JPH0532792A - Production of granular polymer - Google Patents

Abstract

PURPOSE:To efficiently obtain a granular polymer reduced in residual solvent amount by evaporating and removing an inert solvent from a polymer solution in simple operation using a simple device. CONSTITUTION:A solution of a polymer in an organic solvent (e.g. methylene chloride) is fed to a granulation band in which a granular polymer (e.g. polycarbonate) retained in an atmosphere substantially free from steam and evaporating the organic solvent and simultaneously uniformly stirred exists and the organic solvent is evaporated while bringing the solution into contact with the granular polymer. Furthermore, the concentration of the polymer dissolved in the solvent is 3-70wt.%, preferably 10-60wt.%.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing polymer granules, and more particularly to a method for efficiently producing polymer granules (powder) by removing an organic solvent from a solution of a polymer in an organic solvent by evaporation.

[0002]

The interfacial polycondensation method is preferably used as a method for industrially producing polymers such as polycarbonate, polyarylate and polyester polycarbonate. In this interfacial polycondensation method, for example, in polycarbonate,
The emulsion solution obtained after completion of the reaction is washed and separated to obtain a methylene chloride solution of polycarbonate. The polycarbonate is then manufactured by isolating it from a methylene chloride solution (PCM) of this polycarbonate. Various methods have been studied as a method for isolating the polycarbonate from the solution of the polycarbonate in methylene chloride. For example, a method of adding a poor solvent to a polycarbonate solution (Japanese Patent Publication No. 42-14474), a crushing method using a kneader that utilizes crystallization of a polycarbonate solution (Japanese Patent Publication No. 53-15899), and a method of adding it to hot water ( JP-A-60-115625) and the like. However, in any of these methods, the equipment cost is high as a method for isolating a polymer such as polycarbonate, and there is a cost problem. Therefore, there is a need for a more simplified isolation method to reduce costs.

As a method of solving these problems, Japanese Patent Publication Sho 60
The improved technology is disclosed in Japanese Patent Publication No. 54329 and Japanese Patent Publication No. 45648/1990. However, in the method disclosed herein, when evaporating methylene chloride as a solvent, water vapor, nitrogen gas, etc. are all required, and there is a problem in recovering the removed solvent. Further, there is a drawback that only polymer particles having a large particle size can be obtained, and a great amount of equipment and energy are required to remove the solvent. Further, there is a drawback in that water collects in the system and an operation of draining water is required, and at the same time, the polymer obtained contains a large amount of water.

In view of the above situation, the present inventors have developed a method for producing high-quality polymer granules that is low in cost, simpler, and less likely to mix other components into the obtained polymer. As a result, repeated intensive studies. As a result, it has been found that the above object can be achieved by bringing an organic solvent solution of a polymer into contact with the polymer particles under specific conditions. The present invention has been completed based on such findings.

[0005]

That is, the present invention provides a method for producing polymer particles from a solution of a polymer in an organic solvent, which is substantially free of water vapor and is maintained in an atmosphere in which the organic solvent evaporates. Polymer granules characterized in that an organic solvent solution of a polymer is supplied to a granulation zone where the polymer granules that are uniformly stirred exist, and the organic solvent is evaporated while the solution is in contact with the polymer granules. A method of manufacturing a body is provided.

In the present invention, the target polymer is
Polycarbonate and polyarylate are most suitable, but various other polymers produced by solution polymerization, such as polyester polycarbonate and polyamide, may also be used. Among them, for example, the polycarbonate solution is obtained by a usual polycondensation reaction, and can be easily produced by reacting a dihydric phenol with phosgene or a carbonate compound. Here, as the dihydric phenol, for example, hydroquinone; 4,4′-dihydroxydiphenyl; bis (4-hydroxyphenyl) alkane [bisphenol A and the like]; bis (4-hydroxyphenyl) cycloalkane; bis (4-hydroxy) Phenyl) oxide; bis (4-hydroxyphenyl) sulfide; bis (4-hydroxyphenyl) sulfone; bis (4-hydroxyphenyl) ketone and the like, and halogen-substituted compounds thereof. Examples of the carbonic acid ester compound include diaryl carbonate such as diphenyl carbonate and dialkyl carbonate such as dimethyl carbonate and diethyl carbonate. And, for example, according to the phosgene method, most commonly, bisphenol A and phosgene are reacted in the presence of a catalyst of a tertiary amine (such as triethylamine) in an inert solvent such as methylene chloride (methylene chloride). Can be obtained by

