JPH08217871A - Production of aromatic polycarbonate - Google Patents

Abstract

PURPOSE: To obtain the subject high-quality polymer excellent in sealability in a high vacuum without any coloring by reacting an alkaline aqueous solution of an aromatic dihydroxy compound with phosgene and polymerizing the resultant prepolymer while freely dropping the prepolymer in a molten state from a perforated plate along guides. CONSTITUTION: An alkaline aqueous solution of an aromatic dihydroxy compound (e.g. bisphenol A) is reacted with phosgene to produce an aromatic polycarbonate prepolymer, which is then continuously fed and polymerized while freely dropping the prepolymer in a molten state from a perforated plate along guides. A part of the dropped polymer is then circulated and polymerized while freely dropping the part again from the perforated plate along the guides. The resultant aromatic polycarbonate is continuously taken out to afford the objective polymer.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing an aromatic polycarbonate.

[0002]

2. Description of the Related Art In recent years, aromatic polycarbonates have been widely used in many fields as engineering plastics having excellent heat resistance, impact resistance and transparency. As for the method for producing this aromatic polycarbonate, various polymerization methods have been conventionally studied. Among them, an interfacial polycondensation method in which an alkaline aqueous solution of an aromatic dihydroxy compound such as 2,2'-bis (4-hydroxyphenyl) propane (hereinafter referred to as bisphenol A) is reacted with phosgene in the presence of an organic solvent. Is known.
The organic solvent used in this method is a halogen-based organic solvent, for example, methylene chloride, chlorobenzene and the like are used, but especially methylene chloride is mainly used. But,
By this method, it is difficult to completely remove the organic solvent from the obtained polymer, and the residual halogen derived from the organic solvent causes mold corrosion and coloring, which has an unfavorable effect on the subsequent applications.

On the other hand, as a method for producing an aromatic polycarbonate from an aromatic dihydroxy compound and a diaryl carbonate, for example, bisphenol A and diphenyl carbonate are transesterified in a molten state, and the by-produced phenol is polymerized while being extracted. Polycondensation methods are known. Unlike the interfacial polycondensation method, the melt polycondensation method has the advantage of not using a solvent, but on the other hand, the viscosity of the polymer increases as the polymerization progresses, and it is possible to efficiently extract the by-produced phenol etc. from the system. There is an essential problem that it becomes difficult and it is difficult to raise the degree of polymerization.

Conventionally, various polymerization reactors have been known as a polymerization reactor for the melt polycondensation method for producing an aromatic polycarbonate. The method of using a tank type polymerization vessel equipped with a stirrer is generally widely known. However, the stirred tank type polymerization vessel has the advantages of high volumetric efficiency and simplicity, but although the polymerization can be efficiently proceeded on a small scale, on an industrial scale, the polymerization progresses as described above. There is a problem that it is difficult to efficiently extract the by-produced phenol out of the system, and it is difficult to increase the degree of polymerization.

That is, in a large-scale stirred tank type polymerization vessel, the ratio of the liquid volume to the evaporation area is usually larger than that in the small scale, and the so-called liquid depth is large. In this case, even if the degree of vacuum is increased to increase the degree of polymerization, the lower portion of the stirring tank will be polymerized at a substantially high pressure due to the differential pressure, and phenol and the like will not efficiently escape. is there.

In order to solve this problem, various measures have been taken to extract phenol and the like from a polymer having a high viscosity. For example, Japanese Patent Publication No. 50-19600 describes a screw type polymerization device having a vent portion, and Japanese Patent Publication No. 53-5718 discloses a thin film evaporation type reactor such as a screw evaporator or a centrifugal thin film evaporator. In addition, Japanese Patent Laid-Open No. 2-153923 discloses a method of using a thin film type evaporator and a horizontal stirring polymerization tank in combination. The disadvantage that these polymerization vessels have in common, including the stirring tank type, is that there is a rotation drive part in the polymerization vessel body,
When the polymerization is carried out under a high vacuum, the driving part cannot be completely sealed, so that a slight amount of oxygen cannot be prevented from leaking in, and coloring of the product cannot be avoided. When a seal liquid is used to prevent oxygen from leaking in, it is unavoidable that the seal liquid is mixed in, and deterioration of the product quality is unavoidable. Further, even when the sealing property at the beginning of operation is high, the sealing property is deteriorated during continuous operation for a long time, which causes serious problems in maintenance.

