and a carbon atom number of 3 to 10α- were obtained using two gas phase fluidized bed reactors. When copolymerizing an olefin, a mixture containing a polymerized monomer and a saturated aliphatic hydrocarbon having 2 to 10 carbon atoms is introduced into the fluidized bed as a two-phase mixture of a gas and a liquid. Specific ethylene and
When an α-olefin copolymer is produced, LLDPE having a narrow composition distribution can be obtained without generating polymer lumps, sheet-like substances, etc. in the reactor, and such LLD
The inventors have found that PE can be obtained with high activity, and have completed the present invention.

[0006]

An object of the present invention is to provide an LL having a narrow composition distribution without generating a polymer lump or a sheet-like material in a fluidized bed.
It is an object of the present invention to provide a method for producing a linear low-density polyethylene composition in which DPE can be obtained with high polymerization activity.

[0007]

SUMMARY OF THE INVENTION A method for producing a linear low-density polyethylene composition according to the present invention comprises the use of two gas-phase fluidized-bed reactors connected in series to form a metallocene-based supported catalyst in which an olefin is prepolymerized. In the presence, the solid particles containing the catalyst are maintained in a fluidized state by the gas flow of the fluidizing gas flowing in the fluidized bed, and ethylene and α- having 3 to 10 carbon atoms are kept in the fluidized bed.
When producing a linear low-density polyethylene composition by copolymerizing an olefin, a mixture containing a polymerized monomer and a saturated aliphatic hydrocarbon having 2 to 10 carbon atoms is subjected to the above-mentioned fluidization as a two-phase mixture of a gas and a liquid. The polymerization temperature of the first stage is set to T ₁ (° C.), and the polymerization temperature of the second stage is set to T ₁ (° C.).
₂ (° C.), T ₁ and T ₂ satisfy T ₁ ≦ T ₂ <
When the relationship represented by T ₁ +30 is satisfied and the ethylene partial pressure in the first-stage reactor is P ₁ (MPa) and the ethylene partial pressure in the second-stage reactor is P ₂ (MPa), satisfy the relationship with the P ₁ and P ₂ are represented by P ₁ ≦ P ₂ <P ₁ +1.0, 1.0 the content of saturated aliphatic hydrocarbons fluidizing gas of the first stage reactor -20 mol%, the flow index of the first-stage reactor was set to be in the range of 1.0 to 20 mol% of the saturated aliphatic hydrocarbon in the fluidized gas of the second-stage reactor. It is in the range of 0.01 to 50 g / 10 min and the density is 0.860 to 0.940 g / cm ³
And a melt index of 5 to 3000 g / 10 10 in the second stage reactor.
Min and a density of 0.900 to 0.975 g /
It is characterized in that a low molecular weight polyethylene in the range of cm ³ is produced, and a composition in which the weight ratio of the high molecular weight polyethylene to the low molecular weight polyethylene is in the range of 30:70 to 80:20.

The linear low-density polyethylene composition obtained by the above method has a melt index of 0.02 to 0.02.
It is in the range of 3.5 g / 10 minutes and the melt flow ratio is 30 to
In the range of 150, the density is 0.910 to 0.960 g
/ Cm ³ is preferably in the range.

[0009]

DETAILED DESCRIPTION OF THE INVENTION Hereinafter, the method for producing the linear low-density polyethylene composition according to the present invention will be specifically described.

In the present invention, ethylene and an α-olefin having 3 to 10 carbon atoms (hereinafter referred to as “C”) are used in the presence of a prepolymerized supported metallocene catalyst using two gas-phase fluidized-bed reactors connected in series. , And these are sometimes referred to as “polymerized monomers” when polymerized with a polymerized monomer and a saturated aliphatic hydrocarbon having 2 to 10 carbon atoms (hereinafter sometimes simply referred to as “saturated aliphatic hydrocarbon”). ) Is introduced into a fluidized bed as a two-phase mixture of gas and liquid, and a first-stage reactor produces high-molecular-weight polyethylene, and a second-stage reactor produces low-molecular-weight polyethylene. Manufactures linear low density polyethylene.

First, an example of a multistage gas-phase polymerization apparatus used in the present invention will be described with reference to FIG. In the multistage gas phase polymerization apparatus, for example, as shown in FIG. 1, a first fluidized bed reactor 11 and a second fluidized bed reactor 21 are connected in series.

That is, in the first fluidized bed reactor 11,
A prepolymerized metallocene-based supported catalyst (solid catalyst) is supplied from a supply line 15, and a mixture (fluidized gas) containing a polymerization monomer and a saturated aliphatic hydrocarbon is supplied from a supply line 12 to a first catalyst via a blower 13. Is supplied from the bottom of the fluidized bed reactor 11. The supplied fluidized gas is blown into the fluidized bed 18 through a dispersion plate 17 formed of a perforated plate or the like disposed near the bottom of the first fluidized bed reactor 11, and is injected from the top of the fluidized bed reactor 11. After being discharged, it passes through the fluidized bed reactor 11. The solid particles (solid catalyst and produced polymer) are kept in a fluidized state by the gas flow of the gas passing through the fluidized bed reactor 11, and the fluidized bed 18 is formed.

The produced polymer particles are continuously or intermittently extracted, and are separated into solid-gas separation vessels 31 and 3.
The solid-gas separation is performed at 2. At this time, the valves 33 and 34 are
Opening / closing is controlled as appropriate. The polymer particles thus extracted are discharged to the transfer line 25 by the operation of the valve 35, and are sent to the second fluidized bed reactor 21 through the transfer line 25.

The flow rate of unreacted polymerized monomers, saturated aliphatic hydrocarbons, and the like that have passed through the fluidized bed 18 is reduced in a deceleration region 19 provided above the first fluidized bed reactor 11. Thus, the gas is discharged to the outside of the first fluidized bed reactor 11 via a gas outlet provided at the upper part of the first fluidized bed reactor 11.

