JPH0458810B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a manufacturing method suitable for efficiently obtaining polycarbonate resin granules, particularly polycarbonate resin granules having high density and uniform particle size. [Prior Art and Problems Therewith] In order to obtain granules of polycarbonate resin, a methylene chloride solution of polycarbonate resin is conventionally introduced into hot water and granulated in the warm water. As an example, in Japanese Patent Publication No. 46-37424, a methylene chloride solution of polycarbonate resin is heated at 50 to 75℃.
A method is described in which hot water is injected into hot water held in a stirrer and stirred by a stirrer having cross-shaped stirring blades to form hot water in a stirred flow. However, the polycarbonate resin particles obtained by this method did not have a sufficiently high bulk density. Furthermore, JP-A-59-133228 discloses that polycarbonate resin granules are produced by introducing a methylene chloride solution of polycarbonate resin into hot water in a granulation tank, and a portion of the hot water slurry containing the granules is A method is described in which the slurry is removed from the granulation tank, wet-pulverized, and then recycled into the granulation tank for granulation. This method yields polycarbonate resin granules with a relatively high bulk density, but the granules tend to clog the piping system during recirculation, making continuous operation impossible. be. An object of the present invention is to solve the problems of the prior art described above and provide a manufacturing method that can continuously obtain polycarbonate resin granules having a sufficient bulk density from hot water. [Means for Solving the Problems] In order to achieve the above object, the present inventors have conducted various studies and found that when granulating in hot water, a certain amount of polycarbonate resin granules to serve as seeds for granulation is added to hot water. They discovered that polycarbonate resin granules with high bulk density can be obtained by introducing a methylene chloride solvent solution of polycarbonate resin while holding the body in advance and stirring hot water under specific conditions.Based on this, the present invention was completed. . That is, the structure of the present invention for achieving the above object is a method for producing polycarbonate resin granules in a stirred flow by introducing a methylene chloride solvent solution of a polycarbonate resin into stirred warm water. Polycarbonate resin granules are present, a narrow flow path is provided in the stirring flow of hot water, and a stirring blade is rotated at high speed within this flow path to apply shear force while hot water is convected at high speed to form a flow. This is a method for producing polycarbonate resin granules, characterized by: The feature of this invention is that polycarbonate resin granules are pre-existing in hot water as a seed for granule formation, and the granules are granulated while creating a turbulent flow strong enough to apply shear force during stirring. It is to be. The lower limit of the temperature of the hot water is the boiling point of methylene chloride (40° C.), and it is preferably maintained at a temperature somewhat higher than this lower limit temperature. A more preferable temperature range is 40 to 50°C. If the hot water is lower than 40°C, the evaporation rate of methylene chloride decreases, resulting in a decrease in productivity and the adhesion of polycarbonate resin particles to the stirring blades, which is undesirable. On the other hand, at temperatures above 50℃,
Block-like lumps are likely to form, and
Even if it becomes granular, the bulk density will be reduced. This seems to be because methylene chloride, which is a solvent for the polycarbonate resin, evaporates at an early stage and the polycarbonate resin precipitates in a short period of time. The methylene chloride solution of polycarbonate resin supplied in hot water usually has a polycarbonate concentration of 3 to 35% by weight, preferably 10% by weight.
degree is preferred. This is because if it is less than 3% by weight, the amount of methylene chloride to be evaporated is large, making it difficult to measure the increase in processing amount, and if it is more than 35% by weight, it may be difficult to achieve good dispersion of the polycarbonate solution in hot water. . The amount of methylene chloride solution to be supplied is determined in correlation with the amount of hot water. For example, the amount of methylene chloride solution to be supplied is 10 to 300 parts per hour per 100 parts (volume) of hot water, preferably 20 to 200 parts per hour. It is best to introduce it as part of the program. Furthermore, in order to form preferable granules, a poor solvent may be present in the methylene chloride solution of polycarbonate depending on the situation. Examples of such poor solvents include ketones such as acetone and methyl ethyl ketone, hydrocarbons such as hexane, heptane, octane, kerosene, and ligroin, and aromatic hydrocarbons such as toluene and xylene. can. Furthermore, this methylene chloride solution may contain chlorobenzene or the like together with or instead of the poor solvent. A methylene chloride solution of a polycarbonate resin is obtained by adding a dihydroxydiaryl compound and phosgene or a dihydroxydiaryl compound and a bischloroformate in the presence of methylene chloride and an acid binder such as a caustic alkali or pyridine. Examples include polycarbonate resin solutions obtained by conducting a polymerization reaction by interfacial polymerization, solution polymerization, or the like. In this invention, a methylene chloride solution of polycarbonate resin as described above is introduced into hot water,
Pre-immobilized polycarbonate resin granules are present in hot water. The polycarbonate resin particles present in hot water have an average particle size of 0.1 to 4 mm, preferably 0.2 mm.
