JP2001247606A - Method for producing alpha-olefin polymer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing an α-olefin polymer capable of achieving a decrease in slurry pump performance degradation, inhibiting cavitation in the pump, preventing reduction in pump transportation capacity, or the like. SOLUTION: The method for producing an α-olefin polymer, wherein a polymerization tank is used for the slurry polymerization on bulk polymerization of an α-olefin in the presence of a stereospecific catalyst and wherein the heat of polymerization is removed by the user of latent heat of vaporization resulting from the evaporation of an evaporating substance, is characterized, during the process of drawing slurry out of the polymerization tank by the use of a slurry pump, in that the vaporization linear velocity (UG) of the evaporation substance in the tank by the superficial velocity base is 1.0-4.0 cm/sec, that the content of air cells in the evaporating substance at the suction port of the pump is not more than 25 vol.%, and that the pump is operated at an agitating revolution number not less than 0.80 times the minimum agitating revolution number that keeps constant the ratio of the upper level concentration of solid particles to the lower level concentration of the same in the slurry in the tank.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention utilizes the latent heat of vaporization of an .alpha.-olefin monomer or a hydrocarbon solvent (dispersion medium) for all or part of the reaction heat generated in slurry polymerization or bulk polymerization of .alpha.-olefin. And removing or circulating a polymerization slurry from the polymerization tank while removing heat by using a slurry pump.

[0002]

2. Description of the Related Art All or a part of the reaction heat generated during slurry polymerization or bulk polymerization of an α-olefin is converted to α-olefin.
-A method utilizing the latent heat of evaporation by evaporation of an olefin monomer or a hydrocarbon-based solvent (dispersion medium) is disclosed in
These methods are generally well known as disclosed in JP-A No. 1-7084, JP-A-62-107-17705 and the like.

[0003] In order to improve the quality and productivity of α-olefin polymer products, a multi-stage polymerization method in which two or more reaction vessels are connected in series is disclosed in, for example, Japanese Patent Publication No.
43409 and the like.

Further, in a method for producing a propylene-based block copolymer, a method for suppressing a short path of polypropylene particles in a first reaction tank for the purpose of improving impact resistance is disclosed in, for example, JP-A-51-135879.
Japanese Patent Application Laid-Open No. 55-116716 discloses a method for concentrating and classifying polypropylene particles in a first reaction tank.
No. 06533, a method for countercurrent washing of a polymerization slurry extracted from a first reaction tank,
There is a method using a classification system using a cyclone in No. 004, etc. In many cases, a slurry pump is used for the purpose of extracting the slurry from the polymerization tank or supplying the slurry to the classification equipment in the above-described method.

Further, in the above-mentioned method for producing α-olefin polymer by α-olefin slurry polymerization or bulk polymerization using a slurry pump for extracting the slurry from the polymerization tank and supplying the slurry to the classification equipment, Many methods utilizing the latent heat of vaporization by evaporation of α-olefin monomers or hydrocarbon solvents (dispersion media) are used in combination to remove the heat of reaction due to the polymerization of olefins.

[0006] The stirring tank of the above-mentioned method utilizing the evaporation of an α-olefin monomer or a hydrocarbon solvent (dispersion medium) is generally called a gas-liquid-solid three-phase gas-flow stirring tank. Frequently used stirring blades are a plurality of stages of turbine type stirring blades or a combination of a plurality of stages of turbine type stirring blades and three paddle blades (three-way swept blades).

The gas generated by the evaporation of the α-olefin monomer or the hydrocarbon-based solvent (dispersion medium) passes through the slurry portion of the stirring tank and rises to a gaseous phase above the stirring tank that does not substantially contain slurry. To go.

When the evaporation of the monomer or the dispersion medium increases,
Under the influence of the rising gas, the force exerted on the slurry by the stirring blade (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 below the slurry layer, and the slurry having a high particle concentration is supplied to the slurry pump. Adhesion and clogging of the stagnated polymer particles due to reaction growth occur, causing a decrease in the performance of the slurry pump.

The above phenomenon is caused by the liquid level height (H) in the polymerization tank, and the lower end of the straight body (lower Tangential Lin).
e) and the solid particle concentration [upper concentration] in the slurry at the position of 0.9 to 1.0 × H and 0 to 0.1 × H
Of solid particles in slurry at lower position [lower concentration]
Is remarkable under the condition of the stirring rotation speed at which the ratio of the stirring rotation speed to the minimum stirring rotation speed [particle concentration equilibrium stirring rotation speed (Nus or Nusg)] required to keep the ratio constant is 0.8 or less.

Further, when the stirring rotation speed is low or the evaporation amount of the α-olefin monomer or the hydrocarbon solvent (dispersion medium) increases, the particle suspension limit stirring rotation speed (Njs or Njs) is increased.
g) The number of rotations under stirring becomes below, hinders the suspension of particles generated in bulk polymerization, and becomes a state of stagnation at a high concentration at the bottom of the polymerization tank. It becomes a factor that hinders stable operation of the slurry pump such as blockage.

[0011] The phenomenon of lowering the uniform mixing performance of the slurry and obstructing the suspension of the solid particles is caused by an increase in the linear velocity (Ug) of the gas passing through the air column based on the amount of gas passing through the slurry layer divided by the sectional area of the stirring tank. And the weight-based solid particle concentration in the slurry (Ws), the average particle size of the solid particles (dp), the density of the solid and the liquid 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).

Although the above-mentioned phenomenon tends to be eliminated by increasing the number of rotations of stirring, the power required for stirring increases and the content of bubbles in the slurry in the polymerization tank increases, which is industrially preferable. It can not be said.

When the content of bubbles in the slurry in the polymerization tank increases, the bubbles flow into the slurry pump connected to the slurry extraction line of the polymerization tank, and the bubble content of the slurry pump suction increases, and This causes a remarkable performance decrease phenomenon, which is a factor that hinders stable operation such as a decrease in the transport capacity of the slurry pump and settling, adhesion, and blockage of solid particles in the slurry in the transport pipe.

Further, when the content of bubbles in the slurry at the time of suction of the slurry pump is increased, the cavitation phenomenon of the slurry pump is caused, so that not only the slurry cannot be transported but also the failure of the slurry pump may be caused.

The bubble content at the suction of the slurry pump has a close correlation with the increase and decrease of the bubble content in the polymerization tank. It tends to increase due to an increase in the amount of gas generated by evaporation of the monomer or hydrocarbon-based solvent (dispersion medium) per unit area of the polymerization tank and an increase in the amount of slurry withdrawn from the polymerization tank to the slurry pump.

In general, a centrifugal pump is used to transport the liquid. The centrifugal pump is roughly classified into a volute pump and a turbine pump according to the structure of the impeller.

A volute pump having a structure in which an impeller accommodated in a casing is built in between two disks is called a closed type, and a type in which the impeller is exposed to the pump suction side is opened. Generally called a type.

[0018] Generally, a turbine pump has a structure in which deterioration of performance and cavitation hardly occur due to the incorporation of air bubbles sucked into the pump. However, due to the structure of the impeller, the transport of slurry containing solid particles is difficult. It is easy to cause adhesion and blockage, and is not often used.

In general, a closed-type volute pump has a structure that is less susceptible to entrainment of air bubbles than an open-type volute pump, and because of the structure of an impeller, solid particles cannot be transported. It is easy to cause adhesion and blockage, and is not often used.

In the case of slurry polymerization or bulk polymerization of α-olefin, when the above-described adhesion phenomenon occurs, the solid particles themselves react and grow, forming a huge lump inside the casing of the pump, and only the deterioration of the pump performance and the cavitation phenomenon Instead, closed-type volute pumps and turbine pumps are not used because they cause pump failure, and open-type volute pumps are generally used (for example,
Sanwa Hydrotech ID pump etc.).

When a general open-type volute pump is used as the slurry pump, the performance of the slurry pump deteriorates remarkably due to an increase in the content of air bubbles in the suction of the slurry pump. The nature becomes high.

When the slurry is transported using a slurry pump or the like, if the slurry flow rate in the transport pipe is low, solid particles will deposit on the bottom of the pipe, and as described above, the solid particles will be transferred from the polymerization tank to the slurry pump. An increase in the amount of slurry withdrawn causes a phenomenon in which the bubble content in the suction of the slurry pump increases.

If the above-mentioned phenomenon of the performance deterioration of the slurry pump, and hence the cavitation phenomenon of the slurry pump occurs, not only will the productivity of slurry polymerization or bulk polymerization of α-olefins be significantly lowered, but also the stable operation will be impaired. It is hard to say that it is difficult to adopt it industrially anymore.

[0024]

SUMMARY OF THE INVENTION An object of the present invention is to provide α-
Includes heat removal equipment that removes all or part of the reaction heat generated in the olefin slurry polymerization or bulk polymerization by evaporating the α-olefin or hydrocarbon solvent (dispersion medium) used in the polymerization. A polymerization tank and a method for producing an α-olefin using a slurry pump for extracting or circulating a polymer slurry produced by the polymerization, wherein sedimentation and separation of solid particles in the slurry of the polymerization tank are prevented to improve the uniform mixing performance of the slurry. And a stirrer rotation that balances the opposite phenomena in the stirrer speed setting plane, which lowers the content of bubbles generated in the slurry by the evaporation of the α-olefin or hydrocarbon solvent (dispersion medium) in the suction of the slurry pump. By setting the number, reduce the performance degradation phenomenon of the slurry pump and prevent cavitation of the pump More is to provide a manufacturing method that does not cause phenomena of transport capacity decrease transportation difficulties such slurry pumps α- olefin polymer.

