JPH04331237A - Production of polycarbonate powder - Google Patents

Abstract

PURPOSE:To produce easily a polycarbonate powder having a high bulk density and a low residual solvent content while preventing the obtained polycarbonate powder from changing its properties even when the amount of the organic solvent solution of the polycarbonate treated is changed. CONSTITUTION:An organic solvent solution of a polycarbonate with a concentration of 3-45wt.% and steam in an amount which is 1/20 to 1/8 time as large as the weight of the organic solvent are fed to a mixing nozzle 1. The mixture injected from this nozzle is mixed with steam in an amount which is 1/200 to 1/1 time as large as the weight of the organic solvent after a residence time of 0.001-1sec to obtain the second mixture, and a polycarbonate powder is recovered from this second mixture.

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 powder.

0002

[Prior Art] There are two methods for producing polycarbonate: the melt polycondensation method (ester exchange method) and the interfacial polycondensation method (phosgene method). The interfacial polycondensation method is preferably used as a method for industrially producing polycarbonate. has been done. In a method for producing polycarbonate based on an interfacial polycondensation method, an emulsion solution obtained by an interfacial polycondensation reaction is washed and separated to first obtain a solution of polycarbonate in an organic solvent (the solvent is generally methylene chloride). Next, polycarbonate is separated (recovered) as powder or granules from the obtained organic solvent solution. Thereafter, if necessary, the obtained polycarbonate is molded into a pellet shape or the like.

[0003] A simple method for recovering polycarbonate as a powder from an organic solvent solution of polycarbonate is to introduce a polycarbonate organic solvent solution and steam into one jet nozzle (mixing nozzle), and to collect the mixture sprayed from the mixing nozzle. Introduced into the separator through piping,
A method of separating polycarbonate powder using this separator is known (Japanese Patent Publication No. 63-1333, Japanese Patent Publication No. 2-6561, and US Pat. No. 3,508,339). This method includes a method of adding a poor solvent to an organic solvent solution of polycarbonate (Japanese Patent Publication No. 14474/1982), and a crushing method using a kneader that utilizes crystallization of a solution of polycarbonate in an organic solvent (Japanese Patent Publication No. 15899/1989).
This method has the advantage that polycarbonate powder with a small amount of residual solvent can be easily recovered compared to methods such as the method of pouring an organic solvent solution of polycarbonate into hot water (Japanese Patent Application No. 60-115625), etc. are doing.

0004

[Problems to be Solved by the Invention] However, the bulk density of polycarbonate obtained by the conventional method of introducing an organic solvent solution of polycarbonate and steam into a mixing nozzle and recovering polycarbonate as a powder from the mixture sprayed from this mixing nozzle is low. is as low as 0.05 to 0.35. For this reason, the volumetric efficiency of processing equipment when performing post-processing such as drying, storage, granulation, and molding on the obtained polycarbonate powder is also low, and it is necessary to use large-sized processing equipment for these processing equipment or to use it. The problem was that production adjustments had to be made to match the volume of the processing equipment. Furthermore, in the conventional method described above, if the amount of polycarbonate organic solvent solution to be processed changes, the properties of the obtained polycarbonate powder (bulk density, amount of residual solvent, etc.) change significantly, making it impossible to process it in the post-processing step. Another problem was that mechanical problems such as these frequently occurred.

Therefore, an object of the present invention is to easily obtain a polycarbonate powder with a high bulk density and a small amount of residual solvent, and to maintain the properties of the polycarbonate powder obtained even when the amount of the organic solvent solution of polycarbonate is varied. It is an object of the present invention to provide a method for producing polycarbonate powder with small changes.

[0006]

[Means for Solving the Problems] The method for producing polycarbonate powder of the present invention that achieves the above object includes an organic solvent solution in which the concentration of polycarbonate is 3 to 45% by weight, and the weight of the organic solvent in this organic solvent solution. 1/20~1/8 of
1/2 of the weight of the organic solvent in the organic solvent solution after a residence time of 0.001 to 1 second.
The method is characterized in that a second mixture is obtained by mixing with 00 to 1/1 times the weight of steam, and polycarbonate is recovered as a powder from this second mixture.

