JPH0333161B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a polymerization reactor, in particular a reactor suitable for suspension polymerization.

Among polymer production methods, suspension polymerization has many advantages as follows.

The low viscosity of the reaction medium facilitates mass transfer and mixing even at high polymer concentrations.

Therefore, the reactor volume per unit yield of polymer produced can be reduced.

Particularly when a liquid monomer is used as the reaction medium, recovery of the medium is not necessary, and energy consumption can be significantly reduced.

However, suspension polymerization methods also have certain drawbacks. For example, the produced polymer adheres to the reactor wall and stirring blade surface that are in contact with the reaction medium, and over time, it becomes thick and even scales, which not only makes it impossible to carry out a uniform polymerization reaction, but also makes stirring difficult. This can lead to accidents such as blockage of the reaction vessel. This situation is particularly noticeable when the polymer produced is a rubbery material, and various solutions have therefore been proposed.

For example, Japanese Patent Publication No. 45-34830 and Japanese Patent Publication No. 46-41605 describe a method in which a solvent is added to the reaction medium to make it difficult for polymer particles to adhere to the reaction medium. However, this method requires the steps of solvent separation, purification, and recovery, which is undesirable in terms of energy consumption.
Further, Japanese Patent Publication No. 47-44877 describes a reaction apparatus having a structure for scraping off polymers adhering to the walls of a reaction vessel and the surfaces of stirring blades. However, this reactor has an extremely complicated structure, making it difficult to widely use it for industrial purposes.

In view of this situation, the present inventors conducted intensive research to develop a polymerization reaction apparatus that can prevent polymer particles from adhering to the walls of the reaction vessel and the surface of the stirring blades. It was discovered that the adhesion of polymer particles can be prevented and a uniform polymer reaction can be carried out stably by this method, and the present invention has been achieved based on this discovery.

That is, the polymerization reaction apparatus of the present invention has a stirring blade provided with paddle blades in multiple stages in a cylindrical container, and a baffle plate located in multiple stages between the paddle blades, and the paddle blades have a twist angle (θ) of 90. The twist part of ゜ or more is 1
This is a polymerization reaction apparatus characterized by having the above.

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

In the example of the apparatus of the present invention shown in FIG. 1, 1 is a cylindrical reaction vessel, which is sealed with an upper lid 2. The side wall of the container 1 is surrounded by a jacket 5, which has a supply port 3 and a discharge port 4 for a heat medium or a coolant, and is used to heat or cool the container 1 as required.

6 is a stirring blade, which is connected to a stirring shaft 8 that is connected to a stirring drive electric motor 7 placed on the upper lid 2 and extends toward the bottom of the container along the axis of the container 1; It is composed of multi-stage paddle wings 9 that are attached and extend in the width direction of the container 1. In the example shown in FIG. 1, the paddle blades 9 are provided in four stages, with two paddle blades per stage, at substantially symmetrical positions with respect to the stirring shaft 8.

The paddle wing 9 has one or more specific "twist" portions between its root and end.

A baffle plate 10 has one end fixed to the side wall of the container 1 and extends substantially horizontally between the paddle wings 9.
As shown in the cross-sectional view of FIG. 2, in the example of the apparatus shown in FIG. 1, the baffle plates 10 are provided in four stages, two per stage, at approximately symmetrical positions with respect to the stirring shaft 8. .

The paddle blade 9, which is shown enlarged in FIG. 3, has one or more "twisted" portions that are spirally twisted between the base and the end of the flat blade material. The "twist" part is the section from the beginning to the end of the "twist" of the wing material, and in that section, the "twist angle θ" of the wing material is
refers to the part where the angle changes up to a predetermined angle. "Twist angle θ" means "twist direction 2" in Figure 6.
1, the wing material 2 at the ``twisting starting point''
2 and the surface of the blade material 22 at the "twisting end point" (hereinafter referred to as "twisting angle", see FIG. 6) is set to 180°. The material of the paddle blade 9 is usually ordinary steel (carbon steel),
Stainless steel is preferable, and the surface of stainless steel is mirror-finished, the surface of common steel is glass-lined, and the surface of common steel or stainless steel is coated with Teflon.