Unreacted polymerized monomers and saturated aliphatic hydrocarbons discharged from the first fluidized bed reactor 11 pass through a circulation line 16 and pass through a heat exchanger (cooling device) 14.
, And joins the supply line 12, and the blower 13
Thus, the fluid is continuously supplied again into the fluidized bed 18 in the first fluidized bed reactor 11. In the heat exchanger 14, the circulating gas is cooled to a temperature lower than the dew point of the gas, and the obtained two-phase mixture of gas and liquid is fluidized bed reactor 1
1 is introduced. When circulating the circulating gas to the first fluidized bed reactor 11, a part of the circulating gas may be purged from an arbitrary position in the circulating line 16.

On the other hand, the second fluidized bed reactor 21 has the first
The polymer particles extracted from the extraction line 30 from the extraction line 30 through the solid-gas separation vessels 31 and 32 from the fluidized bed reactor 11 are sent through the transport line 25,
By this transfer line 25, new olefins and saturated aliphatic hydrocarbons are supplied from the supply line 22 to the blower 23.
And a fluidizing gas comprising a mixture containing a polymerization monomer, a saturated aliphatic hydrocarbon, etc., is supplied from a supply line 22 through a blower 23 to the bottom of the second fluidized bed reactor 21. It is supplied from.

The transfer line 25 branches off from the supply line 22, and the other end is connected above the second fluidized bed reactor 21. The polymerization monomer and the saturated aliphatic hydrocarbon sent from the supply line 22 are connected to the transfer line 25. Is increased by a pressure increasing means such as a centrifugal blower 41,
The polymer particles withdrawn from the fluidized bed reactor 11 of the second fluidized bed reactor 21
Is to be introduced.

The fluidized gas supplied from the bottom of the second fluidized bed reactor 21 flows through a dispersion plate 27 such as a perforated plate disposed near the bottom of the second fluidized bed reactor 21. It is blown into the bed 28 and discharged from the upper part of the fluidized bed reactor 21 to pass through the inside of the fluidized bed reactor 21.
The solid particles (the polymer particles and the produced polymer) are kept in a fluidized state by the gas flow of the gas passing through the fluidized bed reactor 21 to form the fluidized bed 28. At this time, a copolymerization reaction is performed in the fluidized bed 28.

The polymer particles obtained in the second fluidized bed reactor 21 are continuously or intermittently withdrawn from the line 40. The unreacted polymerized monomer, saturated aliphatic hydrocarbon, and the like that have passed through the fluidized bed 28 have a reduced flow velocity in a deceleration region 29 provided above the second fluidized bed reactor 21,
The gas is discharged to the outside of the second fluidized bed reactor 21 via a gas outlet provided at the upper part of the second fluidized bed reactor 21.

The unreacted polymerized monomers, saturated aliphatic hydrocarbons, etc. discharged from the second fluidized bed reactor 21 are:
After being cooled by the heat exchanger (cooling device) 24 through the circulation line 26, it is combined with the supply line 22, and is continuously supplied again into the fluidized bed 28 in the second fluidized bed reactor 21 by the blower 23. It has become so. In the heat exchanger 24, the circulating gas is cooled to a temperature lower than the dew point of the gas,
The resulting two-phase mixture of gas and liquid is introduced into the fluidized bed reactor 21. The circulating gas is supplied to the second fluidized bed reactor 21.
When a part of the circulating gas is circulated to the circulation line 26,
May be purged from any location.

As described above, in the first fluidized bed reactor 11, the fluidized gas is circulated at a flow rate capable of maintaining the fluidized bed 18 in a fluidized state. The fluidizing gas is circulated at such a flow rate that the fluidized bed 28 can be maintained in a fluidized state.

Specifically, supply lines 12 and 22
The amount of fluidizing gas introduced from the bottom of the reactor
The minimum fluidization speed of the moving bed_mfAnd about 3U_mf~ 5
0U _mfDegree, preferably about 5U_mf~ 30U_mfAbout flow rate
It is desirable that The fluidized bed is mechanically stirred
Can also be used, for example, squid-type stirrer, screw-type stirrer
Using various types of stirrers such as mixers and ribbon-type stirrers.
Can be stirred.

In the present invention, ethylene supplied to the fluidized bed reactor and α-olefin having 3 to 10 carbon atoms are copolymerized in the fluidized bed using the above-described multistage gas phase polymerization apparatus. The first-stage reactor produces high-molecular-weight polyethylene, the second-stage reactor produces low-molecular-weight polyethylene, and the second-stage reactor produces the copolymer produced in the first-stage reactor. It copolymerizes in the presence to produce linear low density polyethylene.

Specific examples of the α-olefin having 3 to 10 carbon atoms include propylene, 1-butene, 1-pentene, 1-pentene,
Hexene, 4-methyl-1-pentene, 1-octene, 1-decene and the like. Among them, the number of carbon atoms is 5
To 8 are particularly preferably used. These α-olefins having 3 to 10 carbon atoms can be used alone or in combination of two or more.

The ratio of ethylene to the α-olefin having 3 to 10 carbon atoms supplied to the fluidized bed reactor varies depending on the linear low density polyethylene composition to be finally obtained. In a fluidized bed reactor for producing polyethylene, olefin is usually added in an amount of 0.1 mol per mol of ethylene.
In a fluidized bed reactor for producing low molecular weight polyethylene, which is supplied in an amount of from 0.01 to 0.4 mol, preferably from 0.02 to 0.35 mol, usually 0.005 to 0.6 mol of olefin per mol of ethylene is used. Mol, preferably 0.01-0.4
It is supplied in an amount of 2 mol.

Hydrogen can be supplied to the fluidized bed reactor as required. In this case, in a fluidized bed reactor for producing high molecular weight polyethylene, olefin is usually used in an amount of 0.001 to 0 mol per mol of ethylene. 0.3 mol, preferably 0.017 to 0.18 mol, in a fluidized bed reactor for producing low molecular weight polyethylene, usually 0.01 to 3 mol, preferably 0 to 0 mol of olefin per mol of ethylene. It is supplied in an amount of from 0.5 to 2.2 mol.

In the present invention, ethylene and C 3
Polyenes and the like may be copolymerized with α-olefin of 10 to 10 if necessary, for example, conjugated dienes such as butadiene and isoprene; 1,4-hexadiene, dicyclopentadiene, 5-vinyl-2-norbornene and the like. Can be copolymerized.

