JP4067240B2 - Method and apparatus for concentrating polymer solution - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for concentrating and removing volatile components from a polymer solution.
[0002]
[Prior art]
Conventionally, polymerization methods such as bulk polymerization, suspension polymerization, emulsion polymerization, and solution polymerization have been used to obtain polymers. In general, styrenic resins are produced by a bulk continuous polymerization method or a solution continuous polymerization method. In these methods, byproducts such as monomers or dimers and / or a solvent are contained at the end of the polymerization. In addition, in the case of batch-type solution polymerization, the polymer solution often contains a large amount of volatile substances such as monomers, dimers and other by-products and solvents. Therefore, in order to finally obtain the target polymer by these polymerization methods, there is a problem that the polymer solution must be further purified.
[0003]
And a method of separating and recovering or removing volatile substances from the polymer solution containing volatile components such as solvents and monomers, that is, as a devolatilization step, a method by steam stripping, a method by devolatilization extruder, A method of flash concentrating after preheating, a method of performing devolatilization by dividing flash concentration into two or three steps, a method of further devolatilizing with a devolatilizing extruder after flash concentration, and the like are used.
[0004]
Among these methods, steam stripping has a problem in that a large amount of steam is used and a drying step is required thereafter, which requires a running cost. The method of devolatilizing a polymer solution obtained by polymerization directly with a devolatilizing extruder requires devolatilizing a large amount of monomer and solvent, and therefore requires a large devolatilizing extruder. There is a problem that the apparatus becomes expensive.
In contrast, the devolatilization method using flash concentration and the method of devolatilizing with a devolatilization extruder after flash concentration often require low running costs and equipment costs, and the process is relatively simple. Adopted by various processes.
[0005]
However, the devolatilization method using flash concentration also has some problems and various technical improvements have been made. For example, at the time of flash concentration, the polymer solution after flashing increases in viscosity in the flash drum and foams. As a result, when devolatilization exceeds a certain level, it will not proceed or the polymer will be scattered and attached to the inner wall of the flash drum. In addition, even before flashing, when a sufficient amount of heat is applied to the polymer solution for flashing, there is a problem that if the heating time is prolonged, the polymer is thermally deteriorated.
[0006]
There have been several technical improvements to these issues. For example, regarding the inhibition of devolatilization accompanying the increase in the viscosity of the polymer solution after flashing, as shown in Japanese Patent Publication No. 45-31678, a heating element is installed in the flash drum, and the flashed polymer In some cases, as described in Japanese Patent Publication No. 47-28691, the flash is divided into two stages, and a blowing agent is added before the second stage flash to promote devolatilization.
[0007]
Japanese Patent Application Laid-Open No. 55-56103 deals with thermal degradation of the polymer during preheating by using an instantaneous heater.
[0008]
As noted above, various technical improvements have been made to flash concentration. However, it is not yet satisfactory, and in particular, no attention has been paid to the temperature control of the wall surface of the flash drum in the flash concentration using a flash drum that is generally used.
[0009]
Conventionally, a flash drum is only provided with one jacket for adjusting the temperature of the wall surface. When performing flash concentration using a flash drum, a pump for extracting the flashed polymer is installed at the lower part of the flash drum. At that time, in order to prevent the intermittent operation of the pump, the flashed polymer is operated while being retained in an appropriate amount below the flash drum. If the extraction is not stable, stable operation is difficult in the subsequent processes. When operating such a flash drum, if the wall surface temperature of the flash drum is too low, the evaporated solvent will condense and reflux on the wall surface of the flash drum, reducing the concentration efficiency or making the extraction unstable due to concentration unevenness. Sometimes. In addition, when the wall surface temperature of the flash drum is too high, there is a problem that the polymer solution staying at the lower part of the flash drum boils and it becomes difficult to draw out, or the polymer deteriorates on the wall surface.
[0010]
If at least one of these occurs, the concentration of the polymer solution staying in the flash drum becomes non-uniform, and this may hinder the stable operation of the extraction pump. It was difficult. These phenomena are also observed during the start-up / shut-down operation and in the method of concentrating the solution polymerization using a large amount of a solvent and the continuous bulk / solution polymerization method of a styrene resin using a relatively small amount of the solvent. This is remarkable in the devolatilization operation containing several percent of the unreacted monomer or solvent as described in Japanese Patent Publication.
