JPH07330890A - Method for producing polycarbonate resin powder - Google Patents

Abstract

PURPOSE:To easily obtain polycarbonate resin granules with very low residual solvent content and uniform size. CONSTITUTION:A solid polycarbonate resin slurry containing 50ppm to 10wt.% of an organic solvent is continuolusly fed into an extruder inside which the resin is pulverized and then extruded without melting or dissolution. During the pulverization, >=5wt.% of water is made to exist in the resin and the organic solvent content of the resin is adjusted to 10-65wt.%. After extruded, the resin is cut or ground, thus obtaining the objective polycarbonate resin granules.

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, it relates to a method for easily producing a polycarbonate resin powder having a very small amount of residual organic solvent and 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 Patent Publication No. 54-122393), and a method of gelling by concentration or cooling to make powder (Japanese Patent Publication No. 36-21033, Japanese 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]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for easily producing a polycarbonate resin powder having a very small residual organic solvent and a uniform particle size.

As a result of earnest studies aimed at achieving the above object, the present inventor supplied a slurry of a solid polycarbonate resin containing an organic solvent to an extruder, and in the presence of a specific amount of the organic solvent and water in the extruder. It was found that if finely pulverized to a specific diameter or less, then extruded without melting or dissolving and then cut or pulverized, the drying property is extremely excellent, and a polycarbonate resin powder or granular material having an extremely small amount of residual organic solvent can be obtained by ordinary drying. It was 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 polycarbonate resin granules with extremely excellent dryness and uniform particle size The inventors have found that a body can be obtained and completed the present invention.

[0007]

According to the present invention, an organic solvent is used.
A solid polycarbonate resin slurry containing 0 ppm to 10% by weight 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 be cut or pulverized. At least 5% by weight of water is present with respect to the polycarbonate resin during pulverization, and the amount of organic solvent in the polycarbonate resin during pulverization is 10 to 65% by weight based on the total weight of the organic solvent and the polycarbonate resin. And a method for producing a polycarbonate resin powder or granular material.

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-, -SO2-, -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. Other dihydric phenols include, for example, bis (4-hydroxyphenyl) methane, 1,1-bis (4-hydroxyphenyl) ethane, 1,1-bis (4
-Hydroxyphenyl) cyclohexane, 2,2-bis (4-hydroxy-3-methylphenyl) propane, bis (4-hydroxyphenyl) sulfone, bis (4-hydroxyphenyl) ether, 4,4-dihydroxydiphenyl and the like. Furthermore, 2,2-bis (3,5-
Examples thereof include 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.

When the polycarbonate resin is produced by reacting the above dihydric phenol with the carbonate precursor, a catalyst, a molecular weight modifier, an antioxidant, etc. may be used, if necessary. It may be a branched polycarbonate resin obtained by copolymerizing a trifunctional or higher polyfunctional aromatic compound or a mixture of two or more kinds of polycarbonate resins. The molecular weight of the polycarbonate resin is not particularly limited. For example, in the case of a polycarbonate resin obtained by using bisphenol A as the dihydric phenol and phosgene as the carbonate precursor,
A methylene chloride solution having a concentration of 0.7 g / dl and a specific viscosity (η SP) measured at 20 ° C. of 3.00 or less are preferable, and 0.19 to 1.50 are particularly preferable.

The polycarbonate resin used in the present invention is
It is a solid polycarbonate resin containing an organic solvent produced by an arbitrary method, and its shape may be arbitrary such as powder, granules, pellets, flakes, and lumps. 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. In addition, the amount of water in the polycarbonate resin powder is 47
It is more than weight%. The amount of water mentioned here is% by weight with respect to the polycarbonate resin. When the amount of water is 47% by weight or more, the polycarbonate resin powder particles can be easily transported and easily supplied to the extruder. When the amount of water is small, treatment such as addition of water may be performed.