In the present invention, the copolymerization is carried out while introducing a mixture containing a polymerization monomer and a saturated aliphatic hydrocarbon having 2 to 10 carbon atoms into the fluidized bed as a two-phase mixture of gas and liquid. Specifically, it contains unreacted polymerized monomers, saturated aliphatic hydrocarbons, inert gas such as nitrogen, hydrogen as a molecular weight regulator, etc., which are discharged from a gas discharge port provided at the upper part of the fluidized bed reactor. The circulating gas is cooled using a cooling device to a temperature below the dew point of the gas and the resulting two-phase mixture is introduced into the reactor. The dew point is a temperature at which a liquid condensate starts to be generated in a gas stream.

The polymerization is carried out under such conditions that at least a part of the liquid phase in the above two-phase mixture is volatilized in the fluidized bed and a part of the liquid phase passes through the fluidized bed. Can also.

Examples of the saturated aliphatic hydrocarbon having 2 to 10 carbon atoms include, for example, ethane, propane, n-butane, i-butane, n-pentane, i-pentane, hexane,
Heptane, octane, nonane, decane, 2,2-dimethylpropane, 2,2-dimethylbutane, 2,3-dimethylbutane, 2,
2,3-trimethylbutane, 2-methylpentane, 3-methylpentane, 2,2-dimethylpentane, 3,3-dimethylpentane, 2,3-dimethylpentane, 2,4-dimethylpentane, 2-
Examples include methylhexane, 3-methylhexane, 4-methylhexane, 2,3-dimethylhexane, cyclopentane, cyclohexane, methylcyclopentane, dimethylcyclopentane, and the like. These saturated aliphatic hydrocarbons
One type may be used alone, or two or more types may be used in combination.

The above-mentioned saturated aliphatic hydrocarbon is a non-polymerizable hydrocarbon, and once supplied into the fluidized-bed reactor, does not deplete due to polymerization, and is discharged from the fluidized-bed reactor. The saturated aliphatic hydrocarbons contained therein are circulated to the fluidized bed reactor via a circulation line.

The content of the saturated aliphatic hydrocarbon in the mixed gas in the fluidized bed was 1.0% in the mixed gas in the first fluidized bed.
1.0 to 20 mol%, preferably 5.0 to 10 mol%, in the mixed gas in the fluidized bed of the second stage.
It is prepared so as to be contained in an amount of ２０20 mol%, preferably 5.0 to 10 mol%. The mixed gas contains a polymerization monomer, a saturated aliphatic hydrocarbon, an inert gas such as nitrogen, hydrogen as a molecular weight regulator, and the like.

The preferred range of the amount of the saturated aliphatic hydrocarbon contained in the mixed gas generally varies depending on the number of carbon atoms, and is preferably a saturated aliphatic hydrocarbon having 2 carbon atoms (ethane).
Is in an amount of 10 to 20 mol%, preferably 15 to 20 mol%, and the saturated aliphatic hydrocarbon having 3 carbon atoms (propane) is in an amount of 5 to 20 mol%, preferably 10 to 20 mol%.
The saturated aliphatic hydrocarbon having 4 carbon atoms (n-butane, i-butane) is 3 to 20 mol%, preferably 8 to 20 mol%, and the saturated aliphatic hydrocarbon having 5 carbon atoms (n-butane) is used. Pentane,
i-pentane) in an amount of 2 to 20 mol%, preferably 4 to 20 mol%, and a saturated aliphatic hydrocarbon having 6 carbon atoms (n-hexane, 2-methylpentane, 3-methylpentane, cyclohexane) 1.5 to 20 mol%, preferably 2.5 to
In an amount of 15 mol%, a saturated aliphatic hydrocarbon having 7 carbon atoms (n-heptane, 2-methylhexane, 3-methylhexane,
4-methylhexane, methylcyclohexane)
In an amount of 15 mol%, preferably 2.0 to 10 mol%, a saturated aliphatic hydrocarbon having 8 to 10 carbon atoms is 0.8 to 10 mol%.
It is desirable that it be contained in the mixed gas in an amount of mol%, preferably 1.5 to 7 mol%.

In the present invention, the polymerization temperature of the first stage is set to T
_{When 1} (° C.) and the polymerization temperature of the second stage are T ₂ (° C.), T ₁ and T ₂ satisfy T ₁ ≦ T ₂ <T ₁ +30, preferably T ₁ ≦ T ₂ <T ₁ +15. The copolymerization is carried out under the conditions satisfying the relationship shown by.

The polymerization temperature varies depending on the type and ratio of the olefin to be copolymerized, the ratio of the saturated aliphatic hydrocarbon, the fluidized state of the fluidized bed, and the like. Specifically, the polymerization temperature of the first stage reactor ( T ₁ ) is a temperature equal to or higher than the dew point of the mixed gas in the fluidized bed, and is usually 20 to 130 ° C., preferably 50 ° C.
To 120 ° C, more preferably 70 to 110 ° C.

When the partial pressure of ethylene in the first-stage reactor is P ₁ (MPa) and the partial pressure of ethylene in the second-stage reactor is P ₂ (MPa), P ₁ and P 2 _The copolymerization is carried out under the condition that 2 satisfies the relationship of P ₁ ≦ P ₂ <P ₁ +1.0, preferably P ₁ ≦ <P ₂ <P ₁ +0.5.

The partial pressure of ethylene is determined by the polymerization pressure (MP
a) x Concentration of ethylene in mixed gas in polymerization vessel (mol%)
It is represented by Ethylene partial pressure of the first stage reactor (P ₁ )
Is 0.02 to 9.0 MPa, preferably 0.2 to 5.0 MPa.
The range is 0 MPa.

The polymerization pressure varies depending on the type and ratio of the olefin to be copolymerized, the ratio of the saturated aliphatic hydrocarbon, the fluidized state of the fluidized bed, and the like. Pressure is usually 0.098 to 9.8MP
a, preferably in the range of 0.19 to 3.9 MPa,
The polymerization pressure in the second stage reactor is usually from 0.098 to 9.8.
Mpa, preferably in the range of 0.19 to 3.9 MPa.

