JP2001179069A - Stirring apparatus, coagulation separation method of polymer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a stirring apparatus which has scarce probability of causing adhesion of crumb as a scale in the inside or causing the clogging of a pipeline by blocking when a polymer is coagulated and/or separated from a polymer solution obtained by solution polymerization. SOLUTION: The stirring apparatus 2 is an apparatus having stirring blades 6 installed in the inside of a stirring tank 4 in a freely rotatable manner and attached to a stirring rotation shaft 8 and so composed as to have the ratio (H/D) within 0.25-0.45, wherein H denotes the depth from the liquid surface to the upper end of a stirring blade 6 in the uppermost step and D denotes the inner diameter of the stirring tank 4. It is preferable that the ratio (h/D) of the engulfed depth (h) of the liquid to the inner diameter (D) of the stirring tank 4 is higher than 1/3. It is also preferable that the ratio (d/D) of the maximum outer diameter (d) of the stirring blades 6 to the inner diameter (D) of the stirring tank 4 is 0.55-0.75.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a stirrer which can be suitably used for coagulating or separating (stripping) a polymer from a polymer solution obtained by solution polymerization, and The present invention relates to a method for coagulating and separating a polymer obtained by solution polymerization using the same.

[0002]

2. Description of the Related Art For example, when coagulating and / or separating (stripping) a polymer from a polymer solution obtained by a solution polymerization in which a polymerization reaction is carried out in a solvent in which a monomer is soluble, a conventional method has been employed. A stirring device with wings is used. As a stirring blade used in this type of stirring device, for example, a blade using a multi-stage bull margin blade or a blade combining this with a tilted paddle blade is known.

[0003]

However, in the case of using a stirrer having a multi-stage blue-margin blade to coagulate and separate a polymer, particularly in a rubber-based polymer solution, poor mixing between top and bottom is inferior. Because the polymer (crum) that is coagulated and separated has a lower specific gravity than the solvent, it floats near the liquid surface and adheres as scale to the inner wall of the stirring tank, or blocks the piping due to blocking. Sometimes clogged. For this reason, there was a problem that the stirring device was once stopped and the inside of the stirring tank was periodically maintained, and the productivity was reduced.

[0004] It is an object of the present invention to provide a method for coagulating and / or separating a polymer from a polymer solution obtained by solution polymerization, in which crumb adheres as a scale to the inside,
An object of the present invention is to provide a stirrer that is less likely to cause blockage of a pipe due to blocking, and a method of coagulating and separating a polymer using the stirrer.

[0005]

Means for Solving the Problems The present inventors focused on the relationship between the size of the stirring tank and the position and size of the stirring blade, and designated a specific stirring blade arranged at a specific position to a specific size. It has been found that the above object can be achieved by using the composition in a stirring tank.

That is, the stirring device according to the present invention is a stirring device which is rotatably mounted inside a stirring tank and has a stirring blade mounted on a stirring rotating shaft, wherein a liquid with respect to an inner diameter (D) of the stirring tank is provided. The ratio (H / D) of the depth (H) from the surface to the upper end of the uppermost stirring blade is set to 0.25 to 0.45.

[0007] Preferably, the ratio (h / D) of the liquid entrainment depth (h) to the inner diameter (D) of the stirring tank is greater than 1/3.

Preferably, the ratio (d / D) of the maximum outer diameter (d) of the stirring blade to the inner diameter (D) of the stirring tank is 0.1.
55 to 0.75.

[0009] Preferably, in the present invention, the stirring blade is mounted on a bottom of a stirring rotation shaft, and a first blade is mounted above the stirring rotation shaft. At least a second wing mounted in parallel and at a predetermined interval, and mounted at the predetermined depth (H) from the liquid level.

[0010] Preferably, the ratio (d1 / D) of the outer diameter (d1) of the first blade to the inner diameter (D) of the stirring tank is 0.35 to 0.35.
0.55.

Preferably, the ratio (d3 / D) of the outer diameter (d3) of the second blade to the inner diameter (D) of the stirring tank is 0.55 to 0.55.
0.75.

The method for coagulating a polymer according to the present invention is characterized in that the polymer is coagulated by stirring using the above-mentioned stirring device and, if necessary, blowing steam.

