JP2001139692A - Method for preparing polymer slurry - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for preparing a polymer slurry that prevents spreading of the polymer particle diameter distribution caused by distribution of the shearing force inside a device. SOLUTION: The method for preparing a polymer slurry comprises using a rotary mixer provided with an inlet for a polymer slurry comprising an organic solvent solution in which a polymer is dissolved (heretofore referred to as polymer solution) and an inlet for the poor solvent at the upper part of the mixer and a rotor with a pin at the lower part thereof, feeding the polymer solution from a side of the mixer and the poor solvent from the upper surface thereof, and bringing the polymer solution and the poor solvent into uniform contact with each other by the use of the pin disposed at the rotor that is driven by a motor, in a method for obtaining the polymer slurry comprising bringing the polymer solution into contact with a poor solvent that does not dissolve the polymer but dissolves the solvent under shearing force.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for producing a polymer slurry.

[0002]

2. Description of the Related Art As a method for recovering a polymer from a polymer solution obtained by a solution polymerization reaction or the like, and removing impurities soluble in a poor solvent or a solvent dissolving the polymer in the polymer solution, there are known methods. In general, an operation of bringing a polymer solution into contact with a poor solvent to extract a solvent in which the polymer has been dissolved into the poor solvent to precipitate the polymer is generally performed. Since the method of contact between the polymer solution and the poor solvent greatly affects the removal rate of the impurities and the solvent in the polymer solution, it is necessary to increase the removal rate of the impurities and the solvent by reducing the particle size by giving severe shearing or the like. . The obtained polymer is used after being dehydrated and dried, dissolved in an organic solvent, or pelletized. Of these, the difficulty of the dehydration and drying operation is the particle size of the polymer particles obtained by precipitation. Determined by distribution. When the amount of the fine particles is large, clogging of the filter medium in the dehydration step and reduction of the recovery rate due to scattering of the fine powder in the drying step after the dehydration, and deterioration of the working environment have been caused. Conversely, when there are many large particles, the amount of impurities and solvent remaining in the polymer increases, causing a problem of melting during drying. In order to solve these drawbacks, attempts have been made to make the polymer particle diameter uniform by continuous operation.However, a slurry having a relatively uniform particle size can be obtained by reducing the weight ratio of the polymer solution to the poor solvent. The increase in the amount causes an increase in the load in the dehydration process and an increase in wastewater. When the weight ratio of the polymer solution to the poor solvent is increased, there are portions where uniform contact cannot be obtained in the apparatus, and a polymer that does not form particles adheres to the apparatus. In addition, it is easy to cause troubles such as clogging of the apparatus because the liquid is discharged and the polymerized particles are not discharged, a stable operation can be continued for a long time, and a precipitation method capable of reducing the weight ratio between the poor solvent and the polymer solution is desired. Was rare. The specific method is roughly classified into (1) a stirring tank type in which a polymer solution and a poor solvent are brought into contact with each other by shearing of a stirrer in a stirring tank (JP-A-02-255801, JP-B-06-74282); (2) A spray method in which a polymer solution is sprayed into a heated poor solvent (JP-A-63-28)
No. 4204), and (3) an extrusion method in which a polymer solution and a poor solvent are supplied to an extruder and extruded into a slurry (Japanese Unexamined Patent Publication No.
149229) and Japanese Patent Publication No. 06-39528). In these methods, the particle diameter of the polymer slurry was not uniform, the slurry outlet was blocked, and a large amount of poor solvent was required.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for producing a polymer slurry in which the obtained polymer particle size distribution is prevented from spreading due to the distribution of shear force in the apparatus.

