JP3315746B2 - Olefin polymerization method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for polymerizing olefins, and more particularly, to an olefin capable of producing olefin polymers having excellent particle properties stably and continuously over a long period of time by a gas phase polymerization method. A polymerization method.

[0002]

BACKGROUND OF THE INVENTION Olefin polymers typified by polyethylene or linear low-density polyethylene (LLDPE), which is a copolymer of ethylene and an α-olefin, are widely used as materials for film formation. ing.

Conventionally, such olefin polymers have been prepared by co-polymerization of olefins by a solution polymerization method or a suspension polymerization method in the presence of a titanium-based solid catalyst component containing magnesium, titanium and halogen as essential components. ) It is produced by polymerizing.

By the way, when the above polymerization is carried out by a gas phase polymerization method, a polymer can be obtained in the form of particles, and a particle precipitation step or a particle separation step after the polymerization becomes unnecessary.
Therefore, it is known that the manufacturing process can be simplified and the manufacturing cost can be reduced.

However, conventionally, in the gas phase polymerization method, particularly in the gas phase polymerization of a copolymer such as LLDPE, the produced polymer locally aggregates into a polymer mass, In some cases, they adhered and aggregated on the wall of the container to form a sheet-like mass. When such a sheet-like polymer mass is formed, it accumulates on the gas dispersion plate below the fluidized bed, disturbing the normal flow or clogging the hole of the gas dispersion plate, causing a reaction. The normal operation of the system was significantly impaired, and eventually the polymerization operation was stopped.

[0006] In the conventional gas phase polymerization method, there is also a problem with fine powdery polymer particles. In other words, when polymer particles are grown with a solid catalyst as a nucleus in the reaction system, in industrial continuous polymerization, the residence time of the particles has a distribution, so that the polymerization operation always includes insufficiently grown fine powder particles. In particular, in the case of gas phase polymerization using a highly active catalyst exhibiting a high polymerization activity, fine powder particles were easily generated due to the collapse of the solid catalyst component during the polymerization. These fine powder particles are easily scattered out of the fluidized bed, which is the reaction system, and accompany the fluidizing gas circulation line, clogging the cooling heat exchanger, or malfunctioning of the circulating gas blower or gas in the lower part of the fluidized bed. This causes clogging of the dispersion plate. Therefore, a deceleration zone for fluidizing gas is provided at the top of the polymerization vessel to prevent it from jumping out of the polymerization vessel, or a device such as a cyclone is installed at the circulating gas outlet from the polymerization vessel to collect fine powder particles. And then returned to the polymerization reactor again.

However, industrially, providing a large deceleration region above the polymerization vessel, which is a large-capacity pressure vessel, causes an increase in the size of the polymerization vessel (that is, a decrease in productivity), an increase in equipment costs, and an increase in cyclone and the like. However, these measures have not been able to provide reasonable countermeasures due to new problems such as the blockage of the fine powder particle recycling line from the lower part of the cyclone.

In view of the above prior art, the present inventor has conducted intensive studies on a gas phase polymerization method for olefins. As a result, in the presence of a low boiling point solvent, group IVB of the periodic table having a cyclopentadienyl skeleton. To obtain a prepolymerized catalyst obtained by prepolymerizing a large amount and continuously of one or two or more olefins selected from olefins having 2 to 18 carbon atoms on a solid catalyst containing a transition metal compound of By feeding the olefin in the gas phase together with a low boiling point solvent to the olefin polymer in the gas phase, it is possible to prevent the formation of a sheet-like polymer, and to stably produce an olefin polymer with excellent particle properties over a long period of time. The present invention was found to be able to be produced in a compact manner and the size of the gas phase polymerization vessel could be reduced, and the present invention was completed.

[0009]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned prior art, and is intended to stably produce an olefin polymer having excellent particle properties by a gas phase polymerization method over a long period of time. It is an object of the present invention to provide a method for polymerizing an olefin that can be produced in a specific manner.

[0010]

SUMMARY OF THE INVENTION An olefin polymerization method according to the present invention comprises:
[I] Periodic Table IV having a cyclopentadienyl skeleton
An olefin is prepolymerized on a solid catalyst (i) containing a Group B transition metal compound to prepare a prepolymerization catalyst (ii), and the obtained prepolymerization catalyst (ii) is supplied into a gas phase polymerization reactor. In the prepolymerization step, [II] a gas phase polymerization or copolymerization of an olefin with the prepolymerization catalyst (ii) in the presence of a low-boiling non-polymerizable hydrocarbon in a fluidized bed that is a reaction system maintained in a fluidized state. [III] a first circulation step of circulating a portion of the low-boiling non-polymerizable hydrocarbon discharged from the upper part of the gas phase polymerization vessel from below the gas phase polymerization vessel, and [IV] a gas phase polymerization A second circulating step of liquefying a part of the low-boiling non-polymerizable hydrocarbon discharged from the upper part of the reactor and circulating the liquefied hydrocarbon in the gas-phase polymerization reactor, wherein the [III] and / or [IV] circulating In the gas phase polymerization of the olefin supplied to the step, in the above [I] preliminary polymerization step, In the presence of a liquid low-boiling non-polymerizable hydrocarbon, 50 to 12 per gram of the solid catalyst (i)
The olefin is continuously prepolymerized or copolymerized in an amount of 00 g to prepare a prepolymerized catalyst (ii), and the prepolymerized catalyst (ii) is continuously vaporized together with a liquid low-boiling non-polymerizable hydrocarbon. It is characterized in that it is supplied into a phase polymerization vessel.

In the prepolymerization step (I), two or more olefins selected from olefins having 2 to 18 carbon atoms are continuously prepolymerized in the presence of a liquid low-boiling non-polymerizable hydrocarbon to obtain the following conditions: Prepolymerization catalyst (i
i) is prepared, and the prepolymerization catalyst (ii) is continuously supplied together with a liquid hydrocarbon into a gas-phase polymerization reactor.

Olefin polymerization amount; 1 g of solid catalyst (i)
The density is 0.880 to 0.970 g / cm ³ , and the intrinsic viscosity [η] is 0.5 to 8 dl / g.

According to the olefin polymerization method of the present invention, an olefin polymer having excellent particle properties can be stably and continuously produced over a long period of time by a gas phase polymerization method.

[0014]

DETAILED DESCRIPTION OF THE INVENTION Hereinafter, the olefin polymerization method according to the present invention will be specifically described. In the present invention, the term "polymerization" may be used to mean not only homopolymerization but also copolymerization, and the term "polymer" refers to not only homopolymers but also copolymers. Is sometimes used with the meaning including.

In the olefin polymerization method according to the present invention,
As the catalyst, a prepolymerized catalyst (ii) prepared in the following [I] prepolymerization step is used. First, the solid catalyst (i) used for preparing the prepolymerized catalyst (ii) will be described.