The method of separating a polymer according to the present invention is characterized in that the polymer is separated by stirring and, if necessary, by blowing steam using the above-mentioned stirring device.

The type of the stirring blade is, for example,
Included are inclined paddle blades, full zone blades, and max blend blades, and preferably paddle blades.

[0015]

In the stirring apparatus according to the present invention, the ratio (H / D) of the depth (H) from the liquid surface to the upper end of the uppermost stirring blade with respect to the inner diameter (D) of the stirring tank is set to 0.25 to 0.45. As a result, crumbs floating near the liquid surface can be effectively submerged and scale can be prevented from adhering to the inner wall of the stirring tank. Further, the ratio (h / D) of the liquid entrainment depth (h) to the inner diameter (D) of the stirring tank is made larger than 1/3 ((1/3) <(h / D)), whereby the stirring is performed. Adhesion of crumbs to the inner wall of the tank and blocking due to mutual adhesion of crumbs can be effectively prevented.

The ratio (d / D) of the outer diameter (d) of the stirring blade to the inner diameter (D) of the stirring tank is set in a specific range (0.55 to 0.55).
By setting the ratio to 0.75), the above-described effects become more remarkable.

The stirring device according to the present invention is preferably used as a coagulation device and / or a separation device used for coagulating and / or separating a polymer in a polymer solution obtained by solution polymerization. it can. The stirring power consumption (Pv) per unit volume of the solution is usually 0.2
Ｋ3 kw / m ³ .

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a stirring device according to the present invention
Description will be made based on the embodiment shown in the drawings. FIG. 1 is a diagram showing an outline of a polymer production process using a stirrer according to one embodiment of the present invention, FIG. 2 is a cross-sectional view of a main part showing a stirrer according to one embodiment of the present invention, and FIG. FIG. 3 is a diagram illustrating the operation of the stirring device of FIG. 2.

In this embodiment, after describing the outline of the polymer production system, the configuration and operation of the stirring device according to one embodiment of the present invention will be described.

[0020] As shown in the polymer manufacturing system example 1, polymer production system 3 according to the present embodiment is a system for producing a synthetic rubber by solution polymerization, the polymerization vessel 31, a tank 32, solidification Tank 33, stripping tank 34, tank 3
And 5.

The polymerization vessel 31 is a tank for polymerizing monomers by solution polymerization to produce a polymer, and is connected to a tank 32 described later by a polymer solution supply line 321. In the present embodiment, an autoclave type having a cooling system and a stirring system is used as the polymerization can 31. Suitable monomers for the present invention include conjugated dienes such as butadiene and isoprene, or a mixture of the conjugated diene and an aromatic vinyl monomer represented by styrene and the like. The polymer applicable to the present invention is not particularly limited, but is preferably a conjugated diene (co) polymer or an aromatic vinyl-conjugated diene copolymer, and more preferably S-polymer by a solution polymerization method.
BR (styrene-butadiene rubber).

The tank 32 adds a polymerization terminator and an antioxidant to the polymer solution supplied from the polymerization can 31 after the completion of the polymerization reaction to prevent fluctuations in Mooney viscosity and polymerization rate. And a tank for adjusting the polymer solution to a predetermined polymerization rate and Mooney viscosity, and is connected to a coagulation tank 33 described later by a supply line 331.

The coagulation tank 33 removes unreacted monomers and solvents from the polymer solution supplied from the tank 32,
This is a tank for obtaining a hot water slurry of synthetic rubber solidified as a crumb. The tank is connected to a stripping tank 34 described later by a hot water slurry supply line 341, and is connected to the tank 35 by a solvent recovery line 351. The recovered unreacted monomer is recovered through a residual monomer recovery line (not shown) and can be reused.

The stripping tank 34 is a tank for sufficiently removing unreacted monomers and solvents from the synthetic rubber hot water slurry supplied from the coagulation tank 33 to obtain a rubber crumb slurry. The crumb slurry is sent through a crumb slurry supply line 342 to a drying step. Stripping tank 34
Is connected to a tank 35 described later via a solvent recovery line 351.
Connected to. The stripping tank 34 is composed of the stirring device 2 (see FIG. 2) according to the present embodiment, but details will be described later.