The copolymerization can be carried out in the presence of a molecular weight regulator such as hydrogen, if necessary. The molecular weight regulator such as hydrogen is supplied from an arbitrary place in the fluidized bed reactor, for example, from a supply line. be able to.

In the present invention, the molecular weight of the high molecular weight polyethylene and the low molecular weight polyethylene can be adjusted by changing the polymerization conditions such as the polymerization temperature, or by controlling the amount of hydrogen (molecular weight regulator) used. It can also be adjusted.

In the present invention, in the first-stage reactor, the flow index is 0.01 to 50 g / 10 minutes, preferably 0.1 to 50 g / 10 minutes.
In the range of 2 to 12 g / 10 min and a density of at least 0.860 g / cm ³ , preferably 0.860 to 0.9
40 g / cm ³ , more preferably 0.890 to 0.94
A high-molecular-weight polyethylene in the range of 0 g / cm ³ was produced, and the melt index was 5 to 3 in the second stage reactor.
000 g / 10 min, preferably in the range of 1-1000 g / 10 min, with a density of at least 0.900 g / cm ³ ,
A low molecular weight polyethylene is produced, preferably in the range of 0.900 to 0.975 g / cm ³ , more preferably in the range of 0.910 to 0.975 g / cm ³ . At this time, in the second stage reactor, the copolymerization is carried out in the presence of the high molecular weight polyethylene produced in the first stage.

The high molecular weight polyethylene generally has a molecular weight in the range of about 135,000 to about 445,000,
Melt flow ratios are usually in the range of about 12 to about 70, preferably about 14 to about 45. The low molecular weight polyethylene generally has a molecular weight of about 15,800 to about 35,000.
And the melt flow ratio is in the range of about 12 to about 70, preferably about 14 to about 45.

The melt index is based on ASTM D
-1238, 190 ° C. and 2.1 according to condition E
Measured at 6 kg, reported as g / 10 min. The flow index is measured at 190 ° C. and 10 times the weight used to measure the melt index, according to ASTM D-1238, Condition F, and is reported as g / 10 min. Melt flow ratio is the ratio of flow index to melt index.

The linear low density polyethylene composition produced by the method of the present invention has a weight ratio of high molecular weight polyethylene to low molecular weight polyethylene of from 30:70 to 80:20,
Preferably it is in the range of 40:60 to 60:40.

The linear low-density polyethylene composition has a melt index in the range of 0.02 to 3.5 g / 10 min, preferably 0.04 to 2.0 g / 10 min, and has a density of:
0.910 to 0.960 g / cm ³ , preferably 0.920 g / cm ³
It is desirably within the range of 0.950 g / cm ³ .
The linear low-density polyethylene composition has a molecular weight usually in the range of about 90,000 to about 450,000, and a melt flow ratio of usually about 30 to about 150, preferably about 35 to about 145. In range.

This linear low-density polyethylene composition comprises:
For example, a repeating unit derived from ethylene is 87.0-9.
In a quantity of 8.0 mol%, preferably 90.0 to 97.0 mol%, 13.0 to 2.0 mol%, preferably 10.0 to 2.0 mol% of a repeating unit derived from an olefin having 3 to 10 carbon atoms. 3.
It is contained in an amount of 0 mol%.

Further, the linear low-density polyethylene composition comprises:
As long as the object of the present invention is not impaired, the content of the repeating unit derived from the above-mentioned polyenes is 10% by weight or less, preferably 5% by weight or less, particularly preferably 3% by weight.
It may be contained in the following amounts.

In the present invention, a metallocene-based supported catalyst obtained by prepolymerizing the above copolymer (hereinafter referred to as “prepolymerized catalyst”)
There is that. ) In the presence of Specifically, the metallocene-based supported catalyst preferably used in the present invention includes, for example, a metallocene compound (A) of a transition metal selected from Group 4 of the periodic table, an organic aluminum oxy compound (B-1), and an organic aluminum compound (B). B-2) and a compound (B) which reacts with the metallocene compound (A) to form an ion pair
And at least one compound (B) selected from -3).

The transition metal metallocene compound (A) selected from the fourth periodic table is specifically represented by the following formula (i). MLx (i) wherein M is a transition metal atom selected from Zr, Ti and Hf.

L is a ligand coordinating to the transition metal atom, and at least one L is a ligand having a cyclopentadienyl skeleton, and L other than a ligand having a cyclopentadienyl skeleton. Is a hydrogen atom, a halogen atom, a hydrocarbon group having 1 to 12 carbon atoms, an alkoxy group, an aryloxy group, a trialkylsilyl group, or an SO ₃ R group (where R may have a substituent such as halogen) (A good hydrocarbon group having 1 to 8 carbon atoms).

X is a number satisfying the valence of the transition metal atom. As the ligand having a cyclopentadienyl skeleton, for example, a cyclopentadienyl group, a methylcyclopentadienyl group, a dimethylcyclopentadienyl group, a trimethylcyclopentadienyl group, a tetramethylcyclopentadienyl group, Pentamethylcyclopentadienyl group, ethylcyclopentadienyl group, methylethylcyclopentadienyl group, propylcyclopentadienyl group, methylpropylcyclopentadienyl group, butylcyclopentadienyl group, methylbutylcyclopentadiene An alkyl-substituted cyclopentadienyl group such as an enyl group and a hexylcyclopentadienyl group or an indenyl group,
Examples thereof include a 4,5,6,7-tetrahydroindenyl group and a fluorenyl group. These groups may be substituted with a halogen atom, a trialkylsilyl group or the like.

Among these, an alkyl-substituted cyclopentadienyl group is particularly preferred. Specifically, as the ligand other than the ligand having a cyclopentadienyl skeleton, examples of the halogen include fluorine, chlorine, bromine, and iodine.As the hydrocarbon group having 1 to 12 carbon atoms, Alkyl groups such as methyl group, ethyl group, propyl group, isopropyl group and butyl group; cycloalkyl groups such as cyclopentyl group and cyclohexyl group; aryl groups such as phenyl group and tolyl group; aralkyl groups such as benzyl group and neophyl group Examples of the alkoxy group include a methoxy group, an ethoxy group, and a butoxy group. Examples of the aryloxy group include a phenoxy group.
Examples of the O ₃ R group include a p-toluenesulfonato group, a methanesulfonato group, and a trifluoromethanesulfonato group.