[0011]
[Problems to be solved by the invention]
The present invention overcomes the problems of the flash drum operation that is involved in flash concentration from the conventional polymer solution as described above, easily maintains a uniform polymer solution concentration inside the flash drum, and continuously An object of the present invention is to provide a method capable of efficiently concentrating volatile components from a polymer solution for the purpose of enabling stable operation.
[0012]
[Means for Solving the Problems]
Therefore, as a result of intensive studies on the control of the jacket, etc. to enable stable operation of the flash drum when the polymer solution is flash-concentrated, the jacket temperature of the gas phase portion is changed to a staying polymer solution in the liquid phase portion after flashing. It is introduced into a flash drum that is kept above the temperature and the jacket temperature in the liquid phase is kept below the temperature of the staying polymer solution after flushing, and then introduced into the polymer solution containing the volatile components after the amount of heat necessary for volatilization is introduced and flash concentrated. Thus, by removing the volatile component, it was found that condensation of the solvent, boiling of the staying polymer and thermal deterioration of the polymer on the wall surface can be prevented at the same time, and the present invention has been made.
[0013]
Hereinafter, the present invention will be described in detail.
In the present invention, when a volatile component is flash-concentrated from a polymer solution containing a volatile component composed of a solvent, an unreacted monomer and / or a by-product, a heat amount necessary for volatilization of the volatile component of the polymer solution is given, The jacket temperature in the gas phase is kept higher than the temperature of the staying polymer solution in the liquid phase after the flash, and the jacket temperature in the liquid phase is kept lower than the temperature of the staying polymer solution after the flash, and concentrated by flash. And a method for concentrating the polymer solution to remove the volatile components.
[0014]
Further, in the flash concentration of the volatile component, at least two jackets each capable of independently controlling the temperature are provided, and the retained polymer solution in the liquid phase portion after flashing the jacket temperature in the gas phase portion with the jacket. This is a method for concentrating a polymer solution in which the volatile components are removed by introducing the flash drum into a flash drum which is kept higher than the temperature and the jacket temperature of the liquid phase part is kept lower than the temperature of the staying polymer solution after flashing.
[0015]
Preferably, the jacket temperature of the gas phase part of the flash drum is kept at 10 ° C. or more higher than the staying polymer solution temperature in the liquid phase part after flashing, and the jacket temperature of the liquid phase part is kept 5 ° C. or more lower than the staying polymer solution temperature after flashing. This is a method for concentrating a polymer solution, which is introduced into a held flash drum and concentrated by flash to remove the volatile components.
[0016]
The present invention is applicable to a polymer solution containing a polymer as a main component and containing a solvent, an unreacted monomer and / or a by-product volatile component. The flashing method is not particularly limited, and can be performed by a general method applied to a polymer solution. For example, a method of feeding a flash drum having a controlled pressure through a flash valve after applying a sufficient amount of heat to volatilize a volatile component, or JP-A-61-97302 and JP-A-61-228012. A method of feeding a polymer solution to a plate fin type heat exchanger or a vertical tube type heat exchanger directly connected to a flash drum as described in the publication, and preheating by foaming volatile matter while heating Can also be raised. Further, as described in JP-A-51-134781, there is a method of preheating by foaming in advance.
[0017]
First, the amount of heat sufficient for volatilization of the volatile component of the polymer solution varies depending on the monomer, solvent, polymer, etc. used, but the volatile component is targeted within a range that does not impair the original properties of the polymer such as decomposition and coloring. It is necessary to give the amount of heat to be evaporated. As an example, in the method of feeding to a flash drum whose pressure is controlled via a flash valve, for example, in the case of a polymer solution mainly composed of SBS (styrene-butadiene block copolymer) described later, it is sufficient to flash. It is necessary to provide a suitable temperature of 100 to 200 ° C, preferably 150 to 180 ° C. In the case of a polystyrene resin, it is necessary to give a temperature of 180 to 300 ° C, preferably 200 to 250 ° C.
[0018]
In the present invention, when the volatile component is removed by flash concentration, the jacket temperature of the gas phase portion of the flash drum is maintained higher than the staying polymer solution temperature of the liquid phase portion after the flash, and the jacket temperature of the liquid phase portion is set. It is necessary to keep the temperature below the staying polymer solution temperature after flushing. For example, when operating a flash drum that has only one jacket for temperature control of the wall surface, if the jacket temperature of the flash drum is too low, the evaporated solvent will escape from the flash drum wall surface. If the flash drum wall surface temperature is too high, the polymer solution staying at the bottom of the flash drum will boil, or the polymer will cause thermal degradation on the wall surface. Therefore, as described above, it is necessary to divide the flash drum into two parts and control the temperature respectively.
