JPH09302008A - Gas phase polymerization of olefins - Google Patents

Abstract

(57) [Summary] [Structure] In a method for vapor phase polymerization of olefins in a fluidized bed reactor, cooling the inner wall temperature of the reactor to a temperature below the dew point of the fluidized gas by a cooling tube attached to the outer wall of the reactor. Characteristic olefin gas-phase polymerization method. [Effect] When a polymer is produced in a fluidized bed reactor,
It is possible to carry out stable gas phase polymerization without generation of sheet-like lumps and adhesion of polymer particles to the reactor wall.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a process for vapor phase polymerization of olefins in a fluidized bed reactor. In more detail, a bulk polymer produced when continuously polymerizing and copolymerizing an olefin using a gas-phase fluidized bed reactor, particularly a gas of an olefin that can be stably produced without generating a sheet-like mass. It relates to a phase polymerization method.

[0002]

2. Description of the Related Art Conventionally, olefin polymers have been produced by solution, bulk, slurry or gas phase polymerization methods. In recent years, the activity of the catalyst has been remarkably improved, and a process which does not require a step of separating a catalyst residue from a produced polymer has been widely used. In particular, a method of vapor phase polymerization of an olefin in a fluidized bed reactor has industrial value. It is highly paid attention.

When producing polymers in a fluidized bed reactor,
Since it is difficult to remove the heat of polymerization compared to solution polymerization methods,
Due to the local accumulation of polymerization heat, the temperature inside the fluidized bed becomes unstable and a bulk polymer is formed, making it difficult to maintain the fluidized state.In addition, the generated bulk polymer blocks the extraction line of the product, so continuous In some cases, stable production could be difficult.

Japanese Unexamined Patent Publication (Kokai) No. 54-139983 discloses a method of removing heat of polymerization by providing an internal cooler in a fluidized bed reactor. There is a problem that there is no description, and the flow condition is disturbed by the internal cooler, and the polymerization reaction tends to become unstable.

JP-A-56-4608 discloses that an inert hydrocarbon compound having a carbon number of 3 or more is allowed to coexist in a liquid state in a polymerization reactor, so that a polymer for a polymerization reactor wall or other parts of the reactor is polymerized. It is disclosed to prevent electrostatic sticking of particles.

However, in the above-mentioned method, since a liquid substance exists in the polymerization reactor, there is a problem in that the measurement of the differential pressure gauge necessary for controlling the reaction is disturbed and the control of the polymerization reaction tends to be difficult. Further, in the copolymerization of ethylene with an olefin having a large number of carbon atoms, a part of the olefin or hydrocarbon is liquefied and introduced, so that the copolymerization becomes uneven, which is not preferable in terms of product characteristics.

Further, Japanese Patent Application No. 7-62009 describes a polymerization method in which the temperature of the inner wall of the reactor is cooled below the dew point of the fluidized gas in the fluidized bed gas phase polymerization. There is disclosed a method of preventing the formation of styrene and stably performing gas phase polymerization. An air cooling fan, a cooling jacket, etc. are illustrated as an apparatus which cools the reactor inner wall temperature. Since a fluidized bed gas phase polymerization reactor has devices such as a temperature sensor, a catalyst introduction line, and a polymer extraction line on the outer wall portion, it is necessary to install the above cooling device at a desired position of the polymerization reactor. Sometimes there were difficulties. Further, in the gas phase fluidized bed polymerization, the inner wall of the polymerization reactor is efficiently cooled depending on the attachment site of the polymer depending on the shape of the reactor, the injection method of the catalyst used, the particle shape of the prepolymer, etc. It can be difficult.

[0008]

OBJECTS OF THE INVENTION The present invention provides a method for preventing a bulk polymer from being generated in a conventional fluidized bed gas phase polymerization process and enabling a long-term stable polymerization reaction.

[0009]

DISCLOSURE OF THE INVENTION The present invention is a method for vapor phase polymerization of olefins in a fluidized bed reactor, wherein the temperature of the inner wall of the reactor is kept below the dew point of the fluidized gas by a cooling tube attached to the outer wall of the reactor. It relates to a gas phase polymerization method of an olefin, which is characterized by cooling.