The present invention will be explained in detail below. First, the organic solvent solution of polycarbonate (hereinafter sometimes simply referred to as organic solvent solution) used in the present invention will be explained. As mentioned above, the concentration of polycarbonate in this organic solvent solution is 3 to 45% by weight (hereinafter, % by weight is abbreviated as wt%). Here, the reason why the lower limit of the concentration of polycarbonate is limited to 3 wt% is that if it is less than 3 wt%, the productivity of polycarbonate powder becomes too low. In addition, the upper limit of the concentration of polycarbonate was set to 4.
The reason why it is limited to 5 wt% is that if it exceeds 45 wt%, the fluidity of the organic solvent solution decreases too much, making it difficult to introduce it into the mixing nozzle (hereinafter sometimes referred to as the first mixing nozzle). A particularly preferred polycarbonate concentration is 10 to 30 wt%. The type of polycarbonate mentioned above is not particularly limited, and various polycarbonates obtained by reacting dihydric phenol with phosgene or a carbonate compound can be used. Examples of divalent phenols and carbonate ester compounds are as follows.

■Dihydric phenol 2,2'-bis(4-hydroxyphenyl)propane (
Bisphenol A), bis(4-hydroxyphenyl)
Methane, bis(4-hydroxyphenyl)phenylmethane, bis(4-hydroxyphenyl)naphthylmethane,
Bis(4-hydroxyphenyl)-(4-isopropylphenyl)methane, diphenyl-bis(4-hydroxyphenyl)methane, bis(3,5-dichloro-4-hydroxyphenyl)methane, bis(3,5-dimethyl- 4
-hydroxyphenyl)methane, 1,1-bis(4-hydroxyphenyl)ethane, 1-naphthyl-1,1-bis(4-hydroxyphenyl)ethane, 1-phenyl-
1,1-bis(4-hydroxyphenyl)ethane, 1,
2-bis(4-hydroxyphenyl)ethane, 2-methyl-1,1-bis(4-hydroxyphenyl)propane, 2,2-bis(3,5-dimethyl-4-hydroxyphenyl)propane, 1-ethyl -1,1-bis(4-hydroxyphenyl)propane, 2,2-bis(3,5-
dichloro-4-hydroxyphenyl)propane, 2,2
-bis(3,5-dibromo-4-hydroxyphenyl)
Propane, 2,2-bis(3,5-dichloro-4-hydroxyphenyl)propane, 2,2-bis(3-methyl-4-hydroxyphenyl)propane, 2,2-bis(
3-fluoro-4-hydroxyphenyl)propane, 1
, 1-bis(4-hydroxyphenyl)butane, 3,2
-bis(4-hydroxyphenyl)butane, 1,4-bis(4-hydroxyphenyl)butane, 2,2-bis(
4-hydroxyphenyl)pentane, 4-methyl-2,
2-bis(4-hydroxyphenyl)pentane, 1,1
-bis(4-hydroxyphenyl)cyclohexane, 1
, 1-bis(3,5-dichloro-4-hydroxyphenyl)cyclohexane, 2,2-bis(4-hydroxyphenyl)hexane, 4,4-bis(4-hydroxyphenyl)heptane, 2,2-bis( Dihydroxyarylalkanes such as 4-hydroxyphenyl)nonane, 1,10-bis(4-hydroxyphenyl)decane and 1,1-bis(4-hydroxyphenyl)cyclododecane; bis(4-hydroxyphenyl)sulfone, bis (3
, 5-dimethyl-4-hydroxyphenyl) sulfone and bis(3-chloro-4-hydroxyphenyl) sulfone; bis(4-
dihydroxyaryl ethers such as hydroxyphenyl)ether and bis(3,5-dimethyl-4-hydroxyphenyl)ether; 4,4'-dihydroxybenzophenone and 3,3',5,5'-tetramethyl-4,4 -Dihydroxyarylketones such as dihydroxybenzophenone; bis(4-hydroxyphenyl)
Dihydroxyaryl sulfides such as sulfide, bis(3-methyl-4-hydroxyphenyl) sulfide and bis(3,5-dimethyl-4-hydroxyphenyl) sulfide; dihydroxyaryl sulfoxides such as bis(4-hydroxyphenyl) sulfoxide ;4
, 4'-dihydroxydiphenyl; dihydroxybenzenes such as hydroquinone, resorcinol and methylhydroquinone; dihydroxynaphthalenes such as 1,5-dihydroxynaphthalene, 2,6-dihydroxynaphthalene; etc.