The solid catalyst (i) used in the present invention comprises:
It is obtained by contacting (a) a transition metal compound, (b) aluminoxane, and (c) a carrier compound. like this
(a) Examples of the transition metal compound include transition metal compounds of Group IVB of the periodic table having a cyclopentadienyl skeleton represented by the following formula.

ML _{x wherein} M is a transition metal selected from the group consisting of Zr, Ti, Hf, V, Nb, Ta and Cr, L is a ligand coordinated to the transition metal, and at least One L is a ligand having a cyclopentadienyl skeleton, and L other than the ligand having a cyclopentadienyl skeleton has 1 to 1 carbon atoms.
2, a hydrocarbon group, an alkoxy group, an aryloxy group, a trialkylsilyl group, an SO ₃ R group (where R is a hydrocarbon group having 1 to 8 carbon atoms which may have a substituent such as halogen), a halogen atom Or a hydrogen atom, and x is the valence of the transition metal. Examples of the ligand having a cyclopentadienyl skeleton include a cyclopentadienyl group, a methylcyclopentadienyl group, a dimethylcyclopentadienyl group, a trimethylcyclopentadienyl group,
Tetramethylcyclopentadienyl group, pentamethylcyclopentadienyl group, ethylcyclopentadienyl group, methylethylcyclopentadienyl group, propylcyclopentadienyl group, methylpropylcyclopentadienyl group, butylcyclopentadiene Examples include alkyl-substituted cyclopentadienyl groups such as enyl group, methylbutylcyclopentadienyl group and hexylcyclopentadienyl group, or indenyl group, 4,5,6,7-tetrahydroindenyl group and fluorenyl group. Can be. These groups may be substituted with a halogen atom, a trialkylsilyl group or the like.

Among the ligands that coordinate to these transition metals, an alkyl-substituted cyclopentadienyl group is particularly preferred. When the compound represented by the above general formula contains two or more groups having a cyclopentadienyl skeleton,
Groups having a cyclopentadienyl skeleton are substituted with an alkylene group such as ethylene and propylene, a substituted alkylene group such as isopropylidene and diphenylmethylene, a silylene group or a dimethylsilylene group, a diphenylsilylene group, and a methylphenylsilylene group. They may be bonded via a silylene group or the like.

Specific examples of the ligand L other than the ligand having a cyclopentadienyl skeleton include the following. Examples of the hydrocarbon group having 1 to 12 carbon atoms include an alkyl group, a cycloalkyl group, an aryl group, and an aralkyl group. More specifically, examples of the alkyl group include a methyl group, an ethyl group, a propyl group, and an isopropyl group. Group, butyl group, etc., cycloalkyl group, cyclopentyl group, cyclohexyl group, etc., aryl group, phenyl group, tolyl group, etc., and aralkyl group, benzyl group, neophyl group, etc. And the like.

As the alkoxy group, a methoxy group,
An ethoxy group, a butoxy group and the like are exemplified. As the aryloxy group, a phenoxy group and the like are exemplified. As the halogen, fluorine, chlorine, bromine, iodine and the like are exemplified.

Examples of the ligand represented by SO ₃ R include a p-toluenesulfonato group, a methanesulfonato group, and a trifluoromethanesulfonato group. When the valence of the transition metal is 4, for example, such a transition metal compound is more specifically represented by the following formula.

R ² _k R ³ _l R ⁴ _m R ⁵ _n M ( _where M is the above-mentioned transition metal, R ² is a group having a cyclopentadienyl skeleton (ligand), and R ³ , R ⁴ and R ⁵ are a group having a cyclopentadienyl skeleton, an alkyl group, a cycloalkyl group, an aryl group, an aralkyl group, an alkoxy group, an aryloxy group, a trialkylsilyl group, an SO ₃ R group, a halogen atom or a hydrogen atom. And k is an integer of 1 or more, and k + 1 + m + n = 4.) In the present invention, in the above formula R ² _k R ³ _l R ⁴ _m R ⁵ _n M,
A metallocene compound in which at least two of R ² , R ³ , R ⁴ and R ⁵ , that is, R ² and R ³ are groups (ligands) having a cyclopentadienyl skeleton is preferably used. These groups having a cyclopentadienyl skeleton include alkylene groups such as ethylene and propylene, substituted alkylene groups such as isopropylidene and diphenylmethylene, and silylene groups or substituted silylene groups such as dimethylsilylene, diphenylsilylene and methylphenylsilylene groups. May be connected via R ⁴ and R ⁵ are a group having a cyclopentadienyl skeleton, an alkyl group, a cycloalkyl group, an aryl group, an aralkyl group, an alkoxy group, an aryloxy group, a trialkylsilyl group, SO ₃
R, a halogen atom or a hydrogen atom.

Specific examples of the transition metal compound in which M is zirconium are shown below. Bis (indenyl) zirconium dichloride, bis (indenyl)
Zirconium dibromide, bis (indenyl) zirconium bis (p-toluenesulfonato) bis (4,5,6,7-tetrahydroindenyl) zirconium dichloride, bis (fluorenyl) zirconium dichloride, ethylenebis (indenyl) zirconium dichloride, ethylene Bis (indenyl) zirconium dibromide, ethylenebis (indenyl) dimethylzirconium, ethylenebis (indenyl) diphenylzirconium, ethylenebis (indenyl) methylzirconium monochloride, ethylenebis (indenyl) zirconiumbis (methanesulfonato), ethylenebis ( Indenyl) zirconium bis (p-toluenesulfonate), ethylenebis (indenyl) zirconiumbis (trifluoromethanesulfonate), ethylenebis (4,5,6,7 -Tetrahydroindenyl) zirconium dichloride, isopropylidene (cyclopentadienyl-fluorenyl) zirconium dichloride, isopropylidene (cyclopentadienyl-methylcyclopentadienyl) zirconium dichloride, dimethylsilylene bis (cyclopentadienyl) zirconium dichloride, Dimethylsilylenebis (methylcyclopentadienyl) zirconium dichloride, dimethylsilylenebis (dimethylcyclopentadienyl) zirconium dichloride, dimethylsilylenebis (trimethylcyclopentadienyl) zirconium dichloride, dimethylsilylenebis (indenyl) zirconium dichloride, dimethylsilylene Bis (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, diphenyl Silylene bis (2,4,7-trimethylindenyl) zirconium dichloride, methylphenylsilylene bis (indenyl) zirconium dichloride, bis (cyclopentadienyl) Ruconium dichloride, bis (cyclopentadienyl) zirconium dibromide, bis (cyclopentadienyl) methylzirconium monochloride, bis (cyclopentadienyl) ethylzirconium monochloride, bis (cyclopentadienyl) cyclohexylzirconium 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) dibenzylzil , Bis (cyclopentadienyl) zirconium methoxychloride, bis (cyclopentadienyl) zirconium ethoxychloride, bis (cyclopentadienyl) zirconium bis (methanesulfonato), bis (cyclopentadienyl) zirconium bis (p -Toluenesulfonato), bis (cyclopentadienyl) zirconium bis (trifluoromethanesulfonato), bis (methylcyclopentadienyl) zirconium dichloride, bis (dimethylcyclopentadienyl) zirconium dichloride, bis (dimethylcyclopentadiene) Enyl) zirconium ethoxycyclolide, bis (dimethylcyclopentadienyl) zirconium bis (trifluoromethanesulfonato), bis (ethylcyclopentadienyl) zirconium dichloride, Bis (methylethylcyclopentadienyl) zirconium dichloride, bis (propylcyclopentadienyl) zirconium dichloride, bis (methylpropylcyclopentadienyl) zirconium dichloride, bis (butylcyclopentadienyl) zirconium dichloride, bis (methylbutyl Cyclopentadienyl) zirconium dichloride, bis (methylbutylcyclopentadienyl) zirconium bis (methanesulfonato), bis (trimethylcyclopentadienyl) zirconium dichloride, bis (tetramethylcyclopentadienyl) zirconium dichloride, bis ( Pentamethylcyclopentadienyl) zirconium dichloride, bis (hexylcyclopentadienyl) zirconium dichloride, bis (trimethylsilylcyclyl) Pentadienyl) zirconium dichloride.