When the compound represented by the above general formula (i) contains two or more groups having a cyclopentadienyl skeleton, two of the groups having a cyclopentadienyl skeleton are ethylene, propylene Alkylene groups such as,
It may be bonded via a substituted alkylene group such as isopropylidene or diphenylmethylene, or a substituted silylene group such as a silylene group or a dimethylsilylene group, a diphenylsilylene group, or a methylphenylsilylene group.

The metallocene compound containing a ligand having a cyclopentadienyl skeleton, for example, when the valence of the transition metal atom is 4, is more specifically represented by the following formula (ii).

R ² _k R ³ _l R ⁴ _m R ⁵ _nM (ii) wherein M is the above-mentioned transition metal, R ² is a group having a cyclopentadienyl skeleton (ligand), R ³ , R ⁴ and R ⁵ are a group having a cyclopentadienyl skeleton or another group as described above, k is an integer of 1 or more;
k + 1 + m + n = 4.

In the present invention, the above formula R ² _k R ³ _l R ⁴ _m R ⁵ _n
In M, a metallocene compound in which at least two of R ² , R ³ , R ⁴ and R ⁵ , for example, R ² and R ³ are groups (ligands) having a cyclopentadienyl skeleton is preferably used. These groups having a cyclopentadienyl skeleton may be bonded via an alkylene group, a substituted alkylene group, a silylene group, a substituted silylene group, or the like.

The metallocene compounds as described above include:
Specifically, when M is zirconium, bis (cyclopentadienyl) zirconium dichloride, bis (cyclopentadienyl) zirconium dibromide, bis (cyclopentadienyl) methylzirconium monochloride,
Bis (cyclopentadienyl) ethyl zirconium monochloride, bis (cyclopentadienyl) cyclohexyl zirconium monochloride, bis (cyclopentadienyl) phenyl zirconium monochloride, bis (cyclopentadienyl) benzyl zirconium monochloride, bis ( (Cyclopentadienyl) zirconium monochloride monohydride, bis (cyclopentadienyl) methyl zirconium monohydride, bis (cyclopentadienyl) dimethyl zirconium, bis (cyclopentadienyl) diphenylzirconium, bis (cyclopentadienyl) Dibenzyl zirconium, bis (cyclopentadienyl) zirconium methoxychloride, bis (cyclopentadienyl) zirconium ethoxycyclolide, bis (cyclohexyl) (Pentadienyl) zirconium bis (methanesulfonato), bis (cyclopentadienyl) zirconium bis (p-toluenesulfonato), bis (cyclopentadienyl) zirconium bis (trifluoromethanesulfonato), bis (methylcyclopentadienyl) ) Zirconium dichloride, bis (dimethylcyclopentadienyl) zirconium dichloride, bis (dimethylcyclopentadienyl) zirconium ethoxycyclolide, bis (dimethylcyclopentadienyl) zirconium bis (trifluoromethanesulfonato), bis (ethylcyclopentadiene) Enyl) zirconium dichloride, bis (methylethylcyclopentadienyl) zirconium dichloride, bis (propylcyclopentadienyl) zirconium dichloride, bis (methyl Propylcyclopentadienyl) zirconium dichloride, bis (butylcyclopentadienyl) zirconium dichloride, bis (methylbutylcyclopentadienyl) zirconium dichloride, bis (methylbutylcyclopentadienyl) zirconium bis (methanesulfonate), bis (Trimethylcyclopentadienyl) zirconium dichloride, bis (tetramethylcyclopentadienyl) zirconium dichloride, bis (pentamethylcyclopentadienyl) zirconium dichloride, bis (hexylcyclopentadienyl) zirconium dichloride, bis (trimethylsilylcyclopenta Dienyl) zirconium dichloride, bis (indenyl) zirconium dichloride, bis (indenyl) zirconium dibromide, bis (in Nil) zirconium bis (p-toluenesulfonato), bis (4,5,6,7-tetrahydroindenyl) zirconium dichloride, bis (fluorenyl) zirconium dichloride, ethylenebis (indenyl) zirconium dichloride, ethylenebis (indenyl) zirconium Dibromide, ethylene bis (indenyl) dimethyl zirconium, ethylene bis (indenyl) diphenyl zirconium, ethylene bis (indenyl) methyl zirconium monochloride, ethylene bis (indenyl) zirconium bis (methanesulfonato), ethylene bis (indenyl) zirconium bis ( p-toluenesulfonato), ethylenebis (indenyl) zirconiumbis (trifluoromethanesulfonate), ethylenebis (4,
5,6,7-tetrahydroindenyl) zirconium dichloride, isopropylidene (cyclopentadienyl-fluorenyl) zirconium dichloride, isopropylidene (cyclopentadienyl-methylcyclopentadienyl) zirconium dichloride, dimethylsilylenebis (cyclopentadiene) Enyl) zirconium dichloride, dimethylsilylenebis (methylcyclopentadienyl) zirconium dichloride, dimethylsilylenebis (dimethylcyclopentadienyl) zirconium dichloride, dimethylsilylenebis (trimethylcyclopentadienyl) zirconium dichloride, dimethylsilylenebis (indenyl) Zirconium dichloride, dimethylsilylenebis (2-methylindenyl) zirconium dichloride, dimethylsilylenebis (2-methyl , 4-isopropylindenyl) zirconium dichloride, dimethylsilylenebis (2,4,7-trimethylindenyl) zirconium dichloride, dimethylsilylenebis (indenyl) zirconiumbis (trifluoromethanesulfonato), dimethylsilylenebis (4,5, 6,7-tetrahydroindenyl) zirconium dichloride, dimethylsilylene (cyclopentadienyl-fluorenyl) zirconium dichloride,
Diphenylsilylenebis (indenyl) zirconium dichloride, diphenylsilylenebis (2-methyl, 4-isopropylindenyl) zirconium dichloride, diphenylsilylenebis (2,4,7-trimethylindenyl) zirconium dichloride, methylphenylsilylenebis (indenyl) Zirconium dichloride and the like can be mentioned.