■ Diaryl carbonate such as carbonate ester compound diphenyl carbonate,
Dialkyl carbonates such as dimethyl carbonate and diethyl carbonate.

The type of organic solvent is also not particularly limited as long as it dissolves polycarbonate and can be removed by evaporation with steam. As such an organic solvent, methylene chloride is preferred, but ethylene chloride, chloroform, carbon tetrachloride, dioxane, tetrahydrofuran, etc. can also be used. These organic solvents may be used alone or as a mixture. In the present invention, the above-mentioned organic solvent solution and steam having a weight of 1/20 to 1/8 times the weight of the organic solvent in this organic solvent solution (hereinafter sometimes referred to as WO1) are heated in the first step. Introduce into the mixing nozzle. Here, the lower limit of the weight of the steam introduced into the first mixing nozzle (hereinafter sometimes referred to as WS1) is set to 1/2 of WO1.
The reason for limiting it to 0 times is that if WS1 is less than 1/20 times WO1, the evaporation removal of the organic solvent will be insufficient.
This is because polycarbonate cannot be precipitated from an organic solvent solution. Further, the reason why the upper limit of WS1 is limited to 1/8 times WO1 is that if WS1 is more than 1/8 times WO1, the bulk density of the polycarbonate powder finally obtained will be too low.

[0011] The pressure of the steam introduced into the first mixing nozzle (the pressure when the nozzle is introduced) is 1 to 100 kg/cm2.
It is preferable that it is, especially 3 to 80 kg/cm2
It is preferable that Steam pressure is 1kg/cm
If it is less than 2, the mixing speed necessary for mixing the organic solvent solution and steam cannot be obtained. Also, in order to obtain steam exceeding 100 kg/cm2, high pressure equipment is required.
Equipment costs become unnecessarily high. Note that as the first mixing nozzle, any type of mixing nozzle commonly used can be used, but one having an ejector structure is preferable.

In the present invention, the mixture injected from the first mixing nozzle (hereinafter sometimes referred to as the first mixture) is mixed with the organic solvent in the organic solvent solution described above after a residence time of 0.001 to 1 second. 1/200 of the weight of the solvent (WO1)
Mix with ~1/1 times the weight of steam to obtain a second mixture. Here, the reason why the lower limit of the residence time (hereinafter sometimes referred to as τ) of the first mixture is limited to 0.001 seconds is that when τ is less than 0.001 seconds, the effect of using steam twice This is because it cannot be obtained. Also, set the upper limit of τ to 1
The reason why it is limited to seconds is that if τ exceeds 1 second, the polycarbonate will exist as a completely evaporated solid when mixed with steam, and the effect of mixing with steam will not be obtained. Also, the reason why the lower limit of the weight of the steam used to obtain the second mixture (hereinafter sometimes referred to as WS2) is limited to 1/200 times the weight of WO1 is that WS2
This is because if the amount is less than 1/200 times that of WO1, the amount of organic solvent remaining in the obtained polycarbonate powder will be too large. On the other hand, the reason why the upper limit of WS2 is limited to 1/1 times that of WO1 is that even if WS2 is increased to more than 1/1 times that of WO1, there is no change in the bulk density or residual solvent amount of the polycarbonate powder obtained. This is because the amount of steam will be .

