JPH07268107A - Method for producing polycarbonate resin powder - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a method of easily producing a polycarbonate resin powder having excellent drying properties, capable of extremely reducing the amount of residual organic solvent by ordinary drying, and having a uniform particle size. . [Structure] A solid polycarbonate resin containing an organic solvent and substantially free of water is continuously supplied to an extruder, finely pulverized to a diameter of 50 μm or less in the extruder, and extruded and cut without melting or melting. Or a pulverizing process, wherein 5% by weight or more of water is present in the polycarbonate resin during pulverization, and the amount of the organic solvent in the polycarbonate resin during pulverizing is 10 to 65% by weight. Method for producing resin powder.

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 powder particles. More specifically, the present invention relates to a method for easily producing a polycarbonate resin powder granule having excellent drying property, capable of reducing the amount of residual organic solvent by ordinary drying and having a uniform particle diameter.

[0002]

Polycarbonate resin is usually produced by a so-called solution method in which an alkaline aqueous solution of a dihydric phenol is reacted with phosgene in the presence of an organic solvent such as methylene chloride, and the organic solvent is removed from the obtained organic solvent solution of the polycarbonate resin. Then, the powder is granulated into a granule, and then subjected to a drying step. As a method for obtaining a powder or granular material by removing an organic solvent from an organic solvent solution of a polycarbonate resin, for example, a method of bringing an organic solvent solution of a polycarbonate resin into contact with hot water or steam to form flakes or powder (Japanese Patent Publication No. 36/36) -11231, Japanese Patent Publication No. 40-984
3 gazette, Japanese Examined Patent Publication 45-9875, and Japanese Examined Patent Publication 48-
No. 43752, Japanese Examined Patent Publication No. 54-122393), and a method of gelling by concentration and cooling to make powder (Japanese Examined Patent Publication No. 36-21033, Japanese Examined Patent Publication No. 38-224).
97, Japanese Patent Publication No. 40-12379, Japanese Patent Publication No. 4
No. 5-9875, Japanese Patent Publication No. 47-41421,
JP-A-51-41048) is known. However, a large amount of organic solvent still remains in the powder and granules (including flakes) obtained by these methods, and it is difficult to sufficiently remove this residual organic solvent by ordinary drying.

As a method of removing this residual organic solvent, a method of mixing with warm water having a boiling point of the residual organic solvent or higher and distilling it has been proposed. However, several hundred to several thousand ppm of organic solvent still remains in the powder and granules obtained by this method. In order to further reduce this residual organic solvent, it must be dried for a long time at high temperature or pelletized by an extruder with a vacuum vent, and still dozens to hundreds of ppm.
The organic solvent remains, and 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 containing little residual organic solvent, a non-solvent or a poor solvent is added to an organic solvent solution of the polycarbonate resin obtained by the reaction or an aqueous slurry of the polycarbonate resin powder containing the organic solvent remaining. Method of treatment, method of extracting organic solvent from polycarbonate resin powder granules in which organic solvent remains with a poor solvent (Japanese Patent Publication No. 55-1298, JP-A No. 63-
No. 278929, JP-A No. 64-6020) and the like have been proposed. In these methods, the organic solvent is sufficiently removed, but a large amount of the non-solvent and the poor solvent remains. The residual non-solvent and the poor solvent are sufficiently dried not only by ordinary drying but also by drying at high temperature for a long time. It is difficult to remove. Moreover, if the drying is strengthened in this way, the molecular weight of the product is lowered, the hue is deteriorated, and foreign substances are mixed. Further, as a method for producing polycarbonate resin granules having a large bulk density and a uniform particle size, a method in which an undried solid polycarbonate resin is extruded by an extruder provided with a die having a large number of pores (JP-A-62-62) No. 169605)
Is proposed. However, the polycarbonate resin particles obtained by this method have a problem that the amount of residual organic solvent varies.

[0005]

An object of the present invention is to provide a polycarbonate resin powder granule having excellent drying properties, capable of extremely reducing the amount of residual organic solvent by ordinary drying, and having a uniform particle size. It is to provide a manufacturing method.