[0010]

DETAILED DESCRIPTION OF THE INVENTION The olefin polymerization of the present invention is conducted continuously in the gas phase in a fluidized bed reactor. That is, a catalyst component, an olefin monomer, an inert gas, an additive, etc. are continuously introduced into a fluidized bed reactor, and polymerization is carried out while fluidizing catalyst particles and polymer particles by a gas phase component. In the continuous polymerization, the produced polymer is continuously or intermittently withdrawn from the reactor from the calming compartment in the upper part of the reactor, and the unreacted monomer gas is continuously discharged from the fluidized bed reactor. The unreacted monomer gas is preferably re-introduced into the fluidized bed reactor after removing the entrained fine powder polymer with a cyclone or the like, appropriately replenishing the olefin monomer and the like via a heat exchanger and a compressor through a circulation line. To be done.

Examples of the reactor used in the present invention include those disclosed in JP-A-58-201802, JP-A-59-126406, JP-A-2-233708, and JP-A-4-234409. The fluidized bed reactor described can be used.

In the present invention, in the method of continuously vapor-phase polymerizing an olefin in a fluidized bed reactor, the inner wall temperature of the fluidized bed reactor at the time of the polymerization is lower than the dew point of the fluidized gas, preferably 2 ° C. or more lower than the dew point. , More preferably than the dew point
Cool down at least 4 ℃. The inner wall of the fluidized bed reactor of the present invention can be cooled by a cooling tube attached to the outer wall of the reactor. In the gas-phase fluidized bed polymerization, since the attachment site of the polymer differs depending on the shape of the reactor, the method of injecting the catalyst used, the particle shape of the prepolymer, etc., there is no particular limitation on the attachment position of the cooling tube,
It can be embedded in the cylinder part of the reactor, usually at a height of about 1 to 2 times the reactor diameter from the bottom of the reactor, or in a part of the reactor such as the calming compartment above the reactor. it can.

As the cooling tube, a tube made of copper or the like having a good thermal conductivity and closely adhered to the outer wall of the reactor with heat-resistant heat transfer cement or the like can be preferably used. By flowing a coolant such as water through the cooling tube,
The inner wall of the reactor can be cooled.

In the present invention, a Ziegler type catalyst or a metallocene catalyst is used as the polymerization catalyst. The Ziegler type catalyst comprises a transition metal catalyst solid component and an organoaluminum compound.

The transition metal catalyst solid component is titanium,
Periodic table of vanadium, chromium, zirconium, etc. IV ~
Group VI transition metal compounds can be used, and high activity catalysts obtained by supporting these compounds on a carrier such as a magnesium compound such as magnesium chloride or an inorganic oxide such as silicon dioxide, alumina, or zirconia are preferable. Used for.

As a method for producing these catalyst solid components, there are disclosed in Japanese Patent Laid-Open Nos. 59-8706, 59-22907, and 59-2.
2908 publication, 59-64611 publication, 59-71309 publication,
60-42404 JP, 60-133011 JP, 60-215006 JP, 62-232405 JP, 62-297304 JP, JP 1-256502 JP, JP 1-289809 JP, JP-A-3-81
JP 303-88808 JP, JP 3-93803 JP, JP 56-18132 JP, JP 56-15807 JP,
Japanese Patent Publication No. 61-50964, Japanese Patent Publication No. 61-363, Japanese Patent Publication No. 62
The method proposed in -56885 publication can be adopted.
As a typical production method, a method of treating a magnesium chloride carrier obtained by reacting a specific organomagnesium compound, a chlorinated organic compound and an electron addition donor under specific conditions with titanium tetrachloride, and the like can be mentioned.

Examples of the transition metal compound include halides of transition metals of group IV to VI of the periodic table such as titanium, vanadium, chromium, zirconium and hafnium, hydrocarbyl oxyhalides, hydrocarbyloxyhalides, hydrocarbyloxyhydrocarbyl compounds and hydrocarbyl. Examples thereof include halides, hydrocarbyloxyhydrocarbyl halides, and the like.

Of these, titanium compounds can be preferably used. Specific examples thereof include methoxytrichlorotitanium, dimethoxydichlorotitanium, trimethoxychlorotitanium, ethoxytrichlorotitanium, diethoxydichlorotitanium, propoxytrichlorotitanium, dipropoxydichlorotitanium, butoxytrichlorotitanium, dibutoxydichlorotitanium, phenoxy. Trichlortitanium, diphenoxydichlorotitanium, methoxytribromotitanium,
Examples thereof include phenoxytribromotitanium, methoxytriiodotitanium, phenoxytriiodotitanium, tetrachlorotitanium, tetrabromotitanium, tetraiodotitanium, tetramethoxytitanium, tetraethoxytitanium, and tetrapropoxytitanium.