[0013] The second mixture is produced by, for example, introducing the first mixture injected from the first mixing nozzle into the second mixing nozzle through piping so that the above-mentioned residence time is achieved, and at the same time, the second mixture is This can be obtained by introducing the above-mentioned predetermined amount of steam into the mixing nozzle. As the second mixing nozzle in this case, any type of mixing nozzle commonly used can be used, but one having an ejector structure is preferable. In addition, the first mixing nozzle and a separator etc. to be described later are connected by a pipe, and the residence time of the mixture (first mixture) injected from a predetermined position of this pipe, that is, the first mixing nozzle, is 0.001. ~1
The second mixture can also be obtained by, for example, providing a pipe for supplying steam at a position where the first mixture is mixed with the above-mentioned predetermined amount of steam.

In the present invention, polycarbonate is recovered as a powder from the second mixture obtained as described above. This recovery can be performed, for example, by introducing the second mixture into a separator such as a gas-solid separation cyclone through piping, and recovering the polycarbonate using the separator. In this case, the piping for introducing the second mixture into the separator may be a straight pipe or a curved pipe, but the length must be long enough to ensure residence time for the polycarbonate to evaporate to dryness, and The length should be such that the piping pressure loss is commensurate with the steam pressure. Note that steam and organic solvent vapor can be condensed and recovered in a condenser after separation of the polycarbonate powder. The polycarbonate powder thus obtained has a high bulk density and a small amount of residual solvent. Further, when polycarbonate powder is produced according to the present invention, even if the amount of the polycarbonate solution in an organic solvent is changed, the properties of the obtained polycarbonate powder change little. Therefore, even if the obtained polycarbonate powder is subjected to post-processing such as forming it into pellets through a drying and granulation process,
The volumetric efficiency of the equipment used for post-processing is high, and the occurrence of mechanical problems such as inability to perform processing in the post-processing step due to changes in the properties of the polycarbonate powder is also suppressed.

The present invention can also be applied as part of the process for producing polycarbonate by interfacial polycondensation method. In this case, an organic solvent solution of polycarbonate obtained by washing and separating an emulsion solution obtained by an interfacial polycondensation reaction is used as the polycarbonate solution in an organic solvent.

[0016]

[Examples] Examples of the present invention will be described below. Example 1 As shown in FIG. 1, a first mixing nozzle 1 into which a polycarbonate methylene chloride solution (hereinafter referred to as PCMC) and steam are introduced, and a mixture injected from this first mixing nozzle 1 are connected to a pipe. 10 and a second mixing nozzle 11 into which steam is also introduced; and a cyclone 21 into which the mixture (second mixture) injected from the second mixing nozzle 11 is introduced through piping 20. Polycarbonate powder was produced in the following manner based on the present invention.

First, Taflon A2200 manufactured by Idemitsu Petrochemical Co., Ltd. was used as a polycarbonate (hereinafter referred to as PC).
(trade name), dissolve this PC in methylene chloride (manufactured by Hiroshima Wako Pure Chemical Industries, Ltd., special grade), which is an organic solvent,
A methylene chloride solution of PC (hereinafter referred to as PCMC) having a concentration of 15 wt% was prepared. Then this PCMC
and steam at a pressure of 15 kg/cm2 and a temperature of 200°C at 140 kg/hr and 10 kg/hr, respectively.
were simultaneously introduced into the first mixing nozzle 1 using a diaphragm pump. The weight of the steam at this time (W
S1) is 1/11. of the weight of methylene chloride (WMC).
It is 9 times more.

Note that the first mixing nozzle 1 is as shown in FIG.
A mixing nozzle with the structure shown in was used. That is, this first
The mixing nozzle 1 includes a first nozzle 3 having a spout 2;
The second nozzle 4 is disposed such that the outer wall of the ejection beak is in contact with the inner wall of the ejection beak of the first nozzle 3. A mixing chamber 5 is formed in the inner space of the jetting beak of the first nozzle 3 . Further, the ejection beak of the first nozzle 3 is provided with a through hole 6 that communicates with the mixing chamber 5, and this through hole 6 communicates with the PCMC supply pipe 7. Note that the outer diameter a1 of the jetting beak of the first nozzle 3 is 50 mm, and the mixing chamber 5
The maximum diameter b1 is 30 mm, and the distance c1 from the tip of the second nozzle 4 to the end face on the jet nozzle 2 side in the mixing chamber 5 is 5.
0 mm, diameter d1 of the narrowest part in the internal space of the second nozzle
is 5 mm, and the diameter e1 of the jet nozzle 2 is 10 mm. In this mixing nozzle 1, PCMC introduced into the mixing chamber 5 via the PCMC supply pipe 7 and the through hole 6 is mixed with steam introduced into the mixing chamber 5 via the second nozzle 4 to form a mixture. It is injected from the spout 2.