[0019]
Furthermore, the jacket temperature of the gas phase part of the flash drum is kept at 10 ° C. or more higher than the staying polymer solution temperature of the liquid phase part after flushing, and the jacket temperature of the liquid phase part is 5 ° C. higher than the staying polymer solution temperature after flushing. It is preferable to remove the volatile components by introducing into a flash drum kept at a low level and flash concentration. However, it is preferable to keep the jacket temperature of the liquid phase part at least 5 ° C. lower than the temperature of the staying polymer solution, but in order to prevent polymer adhesion on the wall surface of the flash drum, the temperature should be higher than the temperature at which the fluidity of the polymer solution can be secured. It is necessary to.
[0020]
The jacket temperatures of the gas phase portion and the liquid phase portion of the flash drum are at least two jackets that can be controlled independently of each other, and the temperature is controlled by the jackets. In particular, the temperature is controlled as described above with the jacket provided in the gas phase portion of the flash drum and the jacket provided in the liquid phase portion.
[0021]
The polymer solution to which the present invention can be applied performs (co) polymerization of a monomer or the like in a solvent, contains the polymer as a main component at the end of the polymerization, and contains a solvent, an unreacted monomer, and / or a by-product volatile component. Any polymer solution may be used. The type of (co) polymerization reaction includes radical polymerization, living anion polymerization, and coordination polymerization, but is not limited thereto. For example, polymers obtained by bulk polymerization, solution polymerization, etc. using organic solvents, aromatic vinyl hydrocarbons, vinyl compounds, conjugated dienes, rubbery polymers, polymerization initiators, chain transfer agents, stabilizers, etc. Applied to the solution.
[0022]
Examples of the organic solvent used in the present invention include aliphatic hydrocarbons such as butane, pentane, hexane, isopentane, heptane and isooctane, alicyclic hydrocarbons such as cyclopentane, methylcyclopentane, cyclohexane and methylcyclohexane, or benzene. Aromatic hydrocarbons such as toluene, ethylbenzene and xylene can be used, but this is not a limitation.
[0023]
Aromatic vinyl hydrocarbons include styrene, o-methylstyrene, p-methylstyrene, p-tert-butylstyrene, 2,4-dimethylstyrene, 2,5-dimethylstyrene, α-methylstyrene, vinylnaphthalene, vinyl There are anthracene and the like, but styrene is a particularly common one.
[0024]
Examples of vinyl compounds include, but are not limited to, acrylonitrile, methyl methacrylate or ethylene.
[0025]
Conjugated dienes include 1,3-butadiene, 2-methyl-1,3-butadiene (isoprene), 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 1,3-hexadiene, and the like. However, particularly common ones include 1,3-butadiene and isoprene.
[0026]
The rubbery polymer may be rubbery at room temperature. For example, polybutadiene rubber, styrene-butadiene copolymer rubber, block styrene-butadiene copolymer rubber, ethylene-propylene copolymer rubber, acrylic Examples thereof include rubber and butadiene-acrylonitrile copolymer rubber, and these are used alone or in combination of two or more.