A thickness of about 2 mm is good. The average particle size is
If it is less than 0.1 mm, it may be difficult to handle because it is a fine powder, and if it exceeds 2 mm, stirring may become uneven, which may be undesirable. The amount of this polycarbonate resin granule present in hot water is usually 10 to 300 parts per part of hot water.
g, preferably 25 to 200 g. The mixed polycarbonate resin granules present in the hot water serve as seeds for granulation of the polycarbonate resin granules. Methods for keeping polycarbonate resin granules in hot water include adding a predetermined amount of polycarbonate resin granules to hot water, and gradually adding a methylene chloride solution of polycarbonate resin to hot water to remove seeds and A method of forming polycarbonate resin granules can be adopted. The polycarbonate resin in the methylene chloride solution supplied in hot water grows using the seeds formed by the various methods described above as nuclei, and is granulated. In this invention, it is necessary to perform granulation in a specific harsh agitation flow. That is, granulation is performed using a high-speed stirring flow that imparts a strong shearing force. This shear force cannot be obtained simply by rotating stirring blades at high speed within the granulation tank. In this invention, a narrow flow path for hot water is formed in the granulation tank, and a stirring blade that rotates at high speed is provided in this flow path, and the rotation of the stirring blade applies shear force to the hot water guided into the flow path. It is something to do. As a stirring device suitable for this invention, Japanese Patent Application Laid-open No. 57
The devices disclosed in Japanese Patent Laid-open No. 42324 and Japanese Patent Laid-Open No. 62-45330 can be used, and one example is shown in FIG. 1, which is a sectional view of the stirring device. The granulation tank 1 is filled with hot water 2, and a stirring shaft 4 connected to a driving means, such as a motor 3, extends into the granulation tank 1. A turbine 5 with stirring blades is attached to the lower end of the stirring shaft 4. In addition, granulation tank 1
An appropriate number of fixing rods 6, for example three, are suspended and extended in parallel to the stirring shaft 4 inside. A bottomed cylindrical stator 7 having an opening at the bottom is attached to the lower end of the fixed rod 6. The stator 7 has a narrow flow path through which hot water can flow in the vertical direction.
The turbine 5 is inserted into this stator 7,
And it is driven to rotate at high speed within the stator 7. In this case, the turbine 5 uses stirring blades so as to guide hot water from below to above the stator 7 through its rotation.
A is provided, and the hot water that has flowed into the stator 7 is given a shearing force by the stirring blades 5A of the turbine 5. Therefore, the polycarbonate resin granules that have been pre-existing in hot water or the polycarbonate resin granules that have grown using these resin granules as seeds are subjected to the shearing force of the turbine 5 and are made into fine particles, and then are turned into fine particles in the stirring flow. The polycarbonate resin adheres to the surface, granules grow, and this cycle repeats thereafter. As a result, polycarbonate resin particles having a high bulk density and a uniform particle size can be obtained. In this case, the gap between the turbine and stator is
It is preferably about 0.5 to 1.0 mm. In addition, the rotation speed of the turbine is V (circumferential speed) in the following formula:
The rotation speed is preferably 10 or more. V=π・N・d/60 (m/sec) (N is the rotation speed of the turbine (r・p・m)
, and d is the turbine blade diameter (m). ) In FIG. 1, reference numeral 8 denotes a commutator plate that spans the middle part of the fixed rod 6, and the hot water led upward from the stator 7 collides with it and directs the flow direction of the granulation tank 1. This efficiently generates convection that changes the flow direction toward the inner circumferential surface and further downward. 10 is a tank for storing a methylene chloride solution of polycarbonate resin, and 11 is a water tank for supplying hot water to the granulation tank 1. These are connected to the upper part of the granulation tank 1 by a pipe line 12. Further, 13 is a jacket for heating the granulation tank 1, 14 is an outlet for taking out hot water and polycarbonate granules from the granulation tank 1,
When a polymer liquid is continuously supplied, a slurry containing polycarbonate resin particles is extracted. In this invention, such a granulation tank 1 is used,
Pre-solidified polycarbonate granules 5
The methylene chloride solution of the polycarbonate resin is injected from the tank 10 into the warm water 2 in which the polycarbonate resin is granulated under severe stirring conditions accompanied by shearing by the turbine 5. It can be efficiently manufactured with uniform particle size. Further, since the granulation tank 1 is internally circulated, there is no clogging of the piping system, and continuous production is possible. In addition, in the present invention, a stirrer having a configuration other than that illustrated can be used as long as it is a stirring means that applies shear force to hot water. [Examples] Hereinafter, the present invention will be further explained using Examples and Comparative Examples. Example 1 Add water to the 2 separable flasks.