The present inventor has conducted extensive studies as a system for removing the residual organic solvent from the polycarbonate resin particles or pellets that have already undergone the drying process, and as a result, supplies the polycarbonate resin particles or pellets to the extruder. Finely pulverized in the extruder in the presence of a specific amount of organic solvent and water to a specific diameter or less, and extruded without melting or dissolving and cutting or pulverizing is extremely excellent, and the amount of residual organic solvent is reduced by ordinary drying. It was found that it can be extremely reduced. Furthermore, by attaching a die having pores to the exit of the extruder,
The present invention has been completed by finding that a polycarbonate resin granule having an extremely excellent drying property and a uniform particle size can be obtained by cutting the strand-shaped polycarbonate resin extruded from the pores into a desired length.

[0007]

According to the present invention, a solid polycarbonate resin containing an organic solvent and substantially free of water is continuously fed to an extruder, and a diameter of 50 μm is set in the extruder.
It consists of finely pulverizing to m or less, and extruding without melting or dissolving to cut or pulverizing. At the time of finely pulverizing, 5% by weight or more of water is present with respect to the polycarbonate resin, and the organic matter in the polycarbonate resin during finely pulverizing is present. A method for producing a polycarbonate resin powder or granular material, characterized in that the amount of the solvent is 10 to 65% by weight based on the total weight of the organic solvent and the polycarbonate resin.

The organic solvent referred to in the present invention is mainly composed of at least one good solvent, and may be mixed with a poor solvent or a non-solvent. Good solvent, poor solvent and non-solvent as used herein are "polycarbonate" by WF CHRISTOPHER, DWFOX.
Solvents corresponding to “Good Solvent” and “Fair Solvent” in Table 3-1 on pages 32-33, 1962 are good solvents, “Poor Solvent”, “Very Poor Solvent”
And “Weak Solvent” are poor solvents, “Nons
Solvents that fall under “olvent” are non-solvents. Representative examples of good solvents are methylene chloride, tetrachloroethane, monochlorobenzene, etc., and representative examples of poor solvents are benzene, toluene, acetone, etc. Representative examples of the solvent include hexane, heptane, etc. Such poor solvent and non-solvent may be used alone or in combination of two or more kinds.

The polycarbonate resin referred to in the present invention is an aromatic polycarbonate resin obtained by reacting a dihydric phenol with a carbonate precursor. The dihydric phenol used here has the following general formula

[0010]

[Chemical 1]

[Wherein R is a substituted or unsubstituted alkylene group having 1 to 9 carbon atoms, an alkylidene group, a cycloalkylidene group, -S-, -SO-, -SO _2- , -O- or -C.
O-, X ₁ and X ₂ are an alkyl group having 1 to 3 carbon atoms or a halogen atom, and m and n are 0, 1 or 2. ] One type or two or more types of dihydric phenols selected from dihydric phenols and 4,4'-dihydroxydiphenyl represented by the formula, and particularly 2,2-bis (4-hydroxyphenyl) propane (commonly called bisphenol A) is It is preferably used. Examples of other dihydric phenols include bis (4-hydroxyphenyl) methane, 1,1-bis (4-hydroxyl) ethane, 1,1-bis (4-hydroxyl) cyclohexane, and 2,2-bis (4-). Hydroxy-3-methylphenyl) propane, bis (4-hydroxyphenyl) sulfone, bis (4-hydroxyphenyl) ether, 4,4′-dihydroxydiphenyl and the like, and further 2,2-bis (3,5) And halogenated bisphenols such as -dibromo-4-hydroxyphenyl) propane. Examples of the carbonate precursor include carbonyl halide, diaryl carbonate, haloformate and the like, and specific examples include phosgene, diphenyl carbonate and dihaloformate of dihydric phenol.

In producing a polycarbonate resin by reacting a dihydric phenol and a carbonate precursor,
If necessary, a catalyst, a molecular weight modifier, an antioxidant and the like may be used, and the polycarbonate resin may be, for example, a branched polycarbonate resin obtained by copolymerizing a trifunctional or higher polyfunctional aromatic compound, or two or more kinds. It may be a mixture of the above polycarbonate resins. The molecular weight of the polycarbonate resin does not need to be particularly limited. For example, in the case of a polycarbonate resin obtained by using bisphenol A as a dihydric phenol and phosgene as a carbonate precursor, a methylene chloride solution having a concentration of 0.7 g / dl is prepared at 20 ° C. It is preferable that the specific viscosity (η _SP ) measured by
Those of 0.19 to 1.50 are particularly preferable.