[0025]

Means for Solving the Problems The present invention has been made as a result of intensive studies in order to achieve the above object, and uses an polymerization tank to convert an α-olefin into the presence of a stereoregular catalyst. In a method for producing an α-olefin polymer in which slurry polymerization or bulk polymerization is performed and heat of polymerization generated in the polymerization is removed by using latent heat due to evaporation of an evaporating substance, the slurry in the polymerization tank is formed using a slurry pump. While extracting, the evaporation linear velocity (Ug) of the evaporating substance based on the superficial tower in the polymerization tank is in the range of 1.0 to 4.0 cm / sec, and the bubble content of the evaporating substance in the slurry at the suction part of the slurry pump [ (Volume of bubble / (volume of bubble + volume of slurry) × 100] is 25% by volume or less, and the liquid level height (H) in the polymerization vessel is 0.9 H based on the lower end of the straight body of the polymerization vessel. ~ 1.0H Of the solid particles in the slurry [upper concentration] and the solid particles concentration in the slurry at the position of 0 to 0.1H [lower concentration] with respect to the minimum stirring rotation required for the ratio to be constant. Is 0.8
An object of the present invention is to provide a method for producing an α-olefin polymer, wherein the method is operated at a stirring rotation speed of 0 or more.

[0026]

BEST MODE FOR CARRYING OUT THE INVENTION According to the method for producing an α-olefin polymer of the present invention, α-olefin is subjected to slurry polymerization or bulk polymerization in one or more polymerization tanks in the presence of a stereoregular catalyst. In a method for producing an α-olefin polymer in which heat of polymerization generated by polymerization is removed by utilizing latent heat due to evaporation of an evaporating substance, polymerization of the evaporating substance is performed while extracting a slurry in the polymerization tank using a slurry pump. Evaporation linear velocity (Ug) based on an empty tower in the tank is 1.0 to 4.0 cm
/ Sec, the bubble content of the vaporized substance in the slurry at the suction part of the slurry pump [volume of bubble / (volume of bubble + volume of slurry) × 100] is 25% by volume or less, and the liquid in the polymerization tank is not more than 25% by volume. With respect to the surface height (H), the solid particle concentration [upper concentration] in the slurry at a position of 0.9H to 1.0H with respect to the lower end of the straight body portion of the polymerization tank and 0 to 0.1
It is operated in a state where the ratio of the stirring rotation speed to the minimum stirring rotation speed required for the ratio of the solid particle concentration [lower concentration] in the slurry at the position H to be constant is 0.80 or more. You.

Further, preferred stirring tanks and stirring blades used for the polymerization of the α-olefin of the present invention are as shown in FIG.
A stirring shaft 2 rotatable by a drive source (motor 12) from the outside of the tank is provided at the center of the vertical cylindrical stirring tank 1, and the bottom of the stirring shaft 2 extends from the bottom wall of the stirring tank to the lower end of the stirring blade. And a paddle blade 3 disposed at a position where the ratio (C / D) of the distance (C) to the diameter (D) of the stirring tank becomes 0.2 or less, the shape of which is shown in FIG. In addition, the angle from the stirring shaft center to the tip of the blade has a receding angle (γ) increasing in the range of 25 to 50 ° with respect to the rotation direction of the shaft, and a rising angle (δ) of 10 to 20 °. The ratio (d1 / D) of the diameter (d1) to the diameter (D) of the stirring tank is in the range of 0.5 to 0.6, and the ratio of the blade width (b1) to the blade diameter (d1). (B1 / d1) is in the range of 0.1 to 0.2.

One or two or more stages of turbine type blades 4 are disposed above the three paddle blades 3 at substantially equal positions between the paddle blades and the liquid level of the stirring tank. 4
Is the diameter (d) of the turbine blade as shown in FIG.
The ratio (d2 / D) of 2) to the diameter (D) of the stirring tank is 0.4
In the range of 0.5 to 0.5, the blade width of the turbine type blade (b2)
(B2 / d2) of the diameter of the turbine blade (d2)
Is in the range of 0.15 to 0.25, and the blade length (l)
(L / d2) between the diameter and the diameter (d2) of the turbine type blade is in the range of 0.2 to 0.3, and 4 to 6 blades having an inclination angle (θ) of 30 to 60 ° are further provided. Are provided.

Further, a stirring tank is preferably used in which 4 to 12 baffle plates 5 are arranged at intervals from the lower part to the upper part of the stirring tank side wall surface along the side wall surface.

In the present invention, the α-olefin used as a raw material has 2 to 8 carbon atoms, for example, ethylene, propylene, 1-butene, 1-pentene, 1-pentene.
Hexene, 1-octene and the like can be mentioned.

In the polymerization of the α-olefin, a stereoregular catalyst or various components constituting the same, for example, a solid catalyst component, a cocatalyst, an electron donating compound if necessary, or a contact product thereof is placed in a polymerization tank. , And 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, “consisting of” includes those containing various suitable components in addition to the above main components.

The stereoregular catalyst used in the present invention has essentially no different solid catalyst components from conventional stereoregular catalysts of this kind. Stereoregular catalysts comprising a solid catalyst component, an organic Al compound and, if necessary, an electron-donating compound are known (for example, JP-A-56-811 and JP-A-58-830).
06, JP-A-4-218507, JP-A-6-253
No. 38, JP-A-57-63311, JP-A-61-21
No. 3208, Japanese Patent Application Laid-Open No. 62-187706, Japanese Patent Application Laid-Open
331233, JP-A-5-331234, JP-A-6
3-289004, JP-A-1-319508, JP-A-52-98706, JP-A-1-54007, and JP-A-3-72503).

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 chloride, magnesium bromide, magnesium iodide,
Magnesium halides such as magnesium fluoride;
Alkoxy magnesium halides, such as methoxy magnesium chloride, ethoxy magnesium chloride, isopropoxy magnesium chloride, butoxy magnesium chloride, hexoxy magnesium chloride, octoxy magnesium chloride; alloxy magnesium halides, such as phenoxy magnesium chloride, methylphenoxy magnesium chloride; methoxy magnesium Alkoxymagnesiums such as, ethoxymagnesium, isopropoxymagnesium, n-butoxymagnesium, n-octoxymagnesium, 2-ethylhexoxymagnesium;
Allyloxymagnesium such as phenoxymagnesium and methylphenoxymagnesium; and magnesium carboxylate such as magnesium laurate and magnesium stearate. Incidentally, these magnesium compounds may be used alone,
Mixtures may be used.

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 0
≤g≤4) tetravalent titanium compound
Object, specifically, TiCl_Four, TiBr_Four, TiI_FourSuch
Of titanium tetrahalide; Ti (OCH_Three) Cl_Three, T
i (OC_TwoH_Five) Cl_Three, Ti (On-C_FourH₉) Cl_Three,
Ti (OiC_FourH₉) Cl_Three, Ti (OCH_Three) B
r_Three, Ti (OC_TwoH_Five) Br_Three, Ti (On-C_FourH₉)
Br_Three, Ti (OiC_FourH₉) Br_ThreeSuch as trihalogen
Alkoxy titanium oxide, Ti (OCH_Three)_TwoCl_Two, Ti
(OC_TwoH_Five)_TwoCl_Two, Ti (On-C_FourH₉)_TwoCl_Two,
Ti (OiC_FourH₉)_TwoCl_Two, Ti (OCH _Three)_TwoBr
_Two, Ti (OC_TwoH_Five)_TwoBr_Two, Ti (On-C_FourH₉)_Two
Br_Two, Ti (OiC_FourH₉)_TwoBr_TwoDihalogen
Alkoxy titanium oxide, Ti (OCH_Three)_ThreeCl, Ti
(OC_TwoH_Five)_ThreeCl, Ti (On-C_FourH₉)_ThreeCl, T
i (OiC_FourH₉)_ThreeCl, Ti (OCH_Three)_ThreeBr,
Ti (OC_TwoH_Five)_ThreeBr, Ti (On-C_FourH₉)_ThreeB
r, Ti (OiC_FourH₉)_ThreeMonohalogen such as Br
Alkoxytitanium chloride, Ti (OCH_Three)_Four, Ti (OC_Two
H_Five)_Four, Ti (On-C_FourH₉)_Four, Ti (OiC_Four
H₉)_FourSuch as tetraalkoxy titanium; or these
Or a mixture of these with an aluminum compound,
Iodine compounds, sulfur compounds, other metal compounds, halogenated
Halogen is mixed with hydrogen, halogen, etc.
General formula Ti (OR)_gX_4-g(R is a hydrocarbon group, X is
Halogen and g represent a number satisfying 0 ≦ g ≦ 4)
For tetravalent titanium compounds, hydrogen halides, halogens, etc.
Therefore it is common to introduce.

As the electron donating compound in the solid catalyst component, any of the compounds generally used for producing this kind of solid catalyst component can be used. 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 the trialkylaluminum are substituted with a halogen, for example, chlorine, bromine or the like, for example, diethylaluminum chloride, ethylaluminum sesquioxide Chloride, (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 Dolides, (d) alkoxide-containing organoaluminum compounds, specifically those in which one or two of the above-mentioned trialkylaluminum alkyl groups are alkoxy groups (including aryloxy groups), especially those having about 1 to 8 carbon atoms Such as dimethylaluminum methoxide, diethylaluminum methoxide, diethylaluminum ethoxide, diethylaluminum phenoxide, (e) aluminoxane (also referred to as alumoxane), specifically, an alkyl group having 1 to 12 carbon atoms. Certain alkylaluminoxanes, for example,
Methylaluminoxane, ethylaluminoxane, isobutylaluminoxane and the like can be mentioned. Also,
These can be used in plural within each group and / or between each group.