In the above examples, disubstituted cyclopentadienyl ring includes 1,2- and 1,3-substituted, and tri-substituted 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.

In the above zirconium compound, a compound in which zirconium is replaced with titanium, hafnium, vanadium, niobium, tantalum or chromium can also be used.

In the present invention, as the transition metal compound (a),
A zirconocene compound in which the central metal atom is zirconium and has a ligand having at least two cyclopentadienyl skeletons is preferably used.

The aluminoxane (b) used for the preparation of the solid catalyst (i) is specifically represented by the following general formula <1.
> And the compound represented by the general formula <2>.

[0028]

Embedded image

In the general formulas <1> and <2>, R is a hydrocarbon group such as a methyl group, an ethyl group, a propyl group and a butyl group, preferably a methyl group, an ethyl group, particularly preferably a methyl group. , M is 2 or more, preferably 5
It is an integer of ４０40.

Here, this aluminoxane has the formula (OA)
l (R ¹ )) and an alkyloxyaluminum unit of the formula (OAl (R ² )) wherein R ¹ and R ² are
And R ¹ and R ² each represent a different group.]. In that case, the methyloxyaluminum unit (OAl (CH
₃ )) is at least 30 mol%, preferably at least 50 mol%,
Particularly preferred is an aluminoxane formed from a mixed alkyloxyaluminum unit containing at least 70 mol%.

As a method for producing such an aluminoxane, for example, the following method can be exemplified. (1) Compounds containing water of adsorption or salts containing water of crystallization, such as hydrated magnesium chloride, hydrated copper sulfate, hydrated aluminum sulfate, hydrated nickel sulfate, hydrated cerous chloride A method of adding a trialkylaluminum to a hydrocarbon medium suspension of (1) to cause a reaction. (2) A method in which water is allowed to directly act on trialkylaluminum in a medium such as benzene, toluene, ethyl ether, and tetrahydrofuran.

Among these methods, it is preferable to adopt the method (1). The aluminoxane may contain a small amount of an organic metal component other than aluminum.

In the present invention, as the aluminoxane (b), a benzene-insoluble aluminum oxy compound as disclosed in JP-A-2-276807 can be used.

Specific examples of the carrier compound (c) used for preparing the solid catalyst (i) include Al ₂ O ₃ , SiO ₂ and B ₂
O ₃ , MgO, CaO, TiO ₂ , ZnO, ZnO ₂ , SnO
₂ , BaO, ThO, styrene-divinylbenzene copolymer and the like are used.

Of these carrier compounds, Al ₂ O ₃ , S
iO ₂ and styrene - divinylbenzene copolymer are preferably used. The solid catalyst (i) used in the present invention comprises the catalyst components (a), (b) and (c) as described above.
And, if necessary, an electron donor, a reaction aid,
It may contain a magnesium compound.

Examples of such electron donors include alcohols, phenols, ketones, aldehydes, carboxylic acids, organic acid halides, esters of organic or inorganic acids, ethers, acid amides, acid anhydrides, Examples include oxygen-containing electron donors such as alkoxysilanes, nitrogen-containing electron donors such as ammonia, amines, nitriles, and isocyanates, and organic silicon compounds represented by the following general formula.

R _n Si (OR ′) _4-n (wherein R and R ′ are hydrocarbon groups, and 0 <n <4
It is. Also, examples of the electron donor include other nitrogen-containing compounds, other oxygen-containing compounds, and phosphorus-containing compounds.

As such a nitrogen-containing compound, 2,6-
Examples include substituted piperidines, 2,5-substituted piperidines, substituted methylene diamines, substituted methylene diamines, and the like.

As the oxygen-containing compound, 2,6-substituted tetrahydropyrans, 2,5-substituted tetrahydropyrans and the like can be used. Phosphorous esters can be used as the phosphorus-containing compound.

These electron donors (b) may be used as a mixture of two or more. Organic and inorganic substances containing silicon, phosphorus, aluminum and the like can be used as the reaction assistant.

The solid catalyst (i) used in the present invention
May contain, if necessary, the following organometallic compounds together with the above-mentioned catalyst components (a), (b) and (c).

[0042] In R ^a _n AlX _3-n type, R ^a is a hydrocarbon group having 1 to 12 carbon atoms, X is halogen or hydrogen, n represents 1 to 3.

In the above formula, ^Ra is a hydrocarbon group having 1 to 12 carbon atoms, for example, an alkyl group, a cycloalkyl group or an aryl group, and specifically, methyl, ethyl, n-propyl, isopropyl Group, isobutyl group, pentyl group, hexyl group, octyl group, cyclopentyl group, cyclohexyl group, phenyl group, tolyl group and the like.

Examples of such organometallic compounds include trialkylaluminum, alkenylaluminum, dialkylaluminum halide, alkylaluminum sesquihalide, alkylaluminum dihalide, and alkylaluminum hydride.