The mixture injected from the first mixing nozzle 1 was introduced into the second mixing nozzle 11 through the pipe 10. As the piping 10 at this time, a stainless steel piping with an inner diameter of 10 mm was used, and the length of the piping 10 was such that the residence time τ of the mixture was 0.01 seconds. Also, this second
The mixing nozzle 11 has a pressure of 15 kg/cm2.
Steam at a temperature of 200° C. was simultaneously introduced at a rate of 3 kg/hr. Weight of steam at this time (WS2)
is 1/39.7 times the weight (WMC) of methylene chloride introduced into the first mixing nozzle 1.

As the second mixing nozzle 11, a mixing nozzle having the structure shown in FIG. 3 was used. That is, this mixing nozzle 11 includes a first nozzle 13 having a spout 12 and a second nozzle 14 disposed with the outer wall of the spout beak in contact with the inner wall of the spout beak of the first nozzle 13. ing. A mixing chamber 15 is formed in the internal space of the jetting beak of the first nozzle 13 . Further, the ejection beak of the first nozzle 13 is provided with a through hole 16 that communicates with the mixing chamber 15 , and this through hole 6 communicates with a steam supply pipe 17 . In addition, the outer diameter a2 of the ejection beak of the first nozzle 13
is 50 mm, the maximum diameter b2 of the mixing chamber 15 is 30 mm, and the jet nozzle 12 in the mixing chamber 15 from the tip of the second nozzle 14
The distance c2 to the side end face is 50 mm, the diameter d2 of the narrowest part in the internal space of the second nozzle is 10 mm, and the spout 1
The diameter e2 of 2 is 10 mm. In this mixing nozzle 11, the mixture from the first mixing nozzle 1 introduced into the second nozzle 14 through the piping 10 is introduced into the mixing chamber 15 via the second nozzle 14, and in this mixing chamber 15,
Mixing chamber 1 via steam supply pipe 17 and through hole 16
The steam is mixed with the steam introduced in 5 and is injected from the spout 12.

The mixture (second mixture) injected from the second mixing nozzle 11 passes through the pipe 20 to the cyclone 2.
The polycarbonate powder (hereinafter referred to as PC powder) is separated (recovered) by the cyclone 21, and the methylene chloride and steam are introduced into the condenser 2.
2 and collected. As the piping 20, a stainless steel piping with an inner diameter of 10 mm and a length of about 20 m was used. The apparatus shown in FIG. 1 was operated continuously for 2 hours. During the operation period, there were no problems such as blockages, and stable operation was possible. After 2 hours of operation, the desired PC powder was obtained from the lower part of the cyclone 21. The bulk density of the obtained PC powder and the residual amount of methylene chloride (hereinafter referred to as residual MC amount) are shown in Table 1.
Shown below.

Examples 2 to 12 The amount of PCMC and steam introduced into the first mixing nozzle 1 and the amount of steam introduced into the second mixing nozzle 11 were changed as shown in Table 1, and Mixing nozzle 1
Example 1 was carried out in the same manner as in Example 1, except that the length of the pipe 10 connecting the and second mixing nozzle 11 was appropriately set so that the residence time τ of the mixture was as shown in Table 1. PC powder was obtained using the device. Table 1 shows the bulk density and residual MC amount of each obtained PC powder. In addition, in any of the examples, during the operation period of the apparatus, there were no troubles such as blockage, and stable operation was possible.

