JP2000143706A - Production of alpha-olefin polymer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing an α-olefin polymer capable of improving catalyst efficiency. SOLUTION: This method for producing an α-olefin polymer comprises subjecting an α-olefin to slurry polymerization or bulk polymerization in the presence of a stereoregular catalyst using a polymerizer 1 equipped with a multi-impeller stirrer, and removing generated polymerization heat by the use of latent heat caused by vaporization of a vaporizable substance. Therein, the polymerization operation is carried out under conditions that a superficiality- based vaporizing linear velocity of the vaporizable substance in a stirring tank is in a range of 1.0-4.0 cm/sec, a bubble content of the vaporizable substance in the slurry in the polymerizer 1 is <=30 vol.%, and a ratio of a stirring revolution speed to a minimum stirring revolution speed is >=0.8. The minimum stirring revolution speed is defined as a speed required for keeping a ratio, i.e., a ratio of a solid particle concentration in the slurry sampled at a position of 0.8-1.0 to a solid particle concentration in the slurry sampled at a position of 0-0.1, constant, when heights of the sampling positions are measured from the lower end of the straight body of the polymerizer 1, and given in figures divided by a height of the liquid level of the polymerizer 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to an α-
The present invention relates to a continuous production method in slurry polymerization or bulk polymerization of an olefin polymer, and more particularly to a continuous production method of an α-olefin polymer in which heat of reaction generated in the polymerization of α-olefin is removed by utilizing latent heat of evaporation of an evaporable substance.

[0002]

2. Description of the Related Art α in slurry polymerization or bulk polymerization
-The types of reactors for continuous production of olefin polymers are roughly classified into a double tube type such as a loop type reactor and a vertical cylindrical stirring tank type. Methods for improving the productivity of the reactor include (1) a method of reducing the reactor volume by operating the solid particles in the slurry inside the reactor at a higher concentration, and (2) a residence time of the stereoregular catalyst. There is a method to reduce the reactor volume by lowering the reactor volume. However, in the case of the latter method (2), generally, if the residence time of the stereoregular catalyst is reduced, the efficiency of the catalyst (the production amount of α-olefin per unit catalyst) is lowered. It is desirable to reduce the reactor volume by operating the solid particles at a higher concentration.

In the case of a loop reactor, in order to maintain the operation performance of a slurry circulation pump for circulating the slurry inside the reactor, the upper limit of the solid particle concentration in the slurry inside the reactor is limited to a stirred tank reactor. It is generally lower than. In addition, heat removal equipment for removing the heat generated from the slurry circulation pump in the case of the loop type reactor or the heat generated by stirring in the case of the stirred tank type reactor is required along with the reaction heat generated by the polymerization. . As a heat removal method, a jacket is attached to the outside of the loop reactor or the stirring tank, or a reactor in which a plurality of heat removal coil-type baffles are disposed inside the reaction tank or the slurry of the stirring tank is circulated. It is typically circulated externally by a pump or the like, and the circulation system is provided with equipment for heat removal such as a multi-tube heat exchanger.

[0004] For example, in the case of a stirred tank type reactor, a heat removal facility utilizing sensible heat, in which a jacket is attached to the outside and a plurality of heat removal coil type baffles are provided inside, and an α-olefin monomer is provided. An effective method is to evaporate an evaporating substance such as a solvent or a hydrocarbon-based solvent (dispersion medium) in the reactor and use heat removal equipment utilizing the latent heat of evaporation in combination.
Generally, a reflux condenser that can cool, condense and liquefy evaporated gas and return it to the reactor is used in a reactor that utilizes latent heat of evaporation. In the above method for producing an α-olefin polymer by slurry polymerization or bulk polymerization, it is necessary to improve the capacity of the above-mentioned heat removal equipment in order to improve the productivity of the reactor.

A general method for improving the heat removal capacity of a heat removal facility is to increase the heat transfer area of a heat exchanger of the heat removal facility. For equipment that removes heat using sensible heat in a loop type reactor or a reactor equipped with a jacket outside the stirring tank or with multiple heat removal coil type baffles inside the reaction tank, It is difficult to increase the heat transfer area of the heat removal equipment without changing the reactor volume because the heat removal equipment is attached to itself.

When the slurry in the stirring tank is externally circulated by a circulation pump or the like, and a heat removal system with equipment for heat removal such as a multi-tube heat exchanger is used in the circulation system, the volume of the reactor is reduced. Although it is possible to improve the productivity without changing the slurry pump, the upper limit of the solid particle concentration in the slurry inside the reactor as in the loop reactor is not used because the slurry pump is used. It needs to be lower than a stirred tank type reactor.

A multi-tube heat exchanger provided in the slurry circulation system is generally 50 mm in diameter in order to prevent problems such as adhesion and blockage due to reaction of the slurry to be handled. The one having the above inner diameter is used, and the heat transfer coefficient is 200 to 300 Kcal / m ² / ° C.
/ H). The method of increasing the heat transfer area of the heat exchanger in order to increase the heat removal capacity is disadvantageous industrially because the volume of the heat exchanger becomes excessively large. Furthermore, since the slurry circulates in the tube, it is necessary to circulate at a speed higher than the general slurry flow rate in order to smoothly transport the solid particles in the slurry, and it is necessary to improve the transport capacity of the slurry circulation pump, Further, the slurry pump may need to have a capacity exceeding the industrial production limit.

Further, in the case of a reactor using a stirring tank by a method utilizing latent heat of evaporation by evaporation of an evaporating substance such as an α-olefin monomer or a hydrocarbon solvent (dispersion medium), the volume of the reactor is not changed. It is possible to improve the productivity of the reactor, and the inside diameter of the tube used for the multi-tube heat exchanger attached to the heat removal system also has a very high risk of adhesion and blockage as in the aforementioned slurry cooler. Since it is small, a tube having a small diameter of 15 to 25 mm can be used, and the heat transfer coefficient is 400 to 600 Kcal / m ² / ° C./h.
When the heat transfer area of the heat exchanger is increased in comparison with the slurry cooler, the heat removal method is most suitable for improving the productivity of the reactor without increasing the volume of the heat exchanger. I can say.

As described above, a continuous method for producing an α-olefin polymer by slurry polymerization or bulk polymerization of a heat removal system utilizing latent heat of vaporization due to evaporation of a vaporized substance is industrially suitably used. The stirring tank of the above-described method utilizing the evaporation of an evaporating substance such as an α-olefin monomer or a hydrocarbon solvent (dispersion medium) is generally called a gas-liquid-solid three-phase aeration stirring tank. It is known to use a plurality of turbine type stirring blades. Further, in order to improve the mixing performance of the slurry, the discharge flow generated from the turbine type blade is directed upward or downward with the rotation of the stirring shaft in order to improve the mixing performance of the slurry. What is inclined 30 to 60 degrees with respect to the stirring axis is preferably used.