The tank 35 is a tank for storing the solvent recovered from the coagulation tank 33 and the stripping tank 34, and is recovered through a recovery line 352 and reused. Coagulation or separation (stripping) of polymer
Can be performed by a known method, but a method in which steam is blown is particularly preferable.

The stirrer will be described the configuration of the stirring device 2 according to the present embodiment.

As shown in FIG. 2, the stirring device 2 according to the present embodiment has a stirring tank 4 and stirring blades 6. A stirring port 4 for adjusting the liquid level is provided in the stirring tank 4.
Is formed.

On the inner wall of the stirring tank 4, a baffle plate 14 (which may be in the form of a rod) is mounted substantially parallel to a rotating shaft 8 to be described later. In the present embodiment, the two baffle plates 14 are mounted at 180-degree symmetric positions, but may be single or three at the substantially equal or irregular intervals along the inner circumference of the stirring tank 4.
You may attach more than one. The baffle plate 14 is provided on the inner wall of the stirring tank 4 so as not to contact the rotating stirring blade 6. The inner wall of the stirring tank 4 and the baffle plate 14 may be subjected to surface processing such as Teflon coating or glass lining. The inner diameter D of the stirring tank 4 is preferably 500 to 50.
00 mm. The stirring tank 4 is made of, for example, metal.

The stirring blade 6 is mounted on a stirring rotating shaft 8, and the rotating shaft 8 is driven to rotate by a motor 10. The rotating shaft 8 is made of, for example, metal. In the embodiment shown in FIG. 1, the motor 10 is mounted on the upper part of the stirring tank 4, but may be mounted below the stirring tank 4.

In this embodiment, the stirring blade 6 is symmetrical with respect to the rotation axis 8 and has a first inclined paddle blade 62, a bull margin blade 64, and a second inclined paddle blade 66. ,
By rotating the rotation shaft 8, the liquid in the stirring tank 4 can be stirred and mixed.

The maximum outer diameter d of the stirring blade 6 (d in this embodiment, d
3) is preferably 275 to 3750 mm, and the maximum outer diameter d of the stirring blade 6 with respect to the inner diameter D of the stirring tank 4.
Is preferably 0.55 to 0.75, more preferably 0.6 to 0.7, and still more preferably 0.6 to 0.7.
1 to 0.66. In addition, the ratio W / D of the maximum blade width W of the stirring blade 6 to the inner diameter D of the stirring tank 4 is preferably set to 0.1.
03 to 0.18.

The first inclined paddle blade 62 has a stirring rotation shaft 8.
The wing surface is 10 to the vertical direction.
The blades are arranged at an inclination of about 60 °, and at the axial position, four blades are arranged at 90 ° intervals in the circumferential direction. However, the number of blades in the circumferential direction is not particularly limited. The outer diameter d1 of the first inclined paddle wing portion 62 is preferably 175 to 2750 m.
m, and the ratio d1 / D of the outer diameter d1 of the first inclined paddle wing portion 62 to the inner diameter D of the stirring tank 4 is not particularly limited, but is preferably 0.35 to 0.55, more preferably 0.4 -0.5, more preferably around 0.44. The width W1 of the first inclined paddle wing portion 62 is preferably 1
5 to 900 mm, the first with respect to the inner diameter D of the stirring tank 4.
The ratio W1 / D of the width W1 of the inclined paddle wing portion 62 is preferably 0.03 to 0.18.

The bulging margin wings 64 are mounted on the stirring rotation shaft 8 at a predetermined interval L1 from the first inclined paddle wings 62, and three wings are arranged at intervals of 120 ° in the circumferential direction. The number of blades in the circumferential direction is not particularly limited. The outer diameter d2 of the bull margin wing 64 is preferably 175 to 275.
0 mm, and the ratio d2 / D of the outer diameter d2 of the bulging margin portion 64 to the inner diameter D of the stirring tank 4 is preferably 0.3.
It is 5 to 0.55, more preferably 0.4 to 0.5, and still more preferably about 0.44. Bull Margin Wing 64
(A flat plate 642 formed at the tip of the wing in this embodiment)
) W2 is preferably 25 to 750 mm, and the width W2 of the bulging margin wing portion 64 with respect to the inner diameter D of the stirring tank 4.
Is preferably 0.05 to 0.15. The distance L1 between the first inclined paddle wing part 62 and the bull margin wing part 64 is preferably 130 to 1300 mm.
It is.

