JP2002047350A - Manufacturing method of polycarbonate resin powder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of polycarbonate resin powder containing extremely little residual organic solvent and having an uniform particle size, and produced by a simple process with stability and good productivity. SOLUTION: It is characteristic that organic solvent of polycarbonate resin is heated and condensed under pressure at 40 to 120 deg.C and its concentration becomes 23 to 50% by weight and by using extrusion type evaporator which has an ability of transporting unidirectly contents from entrance to exit, the concentrated solution is flashed at the entrance and supplied as paste and solvent is removed under normal or reduced pressure at a temperature maintaining solid state and polycarbonate powder particle is obtained at the exit.

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 polycarbonate resin particles. More specifically, a polycarbonate resin powder having an extremely small amount of residual organic solvent,
The present invention relates to a method for producing a product stably with high productivity by a simple method.

[0002]

2. Description of the Related Art Polycarbonate resins are usually produced by a so-called interfacial polycondensation method in which an aqueous alkali solution of a dihydric phenol and phosgene are reacted in the presence of an organic solvent such as methylene chloride. After removing the organic solvent from the polycarbonate resin solution) to obtain a granule, the granule is subjected to a drying process.

As a method of removing the organic solvent from the polycarbonate resin solution to obtain powders, for example, a method of bringing the polycarbonate resin solution into contact with hot water or steam to form flakes or granules (Japanese Patent Publication No. 36-11231) Gazette,
Japanese Patent Publication Nos. 40-9843, 45-9875, 48-3752, 54-1
No. 22393), a method of gelling and granulating by concentration or cooling (Japanese Patent Publication No. 36-21033, Japanese Patent Publication No. 38-22497, Japanese Patent Publication No. 40-12379, Japanese Patent Publication No. 45-9875). , Tokiko 47-41
421, JP-A-51-41048) and the like.

[0004] However, many organic solvents still remain in the powder (including flakes) obtained by these methods, and it is difficult to sufficiently remove the residual organic solvents by ordinary drying. In order to further reduce the residual organic solvent, drying must be performed at a high temperature for a long time or pelletization by an extruder equipped with a vacuum devolatilization mechanism, and still, several tens to several hundreds ppm of the organic solvent remain. However, the resulting product cannot avoid adverse effects on heat resistance, hue, physical properties and the like.

As a method for producing a polycarbonate resin powder having a small amount of residual organic solvent, a method of adding a non-solvent or a poor solvent to a polycarbonate resin solution obtained by a reaction or a slurry of a polycarbonate resin in which an organic solvent remains, or A method of extracting a polycarbonate resin particle in which an organic solvent remains with a poor solvent (Japanese Patent Publication No. 55-1979)
1298, JP-A-63-278929, JP-A-64-6020, and JP-B-5-12371).

[0006] In these methods, although the organic solvent is sufficiently removed, a large amount of non-solvent or poor solvent remains on the contrary. It is difficult to sufficiently remove even by drying for a long time. In addition, when the drying is strengthened in this way, not only the operation becomes complicated, but also the molecular weight of the polycarbonate resin is reduced, the hue is deteriorated, and foreign substances are mixed.

On the other hand, as a method of granulating a non-aqueous polycarbonate resin, the polycarbonate resin granules are previously retained in a granulation tank, and the granules are stirred in an atmosphere in which the organic solvent evaporates, and the organic solvent solution is stirred. Evaporating the organic solvent while contacting the particles with the granular material (Japanese Patent Laid-Open No. 5-32792)
JP-A-8-169958, etc.) have been proposed. However, it is necessary to prepare granules in advance, and the residence time in the granulation tank tends to be long, and there are problems such as deterioration of the hue of the polymer.

Further, a method of concentrating a polycarbonate resin solution under a pressurized state, supplying the concentrated solution to a device having a kneading mechanism, concentrating at a temperature lower than the boiling point of the solution, precipitating and pulverizing the solution to obtain a granulated product (Japanese Patent Laid-Open No. Hei 8- 269187) has been proposed, but since the inside of the system is concentrated and precipitated below the boiling point of the solution,
It is difficult to continuously obtain granulated products, and it takes time to distill the solvent.