[0027]
Polymerization can also be carried out by thermal polymerization without using a polymerization initiator. When a polymerization initiator is used, in the case of radical polymerization, methyl ethyl ketone peroxide, 1,1-bis (t-hexylperoxy) 3,3,5-trimethylcyclohexane, 1,1-bis (t -Hexylperoxy) cyclohexane, 1,1 bis (t-butylperoxy) cyclohexane, 1,1-bis (t-butylperoxy) cyclododecane, 2,2-bis (t-butylperoxy) butane, n-butyl 4,4-bis (t-butylperoxy) valerate, 2,2-bis (4,4-di-t-butylperoxycyclohexyl) propane, α, α′-bis (t-butyl) Peroxy) diisopropylbenzene, 2,5-dimethyl-2,5-bis (t-butylperoxy) hexane, 2,5-dimethyl-2,5-bis (t-butylper) Xyl) hexyne-3, tris (t-butylperoxy) triazine, α, α′-bis (neodecanoylperoxy) diisopropylbenzene, 2,5-dimethyl-2,5-bis (2-ethylhexanoylper) Oxy) hexane, 2,5-dimethyl-2,5-bis (m-toluylperoxy) hexane, 2,5-dimethyl-2,5-bis (benzoylperoxy) hexane, bis (t-butylperoxy) Isophthalate, bis (t-butylperoxy) hexahydroterephthalate, bis (t-butylperoxy) trimethyladipate, 2,5-dimethylhexane-2,5-dihydroperoxide, 1,6-bis ( t-butylperoxycarbonyloxy) hexane, diethylene glycol-bis (t-butylperoxycarbonate) 3,3 ′, 4,4′-tetra (t-butylperoxycarbonylbenzophenone, etc. are not limited to this. In the case of living anionic polymerization, normal butyl lithium, sec-butyl lithium, oligostil lithium, oligos Examples thereof include butadienyl lithium, 1,3-bis (1-licio-1,3-dimethylpentyl) benzene, tributyltin lithium, N-lithium dihexylamide, etc. In the case of coordination polymerization And so-called heterogeneous Zieglar-Natta catalysts, soluble Zieglar-Natta catalysts, transition metal compound catalysts (so-called metallocene catalysts, half-metallocene catalysts, CGCT catalysts, etc.) activated with methylaluminoxane, boron compounds, etc. is not.
[0028]
Examples of these typical polymer solutions to which the present invention can be applied include the following.
For example, the main component is SBS (styrene-butadiene block copolymer) by living anionic polymerization using cyclohexane as the organic solvent, styrene monomer as the aromatic vinyl hydrocarbon, butadiene as the conjugated diene, and normal butyl lithium as the polymerization initiator. Polymer solution.
[0029]
Alternatively, when bulk polymerization is performed using styrene as a monomer, ethylbenzene as a solvent, and benzoyl peroxide as a polymerization initiator in the presence or absence of polybutadiene as a rubbery polymer, HIPS (impact polystyrene) is obtained. A polymer solution containing the main component is obtained. For example, about 7 parts by weight of polybutadiene is dissolved in about 75 parts by weight of a styrene monomer and about 25 parts by weight of an ethylbenzene solvent, 0.01 part by weight of benzoyl peroxide is added as a polymerization initiator, and then bulk polymerization is performed. A polymer solution based on HIPS is obtained.
[0030]
Alternatively, when styrene is used as a monomer and bulk polymerization is performed with thermal polymerization or a polymerization initiator in the presence or absence of a solvent, a polymer solution containing polystyrene as a main component is obtained. A polymer solution containing HIPS as the main component can be obtained by thermal polymerization or bulk polymerization with a polymerization initiator in the presence of polybutadiene as a rubbery polymer, styrene as a monomer, and in the presence or absence of a solvent. It is done. For example, about 7 parts by weight of polybutadiene is dissolved in about 75 parts by weight of styrene monomer and about 25 parts by weight of ethylbenzene solvent, and 0.01 part by weight of benzoyl peroxide is added as a polymerization initiator. When bulk polymerization is performed within the range, a polymer solution containing HIPS as a main component can be obtained.
[0031]
Alternatively, a polymer solution containing AS (acrylonitrile-styrene copolymer) as a main component is obtained by performing thermal polymerization using styrene and acrylonitrile as monomers and ethylbenzene as a solvent. For example, about 60 parts by weight of styrene and about 20 parts by weight of acrylonitrile as monomers, and about 20 parts by weight of ethylbenzene as a solvent are charged into a batch polymerization can and subjected to thermal polymerization, so that acrylonitrile-styrene copolymer is a main component. A polymer solution was obtained.
[0032]
The present invention is not limited to the polymer solution described above, but can be applied to any polymer solution containing a solvent, an unreacted monomer and / or a by-product volatile component.
[0033]
DETAILED DESCRIPTION OF THE INVENTION
The flash concentration method of the polymer solution of the present invention will be described. However, the present invention is not limited to the following apparatus and flash concentration method.
First, the apparatus of the present invention will be described with reference to FIG.
[0034]
(1) Flash drum shape
The flash drum 1 is generally called a flash tank, and it is preferable that the upper portion of the flash drum 1 is cylindrical and the lower portion is cone-shaped. The tip of the feed nozzle 3 for introducing the polymer solution into the flash drum must have a pressure loss in order to maintain a sufficient pressure to prevent the solvent from boiling in the pipe, and has a pore-like structure. However, the number and shape of the holes are not limited. An automatic control valve that can control an arbitrary differential pressure may be used instead of the feed nozzle. The flash drum 1 must also have a line 4 for exhausting the evaporated solvent. There must be at least one exhaust line 4 and two or more exhaust lines are desirable.