[0004]

According to the present invention, an organic solvent solution in which a polymer is dissolved (hereinafter abbreviated as a polymer solution) is brought into contact with a poor solvent which does not dissolve the polymer but dissolves the organic solvent under shear. In a production method for obtaining a polymer slurry, a polymer solution inlet and a poor solvent inlet are provided at the upper part, and the polymer solution is fed from the side by using a rotary mixer equipped with a rotor having a pin below the inlet. , The poor solvent is supplied from the top,
The present invention relates to a method for producing a polymer slurry in which both are uniformly contacted by a pin attached to a rotor driven by a motor.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The polymer solution used in the present invention is an organic solvent solution in which a polymer is dissolved, and specifically, a polymer solution of a polyamide resin, a polyimide resin, or the like by condensation polymerization in the solution. It is. The poor solvent used in the present invention has a function of dissolving the solvent dissolving the polymer and the impurities dissolved in the polymer solution. Examples of the poor solvent include water, methanol, ethanol, isopropyl alcohol, and a mixture thereof, which are used for ordinary precipitation of a polymer. The weight ratio of the polymer solution to the poor solvent is usually 2.5 to 4, and more preferably 4 to 6 when the fluidity of the polymer slurry is low. As the rotary mixer having the above structure used in the present invention, for example, a spiral pin mixer SPM-25 manufactured by Taiheiyo Kiko Co., Ltd.
W type is mentioned.

[0006] When the supply of the polymer solution to the apparatus is started, a steady liquid flow in the apparatus is difficult to be generated, and the polymer cannot be discharged and is easily clogged.
Preferably, the rate is increased at a rate of 10 kg / hour to 15 kg / hour per minute.

The gap between the upper surface for supplying the poor solvent and the rotor is preferably small enough not to hinder the supply of the poor solvent, and is preferably 1 mm to 2 mm.

In order to prevent blockage of the polymer solution due to contact with the poor solvent at the inlet, the direction of the inlet is preferably tangential.

In order to increase the supply amount of the polymer solution under a fixed amount of the poor solvent, the temperature of the polymer solution at the time of supply is increased to 60 ° C. to 95 ° C. in order to reduce the viscosity of the polymer solution. The temperature is preferably set to 80 ° C. to 95 ° C.

Further, in order to increase the supply amount of the polymer solution under a certain amount of the poor solvent supply amount, it is necessary to reduce the centrifugal force without reducing the shear force to the minimum necessary for contact between the poor solvent and the polymer solution. For this reason, it is preferable to optimize the number of pins on the rotor serving as a source of shear force and centrifugal force according to the viscosity of the polymer solution and the types of the solvent and the poor solvent in the polymer solution. When the solubility of the solvent and the poor solvent in the polymer solution is high, it is preferable to reduce the number of pins.

[0011]

EXAMPLES The present invention will be further described with reference to Examples. FIG.
Is the spiral pin mixer SPM-25 used in the examples.
It is a front view of W type (made by Taiheiyo Kiko Co., Ltd.). FIGS. 2 and 3 are schematic cross-sectional views of a mixer section for obtaining a polymer slurry in the vertical and horizontal directions, respectively. In the figure, a certain amount of the polymer solution is continuously supplied from the polymer solution inlet 1 and the poor solvent from the poor solvent inlet 2, and the rotor 5 with the pin 6 rotated by the power of the motor 8 rotates, The combined solution and the poor solvent are uniformly mixed in the mixing section 4. The polymer slurry generated by the mixing is scraped out by the scraper 7 and is continuously taken out from the outlet 3 to the next step or the like. 1
0 is an upper cover, 11 is a gap.

In a 130-liter stirring tank, N-
91000 g of methylpyrrolidone and 2,
Dissolve 12983 g of 2-bis [4- (4-aminephenoxy) tetramethylpropane] and 414 g of 1,3-bis (3-aminopropyl) tetramethyldisiloxane,
The mixture was cooled to 0 to 5 ° C. under a flow rate of 1 m ³ / hour of nitrogen. There, 7088 g of trimellitic anhydride chloride was added, and 20 to
The reaction was carried out at 25 ° C. for 1 hour, and 4079 g of a reaction aid, triethylamine, was added, followed by a reaction at 25 ° C. to 30 ° C. for 1.5 hours to obtain a polyamide resin. 180 ° C, nitrogen 3m
^The reaction was carried out for 5 hours under a flow rate of ³ / hour to obtain a polyamide-imide resin. The following Examples and Comparative Examples were carried out using a polymer solution comprising 22% by weight of the polyamideimide resin and 78% by weight of N-methylpyrrolidone.