The second inclined paddle wing portion 66 is spaced a predetermined distance L2 from the bull margin wing portion 64, and is located at a position closest to the liquid level as compared with the first inclined paddle wing portion 62 and the bull margin wing portion 64. It is mounted on the stirring rotation shaft 8. Second
In the present embodiment, the inclined paddle wings 66 are arranged such that the wing surface is inclined at about 10 to 60 ° with respect to the vertical direction, and four wings are arranged at 90 ° circumferential intervals at the axial position. However, the number of blades in the circumferential direction is not particularly limited.
The outer diameter d3 of the second inclined paddle blade section 66 (corresponding to the maximum outer diameter d of the stirring blade 6 in the present embodiment) is preferably 275.
2750 with respect to the inner diameter D of the stirring tank 4.
The ratio d3 / D of the outer diameter d3 of the inclined paddle wing portion 66 is preferably 0.55 to 0.75, more preferably 0.6 to 0.5.
7, more preferably around 0.63. The width W3 (corresponding to the maximum blade width W of the stirring blade 6 in the present embodiment) of the second inclined paddle blade 66 is preferably 15 to 900 mm.
The ratio W3 / D of the width W3 of the second inclined paddle blade portion 66 to the inner diameter D of the stirring tank 4 is preferably 0.03 to
0.18. The distance L2 between the second inclined paddle wing portion 66 and the bull margin wing portion 64 is preferably 130 to
1300 mm.

The depth H from the liquid level to the second inclined paddle blade 66 is preferably 125 to 2250 mm, and the second inclined paddle blade (the uppermost stirring blade) with respect to the inner diameter D of the stirring tank 4. In this embodiment, the ratio H / D of the depth H to the upper end of 66 is 0.25 to 0.45, preferably 0.38 to 0.42.

The stirring blade 6 is made of, for example, metal or the like, and may be subjected to a surface processing such as Teflon coating or glass lining if necessary.

The stirring blade 6 of the present invention can be arbitrarily installed according to the shape of the stirring tank 4 (such as a vertical tank).

As shown in FIG. 1, the polymer solution after the completion of the polymerization reaction is supplied from a polymerization vessel 31 to a tank 32 through a line 321. The polymer solution thus obtained is supplied to the coagulation tank 33 through the line 331,
Here, the rubber is sucked into heated water heated by steam to have a temperature equal to or higher than the boiling point of the solvent, and unreacted monomers and the solvent are evaporated and removed. 12m
m, more preferably 5-10 mm)
Dispersed in warm water to obtain a warm water slurry.

The obtained hot water slurry is supplied to a stripping tank 34 through a line 341 and the residual monomer and the residual solvent are sufficiently stripped by steam to obtain a rubber crumb slurry. In addition,
The temperature and pressure conditions for stripping vary depending on the type of solvent, but usually the principle of steam distillation is used.

In this embodiment, the stripping tank 3
The stirring device 2 shown in FIG. In the stirring device 2, the height H1 from the inner bottom surface of the stirring tank 4 to the liquid surface (see FIG. 2) is preferably 540 to 54.
00 mm. In the stirring device 2, when the motor 10 is operated after the hot water slurry is charged, the rotating shaft 8 starts rotating and the stirring blade 6 also rotates. The number of rotations of the rotating shaft 8 is determined as appropriate depending on the viscosity and concentration of the polymer solution, but is preferably about 30 to about 200 rpm. If the number of rotations is too low, polymer particles (crums) may adhere to the inner wall surface of the stirring tank 4 as scales, or the crumbs may adhere to each other to cause blocking. When the stirring blade 8 rotates, the hot water slurry in a solid-liquid state is loosened and broken, and a rubber crumb having a specific gravity lighter than that of the solvent tends to float near the liquid surface.