The number of paddle blades used in the present invention, the number of mounting stages, and the twisting angle are not limited to the examples shown in FIGS. 1 to 3. Usually 2 to 4 pieces per tier.
~4 stages can be installed. Additionally, the "twist angle" must be 90° or more. Preferably, the angle is set to 180° or more. If the angle is less than 90°, adhesion of polymer particles to the blade surface, especially the lower surface of the blade, cannot be sufficiently prevented. In the example shown in FIG. 4, the stirring blades 9' have four paddle blades per stage with a twist angle of 360°.

Here, "twist angle 360 degrees" indicates that the angle changed from the starting point of the first "twist" to the end point of the last "twist" is 360 degrees.

Returning to FIG. 1, the baffle plate 10 may be in the form of a plate or the like, but it may have a spirally twisted shape similar to the paddle blades 9, and furthermore, the twist angle may be 180° or more, or A cylindrical shape or the like is preferable because adhesion of polymer particles can be effectively prevented. The number of baffle plates and the number of mounting stages are not limited to the examples shown in Figures 1 to 3, and are usually 1.
Can be installed in 2 to 4 stages with 2 to 4 pieces per stage. Fifth
In the example shown in the figure, four baffle plates 10' are installed per stage approximately symmetrically to the stirring shaft.

The blade diameter d of the paddle blade used in the present invention is preferably d/D≧0.60, more preferably d/D≧0.80, relative to the inner diameter D of the container. When d/D<0.60, adhesion of polymer particles to the inner wall of the container cannot be sufficiently prevented. Also, the wingspan b of the paddle wing is b/d
It is preferable to set it to ≦0.30. When b/d>0.30, the power consumption of the electric motor 6 becomes excessive. Furthermore, it becomes impossible to rotate the stirring blade at high speed in order to uniformly disperse the polymer particles. Furthermore, the distance L between the paddle blades is 0.10≦L/D≦1.0, furthermore, 0.20≦
It is preferable that L/D≦0.50. L/D＜0.10
If L/D>1.0, the suction of the liquid into the paddle blades will be poor, making it difficult to achieve uniform stirring.

The rotation direction of the stirring blade used in the present invention may be either clockwise or counterclockwise, and the rotation speed is preferably determined so that the polymer particles do not settle locally or stay in a suspended state.

In addition, the length of the baffle plate used in the present invention is such that the gap C between the tip and the stirring shaft is C/D≦0.2, and furthermore, C/D≦0.2.
It is preferable to decide so that D≦0.10. C/
When D>0.2, it is not possible to sufficiently prevent the polymer particles from sticking to the stirring shaft. In addition, the gap C′ between the baffle plate and the paddle blade is C′/D≦0.30, and C′/D≦
It is preferable to set it to 0.10. If C'/D>0.30, adhesion of polymer particles to the baffle plate cannot be sufficiently prevented.

Returning to FIG. 1, when the apparatus of the present invention is used for suspension polymerization of ethylene rubber using propylene as a solvent, 11 and 12 are catalyst supply ports, 13 is an ethylene supply port, 14 is a propylene supply port, Reference numeral 15 can be used as a supply port for non-conjugated diene, and 16 can be used as an outlet for EPDM. Reference numeral 17 denotes a hole for guiding propylene out of the reactor when cooling is performed by evaporating propylene. Further, 18 can be used as a hydrogen supply port for controlling the molecular weight.

The materials of the paddle blades and baffle plates used in the present invention are not particularly limited, but are usually made of ordinary steel (carbon steel), stainless steel, etc. Also, stainless steel with a mirror finish or ordinary steel with a surface finished with a mirror finish are used. It is preferable to use a material lined with glass, or a material made of ordinary steel or stainless steel whose surface is coated with Teflon.

Polymers that can be produced by suspension polymerization using the polymerization reaction apparatus of the present invention are either homopolymers or copolymers obtained by copolymerizing two or more different monomers. It may be a combination. Examples of copolymers include ethylene and α- represented by the general formula R-CH=CH ₂ (R is an alkyl group, preferably a linear alkyl group having 1 to 16 carbon atoms). Examples include olefins and rubber-like copolymers comprising these and non-conjugated dienes (hereinafter collectively referred to as ethylene rubber-based rubbers).