Further, a method of further elevating the temperature of the concentrated polycarbonate resin solution in a dryer, concentrating and drying, and melting and extruding the polymer into granules (JP-A-9-11).
No. 0999) has been proposed, but there is a problem that the melt drying temperature is high and the color of the extracted polymer deteriorates.

[0010]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for stably producing a polycarbonate resin powder having an extremely small amount of residual organic solvent with good productivity. .

The present inventors have conducted intensive studies to achieve the above object. As a result, a polycarbonate resin solution of 23 to 50% by weight, which was obtained by heating and concentrating a polycarbonate resin solvent solution under pressure, was extruded under normal pressure or reduced pressure. To the devolatilizer, flush and supply in paste state, while moving the contents sequentially from the supply port to the downstream side, devolatilize the solvent at a temperature that maintains the solid state, and during this time paste the contents The present inventors have found that a method of drying while changing the form from a shape to a granular material and taking out a polycarbonate resin granular material from an outlet of the extrusion type devolatilizer achieves the above object, and has reached the present invention.

[0012]

That is, according to the present invention, a polycarbonate resin organic solvent solution is mixed with
The solution is concentrated by heating at a temperature of 0 to 150 ° C. to a concentration of 23 to 5
0% by weight, and using an extrusion type devolatilizer having a function of moving the content in one direction from the inlet side to the outlet side, flushing the above concentrated solution to the inlet side and supplying the concentrated solution in a paste form, at normal pressure or A method for producing a polycarbonate resin particle is provided, wherein the solvent is removed at a temperature at which a solid state is maintained under reduced pressure, and the polycarbonate resin particle is obtained from an outlet side.

The polycarbonate resin used in the present invention is a resin usually used as an engineering resin, and is an aromatic polycarbonate resin obtained by reacting a dihydric phenol with a carbonate precursor. As the dihydric phenol used here, 2,2-bis (4-hydroxyphenyl) propane (commonly called bisphenol A) is preferably used. Other dihydric phenols include:
For example, bis (hydroxyaryl) alkanes such as bis (4-hydroxyphenyl) methane, bis (hydroxyaryl) cycloalkanes such as 1,1-bis (4-hydroxyphenyl) cyclopentane, 4,4-
Dihydroxydiphenyl and the like;
And halogenated bisphenols such as bis (3,5-dibromo-4-hydroxyphenyl) propane.

Examples of the carbonate precursor include carbonyl halide, diaryl carbonate, and haloformate, and specific examples include phosgene, diphenyl carbonate, and dihaloformate of a dihydric phenol.

In producing the aromatic polycarbonate resin by reacting the above-mentioned dihydric phenol with a carbonate precursor, a catalyst, a molecular weight modifier, an antioxidant and the like may be used as necessary. The resin may be, for example, a branched polycarbonate resin obtained by copolymerizing a trifunctional or higher polyfunctional aromatic compound, or a mixture of two or more aromatic polycarbonate resins.

Any molecular weight can be used for the aromatic polycarbonate resin. For example, when an aromatic polycarbonate resin is obtained using bisphenol A as a dihydric phenol and phosgene as a carbonate precursor, a concentration of 0.7 g / g The specific viscosity (η _sp ) measured at a temperature of 20 ° C. with a 100 ml methylene chloride solution is 0.19 to
1.5 is preferable, and 0.23 to 1.0 is more preferable.

The method for producing an aromatic polycarbonate resin powder of the present invention is extremely suitable for using an aromatic polycarbonate resin solution obtained by an interfacial polycondensation method using an organic solvent. That is, the present invention is suitable for obtaining a powder or granules from an aromatic polycarbonate resin solution obtained by reacting a dihydric phenol with phosgene in an organic solvent. The organic solvent used at this time is a good solvent for the aromatic polycarbonate resin, and is a solvent immiscible with water.

The organic solvent referred to in the present invention is at least one organic solvent.
A kind of good solvent as a main solvent, preferably 1,1,2,2
2-tetrachloroethane, methylene chloride, 1,2-dichloroethylene, chloroform, 1,1,2-trichloroethane, 1,
2-ethane dichloride, dioxane, tetrahydrofuran, dioxolan and the like can be used. Particularly preferably, methylene chloride (normal pressure boiling point: 40 ° C.) is used. As such an organic solvent, a solvent in which 90% by volume or more of the solvent is a good solvent is preferably used, and a solvent substantially consisting of a good solvent is particularly preferably used.