In the above examples, the disubstituted cyclopentadienyl ring includes 1,2- and 1,3-substituted ones, and the tri-substituted one is 1,2,3- and 1,2,4-substituted. Including the body. Alkyl groups such as propyl and butyl are n-, i-, sec-, tert-
And isomers.

Further, in the above-mentioned zirconium compounds, compounds in which zirconium is replaced by titanium or hafnium can also be mentioned. In the present invention, as the metallocene compound (A), a zirconocene compound having at least two ligands having a cyclopentadienyl skeleton is preferably used, and a zirconocene having a ligand having two cyclopentadienyl skeletons is preferably used. Compounds are particularly preferably used.

These metallocene compounds (A) can be used alone or in combination of two or more. The organoaluminum oxy compound (B-1) used in the present invention may be a conventionally known benzene-soluble aluminoxane, or a benzene-insoluble organoaluminum oxy as disclosed in JP-A-2-276807. It may be a compound.

The aluminoxane as described above can be produced, for example, by the following method. (1) Compounds containing water of adsorption or salts containing water of crystallization, such as magnesium chloride hydrate, copper sulfate hydrate,
A method in which an organoaluminum compound such as trialkylaluminum is added to a hydrocarbon suspension in which aluminum sulfate hydrate, nickel sulfate hydrate, cerous chloride hydrate and the like are suspended to cause a reaction.

The hydrocarbons include aromatic hydrocarbons such as benzene, toluene, xylene, cumene and cymene;
Aliphatic hydrocarbons such as pentane, hexane, heptane, octane, decane, dodecane, hexadecane and octadecane; alicyclic hydrocarbons such as cyclopentane, cyclohexane, cyclooctane and methylcyclopentane; petroleum distillates such as gasoline, kerosene and light oil It is possible to use hydrocarbon solvents such as halogenated aromatic hydrocarbons, aliphatic hydrocarbons and alicyclic hydrocarbons, especially chlorinated compounds and brominated compounds. Further, ethers such as ethyl ether and tetrahydrofuran can also be used. Of these, aromatic hydrocarbons are particularly preferably used.

(2) In a medium such as benzene, toluene, ethyl ether or tetrahydrofuran, water is directly added to an organoaluminum compound such as trialkylaluminum,
A method of applying ice or water vapor.

(3) A method of reacting an organoaluminum compound such as trialkylaluminum with an organotin oxide such as dimethyltin oxide or dibutyltin oxide in a medium such as decane, benzene or toluene.

The aluminoxane may contain a small amount of an organic metal component. Alternatively, the solvent or unreacted organoaluminum compound may be removed from the recovered aluminoxane solution by distillation, and then redissolved in the solvent before use.

Specific examples of the organoaluminum compound used in producing the aluminoxane include those described below as the organoaluminum compound (B-2). Two or more of these may be used in combination. it can. Of these, trialkyl aluminum and tricycloalkyl aluminum are particularly preferred.

The benzene-insoluble organoaluminum oxy compound used in the present invention has an Al component soluble in benzene at 60 ° C. of not more than 10%, preferably not more than 5%, particularly preferably not more than 2% in terms of Al atom. And insoluble or slightly soluble in benzene.

The solubility of such an organoaluminum oxy compound in benzene is determined by comparing the solubility of the organoaluminum oxy compound with 100 milligram atoms of Al to 10 mg.
After suspending in 0 ml of benzene and mixing at 60 ° C. for 6 hours with stirring, the mixture was filtered while hot at 60 ° C. using a G-5 glass filter equipped with a jacket, and the solid part separated on the filter was removed by 60 ° C. After washing four times with 50 ml of benzene at 50 ° C., the amount of Al atoms present in the total filtrate (x
Mmol) (x%).

These organic aluminum oxy compounds (B-1) can be used alone or in combination of two or more. The organoaluminum compound (B-2) used in the present invention is represented by, for example, the following general formula (iii).

R ¹ _n AlX _3-n (iii) (wherein, R ¹ is a hydrocarbon group having 1 to 12 carbon atoms, X is a halogen atom or a hydrogen atom, and n is 1 to 3)
3. In the above general formula (iii), R ¹ has 1 to 1 carbon atoms.
A hydrocarbon group such as an alkyl group, a cycloalkyl group or an aryl group, specifically, a methyl group, an ethyl group, a n-propyl group, an isopropyl group, an isobutyl group, a pentyl group, a hexyl group, Octyl, cyclopentyl, cyclohexyl, phenyl, tolyl and the like.

Such an organoaluminum compound (B-2)
As, specifically, trimethylaluminum, triethylaluminum, triisopropylaluminum,
Trialkylaluminums such as triisobutylaluminum, trioctylaluminum and tri-2-ethylhexylaluminum; alkenylaluminums such as isoprenylaluminum, dimethylaluminumchloride, diethylaluminumchloride, diisopropylaluminumchloride, dialkylaluminums such as diisobutylaluminumchloride and dimethylaluminumbromide Halides; alkyl aluminum sesquihalides such as methyl aluminum sesquichloride, ethyl aluminum sesquichloride, isopropyl aluminum sesquichloride, butyl aluminum sesquichloride, and ethyl aluminum sesquibromide; methyl aluminum dichloride, ethyl aluminum dichloride, isopropyl aluminum Dichloride, alkyl aluminum dihalides such as ethyl aluminum dibromide; diethylaluminum hydride, and alkyl aluminum hydride such as diisobutylaluminum hydride and the like.

