JPH0410498B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing polycarbonate resin particles having a large bulk density and uniform particle size from a methylene chloride solution of a polycarbonate resin. Methods for obtaining solid polycarbonate resin from a methylene chloride solution of polycarbonate resin include a method of evaporating methylene chloride from the solution (for example, Japanese Patent Publication No. 38-22497), or a method of mixing the solution with a non-solvent such as toluene. A method of precipitating polycarbonate resin (for example,
31468) is known. The solid polycarbonate resin is then dried, but in order to facilitate this drying, it is desirable that the solid be moderately porous, and that processing such as pelletization by melt extrusion can be easily performed. In order to achieve this, it is desirable that the bulk density be large and the particles be uniform in size. However, the solid polycarbonate resin obtained by simply evaporating methylene chloride from the methylene chloride solution of the polycarbonate resin described above is not porous, and this solid polycarbonate resin is difficult to crush, and requires a strong power to crush it. Moreover, the pulverized polycarbonate resin has irregular particles including fine powder. Further, the polycarbonate resin obtained by mixing and precipitating the above-mentioned methylene chloride solution and non-solution of the polycarbonate resin is in the form of fine flakes with extremely low bulk density. As a result of intensive research to produce polycarbonate resin granules with good properties, the present inventors found that
A methylene chloride solution of polycarbonate resin is heated in a suspended state in a granulation tank in which a water slurry containing wet-pulverized polycarbonate resin granules is circulated to evaporate the methylene chloride, thereby increasing the bulk density. It was discovered that polycarbonate resin granules, which are moderately porous with a particle diameter of about 0.4 to 0.7 g/cm ³ and whose particle size is uniform, could be produced stably for a long period of time, and filed an application earlier (Patent Application No. 7971). As a result of further research, the present inventors have found that when the above-mentioned polycarbonate resin granules are manufactured under a specific pressure, the resulting polycarbonate resin granules have a higher bulk density, and furthermore, after separation from the water slurry, The present invention was completed after learning that the water content is extremely low. That is, the purpose of the present invention is to industrially advantageously produce polycarbonate resin granules with good properties, and this purpose is to continuously supply a methylene chloride solution of polycarbonate resin to a granulation tank. , heated while remaining suspended in water.
Methylene chloride is evaporated under a pressure of 1.1 to 50 atmospheres to produce polycarbonate resin granules, and at least a portion of the water slurry containing the polycarbonate resin granules extracted from the granulation tank is wet-pulverized to form the above-mentioned granules. This is achieved by circulating the water into the tank. The present invention will be explained in detail below. The methylene chloride solution of the polycarbonate resin targeted in the present invention can be prepared by a well-known method.
general formula (In the formula, X is

【formula】

[Formula] A divalent group represented by -O-, -S-, -SO- or _-SO2- , R is a hydrogen atom, a monovalent hydrocarbon group or a halogen atom, and they are of the same type. They may also be of different types. R' represents a divalent hydrocarbon group, and the aromatic group may have a halogen atom or a monovalent hydrocarbon group. ) A dihydroxydiaryl compound represented by
From the reaction mixture obtained by reacting phosgene or a bischloroformate of a dihydroxydiaryl compound by an interfacial polymerization method or a solution polymerization method in the presence of methylene chloride and an acid binder such as caustic alkali or pyridine. , a polycarbonate resin solution obtained by washing and removing impurities using an aqueous washing liquid. Specific examples of the dihydroxydiaryl compound represented by the above general formula include bis(4-hydroxyphenyl)methane, 1,1-bis(4-hydroxyphenyl)ethane, and 2,2-bis(4-hydroxyphenyl)ethane. enyl)propane, 2,2-bis(4-
hydroxyphenyl)butane, 2,2-bis(4
-hydroxyphenyl)octane, bis(4-hydroxyphenyl)phenylmethane, 2,2-bis(4-hydroxy-3-methylphenyl)propane, 1,1-bis(4-hydroxy-3-tertiary)
butylphenyl)propane, 2,2-bis(4-
hydroxy-3-bromophenyl)propane,
bis(hydroxyaryl)alkanes such as 2,2-bis(4-hydroxy-3,5-dibromosyphenyl)propane, 2,2-bis(4-hydroxy-3,5-dichlorophenyl)propane;
bis(hydroxyaryl)cycloalkanes such as 1,1-bis(4-hydroxyphenyl)cyclopentane, 1,1-bis(4-hydroxyphenyl)cyclohexane, 4,4'-dihydroxydiphenyl ether, 4,4'-dihydroxy-
Dihydroxydiarylethers such as 3,3'-dimethyldiphenyl ether, 4,4'-dihydroxydiphenyl sulfide, 4,4'-dihydroxy-3,3'-dimethyldiphenyl sulfide, etc. dihydroxydiaryl sulfides,
4,4'-dihydroxydiphenyl sulfoxide,
Dihydroxydiaryl sulfoxides such as 4,4'-dihydroxy-3,3'-dimethyldiphenyl sulfoxide, 4,4'-dihydroxydiphenyl sulfone, 4,4'-dihydroxy-3,3'-
Examples include dihydroxydiarylsulfones such as dimethyldiphenylsulfone. These may be used alone or in combination, but in addition to these, hydroquinone, resorcinol, dihydroxy compounds such as 4,4'-dihydroxydiphenyl, terephthaloyl chloride, isophthaloyl chloride, etc. Dicarboxylic acid halides, diamines such as piperazine, dipiperidyl, etc. may be used in combination. Methylene chloride used as a solvent for polymerization reaction is 10
About % by weight or less of other solvents, such as chloroform, carbon tetrachloride, 1,2-dichloroethane, 1,
It may contain 1,2-trichloroethane, tetrachloroethane, chlorobenzene, etc.