If the amount of the organic solvent contained in the polycarbonate resin powder is too large, it becomes difficult to adjust the amount of the organic solvent at the time of fine pulverization, and if it is too small, the method of the present invention does not have to be adopted, so that it is 50 ppm. It is in the range of 10% 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. Especially 15 to 4
A range of 5% by weight is 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, a polycarbonate resin solution, or a polycarbonate resin powder containing a large amount of the organic solvent may be added in a predetermined amount. In particular, it is preferable to add a polycarbonate resin solution obtained by a solution method because the granulation step of this solution can be omitted.
When adding, add 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. If the amount of water is not appropriate, it may be adjusted by adding or removing water or adding polycarbonate resin powder or the like. When the amount of water is large, for example, polycarbonate resin powder or granular material with a small amount of water is added, dehydration treatment is performed with a centrifuge, or an excessive amount of water is removed by a compression mechanism of the extruder by providing a drainage mechanism in the extruder. do it. When the amount of water is small, it is sufficient to add a predetermined amount of water or a polycarbonate resin powder with a large amount of water, and when adding, add from the vent hole etc. of the extruder supplying the polycarbonate resin powder. Is preferred. Further, 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.

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, the desired drying property is extremely excellent, and it becomes difficult to obtain a polycarbonate resin powder having a very small amount of residual organic solvent.

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. At the tip of the screw, a screw having a function of sending out the polycarbonate resin fine powder just before the die may be used. 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. The shape is not particularly limited, but is generally circular from the working surface of the hole. The structure of the die holes is extrusion capacity, drying efficiency,
From the viewpoint of handling, etc., a hole diameter of 0.1-5 mm is appropriate.
0.5 to 3 mm is preferable, and the land may have the same hole diameter to pass through the die, or may be a multi-stage communication hole having different hole diameters with the same hole axis. The ratio of the land length (L) to the hole diameter (D) is L / in terms of the strength of the obtained granular material, the discharge pressure, the strength of the die, and the like.
The range in which D is 1 to 10 is preferable. 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 polycarbonate resin powder particles to be supplied to a diameter of 50 μm or less, and has a kneading function and a deliquoring function. Is preferred. A method in which a kneading disk and / or a seal ring are combined to provide the function is preferably used. Examples of the extruder include a single-screw or multi-screw screw extruder, a plunger extruder, or 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 a screw. Further, a cylinder with a vent, a cylinder with a taper, a screw having a compression part, and the like can also be used. For the liquid removing function, a punching plate or a slit for liquid removing may be provided on all or part of the cylinder, or a liquid removing mechanism may be provided on the ground side. Most of the excess water contained in the polycarbonate resin granules, such as separated water and attached or contained water, is separated on the opposite side of the die or by a punch plate or slit. The openings of the gland and the punch plate, the clearance of the slit, etc. are not particularly limited, and may be appropriately selected depending on the particle size of the polycarbonate resin powder particles supplied, the amount of water of 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. If necessary, it may be dried after being subjected to any organic solvent removal treatment such as a method of mixing with a liquid having a boiling point of the residual organic solvent or higher and a method of contacting with steam, and extraction with a poor solvent or a non-solvent. Or addition treatment may be performed. When the amount of residual organic solvent of the obtained polycarbonate resin powder is large and the powder is likely to collapse, a device that does not apply a shear, for example, a hot air circulation dryer, a steam tube dryer, a pow heater,
It is preferable to dry using a hopper dryer or the like, or to dry in advance with these devices and then further dry using a drying device such as a paddle dryer or a multi-fin dryer. The polycarbonate resin powder thus obtained may contain optional stabilizers, additives, fillers and the like at any stage, if necessary.

[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.
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.