When a gas is generated by evaporating the evaporating substance, the generated gas passes through the slurry portion of the stirring tank, and rises to the gas phase portion at the top of the stirring tank, which does not substantially hold slurry. When a gas is mixed in the slurry, the force applied by the stirring blade to the slurry (that is, the stirring power) decreases, and as a result, the uniform mixing performance of the slurry decreases. When the uniform mixing performance of the slurry is reduced, a layer having a high solid particle concentration is formed at the lower portion of the slurry layer, and a layer having a low solid particle concentration is formed at the upper portion.

Generally, the slurry is withdrawn from the reactor from the lower part of the straight body of the reactor or the bottom of the reactor in many cases, and the decrease in the uniform mixing performance of the slurry is caused by the accumulation of solids in the upper part of the reactor. The amount will be reduced and thus the actual residence time of the catalyst will be reduced, reducing the efficiency of the catalyst. Further, when the gas passage amount is increased or the stirring rotation speed is low, the suspension of the solid particles in the slurry is inhibited,
This may cause a sedimentation layer to be formed at the bottom of the stirring tank, or the formation of giant particles due to agglomeration between the particles, and the inhibition of continuous production such as adhesion and blockage.

[0012] The phenomenon of lowering the uniform mixing performance of the slurry and obstructing the floating of the solid particles is caused by the superficial gas flow rate (U) based on the superficial tower obtained by dividing the amount of gas passing through the slurry layer by the sectional area of the stirring tank.
g), and the weight-based solid particle concentration (Ws) in the slurry and the average particle diameter of the solid particles (d)
p), the density of solids and liquids in the slurry (ρs and ρ
l), the kinematic viscosity (νl) of the liquid, the mounting position of the stirring blade disposed at the bottom of the stirring tank, and the dimensional ratio (stirring blade diameter / stirring tank diameter). The above-mentioned phenomenon tends to be eliminated by increasing the number of rotations of stirring, but the power required for stirring increases, which is not industrially preferable. Also,
Increasing the rotation speed of the stirring increases the gas content of the slurry. In the liquid phase portion of the stirring tank, since the slurry does not substantially exist in the portion occupied by the gas, when the stirring tank is used with the same liquid amount, the amount of retained solid decreases as described above, and the efficiency of the catalyst decreases. Will be.

[0013]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a slurry polymerization or bulk polymerization of α-olefins in which all or part of the reaction heat generated in the reaction is subjected to α-olefins or hydrocarbons. A reaction tank having a heat removal facility for removing an evaporant such as a system solvent (dispersion medium) by evaporation is used, and sedimentation and separation of solid particles in the slurry in the reaction tank are prevented to improve the uniform mixing performance of the slurry and to evaporate. An industrially advantageous α- is that it is possible to increase the efficiency of the catalyst by reducing the content of gas generated in the slurry due to the evaporation of the substance and substantially increasing the amount of solid particles retained in the reactor. An object of the present invention is to provide a method for producing an olefin polymer.

[0014]

Means for Solving the Problems The present invention has been made as a result of intensive studies to achieve the above object,
Using a polymerization tank equipped with multi-stage stirring blades, α-olefins are subjected to slurry polymerization or bulk polymerization in the presence of a stereoregular catalyst, and the generated heat of polymerization is removed by using latent heat due to evaporation of evaporating substances. In the method for producing an α-olefin polymer described above, the evaporation linear velocity (Ug) of the evaporating substance based on the empty tower in the stirring tank is in the range of 1.0 to 4.0 cm / sec, and the The bubble content of the evaporating substance [bubble volume / (bubble volume + slurry volume)] is 3
0% by volume or less and 0.8 to the liquid level height (H) in the polymerization tank with respect to the lower end of the straight body of the polymerization tank.
The solid particle concentration in the slurry at the
Minimum stirring rotation speed (Nusg) required to make the ratio of the solid particle concentration in the slurry at a position of ~ 0.1 constant.
The present invention provides a method for producing an α-olefin polymer, wherein the method is operated at a stirring speed of 0.8 or more.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION According to the present invention, an α-olefin is subjected to slurry polymerization or bulk polymerization in the presence of a stereoregular catalyst using a polymerization tank provided with multi-stage stirring blades. In the present invention, as an α-olefin used as a raw material, one having 2 to 18 carbon atoms, particularly one having 2 to 8 carbon atoms, for example, ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-octene and the like Can be mentioned. This α
-Olefin polymerization, the stereoregular catalyst in the polymerization tank, or various components constituting the same, for example, a solid catalyst component,
The reaction is carried out by continuously supplying a cocatalyst, an electron-donating compound as required, or a contact product thereof, an α-olefin, and if necessary, hydrogen.

The stereoregular catalyst used in the present invention comprises a solid catalyst component, an organoaluminum compound and, if necessary, an electron donating compound. Here, the term “consisting of” includes those containing various suitable components in addition to the above main components. The stereoregular catalyst according to the present invention has essentially no difference in solid catalyst components from conventional stereoregular catalysts of this kind. Stereoregular catalysts comprising a solid catalyst component, an organoaluminum compound and, if necessary, an electron donating compound are known (for example, JP-A-56-811, JP-A-58-83006, JP-A-58-83006).
-218507, JP-A-6-25338, JP-A-5
7-63311, JP-A-61-213208, JP-A-62-187706, JP-A-5-331233,
JP-A-5-331234, JP-A-63-289004
JP-A-1-319508, JP-A-52-9870
6, JP-A-1-54007 and JP-A-3-7
No. 2503).

The solid catalyst component used in the present invention contains magnesium, titanium, halogen, and an electron donating compound. Magnesium in the solid catalyst component is
Magnesium halides, such as magnesium chloride, magnesium bromide, magnesium iodide, magnesium fluoride; alkoxy, such as methoxy magnesium chloride, ethoxy magnesium chloride, isopropoxy magnesium chloride, butoxy magnesium chloride, hexoxy magnesium chloride, octoxy magnesium chloride Magnesium halide; allyloxy magnesium halide such as phenoxy magnesium chloride and methylphenoxy magnesium chloride; alkoxy such as methoxy magnesium, ethoxy magnesium, isopropoxy magnesium, n-butoxy magnesium, n-octoxy magnesium and 2-ethylhexoxy magnesium Magnesium; Ants such as phenoxymagnesium and methylphenoxymagnesium Alkoxy magnesium; magnesium laurate, can be obtained from such carboxylates of magnesium such as magnesium stearate. In addition, these magnesium compounds may be used alone or as a mixture.