On the other hand, the polyarylate solution is also obtained by an ordinary polycondensation reaction and can be easily produced by reacting a dihydric phenol with terephthalic acid dichloride, isophthalic acid dichloride or the like. Here, as the dihydric phenol, hydroquinone; 4,4′-dihydroxydiphenyl; bis (4-hydroxyphenyl) alkane [bisphenol A and the like]; bis (4-hydroxyphenyl) cycloalkane; bis (4 -Hydroxyphenyl) oxide; bis (4-hydroxyphenyl) sulfide; bis (4-
Hydroxyphenyl) sulfone; bis (4-hydroxyphenyl) ketone and the like and halogen-substituted compounds thereof.

The organic solvent used in the present invention may be any solvent that is substantially inert to the polymer, is substantially stable at the temperature of use, and dissolves the polymer. However, for those having a high boiling point, it is necessary to raise the heating temperature of the polymer solution in order to efficiently devolatilize the solvent. Therefore, considering removal of the organic solvent from the polymer particles, it is preferable to use an organic solvent having a boiling point of 200 ° C. or lower. Examples of the organic solvent include, for example, methylene chloride, which is usually used preferably for polycarbonate, and chlorine-based solvents such as chloroform and chlorobenzene, as well as benzene, toluene, xylene, acetone, methyl ethyl ketone, ethyl acetate, dioxane, and tetrahydrofuran. Or a mixture thereof, and aliphatic alkanes such as heptane, hexane, pentane and the like which are mixed without any problem in dissolving them substantially may be mixed.
And these solvents may contain a poor solvent to the extent that the polymer does not precipitate. Here, as the poor solvent,
Aromatic compounds such as benzene, toluene, xylene, alkanes such as pentane, hexane, heptane, octane,
It is a ketone such as acetone or methyl ethyl ketone, or a mixed solvent thereof. These poor solvents may be vaporized and supplied as vapor, and either a method of supplying an organic solvent solution of a polymer to a granulation tank or a method of directly supplying it to the granulation tank may be adopted.

The concentration of the polymer dissolved in the above solvent is
3 to 70% by weight, preferably 10 to 60% by weight is suitable. If this concentration is less than 3% by weight, the amount of the solvent to be recovered increases and the productivity decreases, which is not efficient. Also,
When it exceeds 70% by weight, it becomes solid and the fluidity is lowered, and it is not preferable because it is difficult to supply the solvent to the solvent removing device and operate. It should be noted that when the concentration of the polymer organic solvent solution is 40% by weight or more, gelation occurs in some cases, but gelation does not cause any problem.

An organic solvent solution of a polymer prepared by using the above-mentioned organic solvent is a granulation zone (for example, a granulation zone in which polymer particles are kept in an atmosphere in which the organic solvent evaporates and are uniformly stirred). Granulation tank, granulator, etc.). The supply amount of the organic solvent solution of the polymer varies depending on various situations and cannot be uniquely determined, but is usually 250 per hour with respect to the retention amount of the polymer particles in the granulation zone.
It is not more than 100% by weight, preferably not more than 100% by weight per hour.
If the supply amount is small, the productivity is lowered, and if the supply amount is large, the amount of the residual solvent in the obtained polymer granules is increased and the quality is deteriorated, which is not preferable. Then, as a method of supplying the polymer, an organic solvent solution of the polymer may be dropped or allowed to flow down to the polymer particles retained in the granulation tank. Alternatively, it may be supplied into the flowing polymer particles. Furthermore, the organic solvent solution of the polymer is heated and pressurized,
It may be flushed in the granulation zone. When the concentration of the polymer in the organic solvent solution becomes high (40% by weight or more), the fluidity of the organic solvent solution may be slightly deteriorated.
In such a case, it is advisable to feed the granulating tank at the same time as it is discharged from the heater.