The polycarbonate resin used in the present invention is
A solid polycarbonate resin containing an organic solvent produced by any method, but containing substantially no water, that is, a saturated water content or less, which is usually a powder or pellets of a polycarbonate resin that has completed the drying step. Is.
In particular, a polycarbonate resin powder in which an organic solvent obtained from an organic solvent solution of a polycarbonate resin obtained by a solution method remains is preferable. The shape is not limited to powder or pellets, and may be, for example, powder, granules, flakes, lumps, or the like, and the size thereof may be any degree as long as there is no problem with the biting property of the extruder. There is no need to limit it at all, and if there is a problem with the biting property, pretreatment such as crushing may be performed. Hereinafter, such solid polycarbonate resin is referred to as polycarbonate resin powder.

The amount of organic solvent contained in the polycarbonate resin powder is not particularly limited, but if it is too large, it becomes difficult to handle the polycarbonate resin as powder, and if it is too small, the method of the present invention is adopted. Since it is not necessary, it is usually in the range of 50 ppm to 65% by weight. The amount of the organic solvent in the present invention is% by weight based on the total weight of the organic solvent and the polycarbonate resin.

In the present invention, the above-mentioned polycarbonate resin powder is supplied to an extruder, finely pulverized in the extruder, and extruded without melting or melting. In the fine pulverization stage in the extruder, the amount of organic solvent in the powder or granules needs to be 10 to 65% by weight. If the amount of the organic solvent is more than 65% by weight, it becomes difficult to pulverize, and if it is less than 10% by weight, the load of the extruder becomes large and the pulverization becomes difficult. It will be difficult to obtain. Particularly, the range of 15 to 45% by weight is preferable. When the amount of the organic solvent is not appropriate, it may be adjusted by adding or removing the organic solvent. When the amount of the organic solvent is small, an organic solvent, a solution of the polycarbonate resin in the organic solvent, or a polycarbonate resin powder having a large organic solvent content may be added in a predetermined amount. In particular, it is preferable to add an organic solvent solution of a polycarbonate resin obtained by a solution method because the granulation step of this solution can be omitted. In addition, it may be added to the polycarbonate resin powder or granular material supplied to the extruder, or may be added from the hopper or vent hole of the extruder. When the amount of organic solvent is large, a polycarbonate resin powder having a small organic solvent content may be added, and excess organic solvent may be removed by heating in advance, and the temperature of the extruder to be used was supplied. Excess organic solvent may be removed from the vent hole by adjusting so that the polycarbonate resin powder is not melted or dissolved. When adjusting the amount of the organic solvent, it is preferable to mix them uniformly.

Also, in the fine grinding stage in the extruder, 5% by weight
The above water needs to be present. This amount of water is 5% by weight
If the amount is smaller, the finely pulverized powders will adhere to each other, and it will be difficult to obtain the desired powder or granule having extremely excellent dryness. Also,
If this amount of water is too large, not only will the energy for drying the obtained powder and granules be large, but the strength of the powder and granules will be weakened and the powder and granules will be easily crushed by impact, so 120 weight % Or less is preferable. In particular, it is preferably 6 to 80% by weight because a powder or granule having extremely excellent dryness and hard to be crushed by impact is obtained. In order to allow a predetermined amount of water to be present, it is sufficient to add polycarbonate resin powder or granules containing water or a large amount of water.When adding, the vent holes of the extruder supplying the polycarbonate resin powder or granules, etc. It is preferable to add more. In addition, it is preferable to mix them uniformly for adjustment. The amount of water referred to in the present invention is% by weight with respect to the polycarbonate resin, and may be hereinafter referred to as water content.

In the pulverizing step, most of the polycarbonate resin powder particles (usually 90% by weight or more) have a diameter of 50 μm.
Or less, preferably 40 μm or less, particularly preferably 30 μm
Need to pulverize to m or less. Most of them have a diameter of 50
Unless finely pulverized to less than μm, it becomes difficult to obtain the desired polycarbonate resin powder granules having extremely excellent dryness.