Embodiment 1 Using the apparatus shown in FIG.
25 ° C. water as a poor solvent was supplied at 540 L / hour from the poor solvent inlet 2 through the polymer solution inlet 1 and brought into contact with the polymer solution to obtain a polymer slurry. The gap 11 is 7 mm
And At the start of supply, start from 50 kg / hour, increase by about 10 kg / hour per minute, and finally
g / h. The particle size of the obtained polymer was visually evaluated. Further, the dried polymer was placed in ion-treated water to examine the residual amount of chlorine ion as an impurity in the polymer solution.
After the extraction for a time, the chlorine ion content in the water was measured by ion chromatography. The chlorine ion content was 2 ppm by weight relative to the polymer.

[Comparative Example 1] Water was added to a batch mixer having a high-speed rotating cutter attached to the bottom of a 100 L internal volume tank.
kg and 25 kg of the polymer solution were added, mixed for 10 minutes, and then taken out. Table 1 shows the results of the evaluation performed in the same manner as in Example 1. There is a lot of polymer adhesion on the bottom,
Manual scraping and cleaning with an organic solvent were required. In addition, it is clear that the particle size distribution is unpreferable because it has a wide distribution of chlorine ions.

Embodiment 2 The same apparatus and operating conditions as in Embodiment 1 except that the gap 11 between the rotor 5 and the upper cover 10 shown in FIG. 1 was changed from 7 mm to 2 mm (the continuous operation time was 2 hours, hereinafter The same procedure was used to obtain a polymer slurry. Further, the results of measuring the polymer properties in the same manner as in Example 1 are shown in Table 1. As compared with Example 1, the particle diameter range was as narrow as 1 to 10 mm to 2 to 7 mm. .

[Embodiment 3] The number of pins mounted on the rotor 5 is reduced from 48 to 32. At this time, the pins were spirally pulled out so that the liquid flow in the apparatus did not become uneven. Except for this and the supply amount of the polymer solution, the same apparatus and operating conditions as in Example 2 were used to obtain a polymer slurry. Table 1 shows the results of measuring the polymer characteristics in the same manner as in Example 1. The polymer solution supply rate can be increased from 100 kg / hour to 200 kg / hour as compared with Example 2. Was. Since there was no change in the particle size range, excessive centrifugal force could be eliminated by reducing the number of pins, and the discharge property of the polymer slurry was improved.

Example 4 The temperature of the supplied polymer solution was 2
Except that the temperature was raised from 5 ° C. to 80 ° C., the procedure was carried out under the same apparatus and operating conditions as in Example 3 to obtain a polymer slurry. Table 1 shows the results of measuring the polymer characteristics in the same manner as in Example 1. However, the amount of the polymer solution supplied was 2 compared to Example 3.
It was possible to increase from 00 kg / h to 220 kg / h. By raising the temperature, the viscosity of the polymer solution was lowered, and the contact with the poor solvent and the discharge property were improved.

[0018]

[Table 1]

[0019]

The polymer slurry obtained by the present invention has a sharp particle size distribution, and is used for removing impurities dissolved in the polymer solution, dehydrating the slurry in a later step, and preventing fine powder from scattering during drying. It is suitable.

[Brief description of the drawings]

FIG. 1 is a front view of an apparatus used in an embodiment of the present invention.

FIG. 2 is a schematic vertical sectional view of the mixer unit of FIG. 1;

FIG. 3 is a schematic cross-sectional view of the mixer unit of FIG. 1 in a lateral direction.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Polymer solution inlet 2 ... Poor solvent inlet 3 ... Polymer slurry outlet 4 ... Mixing part 5 ... Rotor 6 ... Pin 7 ... Scraper 8 ... Motor 9 ... Mixer part 10 ... Top cover 11 ... Gap

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Claims (1)

[Claims] 1. A method for producing a polymer slurry by bringing an organic solvent solution in which a polymer is dissolved (hereinafter abbreviated as a polymer solution) into contact with a poor solvent which does not dissolve the polymer but dissolves the organic solvent under shear. In the method, the polymer solution is supplied from the side and the poor solvent is supplied from the top using a rotary mixer equipped with a polymer solution inlet and a poor solvent inlet at the top, and a rotor having a pin below the inlet. A method for producing a polymer slurry, wherein the two are uniformly contacted by a pin attached to a rotor driven by a motor.