As the organoaluminum compound (B-2), a compound represented by the following general formula (iv) can also be used. R ¹ _n AlY _3-n (iv) (R ¹ is the same as above, Y is —OR ² group, —OSiR
³ ₃ group, -OAlR ⁴ ₂ group, -NR ⁵ ₂ group, -SiR ⁶ ₃ group or -N (R ⁷⁾ is AlR ⁸ ₂ group, n is 1-2,
R ² , R ³ , R ⁴ and R ⁸ are a methyl group, an ethyl group, an isopropyl group, an isobutyl group, a cyclohexyl group, a phenyl group and the like, and R ⁵ is a hydrogen atom, a methyl group, an ethyl group,
An isopropyl group, a phenyl group, a trimethylsilyl group and the like, and R ⁶ and R ⁷ are a methyl group and an ethyl group. Specific examples include the following compounds. _{^{(1) R 1 n Al (}} OR 2) a compound represented by the _3-n, e.g., dimethylaluminum methoxide, diethylaluminum ethoxide and diisobutylaluminum _{^{methoxide, (2) R 1 n Al}} (OSiR 3 3) 3- _n , for example, Et ₂ Al (OSiMe ₃ ), (iso-Bu) ₂ Al
(OSiMe _3), such as _{(iso-Bu) 2 Al (} OSiEt 3), (3) R 1 n Al (OAlR 4 2) compounds represented by _{3-n, e.g., Et 2 AlOAlEt 2, (iso} -Bu) ₂ A
lOAl etc. _{(iso-Bu) 2, (} 4) R 1 n Al (NR 5 2)
A compound represented by _3-n , for example, Me ₂ AlNEt ₂ ,
Et ₂ AlNHMe, Me ₂ AlNHEt, Et ₂ AlN
_{(SiMe 3) 2, (iso} -Bu) such as _{2 AlN (SiMe 3) 2,} (5) R 1 n Al (SiR 6 3) a compound represented by _3-n,
For example, (6) R ¹ _n A such as (iso-Bu) ₂ AlSiMe ₃
^{l (N (R 7) AlR} 8 2) a compound represented by the _3-n, for example,
Et ₂ AlN (Me) AlEt ₂ , (iso-Bu) ₂ AlN (E
t) Al (iso-Bu) ₂ etc.

Of these, trialkylaluminum is preferred, and triisobutylaluminum is particularly preferred. These organoaluminum compounds (B-2)
These can be used alone or in combination of two or more.

The compound (B-3) which forms an ion pair by reacting with the metallocene compound (A) used in the present invention is disclosed in JP-A-1-501950 and JP-A-1-50
2036, JP-A-3-179005, JP-A-3-179006, JP-A-3-207703, JP-A-3-207704, USP-532
Examples thereof include Lewis acids, ionic compounds and carborane compounds described in No. 1106 and the like.

As the Lewis acid, triphenylboron,
Tris (4-fluorophenyl) boron, tris (p-tolyl) boron, tris (o-tolyl) boron, tris (3,5-
Dimethylphenyl) boron, tris (pentafluorophenyl) _{boron, MgCl 2, Al 2 O 3} , SiO 2 -Al 2
O _{3 and the} like.

Examples of the ionic compound include triphenylcarbenium tetrakis (pentafluorophenyl) borate, tri-n-butylammonium tetrakis (pentafluorophenyl) borate, N, N-dimethylanilinium tetrakis (pentafluorophenyl) borate, and ferrocarbon. Cenium tetra (pentafluorophenyl) borate and the like can be mentioned.

Examples of the carborane compound include dodecaborane, 1-carboundecaborane, bis-n-butylammonium (1-carbedodeca) borate, tri-n-butylammonium (7,8-dicarboundeca) borate, tri-n-butylammonium (Trideca hydride-7-carboundeca) borate and the like.

These compounds (B-3) can be used alone or in combination of two or more. In the present invention, the components (B-1) and (B-
At least one compound selected from 2) and (B-3) is used, and these can be used in an appropriate combination. Among them, at least (B-
It is preferable to use 1) or (B-3).

The particulate carrier used in the present invention includes:
Granular or fine solid particles having a particle size of 10 to 300 μm, preferably 20 to 200 μm are used. The specific surface area of the particulate carrier is usually 50 to 1000 m ² / g,
The pore volume is desirably from 0.3 to 2.5 cm ³ / g.

As such a particulate carrier, a porous inorganic oxide is preferably used. Specifically, SiO ₂ , A
l ₂ O ₃ , MgO, ZrO ₂ , TiO ₂ , B ₂ O ₃ , CaO,
ZnO, BaO, ThO _2, etc., or a mixture or composite containing them, such as SiO ₂ —MgO, SiO ₂
-Al ₂ O ₃ , SiO ₂ -TiO ₂ , SiO ₂ -V ₂ O ₅ , SiO
_2- Cr ₂ O ₃ , SiO ₂ —TiO ₂ —MgO or the like is used. Among these, SiO ₂ and / or Al ₂ O ₃
The main component is preferably.

A small amount of Na ₂ CO ₃ , K
₂ CO ₃ , CaCO ₃ , MgCO ₃ , Na ₂ SO ₄ , Al ₂ (S
O ₄ ) ₃ , BaSO ₄ , KNO ₃ , Mg (NO ₃ ) ₂ , Al (N
It may contain carbonate, sulfate, nitrate, oxide components such as O ₃ ) ₃ , Na ₂ O, K ₂ O, and Li ₂ O.

An organic compound can also be used as the particulate carrier. For example, an α-olefin having 2 to 14 carbon atoms such as ethylene, propylene, 1-butene and 4-methyl-1-pentene is formed as a main component. (Co) polymer or a polymer or copolymer formed mainly of vinylcyclohexane or styrene can be used.

The prepolymerized catalyst used in the present invention is, for example, a solid catalyst component obtained by contacting the metallocene compound (A) and the component (B) with a particulate carrier in an inert hydrocarbon medium or an olefin medium. Can be prepared by pre-polymerizing a small amount of olefin.

The contact between the particulate support and each of the catalyst components is
It is generally desirable to carry out the reaction at a temperature of -50 to 150C, preferably -20 to 120C for 1 minute to 50 hours, preferably 10 minutes to 25 hours.