In the case of ethylene rubber, typical α-olefins include propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, and 1-octene, with propylene and 1-butene being preferred. In addition, non-conjugated dienes include 5-ethylidene-2-norbornene (ENB), dicyclopentadiene (DCP), 1,4-hexadiene, 5-ethylidene-2-norbornene (ENB), dicyclopentadiene (DCP),
-Propylidene-2-norbornene, 6-methyl-1,5-heptadiene, 1,5-cyclooctadiene, etc., and ENB and DCP are preferred in terms of copolymerization reactivity and physical properties of the vulcanized polymer.

In addition, as a catalyst for copolymerizing these monomers to obtain a polymer, a known Ziegler type catalyst is useful, and a catalyst containing a vanadium compound or a titanium compound and an organoaluminum compound is usually used. be able to. For example, vanadium compounds include vanadium oxytrichloride, vanadium tetrachloride, alcohol (preferably an alcohol having 1 to 12 carbon atoms) modified products thereof, vanadium, triacetylacetonate, oxyvanadium, diacetylacetonate, etc. Examples of titanium compounds include titanium tetrachloride, titanium trichloride, and those supported on carriers such as magnesium chloride and silicon oxide.

As the organic aluminum compound, diethylaluminum chloride, ethylaluminum sesquichloride, ethylaluminum dichloride, triisobutylaluminum, triethylaluminum, and mixtures thereof can be used.

On the other hand, the solvent that can be used in the present invention is preferably one that does not substantially dissolve the polymer, such as
When carrying out slurry polymerization of EPDM, propylene, 1-butene, methylene dichloride, methylene dibromide, ethyl chloride, etc. can be used as a solvent, but as mentioned above, it is preferable to use propylene and 1-butene, which are also monomers. is preferred.

By carrying out suspension polymerization using the polymerization reaction apparatus of the present invention, the following effects can be obtained.

By adding a twist to the paddle wing, it is possible to eliminate the adhesion of polymer to the back side of the paddle wing. This is because by adding a twist, the vortex generated on the back side of the paddle blade can be substantially eliminated. This effect can be similarly obtained when the baffle plate is twisted or made into a cylindrical shape.

By providing the paddle blades in multiple stages and the baffle plates in multiple stages between the paddle blades, there is no dead space stagnation in any part of the reaction solution. It eliminates adhesion to the blades and allows for uniform and stable reactions.

The interaction between the multi-stage paddle blades and the multi-stage baffle plate provides a strong shearing effect on the reaction liquid at any part of the reaction liquid, making it possible to finely disperse the catalyst and, therefore, to form the resulting polymer into fine particles. can be dispersed into This makes it possible to carry out a uniform polymerization reaction, and also facilitates handling such as transfer of the slurry liquid.

Since it is a relatively simple device, it is extremely versatile for suspension polymerization.

The present invention will be explained in more detail with reference to specific examples below, but the embodiments of the present invention are not limited thereto.

Example 1 Using the reactor shown in FIG. 1, suspension polymerization of ethylene, propylene, and ENB was carried out in liquid propyne. The dimensions of the main parts of the reactor were as follows. The inner diameter D of the cylindrical part of the reaction vessel is 200 mm, the length from the top lid to the bottom of the reaction vessel is 430 mm, the diameter of the stirring shaft is 20 mm, the paddle blade is twisted 180°, and the blade diameter d is
A four-stage two-paddle blade with a blade width b of 160 mm and a blade width b of 20 mm was used at a rotation speed of 200 rpm. The distance L between the paddle blades was 70 mm.

The baffle plate had a cylindrical shape with an outer diameter of 15 mm, and the gap C between its tip and the stirring shaft was 17.5 mm, and the gap C between the baffle plate and the paddle blade was 15 mm.

During the reaction, the amount of liquid in the reactor was kept at about 10%.

Next, the polymerization reaction operation will be explained.

In Figure 1, propylene is in liquid form from pipe 14 at a polymerization pressure of 5 kg/H, and ethylene is polymerized from pipe 13 at a polymerization pressure of 14.0.
Kg/cm ² G was supplied. Also tubes 11,1
Diethyl aluminum chloride from 2 respectively
120 mmol/hr of basium oxytrichloride/hr and 5-ethylidene-2-
Norbornene (ENB) at 140gr/H, and tube 1
Hydrogen was supplied from tube 8 at a molar ratio of 1/20 to that of ethylene, and the polymer slurry was continuously discharged from tube 16 into a tank to carry out continuous suspension polymerization at a reaction temperature of 20.degree.