Such a mixed solvent is not inconvenient in the production of the polycarbonate resin granules of the present invention, and therefore can be used directly in the method of the present invention following the polymerization reaction without separating methylene chloride from other solvents. The polymer concentration of the methylene chloride solution of the polycarbonate resin targeted in the present invention is about 3 to 35% by weight, preferably about 5 to 25% by weight. In the present invention, the methylene chloride solution of the polycarbonate resin is continuously supplied to a granulation tank in which a water slurry containing wet-pulverized polycarbonate resin granules is circulated, and the methylene chloride solution is kept in a suspended state. evaporation. Hereinafter, embodiments of the present invention will be explained with reference to the drawings. FIG. 1 is a schematic diagram showing an example of an apparatus for implementing the present invention. In Figure 1, 1 is a granulation tank, 2 is a stirrer, 3
is a polymer solution inlet pipe, 4 is a make-up water inlet pipe, 5 is an evaporated methylene chloride outlet pipe, 6 is a polymer granule-containing water slurry outlet pipe, 7 is a wet grinder, 8 is a circulating water slurry inlet pipe, 9 is a product polymer A granular material-containing water slurry extraction pipe, 10 indicates a pressure adjustment valve. As the granulation tank 1, any device can be used as long as it can stir the methylene chloride solution of the polycarbonate resin in water so that it can be kept in a suspended state, but a stirring tank is usually sufficient. In the granulation tank 1, at least a part of the polymer granule-containing water slurry extracted from the outlet pipe 6 is pulverized using a wet pulverizer 7 and circulated through a circulating water slurry introduction pipe 8, and makeup water is introduced. Supply water from pipe 4, and polymer solution introduction pipe 3.
A methylene chloride solution of polycarbonate resin is continuously supplied from the tank. Although the makeup water is shown to be introduced into the granulation tank 1 from the makeup water introduction pipe 4 in FIG. 1, it is not limited to this. You may. The volume ratio of methylene chloride solution to water to form an oil-in-water suspension mixture varies depending on the type of polycarbonate resin, its molecular weight, the polymer concentration in the methylene chloride solution, etc., but it is usually a volume ratio. It is best to select from the range of 1:0.1 to 4, preferably 1:0.2 to 3. In the present invention, while maintaining the above-mentioned suspended state, under a pressure of 1.1 to 50 atm, preferably 1.1 to 50 atm.
Under a pressure of 20 atmospheres, more preferably 1.2 to 10 atmospheres,
Evaporate the methylene chloride. If the pressure is too low, the effects of the present invention cannot be expected. On the other hand, high pressure is not a disadvantage in terms of the bulk density and water content of the polycarbonate resin granules obtained, but
It is disadvantageous in terms of equipment, operation, heat source, etc. This pressure is regulated by a pressure regulating valve provided in the evaporated methylene chloride outlet pipe 5. The temperature for evaporating methylene chloride may be determined as long as the vapor pressure of methylene chloride exceeds the above pressure, and may be determined in consideration of the desired evaporation rate of methylene chloride. When methylene chloride is evaporated in this way, in the granulation tank 1, a polycarbonate resin is produced by combining the wet-pulverized product of the circulated polycarbonate resin granules and the solid polycarbonate resin produced from the supplied methylene chloride solution of the polycarbonate resin. As the granules are formed, they are continuously drawn out from the outlet pipe 6 as a water slurry containing the granules. The amount of the polycarbonate resin granules present in the granulation tank 1 is 3 times the amount of the water slurry in the granulation tank 1 from the viewpoint of stirring and handling of the water slurry.
