JPH07278288A - Preparation of polycarbonate resin powder - Google Patents

Abstract

PURPOSE:To efficiently prepare a polycarbonate resin powder, from an org. solvent soln. of a polycarbonate resin, which has an excellent drying property and has a very low residual org. solvent content attained by a conventional drying method. CONSTITUTION:A polycarbonate resin contg. an org. solvent in such an amount as will cause crystallization of the polycarbonate resin at room temp. under atomospheric pressure is heated or heated under pressure to prepare a liquid which is then continuously fed into an extruder, where the polycarbonate is granulated and, at the same time, pulverized to a diameter of not more than 50mum. The powder is extruded without melting or dissolution and cut or ground. Not less than 5wt.% water is allowed to exist during the pulverization, and the org. solvent content of the polycarbonate resin during the pulverization is brought to 10 to 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 for easily producing a polycarbonate resin powder granule having an extremely small amount of residual organic solvent, a low melting point, a uniform particle diameter, and excellent handleability and extrudability.

[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 of removing the organic solvent from the organic solvent solution of the polycarbonate resin to obtain a granular material, for example, a polycarbonate resin having an organic solvent content of 25% by weight or less is used, which is equipped with a heated vent having a twin screw. A method of supplying powder to a cylinder and evaporating an organic solvent to obtain a granular material (JP-A-51-41048 and JP-A-54-3897), and supplying an organic solvent solution of a polycarbonate resin into hot water. A method is known in which a gelled product is formed by crushing the gelled product. However, in the former method, since the heat transfer area is small, the production efficiency is poor, and the bulk density of the obtained powder or granule is low, and the handleability thereof is poor. Further, a resin film is formed on the inner wall of the cylinder, and due to this retention, serious problems such as coloring of the resin and reduction of the molecular weight are likely to occur. In the latter method, a complicated step of separating a solid and a liquid is required, and since a large amount of an organic solvent and water are contained in the obtained granular material, there is a drawback that a great amount of energy and time are required for subsequent drying. However, since water and organic solvents are removed at high temperature, there is a drawback that corrosion of the equipment due to generation of acidic gas increases and a large amount of foreign matter is mixed in the powder or granules.

A method of flaking or pulverizing a solution of a polycarbonate resin in an organic solvent by contacting it with hot water or steam (Japanese Patent Publication No. 36-11231 and Japanese Patent Publication No. 40-).
9843, JP-B-45-9875, JP-B-48-43752, JP-B-54-122393), a method of gelation by concentration and cooling (JP-B-36-21033). , Shokoku Sho 38-22
497, Japanese Patent Publication No. 40-12379, Japanese Patent Publication No. 45-9875, Japanese Patent Publication No. 47-41421, Japanese Patent Publication No. 51-41048) and the like are 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 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) has been proposed. However, there is a problem that some polycarbonate resin particles obtained by this method do not sufficiently remove the amount of residual organic solvent.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for efficiently producing a polycarbonate resin powder granule having excellent drying property from a solution of a polycarbonate resin in an organic solvent and having a very small residual organic solvent by ordinary drying. To provide.

As a result of earnest studies aimed at achieving the above object, the present inventor concentrated an organic solvent solution of a polycarbonate resin to obtain a polycarbonate resin containing an amount of an organic solvent which crystallizes at room temperature under normal pressure. Is heated or heated and pressurized to be liquefied and supplied to the extruder, granulated in the extruder and finely pulverized to a specific diameter or less in the presence of a specific amount of water, and extruded without melting or melting to cut or pulverize. If so, the drying property is extremely excellent, and it is possible to easily obtain a powder or granule having a very small amount of residual organic solvent by ordinary drying.
It was found that the obtained powder and granules have a low melting temperature and excellent moldability. 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, the melting point is low, and the particle size is uniform. The present invention has been completed by the finding that a granular material having the following characteristics can be obtained.

[0007]

According to the present invention, a polycarbonate resin containing an organic solvent in an amount capable of crystallizing under normal temperature and pressure is heated or heated and pressurized to be liquefied and continuously supplied to an extruder. Diameter 50 while granulating in the machine
It consists of finely pulverizing to less than μm, 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 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, and a part or all thereof is crystallized from a solution of the organic solvent to obtain a solid. It is a possible polycarbonate resin. 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. Other dihydric phenols include, for example, bis (4-hydroxyphenyl) methane, 1,1-bis (4-hydroxylphenyl) ethane, 1,1-bis (4-hydroxylphenyl) cyclohexane, 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 Examples thereof include halogenated bisphenols such as (3,5-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, etc. may be used, and the polycarbonate resin may be, for example, a branched polycarbonate resin obtained by copolymerizing a polyfunctional aromatic compound having three or more functional groups, or two types. It may be a mixture of the above polycarbonate resins. Any molecular weight of the polycarbonate resin can be used. 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. The specific viscosity (η _SP ) measured at 20 ° C. is preferably 3.00 or less, particularly preferably 0.19 to 1.50.