Further, use of a compound represented by the following formula:
Can also. R^a _nAlY_3-n Where R^aIs the same as above, and Y is -OR^bGroup, -OS
i R^c _Three Group, -OAlR ^d _TwoGroup, -NR^e _Two Group, -SiR^f _Three 
Group or -N (R^g) AlR^h _Two And n is 1 to 2
And R^b, R^c, R^dAnd R^hIs a methyl group, ethyl
Group, isopropyl group, isobutyl group, cyclohexyl
Group, phenyl group, etc.^eIs hydrogen, methyl, d
Butyl, isopropyl, phenyl, trimethylsilyl
And R^fAnd R^gIs a methyl group or an ethyl group
What is it?

Specific examples of such an organometallic compound include dimethylaluminum methoxide, diethylaluminum ethoxide, diisobutylaluminum methoxide, etc., Et ₂ Al (OSiMe ₃ ), (iso-Bu) ₂ Al (O ₂
Et ₂ Al such as (SiMe ₃ ) and (iso-Bu) ₂ Al (OSiEt ₃ )
OAlEt ₂ , (iso-Bu) ₂ AlOAl (iso-Bu) ₂ , Me ₂
AlNEt ₂ , Et ₂ AlNHMe, Me ₂ AlNHEt, Et ₂
AlN (Me ₃ Si) ₂ , (iso-Bu) ₂ AlN (Me ₃ Si) _2, etc.
Et ₂ AlN (Me) AlEt, such as (iso-Bu) ₂ AlSiMe _3
2 , (iso-Bu) ₂ AlN (Et) Al (iso-Bu) _{2 and the} like.

As a complex alkylated product of a Group I metal and aluminum, a compound represented by the general formula M ¹ AlR ^j ₄ (where M ¹ is Li, Na, K, and R ^j has 1 to 1 carbon atoms)
5 hydrocarbon groups. ) Can be exemplified, and specifically, LiAl (C ₂ H ₅ ) ₄ and LiAl (C ₇ H ₁₅ ) ₄
And the like.

Of these, alkyl aluminum compounds and trialkyl aluminum compounds to which two or more aluminum compounds are bonded as described above are preferred. These can be used alone or in combination of two or more.

In the present invention, the above-mentioned transition metal compound
When the solid catalyst (i) is formed from (a), aluminoxane (b) and the carrier compound (c), the contact condition and the contact sequence vary depending on the contact conditions, but the transition is relative to 1 mol of the carrier compound (c). The metal compound (a) is used in an amount of 0.1 to 0.001, preferably 0.05 to 0.002 mol, and the aluminoxane (c) is used in an amount of 0.1 to 10, preferably 0.2 to 5 mol. It is used in molar amounts.

The temperature at which these compounds are brought into contact is
It is usually -20 to 80C, preferably 0 to 50C. The prepolymerized catalyst (ii) used in the present invention is prepared in the [I] prepolymerization step using the solid catalyst (i) as described above.

Here, the olefin polymerization method according to the present invention will be described in detail with reference to FIG. [I] In the prepolymerization step, first, the olefin, the solid catalyst (i), the organometallic compound, and the liquid low-boiling non-polymerizable hydrocarbon are continuously supplied to the prepolymerizer 1 to solidify the solid. The olefin is prepolymerized on the solid catalyst (i).

The low-boiling non-polymerizable hydrocarbon used in the present invention is in a liquid state in the [I] prepolymerization step and is easily volatile in the [II] main polymerization (gas phase polymerization) step described later. And [I] a hydrocarbon that does not polymerize under olefin polymerization conditions including the prepolymerization step. It is preferable that the low-boiling non-polymerizable hydrocarbon is easily condensed at a low temperature and can be easily liquefied by a refrigerant such as water in a condenser 10 described later, for example.
Specific examples of such a low-boiling non-polymerizable hydrocarbon include a saturated hydrocarbon, and more specifically, for example, propane, n-butane, i-butane, n-pentane, i- Pentane and micropentane can be mentioned.

These can be used alone or in combination. The olefin used in the present invention is preferably an α-olefin having 2 to 18 carbon atoms, for example, ethylene, propylene, 2-methylpropylene, 1-
Butene, 1-hexene, 1-pentene, 4-methyl-1-pentene, 3-methyl-1-pentene, 1-heptene, 1-octene, 1
-Nonene, 1-decene, 1-undecene, 1-dodecene and the like.

Further, a polyene, for example, can be copolymerized with the olefin. Examples of such a polyene include butadiene, isoprene, 1,4-hexadiene, dicyclopentadiene, 5-ethylidene-2-norbornene, and the like.

Such an olefin may be the same as or different from the olefin used in the main polymerization described later. In the prepolymerization, the above-mentioned olefin is polymerized or copolymerized.

In the present invention, during the prepolymerization, it is preferable to prepolymerize ethylene and α-olefin among the above-mentioned olefins. In the main polymerization step described below, in the presence of a prepolymerized catalyst (ii) obtained by precopolymerizing such ethylene and α-olefin,
When ethylene and an α-olefin are copolymerized, linear low-density polyethylene (L
LDPE) can be produced, and the main polymerization can be continuously performed stably for a long period of time, which is preferable.

The pre-polymerization is carried out continuously, specifically, as follows. The type of the prepolymerizer 1 is not to be specified, and a general tank type or loop type is used. The prepolymerizer 1 is maintained under stirring conditions such that the solid catalyst (i) is well suspended in the liquid low-boiling non-polymerizable hydrocarbon, and the olefin is preferably subjected to so-called slurry polymerization.

[I] In the prepolymerization step, the solid catalyst (i)
Varies depending on the type of the catalyst component used, the preparation conditions, and the like, but is usually used in an amount as exemplified below.

For the solid catalyst (i), the transition metal compound (a) is usually about 0.0001 to 20 mmol, preferably about 0.1 to 1 mmol per 1 kg of the low-boiling non-polymerizable hydrocarbon. 0005 to 10 mmol, particularly preferably 0.0
Desirably, it is used in an amount of from 1 to 2 mmol. Alumoxane (b) or an organometallic compound as described above may be used together with the solid catalyst (i), and these are usually used in an amount of about 0 to 300 per mole of the transition metal atom in the transition metal compound (a). Desirably, it is used in an amount of about 1 mol, preferably about 1 to 100 mol, particularly preferably 2 to 50 mol.

[I] The polymerization temperature in the preliminary polymerization step is as follows:
Although it depends on the type of olefin to be polymerized, it is usually about -30 to + 90C, preferably about 0 to 70C. In the [I] prepolymerization step, a molecular weight regulator such as hydrogen can be used.

[I] In the prepolymerization step, the olefin is prepolymerized in an amount of 50 to 1200 g, preferably 100 to 1000 g per 1 g of the solid catalyst (i) as described above to prepare the prepolymerized catalyst (ii). Prepare. The polymerization ratio of this preliminary polymerization amount to the total polymerization amount including the main polymerization is 0.1 to 20.
%, Preferably 0.5 to 20% by weight, particularly preferably 1 to 10% by weight.