Example 1 (A) 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 put into a kneader charged with warm water kept at 42 ° C. After removing methylene chloride and coarse crushing,
The temperature is raised to 60 ° C. under stirring and kept for 1 hour to obtain a powder concentration of 25%,
A slurry with a methylene chloride content of 8% was obtained. (B) A single screw extruder with a diameter of 40 mm, an L / D of 9.25, no compression section, a groove depth of 6 mm, and a cylinder with a temperature control jacket was used. A die with 82 holes of 2 mm and a land length of 5 mm was provided, and a cutting machine (50 mm long 1
Single blade propeller) and jacket temperature of 15 ℃,
Screw rotation speed is 20 rpm, cutting machine rotation speed is 80 rpm
Set to. While continuously supplying the slurry obtained in (A) above to the hopper of an extruder, a methylene chloride solution of the polycarbonate resin used in (A) above was continuously injected through a vent hole provided in the center of the cylinder, and extruded. It was pulverized in a machine and extruded to obtain a granular body. The amount of slurry supplied is 4.
The injection amount of the methylene chloride solution of the polycarbonate resin was 5 kg / hour, the injection amount was 0.38 kg / hour, and the extrusion amount was 1.8 kg / hour. At this time, the total amount of resin is 1.24 kg / hour, and the total amount of methylene chloride is 25%. The obtained granules have a water content of 19
%, And the methylene chloride content was 21%. 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 6.7 ppm and a bulk density of 0.60 g / m 2.
l, about 95% of which passed through 8 mesh, to obtain granules remaining in all 14 mesh. 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 2 An aqueous slurry of the polycarbonate resin powder granules obtained in Example 1 (A) was heated to 95 ° C. with stirring and kept for 1 hour to maintain a methylene chloride content of 0.8% and powder. A water slurry having a particle concentration of 25% was obtained. When this slurry was continuously supplied to the extruder used in Example 1, 2.7 kg / hour of water was discharged from the ground side of the extruder. 1
A methylene chloride solution of the polycarbonate resin used in (A) was continuously injected, finely ground in an extruder, and extruded to obtain a granular body. The slurry supply rate was 3.6 kg / hour, the water injection rate was 0.5 kg / hour, and the methylene chloride solution injection rate was 0.
It was 5 kg / hour. The total amount of resin at this time is 0.975 kg
/ H, the amount of methylene chloride becomes 30.7%. The obtained granular material had a water content of 28% and a methylene chloride content of 25%. The obtained granules are dried at 145 ° C by a hot air circulation dryer.
After drying for 6 hours, a residual methylene chloride amount of 5.8 ppm, a bulk density of 0.59 g / ml, and about 95% of which passed through 8 mesh, and a granule that remained on all 14 mesh was 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.

[Embodiment 3] 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.
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), 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. Example 1 From the vent provided at the center of the cylinder while continuously supplying the water slurry of the polycarbonate resin powder obtained in Example 1 (A) to the hopper of the extruder.
A methylene chloride solution of the polycarbonate resin used in (A) was continuously injected, finely ground in an extruder, and extruded to obtain a granular body. The amount of slurry supplied is 73.8 kg / hour, and the amount of methylene chloride solution of polycarbonate resin injected is 15 kg.
/ Hour, the extrusion rate was 37.5 kg / hour. At this time, the total amount of resin was 20.7 kg / hour, and the total amount of methylene chloride was 41%. The obtained granular material had a water content of 25% and a methylene chloride content of 36%. The obtained granules were dried at 145 ° C. for 6 hours by a hot air circulation dryer, the residual methylene chloride amount was 3.8 ppm, the bulk density was 0.59 g / ml, and about 95% passed through 8 mesh, and all were 14 mesh. A granular material remaining in the above 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 30 μm.

[Example 4] An agglomerate obtained in the same manner as in Example 4 except that the die and the cutter were removed, was crushed by a hammer mill with a screen having an opening of 5 mm to give a water content of 27% and a methylene chloride content. 37% polycarbonate resin powder was obtained. 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, 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 to be an aggregate of fine powder having a diameter of 2 to 20 μm.