The amount of the organoaluminum compound used is not particularly limited, but usually the molar ratio of aluminum in the organoaluminum compound to titanium in the solid catalyst component is 0.1 to 10,000, preferably 10 to 10,000. 500
0, more preferably 50 to 2,000.

As the electron donating compound used as required, 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, ethers, ketones, esters and alkoxysilanes can be generally mentioned.

(A) ethers having a total of about 2 to 18 carbon atoms, preferably about 4 to 12 carbon atoms, in the hydrocarbon residue bonded to ether oxygen, and having ether oxygen therein; For example, diethyl ether, dipropyl ether, diethylene glycol dimethyl ether, propylene glycol dimethyl ether, ethylene oxide, tetrahydrofuran, 2,2,5,5-tetramethyltetrahydrofuran, dioxane and the like,
(B) As the ketones, those having a total of about 2 to 18, preferably about 4 to 12 carbon atoms in the hydrocarbon residue bonded to the ketone carbonyl group, for example, acetone, diethyl ketone, methyl ethyl ketone, acetophenone, etc.
(C) As the esters, the carboxylic acid moiety is an aryl or aralkyl carboxylic acid (the aryl group or the aryl moiety is phenyl or lower (about C ₁ -C ₄ ) alkyl and / or lower (about C ₁ -C ₄ ) alkoxy Substituted phenyl is preferred, and the alkyl portion of the aralkyl group is
C ₁ -C about ₆ are preferred, a carboxyl group is about 1 to 3 are preferred), or aliphatic carboxylic acids (carboxyl groups (about 1-3) than the portion of about 1 to 20 carbon atoms, preferably 2 １２12, which is an aliphatic hydrocarbon residue which may contain about 1 to about 12 ether oxygens, and has an alcohol moiety of about 1 to 8 carbon atoms, preferably about 1 to 4 carbon atoms (corresponding to the above carboxylic acid). Including intramolecular esters of hydroxy-substituted derivatives), for example, ethyl phenylacetate, methyl benzoate, ethyl benzoate, phenyl benzoate, methyl toluate, ethyl toluate, methyl anisate, ethyl anisate, methyl methoxybenzoate ,
Ethyl methoxybenzoate, methyl methacrylate, ethyl methacrylate, dimethyl phthalate, diethyl phthalate,
Dipropyl phthalate, dibutyl phthalate, diisobutyl phthalate, dihexyl phthalate, γ-butyrolactone,
Ethyl cellosolve and the like (d) alkoxysilanes include at least one alkoxy group (including an aryloxy group, preferably having about 1 to 18 carbon atoms, more preferably about 1 to 4 carbon atoms), and a silicon atom Are the alkyl, aryl or aralkyl groups (these general descriptions are the same as described above), tetramethoxysilane, ethyltrimethoxysilane, n-propyltrimethoxysilane, isopropyl Trimethoxysilane, t-butyltrimethoxysilane, phenyltrimethoxysilane, cyclohexyltrimethoxysilane, 1-methylcyclohexyltrimethoxysilane, 1,1,2,2-tetramethylpropyltrimethoxysilane, diethyldimethoxysilane, di- n-propyldimethoxysila , Diisopropyl dimethoxysilane, diphenyl dimethoxysilane, t- butyl methyl dimethoxy silane, t- butyl ethyl dimethoxysilane,
t-butyl-n-propyldimethoxysilane, t-butylisopropyldimethoxysilane, cyclohexylmethyldimethoxysilane, dicyclohexyldimethoxysilane, 1-methylcyclohexylmethyldimethoxysilane, 1,1,2,2-tetramethylpropylmethyldimethoxysilane, ethyl Triethoxysilane, n-propyltriethoxysilane, isopropyltriethoxysilane, t-butyltriethoxysilane, phenyltriethoxysilane, cyclohexyltriethoxysilane, 1-
Methylcyclohexyltriethoxysilane, 1,1,
2,2-tetramethylpropyltriethoxysilane, diethyldiethoxysilane, di-n-propyldiethoxysilane, diisopropyldiethoxysilane, diphenyldiethoxysilane, t-butylmethyldiethoxysilane, t-butylethyldiethoxysilane , T-butyl-
Examples thereof include n-propyldiethoxysilane, cyclohexylmethyldiethoxysilane, cyclohexylethyldiethoxysilane, 1-methylcyclohexylmethyldiethoxysilane, 1,1,2,2-tetramethylpropylmethyldiethoxysilane, and the like.

Of these compounds, those preferably used are piperidines or alkoxysilanes, particularly preferably alkoxysilanes.

The amount of these compounds used is not limited,
Usually, it is 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 of the catalyst components may be independently supplied to the polymerization tank, or may be supplied after contacting any of the respective 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. It may be supplied by being dissolved or suspended in an inert hydrocarbon solvent such as propane, butane, pentane, hexane, heptane, octane, nonane, decane, toluene, xylene, or may be substantially supplied with these inert hydrocarbon solvents. It can also be supplied directly without the use of.

Hereinafter, the present invention will be described in more detail with reference to FIG.

In FIG. 15, a polymerization tank (stirring tank) 1 has a multi-stage stirring blade comprising a three-stage paddle blade 3 and a two-stage turbine blade 4 on a stirring shaft 2, and the presence of a stereoregular catalyst. The vapor of the α-olefin monomer or the hydrocarbon solvent, which is used for slurry polymerization or bulk polymerization of α-olefin and is evaporated by reaction heat, is cooled by the reflux condenser 7, and the condensate is collected by the recovery liquid drum 8 and the recovery liquid drum 8. It is preheated by the heater 10 via the liquid pump 9 and is recirculated (recycled) to the stirring tank 1.

Most of the α-olefin polymer produced in the polymerization tank is circulated in a slurry state by a slurry pump 11, and a part of the α-olefin polymer is withdrawn to the next step, and after being processed, is obtained as an α-olefin polymer product. Can be
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 is not particularly limited, but is usually 40 to 120 ° C., preferably 50 to 120 ° C.
Performed at ~ 90 ° C. The pressure is not particularly limited, but is usually 1 to 100 atm, preferably 5 to 50 atm. 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 a 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. Heat removal equipment for removing by evaporation of (dispersion medium), and α-
It has a slurry pump 11 for circulating the olefin polymer slurry and extracting a part thereof.

As shown in FIG. 1, the polymerization tank (stirring tank) 1 is provided with multi-stage stirring blades for stirring the inside of the polymerization tank 1, for example, three paddle blades 3 and turbine type blades 4. . The stirring shaft 2 is located at the center of the stirring tank 1 and is arranged vertically in the tank, and a multi-stage (multi-stage) stirring blade is provided in the vertical direction.

The three paddle blades 3 are arranged at the bottom of the multi-stage stirring blades provided on the stirring shaft 2 and have a shape from the stirring shaft center to the blade tip as shown in FIG. Is a shape having a receding angle (γ) that gradually increases in the range of 25 to 50 ° with respect to the rotation direction of the shaft and retreats backward, and a rising angle (δ) of 10 to 20 °. Three paddle blades 3 called "retreat wings" are preferably used. The size of the three paddle blades 3 is such that the ratio (d1 / D) of the diameter (d1) of the blades to the diameter (D) of the stirring tank is in the range of 0.5 to 0.6, and The ratio (b1 / d1) of the blade width (b1) to the blade diameter (d1) is preferably in the range of 0.1 to 0.2.

The turbine type blades 4 are provided above the three paddle blades 3 in one or two or more stages. The size of the turbine type blades is as shown in FIG. When the ratio (d2 / D) of the diameter (d2) of the blade to the diameter (D) of the stirring tank is in the range of 0.4 to 0.5, the blade plate width (b2) of the turbine blade and the diameter of the turbine blade (D2)
And the ratio (b2 / d2) is in the range of 0.15 to 0.25,
And the blade length (l) and the diameter of the turbine blade (d2)
(L / d2) is in the range of 0.2 to 0.3, and the rotation of the stirring shaft 2 causes the discharge flow generated from the turbine blade 4 to fall in the downward direction by 30 to 60 °. It is desirable that four to six blades having an inclination angle (θ) be provided.

The three paddle blades 3 are positioned such that the ratio (C / D) of 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 is 0.2 or less. Located in
The turbine type blades 4 are disposed at positions substantially evenly distributed over the distance (L) between the three paddle blades 3 and the position of the normal liquid level 6 of the stirring tank.

That is, the vertical interval between the stirring blades is the length (h) obtained by dividing the distance (L) between the normal liquid level 6 and the three paddle blades 3 by the number of stages of the stirring blades arranged + 1. It is desirable to arrange them at substantially equivalent intervals.

Further, from the lower part to the upper part, 4 to 12 baffle plates 5 are arranged at intervals on the side wall surface of the stirring tank along the side wall surface. The width (b) of the arranged baffle plate is b / D = 0.05 to 0.12 with respect to the diameter (D) of the stirring tank.
In the range, the length of the baffle plate in the up-down direction is generally a length that covers from the lower end (lower Tangential Line) of the straight body portion of the stirring tank to the liquid level position,
The lower end of the baffle may be above the lower end of the straight body. As the shape of the baffle plate, a plate shape, a columnar shape, and an elliptic column shape are preferably used. The size and shape of the baffle need not be defined in the above range.