In the present invention, the organic solvent used may contain a poor solvent that does not precipitate the polymer. Examples of such poor solvents include aliphatic hydrocarbons such as heptane, hexane, and pentane, and aromatic hydrocarbons such as benzene, toluene, and xylene.

The polycarbonate resin solution obtained by the above-mentioned interfacial polycondensation method is usually subjected to a filtration treatment for removing insoluble impurities, and washing with water and, if necessary, acid for removing water-soluble impurities and catalysts. Alternatively, processing such as alkali cleaning is performed.

Next, the polycarbonate resin solution after the above treatment is subjected to an operation of removing the solvent to obtain polycarbonate resin powder. At this time, the concentration of the polycarbonate resin solution is usually 10 to 20% by weight. If the concentration is within this range, the solution viscosity is appropriate, it is easy to handle with industrial production equipment, the solution is easy to wash, the filtration efficiency is good, and the organic solvent is not too much, It does not require excessive energy when removing, and is advantageous in terms of economic production.

In the method for producing a polycarbonate resin particle of the present invention, the polycarbonate organic solvent solution is supplied to a concentration adjusting device having a heating device, preferably at a gauge pressure of 0.01 to 1.5 MPa, more preferably 0 to 1.5 MPa. At a temperature of 40 to 150 ° C., preferably 75 to 120 ° C. under a pressure of 0.2 to 0.8 MPa, part of the solvent is distilled off,
The solution concentration is adjusted to 23 to 50% by weight, preferably 25 to 45% by weight. As a device for pressurizing and heating the polycarbonate organic solvent solution, a heat exchanger is preferably used, and examples thereof include a double-tube heat exchanger, a multi-tube heat exchanger, and a plate-type heat exchanger.

Next, the concentrated polycarbonate resin solution is supplied in paste form while being flushed to the inlet side of the extrusion type devolatilizer. Preferably, the polycarbonate resin solution is flushed into the extrusion devolatilizer through a flush valve. The structure of the flash valve is not particularly limited, as long as it can withstand the concentration and pressure of the solution, and preferably has a pressure-adjusting control valve, and a needle valve is preferable.

The flashed polycarbonate resin solution immediately evaporates part of the solvent in the extrusion type devolatilizer to form a paste. Such a paste preferably has a solvent content of 0.3 to 0.7 in a weight ratio of (solvent) / (total amount of polycarbonate resin and solvent).

The temperature inside the extrusion type devolatilizer is such that the solid state is maintained, and the solvent contained in the polycarbonate resin is removed at such a temperature. Preferably from the boiling point of the solution to 145 ° C or lower, more preferably from 80 ° C to 1 ° C.
The temperature is maintained at 40 ° C., and the pressure in the extrusion type devolatilizer is set to normal pressure or reduced pressure. Under such conditions, the solvent tends to evaporate from the flushed polycarbonate resin solution.

The extrusion type devolatilizer preferably has a scraping mechanism inside. For example, N-S manufactured by Mitsubishi Heavy Industries, Ltd.
An extrusion devolatilizer represented by a CR dryer or a TSK-scraping dryer manufactured by Tsukishima Kikai Co., Ltd. can be used. In the extrusion type devolatilizer, the solvent contained in the polycarbonate resin is gradually devolatilized at normal temperature or reduced pressure at a temperature at which the solid state is maintained, and the organic solvent content is 10 wt. % Or less can be obtained. At this time, if devolatilization is performed at a temperature equal to or lower than the boiling point of the solution, it is difficult to continuously generate powder and granules, and it takes time to remove the solvent by evaporation, which is unsuitable for mass production equipment. Appropriate.

The thus obtained polycarbonate resin particles are pulverized by a hammer mill with a screen provided immediately after the extrusion type devolatilizer, if necessary, to obtain powder particles having a uniform particle size. .

The polycarbonate resin particles obtained from the outlet of the extrusion type devolatilizer are supplied to an extruder having one or more vacuum devolatilizing mechanisms, melt-kneaded and extruded, and pulverized to obtain a residual solvent. Can be obtained.