The polymer concentration at steady state was 31% by weight, and the polymer particles were in the form of granules of 0.5-2 mm.

The produced polymer has a Mooney viscosity (ML ₁₊₄ , 100
°C) was 66, the propylene content was 41% by weight, and the ENB content was 15.2 in terms of iodine number.

90 hours after the start of the polymerization reaction, the supply of catalyst, ethylene, ENB, and hydrogen was stopped, and then about 3
Only propylene is supplied for an hour, and then the entire contents of the reactor are discharged into a slurry extraction tank.
After stopping stirring and purging with nitrogen, the top cover was removed and the inside of the reactor was observed.
No polymer adhesion was observed on the baffle plate.

Example 2 The paddle blade is twisted at an angle as shown in Figure 4.
360°, the number of plates was 4 per stage, the shape of the baffle plate was a 15 mm wide flat plate twisted by 180°, and the reactor had the same shape, dimensions, and specifications as in Example 1. Using ethylene and propylene and ENB
The suspension polymerization of was carried out in liquid propylene. The reaction conditions such as the stirring rotation speed, the amount of liquid in the reactor, and the supply of propylene, diethylaluminum chloride, vanadium oxytrichloride, ENB, hydrogen, and ethylene were the same as in Example 1.

The polymerization reaction was carried out at 20° C. and 14.0 Kg/cm ² G under continuous operation as in Example 1.

At steady state, the concentration of the polymer was 33% by weight, and the polymer particles were in the form of granules of 0.5-2 mm.

The produced polymer has a Mooney viscosity (ML ₁₊₄ , 100
℃) was 75, the propylene content was 38% by weight, and the ENB content was 14.7 in terms of iodine number.

90 hours after the start of the polymerization reaction, Example 1
In the same manner as above, the slurry was extracted, and after the atmosphere was replaced with nitrogen, the inside of the reactor was observed, and no polymer was observed to be attached to the inner wall of the reaction vessel, the stirring blade, or the baffle plate.

Comparative example 1 Width without twisting the paddle blade: 20mm, 2 per stage
Flat paddle blade with 4 stages (flat paddle blade)
Using a reactor having the same shape, dimensions, and specifications as in Example 1, suspension polymerization of ethylene, propylene, and ENB was carried out in liquid propylene under the same reaction conditions as in Examples 1 and 2.

The polymer concentration at steady state was 29% by weight, and the polymer particles were in the form of granules of 0.5-2 mm. In addition, the produced polymer, which included some with a diameter of 4 mm, had a Mooney viscosity (ML ₁₊₄ , 100°C) of 70, a propylene content of 44% by weight, and an ENB content of 15.0 in terms of iodine value. .

90 hours after the start of the polymerization reaction, Example 1
After replacing the slurry with nitrogen in the same manner as above, we observed the inside of the reactor and found that no polymer was observed on the inner wall or baffle plate of the reaction vessel, but there was no polymer attached to the paddle impeller, which is the stirring blade. It was found that the polymer was adhered to the backside of the blades in the form of enlarged lumps, and it was determined that continuous operation was impossible.

Comparative Example 2 The paddle blades are flat, non-twisting, with a width of 20 mm, 2 blades per stage, and 4 stages, and are inclined at 45° (slanted paddle blades), and the baffle plate is a flat plate. The gap between its tip and the stirring shaft is 20
Suspension polymerization of ethylene, propylene, and ENB was carried out under the same reaction conditions as in Example 1 using a reactor having the same shape, dimensions, and specifications as in Example 1 except that the plate width was 15 mm.

The direction in which the paddle blades were tilted was the direction in which the polymer particles were lifted up by the rotation of the paddle blades.

The polymer concentration at steady state was 30% by weight, and the polymer particles were in the form of granules of 0.5-2.0 mm. Approximately 4 in some parts
Including those with a large mm diameter. The polymer produced by the polymerization reaction has a Mooney viscosity (ML ₁₊₄ , 100℃).
78, the propylene content was 38% by weight, and the ENB content was 14.8 in terms of iodine number.