By the way, the main body does not have a rotary drive portion,
The method of polymerizing while dropping from a perforated plate is known as a method for producing a resin other than aromatic polycarbonate. For example, U.S. Pat. No. 3,110,547 discloses a method in which a polyester is dropped into a thread in a vacuum to produce a polyester having a desired molecular weight. In the specification, since the quality of polyester is deteriorated when the dropped yarn is circulated again, the polymerization is completed in one pass without being circulated. However, many drawbacks have been pointed out for such methods. For example, Japanese Patent Publication 4
Japanese Unexamined Patent Publication No. 8-8355 discloses the following regarding a method of polycondensing while spinning from a spinneret in a vacuum. If a fiber having a sufficiently high fiber-forming ability is not supplied, the yarn during polymerization is easily cut in the reactor, and the quality variation of the polycondensate becomes severe.
The low molecular weight condensate scattered from the yarn contaminates the die surface,
It becomes difficult for the thread to be ejected directly below from the spinneret, and when it comes into contact with it, it breaks or converges and flows down into a thick fibrous shape that interferes with the reaction. The monitoring window tends to become cloudy and difficult to monitor, so that it is easy to lose the time to replace the mouthpiece. In this publication, as a method for producing polyester and polyamide, a method is described in which a polymer is polymerized while flowing down a polymer along a porous body arranged vertically in a reaction vessel, but an aromatic polycarbonate is completely described. Not not.

As a method of removing the monomer remaining in the polymerization product, which is not a polymerization method, a method of dropping a lactam heavy synthetic organism into a thread form from a perforated plate is described in US Pat.
719776. However, many drawbacks have been pointed out in this method as well. For example, in JP-A-53-17569, US Pat.
The following inconveniences have been pointed out for the method of 719776. If the evaporation of the volatiles is small, the filamentous material can be formed, but if the evaporation is large, the filamentous material is foamed, and smooth operation is difficult. It can only be applied to materials with a relatively narrow range of specific viscosities to form filaments. When an inert gas or the like is introduced into the tower, neighboring filaments come into contact with each other due to the turbulence of the air flow. In order to solve these problems, JP-A-53-17569 discloses a method in which a linear support is provided in the longitudinal direction and a highly viscous material is flowed down along the support, polyethylene terephthalate, polybutylene. It has been proposed for polyesters such as terephthalate and polyamides such as nylon 6 and nylon 66, but aromatic polycarbonate is not described.

In Japanese Patent Publication No. 14127/1992, there are two methods of continuous polycondensation of polyester, one of which is polycondensation while dropping the other, namely, a method of spinning from a spinneret and a method of polymerizing while extruding a film from a slit. It is described that it is difficult for any of these methods to proceed with polycondensation. Further, the publication proposes a method in which a thin film is held between at least two wires from a slit-shaped supply port, and the polycondensation is continuously carried out by moving the film in one direction in the longitudinal direction. In this publication, of course, nothing is mentioned about aromatic polycarbonate.

As described above, the method of polymerizing while dropping it from the perforated plate is known as a method for producing polyester or polyamide but not as a method for producing aromatic polycarbonate. As a method for producing polyester or polyamide, the method of polymerizing while dropping it has been pointed out to have many drawbacks such as pore clogging.

Further, a production method in which an aromatic polycarbonate prepolymer is produced by an interfacial polycondensation method in which an alkaline aqueous solution of an aromatic dihydroxy compound is reacted with phosgene, and the obtained aromatic polycarbonate prepolymer is polymerized while being dropped from a porous plate. Is not known at all.