Here, in the stirring device 2 according to the present embodiment, the stirring blade 6 (the third
Inclined paddle wing 62) By setting the ratio H / D of the depth H to the upper end to be 0.25 to 0.45, crumbs floating near the liquid surface can be effectively sunk. In addition, the crumbs are effectively prevented from adhering to the inner wall of the stirring tank 4 as a scale and blocking due to mutual adhesion of the crumbs. Further, in the present embodiment, by increasing the entrainment depth h (see FIG. 3) of the warm water slurry at the time of stirring, specifically, the ratio h / D of the entrainment depth h to the inner diameter D of the stirring tank 4 is reduced to 1 / By making it larger than 3, it is possible to more effectively prevent the adhesion of crumbs to the inner wall of the stirring tank and the blocking due to mutual adhesion of crumbs. Further, in the present embodiment, the ratio d / D of the maximum outer diameter d (d3) of the stirring blade 6 to the inner diameter D of the stirring tank 4 is 0.55.
And the ratio W / D of the maximum blade width W (W3) of the stirring blade 6 to the inner diameter D of the stirring tank 4 is 0.03 to 0.75.
By setting the ratio to 0.18, the above-described effects become more remarkable.

The resulting crumb slurry is fed to line 342
After passing through to the drying process, the dewatered rubber is again put into a dryer with heated air by an air conveyor as a small crumb in a crusher, dried, weighed and molded,
The product is packaged.

Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments at all, and can be implemented in various modes without departing from the gist of the present invention. Of course.

For example, in the above embodiment, the stirring device 2 of the present invention is used as the stripping tank 34, but may be used as the coagulation tank 33.

[0045]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples. In the examples, parts and percentages indicating percentages are based on weight.

Example 1 A stirring device 2 shown in FIG. 2 was used. As the stirring tank 4, a stainless steel stirring tank having an inner diameter D of 260 mm was used. As the stirring blade 6, a first inclined paddle blade portion 62
(Outer diameter d1 = 115 mm, blade width W1 = 13 mm, (d
1 / D) = 0.44, (W1 / D) = 0.05, the wing surface is inclined at approximately 45 ° with respect to the vertical direction, and the number of wings is 4 at 90 ° intervals.
Sheet. ) And the distance L1 between the first inclined paddle wing portion 62 is 67.
mm bull margin wings 64 (outer diameter d2 = 115 m
m, blade width W2 = 24 mm, (d2 / D) = 0.44,
(W2 / D) = 0.09) and a second inclined paddle wing 66 having an interval L2 of 67 mm between the bulge margin wing 64 and the second margin paddle wing 66.
(Outer diameter d3 = 164 mm, blade width W3 = 19 mm, (d
(3 / D) = 0.63, (W3 / D) = 0.07, the blade surface is inclined at approximately 45 ° with respect to the vertical direction, and the number of blades is 4 at 90 ° intervals.
Sheet. ) Was used (see FIG. 2).

Into the stirring tank 4 of the stirring device 2, 92 parts of a hot water slurry containing 8 parts of crumb of styrene-butadiene rubber (SBR) obtained by solution polymerization of styrene and butadiene were charged. Average crumb diameter of crumb is about 10m
m. Height H1 from inner bottom to liquid level of stirring tank 4
Was 280 mm, and the depth H from the liquid surface to the upper end of the second inclined paddle blade section (uppermost stirring blade) 66 was 102 mm. Therefore, the relationship between the inner diameter D and the depth H is (H /
D) = 0.39. Next, the motor 10 was operated to rotate the stirring blade 6 at a rotational speed of about 214 rpm. The stirring power Pv of the stirring blade 6 was 0.4 kw / m ³ .
As the stirring power Pv, the power of the no-load operation at the same rotation speed was previously subtracted from the measured value to obtain the stirring power. After the start of stirring, 2
After a second, the entrainment of the liquid occurs as shown in FIG. 3, and the entrapment depth h of the liquid with respect to the inner diameter D of the stirring tank 4 is:
(1/3) was exceeded. Steam was blown in this stirring state, and after 72 hours, steam blowing and stirring were stopped, and the state of scale adhesion and blocking in the stirring tank 4 and the stirring blade 6 was visually evaluated. As a result, there was almost no adhesion of scale and no blocking occurred.

The crumb diameter is a value obtained by measuring each particle diameter of 50 particles visually and expressing the number average particle diameter. The viscosity of the solvent after removing the crumb of the crumb slurry is 1c
p.