When the finely pulverized polycarbonate resin is extruded, it is compressed without being melted or dissolved and extruded as an agglomerate of fine powder. If you melt or melt here,
It is not possible to obtain a desired polycarbonate resin powder having excellent dryness. In addition, when extruding, most of the water present in the pulverizing step should be left to prevent the fine powders from adhering to each other during agglomeration. Then, the extruded agglomerates of fine powder are crushed or cut and supplied to the organic solvent / drying step. The size of the polycarbonate resin finely pulverized in the extruder can be easily confirmed by folding the polycarbonate resin powder thus obtained into two or more pieces and enlarging the cross section thereof about 1000 times by an electron microscope.
Any device is used for crushing or cutting after extrusion.

When extruding the finely pulverized polycarbonate resin, a die having pores is attached to the exit of the extruder, and the extruded strand-shaped aggregated polycarbonate resin is cut into a desired length to obtain an excellent drying property. An excellent granular material having a uniform particle size can be obtained. The die may be either a pre-extrusion type that extrudes in the same direction as the extrusion axis or a horizontal extrusion type that extrudes at a right angle to the extrusion axis or in the axial direction, and the shape is not particularly limited, but from the machining surface of the hole A circular shape is common. From the viewpoint of extrusion capacity, drying efficiency, handleability, etc., the hole diameter of the die is preferably 0.1-5 mm, 0.5-3 mm.
It is preferable that the land has the same hole diameter and penetrates the die.
It may be a multi-stage communication hole having the same hole axis but different hole diameters. The ratio of the land length (L) to the hole diameter (D) is L / D of 1 to 1 from the viewpoint of strength of the obtained granular material, discharge pressure, strength of die, and the like.
It is preferably 0. When a die having multi-stage communication holes is used, the diameter of the holes and the land length may be such that extrusion is not hindered. Further, it may be a die having a taper. The strand-shaped polycarbonate resin extruded from the die can be cut by any method. A preferred example is a method of cutting by rotating a propeller attached so as to be parallel to the die surface. The length of the granular material can be adjusted by the mounting position of the propeller, the rotation speed, and the like.

The extruder used in the present invention may be of any type as long as it has a fine pulverizing function capable of finely pulverizing the supplied polycarbonate resin powder or granules to a diameter of 50 μm or less, preferably a type having a kneading function. Alternatively, it may be of a type having a drainage function. Examples thereof include a single-screw or multi-screw screw type extruder, a plunger type extruder, and an extruder having a mechanism such as an injection molding machine having an inner screw. Depending on the concentration of solvent in the polycarbonate resin powder and extrusion conditions, problems such as melting and melting of the polycarbonate resin may occur due to the rise in cylinder temperature and internal pressure.A jacket with a temperature control mechanism is provided to avoid such troubles. It is preferable to use a cylinder or screw. Further, a cylinder with a vent, a cylinder with a taper, and a screw with a compression section are also used.

The polycarbonate resin powder obtained is
It is possible to continuously and / or batchwise remove the organic solvent and dry it without the need to remove the liquid. The organic solvent removal / drying may be performed only by the drying step, and any device may be used alone or two or more types may be used in combination for drying. It may be dried after any organic solvent treatment such as a method of mixing with a liquid having a boiling point of the residual organic solvent or higher, a method of contacting with steam, etc., if necessary, depending on a poor solvent or a non-solvent. Extraction or addition treatment may be performed. When the amount of residual organic solvent in the obtained polycarbonate resin powder is large and the powder is likely to collapse, it is dried using a device that does not cause shearing, such as a hot air circulation dryer, a steam tube dryer, a pow heater, and a hopper dryer. Alternatively, it is preferable to previously dry using these devices and then dry using a drying device such as a paddle dryer or a multi-fin dryer. If desired, any stabilizer, additive, filler, etc. may be added to the polycarbonate resin powder thus obtained.