~50% by weight, preferably about 5~40% by weight, depending on the amount of methylene chloride solution of polycarbonate resin introduced into the granulation tank 1, the amount of make-up water, and the amount of polycarbonate resin extracted from the granulation tank. It is preferable to adjust the amount of the particulate-containing water slurry to maintain the amount of polycarbonate resin particulates at a constant value within the above range. In the present invention, at least a portion of the water slurry extracted from the outlet pipe 6 is subjected to wet pulverization using the wet pulverizer 7 and circulated to the granulation tank 1, and the water slurry containing the product polycarbonate resin granules is Pull it out. As the wet pulverizer 7 used in the wet pulverization process, any type of pulverizer that can pulverize solids in a liquid can be used. Preferably, for example, a type in which stirring blades rotate at high speed, or a type in which bladed stirring blades rotate at high speed are suitable. Commercially available products of the former type include Pipeline Homo Mixer and Homo Mitsukline Mill, manufactured by Tokushu Kika Kogyo Co., Ltd., and Homo Mitsukline Mill, manufactured by Komatsu Zenoah Co., Ltd. , day integrator, etc. In the wet pulverization process, the polycarbonate resin granules in the water slurry have a particle size of 0.1 to 4.
It is preferable to crush the powder to a size of about 0.2 to 2 mm. The amount of this wet-pulverized water slurry to be circulated to the granulation tank 1 is about 10 to 99.5% by weight, preferably about 50 to 98% by weight of the water slurry extracted from the granulation tank 1. If this amount is too small, the particle size of the polycarbonate resin granules formed in the granulation tank 1 will gradually increase and become uneven, leading to inconveniences such as not being able to obtain a satisfactory product or making continuous operation impossible. . On the other hand, if the amount is too large, there will be no particular inconvenience regarding the product or operation, but the yield of the product will be reduced. The water slurry for obtaining polycarbonate resin granules as a product is shown to be extracted from the water slurry after wet pulverization through the extraction pipe 9, but it can also be extracted from the granulation tank 1 or the extraction pipe 6. In order to obtain polycarbonate resin granules from the water slurry containing polycarbonate resin granules, the granules may be separated by means such as tilting or filtration, and then dried. When using the method of the present invention, it is easily 0.45 to 0.7.
It is possible to produce polycarbonate resin granules with a high bulk density of g/cm ³ , and since the resin granules separated from the water slurry have a low water content, the burden of drying is small, which is extremely advantageous industrially. EXAMPLES The present invention will be specifically explained below with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist thereof. In addition, "%" in an Example shows "weight%." In addition, the particle size is 50% of the cumulative weight on the sieve (Dp-50)
The particle size distribution is as described in "Revised 4th Edition Chemical Engineering Handbook" published by Maruzen Co., Ltd., October 25, 1973, page 973.
It is expressed as the value of n in the Rosin-Rammler distribution formula R = 100exp (-bDp ⁿ ) (where R is on the sieve [wt%], Dp is the particle diameter [mm], and b is a constant). Example 1 and Comparative Example 1 Using the apparatus shown in FIG.
Polycarbonate resin granules having an ηsp/C of 0.52 were produced from hydroxyphenyl)propane (bisphenol A) and phosgene by an interfacial polymerization method. The granulation tank 1 was a 20 (inner diameter 26 cm) equipped with an agitator 2 with four turbine blades with a blade diameter of 16 cm and a blade width of 3 cm.
A stirring tank with a jacket was used. As circulating water slurry, water slurry outlet pipe 6
The polycarbonate resin granules extracted from
The water slurry containing % of
Using a water slurry that has been pulverized using a water slurry, while circulating this from the circulating water slurry introduction pipe 8 at a rate of 900/hr, a 15% methylene chloride solution of the above polycarbonate resin in methylene chloride is introduced from the polymer solution introduction pipe 3 at 5/hr. , Water from makeup water introduction pipe 4 to 10/
hr was introduced, methylene chloride was evaporated at an internal pressure of 1.3 atm, an internal temperature of 50° C., and a stirrer rotation speed of 240 rpm to form polycarbonate resin particles. From the discharge side of the wet pulverizer 7, 11.4/hr of water slurry was extracted from the product water slurry extraction pipe 9, and the content of the granulation tank 1 was maintained at 1.7 hr. When the extracted water slurry was centrifuged to separate polycarbonate resin granules, the water content of the granules was found to be 4.3%. When this granule was vacuum-dried at 140°C for 6 hours, its bulk density was 0.53 g/cm ³ and particle size (Dp-50).
was 1.3 mm, and the particle size distribution (n value) was 4.3. For comparison, the pressure adjustment valve 10 was opened to set the internal pressure to 1 atm, and the other operations were carried out in exactly the same manner as in Example 1. The moisture content of the obtained granules was 14.6%; The bulk density of dry matter is 0.35g/
cm ³ , particle size (Dp−50) is 1.35 mm, particle size distribution (n
value) was 3.9. Example 2 Using the same equipment as in Example 1, an internal pressure of 3.1
Polycarbonate resin granules were produced in the same manner as in Example 1, except that the atmospheric pressure and internal temperature were 80°C. The moisture content of the obtained granules was 7.1%.