The prepolymerized catalyst (ii) thus obtained
Usually has a density of 0.880 to 0.970 g / cm ³ ,
Preferably it is 0.900 to 0.950 g / cm ³ . The intrinsic viscosity [η] is usually 0.5 to 8 dl / g, preferably 1 to 5 dl / g.

In the present invention, in the prepolymerization catalyst (ii) obtained in the [I] prepolymerization step, the olefin is prepolymerized in a larger amount than the conventional general prepolymerization catalyst.
Such a large amount of olefin, and the prepolymerized catalyst (ii), which has been prepolymerized continuously, has little variation in the amount of prepolymerization, is less likely to aggregate with each other, and is performed in the gas phase of the next step In the main polymerization, an olefin polymer having excellent particle properties can be produced. Further, in such a prepolymerized catalyst (ii), the content of fine powder particles is small. Therefore, in the gas phase polymerization performed in the presence of such a pre-polymerization catalyst (ii), powdery particles scattered outside the reaction system (fluidized bed) are reduced, and the fluidized gas deceleration region ( Hereinafter, the diameter of the deceleration region 3a can be reduced. Depending on the conditions, it is possible to eliminate the deceleration range 3a,
In this case, the polymerization can be performed even in a cylindrical reactor. In addition, a cyclone or the like for collecting fine powder particles can be eliminated.

In the olefin polymerization method according to the present invention,
The pre-polymerization catalyst (ii) continuously prepared in the above [I] pre-polymerization step is continuously vaporized through the line 2 while being suspended in a liquid low-boiling non-polymerizable hydrocarbon. Phase polymerization vessel
3 to perform main polymerization. At this time, it may be supplied directly into the reaction system (fluidized bed) 5 maintained in a fluidized state, or may be supplied to the vicinity 5a of the fluidized bed powder surface.

As described above, when the prepolymerized catalyst (ii) suspended in the liquid low-boiling non-polymerizable hydrocarbon is supplied to the gas-phase polymerization reactor 3 , the liquid low-boiling non-polymerizable hydrocarbon is easily vaporized,
The rapid polymerization causes the prepolymerization catalyst (ii) to be uniformly dispersed in the reaction system 5 .

[II] In the main polymerization step, an olefin and a low-boiling non-polymerizable hydrocarbon are supplied from below the gas phase polymerization reactor 3 through a line 8 to bring the reaction system 5 into a fluidized state (fluidized bed).
The olefin is gas-phase polymerized on the pre-polymerization catalyst (ii) while maintaining the temperature.

At this time, in addition to the pre-polymerization catalyst (ii), if necessary, the above-mentioned organometallic compound, a co-catalyst such as aluminoxane (b) or each compound such as an electron donor may be added to the line 15 for example. Can be supplied to the gas-phase polymerization reactor 3 via

As the olefin to be polymerized, monomers similar to the olefin used in the above-mentioned prepolymerization or the polyene used as necessary can be used. These may be the same as or different from the monomers used in the prepolymerization.

In the main polymerization, these monomers are polymerized or copolymerized. Representative examples of the present invention include, among these, copolymerization of ethylene and an α-olefin.

[II] In the main polymerization step, the polymerization conditions vary depending on the olefin to be polymerized and the fluidized state of the reaction system (fluidized bed) 5.
0 ° C, preferably 50-120 ° C, more preferably 70 ° C.
At 〜110 ° C., the polymerization pressure is from 1 to 100 kg / cm ² , preferably from ² to 40 kg / cm ² .

[II] In the main polymerization step, the olefin and the low-boiling non-polymerizable hydrocarbon are usually
It is supplied by blowing into a reaction system (fluidized bed) 5 from a dispersion plate 4 such as a perforated plate provided below in the inside 3 . At this time, the olefin and the low-boiling non-polymerizable hydrocarbon are usually supplied in a gaseous state at a flow rate capable of maintaining the reaction system 5 in a fluid state. Specifically, usually, when the minimum fluidization velocity and U _mf, about 3U _mf ~50U _mf, is preferably supplied at a flow rate of about 5U _mf ~30U _mf.

In the present invention, the reaction system (fluidized bed) 5 can be mechanically stirred. The stirring can be performed using various types of stirrers such as an squid-type stirrer, a screw-type stirrer, and a ribbon-type stirrer.

In the main polymerization, a molecular weight regulator such as hydrogen can be used if necessary, and can be supplied from an arbitrary place in the gas phase polymerization vessel 3, for example, from the line 15. The polymer produced is passed through a line 14 to a gas phase polymerization reactor.
Extract continuously from 3 .

The main polymerization can be carried out in two or more stages. In the present invention, the low-boiling non-polymerizable hydrocarbon discharged from above the gas phase polymerization vessel 3 is circulated to the reaction system 5 as described below. The low-boiling non-polymerizable hydrocarbon discharged from above the gas phase polymerization vessel 3 usually contains unreacted olefin.

[III] In the first circulation step, a part of the non-polymerizable hydrocarbon having a low boiling point discharged from above the gas phase polymerization vessel 3 is passed through the line 6 and the line 8 below the gas phase polymerization vessel 3 . And fed to the above [II] main polymerization step.

At this time, the low-boiling non-polymerizable hydrocarbon circulated is cooled by the heat exchanger 7 to remove heat of polymerization. The low-boiling non-polymerizable hydrocarbon circulated below the gas-phase polymerization vessel 3 is usually in a gaseous state, so that the reaction system 5 can be maintained in a fluid state as described above.

Further, in the [IV] second circulation step, a part of the low-boiling non-polymerizable hydrocarbon discharged from above the gas-phase polymerization reactor 3 is transferred to the condenser 10 via the lines 6 and 9.
Where the condensate drum 11 and the condensate circulation pump 1
6, circulate through the line 13 to the reaction system 5 in the gas phase polymerization reactor 3 .

In the condenser 10, it is preferable that the low-boiling non-polymerizable hydrocarbon is usually cooled by a general refrigerant such as water to be in a liquid state. The low-boiling non-polymerizable hydrocarbon containing unreacted olefin that is not liquefied in the condenser 10 can be circulated from the line 8 to the [III] first circulation step via the line 12.

A part of the low-boiling non-polymerizable hydrocarbon liquefied in the condenser 10 may be circulated to the prepolymerizer 1. In such a circulation system, usually, unreacted monomers are introduced into the condenser 10 via the lines 6 and 9 together with the low-boiling non-polymerizable hydrocarbon as described above.

Therefore, when ethylene and α-olefin are copolymerized in the main polymerization step, unreacted olefins other than ethylene, that is, α-olefins, are condensed in the condenser 10 together with the low boiling non-polymerizable hydrocarbon. The α-olefin that is easily liquefied and liquefied can be easily circulated to the prepolymerizer 1 through the above-mentioned line together with the low-boiling non-polymerizable hydrocarbon.