COMPARATIVE EXAMPLE 1 The first inclined paddle blades 62 and the three bulging margin blades 64 from the bottom to the top of the stirring rotary shaft 8 without using the second inclined paddle blades 66 as the stirring blades 6. Were formed at the same intervals as in Example 1, except that they were formed at predetermined intervals. Note that the first inclined paddle wing portion 62,
The distance between each of the first bull margin wing 64 and the second bull margin wing 64 is 43 m.
m, and the distance between the second bull margin wing 64 and the third bull margin 64 was 48 mm.

Then, the same hot water slurry as in Example 1 was charged into the stirring tank 4. The height H1 from the inner bottom surface to the liquid surface of the stirring tank 4 is 280 mm, and the depth H from the liquid surface to the position where the third bulmar margin wing portion (topmost stirring blade) 64 is mounted is 53 mm. there were. Therefore, the relationship between the inner diameter D and the depth H was (H / D) = 0.20. Next, the motor 10 is operated to rotate the stirring blade 6 at a rotational speed of about 198.
Rotated at rpm. The stirring power Pv of the stirring blade 6 is 0.4
kw / m ³ . Even after 10 minutes from the start of the stirring, the entrainment of the liquid is small, and then the stirring is continued as it is. After 72 hours, the stirring is stopped, and the scale adheres to the stirring tank 4 and the stirring blade 6. Was visually evaluated. As a result, blocking of highly adhesive crumb and adhesion of scale were confirmed on the upper part of the inner wall of the stirring tank 4. Thereby, the superiority of Example 1 was confirmed.

[0051]

As described above, according to the present invention, when a polymer is coagulated and / or separated from a polymer solution obtained by solution polymerization, crumbs adhere to the inside as scales, It is possible to provide a stirrer that is less likely to cause blockage of a pipe due to blocking, and a method of coagulating and separating a polymer using the stirrer.

[Brief description of the drawings]

FIG. 1 is a diagram showing an outline of a polymer production process using a stirrer according to one embodiment of the present invention.

FIG. 2 is a sectional view of a main part showing a stirring device according to one embodiment of the present invention.

FIG. 3 is a view for explaining the operation of the stirring device of FIG. 2;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 2 ... Stirrer 4 ... Stirring tank 6 ... Stirrer blade 62 ... 1st inclined paddle wing part 64 ... Bull margin wing part 66 ... 2nd inclined paddle wing part 8 ... Stirring rotating shaft 10 ... Motor 14 ... Baffle plate 3 ... Polymer Production system 31 Polymerization can 32 Tank 321 Polymer solution supply line 33 Coagulation tank 331 Supply line 34 Stripping tank (= stirrer 2) 341 Hot water slurry supply line 342 Crumb slurry supply line 35 Tank 351 ... Solvent recovery line 352 ... Recovery line

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Hiroshi Yagi 1-2-1, Yakko, Kawasaki-ku, Kawasaki-shi, Kanagawa F-term in the Zeon Corporation General Development Center 4G078 AA13 AB11 BA05 BA09 CA01 CA08 CA12 CA17 DA01 DB01 DC10 EA20 4J011 AB09 DA04 DB19 DB30 DB34 4J100 AB02P AS02Q CA04 GC16

Claims (5)

[Claims] 1. A stirring device rotatably mounted inside a stirring tank and having a stirring blade mounted on a stirring rotation shaft, wherein an upper end of the uppermost stirring blade from a liquid level with respect to an inner diameter (D) of the stirring tank. The ratio (H / D) of the depth (H) to 0.25 to 0.4
A stirrer as 5. 2. The stirrer according to claim 1, wherein a ratio (h / D) of a liquid entrainment depth (h) to an inner diameter (D) of the stirrer is larger than １ ／. 3. The ratio (d / D) of the maximum outer diameter (d) of the stirring blade to the inner diameter (D) of the stirring tank is 0.55 to 0.5.
The stirring device according to claim 1, wherein the stirring device is 75. 4. A method for coagulating a polymer, comprising coagulating the polymer using the stirring device according to claim 1. 5. A method for separating a polymer, comprising using the stirring device according to claim 1 to separate the polymer.