Furthermore, in order to prevent entrainment of polymer droplets in the exhaust line 4, it is preferable to attach a baffle plate (skirt) 16 around the polymer solution introduction part. As shown in FIG. 1, the baffle plate is preferably attached in close contact with the ceiling of the flash drum 1 and has a cylindrical shape. The internal area formed by the horizontal cross section of the baffle plate 16 is preferably in the range of 5-60% of the internal area formed by the horizontal cross section of the cylindrical portion of the flash drum 1, more preferably 10-50%, and more preferably 15-40%. Is most preferred. If it is less than 5%, the flashed polymer solution adheres to the inside of the baffle plate 16, and if it exceeds 80%, the effect of preventing entrainment of droplets is small. The length of the baffle plate 16 is preferably 10 to 100% of the length of the cylindrical portion of the flash drum 1, more preferably 20 to 90%, and most preferably 30 to 80%. If it is less than 10%, the effect of reducing entrainment is small, and if it exceeds 100%, the liquid level of the polymer solution staying inside the flash drum 1 comes into contact when the polymer discharge is temporarily stopped due to a malfunction of the gear pump 14. The effect of preventing entrainment of splashes does not increase.
Furthermore, a device for extracting the staying polymer must be installed in the lower part, and a gear pump 14 is generally used, but this is not restrictive. Further, before the polymer solution is introduced into the flash drum 1, it is necessary to give a sufficient amount of heat to flash in the flash drum 1, and the polymer solution is heated to a sufficient temperature. The heating method is generally a method of heating through the heat exchanger 2.
[0035]
(2) Jacket shape
The jackets 8 and 11 are provided to heat, insulate or cool the wall surface of the flash drum 1, maintain the jacket temperature of the gas phase portion higher than the staying polymer solution temperature of the liquid phase portion after the flash, and The jacket temperature is controlled so as to be kept lower than the temperature of the staying polymer solution after flushing, and it is preferable that at least two or more jackets are installed vertically. One has a structure in which the temperature of the wall surface in contact with the staying polymer solution 10 can be controlled, and the other has a structure in which the polymer solution is not staying and the temperature of the wall surface in contact with the gas phase part can be controlled. ing. The effect can be obtained with two upper and lower jackets, but more jackets may be installed. Although a small amount of the concentrated polymer solution stays in the flash drum, it is desirable that the interface of the liquid phase part is lower than the upper end of the jacket of the liquid phase part. If the liquid phase interface is below the upper end of the jacket of the liquid phase part, a part of the gas phase part has a jacket lower than the staying polymer solution temperature. If the temperature is higher than the staying polymer solution temperature, there is no problem.
[0036]
(3) Jacket temperature control
The temperature of the jacket is set so that the surface temperature of the upper jacket 8, that is, the wall surface contacting the gas phase portion, is higher than the boiling point of the solvent in the polymer solution. Preferably, the temperature is controlled to be 10 ° C. or more higher than the staying polymer solution temperature after flushing. The jacket temperature is controlled so that the surface temperature of the lower jacket 11, that is, the wall surface contacting the staying polymer solution 10 is lower than the staying polymer solution temperature, preferably 5 ° C. or more. Examples of the heat medium or refrigerant used for controlling the temperature of the jacket include hot oil, steam, heated water, water, air, and chiller water.
[0037]
【Example】
Hereinafter, the present invention will be described in detail with reference to examples. However, the present invention is not limited by the following examples.
[0038]
Example 1
(1) This experiment was performed using the apparatus shown in FIG. A 30% by weight solution of a block copolymer of styrene-butadiene obtained by performing living anionic polymerization using normal butyl lithium as a catalyst and cyclohexane as a solvent was added with water corresponding to 10 times the number of moles of the added catalyst to form active terminals. Then, carbon dioxide gas was absorbed to neutralize the catalyst residue, and a stabilizer was added to perform initial treatment. By passing this solution through the heat exchanger 2, the temperature is heated from 70 ° C. to 180 ° C., and 200 L / hr is applied to the 500 L flash drum 1 continuously maintained at 0.1 MPa while maintaining the inside of the pipe at 1.0 MPa. Introduced in.