In the present invention, slurry polymerization or bulk polymerization of α-olefin is carried out in the stirring tank 1 using the multistage stirring blades described above, and α
-An evaporating gas linear velocity (Ug) based on an empty tower in an agitation tank for evaporating an olefin monomer or a hydrocarbon-based solvent (dispersion medium) is in the range of 1.0 to 4.0 cm / sec, preferably 1.5 to 3 cm / sec. In the range of 0.5 cm / sec, the slurry flow rate at the slurry outlet nozzle of the stirring tank for circulating and extracting the α-olefin polymer slurry produced by polymerization is in the range of 0.5 to 3.0 m / sec, preferably 1 to 3.0 m / sec. 0.0 to 2.0 m / sec, more preferably 1.0 to 2.0 m / sec.
In the range of 1.5 m / sec, and the bubble content of the vaporized substance in the slurry at the slurry pump suction part [volume of bubble / (volume of bubble + volume of slurry) × 10
0] is 25% by volume or less, and particles produced by slurry polymerization or bulk polymerization are not substantially stagnated at the bottom of the polymerization tank, that is, stirring rotation at or above the particle suspension limit rotation speed (Njs or Njsg). And the liquid surface height (H) in the polymerization tank, the lower end of the straight body (lower Tangen)
0.9 to 1.0 × H on the basis of T.ia.
Concentration of solid particles in slurry at the position [upper concentration]
And the minimum agitation speed [the particle concentration equilibrium agitation speed required for the ratio of the solid particle concentration [lower concentration] in the slurry at the position of 0 to 0.1 × H to be constant [Nus or N
usg)] is operated under stirring speed conditions of 0.80 or more.

When the linear velocity of the evaporating gas based on the empty tower due to the evaporation of the α-olefin monomer or the hydrocarbon solvent (dispersion medium) is smaller than the lower limit (1.0 cm / sec), when the stirring tank having the same capacity is used, It is necessary to reduce the polymerization amount of the α-olefin monomer, or to increase the inner diameter (size) of the stirring tank in order to obtain the same polymerization amount of the α-olefin monomer, which is economically disadvantageous. .
On the other hand, the upper limit (4.0 cm /
If the mixing speed is longer than sec), the rotational speed of the particle concentration equilibrium stirring becomes excessive, and it is necessary to increase the setting of the rotational speed of the stirring. Since the bubble content of the evaporating substance in the slurry in the above increases, and the performance of the slurry pump deteriorates, the phenomenon of lowering the circulation amount of the slurry occurs, so it is necessary to select a slurry pump having an excessive capacity, which is economically disadvantageous. Not only that, if the bubble content further increases, the slurry pump tends to cause cavitation.

If the slurry flow rate at the nozzle for extracting the slurry from the polymerization tank is smaller than the lower limit (0.5 m / sec), solid particles in the slurry are deposited at the suction and discharge pipes provided in the slurry pump. In addition to causing the adhesion to the pipe, the actual pipe diameter is reduced, the pipe resistance is increased, and not only the phenomenon that the slurry circulation amount by the slurry pump is reduced, but also the clogging of the pipe is caused by the increase in the attached amount. Cause stable operation.

When the slurry flow rate is higher than the upper limit (3 m / sec), the bubble content in the slurry at the time of suction of the slurry pump increases, and the performance of the slurry pump decreases, causing a phenomenon of a decrease in the amount of circulating slurry and an excessive capacity of the slurry. It is necessary to select a slurry pump, which is not only economically disadvantageous, but also when the bubble content further increases, the slurry pump causes a cavitation phenomenon, which hinders stable operation of the slurry pump or causes a failure, thereby causing industrial problems. Not preferred.

When the bubble content of the evaporating substance in the slurry at the suction of the slurry pump is larger than the upper limit (25% by volume), the performance of the slurry pump deteriorates,
Further, if the bubble content increases to exceed 30% by volume, the danger of causing the cavitation phenomenon of the slurry pump increases, which hinders stable operation of the slurry pump and causes a failure, which is not industrially preferable.

The solid particle concentration [upper concentration] in the slurry at a position of 0.9 to 1.0 × H with respect to the lower end of the straight body (lower Tangential Line) with respect to the liquid level height (H) in the polymerization tank. And the minimum agitation rotation number [referred to as particle concentration equilibrium agitation rotation number (Nus or Nusg)] required to make the ratio of the solid particle concentration [lower concentration] in the slurry at the position of 0 to 0.1 × H constant. When the ratio of the stirring rotation speed becomes 1.0 or less, a difference starts to occur between the upper concentration and the lower concentration, and the stirring rotation speed and the particle equilibrium stirring rotation speed (Nus,
(Nusg) ratio of 0.8 or less, the difference between the upper and lower solid particle concentrations becomes remarkable.

The slurry outlet from the polymerization tank to the slurry pump is generally provided at the bottom of the polymerization tank or the lower part of the body, and under the above conditions, the slurry having a very high solid particle concentration can be obtained. To the slurry pump.

The concentration of solid particles in the slurry is 55% by weight.
Exceeding the limit causes an abrupt increase in slurry viscosity due to an increase in the concentration of solid particles, causing a decrease in the performance of the slurry pump.

Further, when the stirring speed is lower than the particle suspension limit stirring speed (Njs or Njsg) of the solid particles in the slurry, the solid particles are deposited and stagnated at the bottom of the polymerization tank, and a huge lump is formed by polymerization growth. Or may cause blockage of piping and pump casing. The formation or blockage phenomenon of a huge lump may cause a decrease in the performance of the slurry pump or cause a failure, which is not preferable.

According to the present invention, in the slurry polymerization or bulk polymerization of α-olefin, all or a part of the reaction heat generated in the reaction is used to evaporate the α-olefin or hydrocarbon-based solvent (dispersion medium) used for the polymerization. In a continuous polymerization method for an α-olefin polymer using a slurry pump for extracting or circulating a slurry of an α-olefin polymer generated in the polymerization tank and a slurry of the α-olefin polymer generated in the polymerization tank, the Prevent sedimentation and separation of solid particles,
In terms of improving the uniform mixing performance of the slurry and reducing the content of bubbles generated in the slurry due to the evaporation of the α-olefin or hydrocarbon-based solvent (dispersion medium) at the suction of the slurry pump, the stirring rotation speed is set. By setting the agitation rotation speed to balance the conflicting phenomena, the performance deterioration of the slurry pump is reduced, and the cavitation of the pump is prevented. -To provide a method for producing an olefin polymer.

As a result of many studies, the present inventors have found that, in the above-described combination of multi-stage blades, the minimum stirring rotation speed necessary to substantially prevent the solid particles in the slurry from remaining at the bottom of the stirring tank [ie, Particle floating limit minimum stirring speed (N
js)] is determined by the position and diameter of the three paddle blades disposed at the bottom of the stirring tank. In the case of a liquid-solid two-phase fluid in which gas does not pass through the slurry, the relationship is estimated by the following equation. I can do it.

Njs = S · ν− ^0.12 · [g · (ρs−ρ
l) / ρl] ^0.45 · dp ^0.4 · Ws ^0.13 / di ^0.85

The symbols used in the above equation are as follows. Njs: Limiting number of rotation of suspended solid particles under gas non-aeration condition [sec ^-1 ] S: Shape of stirring blade provided at bottom and diameter (D) of stirring tank and stirring from lower end of stirring blade provided at bottom A constant determined by the ratio (D / C) of the distance (C) to the bottom wall of the tank. Ν: kinematic viscosity of liquid [m ² / sec] ρs: density of solid [Kg / m ³ ] ρl: density of liquid [Kg / M ³ ] Ws: concentration ratio by weight of solid particles [solid / slurry] dp: particle diameter of solid particles [m] di: diameter of three paddle blades disposed at the bottom [m]

Further, a gas-liquid-solid 3 through which gas is passed.
Since the phase aeration and stirring tank is affected by gas aeration, it is necessary to correct Njs obtained by the above equation.

In this phenomenon, particles are buoyant by aeration of gas, but the agitating blade causes aeration due to the aeration and power of agitation load is reduced. It is considered that the effect of the lowering of the stirring power appears more remarkably than the buoyancy exerted on the particles.

Njsg = Njs · [1 + K · (Ug / U
t) ^0.2・ Rep ^0.4 ]

The symbols used in the above equation are as follows. Njsg: Limiting number of revolutions of floating solid particles under gas ventilation conditions [sec ^-1 ] K: Coefficient Ug: Base gas linear velocity of aerated gas in a stirred tank [m / sec] Ut: Static sedimentation speed of solid particles [m] / Sec] Rep: Particle-based Reynolds number = Ut · dp · ρav /
μav ρav: average density of slurry [Kg / m ³ ] μav: average viscosity of slurry [Kg / m / sec] dp: particle diameter of solid particles [m]

FIG. 4 shows the relationship between D / C and S when the above-mentioned multistage blade is used. FIG. 5 shows the relationship between the above estimation formula and actual measured values. When three paddle blades are mounted at a position where D / C is 10 or more, S is substantially constant at 1.5 to 2. If D / C is lower than 10, the particles will be in a poorly suspended state, and S will increase. The coefficient K of the correction estimation formula based on gas ventilation can be estimated using 0.02 to 0.05.

Next, the results of a study conducted by the present inventors on the rotational speed of the particle concentration equilibrium stirring are described.

In the above-described combination of multi-stage blades, as shown in FIG. 6, when the stirring rotation speed is low even in a non-ventilated state in which substantially no gas is passed, a slurry layer is formed in a portion of the stirring tank holding the slurry. The state is such that the solid particle concentrations in the upper and lower slurries cannot be uniformly mixed.

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 number of rotations of the stirring, and the concentration of the solid particles in the upper and lower portions becomes almost uniform. The minimum stirring speed required for the slurry layer to have a substantially uniform solid particle concentration is called the particle concentration equilibrium stirring speed (Nus).

It has been found from the study of the present inventors that the relationship can be estimated by the following equation.