The titanium in the solid catalyst component is usually Ti (O
R)_gX_4-g(R is a hydrocarbon group, X is a halogen, g is
A tetravalent titanium compound represented by the formula: 0 ≦ g ≦ 4)
Object, specifically, TiCl_Four, TiBr_Four, TiI_FourWhat
Which titanium tetrahalide; Ti (OCH_Three) C
l_Three, Ti (OC_TwoH_Five) Cl_Three, Ti (On-C_Four
H ₉) Cl_Three, Ti (OiC_FourH₉) Cl_Three, Ti
(OCH_Three) Br_Three, Ti (OC_TwoH_Five) Br_Three, Ti
(On-C_FourH₉) Br_Three, Ti (OiC
_FourH₉) Br_ThreeTrihalogenated alkoxy titers such as
, Ti (OCH_Three)_TwoCl _Two, Ti (OC_TwoH_Five)_Two
Cl_Two, Ti (On-C_FourH₉)_TwoCl_Two, Ti (O
-Ic_FourH₉)_TwoCl_Two, Ti (OCH_Three)_TwoB
r_Two, Ti (OC_TwoH_Five) _TwoBr_Two, Ti (On-C
_FourH₉)_TwoBr_Two, Ti (OiC_FourH₉)_TwoBr_Two
Dihalogenated alkoxytitanium such as Ti (OC
H_Three)_ThreeCl, Ti (OC_TwoH_Five)_ThreeCl, Ti (O-
n-C_FourH₉)_ThreeCl, Ti (OiC_FourH₉)_ThreeC
1, Ti (OCH_Three)_ThreeBr, Ti (OC_TwoH_Five)_ThreeB
r, Ti (On-C_FourH₉)_ThreeBr, Ti (O-i-
C_FourH₉)_ThreeMonohalogenated alkoxy titers such as Br
, Ti (OCH_Three)_Four, Ti (OC_TwoH_Five)_Four, Ti
(On-C_FourH₉)_Four, Ti (OiC_FourH₉)_Four
Such as tetraalkoxy titanium; or a mixture thereof
Or aluminum compound and silicide
Compounds, sulfur compounds, other metal compounds, hydrogen halides,
By mixture with halogen, etc., halogen is one of the above.
General formula Ti (OR)_gX_4-g(R is a hydrocarbon group, X is halo
And g represents a number satisfying 0 ≦ g ≦ 4)
Titanium compounds, hydrogen halides, halogens, etc.
It is common to introduce it.

As the electron donating compound in the solid catalyst component, there can be used a generally known compound used for producing such a solid catalyst component. Generally, oxygen-containing compounds and / or nitrogen-containing compounds are preferred. Examples of the oxygen-containing compound generally include ethers, ketones, esters, and alkoxysilanes. Examples of the nitrogen-containing compound include amines, amides, and nitroso compounds.

As the organoaluminum compound which is a cocatalyst of the stereoregular catalyst, any suitable one can be used. Specifically, (a) trialkyl aluminum,
For example, each alkyl group has 1 to 12 carbon atoms, such as trimethylaluminum, triethylaluminum, tri-n-propylaluminum, triisobutylaluminum, trihexylaluminum, trioctylaluminum, tridecylaluminum, tridodecylaluminum, (B) Halogen-containing organoaluminum compounds, specifically those in which one or two of the above alkyl groups of trialkylalnium are substituted with halogen, for example, chlorine, bromine, etc., for example, diethylaluminum chloride, ethylaluminum Sesquichloride, (c) a hydride-containing organoaluminum compound, specifically one in which one or two of the alkyl groups of the above trialkylaluminum are substituted with hydrogen, for example, diethylaluminum hydride Chloride, (including aryloxy group) (d) alkoxide-containing organic aluminum compound, one or two alkoxy groups of the alkyl group specifically above trialkylaluminum, especially 1 carbon atoms
Dimethylaluminum methoxide, diethylaluminum methoxide, diethylaluminum ethoxide, diethylaluminum phenoxide, (e) aluminoxane (also referred to as alumoxane), specifically, an alkyl group having a carbon atom Alkyl aluminoxanes having the formulas 1 to 12, such as methylaluminoxane, ethylaluminoxane, and isobutylaluminoxane, can be exemplified. Also, a plurality of these can be used within each group and / or between each group.

The amount of the organoaluminum compound used is not particularly limited. Usually, the molar ratio of aluminum in the organoaluminum compound to titanium in the solid catalyst component is from 0.1 to 10,000, preferably from 10 to 10,000. 500
0, more preferably 50 to 2,000. The electron-donating compound used as necessary also
Those used in this type of stereoregular catalyst can be used. In the present invention, oxygen-containing compounds and / or nitrogen-containing compounds can be mentioned as preferred.

Examples of the nitrogen-containing compound include triethylamine, ethylenediamine, diisopropylamine, di-t
-Butylamine, pyridine, piperidine, 2,2,6
Examples thereof include amines such as 6-tetramethylpiperidine and derivatives thereof, and nitroso compounds such as tertiary amines, pyridines, and N-oxides of quinolines. As the oxygen-containing compound, generally, ethers,
Ketones, esters and alkoxysilanes can be mentioned.

(A) ethers include ether oxygen
The total number of carbon atoms is 2 to 18
Preferably about 4-12, ether ether
What is inside it, for example, diethyl ether, di
Propyl ether, diethylene glycol dimethyle
Ter, propylene glycol dimethyl ether, ethyl
Oxide, tetrahydrofuran, 2,2,5,5-te
Tramethyltetrahydrofuran, dioxane, etc.
(B) ketones which bind to ketone carbonyl groups
Hydrocarbon residue has a total carbon number of about 2 to 18, preferably
About 4 to 12 such as acetone, diethyl keto
, Methyl ethyl ketone, acetophenone, etc.
(C) As esters, the carboxylic acid moiety is aryl
Or aralkyl carboxylic acid (aryl group or aryl)
Is phenyl or lower (C₁~ C _FourDegree) Archi
And / or lower (C₁~ C_FourDegree) alkoxy
Substituted phenyl is preferred, and the alkyl moiety of the aralkyl group
Is C₁~ C₆Degree is preferred, and the carboxyl group is 1 to
Preferably about 3), or an aliphatic carboxylic acid (calcium
The portion other than the boxyl group (about 1 to 3) has 1 to 2 carbon atoms.
Containing about 0, preferably about 2 to 12 ether oxygens
Is an aliphatic hydrocarbon residue which may be
The alcohol moiety has about 1 to 8 carbon atoms, preferably 1 to 4 carbon atoms.
To the extent that the corresponding hydroxy substitution of the carboxylic acid is
Including intramolecular esters of conductors), for example, phenyl
Ethyl acetate, methyl benzoate, ethyl benzoate, benzoate
Phenyl acid, methyl toluate, ethyl toluate,
Methyl nisate, ethyl anisate, methyl methoxybenzoate
, Ethyl methoxybenzoate, methyl methacrylate,
Ethyl acrylate, dimethyl phthalate, diethyl phthalate
, Dipropyl phthalate, dibutyl phthalate, phthalic acid
Diisobutyl, dihexyl phthalate, γ-butyrolact
, Ethyl cellosolve, etc.
The class includes alkoxy groups (including aryloxy groups).
About 1 to 18 carbon atoms, especially about 1 to 4
Is preferable) and at least one silicon atom remaining
The valence of is an alkyl group, an aryl group or an aralkyl group
(These general descriptions are the same as those described above.)
Some, tetramethoxysilane, ethyltrimethoxy
Silane, n-propyltrimethoxysilane, isopropyl
Rutrimethoxysilane, t-butyltrimethoxysila
, Phenyltrimethoxysilane, cyclohexyltri
Methoxysilane, 1-methylcyclohexyltrimethoxy
Sisilane, 1,1,2,2-tetramethylpropyltri
Methoxysilane, diethyldimethoxysilane, di-n-
Propyldimethoxysilane, diisopropyldimethoxy
Silane, diphenyldimethoxysilane, t-butylmethyl
Rudimethoxysilane, t-butylethyldimethoxysila
T-butyl-n-propyldimethoxysilane, t-
Butylisopropyldimethoxysilane, cyclohexyl
Methyldimethoxysilane, dicyclohexyldimethoxy
Silane, 1-methylcyclohexylmethyldimethoxy
Orchid, 1,1,2,2-tetramethylpropylmethyldi
Methoxysilane, ethyltriethoxysilane, n-pro
Pill triethoxy silane, isopropyl triethoxy
Run, t-butyltriethoxysilane, phenyltrie
Toxysilane, cyclohexyltriethoxysilane, 1
-Methylcyclohexyltriethoxysilane, 1,1,
2,2-tetramethylpropyltriethoxysilane, di
Ethyldiethoxysilane, di-n-propyldiethoxy
Silane, diisopropyldiethoxysilane, diphenyl
Diethoxysilane, t-butylmethyldiethoxysila
, T-butylethyldiethoxysilane, t-butyl-
n-propyldiethoxysilane, cyclohexylmethyl
Diethoxysilane, cyclohexylethyldiethoxy
Orchid, 1-methylcyclohexylmethyldiethoxysila
1,1,2,2-tetramethylpropylmethyldiene
Toxisilane and the like can be mentioned.

