JPH07268106A - Production of polycarbonate resin powdery or granular material - Google Patents

Abstract

PURPOSE:To provide a method for readily producing a polycarbonate resin powdery or granular material, containing an extremely small amount of a residual organic solvent, hardly being crushed by impact and having a uniform particle diameter. CONSTITUTION:This method for producing a polycarbonate resin powdery or a granular material comprises continuously feeding a solid polycarbonate resin having an organic solvent and water to an extruder, finely pulverizing the polycarbonate resin to particles having <=50mum diameter in the extruder, extruding the particles without melting or dissolving the particles and cutting or pulverizing the resultant extrudate. The water content in the polycarbonate resin fed to the extruder is regulated to 5-30wt.% and the content of the organic solvent in the polycarbonate resin in fine pulverization is regulated to 10-65wt.%.

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 of easily producing a polycarbonate resin powder having a very small amount of residual organic solvent, being hardly crushed by impact, and having a uniform particle size.

[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 having less residual organic solvent, a method of adding a non-solvent or a poor solvent to an aqueous solvent solution of the polycarbonate resin powder or an organic solvent solution of the polycarbonate resin obtained by the reaction or an organic solvent solution of the polycarbonate resin obtained by the reaction. , A method of extracting an organic solvent with a poor solvent from a polycarbonate resin powdery material in which the organic solvent remains (Japanese Patent Publication No.
-1298, JP-A-63-278929,
JP-A-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 enhanced in this way, the molecular weight of the product is lowered, the hue is deteriorated,
Foreign matter will be mixed in. Further, as a method for producing polycarbonate resin granules having a large bulk density and a uniform particle size, a method of extruding an undried solid polycarbonate resin with an extruder provided with a die having a large number of pores (Japanese Patent Application Laid-Open No. 62-62). No. 169605) has been proposed. However, the polycarbonate resin granules obtained by this method are easily crushed by impact, and there are problems that fine powder is generated and the handling property thereof is deteriorated, drying energy is increased, and the amount of residual organic solvent varies. .

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for easily producing a polycarbonate resin powder which has a very small amount of residual organic solvent, is hard to be crushed by impact, and has a uniform particle size. .

As a result of earnest studies aimed at achieving the above object, the present inventor has made a specific amount of water in a polycarbonate resin powdery granule having an organic solvent and water, and continuously supplies this powdery granule to an extruder. , Finely pulverized in an extruder in the presence of a specific amount of an organic solvent 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 can be reduced by ordinary drying. It has been found that a polycarbonate resin powder can be obtained which can be extremely reduced and is not easily crushed by impact. Furthermore, by attaching a die having pores to the exit of the extruder and cutting the strand-shaped polycarbonate resin extruded from these pores to a desired length, the drying property is extremely excellent, and it is difficult to be crushed by impact and has a particle size. The present invention has been completed by finding that a polycarbonate resin granule having a uniform distribution can be obtained.

[0006]

According to the present invention, a solid polycarbonate resin containing an organic solvent and water is continuously supplied to an extruder and finely ground to a diameter of 50 μm or less in the extruder,
It consists of extrusion and cutting or crushing without melting or dissolving, and the amount of water contained in the polycarbonate resin supplied to the extruder is 5 to 30 with respect to the polycarbonate resin.
A method for producing a polycarbonate resin powder, wherein the content of the organic solvent in the polycarbonate resin at the time of fine pulverization 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

[0009]

[Chemical 1]

[In the formula, 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-). Examples thereof include hydroxy-3-methylphenyl) propane, bis (4-hydroxyphenyl) sulfone, bis (4-hydroxyphenyl) ether, 4,4-dihydroxydiphenyl, and further 2,2-bis (3,5- Dibromo-
Examples thereof include halogenated bisphenols such as 4-hydroxyphenyl) propane. As the carbonate precursor, carbonyl halide, diaryl carbonate,
Examples thereof include haloformates and the like, and specific examples include phosgene, diphenyl carbonate, dihaloformates of dihydric phenols, and the like.

In producing a polycarbonate resin by reacting a dihydric phenol with 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, and may be a polycarbonate resin produced by any method, and its shape may be arbitrary such as powder, granules, flakes, and lumps. Preference is given to polycarbonate resin granules in which the organic solvent obtained in the step of granulating the organic solvent solution of the polycarbonate resin obtained by the solution method remains. There is no need to limit the size as long as there is no problem with the biting property of the extruder, 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 the 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, a polycarbonate resin powder having a specific amount of water is supplied to the extruder. If this amount of water is too small, it becomes difficult to obtain a powder and granules having extremely excellent target drying properties because the powders finely pulverized in the extruder described below are in close contact with each other, and if the amount of water is too large, Since the strength becomes weak and it is easily broken by impact, it should be 5 to 30% by weight, preferably 5 to 25% by weight. If the amount of water is not appropriate, it may be adjusted by adding or removing water or adding a polycarbonate resin powder. When the water content is large, for example, a polycarbonate resin powder having a low water content may be added or a dehydration treatment may be performed, and a dehydration treatment using a centrifuge or the like is particularly preferable.
When the amount of water is small, a predetermined amount of water or a polycarbonate resin powder having a high water content may be added. In adjusting the amount of water, it is preferable to mix them uniformly. 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.