1.5 and stir at 12000rpm using a Homomixer manufactured by Tokushu Kika Kogyo (turbine blade diameter 25mm) while maintaining the temperature at 45℃ in a water bath.
There, a polycarbonate resin with a bulk density of 0.53 and an average particle size of 1 mm (viscosity average molecular weight
20000) 40 g of granules were added and stirred thoroughly and uniformly, and 400 ml of a methylene chloride solution containing 10% by weight of polycarbonate resin was added dropwise at a rate of 25 ml/min. After dropping, continue stirring for another 5 minutes,
The polycarbonate resin solids were filtered off using 100 mesh and dried at 120°C for 224 hours. Table 1 shows the morphology, particle size, and bulk density of the polycarbonate resin obtained after drying. Example 2 The same procedure as in Example 1 was carried out except that 5% by weight of acetone was added in advance to the methylene chloride solution of the polycarbonate resin in Example 1. Table 1 shows the morphology, particle size, and bulk density of the polycarbonate resin obtained after drying. Example 3 A stirring tank with a 100 jacket was used as a granulation tank, and a homomixer manufactured by Tokushu Kika Kogyo Co., Ltd. (turbine diameter: 99.6 mm) was used as an agitator. A methylene chloride solution of 10% by weight of polycarbonate resin was added to the contents in the tank (including 10% by weight of polycarbonate granules with an average particle size of 1 mm) at an internal temperature of 45°C for 30 minutes. Introduced at a feed rate of 20℃
of make-up water at a feed rate of 60/hour,
Granulate in hot water while stirring at 3600 r/p/m,
A slurry of 67/hour was extracted from the bottom of the stirring tank. The extracted slurry was passed through a 100 mesh sieve, and the polycarbonate resin on the sieve was heated at 120℃ for 24 hours.
Dry for an hour. Table 1 shows the morphology, particle size, and bulk density of the polycarbonate resin obtained after drying. Comparative Example 1 The same procedure as in Example 1 was carried out except that the seed polycarbonate resin granules were not charged in advance. The recovered polycarbonate resin was in the form of fibers, and its bulk density is shown in Table 1. Comparative Example 2 A disk turbine (DS) blade with a blade diameter of 40 mm was used instead of the stirrer used in Example 1, and the rotation speed was
The same procedure as in Example 1 was carried out except that stirring was performed at 5000 r.p.m. The morphology, particle size, and
The bulk density is shown in Table 1. Comparative Example 3 The same procedure as in Example 1 was carried out, except that a paddle blade with a blade diameter of 70 mm was used instead of the stirrer used in Example 1, and stirring was performed at a rotational speed of 500 r.p.m. No particles of polycarbonate resin were obtained, and block-like particles were stuck to the paddle blade.

[Table] ×= No granules were obtained.
[Effects of the Invention] According to the present invention, polycarbonate resin granules are added and granulated in an agitated flow that imparts shear force.
Polycarbonate resin granules with uniform particle size can be efficiently produced.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing a cross section of the stirring device. 1... Granulation tank, 2... Hot water, 3... Motor, 4
... Stirring shaft, 5 ... Turbine, 6 ... Fixed rod, 7 ... Stator, 8 ... Commutation plate, 10 ... Tank, 11 ... Water tank, 12 ... Pipe line, 13 ...
...jacket, 14...discharge port.

Claims (1)

[Scope of Claims] 1. A method for producing polycarbonate resin granules by introducing a methylene chloride solution of a polycarbonate resin into stirred warm water, wherein the polycarbonate resin granules are present in the warm water, A polycarbonate resin granule, characterized in that a narrow flow path is provided in the stirring flow of hot water, and a stirring blade is rotated at high speed within this flow path to apply shearing force while causing hot water to convect at high speed and granulate. manufacturing method.