Of these compounds, those preferably used are piperidines or alkoxysilanes, and particularly preferably alkoxysilanes. The amount of these compounds is not limited, but is usually used so that the molar ratio to aluminum in the organoaluminum compound used as a cocatalyst is 0 to 10, preferably 0 to 2. Further, a plurality of electron donating compounds can be selected and used within each of the above groups and / or between each group.

A solid catalyst component, an organoaluminum compound,
Each catalyst component of the electron-donating compound used as necessary and in the polymerization tank or outside the polymerization tank, in contact with each other in the presence or absence of the monomer to be polymerized, by this contact, the present invention, A stereoregular catalyst is formed. Each catalyst component may be independently supplied to the polymerization tank, or may be supplied after contacting any of the components.
In this case, the contact method is arbitrary. That is, each component may be contacted simultaneously, or arbitrary components may be sequentially contacted. The method for supplying each of these components to the polymerization tank is not particularly limited. Propane, butane, pentane, hexane, heptane, octane, nonane, decane,
It may be supplied by dissolving or suspending it in an inert hydrocarbon solvent such as toluene or xylene, or it may be supplied directly without substantially using these inert hydrocarbon solvents.

The polymerization of the α-olefin of the present invention is carried out using multi-stage stirring blades, and can be carried out, for example, using the apparatus shown in FIG. In FIG. 1, a polymerization tank 1 has a multi-stage stirring blade, for example, a paddle blade 3 (a plurality of blades, especially three blades) and a turbine blade 4 on a stirring shaft 2. Slurry polymerization or bulk polymerization of olefins is carried out, and evaporation of evaporating substances such as α-olefin monomers or hydrocarbon solvents which evaporate due to the heat of reaction is cooled by the reflux condenser 5, and the condensate is collected by the recovery liquid drum 6 and the recovery liquid It is preheated by a heater 8 via a pump 7 and is recirculated (recycled) to the polymerization tank 1. In the case of bulk polymerization, for example, a polymerization method using liquid propylene itself as a medium is used.

In the present invention, the polymerization temperature in the polymerization tank 1 is not particularly limited, but is usually 40 to 120 ° C., preferably 50 to 90 ° C. The pressure is not particularly limited, but is usually 1 to 100 atm, preferably 5 to 50 atm.
m. The polymerization is optionally carried out in the presence of hydrogen. There is no particular limitation on the amount of hydrogen supplied to the polymerization tank, and hydrogen necessary for obtaining a desired melt flow rate (hereinafter, referred to as MFR) can be supplied.

As described above, in the polymerization tank 1, all or part of the reaction heat generated by the slurry polymerization or the bulk polymerization of the α-olefin is subjected to the α-olefin or hydrocarbon solvent used for the polymerization. It has a heat removal facility for removing the (dispersion medium) by evaporation. As shown in FIG. 1, the polymerization tank (stirring tank) 1 is provided with a multi-stage stirring blade, for example, a paddle blade 3 and a turbine blade 4 on a stirring shaft 2 for stirring the inside of the polymerization tank. The stirring shaft 2 is located at the center of the polymerization tank 1 and is disposed in the vertical direction, and multi-stage (multi-stage) stirring blades are provided in the vertical direction.

The paddle blade 3 is arranged at the lower end of the multi-stage stirring blade provided on the stirring shaft 2 and has a shape in a radial direction from the stirring shaft 2 as shown in FIG.
a, which protrudes from the agitating shaft 2 to the tip of the paddle blade 3 to increase the receding angle with respect to the rotation direction of the shaft, so that the receding angle of the tip is in the range of 25 to 50 ° and rises by 10 to 20 ° Three paddle blades 3 having a shape having an angle (γ) and generally called three-way swept wings are preferably used. Also,
As the size of the paddle blade 3, the diameter of the paddle blade 3 (d
The ratio (di / D) between i) and the diameter (D) of the stirring tank is 0.5
0.6 and the width (b) of the paddle blade 3a.
Ratio (b1 / di) between 1) and the diameter (di) of paddle blade 3
Is desirably in the range of 0.1 to 0.2.

The turbine type blade 4 is provided above the paddle blade 3 in one or more stages.
As shown in FIG. 3, turbine blades 4b inclined at equal intervals in the circumferential direction are fixedly mounted on a disk-shaped support plate 4a protruding in a direction orthogonal to the stirring shaft 2. When the ratio (di / D) of the diameter (di) of the turbine blade to the diameter (D) of the polymerization tank 1 is in the range of 0.4 to 0.5, the width (b2) of the turbine blade and the turbine blade The ratio (b2 / di) to the diameter (di) is in the range of 0.15 to 0.25, and the turbine blade 4b
The ratio (I / di) of the width (I) of the blade to the diameter (di) of the blade is in the range of 0.2 to 0.3.
It is preferable that four to six blades are provided in a state where the turbine blades are inclined at an inclination angle (θ) of 30 to 60 ° so that the discharge flow generated from the turbine blades is directed downward.