Examples of the organoaluminum compound used together with the catalyst solid component include trialkylaluminum, dialkylaluminum halide, dialkylaluminum hydride and alkylalumoxane. Specific examples thereof include trimethyl aluminum, triethyl aluminum, tributyl aluminum, triisobutyl aluminum, trihexyl aluminum,
Examples include trioctylaluminum, diethylaluminum chloride, diethylaluminum hydride, isoprenylaluminum, and methylalumoxane.

Various electron donors may be further added to the above polymerization catalyst system. As the electron donor, organic acid ester, inorganic acid ester, acid halide, ether, acid amide, N, N-dialkyl acid amide, amine, nitrile, acid anhydride, silane compound, ketone, alcohol, aldehyde, carboxylic acid, Isocyanate or the like can be used. A silane compound is particularly preferable.

As the metallocene catalyst, there can be mentioned IV of the periodic table.
Alternatively, a combination of a metallocene compound of a group V transition metal with an organoaluminum compound and / or an ionic compound is used.

As the transition metal of Group IV or V of the periodic table,
Titanium (Ti), zirconium (Zr), hafnium (H
f) and vanadium (V) are preferred.

The metallocene compound means at least one cyclopentadienyl group and a substituted cyclopentadienyl group (for example, an alkyl-substituted cyclopentadienyl group such as methyl, dimethyl and pentamethyl, an indenyl group,
Fluorenyl group) as a ligand, or a cyclopentadienyl group having a hydrocarbyl group (eg, an alkylene group or a substituted alkylene group) or a hydrocarbyl silicon (eg, a silanylene group, a substituted silanylene group, a silaalkylene group, Cross-linked by silaalkylene) or the like, and further, cyclopentadienyl group is oxygen,
Those cross-linked to nitrogen and phosphorus atoms (for example, oxasilanylene group, substituted oxasilanylene group, oxasilaalkylene group, substituted oxasilaalkylene group, aminosilyl group,
Any known metallocene compound having a monosubstituted aminosilyl group, a phosphinosilyl group, or a monosubstituted phosphinosilyl group) as a ligand can be used.

Specific examples thereof are disclosed in JP-A-58-19309.
No. 60-35006, No. 61-130314, No. 61
JP-A-264010, JP-A-61-296008, JP-A-63-222177, JP-A-63-251405, JP-A-1-66214,
Nos. 1-74202, 1-275609, 1-301704, 1-319489, 2-41303 and 2-131488
Publication Nos., 3-12406, 3-139504, 3-17
9006 gazette, the same 3-185005 gazette, the same 3-18809 gazette, the same
No. 3-197514, No. 3-207703, No. 5-2009013, Japanese Translation of PCT International Publication No. 1-501950, No. 1-502036, and
Examples thereof include those described in JP-A-5-505593.

In the present invention, as catalysts other than the above, Japanese Patent Laid-Open Nos. 61-130314 and 61-264010,
JP 63-142004, JP-A 1-129004, 1-301704
Gazette, Gazette 2-75605, Gazette 3-12406, 3-12
Nos. 407, 4-227708, 4-268308,
Examples thereof include metallocene compounds described in JP-A Nos. 4-300887 and 6-25343.

The organoaluminum compound used in combination with the metallocene compound in the present invention has the general formula (-
Al (R) O-) _{n represents} a linear or cyclic polymer (R
Is a hydrocarbon group having 1 to 10 carbon atoms, including those partially substituted with a halogen atom and / or an RO group. n is the degree of polymerization and is 5 or more, preferably 10 or more), and specific examples include methylalumoxane, ethylalumoxane, and isobutylethylalumoxane, each of which is a methyl, ethyl, or isobutyl group. Can be

The ionic compound is represented by the general formula: C ⁺ A
^- , C ⁺ is an oxidizing cation of an organic compound, an organometallic compound, or an inorganic compound, or a Bronsted acid comprising a Lewis base and a proton, and reacts with an anion of a metallocene ligand to form a metallocene cation. Can be generated.

A ⁻ is a bulky, non-coordinating anion and can stabilize the metallocene cation without coordinating to the metallocene. As specific examples thereof, those described in JP-A-4-25711, JP-A-4-305585, JP-A-5-507756, and JP-A-5-502906 can be used.