At this time, in the extruder, from the point downstream of the supply port and upstream of the final devolatilization hole, the amount of the obtained pellets, for example, the amount of the supplied resin, is selected so as not to adversely affect the quality, especially the hue and the molecular weight of the obtained pellets. It is also preferably employed to inject 0.1 to 2% by weight of water to promote the devolatilization of the solvent.

In a preferred embodiment, the polycarbonate resin powder obtained from the extrusion type devolatilizer outlet is supplied to a drier and dried before being supplied to the extruder. For example, a method of drying using a hot air circulation type dryer, a steam tube dryer, a hopper dryer, a tower dryer, or the like, or a method of drying in advance using these devices and further drying using a drying device such as a paddle dryer or a multi-fin dryer. preferable. In particular, the glass transition temperature (T
g) When drying the granular material at the above temperature, an apparatus that does not apply shear is preferable. These dryers may be used alone or in combination.

If necessary, any stabilizer, additive, filler or the like can be added to the thus obtained polycarbonate resin particles.

[0032]

EXAMPLES Examples of the present invention will be described below for further explanation. In the examples,% is% by weight. (1) The methylene chloride content was analyzed by analyzing the chlorine content with the following equipment, and converted to the amount of methylene chloride. (A) In the case of% order; the chlorine content is measured by a total organic halogen analyzer [TOX manufactured by Mitsubishi Kasei Co., Ltd.]
It was converted to the amount of methylene chloride. (A) In the case of ppm order: The chlorine content was measured by a fluorescent X-ray analyzer [manufactured by Rigaku Denki Kogyo] and converted to the amount of methylene chloride. (2) The specific viscosity was measured with an Ostwald viscometer at 20 ° C. using a solution of 0.7 g of a polycarbonate resin dissolved in 100 ml of methylene chloride.

Example 1 36 parts by weight of methylene chloride was placed in a dissolving tank equipped with a stirrer and a heating and pressurizing device, and a specific viscosity of 0.423 obtained from bisphenol A and phosgene by a conventional method.
12 parts by weight of the above polycarbonate resin was charged from the upper charging port under stirring, and after charging, the charging lid was tightened.
The solution was completely dissolved at 0 ° C. and 0.5 MPa to obtain a solution of a polycarbonate resin having a concentration of 25% methylene chloride.

The solution was supplied to an extrusion type devolatilizer having a jacket for heating the main body and an internal scraping device through a needle valve while flushing the solution. At normal pressure, the jacket temperature was set to 100 ° C., and the internal scraping device was set to 40 rpm. And the solvent in the polycarbonate resin was devolatilized. According to the observation from the sight glass, the solvent evaporates at the same time as the supply of the feed solution, and the inside of the system becomes paste-like on the shaft and the wall on the inlet side of the extrusion type devolatilizer, and is sequentially pushed downstream by the scraper. It was turned into a granular material. The temperature in the tank was 80 ° C. in the paste part and 100 ° C. in the powder part. The distilled methylene chloride was condensed and collected by a condenser attached to the outlet of the extrusion type devolatilizer. The polycarbonate resin powder was taken out from the extrusion type devolatilizer outlet. The concentration of methylene chloride contained in the polycarbonate resin particles was 3.1%.

Example 2 The polycarbonate resin particles obtained in Example 1 had a two-stage water addition function.
Extruder with devolatilization mechanism at two places (32 Φ, L / D4
2: Cylinder temperature 250 to 280 ° C, vent pressure 2.6
(× 10 ² to 40 × 10 ² Pa) at a rate of 30 kg / hour, and extruded while adding and injecting 0.3 kg / hour of water from two places. The obtained resin was cut to obtain pellets. The methylene chloride concentration in the pellets was 28
It was 0 ppm.

[Examples 3 and 4] The polycarbonate resin particles obtained in Example 1 were dried by a known drying method, and the methylene chloride concentration was 550 ppm and 2500.
ppm of a polycarbonate resin powder was obtained. This powder was supplied to an extruder (two-axis 32Φ, L / D28, cylinder temperature 270 ° C., vent pressure 5.3 × 10 ² Pa) at a rate of 30 kg / hour, and the obtained resin was cut to obtain a resin. A pellet was obtained. The methylene chloride concentrations in the pellets were 73 ppm and 340 ppm.