Next, the operating conditions of the solvent removing device may be such that the granulation zone is maintained in an atmosphere in which the organic solvent evaporates. Usually, the temperature is 0 to 200 ° C., preferably 30 to 150 ° C.
Held in. When the temperature in the granulation zone is less than 0 ° C, the evaporation rate of the organic solvent is slowed, the productivity is lowered, and the efficiency becomes low, which is not preferable. On the other hand, if the temperature exceeds 200 ° C., deterioration of the obtained polymer or decomposition of the solvent begins, which is not preferable. The pressure in the granulation zone may be any of reduced pressure, normal pressure and increased pressure, but is 0.1 to 11 kg / cm ² abs, preferably
It is maintained at 0.5-5 kg / cm ² abs. Pressure is 0.1 kg / cm ² a
If it is less than bs, the vacuum operation is costly and not preferable.
On the other hand, if it exceeds 11 kg / cm ² abs, the evaporation rate of the organic solvent becomes slow, and a pressure resistant granulating tank or the like is required, which is disadvantageous in terms of cost and is not preferable. The residence time of the polymer in the granulation zone is 0.01 to 10 hours, though it depends on the supply amount of the polymer in the organic solvent solution. If the residence time is short, the amount of particles retained becomes small, and sufficient stirring and mixing cannot be expected, which is not preferable. Further, if the residence time is long, an unnecessarily large granulating tank or the like must be used, which is disadvantageous in terms of cost.

The present invention is characterized in that the organic solvent is removed from the organic solvent solution of the polymer by evaporating the organic solvent while contacting with the polymer particles. That is, in order to evaporate the organic solvent, the polymer particles are preliminarily charged in the granulation zone. Here, as the polymer preliminarily charged into the granulation zone, ready-made polymer particles may be charged at the beginning of the operation. Then, when the steady operation is started, the generated polymer granules perform the same function as the polymer granules that have been preliminarily charged, and the operation can be continuously performed, so that the polymer can be efficiently used. It can be manufactured. For example, in the case of polycarbonate, as polycarbonate granules,
Flake-shaped polycarbonate flakes (PCF) are used, and the particle size thereof is preferably in the range of 8 mesh to 200 mesh. 2 even if the particle size is less than 8 mesh
Even if it exceeds 00 mesh, the polycarbonate will be hardened and it will be difficult to pulverize it, which is not preferable. The amount of polymer particles charged in advance into the granulation zone is not particularly limited, but at the start of operation and at the time of steady operation, the polymer particles flow at least when the stirrer is operated and uniformly stirred. It should be possible. In addition,
The polymer particles at the beginning of operation may be the same or different.

Next, the method of the present invention will be described with reference to the drawings. FIG. 1 is an explanatory view showing an example of a solvent removing apparatus suitable for carrying out the method of the present invention. Further, FIG. 2 is another explanatory view showing an example of the solvent removing apparatus suitable for carrying out the method of the present invention. The granulating tank B, which is a main component of the solvent removing apparatus A, may be a vertical type or a horizontal type, and may be any type as long as it is used for mixing and stirring fluid or powder. A case of producing polycarbonate will be described with reference to FIG. First, the solvent removing apparatus A is composed of a granulating tank B equipped with a stirrer D having a stirring blade E for stirring the polycarbonate flake PCF and a temperature control jacket C. Above the granulation tank B, an organic solvent solution supply pipe 1 for introducing the organic solvent solution PCM of polycarbonate and an organic solvent exhaust pipe 2 for discharging the evaporated organic solvent MC are provided. The shape of the stirring blade E is not particularly limited, and the above polycarbonate flake PC
It is only necessary that F can be stirred uniformly and sufficiently. In the figure, P is a pressure gauge, T is a thermometer, and M is a stirring blade driving motor.

In the method of the present invention, the granulating tank B as described above is used.
The above-mentioned polycarbonate flake PCF is put therein, and the raw material polycarbonate organic solvent solution PCM is charged while being uniformly stirred by the stirring blade E. At this time, in order to reduce the amount of water remaining in the generated polycarbonate flakes (granular particles), it is necessary to make the granulation tank B an atmosphere containing substantially no water vapor. Therefore, it is preferable to remove water in the polycarbonate solution supplied into the granulation tank B in advance. The removal of water is
It can be carried out by a known method, for example, by adsorbing and removing water with an adsorbent such as a molecular sieve.

Next, in FIG. 2, the granulation tank B is preferably equipped with a jacket C capable of adjusting the temperature of the granulation tank B with a heat medium in order to evaporate the organic solvent. Further, the granulation tank B is equipped with a stirrer D having a stirring blade E for stirring the polymer particles. Then, in the granulation tank B, the organic solvent solution F of the polymer
Of the organic solvent solution for supplying and adjusting the temperature to a suitable temperature with a heater G, and an organic solvent exhaust tube 2 for discharging the organic solvent that evaporates by contacting with the polymer granules charged in the granulation tank. A condenser H for condensing the evaporated organic solvent and reusing it as the recovered solvent J is provided. Here, in the granulation tank B and the organic solvent solution supply pipe 1, poor solvent supply pipes 5 and 6 for supplying the poor solvent N can be provided as needed. Further, the granulation tank B is provided with a discharge pipe 4 having a discharge valve 3 for taking out the produced polymer granules L. In the figure, M is a stirring blade driving motor as described above.