Nus = K · ν− ^0.25 · [g · (ρs−ρ
l) / ρl] ^0.4 · dp ^0.47 · Ws ^0.22 / di ^0.8

The symbols used in the above equation are as follows. Nus: particle concentration equilibrium stirring speed under gas non-aeration condition [sec ^-1 ] K: constant determined by the shape of the arranged 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 [% by weight] dp: Particle diameter of solid particles [m] di: Diameter of arranged blades, number of arranged blades Average diameter of stage wing [m]

In a gas-liquid-solid three-phase aeration / stirring tank through which a gas is passed, it is necessary to correct Nus obtained by the above equation in order to consider the influence of gas aeration.

In this phenomenon, the gas is ventilated to exert a buoyancy on the particles. However, the agitating blade causes aeration due to the aeration and the power for agitation load is reduced. It is considered that the effect of the lowering of the stirring power appears more remarkably than the buoyancy exerted on the particles.

Nusg = Nus · [1 + K ′ · (Ug / Ut)] ^α

The symbols used in the above equation are as follows. Nusg: Particle concentration equilibrium agitation rotation speed [sec ^-1 ] under gas aeration conditions K ', α: Constant determined by shape of agitation blades arranged at the bottom Ug: Empty tower base gas linear velocity of aeration gas in agitation tank [ m / sec] Ut: Static settling velocity of solid particles [m / sec]

In many experiments by the present inventors, in the case of a multistage blade having a combination of three paddle blades and one turbine blade, K, K 'and α use the following numerical values regardless of the size of the blade. This made it possible to estimate the particle concentration equilibrium stirring rotation speed.

K = 0.25 to 0.35 K '= 40 to 50 α = 0.14 to 0.17

FIG. 7 shows the relationship between the particle concentration equilibrium stirring rotation speed obtained by the above equation and the actual measurement result.

Similarly, the present inventors have studied the change in the bubble content in the slurry inside the reaction tank and in the suction of the slurry pump when the gas was ventilated in the combination of the multistage blades described above. As shown in FIG. 9, it was found that the bubble content in the slurry was affected by the linear velocity of the gas flow, and furthermore, varied depending on the rotation speed of the stirring.

In the study of the present inventors on the power required for agitation, the reduction of slurry density due to the inclusion of bubbles in the slurry when gas is ventilated, and the rotation direction of the blade, which is often seen in the upper turbine type blade in particular, It was found that the power required for stirring decreased due to the phenomenon of including bubbles in the rear part (ie, generation of cavities).

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-β) / [Fr
^1.2 · D ^0.5 ] ^(-β)

The symbols used in the above equation are as follows. 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 stirring tank [m / se]
c] Fr: stirring fluid number Fr = n ² · di / g n: stirring rotation speed [sec ⁻¹ ] di: diameter of arranged blades, average diameter of arranged multiple-stage blades [m] g: gravity Acceleration 9.81 [m / sec ² ] D: diameter of stirring tank [m] β: constant

In the combination of two stages of turbine type blades and three paddle blades used in the present invention, K: 3 to 5, β: 1.0 to
It is possible to estimate Pgv using 1.3.

FIG. 10 shows the relationship between the calculated required stirring power (Pgv) obtained by the above equation and the actual measurement result.

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 holdup εg) is shown.

As described above, it can be seen from FIGS. 8 and 9 that the gas hold-up is related to the linear velocity of the aerated gas and the power required for stirring. Further, from the results of many experiments conducted by the present inventors, it was found that when the concentration of the solid particles in the slurry was increased, the gas hold-up was reduced, and the particle size of the solid particles in the slurry was slightly affected.

As a correlation equation of the gas hold-up in the stirring tank, the following estimation formula was obtained in consideration of the effect of the slurry concentration and the effect of the particle size of the solid particles, based on a model considering energy dissipation in a turbulent state.

Εg / (1−εg) = K · [(Pg / Q
g) / {ρ _av · (g · μ _av / ρ _av ) ^2/3 }] ^α · [Qg
/ (G · di ⁵ ) ^1/2 ] ^β · [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 / _Uturb ) ^-1/10

The symbols used in the above formula are as follows. K, α, β: coefficient εg: bubble content in slurry in the stirring tank [gas / (gas + slurry)] [-] Pg: power required for stirring under ventilation [W] Qg: gas ventilation amount [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 the arranged wings Average diameter of the arranged plural-stage wings [m] g: Acceleration of gravity 9.81 [m / sec ² ] Ut: Solid particles Stationary sedimentation velocity [m / sec] U _turb : Turbulence characteristic velocity 1.4 · (Np · n ³ · di ⁵ / V
Dp) ^(1/3) [m / sec] Np: power number n: stirring rotation speed [sec ^-1 ] V: volume of slurry layer in stirring tank [m ³ ] dp: average particle size of solid particles [ m]

The turbine type blade 2 stage + 3 used by the present inventors
In the combination of single paddle wings, K = 0.08 to 0.1
2, it is possible to estimate the bubble content using α = 3/15 and β = 4/5.

The gas hold-up in the suction of the slurry pump is performed by adjusting the gas hold-up in the stirring tank (in the εg tank) to the amount of slurry withdrawn from the slurry withdrawing nozzle of the stirring tank, the amount of evaporative gas in the stirring tank and the stirring power. The following formula was obtained.

Εg (out of the tank) = K ′ · εg (inside the tank) ^{α ′} ·
(Ql / Qg) ^γ · (Pav / Pgv) ^δ · Frg ^κ ·
(Ρ _av / ρg) ^-0.01

The symbols used in the above equation are as follows. K ', γ, δ, κ: coefficient εg (in the tank): bubble content rate in the slurry in the stirring tank [gas / (gas + slurry)] [-] εg (out of the tank): in the slurry at the suction of the slurry pump Ql: Slurry withdrawal flow rate [m ³ / sec] Qg: Gas ventilation rate [m ³ / sec] Pav: Gas ventilation power (Pav = ρ _av ·) Qg ・ H / V ・
g / gc / 0.102 ≒ ρ _av · Ug / 0.102) [W
/ M ³ ] Pgv: Power required for stirring under aeration per unit volume [W /
m ³ ] Frg: Aeration fluid number (Frg = Ug ² / di / g)

The turbine type blade 2 stage + 3 used by the present inventors
In the combination of the paddle blades, K ′ = 20 to 45 α ′ = 1.6 to 2.0 γ γ = 0.6 to 1.0 δ = 0 to −0.1 κ κ = 0.1 to 0.25 It can be used to estimate the bubble content.

[0107] In the stirring tank and in the suction of the slurry pump
The calculated value of the bubble content (εg) obtained by the above estimation formula and the actual value
The relationship between the measurement results is shown in FIGS.

The empirical formulas for estimating the floating limit stirring speed of particles, the stirring speed for particle concentration equilibrium, the power required for stirring under gas ventilation, and the bubble content in the stirring tank and in the suction of the slurry pump have been described. The invention is not limited to these.

As described above, in the method for producing a propylene polymer by slurry polymerization or bulk polymerization, all or part of the heat of polymerization is utilized by utilizing the latent heat of vaporization by evaporation of the propylene monomer or hydrocarbon solvent (dispersion medium). When using a slurry pump for extracting or circulating the slurry in the reaction tank in the reaction tank attached to the heat removal equipment, in order not to lower the performance of the slurry pump,
It is necessary to keep the content of bubbles in the slurry at the suction of the slurry pump low, and to make the concentration of the solid particles in the slurry as uniform as possible, for which purpose the mixing performance of the solid particles in the slurry is improved, and It is important to reduce the content of bubbles in the slurry.

Hereinafter, the present invention will be described with reference to Examples and Comparative Examples.

[0111]

EXAMPLES The following examples and comparative examples were carried out using the following reaction apparatus and measuring apparatus.

A reflux condenser 7 for condensing and liquefying the gas evaporated in the reaction tank 1 as shown in FIG. 15, a drum 8 holding the condensed liquid, and a pump 9 for supplying the recovered liquid to the reaction tank 1 again And a heater 10 for heating and evaporating the liquid is provided as an accessory facility, and a slurry discharge nozzle having an inner diameter of 53.5 mm is provided at the bottom of the reaction tank.
A slurry pump 11 of 39 kg / m / kg capable of controlling the slurry circulation rate at 10 to 20 m ³ / h is connected to the nozzle by a pipe, and most of the slurry is discharged from the discharge line of the slurry pump 11 to the reaction tank 1. An inner diameter 75 that circulates and a part of which can be extracted to the next process is provided as an auxiliary equipment.
A stirring shaft 2 is disposed at the center of a vertical stirring tank 1 having a height of 0 mm, a height of 1370 mm and a capacity of 0.66 m ³ , and the distance from the bottom wall surface of the stirring tank to the lower end of the blade is 75 mm. , Three paddle blades 3 having d1 = 436 mm, b1 = 65 mm, a retraction angle (γ) of about 30 °, and an ascending angle (δ) of about 15 ° are arranged at intervals of about 320 mm above each. Two stages of turbine type blades 4 having d2 = 300 mm, b2 = 60 mm, and l = 76 mm and having a blade angle of about 45 ° downward (θ) were arranged.

The stirring shaft 2 is provided at 0 to 36
It is rotated by an inverter motor (motor) whose rotation speed can be changed within a range of 0 r / m.

The measuring apparatus 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 stirring shaft 2 outside the tank.

An orifice type differential pressure flow meter (C) is provided between the stirring tank 1 and the reflux condenser 7 to measure the linear evaporation speed of the gas in the empty tower base inside the stirring tank 1.

As means for measuring the concentration of solid particles in the slurry inside the reactor, the lower end of the straight body of the reactor (lower Tang)
50mm and 800mm from the initial line)
Sampling pipes (D1) and (D2) and a valve were provided at a position inserted 200 mm from the side wall of the stirring tank above, and the solid particle concentration was determined by sampling.