The paddle blade 3 has a position where the ratio (C / D) of the distance (C) between the lower end of the blade and the bottom of the polymerization tank 1 and the diameter (D) of the polymerization tank 1 is 0.2 or less. Located in
The turbine type blade 4 is disposed at a position substantially evenly distributed over a distance (L) between the paddle blade 3 and the liquid level 5 of the polymerization tank 1.
That is, the vertical spacing between the stirring blades is set at a distance substantially corresponding to the length (h) obtained by dividing the distance (L) between the normal liquid level and the paddle blade 3 by the number of stages of the stirring blades. It is desirable. Further, 4 to 12 baffle plates 11 are arranged on the side wall surface of the polymerization tank 1 along the side wall surface from the lower part to the upper part at intervals in the circumferential direction.

In the present invention, slurry polymerization or bulk polymerization of α-olefins is carried out in a polymerization tank using the above-described multi-stage stirring blades, and α-olefins are evaporated by the heat of the reaction.
-Olefin monomer or hydrocarbon solvent (dispersion medium)
And the evaporating gas linear velocity (Ug) of the superficially-based evaporating substance in the polymerization tank 1 is in the range of 1.0 to 4.0 cm / sec, preferably 1.5 to 3.5 cm / sec, and The bubble content of the vaporized substance in the slurry in the polymerization tank [bubble volume / (bubble volume + slurry volume)] is 3
0% by volume or less, preferably in the range of 5 to 25% by volume. Further, the liquid level height (H) in the polymerization vessel is 0.8 to 1 based on the lower end of the straight body of the reaction vessel. And the solid particle concentration [upper concentration] in the slurry at 0.
The ratio of the stirring rotation speed to the minimum stirring rotation speed [particle concentration equilibrium stirring rotation speed (Neqg)] required to keep the ratio of the solid particle concentration [lower concentration] in the slurry at the position of 0.1 constant. It is characterized in that it is operated under the condition of the number of rotations of stirring which can be 0.8 or more, preferably in the range of 1 to 1.5.

In the present invention, the minimum stirring speed required for the ratio of the upper concentration to the lower concentration of the solid particles in the slurry to be constant is defined as a value obtained when the rotation speed of the stirring shaft 2 is gradually increased. The rotation speed when the ratio between the upper density and the lower density does not change even when the rotation speed is increased. In addition, the evaporative gas linear velocity (U
g) calculates the amount of heat removed by the condenser installed at the top of the polymerization tank 1, calculates the amount of evaporative gas from the amount of heat removed, the latent heat of evaporation of the evaporant, and the gas density. Is calculated from the cross-sectional area of When a gas containing a large amount of hydrogen and the like that is not condensed by the condenser is blown into the polymerization tank, the amount of the gas is corrected.

When the above-mentioned evaporating gas linear velocity based on the empty tower is lower than the lower limit (1.0 cm / sec), the polymerization amount of the α-olefin monomer per unit time decreases, and the same amount of α-olefin monomer polymerization In order to obtain the amount, it is necessary to use a large polymerization tank, which is economically disadvantageous. on the other hand,
The upper limit (4.0 cm / sec)
c) When the size is larger, particles jump out from the liquid surface more frequently, which causes a decrease in the performance of the reflux condenser for heat removal, and in order to prevent the particles from jumping out,
It is economically disadvantageous because the size of the empty tower portion of the polymerization tank needs to be increased.

If the bubble content of the evaporating substance in the slurry in the polymerization tank is larger than the upper limit (30% by volume), the catalyst particles are not retained in the bubble portion contained, so that the residence time of the catalyst is substantially reduced. This is not preferable because there is a problem of lowering the substantial efficiency of the catalyst. Further, when the ratio of the stirring rotation speed to the minimum stirring rotation speed required for the solid particle concentration in the slurry to be constant is equal to or less than the lower limit (0.8), the upper and lower portions of the slurry held in the polymerization tank are not mixed. A difference in the concentration of the solid particles occurs, and the concentration of the solid particles in the upper portion is reduced, so that the residence time of the catalyst is substantially reduced.

Furthermore, stirring per unit volume by stirring
Required power is 0.5-3.0 kw / m ^ThreeThe range of the slurry
Mixing performance is good and desirable in terms of catalyst efficiency.
Required power is 0.5kw / m^ThreeIf less than the slurry in the stirring tank
The catalyst efficiency is greatly reduced due to the lower mixing performance of
3.0 kw / m^ThreeExceeds the required power for stirring
Economically disadvantageous and increase in the bubble content
The catalyst efficiency is also lowered. The present invention as described above
Is used for α-olefin slurry polymerization or bulk polymerization.
All or part of the reaction heat generated in the reaction
Α-olefin or hydrocarbon solvent (dispersion
Α-olefin that removes heat by evaporation of evaporating substances such as
Gas-Liquid-Solid represented by continuous polymerization method of polymer
Selection of stirring blade and stirring rotation speed in three-phase aeration stirring tank
The setting method is provided.

In the above-described combination of multi-stage blades, as shown in FIG. 4, when the stirring rotation speed is low even in a non-aerated state in which substantially no gas is passed, a portion of the stirring tank holding the slurry has a slurry layer. In some cases, the concentration of the solid particles in the upper and lower slurries cannot be a uniform mixed state. That is, the upper portion of the slurry layer has a low solid particle concentration, and the lower portion has a high solid particle concentration. In this phenomenon, the difference between the concentration of the upper part and the concentration of the lower part is eliminated by sequentially increasing the rotational speed of the stirring, and the concentration of the solid particles in the upper and lower portions becomes almost uniform.

The minimum agitation speed required for the slurry layer to have a substantially uniform solid particle concentration is called the particle concentration equilibrium agitation speed (Nus). The relationship has been found by the present inventors to be expressed by the following equation. Nus = K / ν ^0.05 · [g · (ρs−ρl) / ρl]
The symbols used in ^{0.4 · dp 0.47 · Ws 0. 22} / di 0.8 above equation will be described. Nus: Particle concentration equilibrium stirring speed under gas non-aeration condition [sec ^-1 ] K: Constant determined by shape of stirring blade ν: Kinematic viscosity of liquid [m ² / sec] ρs: Density of solid [Kg / m ^3] Ρl: density of liquid [Kg / m ³ ] Ws: concentration by weight of solid particles [wt%] dp: particle diameter of solid particles [m] di: diameter of stirring blade [m]

In a gas-liquid-solid three-phase aeration tank in which a gas is passed, Nus obtained by the above equation must be corrected because it is affected by the gas flow. In this phenomenon, buoyancy acts on the particles by aerating the gas, but the agitating blade causes aeration due to aeration and the agitation load power decreases. It is considered that the influence of the lowering of the stirring power appears more remarkably than the applied buoyancy.

Nusg = Nus · [K ′ · (Ug / Ut) ^0.16 ] The symbols used in the above equation will be described. Nus: Particle concentration equilibrium stirring speed [sec ^-1 ] under gas ventilation conditions K ': Constant determined by the shape of the stirring blade disposed at the bottom Ug: Empty tower base gas linear velocity [m / sec] Ut: static sedimentation velocity of solid particles [m / sec]

In many experiments of the present inventors, the aforementioned K is 1
By using 3 to 17 and K 'of 45 to 50, it became possible to estimate the particle concentration equilibrium stirring rotation speed. FIG. 5 shows the relationship between the above equation and the actual measurement result. Similarly, in the above-described combination of multi-stage blades, a change in the gas content in the slurry in a state where the gas was ventilated was examined. As a result, as shown in FIG. , And furthermore, it was found that it was different depending on the stirring rotation speed.