Particularly, an ionic compound of a tetrakis (pentafluorophenyl) borate anion and a triphenylcarbonium cation or a dialkylanilinium cation is preferable. These ionic compounds can be used in combination with the above-mentioned organoaluminum compound.

The above-mentioned polymerization catalyst can be used by supporting it on an inorganic compound or an organic polymer compound. As the inorganic compound as the carrier, inorganic oxides, inorganic chlorides and inorganic hydroxides are preferable, and those containing a small amount of carbonate and sulfate can also be used. Particularly preferred are inorganic oxides, such as silica, alumina, magnesia, titania, zirconia, and calcia.

Examples of the organic polymer compound include α-olefin homopolymers, α-olefin copolymers, acrylic acid, methacrylic acid, vinyl chloride, vinyl alcohol, styrene, divinylbenzene, etc., which have functional groups by chemical modification of ethylene, propylene, polybutene, etc. The homopolymers and copolymers thereof, as well as their chemically modified products can be mentioned. As these organic polymer compounds, spherical fine particles having an average particle diameter of 5 to 250 μm are used.

The olefin used in the present invention is
Linear α such as ethylene, propylene, butene-1, pentene-1, 4-methylpentene-1, hexene-1, octene-1
-Cyclic α-olefins such as olefins, cyclopentene and cyclohexene.

The method of the present invention can be suitably used for homopolymerization of ethylene or propylene and copolymerization of ethylene or propylene with other α-olefins. In particular, by copolymerizing ethylene with another α-olefin,
It can be suitably used for a method for producing linear low-density polyethylene (LLDPE). The α-olefin used for copolymerization with ethylene, propylene, butene-1, pentene-1, hexene-1, 4-methylpentene-1,
Octene-1 and so on. Among them, olefins having 4 or more carbon atoms can be preferably used.

The circulating gas may contain an inert gas such as hydrogen or nitrogen as a molecular weight modifier.

In the gas phase polymerization method of the present invention, it is preferable that the circulating gas contains saturated hydrocarbon, preferably saturated hydrocarbon having 4 to 6 carbon atoms. As a saturated hydrocarbon, a small molecular weight such as propane is not effective unless it is introduced in a large amount, and a saturated hydrocarbon having a high molecular weight is difficult to remove from the product powder. Carbon number 4
Examples of saturated hydrocarbons of No. 6 to 6 are butane, isobutane,
Examples include n-pentane, i-pentane, hexanes and mixtures thereof.

The amount of the saturated hydrocarbon having 4 to 6 carbon atoms and the total amount of the olefin monomer having 4 or more carbon atoms in the circulating gas are
1.0 mol% or more is preferable, and 1.0 to 15 mol% is more preferable. If it is less than the above range, the effect is small, and if it is too large, the dew point becomes high.

As the polymerization conditions, the polymerization temperature is usually 5 to 1
00 ℃, preferably 60 ~ 95 ℃, the atomic ratio of transition metal in the solid catalyst to the organoaluminum compound (Al / M) is 1 ~ 1000
0, the polymerization pressure can usually be carried out under conditions of atmospheric pressure to 100 kg / cm ² · G.

Further, the purpose of improving the polymerization activity, maintaining the shape of the produced polymer, facilitating the introduction of the catalyst into the polymerization reactor, preventing the catalyst from adhering to the polymerization reactor, improving the fluidity in the fluidized bed reactor, etc. For example, after preliminarily polymerizing a certain amount of an olefin or an olefin and another olefin, the prepolymer can be used in the main polymerization as a catalyst. Prepolymerization is, for example, in a slurry method in an inert hydrocarbon solvent, usually, the polymerization temperature 5 ~ 80 ℃, preferably 10 ~ 80 ℃, polymerization time
It is carried out for 5 to 60 minutes under the condition that 1 to 100 g of the polymer is obtained per 1 mg atom of the transition metal in the catalyst solid.

An embodiment of the present invention will be schematically described with reference to FIG. The gas phase reaction mixture is polymerized in the gas phase fluidized bed portion 1 of the reactor, withdrawn from the top of the calming compartment 3 at the top of the reactor, through a heat exchanger 6 and a compressor 7 through a circulation line 5. It is reintroduced from the bottom of the reactor. The supplementary supply material is supplied from the material supply line 8. A prepolymer preliminarily polymerized with a small amount of olefin in a catalyst or another container is supplied from a supply line 9. The produced polymer is continuously or intermittently withdrawn from the reactor by the withdrawal line 10 so that the height of the gas phase fluidized bed portion becomes constant.