The discharge of the slurry pump 11 installed in the bottom extraction line of the stirring tank 1 was carried out by using a radiation type densitometer (E
1) was installed, and the density of the solid in the slurry withdrawn from the bottom of the stirring tank was determined by measuring the slurry density.

The content (εg) of bubbles in the slurry inside the reactor was determined by arranging two radiation type densitometers (E2) and (E3) at approximately the same height as the sampling tube.
The average density of the slurry containing air bubbles was measured, and the air bubble content was calculated by the following equation using the solid particle concentration in the slurry which was separately obtained by sampling.

The radiation type density meter (E4) is also used for suction of the slurry pump 11 disposed in the slurry outlet line at the bottom of the reactor.
Is installed, the average density of the slurry containing bubbles in the suction of the slurry pump is measured in the same manner as described above, and the solid particle concentration in the slurry obtained by the radiation type densitometer (E1) separately discharged from the slurry pump is used in the following equation. The bubble content was calculated.

Ρ _Slurry = 100 / ｛[solid] / ρ
_s + (100− [solid]) / ρ _l ) εg = (ρ _slurry −ρ _av ) / (ρ _slurry −ρ _g ) × 10
0

The symbols used in the above equation are as follows. ρ _Slurry : Average density of slurry (liquid and solid) not containing bubbles [solid]: Concentration of solid particles in slurry not containing bubbles ρ _s : Density of solid ρ _l : Density of liquid ρ _av : Measured by radiation densitometer Average density ρ _g including gas bubbles: Gas density of evaporative gas

The performance of the slurry pump is measured by measuring the head of the slurry pump using a diaphragm type differential pressure gauge (F) between the discharge and the suction of the slurry pump, and the circulation amount of the pump is set at the discharge of the pump. Using a venturi type differential pressure flow meter (G), the flow rate was controlled by a slurry flow rate control valve (H) installed at the return of the circulation line.

Example 1 In the reactor shown in FIG. 15, the liquid volume was 0.44 m ³ (L / D = 1.16), the polymerization temperature was 70 ° C.
Pressure 32.5 Kg / cm ² G, hydrogen concentration 5 mol%, stirring rotation speed 250 r / m, gas evaporation 1.8 Ton / h
(Evaporation linear velocity 1.5 cm / sec) Supply amount of solid catalyst 1.2
The bulk continuous polymerization of polypropylene was performed under the conditions of g / h and a supply amount of propylene of 125 kg / h.

At this time, the circulation amount of the slurry pump was 10 m ³
/ H (slurry extraction speed 1.24 m / sec).

In this operation, the power required for stirring is 0.5
5 KW (Pv = 1.6 KW / m ³ ), and the polypropylene particle concentration obtained by sampling the upper and lower parts of the reaction tank was almost uniform at 40% by weight in the upper part and 41% by weight in the lower part.
The bubble content in the reaction tank was 21% by volume as calculated from the radiation type densitometer, the bubble content at the suction part of the slurry pump was 19% by volume, and the differential pressure of the slurry pump measured by the differential pressure gauge was 1.75 Kg /. cm ² , 34
Kg · m / Kg, a continuous continuous operation was possible for 36 hours under the condition of a head reduction rate of about 6.0% with respect to the slurry pump head of 36 Kg · m / Kg when no bubbles were contained.

The particles obtained by continuous polymerization have an average particle diameter of 60.
0 μm, the catalyst efficiency is 43,200 g-polypropylene / g-catalyst, and the polypropylene has an average of 52 Kg /
h of production rate.

A part of atactic polypropylene, which is a by-product of polymerization, is dissolved in propylene, which is a liquid.
From the dissolved concentration, the viscosity of the liquid was estimated to be 2.0 to 2.5 centipoise, and the calculated particle suspension limit stirring speed under the operating conditions was 129 r / m, and the particle concentration equilibrium stirring rotation speed was 190 r / m. m.

(Example 2) The amount of gas evaporation was 3.5 Ton
/ H (evaporation linear velocity 3.0 cm / sec), except that bulk continuous polymerization of polypropylene was performed under the same conditions as in Example 1.

At this time, the circulation amount of the slurry pump was 10 m ³
/ H (slurry extraction speed 1.24 m / sec).

In this operation, the power required for stirring is 0.4
6KW (Pv = 1.44 KW / m ³ ), the polypropylene particle concentration by sampling at the top and bottom of the reaction tank was almost uniform at 39.5% by weight in the upper part and 40% by weight in the lower part. The calculated bubble content in the reaction tank was 27.6% by volume, the bubble content at the suction part of the slurry pump was 22.0% by volume, and the differential pressure of the slurry pump measured by a differential pressure gauge was 1.68 kg / cm ² . In terms of a head, it is 33.1 Kg · m / Kg, which is about 8.30 kg / m / Kg of the slurry pump head when no bubbles are contained.
A continuous operation could be stably performed for about 24 hours under the condition of the head reduction rate of 0%.

The particles obtained by continuous polymerization have an average particle size of 49.
0 μm, the efficiency of the catalyst is 41,000 g-polypropylene / g-catalyst, and the polypropylene has an average of 49 kg / g
h of production rate.

A part of atactic polypropylene, which is a by-product of polymerization, is dissolved in propylene, which is a liquid.
From the dissolved concentration, the viscosity of the liquid was estimated to be 2.0 to 2.5 centipoise, and the calculated particle suspension limit stirring speed under the operating conditions was 130 r / m, and the particle concentration equilibrium stirring speed was 210 r / m. m.

(Example 3) The stirring rotation speed was from 250 to 30.
Bulk continuous polymerization of polypropylene was performed under the same conditions as in Example 1 except that the rate was changed to 0 r / m.

At this time, the circulation amount of the slurry pump was 10 m ³
/ H (slurry extraction speed 1.24 m / sec).

In this operation, the power required for stirring is 0.9.
3KW (Pv = 3.43KW / m ³ ), the polypropylene particle concentration by sampling at the top and bottom of the reaction tank was almost uniform at 40.2% by weight in the upper part and 41.3% by weight in the lower part. Is 22.5% by volume, the bubble content at the suction part of the slurry pump is 23.2% by volume, and the differential pressure of the slurry pump measured by a differential pressure gauge is 1.65 Kg / cm. ^When converted to a head by ² , the head reduction rate of about 11.0% and the head reduction rate are slightly higher than the slurry pump head of 36 kg / m / Kg which is 32.0 Kg · m / Kg and contains no air bubbles. However, continuous operation was stable for about 20 hours.

The particles obtained by continuous polymerization have an average particle size of 50.
0 μm, the efficiency of the catalyst is 42,700 g-polypropylene / g-catalyst, and the polypropylene has an average of 51 Kg /
h of production rate.

A part of atactic polypropylene, which is a by-product of polymerization, is dissolved in propylene, which is a liquid.
From the dissolved concentration, the viscosity of the liquid was estimated to be 2.0 to 2.5 centipoise, and the calculated particle suspension limit stirring speed under the operating conditions was 128 r / m, and the particle concentration equilibrium stirring speed was 190 r / m. m.

(Comparative Example 1) Bulk continuous polymerization of polypropylene was carried out under the same conditions as in Example 3 except that the gas evaporation amount was increased from 1.75 to 3.5 Ton / h (evaporation linear velocity: 3.0 cm / sec). went.

At this time, the circulation amount of the slurry pump was 10 m ³
/ H (slurry extraction speed 1.24 m / sec).

In this operation, the power required for stirring is 0.7
4 KW (Pv = 2.38 KW / m ³ ), the polypropylene particle concentration by sampling at the top and bottom of the reaction tank was almost uniform at 38.2 wt% in the upper part and 39.3 wt% in the lower part. The bubble content in the reaction tank was calculated to be 30.1% by volume, the bubble content at the suction part of the slurry pump was 26.5% by volume, and the differential pressure of the slurry pump measured by a differential pressure gauge was 1.46 Kg / cm. ^When converted to a head at ² , the head reduction rate is about 21.0% compared to 36 Kg · m / Kg of the slurry pump head without bubbles at 28.5 Kg · m / Kg, and the cavitation phenomenon of the slurry pump However, continuous operation was stopped in seven hours because the circulation flow rate gradually decreased and the flow rate fluctuated and became unstable.

The particles obtained by continuous polymerization have an average particle size of 49.
0 μm, the efficiency of the catalyst is 40,000 g-polypropylene / g-catalyst, and the polypropylene has an average of 48 kg / polypropylene.
h of production rate.

A part of atactic polypropylene, which is a by-product of polymerization, is dissolved in propylene, which is a liquid.
From the dissolved concentration, the viscosity of the liquid was estimated to be 2.0 to 2.5 centipoise, and the calculated particle suspension limit stirring speed under the operating conditions was 130 r / m, and the particle concentration equilibrium stirring speed was 210 r / m. m.

(Example 4) The circulation amount of the slurry pump was set to 1
0 to 14 m ³ / h (slurry withdrawal speed of 1.73 m
/ Sec), except that the bulk continuous polymerization of polypropylene was performed under the same conditions as in Example 1.

In this operation, the power required for stirring is 0.5
5 KW (Pv = 1.6 KW / m ³ ), the concentration of polypropylene particles by sampling at the top and bottom of the reaction tank was almost uniform at 41.2 wt% in the upper part and 41.5 wt% in the lower part. Is 20.7% by volume, the bubble content at the suction part of the slurry pump is 25.0% by volume, and the differential pressure of the slurry pump measured by a differential pressure gauge is 1.63 Kg / cm. ^When converted to a head by ² , the head reduction rate of about 12.5% and the head reduction rate are slightly higher than the slurry pump head of 36 Kg · m / Kg at 31.5 Kg · m / Kg and without bubbles. However, continuous operation was stable for about 18 hours.