When gas is passed, the density of the slurry decreases due to the inclusion of the gas in the slurry, and in particular, the phenomenon of including air bubbles behind the blade in the rotating direction of the blade, which is often seen in turbine blades (ie, the formation of cavities). The power required for stirring is reduced. The present inventors have obtained an equation for estimating the power required for stirring under gas aeration conditions using a number of experimental results.

Pgv = K · ρ _av · Ug ^(1-B) / [Fr
^1.2 · D ^0.5 ] ^(-B) The symbols used in the above equation will be described. Pgv: Power required for stirring under aeration per unit volume [W /
m ³ ] K: Constant depending on shape and combination of stirring blades ρ _av : Average density of slurry Ug: Gas flow linear velocity based on empty tower of polymerization tank [m / sec]
c] Fr: stirring fluid number Fr = n ² · di / g In the case of a multistage blade, the sum of the Fr numbers of the stirring blades is used. n: stirring rotation speed [sec ^-1 ] di: diameter of stirring blade [m] g: acceleration of gravity 9.81 [m / sec ² ] D: diameter of polymerization tank [m] B: constant K = 0.5 to 1.0 and B = 1.0 to 1 in the combination of the turbine type blade 2 stage + 3 paddle blades used.
5 can be used to estimate Pgv.

Next, the result of obtaining an equation for estimating the gas content of the slurry in a state where the gas is passed (that is, gas hold-up εg) will be described. As described above, it can be seen from FIG. 6 that the gas holdup is related to the ventilation gas linear velocity and the power required for stirring. Further, from the results of many experiments by the present inventors, it was found that when the solid particle concentration in the slurry was increased, the gas hold-up was reduced, and that the particle size of the solid particles in the slurry was slightly affected. Based on a model that considers energy dissipation in a turbulent state as a correlation equation for gas hold-up, the following estimation formula was obtained that considered the effects of slurry concentration and the size of solid particles.

Εg / (1−εg) = K · [(Pg / Q
_{g) / {ρ av · (} g · μ av / ρ av) 2/3} ] ^1/5 · [Q
g / (g · di ⁵ ) ^1/2 ] ^4/5 · [g · di ² · ρ _av /
σ] ^1/5 · ^{_{[(μ av / ρ av) 2}} / (g · di 3) ] ^2/45
・ [Ρ _av / (ρ _av −ρ _g )] ・ (ρ _g / ρ _av ) ^1/15・
^{_{(Μ av / μ l) -1/4}} · (1 + Ut / U turb) -1/10

The symbols used in the above equation will be described. K: coefficient εg: bubble content in slurry [gas / (gas + slurry)] [-] Pg: required power for stirring under aeration [W] Qg: gas aeration [m ³ / sec] ρ _av : average slurry Density [Kg / m ³ ] μ _av : average slurry viscosity [Kg / m / sec] μ _l : liquid viscosity [Kg / m / sec] ρ _g : gas density [Kg / m ³ ] σ: surface tension [N / m] di: diameter of stirring blade [m] g: acceleration of gravity 9.81 [m / sec ² ] Ut: stationary sedimentation velocity [m / sec] of solid particles _Uturb : turbulent characteristic velocity 1.4 · (Np ・ n ³・ di ⁵
/ V · dp) ^(1/3) [m / sec] Np: Power number n: Stirring speed [sec ^-1 ] V: Volume of slurry layer in polymerization tank [m ³ ] dp: Average particle size of solid particles Diameter [m] In the combination of two turbine blades and three paddle blades used by the present inventors, it is possible to estimate the bubble content using K = 0.06 to 0.10.

The empirical formulas for estimating the power required for agitation under uniform gas mixing, gas aeration, and bubble content have been described above, but the present invention is not limited to these formulas. As described above, in the method for producing an α-olefin polymer by slurry polymerization or bulk polymerization, all or a part of the reaction heat due to polymerization is converted to the evaporation material such as the α-olefin monomer or hydrocarbon solvent (dispersion medium). In order to increase the amount of solid particles in the slurry containing bubbles substantially and increase the efficiency of the catalyst in the reaction tank attached to the heat removal equipment that utilizes the latent heat of evaporation by evaporation, the uniform mixing performance of the slurry was improved. Further, it is important to reduce the content of bubbles in the slurry. By using each of the above-described estimation formulas shown by the present invention, the internal state of the reactor is predicted, and appropriate design becomes possible.

Hereinafter, the present invention will be described with reference to Examples and Comparative Examples, but the present invention is not limited thereto.

[0049]

EXAMPLES The following examples and comparative examples were carried out using the following reaction apparatus and measuring apparatus. A reflux condenser 5 for condensing and liquefying the gas evaporated in the polymerization tank 1 as shown in FIG. 1, a drum 6 holding the condensed liquid, a pump 7 for recirculating the recovered liquid to the polymerization tank 1 again, and An inner diameter of 750 mm, a height of 1370 mm, and a capacity of 0.66 m having a heater 8 for heating and evaporating the liquid as accessory equipment.
^The stirring shaft 2 is disposed at the center of the vertical polymerization tank ³ and has a distance of 80 mm from the bottom wall surface of the polymerization tank 1 to the lower end of the blade, where di = 436 mm and b1 = 65 mm. ,
Three paddle blades 3 having a receding angle of about 30 ° and an ascending angle of about 15 ° are arranged, and di is spaced above each by about 320 mm.
= 300 mm, b2 = 60 mm, I = 76 mm, and the paddle blade has an inclination angle of about 45 ° downward.
It was arranged in steps. The stirring shaft 2 is provided at 0 to 36
It is rotated by an inverter motor 10 whose rotation speed can be changed within a range of 0 r / m. In addition, a double-tube slurry cooler 9 for cooling and eliminating bubbles contained in the slurry by evaporating gas is provided in a line for extracting the reaction slurry from the bottom of the polymerization tank 1 to the downstream processing equipment. installed.

The measuring device and method will be described below. A torque meter A for measuring the power required for stirring and a photoelectric tachometer B for measuring the number of rotations are attached to the outer portion of the tank of the stirring shaft 2. An orifice type differential pressure flow meter C is disposed between the stirring tank and the reflux condenser 5 to measure the linear evaporation rate of the gas in the superficial tower inside the polymerization tank 1. As a means for measuring the solid particle concentration in the slurry inside the reactor, a sampling tube D and a valve are provided at a position inserted 50 mm and 750 mm above the lower end of the straight body of the reactor and 200 mm inside from the side wall of the stirring tank. The solid particle concentration was determined by sampling.