The polycarbonate resin containing an organic solvent used in the present invention may be obtained by any method, but in particular, a polycarbonate resin obtained by reacting an alkaline aqueous solution of a dihydric phenol with phosgene in the presence of an organic solvent. Those obtained by washing the solution with water and concentrating it are preferable. The organic solvent used here is a good solvent for the polycarbonate resin, preferably methylene chloride, and may be one kind or a mixture of two or more kinds. Further, a non-solvent or a poor solvent may be mixed in such an amount that it does not crystallize under heat or pressure. Any stabilizer, additive, filler, etc. may be added to the polycarbonate resin containing an organic solvent, if necessary.

If the content of the organic solvent is too large, the amount of the solvent to be recovered will be large and the efficiency will be poor, and it will be difficult to granulate in the extruder. If it is too small, liquefaction of the polycarbonate resin will require high temperature and high pressure. The supply to the extruder becomes difficult, and the load at the time of fine pulverization in the extruder is large, which makes fine pulverization difficult. Therefore, the amount should be such that the polycarbonate resin crystallizes at room temperature and normal pressure. The specific amount of the organic solvent varies depending on the type of the organic solvent and the solubility of the polycarbonate resin and cannot be specified unconditionally. For example, when the organic solvent is methylene chloride and the polycarbonate resin is obtained from bisphenol A, it is usually 1
It is 0 to 75% by weight, preferably 15 to 65% by weight. When the amount of organic solvent is not appropriate, it may be adjusted by an appropriate means. When the amount of the organic solvent is small, for example, a predetermined amount of the organic solvent or the organic solvent solution of the polycarbonate resin may be added, and when the amount of the organic solvent is large, for example, heating is performed to remove the excess organic solvent or the organic solvent. It suffices to add powdery particles of a polycarbonate resin having a low content.
In addition, the normal temperature here is a temperature of about 10 to 35 ° C., and the normal pressure is a state in which neither pressurization nor depressurization is carried out. is there. The water content is not limited in any way.

In the present invention, the polycarbonate resin containing the above-mentioned amount of the organic solvent is heated or heated and pressurized to be liquefied and supplied to the extruder. If the heating temperature and the pressurizing pressure are too high, the liquefaction temperature is 15 because the quality of the obtained product, equipment, safety, cost, etc. are not preferable.
The temperature is preferably 0 ° C. or lower, and when the pressure is applied, the pressure is preferably 16 kg / cm ² or less.

The polycarbonate resin liquefied by heating or heating and pressing is continuously supplied to the extruder, finely pulverized while granulating in the extruder, and extruded without melting or melting. A polycarbonate resin containing a predetermined amount of an organic solvent which has been heated or heated and pressurized to be liquid is cooled in an extruder and crystallized to be powdery or lumpy (hereinafter abbreviated as powdery or granular material). When the amount of organic solvent is large in this granulation stage,
The extruder may be suitably heated to evaporate off excess organic solvent and should be such that the polycarbonate resin does not melt or dissolve when heated. 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. The amount of organic solvent in the granular material is covered by the organic solvent contained in the polycarbonate resin supplied to the extruder, but when this amount of organic solvent is not suitable, it is adjusted by adding or removing the organic solvent. do it. For example, when the amount of the organic solvent is small, an organic solvent, an organic solvent solution of a polycarbonate resin, 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. Upon addition, it may be added directly to the polycarbonate resin supplied to the extruder, or may be added through a vent hole or the like of the extruder. When the amount of the organic solvent is large, a polycarbonate resin powder having a low content of the organic solvent may be added to the polycarbonate resin supplied to the extruder, or the excess organic solvent may be removed by heating in advance. In addition, the polycarbonate resin powder in the extruder,
Excess organic solvent may be removed by heating so as not to melt or dissolve. For example, the temperature of the extruder used may be adjusted so as not to melt or dissolve the polycarbonate resin particles, and excess organic solvent may be removed from the vent hole. In addition, in adjusting, it is preferable to mix uniformly.