[0040]

【Example】

Example 1 (Synthesis of solid carrier) In a 100 L reactor pre-filled with nitrogen equipped with a mechanical stirring system and a double jacket,
Charge 26.2 L of toluene and 1.2 mol of triethylaluminum, and while maintaining the temperature at 26 ° C, use tert-butyl alcohol.
1.2 mol was added. To this mixture was added 4.02 L of diisoamyl ether solution containing 6 mol of n-butyl magnesium chloride. 6.6 mol of tert-butyl chloride was added dropwise over 30 minutes while raising the temperature to 40 ° C. In addition, 40
The reaction was carried out for 5 hours while maintaining at ℃. The obtained carrier solid was spherical particles having a relatively narrow distribution with a particle size (radius) of 30-40 μm.

(Synthesis of solid catalyst) 500 g of the obtained carrier was slurried in 7.5 L of toluene, and 7.5 M of methyltriethoxysilane as an electron donor was added at 40 ° C.
The mixture was stirred at 60 ° C. for 60 minutes, 10 mol of tetrachlorotitanium was added, and the mixture was stirred at 40 ° C. for 60 minutes. Then, the solid was separated by filtration, washed 3 times with 5 L of toluene and once with 5 L of heptane, and the solid was dried. The Ti content of the obtained spherical solid is 0.
The content was 61% and the Mg content was 15.7%.

(Preliminary Polymerization) 200 L filled with nitrogen gas
80 L of n-heptane was charged to the autoclave, and 0.75 mol of tri-n-octylaluminum, 0.25 mol of triethylaluminum and the above catalyst solid (titanium content of 0.25 mol) were added. After hydrogen gas of 1.5 kg / cm ² · G was injected under pressure, the temperature was raised to 60 ° C. to start polymerization. 67 during polymerization
Keep at 80 ℃ and introduce ethylene at 100L / min.
Polymerization was carried out until 40 g of prepolymer was produced per M 2.

(Gas Phase Polymerization) Using the fluidized bed reactor shown in FIG. 1, a cooling tube was attached to a position at a height of 1 to 1.5 times the diameter of the reactor from the bottom of the reactor, and Copolymerization of ethylene and butene-1 was performed while cooling the inner wall 5 ° C below the dew point of the flowing gas. As the polymerization catalyst, a solid catalyst prepared by the method described above and a catalyst system composed of triethylaluminum were used. The composition of the flowing gas and the polymerization conditions are summarized in Table 1. Polymerization could be carried out stably, and no adhesion of polymer particles to the reactor wall was observed.

Examples 2 and 3 Under the conditions shown in Table 1, polymerization was carried out in the same manner as in Example 1. Polymerization could be carried out stably, and no adhesion of polymer particles to the reactor wall was observed.

Comparative Example 1 Polymerization was carried out in the same manner as in Example 1 except that the inner wall of the reactor was not cooled. Sheet-like lumps were formed, the polymerization could not be carried out stably, and adhesion of polymer particles to the reactor wall was observed.

[0046]

[Table 1]

[0047]

INDUSTRIAL APPLICABILITY According to the present invention, when a polymer is produced in a fluidized bed reactor, it is stable without generation of sheet-like lumps and adhesion of polymer particles to the reactor wall. Gas phase polymerization can be carried out.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of the present invention. Explanation of symbols 1 ... Gas phase fluidized bed part of reaction 2 ... Fluidized bed cylinder 3 ... Calming compartment 4 ... Fluidization grid 5 ... Circulation line 6 ... Heat exchanger 7 ... Compressor 8 ... Raw material supply line 9 ... Preliminary polymer supply line 10 ... Polymer extraction line 11 ... Cooling tube

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yuji Yano 1-8-8 Goi Minamikaigan, Ichihara City, Chiba Ube Industries Ltd. Chiba Factory

Claims (1)

[Claims] 1. A method of vapor-phase polymerizing olefins in a fluidized bed reactor, characterized in that the temperature of the inner wall of the reactor is cooled to below the dew point of the fluidized gas by a cooling tube attached to the outer wall of the reactor. Gas phase polymerization method.