The above [III] first and / or [I
V] In the second circulation step, the supply of the olefin can be carried out from any place, for example, via the line 15.
Further, if necessary, a low-boiling non-polymerizable hydrocarbon may be newly supplied from any place.

In the present invention, in the [IV] second circulation step, the liquefied low-boiling non-polymerizable hydrocarbon is added to the gas-phase polymerization reactor 3
In circulating the reaction system 5 of the inner, the reaction system can be recycled to any position of the reaction system in a fluidized state in inter alia fluidized state (fluidized layer) 5 powder near the surface 5a, i.e. fluidized powder It is preferable to circulate the powder particles at a position where they can come in contact with the powdery particles scattered upward from the surface in a liquid state. That is, the powdery particles to be scattered reaction system (fluidized layer) to 5 outside in contact with the low-boiling non-polymerizable carbon hydrocarbon liquid, powder particles are prevented from scattering to the reaction system 5 outside It is preferable to circulate the low-boiling non-polymerizable hydrocarbon from the position where it can be obtained. Specifically, when the fluidized bed powder surface height is H, the liquid low-boiling non-polymerizable hydrocarbon is circulated to a position of about ± １ ／ to 0H with respect to the powder surface height H. Is preferred. Circulation is usually performed by spraying.

The non-polymerizable hydrocarbon having a low boiling point used in the present invention has a large latent heat of vaporization, and when these are vaporized, the heat of polymerization can be effectively removed. Accordingly, by vaporizing such a low-boiling non-polymerizable hydrocarbon in the gas-phase polymerization reactor 3, the temperature control of the reaction system becomes easy.

The olefin polymer obtained as described above usually has a density measured by ASTM D 150 E of 0.880 to 0.970 g / cm ³ , preferably 0.9.
Is a 00~0.950g / cm ^3.

In this olefin polymer, as described above, in addition to the olefin, a structural unit derived from, for example, a polyene or the like is 10% by weight or less, preferably 5% by weight.
Below, particularly preferably, it can be contained in an amount of 3% by weight or less.

The olefin polymer produced by the polymerization method according to the present invention includes olefin homopolymer, ethylene α-
It may be an olefin copolymer or the like, and is not particularly limited, but is particularly preferably a linear low-density polyethylene.

The olefin polymer according to the present invention is obtained as granular particles, and has an average particle size of 250 to 3000 μm, preferably 400 to 1500 μm. Further, the olefin polymer obtained as described above, if necessary, a heat-resistant stabilizer, a weather-resistant stabilizer, an antistatic agent, an anti-blocking agent, a lubricant, a nucleating agent, a pigment, a dye, an inorganic or organic filler, and the like. It can also be blended.

As described above, in the present invention, the olefin is preliminarily polymerized in a large amount and continuously to obtain the prepolymerized catalyst (ii). When gas-phase polymerization is performed in the presence of such a prepolymerization catalyst (ii), an olefin polymer having excellent particle properties can be obtained, and a sheet-like polymer is not generated during polymerization, and the polymerization can be performed for a long time. It can be performed stably and continuously over a period.

In addition, the content of the fine powder particles is small in the prepolymerization catalyst (ii), and the scattering of the powder particles is reduced in the main polymerization using the catalyst. Furthermore, in the present invention, in the circulation step, when the liquid low-boiling non-polymerizable hydrocarbon is preferably circulated in the vicinity of the powder surface of the fluidized bed, when the low-boiling non-polymerizable hydrocarbon is vaporized, the heat of polymerization is efficiently reduced. The powdery particles can be prevented from scattering upward from the powder surface of the fluidized bed. This makes it possible to reduce or eliminate the deceleration range of the gas phase polymerization reactor.

[0090]

According to the olefin polymerization method of the present invention, in the prepolymerization step, a prepolymerization catalyst is prepared by continuously prepolymerizing or prepolymerizing a large amount of olefin on a solid catalyst. Supply to gas phase polymerization (main polymerization).

Such a prepolymerized catalyst can produce an olefin polymer having excellent particle properties in the main polymerization.
In particular, in the main polymerization using such a prepolymerization catalyst,
No sheet polymer is formed during the polymerization.

Further, by supplying the prepolymerized catalyst to the gas phase polymerization vessel together with the liquid low-boiling non-polymerizable hydrocarbon,
Since the hydrocarbon is easily vaporized, the dispersion of the prepolymerized catalyst in the gas phase polymerization vessel is improved, and the formation of a polymerized mass due to local polymerization can be prevented.

Therefore, the main polymerization can be performed stably and continuously for a long period of time. In addition, the content of the fine powder particles is small in the prepolymerization catalyst (ii), and the scattering of the powder particles is reduced in the main polymerization using the catalyst.
This makes it possible to reduce or eliminate the deceleration range of the reactor.

Further, in the present invention, in the main polymerization, a part of the low-boiling non-polymerizable hydrocarbon discharged from the gas phase polymerization vessel is liquefied and preferably circulated near the powder surface of the reaction system (fluidized bed). Let it.

In such a low-boiling non-polymerizable hydrocarbon,
The latent heat of vaporization is large, and when these are vaporized in the gas phase polymerization vessel, while exhibiting the effect of efficiently removing the heat of polymerization,
By spraying at such a position, an effect of contacting the powdery particles to be scattered from the fluidized bed and returning to the reaction system is exhibited.

Therefore, the main polymerization can be carried out effectively in terms of thermal efficiency, and the scattering of powder particles can be reduced. Therefore, the deceleration region of the reactor is reduced or, depending on the conditions, the deceleration region is not required. Is also possible. Also, it is not necessary to use a cyclone.

[0097]

EXAMPLES The present invention will be described below with reference to specific examples, but the present invention is not limited to these examples.

[0098]

Example 1 [Preparation of Catalyst] Silica 10 dried at 250 ° C. for 10 hours
kg in suspension with 154 liters of toluene,
Cooled down. Thereafter, 82.0 liters of a methylaminooxane toluene solution (Al = 1.33 mol / l) was added dropwise over 1 hour. At this time, the temperature in the system was kept at 0 ° C. Subsequently, the reaction was carried out at 0 ° C. for 30 minutes, and then 1.5 minutes.
The temperature was raised to 95 ° C. over time, and the reaction was carried out at that temperature for 20 hours. Thereafter, the temperature was lowered to 60 ° C., and the supernatant was removed by decantation. The solid component thus obtained was washed twice with toluene and then resuspended in 100 l of toluene. To this system, 24.0 liters of a toluene solution of bis (1,3-dimethylcyclopentadienyl) zirconium dichloride (Zr = 27.0 mmol / liter) was added dropwise at 80 ° C. over 30 minutes.
For 2 hours. Thereafter, the supernatant was removed and washed twice with hexane to obtain a solid catalyst containing 5.1 mg of zirconium per gram.