(2) The flash drum 1 is provided with an exhaust line 4 and a vacuum pump is installed at the exhaust line 4, and the internal pressure is maintained at 0.1 MPa. Two jackets 8 and 11 are installed so that the temperature of the wall surface contacting each of the gas phase portion and the liquid phase portion where the polymer solution stays can be controlled. The upper jacket 8 (having the heating medium outlet 6 and the heating medium inlet 7) has a hot oil temperature of 115 ° C., and the lower jacket 11 (having the heating medium outlet 12 and the heating medium inlet 13) has a hot oil temperature of 80 ° C. Controlled, approximately 50 L of the polymer solution was retained in the lower part of the flash drum 1, and was extracted by the gear pump 14 so that the amount of the retained polymer solution 10 was kept constant.
(3) The flashed polymer solution was extracted from the sample outlet 15 and the polymer concentration was measured, and it was 58% by weight. The temperature of the polymer solution 10 staying was 90 ° C. The temperature was measured with a thermometer 9 for measuring the liquid phase temperature.
(4) When the internal state of the flash drum 1 was visually observed from the observation window 5, condensation and reflux of the evaporated solvent on the vapor phase tank wall were not observed, and boiling of the staying polymer solution 10 was not observed. . The extraction by the gear pump 14 could be performed stably.
[0039]
Example 2
The experiment was performed under the same conditions as in Example 1 except that the hot oil temperature of the upper jacket 8 was 95 ° C. The polymer concentration after flashing was 58% by weight, and the temperature of the staying polymer solution 10 was 90 ° C. When the inside of the flash drum 1 was visually observed from the observation window 5, the staying polymer solution 10 did not boil. Condensation and reflux of the solvent were hardly observed on the wall surface in contact with the gas phase portion, and it was possible to carry out stably without affecting the extraction by the extraction gear pump 14.
[0040]
Example 3
(1) A mixed liquid in which 90 parts by weight of a styrene monomer, 10 parts by weight of ethylbenzene and 0.01 part by weight of 1,1-bis (t-hexylperoxy) 3,3,5-trimethylcyclohexane are mixed is used as a raw material. Continuous solution polymerization of styrene was carried out by continuously supplying two continuous mixing tanks connected in series so that the internal liquid temperatures were 130 ° C. and 150 ° C., respectively, at a rate of 72 kg / hr. The polymer concentration at the outlet of the complete mixing tank group was 70% by weight.
(2) This polymerization solution was continuously supplied to the flash concentrator having the configuration of Example 1. The supplied polymer solution is heated to a temperature of 220 ° C. in the heat exchanger 2 and the internal pressure is continuously maintained at 67 KPa while maintaining the inside of the pipe at 5 MPa. The hot oil temperature of the upper jacket is 200 ° C. The temperature was supplied to the flash drum 1 controlled at 170 ° C. About 50 L of the polymer solution after flashing was retained in the flash drum 1 and continuously extracted with a gear pump 14 and supplied to a twin-screw devolatilizing extruder to obtain pellets.
(3) The flashed polymer solution 10 was sampled from the outlet 15 and the polymer concentration was measured to be 91% by weight. The temperature of the polymer solution 10 staying was 181 ° C.
(4) When visually observed from the observation window 5 inside the flash drum 1, condensation and reflux of the evaporated monomer and solvent on the gas phase wall were not observed, and boiling of the staying polymer solution 10 was not observed. The extraction by the gear pump 14 could be performed stably.
[0041]
Comparative Example 1
The experiment was performed under the same conditions as in Example 1 except that the hot oil temperature of the upper jacket 8 was 85 ° C. The polymer concentration after flashing was 55% by weight, and the temperature of the staying polymer solution 10 was 89 ° C. When the inside of the flash drum 1 was visually observed from the observation window 5, it was confirmed that although the staying polymer solution 10 did not boil, condensation and reflux of the solvent occurred on the wall surface in contact with the gas phase portion. It was done. At the same time, the discharge pressure of the extraction pump was disturbed, the extraction by the gear pump 14 became unstable, and the operation state of the subsequent processes became unstable.
[0042]
Comparative Example 2
The experiment was performed under the same conditions as in Example 1 except that the hot oil temperature of the lower jacket 11 was set to 100 ° C. The polymer concentration after flashing was 59% by weight, and the temperature of the staying polymer solution 10 was 96 ° C. When the inside of the flash drum 1 was visually observed from the observation window 5, the condensation of the solvent did not occur on the wall surface in contact with the gas phase portion, but the staying polymer solution 10 had boiled. At the same time, an extraction failure by the gear pump 14 occurred.