[0022]

EXAMPLES The present invention will be further described with reference to the following examples. In the examples,% is% by weight, methylene chloride content is% by weight with respect to the total weight of methylene chloride and polycarbonate resin, water content is% by weight with respect to polycarbonate resin, and evaluation is based on the following method. (1) Amount of methylene chloride: Chlorine content was determined by analysis with a total organic halogen analyzer [TOX manufactured by Mitsubishi Kasei Co., Ltd.]. (2) Amount of n-heptane: Gas chromatography [Co., Ltd.]
Hitachi Model 263] was used for the column packing using dioctyl sebacate. (3) Specific viscosity (η _SP ): Polycarbonate resin 0.7g
Was dissolved in 100 ml of methylene chloride at 20 ° C.
Measured with an Ostworld viscometer. (4) Average particle size (mm) and particle size distribution (n): Measured in accordance with the particle size measuring method described in Chapter 2, Section 2.4, "Granulation Handbook" edited by Japan Powder Industry Association. Rosin Ramlar n
Indicates the standard of particle size distribution, and the larger the value, the narrower the width of particle size distribution.

Example 1 (A) A 15% methylene chloride solution of a polycarbonate resin having a specific viscosity of 0.426, which was obtained from bisphenol A and phosgene by a conventional method, was put into a kneader charged with warm water kept at 42 ° C. To remove methylene chloride and then coarsely crush,
A water slurry having a powder / granule concentration of 25% and a liquid temperature of 38 ° C. was obtained. This slurry was crushed by a hammer mill with a screen having an opening of 5 mm, heated to 95 ° C. under stirring and held for 1 hour, and then centrifugally dehydrated to give a methylene chloride content of 0.8% and a water content of 13
% Powder was obtained. The obtained granular material was dried with a paddle dryer at 145 ° C. for 6 hours to give a residual methylene chloride content of 7
8 ppm, bulk density 0.62 g / ml, average particle size 0.51 mm,
A granular material having n of 1.02 and containing substantially no water was obtained. (B) Using a single screw extruder with a diameter of 40 mm, L / D of 9.25, no compression, a groove depth of 6 mm built in, and a cylinder equipped with a temperature control jacket, the exit diameter of the extruder was 2 mm. A die with 82 holes with a land length of 5 mm was installed at the front of the die at intervals of 4 mm (1
Single blade propeller) and jacket temperature of 15 ℃,
Screw rotation speed is 20 rpm, cutting machine rotation speed is 80 rpm
Set to. The polycarbonate resin powder obtained in the above (A) is continuously fed to the extruder, and at the same time, water and a methylene chloride solution of the polycarbonate resin used in Example 1 (A) are continuously supplied from a vent provided in the center of the cylinder. Injected. The supply amount of powder and granules is 1.5 kg / hour, the supply amount of water is 0.3 kg / hour, and the supply amount of methylene chloride solution is 0.8 kg / hour.
The extrusion rate was 1.8 kg / hour. At this time, the amount of resin was 1.6 kg / hour, the amount of water was 18.5%, and the amount of methylene chloride was 29.6%. The granules were finely pulverized in an extruder and extruded to obtain granules having a water content of 17% and a methylene chloride content of 25%. The obtained granules were heated with a hot air circulation dryer to 14
After drying at 5 ° C for 6 hours, the amount of residual methylene chloride is 7.5 ppm,
Bulk densities of 0.60 g / ml and about 95% passed through 8 mesh, and granules remained in all 14 mesh were obtained. When the folded surface of this granular material was magnified 1000 times with an electron microscope, it was confirmed to be an aggregate of fine powder having a diameter of 2 to 20 μm.

[Example 2] 15 parts of methylene chloride was added to 30 parts of the polycarbonate resin powder obtained in Example 1 (A), and the mixture was thoroughly kneaded to obtain a powder obtained in the extruder of Example 1. While continuously charging the hopper at 2.5 kg / hour, water was continuously injected at 0.4 kg / hour from a vent provided in the center of the cylinder. The amount of water at this time is 24%. The granules were finely pulverized in an extruder and extruded to obtain granules having a water content of 22% and a methylene chloride content of 30%. The obtained granules were dried at 145 ° C. for 6 hours with a hot air circulation dryer to obtain a residual methylene chloride content of 7.0 ppm and a bulk density of 0.59 g / ml.
About 95% of the particles passed through 8 mesh, and granules remained in all 14 mesh were obtained. When the broken surface of this granular material was magnified 1000 times with an electron microscope, the diameter was 2 to 20 μm.
It was confirmed to be an aggregate of fine powder of m 2.