Example 5 The methylene chloride solution of the polycarbonate resin used in Example 1 (A) was dropped into warm water kept at 45 ° C. under stirring, treated with a wet pulverizer and then circulated in a stirring tank. Methylene chloride is removed and the concentration of particles is 2
A water slurry with 0% and methylene chloride content of 20% was obtained.
To this slurry, 10% of n-heptane was added with stirring to the powder and granules, mixed for 20 minutes, heated to 95 ° C. with stirring, and held for 1 hour to contain powder concentration 20% and methylene chloride. An amount of 0.5% water slurry was obtained. While continuously supplying this slurry to the twin-screw extruder used in Example 3, water and Example 1 were introduced through a vent hole provided in the center of the cylinder.
To the methylene chloride solution of the polycarbonate resin used in (A), a solution in which 10% of n-heptane was added and mixed was continuously poured into the solution, pulverized in an extruder, and extruded to obtain granules. . The slurry supply rate is 100 kg / hour,
The injection amount of water was 20 kg / hour, and the injection amount of the methylene chloride solution mixed with n-heptane was 6.8 kg / hour. At this time, the total amount of resin is 21 kg / hour, and the amount of methylene chloride is 20%. The obtained granular material had a water content of 22% and a methylene chloride content of 18%. The obtained granules were dried at 120 ° C. for 1 hour by a hot air circulation type dryer and then dried at 145 ° C. for 6 hours by a paddle dryer to give a residual methylene chloride amount of 0.5 ppm, n-heptane amount of 60 ppm and a bulk density of 0. 60
About 93% of g / ml passed through 6 mesh to obtain granules remaining in 8 mesh. The folded surface of this granular material was magnified 1000 times with an electron microscope, and the diameter was 2 to 2.
It was confirmed to be an aggregate of fine powder of 0 μm.

Example 6 (C) 10% n-heptane was added to and mixed with 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. The resulting solution was put into a kneader charged with warm water kept at 42 ° C to remove methylene chloride and coarsely pulverized, then heated to 60 ° C with stirring and kept for 1 hour to obtain a powder concentration of 2
A slurry with 5% and methylene chloride content of 2% was obtained. While continuously supplying the obtained slurry to the twin-screw extruder used in Example 3, 10-n-heptane was added to a methylene chloride solution of the polycarbonate resin used in the above (C) through a vent provided in the center of the cylinder. % Added mixed solution was continuously injected, finely pulverized in an extruder and extruded to obtain granules. The slurry supply rate was 60 kg / hour, and the injection rate of the methylene chloride solution mixed with n-heptane was 20 kg / hour. At this time, the total amount of resin was 17.7 kg / hour, and the total amount of methylene chloride was 46.8%. The obtained granules have a water content of 3
The content was 7% and the methylene chloride content was 44.5%. The granules were dried with a hot air dryer at 145 ° C. for 6 hours to give a residual methylene chloride content of 0.8 ppm and a residual n-heptane content of 70 ppm.
A bulk density of 0.57 g / ml, about 95% 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.

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 then stirred at 95 ° C.
The temperature was raised to 1 hour and held for 1 hour, followed by centrifugal dehydration and drying with a hot air dryer at 145 ° C. for 6 hours. The obtained powder and granules had 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. When the powder and granules were magnified 1000 times by an electron microscope, it was confirmed that the powder and granules had a particle diameter of almost 70 to 3000 μm and were not aggregates of fine powder.

Comparative Example 2 Extrusion was carried out in the same manner as in Example 2 except that the addition of water in Example 2 was stopped, and the water content was 2
%, And a methylene chloride content of 33% was obtained as a polycarbonate resin granule. This granular material is heated to 145 ° C by a hot air dryer.
After drying for 6 hours, a granular material having a residual methylene chloride content of 1800 ppm and a bulk density of 0.61 g / ml was obtained. When the granules were magnified 1000 times with an electron microscope, it was confirmed that most of them were continuous layers and the fine powder particles were in close contact with each other.

[0031]

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 obtained polycarbonate resin granules have a uniform particle size and are excellent in moldability and handleability, and the industrial effect produced by them is exceptional. It is a thing.

Front page continued (72) Inventor Yoshifumi Ikemura 1-6-21 Nishishinbashi, Minato-ku, Tokyo Teijin Kasei Co., Ltd. (72) Inventor Katsuhiro Kona 1-6-21 Nishishinbashi, Minato-ku, Tokyo Teijinka Within Cheng Co., Ltd.

Claims (2)

[Claims] 1. A solid polycarbonate resin slurry containing an organic solvent in an amount of 50 ppm to 10% by weight is continuously fed 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 pulverizing, and at the time of finely pulverizing, 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 finely pulverizing is based on the total weight of the organic solvent and the polycarbonate resin. A method for producing a polycarbonate resin powder, which comprises 10 to 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.