The particles obtained by continuous polymerization have an average particle size of 50.
0 μm, the catalyst efficiency is 43,200 g-polypropylene / g-catalyst, and the polypropylene has an average of 52 Kg /
h of production rate.

[0146] A part of atactic polypropylene, which is a by-product of polymerization, is dissolved in propylene, which is a liquid.
From the dissolved concentration, the viscosity of the liquid was estimated to be 2.0 to 2.5 centipoise, and the calculated particle suspension limit stirring speed under the operating conditions was 129 r / m, and the particle concentration equilibrium stirring speed was 191 r / m. m.

(Comparative Example 2) Bulk continuous polymerization of polypropylene was carried out under the same conditions as in Example 4 except that the gas evaporation amount was increased from 1.75 to 3.5 Ton / h (evaporation linear velocity 3.0 cm / sec). went.

At this time, the circulation amount of the slurry pump was 14 m ³
/ H (slurry withdrawal speed of 1.73 m / sec).

In this operation, the power required for stirring is 0.4
6KW (Pv = 1.44KW / m ³ ), the polypropylene particle concentration by sampling at the top and bottom of the reaction tank was almost uniform at 39.1% by weight at the upper part and 39.3% by weight at the lower part. The bubble content in the reaction tank was calculated to be 27.6% by volume, the bubble content in the suction part of the slurry pump was 28.8% by volume, and the differential pressure of the slurry pump measured by a differential pressure gauge was 1.37 Kg / cm. ^When converted to a head by ² , the head reduction rate is about 25% compared to 36Kg · m / Kg of the slurry pump head without bubbles at 27.0 Kg · m / Kg, and the cavitation phenomenon of the slurry pump is Although it did not occur, the continuous operation was stopped since about 4 hours after the start of the polymerization reaction, the circulating flow rate was drastically reduced and the flow rate became unstable and the operation became unstable.

The particles obtained by continuous polymerization have an average particle size of 49.
0 μm, the efficiency of the catalyst is 41,000 g-polypropylene / g-catalyst, and the polypropylene has an average of 49 kg / g
h of production rate.

A part of atactic polypropylene, which is a by-product of polymerization, is dissolved in propylene, which is a liquid.
From the dissolved concentration, the viscosity of the liquid was estimated to be 2.0 to 2.5 centipoise, and the calculated particle suspension limit stirring speed under the operating conditions was 130 r / m, and the particle concentration equilibrium stirring speed was 209 r / m. m.

Example 5 The operation of Comparative Example 2 was unstable, and the operation was stopped in a short time.
The bulk continuous polymerization of polypropylene was performed under the same conditions as in Comparative Example 2 except that the speed was reduced from 0 to 200 r / m.

At this time, the circulation amount of the slurry pump was 14 m ³
/ H (slurry withdrawal speed of 1.73 m / sec).

In this operation, the power required for stirring is 0.2
6 KW (Pv = 0.78 KW / m ³ ), and the polypropylene particle concentration by sampling at the top and bottom of the reactor was 29.5 wt% at the top and 38.0 wt% at the bottom, with a slight difference between the top and bottom. However, the bubble content in the reaction tank calculated by the radiation type densitometer was 23.0% by volume, the bubble content at the suction part of the slurry pump was 23.5% by volume, and the differential pressure of the slurry pump measured by the differential pressure gauge Is 1.60 Kg / c
When converted to a head in m ² , it is 32.0 Kg · m / Kg, and the head of the slurry pump when no bubbles are contained is 36 Kg · m.
/ Kg, a decrease rate of about 11% and the decrease rate were slightly higher, but continuous operation could be performed stably for about 20 hours.

The particles obtained by continuous polymerization have an average particle size of 48.
5 μm, the efficiency of the catalyst is 39,200 g-polypropylene / g-catalyst, and the polypropylene has an average of 46 Kg /
h of production rate.

The catalyst efficiency and production rate were slightly reduced due to a slight decrease in the concentration of polypropylene particles in the upper part of the reactor.

In the liquid propylene, a part of the atactic polypropylene by-produced by the polymerization is dissolved.
From the dissolved concentration, the viscosity of the liquid is estimated to be 2.0 to 2.5 centipoise, and the calculated particle suspension limit stirring speed under the operating conditions is 129 r / m, and the particle concentration equilibrium stirring speed is 207 r / m. m and the ratio of the stirring rotation speed to the particle concentration equilibrium stirring rotation speed was 0.97.

(Comparative Example 3) Bulk continuous polymerization of polypropylene was performed under the same conditions as in Example 5 except that the amount of gas evaporation was increased from 3.5 to 5.26 Ton / h (evaporation linear velocity 4.5 cm / sec). went.

At this time, the circulation amount of the slurry pump was 14 m ³
/ H (slurry withdrawal speed of 1.73 m / sec).

In this operation, the power required for stirring was 0.2
It was 3 KW (Pv = 0.73 KW / m ³ ), and the polypropylene particle concentration by sampling at the top and bottom of the reaction tank was 22 wt% at the top and 36.0 wt% at the bottom, with a slight difference between the top and bottom. The bubble content in the reaction tank calculated from the radiation type densitometer was 29.6% by volume, the bubble content at the suction part of the slurry pump was 27.5% by volume, and the differential pressure of the slurry pump measured by the differential pressure gauge was 1 When converted to a head at .46 Kg / cm ² , the slurry pump head is 36 Kg · m / K at 29.5 Kg · m / Kg and contains no air bubbles.
The head drop rate and drop rate of about 18% were high with respect to g, and the cavitation phenomenon of the slurry pump did not occur. However, since the circulation flow rate had a tendency to decrease and the flow rate fluctuation was unstable, the operation became unstable. After the operation for about 6 hours, the continuous operation was stopped.

The particles obtained by continuous polymerization have an average particle size of 48.
0 μm, the efficiency of the catalyst is 37,200 g-polypropylene / g-catalyst, with an average of 45 kg / polypropylene.
h of production rate.

Since the concentration of polypropylene particles in the upper part of the reactor was reduced, the catalyst efficiency and the production rate were about 1
It decreased about 0%.

A part of atactic polypropylene, which is a by-product of polymerization, is dissolved in propylene, which is a liquid.
From the dissolved concentration, the viscosity of the liquid was estimated to be 2.0 to 2.5 centipoise, and the calculated particle suspension limit stirring speed under the operating conditions was 130 r / m, and the particle concentration equilibrium stirring speed was 218 r / m. m and the ratio of the stirring rotation speed to the particle concentration equilibrium stirring rotation speed was 0.92.

(Comparative Example 4) Compared to Example 5, the gas evaporation amount was 3.5 to 1.75 Ton / h (evaporation linear velocity 1.5c
m / sec), and the stirring rotation speed is 200 to 150 r.
/ M, and the bulk continuous polymerization of polypropylene was performed under the same conditions as in Example 5.

At this time, the circulation amount of the slurry pump was 14 m ³
/ H (slurry withdrawal speed of 1.73 m / sec).

In this operation, the power required for stirring is 0.1
4 KW (Pv = 0.39 KW / m ³ ), and the polypropylene particle concentration by sampling at the top and bottom of the reaction tank was 0 wt% in the upper part and 56 wt% in the lower part. A sudden decrease and fluctuation phenomenon of the circulation flow rate, which is considered to be due to an increase in the concentration of the polypropylene solid particles, occurred.
Emergency stop measures were taken to stop.

At this time, although not accurate, the bubble content in the reaction tank was 16.5% by volume calculated from the radiation density meter, and the bubble content in the slurry pump suction part was 15.
5% by volume, the differential pressure of the slurry pump measured by a differential pressure gauge was 1.20 Kg / cm ^2, which was 21.5 K in terms of head.
The head reduction rate is about 28% higher than the head of 36 kg / m / Kg of the slurry pump when g · m / Kg and contains no air bubbles, and the head reduction rate is high. It is thought to be due to a sudden increase in the concentration of polypropylene solid particles.

Although the polymerization was carried out for a short time, the obtained particles were not accurate, but had an average particle diameter of 490 μm, but large quantities of 10 to 50 mm in size came out of the casing of the slurry pump.

A part of atactic polypropylene, which is a by-product of polymerization, is dissolved in propylene, which is a liquid.
From the dissolved concentration, the viscosity of the liquid is estimated to be 2.0 to 2.5 centipoise, and the calculated particle suspension limit stirring speed under the operating conditions is 127 r / m, and the particle concentration equilibrium stirring rotation speed is 200 r / m. m and the ratio of the stirring rotation speed to the particle concentration equilibrium stirring rotation speed was 0.75.

(Example 6) In order to confirm the limit of the amount of slurry withdrawn, the circulation amount of the slurry pump was set to 16 m ³ /
h (slurry withdrawal speed 1.98 m / sec), except that the bulk continuous polymerization of polypropylene was performed under the same conditions as in Example 5.

In this operation, the power required for stirring was 0.2
6 KW (Pv = 0.78 KW / m ³ ), and the polypropylene particle concentration by sampling at the top and bottom of the reactor was 32.5 wt% at the top and 37.4 wt% at the bottom, with a slight difference between the top and bottom. However, the bubble content in the reaction tank calculated by a radiation type densitometer was 24.0% by volume, the bubble content at the suction part of the slurry pump was 24.5% by volume, and the differential pressure of the slurry pump measured by the differential pressure gauge Is 1.59 kg / c
When converted to a head in m ² , the slurry pump head is 31.7 Kg · m / Kg and contains no air bubbles, and the head is 36 Kg · m.
The head reduction rate of about 12% with respect to / Kg and the head reduction rate were slightly higher, but continuous operation could be performed stably for about 17 hours.