Example 13 PC powder was obtained using the apparatus shown in FIG. 1 in the same manner as in Example 1 except that PCMC with a PC concentration of 12 wt % was used. Note that as the concentration of PC decreased from 15 wt% (Example 1) to 12 wt%, the first mixing nozzle 1
Steam introduction amount WS1 (=10kg/hr)
is 1/12.3 times the introduction amount WMC of methylene chloride, and WS2 (=3 kg/h
r) became 1/41 times that of WMC. Table 1 shows the bulk density and residual MC amount of the obtained PC powder. During the operation period of the device, there were no problems such as blockage, and stable operation was possible.

Example 14 PC powder was obtained using the apparatus shown in FIG. 1 in the same manner as in Example 1 except that PCMC with a PC concentration of 27 wt % was used. In addition, as the concentration of PC increased from 15 wt% (Example 1) to 27 wt%, the first mixing nozzle 1
WS1 (=10kg/hr) is 1/1 of WMC
0.2 times, and WS2 in the second mixing nozzle 11
(=3kg/hr) was 1/34 times that of WMC. Table 1 shows the bulk density and residual MC amount of the obtained PC powder. In addition, there were no problems such as blockages during the operation of the device.
It was stable and operable.

Examples 15 to 16 Amounts of PCMC and steam introduced into the first mixing nozzle 1,
and the amount of steam introduced into the second mixing nozzle 11,
PC powder was obtained using the apparatus shown in FIG. 1 in the same manner as in Example 1 except for the changes shown in Table 1. However, by changing the inner diameter of the pipe 10 connecting the first mixing nozzle 1 and the second mixing nozzle 11 to 20 mm in Example 15 and to 35 mm in Example 16, the residence time τ of the mixture was The time was set to 0.01 seconds, the same as in Example 1. Table 1 shows the bulk density and residual MC amount of each obtained PC powder. In addition, in any of the examples, during the operation period of the apparatus, there were no troubles such as blockage, and stable operation was possible.

Comparative Example 1 As shown in Table 2, PC powder was obtained using the apparatus shown in FIG. 1 in the same manner as in Example 1 except that no steam was supplied to the second mixing nozzle 11. At this time, from the outlet on the cyclone 21 side of the pipe 20 connecting the second mixing nozzle 11 and the cyclone 21, the solvent methylene chloride (liquid) was discharged together with the PC powder, which was found to be extremely unsuitable for practical use. Ta. Table 2 shows the bulk density and residual MC amount of the obtained PC powder.

Comparative Examples 2 to 5 As shown in Table 2, the amount of steam introduced into the first mixing nozzle 1 or the amount of steam introduced into the second mixing nozzle 11 was outside the limited range of the present invention. In the same manner as in Example 1, attempts were made to produce PC powder using the apparatus shown in FIG. However, by appropriately changing the length of the pipe 10 connecting the first mixing nozzle 1 and the second mixing nozzle 11 for each comparative example, the residence time τ of the mixture was 0.01 seconds, the same as in Example 1. I made it. The results are shown in Table 2.

Comparative Example 6 As shown in Table 2, the amount of PCMC and steam introduced into the first mixing nozzle 1 and the amount of steam introduced into the second mixing nozzle 11 were changed, respectively. Steam introduction amount in mixing nozzle 1 and second mixing nozzle 1
EXAMPLE 1 PC powder was obtained using the apparatus shown in FIG. 1 in the same manner as in Example 1, except that the amount of steam introduced in Example 1 was outside the limited range of the present invention. However, by changing the length of the pipe 10 connecting the first mixing nozzle 1 and the second mixing nozzle 11, the residence time τ of the mixture was set to 0.01 seconds, the same as in Example 1. Table 2 shows the bulk density and residual MC amount of the obtained PC powder.

Comparative Examples 7 to 8 By changing the length of the pipe 10 connecting the first mixing nozzle 1 and the second mixing nozzle 11, the residence time τ of the mixture was set to the time shown in Table 2. PC powder was obtained in the same manner as in Example 1 using the apparatus shown in FIG. Table 2 shows the bulk density and residual MC amount of the obtained PC powder.