[Example 3] Polycarbonate resin granules having a water content of 13% and a methylene chloride content of 22% were obtained in the same manner as in Example 1 except that a compression part having a compression ratio of 1.66 was provided in the front part of the screw. It was The granules were dried at 145 ° C. for 6 hours by a hot air circulation dryer, the residual methylene chloride amount was 7.0 ppm, the bulk density was 0.59 g / ml, and about 95% passed through 8 mesh, and all remained on 14 mesh. A granular body was obtained. The folded surface of this granular material is examined by an electron microscope to 1000
When it was magnified twice, it was confirmed to be an aggregate of fine powder having a diameter of 2 to 20 μm.

[Embodiment 4] At the exit, the hole diameter is 2 mm and the land length is 6
2. Provide a die with 120 mm holes, and in front of the die 3.
Cutting machine at intervals of 5 mm (50 mm long single blade propeller)
, A twin-screw extruder with a diameter of 30 mm and a L / D of 25 (jack made by Ikegai Iron Works P
CM-30) was used. The jacket temperature was set to 15 ° C., the screw rotation speed was set to 80 rpm, and the cutting machine rotation speed was set to 200 rpm. The polycarbonate resin powder obtained in Example 1 (A) was continuously fed to the extruder, and at the same time water and The methylene chloride solution of the polycarbonate resin used in Example 1 (A) was continuously injected through a vent provided in the center of the cylinder. The supply amount of powder and granules is 16 kg / hour, the supply amount of water is 8.8 kg / hour, and the supply amount of methylene chloride solution is 11.2 kg.
/ H, the extrusion rate was 34.3 kg / h. At this time, the amount of water is 50% and the amount of methylene chloride is 35%. The granules were finely pulverized in an extruder and extruded to obtain granules having a water content of 40% and a methylene chloride content of 32%. The obtained granules were dried at 145 ° C. for 6 hours with a hot air circulation dryer to obtain a residual methylene chloride amount of 4.5 ppm, a bulk density of 0.59 g / ml, and an amount of about 9%.
5% of which passed through 8 mesh, and granules remained in all 14 mesh were obtained. When the folded surface of this granular material was magnified 1000 times with an electron microscope, it was confirmed to be an aggregate of fine powder having a diameter of 2 to 30 μm.

[Example 5] Except for removing the die and the cutter, finely pulverized and extruded in an extruder in the same manner as in Example 4, and the obtained agglomerates were pulverized by a hammer mill with a screen having an opening of 5 mm. A polycarbonate resin powder having a water content of 45% and a methylene chloride content of 35% was obtained. The granules were dried at 145 ° C. for 6 hours by a hot air circulation dryer to obtain a residual methylene chloride content of 3.6 ppm, a bulk density of 0.63 g / ml, an average particle diameter of 0.83 mm, and an n of 1.43. Granules were obtained. When the folded surface of the powder and granules was magnified 1000 times with an electron microscope, it was confirmed that the powder and granules were aggregates of fine powder having a diameter of 2 to 20 μm.