The polycarbonate resin powder particles supplied to the extruder are finely pulverized in the extruder and then extruded without melting or melting. At this finely pulverizing stage, it is necessary to make the amount of the organic solvent in the granular material appropriate. If the amount of the organic solvent is too large, it becomes difficult to be finely pulverized, and if it is too small, the load of the extruder becomes large and it becomes difficult to finely pulverize, and it becomes difficult to obtain the target granular material having extremely excellent drying property.
The amount of organic solvent in the granules in this finely pulverizing step should be 10 to
It should be 65% by weight, with a range of 15-45% by weight being preferred. 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, an organic solvent solution of the polycarbonate resin, or a polycarbonate resin powder having a large organic solvent content may be added in an amount to give 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. When adding, it may be added to the polycarbonate resin powder or granular material supplied to the extruder, or may be added through a vent hole or the like 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.
Further, as described above, 5 to 30% by weight, preferably 5 to 25% by weight of water needs to be present in the finely pulverizing step, which is usually covered by the water contained in the polycarbonate resin powder granules to be supplied. Depending on the situation, water may be further added through the vent hole of the extruder.

In the finely 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 the finely pulverized polycarbonate resin is extruded, 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 which is not easily crushed by impact and has 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. The hole structure of the die is preferably 0.1 to 5 mm, more preferably 0.5 to 3 mm, from the viewpoints of extrusion capacity, drying efficiency, handleability, etc., and even if 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. From the standpoints of strength of the obtained granular material, discharge pressure, strength of die, etc., the ratio of land length (L) to hole diameter (D) is preferably L / D of 1 to 10.
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 particles 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. For the liquid removal function, a punch plate or slit for liquid removal may be provided on the whole or part of the cylinder,
A drainage mechanism may be provided on the ground side. Most of the excess water contained in the polycarbonate resin granules, such as separated water and water adhering or contained therein, is separated on the opposite side of the die, or separated by a punch plate, a slit or the like. The openings of the gland and the punch plate, the clearances of the slits, and the like are not particularly limited, and may be appropriately selected depending on the particle diameter of the polycarbonate resin powder particles supplied, the amount of water contained in the polycarbonate resin powder particles, and the like.

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. In addition, the polycarbonate resin powder thus obtained has an optional stabilizer,
Additives and fillers may be added.

[0021]

EXAMPLES The present invention will be further described with reference to the following examples. In the examples, parts and% are parts by weight and% 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 performed by the following method. It was (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.
Was 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. (5) Strength: 20 kg of the polycarbonate resin powder granules were stored in a paper bag and a drop test was performed 20 times from a height of 2 m, and the fracture state of the obtained polycarbonate resin powder granules was measured by the method of (4). .

[Example 1] (A) A 15% methylene chloride solution of a polycarbonate resin having a specific viscosity of 0.426 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 and granular material concentration of 50% and a liquid temperature of 38 ° C. was obtained. This slurry was dehydrated by a centrifuge to obtain a granular material having a methylene chloride content of 25% and a water content of 13%. (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. Methylene chloride content obtained in (A) above 25
%, Water content 13% powder and granules are continuously fed to the extruder,
It was pulverized in an extruder and extruded to obtain a granular material. The extrusion rate was 1.8 kg / hour, the obtained granules had a water content of 11%,
The methylene chloride content was 20%. The granules were dried at 145 ° C. for 6 hours by a hot air circulation type dryer, the residual methylene chloride amount was 4.5 ppm, the bulk density was 0.58 g / ml, all of which passed through 8 mesh, and about 95% remained on 14 mesh. A granular body was obtained. After the strength test, all the granules passed through 8 mesh, and about 92% remained in 14 mesh. 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] A specific viscosity of 0.405 obtained by a conventional method from bisphenol A and phosgene, and a water content of 0.2.
300 parts of polycarbonate resin powder with 1% and residual methylene chloride content of 0.45%, 150 parts of methylene chloride and 6 parts of water
5 parts were added and sufficiently kneaded to obtain a granular material, which was continuously supplied to the extruder used in Example 1, finely pulverized in the extruder, and extruded to obtain a water content of 17% and a methylene chloride content of 30. % Granulate was obtained. This granular material was heated to 145 by a hot air circulation dryer.
After drying for 6 hours at ℃, residual methylene chloride amount 4.8ppm, bulk density 0.60g / ml, all passed 8 mesh,
Granules were obtained which remained about 95% on the mesh. After the strength test, all the granules passed through 8 mesh, and about 93% remained on 14 mesh. 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