Approximately 70 hours after the start of the polymerization reaction, the current value of the electric motor for driving the stirring blades sometimes showed abnormally large values, so the polymer slurry was immediately extracted in the same manner as in Example 1 and replaced with nitrogen gas. After replacing with
When the reactor was opened and the inside of the reactor was observed, there was little polymer adhesion to the inner wall of the reaction vessel, but there was a lot of polymer adhesion to the paddle blades and baffle plates, and large lumps were observed especially on the back side of the blades and the baffle plate. was generated, and the polymer adhering to the paddle blade was in contact with the polymer adhering to the baffle plate in some places.

The reason why the current became so abnormally large that stirring became impossible was because the adhered polymers came into contact with each other in this way.

Comparative Example 3 The number of paddle blades was 2 per stage, the twist angle was 360°, and the baffle plates were 4 flat plates with a length of 220 mm and a width of 10 mm, extending from the bottom of the reactor toward the top lid. , which were fixed to the inner wall of the reactor at equal intervals parallel to the stirring shaft.

A gap of 5 mm was provided between the baffle plate and the reaction vessel, and the baffle plate was installed so that the entire baffle plate was immersed in the liquid. Suspension polymerization of ethylene, propylene, and ENB was carried out under the same reaction conditions as in Example 1 using a reactor in which all other conditions were the same as in Example 1.

The polymer concentration in the steady state was 28% by weight, and most of the polymer particles were in the form of granules with a diameter of 0.5 to 2.0 mm, but some with a diameter of approximately 5 mm were included.

The polymer produced by the polymerization reaction has a Mooney viscosity (ML ₁₊₄ , 100℃) of 66 and a propylene content of 40.
The weight percent and ENB content was 16.1 in terms of iodine value.

About 10 hours after the start of the polymerization reaction, the current value began to show an abnormally large value as in Comparative Example 2, so the polymer slurry was immediately extracted as in Comparative Example 2 and replaced with nitrogen. When the reactor was opened and the inside of the reactor was observed, the polymer was found to be heavily adhered to the entire inside.

In particular, the polymer adhered in large clumps to the area where the baffle plate was attached and the inner wall of the reaction vessel in the vicinity.

Further, the adhesion to the stirring shaft between the paddle blades was extremely severe.

Incidentally, the amount of adhesion to the paddle blade itself was relatively small compared to the amount of adhesion to the stirring shaft.

Comparative Example 4 Suspension polymerization of ethylene, propylene, and ENB was carried out under the same reaction conditions as in Example 1 using an anchor-type stirring blade and a reactor without baffles.

The width of the anchor blade used at this time was 20 mm, the blade diameter was 160 mm, the number of blades was 2, and the length from the lower end of the curved bottom to the tip of the blade was 200 mm.

Further, this anchor blade was attached so that the entire anchor blade was immersed in the liquid. All other conditions of the reactor were the same as in Example 1.

When a polymerization reaction was carried out using this reactor, about 6 hours after the start of the reaction, it became impossible to smoothly discharge the polymer particles, so Comparative Example 2,
As in step 3, immediately remove the polymer slurry,
After purging with nitrogen, the reactor was opened and the inside of the reactor was observed, and it was found that the polymer was extremely attached to the stirring shaft.
A very large lump with a diameter of about 100 to 150 mm was attached near the bottom of the reaction vessel.

Moreover, most of the small amount of polymer particles remaining inside the reactor were large particles with a diameter of 5 to 10 mm.

The reason why it became impossible to extract the polymer slurry was due to large lumps adhering to the stirring shaft and because the diameter of the polymer particles themselves increased.

[Brief explanation of drawings]

FIG. 1 is a partial vertical cross-sectional view of one configuration example of the apparatus of the present invention, and FIGS. 2 and 3 are a cross-sectional view and a partially enlarged view of the apparatus. FIGS. 4 and 5 are partially enlarged views and cross-sectional views showing other configuration examples of the apparatus of the present invention. FIG. 6 is a diagram specifically showing the twist angle of the paddle blade. DESCRIPTION OF SYMBOLS 1... Reaction container, 2... Top lid, 5... Jacket, 6... Electric motor, 8... Stirring shaft, 9, 9'...
Paddle wing, 10, 10'... baffle plate.

Claims (1)

[Claims] 1. A polymerization reaction apparatus comprising a stirring blade with paddle blades arranged in multiple stages in a cylindrical container and a baffle plate positioned in multiple stages between the paddle blades, wherein the paddle blades have a twist angle (θ) of 90° or more. A polymerization reaction device characterized by having one or more twisted portions.