This catalyst was used as a propane suspension. [Gas Phase Polymerization] In a continuous polymerization apparatus comprising a pre-polymerizer 1 and a fluidized-bed gas-phase polymerizer 3 shown in FIG. 1, a tank-type pre-polymerizer 1 having a reaction volume of 100 liters was used.
The catalyst suspended in a small amount of propane was continuously supplied at a rate of 1.4 mmol / hr in terms of Zr atoms and at a rate of 10 mmol / hr of triisobutylaluminum, and at the same time, ethylene was fed at 5 kg / hr. , 1-hexene was supplied at 1 kg / hr. In order to adjust the intrinsic viscosity [η] of the copolymer formed in the prepolymerizer 1 to a desired value, H ₂ was continuously supplied to the prepolymerizer 1 at a rate of 8 liter / hr. Further, liquid propane containing 80 kg / hr of propane circulated by the pump 16 from the condensate drum 11 as a polymerization solvent for prepolymerization was continuously supplied to the prepolymerizer 1 at a rate of 100 kg / hr.

The polymerization conditions of the prepolymerizer were a pressure of 25 kg / cm ^2.
G, the concentration was 50 ° C., the residence time was 30 minutes, the density was 0.925 g / cm ^{3 in the} prepolymerizer, the intrinsic viscosity [η] = 2.1,
A predominantly spherical ethylene / 1-hexene prepolymer having an average particle diameter of 260 μm and a very good particle shape was continuously produced at a rate of 5.4 kg / hr.

This is equivalent to 21 g / g of the supplied solid catalyst.
This corresponds to pre-copolymerization at a rate of 6 g. The ethylene / 1-hexene copolymer produced by the pre-copolymerization passes from the pre-polymerizer 1 via the tube 2 to a reaction system 5 having a diameter of 100 cmφ.
The height was 180 cm, the fluidized bed capacity was 1400 liters, and the maximum diameter was 140 cmφ in the deceleration zone 3a.

That is, 155 kg / hr of ethylene and 20 kg / hr of 1-hexene corresponding to the amounts consumed in the gas phase polymerization were used.
, And hydrogen was further supplied from the tube 15 so that the H ₂ concentration in the reactor was 4 × 10 ⁻⁴ mole ratio with respect to ethylene.

The polymerization conditions of the gas phase polymerization vessel were as follows: pressure 20 kg / cm ²
G, the polymerization temperature was 75 ° C., the residence time was 3.0 hours, and the circulating gas linear velocity in the gas phase polymerization vessel was maintained at 60 cm / sec. The gas composition in the gas phase polymerization vessel is C ₂ ⁼ (ethylene) 2
9.0 mol%, C ₆ ⁼ -1 (1-hexene) 0.9 mol%, and propane 69.2 mol%.

A part of the fluidized bed circulating gas is withdrawn from the pipe 9 and propane containing a part of the olefin condensed in the condenser 10 is passed through the condensate circulating pump 16 and the pipe 13 for 150 minutes.
The powder was supplied at a rate of kg / hr in the vicinity of the powder surface of the fluidized bed of the gas phase polymerization reactor.

Further, propane containing a part of the condensed olefin was continuously supplied to the prepolymerizer 1 at a rate of 80 kg / hr through the condensate circulation pump 16. As a result, the polyethylene produced under the above conditions was extremely free of finely divided polyethylene having an MI (melt index) of 2.2 g / 10 min, a density of 0.910 g / cm ³ , an average particle size of 860 μm, and a bulk specific gravity of 0.48 g / cm ^3. A spherical copolymer having an excellent shape was continuously discharged from the tube 14 at a rate of 165 kg / hr.

A long-term continuous operation was carried out under the above conditions, but no polymer lumps were formed in the gas phase polymerization vessel, and the holes in the dispersion plate of the gas for gas phase flow were clogged.
Extremely stable operation was possible without generating or clogging lumps in the pipes, heat exchangers and the like in the first circulation step and the second circulation step.

This is because the solid catalyst is preliminarily polymerized with ethylene and 1-hexene in a large amount and continuously in the presence of a low boiling point solvent such as propane, whereby the solid catalyst is used as a nucleus to obtain a preparative particle having an extremely excellent particle shape. A polymer was formed, and the presence of finely divided particles in the gas phase polymerization vessel continued thereafter was extremely reduced. This is an effect of suppressing the generation of fine powder particles due to the collapse of the catalyst component in the form of a powder.

When the particle size distribution of the produced polyethylene was measured, the amount of the finely divided or finely divided polyethylene in the 60-mesh pass was very small, not more than 0.2% by weight.

Further, as a result of forming a film using the obtained polyethylene as a raw material, an excellent film free of fish eyes was obtained, which was an extremely effective method in terms of quality.

[0110]

Comparative Example 1 Using the catalyst obtained in Example 1, a prepolymer was continuously produced in a prepolymerizer 1 at a rate of 0.1 kg / hr at a rate of 4 g per 1 g of a solid catalyst. Gas phase polymerization was carried out under the same conditions as in Example 1 except for the above.

That is, as in Example 1, the catalyst suspended in propane was converted to a Zr atom using a device comprising a prepolymerizer 1 having a volume of 20 liters and a gas phase polymerization device 3 having a fluidized bed reaction volume of 1400 liters. Converted to 1.4 mmol / hr, triisobutylaluminum 15 mmol / hr
hr, the ethylene was continuously supplied to the prepolymerizer at a rate of 0.2 kg / hr, and 1-hexene was supplied at a rate of 0.04 kg / hr.

In order to adjust the intrinsic viscosity [η] of the copolymer produced in the prepolymerizer 1 to about 2.0 dl / g, H
_The required amount of ₂ was supplied. Liquid propane was supplied together with the Zr catalyst at a rate of 20 kg / hr as a polymerization solvent for prepolymerization.

The polymerization conditions of the prepolymerizer were the same as in Example 1, the pressure was 25 kg / cm ² G, the concentration was 50 ° C., the residence time was 30 minutes, the density was 0.928 g / cm ³ , the intrinsic viscosity [η] in the prepolymerizer. = 2.0 dl / g of the pre-copolymer
It was produced at a rate of kg / hr. The shape of the resulting pre-copolymer was relatively good spherical particles, but also partially contained a finely divided polymer.

The produced ethylene / 1-hexene precopolymer was continuously supplied from the prepolymerizer 1 via the pipe 2 to the gas phase polymerizer 3, and subsequently the gas phase polymerization was carried out under the same polymerization conditions as in Example 1. Continued.