Specific examples of the inert hydrocarbon solvent used for preparing the prepolymerized catalyst include aliphatic hydrocarbons such as propane, butane, pentane, hexane, heptane, octane, decane, dodecane and kerosene; cyclopentane, cyclohexane And alicyclic hydrocarbons such as methylcyclopentane; aromatic hydrocarbons such as benzene, toluene and xylene; halogenated hydrocarbons such as ethylene chloride, chlorobenzene and dichloromethane, and mixtures thereof.

The metallocene compound (A) was used as a transition metal atom in an amount of 5 × 10 ⁻⁶ per 1 g of the solid catalyst component.
~ 5 × 10 ^-4 gram atoms, preferably 10 ^-5 to 2 × 10
^In an amount of ^-4 gram atoms, component (B) contains 10 ^{-3 to} 5 as aluminum or boron atoms per gram of particulate support.
× 10 ^-2 gram atoms, preferably 2 × 10 ^-3 to 2 × 10
Desirably, it is carried in an amount of ^-2 gram atoms.

The olefin polymer produced by the prepolymerization is about 0.1 to 500 g, preferably 0.3 to 30 g.
It is desirable that the amount is 0 g, particularly preferably 1 to 100 g.

In the present invention, the prepolymerized catalyst is a transition metal / liter (polymerization volume) in an amount of usually 10 ^-8 to 10 ^-3 gram atom / liter, particularly 10 ^-7 to 10 ^-4 gram atom / liter. Preferably, it is used. When a new prepolymerization catalyst is supplied to the second-stage reactor, the transition metal in the metallocene compound (A) contained in the polymer particles introduced from the first-stage reactor is reacted with the second-stage reaction. The new solid catalyst or the prepolymerized catalyst supplied to the vessel is supplied so that the total amount of the metallocene compound (A) and the transition metal contained in the prepolymerized catalyst falls within the above range.

The use of the prepolymerization catalyst makes it possible to produce a linear low-density polyethylene composition having a small amount of fine powder produced during copolymerization and excellent in particle properties. In the present invention, in addition to the component (B) contained in the prepolymerization catalyst, a component (B) not contained in the prepolymerization catalyst can be used. In this case, the component (B) for the transition metal in the polymerization system may be used. In an atomic ratio of aluminum or boron (Al or B / transition metal) of 5 to 300, preferably 10 to 200, more preferably 15 to 150.

In the present invention, a linear low-density polyethylene composition can be obtained in the form of granular particles by the above-described gas phase polymerization. The average particle size of the particles is 250 to 30.
It is desirably about 00 μm, preferably about 400 to 1500 μm.

[0091]

According to the present invention, LLDPE having a narrow composition distribution can be obtained with high polymerization activity without generating a polymer lump or a sheet-like material in a fluidized bed.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a gas phase polymerization method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 ... First fluidized bed reactor 12 ... Supply line 13 ... Blower 14 ... Heat exchanger 15 ... Supply line 16 ... Circulation line 17 ... Dispersion plate 18 ... Fluidized bed 19 ... Deceleration area 21 ... Second fluidized bed reactor 22 ... supply line 23 ... blower 24 ... heat exchanger 25 ... transport line 26 ... circulation line 27 ... dispersion plate 28 ... fluidized bed 29 ... deceleration region 30 ... extraction line 31 ... solid-gas separation container 32 ... solid-gas separation container 33 ... Valve 34 ... Valve 35 ... Rotary valve 41 ... Centrifugal blower

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Satoru Oya 3 Chigusa Coast, Ichihara-shi, Chiba Mitsui Chemicals Co., Ltd. (72) Inventor Shotaro Matsuda 1-2-1, Waki, Waki-cho, Kuga-gun Yamaguchi Prefecture No. Mitsui Chemicals Co., Ltd. F-term (reference) 4J002 BB04W BB04X BB05X BB15W 4J011 AA05 DA06 DB13 DB15 MA01 MA02 MA04 MA05 MA11 MA14 MA19 MB01 4J100 AA02P AA03Q AA04Q AA07Q AA16Q AA17Q AA21 DA43A

Claims (2)

[Claims] 1. A catalyst comprising two gas-phase fluidized-bed reactors connected in series in the presence of a metallocene-supported catalyst in which an olefin has been pre-polymerized, and a gas flow of a fluidizing gas flowing through the fluidized bed. When producing a linear low-density polyethylene composition by copolymerizing ethylene and an α-olefin having 3 to 10 carbon atoms in a fluidized bed in which solid particles containing A mixture containing a saturated aliphatic hydrocarbon having 2 to 10 atoms is introduced into the fluidized bed as a two-phase mixture of gas and liquid, and the first-stage polymerization temperature is set to T ₁ (° C.).
When the polymerization temperature of the second stage is T ₂ (° C.), T ₁ and T ₂ satisfy the relationship represented by T ₁ ≦ T ₂ <T ₁ +30, and When the ethylene partial pressure is P ₁ (MPa) and the ethylene partial pressure in the second stage reactor is P ₂ (MPa), P ₁ and P ₂ are P ₁ ≦ P ₂ <P ₁ +1.
0, and the content of saturated aliphatic hydrocarbons in the fluidized gas of the first-stage reactor is 1.0 to 20 mol%, and the content of saturated aliphatic hydrocarbons in the fluidized gas of the second-stage reactor is Under the condition that the content of the aliphatic hydrocarbon is 1.0 to 20 mol%, the flow index is 0.01 to 5 in the first stage reactor.
0 g / 10 min and a density of 0.860-0.9
A high molecular weight polyethylene in the range of 40 g / cm ³ was produced, and the melt index was 5 to 5 in the second stage reactor.
It is within the range of 3000 g / 10 minutes and the density is 0.900 to
Producing a low molecular weight polyethylene having a weight ratio of high molecular weight polyethylene to low molecular weight polyethylene in the range of 30:70 to 80:20 in the range of 0.975 g / cm ^3. For producing a linear low-density polyethylene composition. 2. The melt index is 0.02 to 3.5.
g / 10 minutes, and the melt flow ratio is 30 to 150.
And the density is 0.910 to 0.960 g / cm
^3. The method for producing a linear low-density polyethylene composition according to claim 1, wherein the composition falls within the range of ³ .