In order to efficiently produce polymer granules with the solvent removing apparatus A shown in FIG. 2, the granulating tank B is first used.
Is maintained at a predetermined temperature by the jacket C in order to maintain the atmosphere in which the organic solvent evaporates. To the granulation tank B adjusted to a predetermined temperature, the polymer organic solvent solution F is supplied from the organic solvent solution supply pipe 1 after being heated to a predetermined temperature by a heater G if necessary. At the beginning of the operation, ready-made polymer granules are charged into the granulation tank B, and the stirrer D uniformly stirs and retains them. The organic solvent solution F of the supplied polymer evaporates the organic solvent while being brought into contact with the polymer granules L that are evenly stirred and accumulated, whereby the polymer granules L are produced. The polymer particles L produced in the granulation tank B are extracted from the discharge pipe 4 by opening and closing the discharge valve 3 and transferred to the next step.

When the method of the present invention is carried out in actual operation,
As the granulating tank, for example, Henschel mixer [manufactured by Mitsui Miike Kakoki Co., Ltd.], Nauta mixer [manufactured by Hosokawa Micron Co., Ltd.], TURBO SPHERE mixer [manufactured by Sumitomo Heavy Industries Co., Ltd.], Turbulizer [ Hosokawa Micron Co., Ltd.] and the like. As a device for mixing the granular materials, for example, a kneader, a paddle mixer, a rotary drum type mixer, a ribbon dryer, a disk dryer or the like can be preferably used. Then, as the stirring blade, a helical blade, a paddle blade, a lattice blade, a paddle blade, etc. are suitable.

In addition to the organic solvent solution of the polymer, an inert gas such as nitrogen or air may be mixed in the granulation tank within a range where there is substantially no problem. Further, the solvent evaporated and removed from the granulation tank can be condensed and collected in a cooler and reused.

The polymer granules produced in the granulation tank are continuously discharged from the discharge pipe by opening and closing a discharge valve such as a rotary valve from the lower part of the granulation tank. Further, a weir may be provided to overflow the polymer depending on the level of the polymer particles in the granulation tank. Further, when the inside of the granulation tank is pressurized, it can be discharged by utilizing the internal pressure. As a device for discharging, for example, a device provided with a screw conveyor can be used.

[0020]

EXAMPLES Next, the present invention will be described in more detail with reference to Examples and Comparative Examples. As the polycarbonate,
Teflon A2500 manufactured by Idemitsu Petrochemical Co., Ltd. was used, and this was dissolved in methylene chloride (Hiroshima Wako Pure Chemical Industries, Ltd.-special grade-) to obtain a methylene chloride solution of polycarbonate (PC.
M). In addition, polycarbonate flakes (PC
F) is Tafflon FN22 manufactured by Idemitsu Petrochemical Co., Ltd.
00 was sieved and adjusted to have an average particle size of 0.5 mm.

Example 1 PCF was added to a universal mixing stirrer 5DMV manufactured by Sanei Seisakusho Co., Ltd.
Was charged at a rate of 400 g / hr and 30% by weight of PCM was supplied with stirring. Temperature during supply is 50
The temperature and pressure were kept at -400 mmHg. The supply was continued for 10 hours, and the degree of vacuum was adjusted to -700 mmHg or less and the mixture was stirred for about 30 minutes, and then the stirrer was opened to obtain the desired product.

Example 2 The same operation as in Example 1 was carried out except that the concentration of PCM was changed to 10% by weight. Example 3 In Example 1, the temperature was 110 ° C. and the pressure was 5 kg / c.
The same operation as in Example 1 was carried out except that the temperature was maintained at m ² .

Example 4 EBERBACH Waring Blender BLENDER7011S was used, and the same EBERBACH stainless container NO.8525 was used.
Charge 100 g of CF and stir 30% by weight of PC
M was fed at a rate of 90 g / h. Temperature during supply is 60
Was ~ 70 ° C. The pressure is normal pressure (open system).
Continue supplying for 5 hours, then seal, and further vacuum degree to -7
After stirring at 30 mmHg or less for about 30 minutes, the target product was obtained.