[Example 3] Polycarbonate resin granules having a water content of 8% and a methylene chloride content of 18% 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 3.7 ppm, the bulk density was 0.59 g / ml, all of which passed through 8 mesh, and about 95% remained on 14 mesh. A granular body was obtained. After the strength test, all the granules passed through 8 mesh,
Approximately 93% remained on 14 mesh. 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 4] An agglomerate obtained in the same manner as in Example 3 except that the die and the cutting machine were removed, was crushed by a hammer mill with a screen having 5 mm openings to have a water content of 9% and a methylene chloride content. 19% polycarbonate resin powder was obtained. The powder and granules were dried at 145 ° C for 6 hours with a hot air circulation dryer.
After drying for an hour, a powdery granule having an amount of residual methylene chloride of 2.1 ppm, a bulk density of 0.63 g / ml, an average particle size of 0.83 mm and n of 1.43 was obtained. The average particle size of the powder after the strength test is 0.80
mm and n were 1.37. When the broken surface of this granular material was magnified 1000 times with an electron microscope, the diameter was 2 to 2.
It was confirmed to be an aggregate of fine powder of 0 μm.

Example 5 The water slurry of the polycarbonate resin powder granules obtained in Example 1 (A) was heated with stirring to give 6
The temperature was raised to 5 ° C., the mixture was heated and stirred for 30 minutes, and then dehydrated by a centrifuge to obtain a granular material having a methylene chloride content of 7% and a water content of 8%. The powder and granules were fed to the same extruder as in Example 1, and the vent hole provided in the center of the cylinder was used to obtain Example 1.
A methylene chloride solution of the polycarbonate resin used in (A) was continuously injected. The supply amount of powder is 0.98 kg /
At this time, the injection amount of the methylene chloride solution was 0.37 kg / hour. At this time, the amount of resin is 0.91 kg / hour, and the amount of water is 7.5.
%, And the amount of methylene chloride becomes 29.5%. The obtained granular material had a water content of 6.5% and a methylene chloride content of 26%. The granules were dried at 145 ° C. for 6 hours with a hot air circulation dryer.
After drying for an hour, the amount of residual methylene chloride was 5.1 ppm, the bulk density was 0.59 g / ml, all of which passed through 8 mesh, and about 95% of the granules remained on 14 mesh. After the strength test, all the granules passed through 8 mesh, and about 9 mesh per 14 mesh.
2% remained. 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 6 A methylene chloride solution of the polycarbonate resin used in Example 1 (A) was stirred at 45 ° C.
After dripping into the warm water held in and processing with a wet pulverizer,
While circulating in a stirring tank, methylene chloride was removed to obtain a water slurry having a particle concentration of 20%, which was dehydrated by a centrifuge to obtain a powder having a methylene chloride concentration of 20% and a water content of 22%. Use this powder and granules to make holes with a hole diameter of 3 mm and a land length of 5 mm.
Change to a die that has one, the screw rotation speed is 40 rpm,
Cutting machine rotation speed is 120 rpm, distance between die and cutting machine is 6 mm
The same extruder as in Example 1 was continuously supplied, finely pulverized and extruded except that the setting was made. The extrusion rate was 4.5 kg / hour, and the obtained granules had a water content of 15% and a methylene chloride content of 13%. The obtained granules were dried at 120 ° C. for 1 hour by a hot air circulation dryer, and then dried at 145 ° C. for 6 hours by a paddle dryer to obtain a residual methylene chloride content of 8.9 ppm and a bulk density of 0.58 g / ml, 6 All the particles passed through the mesh, and about 93% of granules remained in 8 mesh. After the strength test, all the granules passed through 6 mesh,
About 91% remained on the 8 mesh. 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 7] To the water slurry of the polycarbonate resin powder obtained in Example 1 (A), 30% of n-heptane was added with stirring, and mixed for 20 minutes. A slurry having a methylene chloride content of 18% was formed, and the slurry was dehydrated by a centrifuge to a water content of 7%, and then continuously fed to the extruder in the same manner as in Example 1, and finely pulverized in the extruder. Then, it was extruded to obtain granules having a water content of 5% and a methylene chloride content of 13%. The obtained granules were dried for 6 hours at 145 ° C. by a hot air circulation dryer, and the residual methylene chloride amount was 0.7 ppm, the residual n-heptane amount was 80 ppm, the bulk density was 0.60 g / ml, and all of them passed through 8 mesh. Then, about 95% of the granules remaining in 14 mesh were obtained. After the strength test, all the granules passed through 8 mesh, and about 9 mesh per 14 mesh.
2% remained. 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.