The particles obtained by continuous polymerization have an average particle size of 48.
0 μm, the efficiency of the catalyst is 39,000 g-polypropylene / g-catalyst, and the polypropylene has an average of 47 Kg /
h of production rate.

Since the concentration of the polypropylene particles in the upper part of the reactor was slightly lowered, the catalyst efficiency and the production rate were slightly lowered.

A part of atactic polypropylene, which is a by-product of polymerization, is dissolved in propylene, which is a liquid.
Based on the dissolved concentration, the viscosity of the liquid was estimated to be 2.0 to 2.5 centipoise, and the calculated particle suspension limit stirring speed under the operating conditions was 127 r / m, and the particle concentration equilibrium stirring rotation speed was 205 r / m. m and the ratio of the stirring rotation speed to the particle concentration equilibrium stirring rotation speed was 0.98.

(Comparative Example 5) The slurry withdrawal amount was further increased as compared with Example 6, and the circulation amount of the slurry pump was increased to 18 m.
Bulk continuous polymerization of polypropylene was carried out under the same conditions as in Example 6, except that the rate was increased to ³ / h (slurry withdrawal speed: 2.23 m / sec).

In this operation, the power required for stirring was 0.2
6KW (Pv = 0.78KW / m ³ ), and the polypropylene particle concentration by sampling at the top and bottom of the reaction tank was 32.0% by weight at the upper part and 37.6% by weight at the lower part. However, the bubble content in the reaction tank calculated from the radiation type densitometer was 25.3% by volume, the bubble content at the slurry pump suction part was 28.4% by weight, and the differential pressure of the slurry pump measured by the differential pressure gauge Is 1.36Kg / c
When converted to a head in m ² , the slurry pump head is 27.2 Kg · m / Kg and contains no bubbles, and the head is 36 Kg · m.
/ Kg about 25% of the head drop rate and the head drop rate were high and did not lead to the cavitation phenomenon of the slurry pump, but the circulation flow rate was on the decline and the flow rate fluctuated greatly, resulting in unstable operation. After driving for about 8 hours,
Continuous operation was stopped.

The particles obtained by continuous polymerization have an average particle size of 48.
5 μm, the efficiency of the catalyst is 39,200 g-polypropylene / g-catalyst, and the polypropylene has an average of 47 Kg /
h of production rate.

The catalyst efficiency and production rate were slightly reduced due to a slight decrease in the concentration of polypropylene particles in the upper part of the reactor.

In the liquid propylene, a part of atactic polypropylene by-produced by polymerization is dissolved.
From the dissolved concentration, the viscosity of the liquid is estimated to be 2.0 to 2.5 centipoise, and the calculated particle suspension limit stirring speed under the operating conditions is 129 r / m, and the particle concentration equilibrium stirring speed is 207 r / m. m and the ratio of the stirring rotation speed to the particle concentration equilibrium stirring rotation speed was 0.97.

As described above, some of the examples and comparative examples have been described. The relationship between the bubble content at the suction of the slurry pump and the reduction in the performance of the slurry pump obtained by the present inventors as a result of a number of studies has been described. FIG. 13 shows the bubble content in the suction of the slurry pump, the circulation amount of the slurry pump, the change over time of the head, and the change over time of the slurry pump in the model experiment without the polymerization reaction performed to confirm the cavitation phenomenon of the slurry pump. FIG. 14 shows the relationship between cavitation phenomena.

[0181]

EFFECT OF THE INVENTION A polymerization method in which an α-olefin monomer or a hydrocarbon solvent (dispersion medium) is evaporated by slurry polymerization or bulk polymerization of α-olefin to remove the heat of polymerization and stirring heat by latent heat of evaporation. In the case of using a slurry pump for extraction or circulation of the slurry, the stirring pump is set to prevent the performance of the slurry pump from decreasing due to the increase in the content of bubbles in the slurry due to the evaporation of gas and the cavitation phenomenon, and the heat exchanger is used. By setting the settings appropriately, the performance of the slurry pump was maintained, and it was possible to stably perform continuous polymerization.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a reaction tank.

2A is a plan view and FIG. 2B is a side view showing three paddle wings.

3A is a plan view showing a turbine type blade, and FIG.
Is a side view

FIG. 4 is a graph showing a relationship between a mounting position of the three paddle blades and a coefficient S in an equation for estimating a critical speed of floating particles.

FIG. 5 is a graph showing the relationship between the measured value of the particle rotation limit stirring speed and the estimated calculated value.

FIG. 6 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. 7 is a graph showing a relationship between a measured value of a particle concentration equilibrium stirring speed and an estimated calculated value.

FIG. 8 is a graph showing an example of a measurement result of a relationship between a gas ventilation linear velocity and a bubble content in a reaction tank.

FIG. 9 is a graph showing an example of a measurement result of a relationship between a gas ventilation linear velocity and a bubble content in a suction part of a slurry pump.

FIG. 10 is a graph showing the relationship between the measured value of the required power for stirring under gas aeration conditions and the estimated calculated value.

FIG. 11 is a graph showing a relationship between a measured value of a bubble content rate in a reaction tank and an estimated calculated value.

FIG. 12 is a graph showing a relationship between a measured value and a calculated value of a bubble content rate in a suction part of a slurry pump.

FIG. 13 shows an example of a measurement result of a bubble content rate and a slurry pump head drop rate at the time of suction of a slurry pump.

FIG. 14 is a graph showing an example of the measurement results of the change over time in the bubble content and the slurry pump performance.

FIG. 15 is an explanatory view showing an example of an apparatus for implementing the present invention.

[Explanation of symbols]

 1: Polymerization tank 2: Stirring shaft 3, 3a: Three paddle blades 4: Turbine blade 4b: Blade plate 5: Baffle plate 7: Reflux condenser 8: Recovered liquid drum 9: Recovered liquid pump 10: Heater 11: Slurry Cooler 12: Electric motor A: Torque motor B: Photoelectric tachometer C: Orifice type differential pressure flow meter D1, 2: Sampling tube E1-4: Radiation type density meter F: Diaphragm type differential pressure meter G: Venturi type differential pressure flow meter H: Slurry flow control valve

Continued on the front page (72) Inventor Yoshihiro Yamamoto 3-10, Utsudori, Kurashiki-shi, Okayama Prefecture F-term (reference) 4J011 DA02 DB19 DB32 FA01 FB07 FB11 FB16 FB17 HB03 HB07 HB15 HB22 4J100 AA02P AA03P AA04P AA07P AA16P AA19P CA01 CA10 FA09 FA18 FA19 FA27 FA47

Claims (5)

[Claims] Claims: 1. An α-olefin is subjected to slurry polymerization or bulk polymerization using a polymerization tank in the presence of a stereoregular catalyst,
In a method for producing an α-olefin polymer in which the heat of polymerization generated in the polymerization is removed by utilizing latent heat due to evaporation of an evaporating substance, the slurry in the polymerization tank is extracted using a slurry pump while removing the evaporating substance. Evaporation linear velocity (Ug) based on an empty tower in the polymerization tank is 1.0 to 4.0 cm / sec.
, The bubble content of the vaporized substance in the slurry at the suction part of the slurry pump [bubble volume / (bubble volume + slurry volume) × 100] is 25% by volume or less, and the liquid level in the polymerization tank (H), the solid particle concentration [upper concentration] in the slurry at a position of 0.9H to 1.0H with respect to the lower end of the straight body portion of the polymerization tank and the solids concentration in the slurry at a position of 0 to 0.1H An α-olefin which is operated in a state where the ratio of the stirring rotation speed to the minimum stirring rotation speed required for the particle concentration [lower concentration] ratio to be constant is 0.80 or more. A method for producing a polymer. 2. The method for producing an α-olefin polymer according to claim 1, wherein the slurry in the polymerization tank is withdrawn using a slurry pump, and at least a part of the slurry is circulated to the polymerization tank. 3. The method for producing an α-olefin polymer according to claim 1, wherein the slurry withdrawing speed at the slurry withdrawing port of the polymerization tank is in the range of 0.5 to 2.0 m / sec. 4. The stirring speed in the polymerization tank is higher than the particle rotation limit stirring speed in a state where particles generated by the polymerization are not substantially stagnated at the bottom of the polymerization tank. 3. The method for producing an α-olefin polymer according to item 1. 5. The polymerization tank has a stirring shaft provided with paddle blades and turbine blades, and the paddle blade is disposed at the bottom of the stirring shaft, and has a shape ranging from the center of the stirring shaft to the tip of the blade. Is a three-paddle blade having a sweepback angle (γ) increasing backward in the range of 25 to 50 ° with respect to the rotation direction of the shaft and a rising angle (δ) of 10 to 20 °, the diameter of the blade ( The ratio (d1 / D) between d1) and the diameter (D) of the stirring tank is in the range of 0.5 to 0.6, and the ratio (b1) between the blade width (b1) and the blade diameter (d1). / D1) is in the range of 0.1 to 0.2, and the turbine blade is provided in one or two or more stages above the paddle blade. Indicates that the ratio (d2 / D) of the diameter (d2) of the turbine blade to the diameter (D) of the stirring vessel is in the range of 0.4 to 0.5, The ratio of the width (b2) and turbine blades of a diameter (d2) (b2 / d2) is 0.15
0.25, and the ratio (l / d2) of the blade length (l) to the diameter (d2) of the turbine blade is 0.2 to 0.1.
In the range of 3, four to six blades having an inclination angle (θ) of 30 to 60 ° are provided, and the paddle blade has a distance (C) between the lower end of the blade and the bottom of the stirring tank. 5. The production of an α-olefin polymer according to any one of claims 1 to 4, comprising a polymerization apparatus disposed at a position where the ratio (C / D) of the diameter (D) of the stirring tank to the diameter (D) is 0.2 or less. Method.