Also, 5% by weight in the fine grinding stage in the extruder
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 during the 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 fine pulverization 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 melting or melting and is extruded as an agglomerate of fine powder. If it is melted or melted 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 the working surface of the hole The round shape is common. The hole structure of the die is preferably 0.1 to 5 mm from the viewpoints of extrusion ability, drying efficiency, handleability, etc.
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 / D of 1 from the viewpoint of the strength of the obtained granular material, the discharge pressure, and the strength of the die.
It is preferably 10 to 10. When using a die having multi-stage communication holes, 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 powdery polycarbonate resin particles crystallized in the extruder to a diameter of 50 μm or less. , Those having a kneading function are preferable, and those having a liquid removing function may be used. 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 rises in the cylinder internal temperature and internal pressure.A jacket with a temperature control mechanism to avoid such troubles. It is preferable to use an attached cylinder or screw. Further, a cylinder with a vent, a cylinder with a taper, and a screw with a compression section are also used. As a liquid removing function, a punch plate or a slit for liquid removing may be provided on all or part of the cylinder, or a drainage mechanism may be provided on the gland side. Most of the excess water contained in the polycarbonate resin powder during extrusion, such as separated water, water that is attached or contained, is separated on the opposite side of the die, or separated by a punch plate or slit. To be done. 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 diameter of the polycarbonate resin powder particles produced in the granulation step, the water content thereof, 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 performing any organic solvent removal treatment such as a method of mixing with a liquid or the like having a boiling point of the residual organic solvent or higher and a method of contacting with steam. In addition, extraction or addition treatment may be performed with a poor solvent or a non-solvent. 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. Stabilizers, additives, fillers and the like may be added to the polycarbonate resin powder thus obtained, if necessary.

[0023]

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) Specific viscosity (η _SP ): Polycarbonate resin 0.7g
Was dissolved in 100 ml of methylene chloride at 20 ° C.
Measured with an Ostworld viscometer. (2) Melting point: differential scanning calorimeter [910 DS manufactured by DuPont]
C]. (3) Methylene chloride content: The chlorine content was analyzed by a total organic halogen analyzer [TOX manufactured by Mitsubishi Kasei Co., Ltd.] and converted into the amount of methylene chloride. (4) Amount of n-heptane: Gas chromatography [Co., Ltd.]
Hitachi 263 model] was used as a column packing material using dioctyl sebacate, and the measurement was performed by a headspace method at 250 ° C. (5) 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 of "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.

[Embodiment 1] A gas outlet, a nitrogen gas inlet, a gas outlet provided with a pressure adjusting valve at the outlet and a gas condenser are provided at the upper portion, a liquid temperature detector is provided at the side surface, and an outlet is provided at the lower portion. 300 parts of a 15% methylene chloride solution of a polycarbonate resin having a specific viscosity of 0.445 obtained from bisphenol A and phosgene by a conventional method in a stirring concentration tank with a jacket equipped with
Supply under stirring, blow nitrogen gas from the nitrogen gas inlet,
Methylene chloride was evaporated at an internal pressure of 3 kg / cm ² and a liquid temperature of 45 ° C., and when the evaporation amount of methylene chloride reached 235.7 parts (methylene chloride content 30%), degassing was stopped,
The solution was kept under pressure at 45 ° C. under nitrogen pressure. A twin-screw extruder [TEM-50B manufactured by Toshiba Machine Co., Ltd.] having a screw diameter of 57 mm and an L / D of 28.4, in which a cylinder is provided with a temperature control jacket composed of 8 blocks excluding the supply port, A die with 173 holes with a hole diameter of 2 mm and a land length of 6 mm was installed at the exit, and a cutting machine (50 mm in length) was placed in front of the die at intervals of 4 mm.
Single blade propeller), jacket temperature (all 8 blocks) 15 ° C, screw speed 80 rpm,
The cutting machine speed was set to 200 rpm. The polycarbonate resin with a methylene chloride content of 30% held in the liquid state is continuously supplied to the extruder through the outlet at the bottom of the concentration tank, and at the same time, at the center of the cylinder (excluding the supply section, the third block from the supply side). Water was continuously injected from the vent provided in (1). Methylene chloride content held in liquid form 30
% Of polycarbonate resin is 86.7 kg / hour,
The water supply rate was 12.1 kg / hour, and the extrusion rate was 90 kg / hour. At this time, the amount of resin is 60.7 kg / hour and the amount of water is 20.
%become. The granules were granulated in the extruder, pulverized and extruded to obtain granules having a water content of 15% and a methylene chloride content of 25%. The granules were dried by a hot air circulation dryer at 145 ° C for 6 hours to give a residual methylene chloride content of 6.5 ppm, a bulk density of 0.60 g / ml, a melting point of 240 ° C and about 95% of which passed through 8 mesh. A granular material remaining on 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.