Further, a radiation type densitometer E is installed downstream of the double-tube slurry cooler 9 installed in the bottom extraction line of the polymerization tank, and the solid concentration in the slurry is obtained by measuring the slurry density. Was. The content (εg) of bubbles in the slurry inside the reactor was determined by measuring two radiation type densitometers E at approximately the same height as the above-mentioned sampling tube arrangement position and a double tube cooler at the bottom extraction line of the stirring tank. A radiation type densitometer E is disposed on the distillation side of, and by measuring the average density of the slurry containing bubbles, the bubble content is calculated by the following formula using the solid particle concentration in the slurry separately obtained. Calculated.

Ρ _slurry = 100 / ｛[solid] / ρ
_s + (100− [solid]) / ρ _l εεg = (ρ _slurry −ρ _av ) / (ρ _slurry −ρ _g ) × 10
0 The symbols used in the above equation will be described. ρ _slurry : average density of slurry (liquid and solid) not containing bubbles [kg / m ³ ] [solid]: concentration of solid particles in slurry not containing bubbles [wt%] ρ _s : density of solid [kg / m] ³ ] ρ _l : Density of liquid [kg / m ³ ] ρ _av : Average density including bubbles measured by radiation densitometer [kg / m ³ ] ρ _g : Gas density of evaporative gas [kg / m ³ ]

Example 1 In the polymerization tank shown in FIG.
44 m ³ (L / D = 1.16), polymerization temperature 70 ° C., pressure 32.5 kg / cm ² G, stirring rotation speed 250 r / m, gas evaporation linear velocity 3.0 cm / sec (evaporation amount 3.5 Ton)
/ H), a solid catalyst supply amount of 1.10 g / h, and a propylene supply amount of 110 Kg / h, bulk continuous polymerization of polypropylene was performed. In this operation, the power required for stirring was 0.48 kw (Pv = 1.5 kw / m ³ ), and the polypropylene particle concentration obtained by sampling the upper and lower parts of the reaction tank was almost uniform at 44% by weight at the upper part and 45% by weight at the lower part. Yes, the bubble content calculated from the radiation densitometer is 2
It was 7.0% by volume. The particles obtained by continuous polymerization had an average particle size of 600 μm, the catalyst efficiency was 45,100 g-polypropylene / g-catalyst, and the polypropylene was obtained at an average production rate of 50 kg / h. Under these operating conditions, the calculated particle concentration equilibrium stirring speed is 240 r / m.
Met.

(Embodiment 2) Evaporation linear velocity of gas was 1.5 cm
/ Sec (evaporation amount 1.8 Ton / h), except that bulk continuous polymerization of polypropylene was performed under the same conditions as in Example 1. In this operation, the power required for stirring is 0.58 k
w (Pv = 1.65 kw / m ³ ), and the polypropylene particle concentration obtained by sampling the upper and lower parts of the reaction tank is almost uniform at 45% by weight at the upper part and 47% by weight at the lower part. The bubble content was 20.0% by volume. The particles obtained by continuous polymerization have an average particle size of 6
10 μm, efficiency of the catalyst is 47,300 g-polypropylene / g-catalyst, and polypropylene is 52 Kg on average.
/ H production rate. The calculated particle concentration equilibrium stirring speed under these operating conditions was 216 r / m.

Example 3 A bulk continuous polymerization of polypropylene was carried out under the same conditions as in Example 1 except that a slightly smaller catalyst was used than the catalyst used in Example 1. In this operation, the power required for stirring is 0.48 kw (Pv = 1.5 k
w / m ³ ), and the polypropylene particle concentration by sampling at the top and bottom of the reaction tank was 45% by weight in the upper part and 4% in the lower part.
The content was uniform at 5% by weight, and the content of air bubbles calculated by a radiation densitometer was 26.0% by volume. The particles obtained by continuous polymerization have an average particle size of 400 μm and a catalyst efficiency of 4
4,900 g-polypropylene / g-catalyst, polypropylene being obtained at an average production rate of 50 kg / h. The calculated particle concentration equilibrium stirring rotation speed under these operating conditions was 207 r / m.

(Example 4) Bulk continuous polymerization of polypropylene was carried out under the same conditions as in Example 3 except that the stirring speed was changed to 200 r / m. In this operation, the power required for stirring was 0.26 kw (Pv = 0.78 kw / m ³ ), and the polypropylene particle concentration obtained by sampling the upper and lower parts of the reaction tank was 35% by weight at the upper part and 44% by weight at the lower part in a uniform mixing state. And the solids concentration at the top was slightly reduced. The bubble content calculated from the radiation densitometer is 23.5.
% By volume. The particles obtained by continuous polymerization had an average particle size of 390 μm, and the efficiency of the catalyst was 43,000 g-polypropylene / g-catalyst, which was almost the same as that of Example 1. The polypropylene in this polymerization was obtained at an average production rate of 48 kg / h. The calculated particle concentration equilibrium stirring speed under these operating conditions is 207 r /
m, and the operation stirring rotation speed was 0.96 with respect to the particle concentration equilibrium stirring rotation speed.

(Comparative Example 1) Bulk continuous polymerization of polypropylene was performed under the same conditions as in Example 1 except that the stirring rotation speed was changed to 190 r / m. In this operation, the power required for stirring was 0.23 kw (Pv = 0.53 kw / m ³ ), and the polypropylene particle concentration obtained by sampling the upper and lower parts of the reaction tank was 12% by weight at the upper part and 41% by weight at the lower part in a uniform mixing state. And the solids concentration at the top was reduced. The bubble content calculated by the radiation densitometer was 24.0% by volume. The particles obtained by continuous polymerization have an average particle size of 58.
0 μm, the catalyst efficiency was 40,000 g-polypropylene / g-catalyst.
% Decreased. The polypropylene in this polymerization averages 45
Obtained at a production rate of Kg / h. Under the operating conditions, the calculated particle concentration equilibrium stirring rotation speed was 240 r / m, and the operation stirring rotation speed was 0.79 with respect to the particle concentration equilibrium stirring rotation speed.

(Comparative Example 2) Bulk continuous polymerization of polypropylene was carried out under the same conditions as in Example 1 except that the number of revolutions for stirring was changed to 350 r / m. In this operation, the power required for stirring was 1.15 kW (Pv = 3.8 kw / m ³ ), which required 2.5 times the stirring power as compared with Example 1. The polypropylene particle concentration obtained by sampling the upper and lower portions of the reaction tank was 45% by weight at the upper portion and 45% by weight at the lower portion, which was in a substantially uniform mixed state. The bubble content calculated by the radiation densitometer was as high as 35.0% by volume. The particles obtained by continuous polymerization have an average particle size of 590 μm, and the efficiency of the catalyst is 43,000 g-polypropylene / g-catalyst,
Compared to Example 1, the efficiency of the catalyst is reduced by about 5%, but the power required for stirring is extremely high, which is industrially quite disadvantageous. The polypropylene in this polymerization averages 50
Obtained at a production rate of Kg / h. The calculated particle concentration equilibrium stirring rotation speed under these operating conditions was 240 r / m.