Example 6 A methylene chloride solution of the polycarbonate resin used in Example 1 (A) was stirred at 45 ° C.
Was added dropwise to the warm water held in Table 1 and pulverized with a wet pulverizer, and then methylene chloride was removed while circulating in a stirring tank to obtain a water slurry having a concentration of 20% of particles. To this slurry, 30% of n-heptane with respect to the polycarbonate resin was added with stirring and mixed for 20 minutes to obtain a methylene chloride content of 15
% Powder / granular water slurry, heated to 95 ° C. with stirring and held for 1 hour, and then centrifugally dehydrated to give a methylene chloride content of 0.
A powder and granules having 5% and a water content of 11% were obtained. The obtained powder and granules were dried by a paddle dryer at 145 ° C. for 6 hours to give a residual methylene chloride content of 5 ppm and an n-heptane content of 700 ppm.
A powdery material having a bulk density of 0.62 g / ml, an average particle size of 0.63 mm and an n of 1.86 was obtained substantially free of water. The powder and granules were continuously fed to the hopper of the same twin-screw extruder as in Example 4, and at the same time, water and a methylene chloride solution of the polycarbonate resin used in Example 1 (A) were added to the solution. A solution in which 10% n-heptane was added and mixed was continuously injected from a vent provided in the center of the cylinder. The amount of powder supplied is 37.5 kg / hour, and the amount of water supplied is 3
The supply rate of the methylene chloride solution containing 2.5 kg / hour and n-heptane was 20.5 kg / hour. At this time, the amount of resin was 40.3 kg / hour, the amount of water was 80.6%, and the amount of methylene chloride was 28.2%. Finely crush the powder in the extruder,
Extruded to obtain granules having a water content of 50% and a methylene chloride content of 25%. The obtained granular material was dried at 120 ° C. for 1 hour with a hot air circulation dryer, and then with a paddle dryer.
Drying at 45 ℃ for 6 hours, residual methylene chloride content 0.6ppm
, N-heptane amount 70 ppm, bulk density 0.60 g / ml,
About 93% of the particles passed through 6 mesh, and all of the granules remained in 8 mesh were obtained. When the broken surface of this granular material was magnified 1000 times with an electron microscope, the diameter was 2 to 20 μm.
It was confirmed to be an aggregate of the fine powder of

Comparative Example 1 Polycarbonate resin granules obtained in Example 1 (A) with an amount of residual methylene chloride of 78 ppm, a bulk density of 0.62 g / ml, an average particle size of 0.51 mm and n of 1.02. Was further dried with a paddle dryer at 145 ° C. for 6 hours to give a residual methylene chloride content of 51 ppm and a bulk density of 0.62.
A granular material having g / ml, an average particle size of 0.49 mm and n of 1.00 was obtained. When the powder and granules were magnified 1000 times by an electron microscope, it was confirmed that the powder was a polycarbonate resin powder having a particle diameter of almost 70 to 3000 μm and not an agglomerate of fine powder.

[Comparative Example 2] All were obtained in the same manner as in Example 1 except that the amount of water supplied in Example 1 (B) was changed to 0.03 kg / hour (the amount of water at this time was 2%). After drying, the polycarbonate resin granules had a residual methylene chloride content of 2500 ppm and a bulk density of 0.61 g / ml. When the granules were magnified 1000 times with an electron microscope, most of them were continuous layers, and the fine powders were mutually It was confirmed that they were in close contact.

[Comparative Example 3] The dried polycarbonate resin granules obtained in the same manner as in Example 1 except that water was not added in Example 1 (B) were 0.9% residual methylene chloride. The bulk density was 0.63 g / ml, and when this granular material was magnified 1000 times by an electron microscope, it was confirmed that it was a continuous layer on the entire surface and was not an aggregate of fine powder.

[0032]

According to the present invention, the drying property is extremely excellent,
Polycarbonate resin granules with very little residual solvent can be obtained by ordinary drying, and the resulting polycarbonate resin granules have a uniform particle size and are extremely easy to handle, and the industrial effects they produce are exceptional. Is.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Yoshifumi Ikemura 1-6-21 Nishishinbashi, Minato-ku, Tokyo Within Teijin Kasei (72) Inventor Katsuhiro Kona 1-6-21 Nishishinbashi, Minato-ku, Tokyo No. Teijin Kasei Co., Ltd.

Claims (2)

[Claims] 1. A solid polycarbonate resin containing an organic solvent and substantially free of water is continuously supplied to an extruder, finely pulverized to a diameter of 50 μm or less in the extruder, and extruded without melting or dissolving. It consists of cutting or crushing by crushing, and at the time of fine pulverization, 5% by weight or more of water is present relative to the polycarbonate resin, and the amount of organic solvent in the polycarbonate resin during fine pulverization is based on the total weight of the organic solvent and the polycarbonate resin. 10 to 65% by weight of the polycarbonate resin powder granules. 2. The polycarbonate according to claim 1, wherein the step of extruding the polycarbonate resin from an extruder and cutting or pulverizing the polycarbonate resin is a step of extruding the finely pulverized polycarbonate resin through the pores of a die attached to the exit of the extruder and cutting it. Method for producing resin powder.