[Example 2] Granules were extruded in the extruder, finely pulverized and extruded in the same manner as in Example 1 except that the die and the cutter were removed.
The obtained agglomerates were crushed by a hammer mill with a screen having an opening of 5 mm to obtain a polycarbonate resin powder having a water content of 18% and a methylene chloride content of 27%. The powder and granules were dried at 145 ° C. for 6 hours by a hot air circulation dryer to obtain a residual methylene chloride content of 3.4 ppm and a bulk density of 0.62 g / m 2.
l, melting point 240 ° C., average particle size 0.79 mm, n is 1.41
To obtain a granular material. 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] The liquid temperature in the concentrating tank is set to 65.
℃, change the amount of methylene chloride evaporated liquid to 210 parts (methylene chloride content 50%), set the two blocks to 50 ° C from the supply side except the supply part of the extruder, and keep them in liquid form. Polycarbonate resin with 50% methylene chloride content is continuously fed to the extruder through the outlet at the bottom of the concentration tank,
Water was continuously injected from the vent of the third block while removing methylene chloride gas from the vent of the second block.
The supply amount of the polycarbonate resin having a methylene chloride content of 50% held in a liquid state was 102.1 kg / hour, the supply amount of water was 15.3 kg / hour, and the extrusion rate was 90 kg / hour. At this time, the amount of resin is 51.1 kg / hour, and the amount of water is 30%. The mixture was granulated in the extruder, pulverized, and extruded to obtain granules having a water content of 27% and a methylene chloride content of 33%.
The granules were dried at 145 ° C. for 6 hours with a hot air circulation dryer to obtain a residual methylene chloride content of 5.2 ppm and a bulk density of 0.5.
9 g / ml, melting point 235 [deg.] C., about 95% passed through 8 mesh to obtain granules remaining in all 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 Polycarbonate Resin 15
% Methylene chloride remaining amount 0.5 ppm, residual n-heptane amount 40 ppm, bulk density 0.60 g / ml, melting point in the same manner as in Example 1 except that 5 parts of n-heptane was added to and mixed with 300 parts of 100% methylene chloride solution. At 220 ° C., about 95% of the powder passed through 8 mesh, and a granular material remained in 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.

Comparative Example 1 The specific viscosity used in Example 1 was 0.
200 parts of a 15% methylene chloride solution of 445 polycarbonate resin in a kneader charged with 10 parts of warm water at 40 to 42 ° C. and a vapor pressure of 3 kg at a speed for maintaining a dough-like state under stirring.
It was charged together with water vapor of / cm ² in 90 minutes. After stopping the addition of water vapor to gel, coarsely pulverize, further pulverize with a hammer mill with a screen of 4 mm opening, raise the temperature to 95 ° C under stirring and hold for 1 hour, centrifuge and dehydrate, and circulate hot air. It dried at 145 degreeC by the dryer for 6 hours. The obtained granules have a residual methylene chloride content of 78 ppm and a bulk density of 0.62.
g / ml, melting point 250 ° C., average particle size 0.51 mm, n = 1.
It was 02. This powder and granules are examined with an electron microscope to 1000
Upon doubling, it was confirmed that the particles were almost 70-3000 μm in particle size and not an agglomerate of fine powder.

Comparative Example 2 The polycarbonate resin granules obtained in the same manner as in Example 1 except that water was not injected from the vent had a residual methylene chloride content of 93 ppm and a bulk density of 0.63 g / ml. . When this granular material was magnified 1000 times with an electron microscope, it was confirmed to be a continuous layer over the entire surface.

[0030]

According to the present invention, the drying property is extremely excellent,
Polycarbonate resin granules with extremely 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 effect they produce is exceptional. Is.

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 polycarbonate resin containing an organic solvent in an amount capable of crystallizing at normal temperature and pressure is liquefied by heating or heating and pressurizing, and continuously supplied to an extruder. It consists of finely pulverizing to 50 μm or less, and extruding without melting or dissolving and cutting 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 A method for producing a polycarbonate resin powder, wherein the amount of the solvent is 10 to 65% by weight based on the total weight of the organic solvent and the polycarbonate resin. 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.