(Comparative Example 3) Bulk continuous polymerization of polypropylene was carried out under the same conditions as in Example 1 except that the stirring rotation speed was changed to 150 r / m. About 30 hours after the start of the operation, the tendency of the reactor withdrawal line to be blocked became remarkable, and it became impossible to control the liquid level in the reactor, leading to a continuous polymerization operation stop. The average particle size of the polypropylene particles obtained by this operation was almost normal at 580 μm, but the broad particle size distribution contained 2.5 to 7% by weight of giant particles of 2.0 mm or more. In the sampling during operation, 5
When the concentration was lower than 60% by weight, the uniformity of the particle concentration was extremely poor at 60% by weight. In this operation, the power required for stirring was 0.11 kW (Pv = 0.26 kw / m ³ ), and it is considered that giant particles were generated due to poor flow of the particles inside the reactor.

(Comparative Example 4) The gas evaporation linear velocity was 4.5 cm.
/ Sec (evaporation amount 5.3 Ton / h), except that bulk continuous polymerization of polypropylene was performed under the same conditions as in Example 1. In this operation, the power required for stirring is 0.42 k
w (Pv = 1.40 kW / m ³ ), and the polypropylene particle concentration obtained by sampling the upper and lower parts of the reaction tank was 20 wt% in the upper part and 44 wt% in the lower part. In addition, the content of air bubbles calculated by a radiation density meter was 31.2% by volume. The particles obtained by continuous polymerization have an average particle size of 580 μm and a catalyst efficiency of 3
9,500 g-polypropylene / g-catalyst, the efficiency of the catalyst was reduced by about 13% compared to Example 1. Polypropylene was obtained at an average production rate of 45 Kg / h. The calculated particle concentration equilibrium stirring rotation speed under these operating conditions was 257 r / m, and the operation stirring rotation speed was 0.97 with respect to the particle concentration equilibrium stirring rotation speed.

[0061]

According to the present invention, there is provided a polymerization method for evaporating an evaporation material such as an α-olefin monomer or a hydrocarbon-based solvent (dispersion medium) by slurry polymerization or bulk polymerization of α-olefin and removing heat of polymerization or heat of stirring by latent heat of evaporation. The efficiency of the catalyst in the polymerization reactor was increased by setting the stirring speed to maintain the balance between the content of bubbles in the slurry due to gas evaporation and the uniform mixing performance of the solid particles in the slurry, and the power required for stirring was reduced. .

[Brief description of the drawings]

FIG. 1 is a flowchart showing steps related to a manufacturing method of the present invention.

FIGS. 2A and 2B are a top view and a side view showing three paddle blades, respectively.

FIGS. 3A and 3B are a top view and a side view showing a turbine blade, respectively.

FIG. 4 is a graph showing an example of a measurement result of a relationship between a stirring rotation speed and a particle concentration in a reaction tank.

FIG. 5 is a graph showing a relationship between a measured value of a particle concentration equilibrium stirring speed and an estimated calculated value.

FIG. 6 is a graph showing an example of a measurement result of a relationship between a gas ventilation linear velocity and a bubble content.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Polymerization tank 2 Stirring shaft 3 Paddle blade 4 Turbine blade 5 Reflux condenser 6 Recovered liquid drum 7 Recovered liquid pump 8 Heater 9 Slurry cooler 10 Electric motor 11 Baffle plate A Torque meter B Photoelectric tachometer C Orifice type differential pressure flow meter D Sampling tube E Radiation density meter

 ──────────────────────────────────────────────────続 き Continued on the front page F-term (reference) 4J011 AA01 AB03 AB08 AB09 DB16 DB19 DB27 FA01 FB07 FB11 FB19 PA23 4J028 AA01A AB01A AC06A BA00A BA01B BB00A BB01B BC15B BC19B BC25B BC27B CA15A CA16A CB35EB02 EB35 EB35 EB35 EB35 EB35 CB35ACB

Claims (3)

[Claims] 1. A polymerization tank equipped with a multi-stage stirring blade,
In the method for producing an α-olefin polymer, in which an α-olefin is subjected to slurry polymerization or bulk polymerization in the presence of a stereoregular catalyst, and the generated heat of heat is removed using latent heat due to evaporation of an evaporating substance, A superficial evaporating linear velocity (Ug) of 1.0 to 4.0 cm / s in a stirred tank of the substance
ec, the bubble content of the evaporated substance in the slurry in the polymerization vessel [volume of bubbles / (volume of bubbles + volume of slurry)] is 30% by volume or less, and the liquid in the polymerization vessel is not more than 30% by volume. With respect to the surface height (H), the solid particle concentration in the slurry at a position of 0.8 to 1.0 and the solid particle concentration in the slurry at a position of 0 to 0.1 with respect to the lower end of the straight body of the polymerization tank. The minimum agitation rotation speed (Nus
A method for producing an α-olefin polymer, characterized in that the mixture is operated at a stirring speed of 0.8 or more with respect to g). 2. The solid particle concentration in the slurry at a position of 0.8 to 1.0 with respect to the liquid level height (H) in the polymerization tank with respect to the lower end of the straight body of the polymerization tank as 0 to 0.1. The method for producing an α-olefin polymer according to claim 1, wherein the α-olefin polymer is operated at a stirring rotation speed equal to or higher than a minimum stirring rotation speed (Nusg) required to make the ratio of the concentration of gas particles in the slurry at the position (1) constant. 3. The stirring blade comprises a paddle blade and a turbine blade protruding from a stirring shaft, and the paddle blade is disposed at a lower end of the stirring shaft, and has a shape extending from the stirring shaft to a tip end of the blade. The paddle blade has an increased swept angle with respect to the rotation direction of the shaft, and the swept angle at the tip end is in the range of 25 to 50 °, and includes three paddle blades having an ascending angle (γ) of 10 to 20 °. Ratio (di / d) of the diameter (di) of the stirring vessel to the diameter (D) of the stirring tank.
D) is in the range of 0.5 to 0.6, and the ratio (b1 / b1) between the width (b1) of the paddle blade and the diameter (di) of the paddle blade.
di) is in the range of 0.1 to 0.2, and the turbine blade is provided above the paddle blade,
Its size is such that the ratio (di / D) of the diameter (di) of the turbine blade to the diameter (D) of the stirring tank is in the range of 0.4 to 0.5, and the width (b2) of the turbine blade. The ratio (b2 / di) to the diameter (di) of the turbine blade is in the range of 0.15 to 0.25, and the length (I) of the blade of the turbine blade and the diameter (di) of the turbine blade are Ratio (I / di) is 0.2 to
0.3, and the blade of the turbine type blade is 30
The paddle blades are provided in a number of 4 to 6 with an inclination angle (θ) of ６０60 °. The distance (C) between the lower end of the blades and the bottom of the stirring tank and the diameter (D) of the stirring tank ) Ratio (C /
2. The method according to claim 1, wherein D) is disposed at a position where 0.2 or less.
Or the method for producing an α-olefin polymer according to item 2.