[Embodiment 8] At the outlet, a hole diameter of 2 mm and a land length of 6
2. Provide a die with 120 mm holes, and in front of the die 3.
A twin-screw extruder with a diameter of 30 mm and L / D of 25 (a PCM-made by Ikegai Tekko KK 30) was used. Jacket temperature 15
℃, screw rotation speed 80 rpm, cutting machine rotation speed 20
The polycarbonate resin powder having a methylene chloride content of 25% and a water content of 13% obtained in Example 1 (A) was supplied to an extruder, finely pulverized in the extruder and extruded.
The extrusion rate was 45 kg / hour, and the obtained granules had a water content of 5
%, And the methylene chloride content was 18%. The granules were dried at 145 ° C. for 6 hours with a hot air circulation dryer to obtain a residual methylene chloride content of 2.5 ppm and a bulk density of 0.59 g / ml.
All the particles passed through 8 mesh, and about 95% of the granules remained in 14 mesh. After the strength test, all the granules passed through 8 mesh, and about 92% remained in 14 mesh.
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 9] A solution prepared by adding 1.5% of n-heptane to a 15% methylene chloride solution of a polycarbonate resin having a specific viscosity of 0.426 obtained by a conventional method from bisphenol A and phosgene was used. Example 1
The granules having a methylene chloride content of 15% and a water content of 9% obtained in the same manner as in (A) were continuously supplied to an extruder under the same conditions as in Example 8, finely pulverized in the extruder, and extruded. did. The obtained granular material had a water content of 6% and a methylene chloride content of 13%. The obtained granules were dried at 145 ° C. for 6 hours with a hot air drier to obtain a residual methylene chloride content of 0.8 ppm, a residual n-heptane content of 90 ppm, a bulk density of 0.57 g / ml, and all of which passed 8 mesh, Granules having about 95% remaining on 14 mesh were obtained. After the strength test, all the granules passed through 8 mesh, and about 92% remained in 14 mesh. 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.

[Comparative Example 1] An aqueous slurry of the polycarbonate resin powder granules obtained in Example 1 (A) was crushed by a hammer mill with a screen having an opening of 5 mm and dehydrated by a centrifuge to give a methylene chloride content. 20%, water content 13%
To obtain a granular material. The powder and granules were dried at 145 ° C. for 6 hours by a hot air circulation dryer, and the residual methylene chloride content was 69 ppm.
A powdery material having a bulk density of 0.61 g / ml, an average particle size of 0.54 mm and n of 1.02 was obtained. The granular material after the strength test was hardly crushed and could not be broken. When it was magnified 1000 times with an electron microscope, the particle size was almost 70 to 3
It was confirmed that the particles were 000 μm in size and were not aggregates of fine powder.

[Comparative Example 2] Polycarbonate resin powder particles having a methylene chloride content of 7% and a water content of 8% obtained in Example 5 were supplied to an extruder in the same manner as in Example 1, but discharge was difficult. .

[Comparative Example 3] Concentration of polycarbonate resin powder particles before dehydration in Example 1 (A) was 50%, and liquid temperature was 38.
C water slurry was continuously fed to the extruder of Example 1,
It was pulverized in an extruder and extruded to obtain a granular material. The obtained granules had a water content of 18%, a methylene chloride content of 20% and an extrusion rate of 1.5 kg / hour. The obtained granules were dried for 6 hours at 145 ° C. by a hot air circulation type dryer, the residual methylene chloride amount was 4.5 ppm, the bulk density was 0.58 g / ml, all of which passed through 8 mesh, and about 14% of 14 mesh was obtained. A residual granulate was obtained. After the strength test, all the granules passed through 8 mesh, and about 84% remained in 14 mesh. 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.

[0034]

EFFECT OF THE INVENTION According to the method of the present invention, a polycarbonate resin powder having extremely excellent drying property and an extremely small residual solvent can be obtained by ordinary drying, and the obtained polycarbonate resin powder has a uniform particle size. In addition, it is extremely easy to handle because it is not crushed during transportation. Further, if the method of the present invention is applied to a polycarbonate resin powder product having a large amount of residual solvent, the residual solvent can be extremely reduced, the particle size can be made uniform, and it is also difficult to crush, etc. 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 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 melting to cut or pulverize. The amount of water contained in the polycarbonate resin supplied to the extruder is 5 to 30% by weight with respect to the polycarbonate resin, and the amount of the organic solvent in the polycarbonate resin during fine pulverization is 10 with respect to the total weight of the organic solvent and the polycarbonate resin. A method for producing a polycarbonate resin powder or granular material, characterized in that the content is ˜65% by weight. 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.