Comparative Example 9 As shown in Table 2, the amount of PCMC introduced into the first mixing nozzle 1 and the amount of steam introduced into the second mixing nozzle 11 were changed, and the amount of PCMC introduced into the first mixing nozzle 1 was changed. By changing the length of the pipe 10 connecting the second mixing nozzle 11 and the second mixing nozzle 11, the residence time τ of the mixture can be adjusted to 0, which is outside the limited range of the present invention.
．． In the same manner as in Example 1 except that the time was set to 0005 seconds,
PC powder was obtained using the apparatus shown in . Table 2 shows the bulk density and residual MC amount of the obtained PC powder.

[0031]

[Table 1]

[0032]

[Table 2]

As is clear from Table 1, Examples 1 to 16
The bulk density of each PC powder obtained in
g/cc). These values are based on the bulk density of PC powder obtained by the conventional method using one mixing nozzle, 0.05
- greater than 0.35 (g/cc). In addition, Example 1
The residual MC amount of each PC powder obtained in ~16 is 20~10
It is as low as 0wt-ppm. Furthermore, in Examples 1 to 16, the processing amount of the organic solvent solution (methylene chloride solution) of PC was 5
Despite the variation in the range of 0 to 900 kg/hr, PC powders were stably obtained in all Examples, and there was little change in properties between the obtained PC powders. On the other hand, in Comparative Examples 1 to 9, PC powder was not obtained (Comparative Example 3), methylene chloride (liquid) was also discharged together with the PC powder (Comparative Example 1), and the bulk density of the obtained PC powder was low (
Comparative Examples 2, 4, 5, 6, 8, and 9), the resulting PC
Although the bulk density of the powder is high, there are drawbacks such as a large amount of residual methylene chloride (Comparative Example 7).

[0034]

[Effects of the Invention] As explained above, according to the present invention,
A polycarbonate powder with a high bulk density and a small amount of residual solvent can be easily obtained, and the properties of the obtained polycarbonate powder change little even when the amount of the organic solvent solution of polycarbonate treated changes. Therefore, with the polycarbonate powder obtained according to the present invention, it is possible to improve the volumetric efficiency of processing equipment when performing post-processing such as drying, storage, granulation, and molding, and it is possible to stably perform post-processing. This makes it possible to improve the productivity of polycarbonate products.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an apparatus used to produce polycarbonate powder in Examples.

2 is an end view schematically showing the structure of a first mixing nozzle used in the apparatus shown in FIG. 1. FIG.

3 is an end view schematically showing the structure of a second mixing nozzle used in the apparatus shown in FIG. 1. FIG.

[Explanation of symbols]

1 First mixing nozzle 2 Spout port of the first mixing nozzle 3 First nozzle of the first mixing nozzle 4 Second nozzle of the first mixing nozzle 5 Mixing chamber of the first mixing nozzle 7 First mixing nozzle PCMC supply pipe 10 in
Piping 11 connecting the first mixing nozzle and the second mixing nozzle Second mixing nozzle 12 Spout port 13 of the second mixing nozzle First nozzle 14 of the second mixing nozzle Second nozzle of the second mixing nozzle 15 Mixing chamber 17 of the second mixing nozzle Steam supply pipe 20 in the second mixing nozzle
Piping 21 connecting the second mixing nozzle and the cyclone
Cyclone 22 condenser

Claims (3)

[Claims] Claim 1: The concentration of polycarbonate is 3 to 45% by weight.
An organic solvent solution of 1/20 to 1/8 times the weight of the organic solvent in this organic solvent solution is introduced into a mixing nozzle, and the mixture injected from this mixing nozzle is 0.001 After a residence time of ~1 second, a second mixture is obtained by mixing with steam in an amount of 1/200 to 1/1 times the weight of the organic solvent in the organic solvent solution, and the polycarbonate is powdered from this second mixture. A method for producing polycarbonate powder, the method comprising recovering polycarbonate powder as 2. The second mixture is obtained by introducing the mixture injected from the mixing nozzle into the second mixing nozzle through piping and introducing steam into the second mixing nozzle. A method for producing the polycarbonate powder described. 3. The method for producing polycarbonate powder according to claim 1 or 2, wherein a methylene chloride solution of polycarbonate is used as the organic solvent solution.