The bulk density of the dry product is 0.49 g/cm ³ and the particle size (Dp
-50) was 1.5 mm, and the particle size distribution (n value) was 3.9. Example 3 Using the same apparatus as in Example 1, polycarbonate resin granules were produced in the same manner as in Example 1, except that the internal pressure was 15 atm and the internal temperature was 145°C. The moisture content of the obtained granules was 6.9%.
The bulk density of the dry product is 0.50 g/cm ³ and the particle size (Dp
-50) was 1.4 mm, and the particle size distribution (n value) was 4.2. Example 4 and Comparative Example 2 The same polycarbonate resin granules as used in Example 1 were produced using the apparatus shown in FIG. The granulation tank 1 is a 600 (inner diameter 94 cm) equipped with a stirrer 2 with four turbine blades with a blade diameter of 52 cm and a blade width of 6 cm.
A stirring tank with a jacket was used. As circulating water slurry, water slurry outlet pipe 6
The polycarbonate resin granules extracted from
% of water slurry was pulverized using a wet pulverizer 7 (manufactured by Komatsu Zenoah Co., Ltd., trademark: Komatsu Sluzer Dice Integrator), and the water slurry was pulverized from the circulating water slurry introduction pipe 8 to 10 m ³ /hr.
While circulating the 15% methylene chloride solution of the polycarbonate resin mentioned above from the polymer solution inlet tube 3.
In addition to introducing 160/hr, make-up water introduction pipe 4
280/hr of 60°C water was introduced from the tank, and the internal pressure was 1.5 atm.
Methylene chloride was evaporated at an internal temperature of 60° C. and a stirrer rotation speed of 100 rpm to form polycarbonate resin particles. From the discharge side of the wet crusher 7, 320/hr of water slurry is extracted from the product water slurry extraction pipe 9.
The content of granulation tank 1 was maintained at 600 ml. When the extracted water slurry was centrifuged to separate polycarbonate resin granules, the water content of the granules was found to be 3.8%. When this granular material was vacuum dried at 140°C for 6 hours, its bulk density was 0.59 g/cm ³ and particle size (Dp-50).
was 1.3 mm, and the particle size distribution (n value) was 4.5. For comparison, the pressure adjustment valve 10 was opened to set the internal pressure to 1 atm, and the other operations were carried out in exactly the same manner as in Example 4. The moisture content of the obtained granules was 70%; The bulk density of the dry product is 0.29g/cm ³ ,
Particle size (Dp-50) is 1.2mm, particle size distribution (n value) is
It was 2.4. Example 5 Using the apparatus of Example 4, the water slurry circulation amount was 10 m ³ /
hr, 15% methylene chloride solution of polycarbonate resin feed amount 400/hr, water 130/hr,
Polycarbonate resin granules were formed at an internal temperature of 60°C, and 230/hr of water slurry was drawn out from the discharge side of the wet grinder to maintain the content at 600°C. The extracted slurry was centrifuged to separate polycarbonate resin granules, and the moisture content of the granules was found to be 4.1%. When this granule was vacuum dried at 140°C for 6 hours, its bulk density was 0.61 g/cm ³ and particle size (Dp-50).
was 1.5 mm, and the particle size distribution (n value) was 4.6.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing an example of an apparatus for implementing the present invention. DESCRIPTION OF SYMBOLS 1... Granulation tank, 3... Polymer solution inlet pipe, 4... Makeup water inlet pipe, 5... Evaporated methylene chloride outlet pipe, 6...
Water slurry outlet pipe, 7... Wet grinder, 8... Circulating water slurry introduction pipe, 9... Product water slurry extraction pipe, 1
0...Pressure adjustment valve.

Claims (1)

[Claims] 1. Continuously supply a methylene chloride solution of polycarbonate resin to a granulation tank, heat it while maintaining a suspended state in water, and evaporate the methylene chloride under a pressure of 1.1 to 50 atmospheres to generate polycarbonate resin granules. A method for producing polycarbonate resin granules, characterized in that at least a portion of an aqueous slurry containing polycarbonate resin granules extracted from a granulation tank is wet-pulverized and circulated to the granulation tank.