[0043]
Comparative Example 3
The experiment was performed under the same conditions as in Example 3 except that the hot oil temperature of the upper jacket 8 was set to 170 ° C. The polymer concentration after flashing was 89% by weight, and the temperature of the staying polymer solution 10 was 178 ° C. When the inside of the flash drum 1 was visually observed from the inspection window 5, the boiling of the staying polymer solution 10 did not occur, but the condensation and reflux of the solvent occurred on the wall surface in contact with the gas phase portion. confirmed. At the same time, the discharge pressure of the extraction pump was disturbed, the extraction by the gear pump 14 became unstable, and the operation state of the subsequent processes became unstable.
[0044]
【The invention's effect】
By adopting the method of the present invention, in concentrating the flash from the polymer solution, the problems of the operation of the conventional flash drum are overcome, and the concentration of the polymer solution inside the flash drum is easily kept uniform, continuously. Stable operation can be achieved, and volatile components can be efficiently concentrated from the polymer solution.
[Brief description of the drawings]
FIG. 1 is a schematic diagram of a concentration apparatus used in an example of the present invention.
[Explanation of symbols]
1. Flash drum
2. Heat exchanger
3. Feed nozzle
4). Exhaust line
5. Peep window
6). Upper jacket heating medium outlet
7). Upper jacket heating medium inlet
8). Upper jacket
9. Thermometer for measuring liquid phase temperature
10. Residual polymer solution
11. Lower jacket
12 Lower jacket heating medium outlet
13. Lower jacket heating medium inlet
14 Extraction gear pump
15. Sampling port
16. Baffle board (skirt)

Claims (8)

In flash concentration of a volatile component from a polymer solution containing a volatile component composed of a solvent, an unreacted monomer and / or a by-product, a heat amount necessary for volatilization of the volatile component is given to the polymer solution, A flash drum in which a cylindrical baffle plate and at least two jackets each capable of independently controlling temperature are attached around the introduction portion to the flash drum , and the jacket temperature of the gas phase portion is controlled by the jacket. The temperature is maintained higher than the temperature of the staying polymer solution in the liquid phase portion after flushing, and at the same time , the jacket temperature of the liquid phase portion is introduced into a flash drum kept lower than the temperature of the staying polymer solution after flashing and flash concentration is performed to remove the volatile components. A method for concentrating a polymer solution. The cylindrical baffle plate has an internal area formed by a horizontal cross section of 5-60% of an internal area formed by a horizontal cross section of the cylindrical portion of the flash drum, and the length of the cylindrical baffle plate is The method for concentrating a polymer solution according to claim 1, wherein the concentration is 10 to 100% of the length. Flash drum jacket temperature in the vapor phase liquid phase portion of the retention polymer solution temperature increased and held 10 ° C. or higher than after flash, simultaneously held liquid phase portion of the jacket temperature after flash dwell polymer solution temperature from 5 ° C. or more lower 3. The method for concentrating a polymer solution according to claim 1 or 2, wherein the volatile component is removed by introduction into a flash drum prepared and flash concentration.   The method for concentrating a polymer solution according to any one of claims 1 to 3, wherein a polymer solution having a polymer concentration of 20 to 40% by weight is concentrated to 50 to 90% by weight.   5. The volatile component is removed from a polymer solution that is an aromatic vinyl-conjugated diene copolymer using a hydrocarbon as a solvent or a hydrogenated product thereof. 6. Method for concentrating polymer solution.   6. The method for concentrating a polymer solution according to claim 5, wherein the aromatic vinyl-conjugated diene copolymer is a styrene-butadiene block copolymer. A polymer solution concentrating device for use in the polymer solution concentrating method according to any one of claims 1 to 6, comprising a cylindrical baffle plate around the introduction portion of the polymer solution into the flash drum, each independently. A flash drum having at least two jackets capable of temperature control, each having a jacket capable of individually controlling a temperature of a gas phase portion and a liquid phase portion, wherein the baffle plate is formed by a horizontal section thereof A polymer solution characterized in that the internal area is 5 to 60% of the internal area formed by the horizontal section of the cylindrical part of the flash drum, and the length is 10 to 100% of the length of the cylindrical part of the flash drum Concentration device.   8. The apparatus for concentrating a polymer solution according to claim 7, wherein the flash drum has a cylindrical shape at the top and a cone at the bottom.

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