[Examples 5 and 6] The dried polycarbonate resin particles (concentration of methylene chloride; 550 ppm and 2500 ppm) obtained in Examples 3 and 4 were mixed with 2
An extruder having a function of adding step water and having a devolatilizing mechanism at two places (two shafts 32Φ, L / D42; cylinder temperature 250 to 28)
0 ° C, vent pressure of 2.6 × 10 ² to 40 × 10 ² Pa) at a rate of 30 kg / hour, and cutting the obtained resin while adding and injecting 0.3 kg / hour of water from two places. As a result, a pellet was obtained. The methylene chloride concentrations contained in the pellets were 5 ppm and 30 ppm.

[Comparative Example 1] In Example 1, the internal temperature of the extrusion type devolatilizer having an internal scraping function was raised to 150 ° C, and a 25% -concentration polycarbonate resin solution dissolved under heating and pressure was used. Except supplying to the extrusion type devolatilizer and devolatilizing, the procedure was the same as in Example 1. The polycarbonate resin in the extrusion type devolatilizer adhered to the internal scraper, and the resin taken out from the outlet was colored yellow and became a lump, and it was difficult to form a granular material.

Comparative Example 2 In Example 1, the internal temperature of the extrusion type devolatilizer having the internal scraping function was set to 38 ° C.
Example 1 was repeated except that a 25% concentration polycarbonate resin solution dissolved under heating and pressure was supplied to the extrusion type devolatilizer.
The procedure was performed in the same manner as described above. The polycarbonate resin in the extrusion type devolatilizer adheres to the internal scraper, and the resin taken out from the outlet is insufficiently devolatilized, and the resin becomes a lump and a ribbon, and it is difficult to form a granular material. Was. The concentration of methylene chloride contained in the obtained polycarbonate resin was 13%.

Comparative Example 3 Solution Temperature 30 ° C., Solution Concentration 2
Using a 0% methylene chloride solution of a polycarbonate resin, the mixture was fed to an extrusion devolatilizer having the same internal scraping function as in Example 1 at a jacket temperature of 120 ° C. The temperature in the extrusion devolatilizer fluctuates between 41 and 42 ° C., the form of the solution is maintained in the tank, and the resin mixed with the solution is taken out from the end take-out port to obtain a powder having a uniform particle size. Did not.

[0041]

According to the present invention, an extremely excellent polycarbonate resin powder having a small amount of residual solvent due to ordinary drying and having a uniform particle size and easy to handle can be stably produced by a simple method. It can be manufactured with good efficiency, and the industrial effects it produces are exceptional.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Tetsuya Fujita 1-2-2 Uchisaiwaicho, Chiyoda-ku, Tokyo Inside Teijin Chemicals Co., Ltd. (72) Inventor Masanobu Ezaki 1-2-2 Uchisaiwaicho, Chiyoda-ku, Tokyo Nippon Kasei Co., Ltd. (72) Inventor Masahiro Ishida 1-2-2 Uchisaiwaicho, Chiyoda-ku, Tokyo Teijin Chemical Co., Ltd. F-term (reference) 4F070 AA50 DA60 4F201 AA28 AC05 BA02 BC01 BC12 BC33 BL08 4J029 AA09 AB07 BB12A BB13A BD09A HC01 HC03 KE11 KH04 KH08

Claims (3)

[Claims] 1. A solution of an organic solvent of a polycarbonate resin,
Using an extrusion type devolatilizer having a function of moving the contents in one direction from the inlet side to the outlet side by heating and concentrating the solution at a temperature of 40 to 150 ° C. under pressure to a solution concentration of 23 to 50% by weight,
The above concentrated solution is flushed to the inlet side and supplied in the form of a paste, and the solvent is removed at normal pressure or reduced pressure at such a temperature as to maintain a solid state, and polycarbonate resin particles are obtained from the outlet side. Method for producing polycarbonate resin particles. 2. The method for producing polycarbonate resin particles according to claim 1, wherein the solvent is removed at a temperature not lower than the boiling point of the organic solvent and not higher than 145 ° C. 3. A method for producing polycarbonate resin pellets, wherein the polycarbonate resin granules obtained by melt-kneading and extruding the polycarbonate resin particles according to claim 1 by an extruder having a devolatilizing mechanism.