Example 5 PCF was placed in a stirring tank having a helical blade and a capacity of 50 liters.
10 kg was charged, and 30% by weight of PCM was supplied at a rate of 9 kg per hour while stirring. The temperature during supply is 90 ° C,
The pressure was kept at -400 mmHg. During operation, the flakes produced by the two-stage damper were withdrawn by about 1.3 kg every 30 minutes and operated for 24 hours to obtain about 65 kg of PCF. The PCF, temperature 50 ℃, vacuum degree-700mmH
It was kept at g or less for about 30 minutes to obtain the intended product.

Example 6 In Example 1, the PCM feed rate was 1000 g / hr.
The same operation as in Example 1 was carried out except that Example 7 In Example 2, the PCM feed rate was 1000 g / hr.
The same operation as in Example 2 was carried out except that Example 8 In Example 1, the PCM feed rate was 2000 g / hr.
The same operation as in Example 1 was carried out except that

Comparative Example 1 Example 1 was repeated except that the amount of PCF was changed to 50 g and PCM was supplied at a rate of 40 g per hour. However, since the amount of PCF was small, it was not possible to uniformly stir, the contents became solid, and flakes were not obtained. For the flakes obtained in Examples 1 to 8 above, the average particle size, bulk density and amount of residual methylene chloride (MC) were measured for quality evaluation. The results are shown in Table 1.

[0027]

[Table 1]

Examples 9 to 14 As a granulation tank, 10 liters (with a jacket) were directly attached to the upper part of the tank with a heater having a heat transfer area of 62.5 cm ² (using 200 pound steam as a heat exchanger medium). ). PCF 1,000g in autoclave
Was charged, stirred, and kept at 50 ° C. and normal pressure. There a
Weight percent PCM was charged to the heater at bg per hour. Also,
As a poor solvent, n-heptane was supplied from the side surface of the autoclave at a rate of cg per hour. Then, when the amount of PC in the supplied PCM reached 500 g, about 500 g of PCF was repeatedly extracted from the bottom, and a total of 20 hours of operation was performed. Obtained PCF at 50 ℃ for 30 minutes at -700mm
Dried below Hg. The quality evaluation was performed on the PCF extracted for the fourth time.

Table 2 shows the values a, b and c of Examples 9 to 14 and the PCM concentration in the autoclave. In addition, for the flakes obtained in Examples 9 to 14, the average particle size, bulk density and amount of residual methylene chloride (MC) were measured as quality evaluation. The results are shown in Table 3.

[0030]

[Table 2]

[0031]

[Table 3]

[0032]

As described above, according to the present invention, the inert solvent can be removed by evaporation from the polymer solution by a simple apparatus and operation to obtain a polymer granule having a small amount of residual solvent. Therefore, the simplification of the process can be achieved, the construction cost and the running cost can be reduced, and the high quality polymer can be stably produced.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an example of a solvent removal apparatus suitable for carrying out the method of the present invention.

FIG. 2 is another explanatory view showing an example of a solvent removing apparatus suitable for carrying out the method of the present invention.

[Explanation of symbols] A: Solvent removal device B: Granulation tank C: Jacket D: Stirrer E: Stirring blade F: Organic solvent solution of polymer G: Heater H: Cooler J: Recovery solvent K: Exhaust L: Polymer granular material N: poor solvent M: Motor for agitator P: Pressure gauge T: Thermometer 1: Organic solvent solution supply pipe 2: Organic solvent exhaust pipe 3: Discharge valve 4: Discharge pipe 5: poor solvent supply pipe 6: poor solvent supply pipe (for granulation tank)

Claims (4)

[Claims] 1. A method for producing a polymer particle from a solution of a polymer in an organic solvent, wherein the polymer particle is substantially absent of water vapor, and is kept in an atmosphere in which the organic solvent evaporates and is uniformly stirred. A method for producing polymer granules, comprising supplying a solution of a polymer in an organic solvent to a granulation zone in which is present, and evaporating the organic solvent while bringing the solution into contact with the polymer granules. 2. The method for producing polymer particles according to claim 1, wherein the organic solvent is methylene chloride. 3. The method for producing polymer granules according to claim 1, wherein the polymer is polycarbonate. 4. The concentration of the polymer in the organic solvent solution is 3 to.
70% by weight, The method for producing polymer granules according to claim 1, wherein