That is, a pressure of 20 kg / cm ² G and a polymerization temperature of 7
5 ° C., residence time 3.0 hr, circulating gas linear velocity in the gas phase polymerization vessel 60 cm / sec, gas composition C in the gas phase polymerization vessel
Gas phase polymerization was carried out with ₂ ⁼ (ethylene) 29.0 mol%, C ₆ ⁼ -1 (1-hexene) 0.9 mol%, and propane 69.4 mol%, MI 2.1 g / 10 min, density 0 .910 g / cm
^3. Polyethylene having an average particle size of 830 µ was continuously obtained at a rate of 165 kg / hr.

Although the shape of the obtained polyethylene particles is relatively good in spherical shape, it contains a large number of irregular fine particles and fine powders. % By weight or more. As a result of observing the produced polyethylene, it was confirmed that fine powder particles were clearly produced in the gas phase polymerization vessel due to the collapse of the solid catalyst. The bulk specific gravity of the produced polyethylene was 0.39 g /
cm ³ was lower than that of Example 1.

Further, a long-term continuous operation was attempted under the above conditions, but a large number of polymer lumps and sheet-like lumps were found in the gas phase polymerization vessel. In addition, the amount scattered from the gas phase polymerization vessel into the circulation system increases, and the clogging of the pipes and heat exchanger tubes in the first and second circulation steps and the clogging of the holes in the dispersion plate for the flowing gas occur in a short time. They could only continue driving for a few days.

[0118]

Comparative Example 2 Using the catalyst obtained in Example 1, the intrinsic viscosity [η] of the preliminary copolymer produced in the preliminary
A copolymerized polyethylene of ethylene and 1-hexene was obtained by gas phase polymerization under the same apparatus and under the same polymerization conditions as in Example 1 except that dl / g was used.

Using the same apparatus as in Example 1 consisting of a prepolymerizer 1 having a volume of 100 liters and a gas phase polymerization vessel 3 having a fluidized bed reaction volume of 1400 liters, the catalyst suspended in propane was treated with Zr. 1.4 mmol / hr and 15 mmol / hr triisobutylaluminum in terms of atoms
, And 5 kg / hr of ethylene and 1 kg / hr of 1-hexene at the same time.

In order to adjust the intrinsic viscosity [η] of the copolymer produced in the prepolymerizer 1 to about 10.0, H ₂ was hardly supplied. The shape of the produced pre-copolymer was inferior to that of Example 1, and many fine powders and aggregated particles were observed.

The produced ethylene / 1-hexene pre-copolymer is supplied from the pre-polymerizer 1 through the pipe 2 to the vicinity of the powder surface of the fluidized-bed of the gas-phase polymerizer 3, and subsequently under the same polymerization conditions as in Example 1. Gas phase polymerization was continued.

That is, a pressure of 20 kg / cm ² G, a polymerization temperature of 75 ° C., a residence time of 3.0 hours, a circulating gas linear velocity of 60 cm / sec in a gas phase polymerization vessel, and a gas composition C ₂ ⁼
(ethylene) 29.0 mol%, C ₆ ⁼ -1 (1- hexene)
Gas phase polymerization was carried out with 0.9 mol% and propane 69.2 mol%, MI = 2.2 g / 10 min, density 0.910 g / cm ³ ,
Polyethylene having an average particle size of 830 μ was continuously obtained at a rate of 165 kg / hr.

The shape of the obtained polyethylene particles includes spherical particles, but contains many fine particles and fine powders, and also contains many large irregularly shaped particles. It contained 3.5% by weight or more of particulate polyethylene, and a large number of irregularly shaped 10-mesh-on coarse particles were also observed.

As a result of observing the produced polyethylene, it was confirmed that fine powder particles were produced due to the collapse of the solid catalyst and a large number of irregularly shaped aggregates were generated in the gas phase polymerization reactor.

Further, due to the deterioration of the particle shape,
The bulk density of ethylene is also 0.38 g / cm ^ThreeAnd compared with Example 1
It was clearly lower. Furthermore, long-term continuous operation under the above conditions
Was attempted, but the polymer mass or sheet mass was
Formation of a large amount of water
The amount of scatter increases, and the distribution of the first and second circulation steps
Blockage of tubes, heat exchanger tubes, holes in gas distribution plates
Clogging occurs in a short time, and operation can be continued for only a few days
Did not.

Further, a film was formed from the obtained polyethylene as a raw material.
Only poor quality was obtained.

[Brief description of the drawings]

FIG. 1 shows the process of the olefin polymerization method according to the present invention.

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yoshinori Morita 1-2-2, Waki, Waki-machi, Kuga-gun, Yamaguchi Prefecture Inside Mitsui Petrochemical Industry Co., Ltd. (56) References JP-A-4-91107 (JP) JP-A-57-155204 (JP, A) JP-A-56-34709 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08F 2/00-2/60 C08F 4/642

Claims (2)

(57) [Claims] An olefin is prepolymerized on a solid catalyst (i) containing a transition metal compound of Group IVB of the Periodic Table having a cyclopentadienyl skeleton [I] having a cyclopentadienyl skeleton.
i) is prepared, and the obtained prepolymerization catalyst (ii) is supplied into a gas phase polymerization reactor. [II] In a fluidized bed, which is a reaction system maintained in a fluidized state, a low boiling point non- A main polymerization step of vapor-phase polymerization or copolymerization of an olefin with the prepolymerization catalyst (ii) in the presence of a polymerizable hydrocarbon; [III] a low-boiling non-polymerizable hydrocarbon discharged from the upper part of the gas-phase polymerization vessel Part of which is circulated from below the gas phase polymerization reactor
A circulation step, and [IV] a second circulation step of liquefying a part of the low-boiling non-polymerizable hydrocarbon discharged from the upper part of the gas phase polymerization vessel and circulating it in the gas phase polymerization vessel, [III] and / or [IV] When the olefin supplied to the circulation step is subjected to gas phase polymerization, in the above [I] pre-polymerization step, the olefin having 2 to 1 carbon atoms is present in the presence of a liquid low-boiling non-polymerizable hydrocarbon.
8 is prepared by continuously pre-copolymerizing two or more olefins selected from the olefins of formula (8) to prepare a prepolymerized catalyst (ii) satisfying the following conditions. A method for polymerizing olefins, characterized by continuously feeding into a gas phase polymerization reactor together with hydrogen: olefin polymerization amount; 50 to 50 g / g of the solid catalyst (i)
1200 g, density: 0.880 to 0.970 g /
cm ³ , intrinsic viscosity [η]: 0.5 to 8 dl / g. 2. The method according to claim 1, wherein one of the olefins to be precopolymerized is ethylene.