[0012]

The present invention is to produce an aromatic polycarbonate prepolymer by an interfacial polycondensation method, and to produce an aromatic polycarbonate prepolymer by a melt polycondensation method.
An object of the present invention is to provide a method for producing a high-quality aromatic polycarbonate with no residual solvent and no coloring at a high polymerization rate, which is a device that has excellent sealing properties under high vacuum and is easy to maintain, and is stable for a long period of time with no residual solvent. And

[0013]

As a result of intensive studies to solve the above problems, the present inventors have found that the object can be achieved by carrying out polymerization using a specific production method. The invention was completed. That is, according to the present invention, (1) an alkaline aqueous solution of an aromatic dihydroxy compound is allowed to react with phosgene to produce an aromatic polycarbonate prepolymer, and the obtained aromatic prepolymer prepolymer is melted from a porous plate to a guide. A method for producing an aromatic polycarbonate, characterized in that it is polymerized while being dropped, (2) An aromatic polycarbonate prepolymer is produced by reacting an alkaline aqueous solution of an aromatic dihydroxy compound with phosgene, and the obtained aromatic polycarbonate The prepolymer is polymerized in a molten state while being dropped along the guide from the perforated plate, and a part or all of the dropped polymer is circulated to be polymerized while being dropped again along the guide from the perforated plate. A method for producing an aromatic polycarbonate, characterized in that (3) aromatic dihydride Aromatic aqueous solution of xy compound is reacted with phosgene to produce aromatic polycarbonate prepolymer, and the obtained aromatic polycarbonate prepolymer is continuously supplied, and polymerized while falling along the guide from the perforated plate in the molten state. Then, a part of the dropped polymer is circulated and polymerized while being dropped again along the guide from the perforated plate, and a method for producing an aromatic polycarbonate characterized by continuously extracting an aromatic polycarbonate, (4) Prepolymerization in which an alkaline aqueous solution of an aromatic dihydroxy compound is reacted with phosgene to produce an aromatic polycarbonate prepolymer, and the obtained aromatic polycarbonate prepolymer is polymerized in a molten state using a stirring tank type polymerization device. Process and the polymerization intermediate obtained in the pre-polymerization process in the molten state from the porous plate to the guide A method for producing an aromatic polycarbonate, characterized by comprising a post-polymerization step in which the polymerization is carried out while dropping it, and (5) the post-polymerization step guides the polymerization intermediate obtained in the pre-polymerization step from a perforated plate in a molten state. Aromatic polycarbonate according to item (4), which is a method of polymerizing while dropping along with the above, and circulating a part or all of the dropped polymer along the guide again from the above-mentioned perforated plate while dropping along with the guide. Manufacturing method of
(6) In the post-polymerization step, the polymerization intermediate obtained in the pre-polymerization step is continuously supplied and polymerized in a molten state while dropping along the guide from the porous plate, and a part of the dropped polymer. (4) A method for producing an aromatic polycarbonate according to (4), wherein the aromatic polycarbonate is continuously extracted from the porous plate by circulating it and dropping the aromatic polycarbonate along the guide again. Prepolymerization step of reacting the alkaline aqueous solution with phosgene to produce an aromatic polycarbonate prepolymer, and polymerizing the obtained aromatic prepolymer prepolymer in a molten state using a stirring tank type polymerization device, and a prepolymerization step An intermediate polymerization step in which the polymerization intermediate obtained in step 1 is polymerized in a molten state while dropping it in a wet-wall type, and the polymerization intermediate obtained in the intermediate polymerization step is guided from a porous plate. A method for producing an aromatic polycarbonate, characterized by comprising a post-polymerization step of polymerizing while dropping along with (8) a post-polymerization step, in which a polymerization intermediate obtained in the intermediate polymerization step is melted to form a perforated plate. Is a method of polymerizing while dropping along the guide from the perforated plate, and part or all of the dropped polymer is circulated and polymerized while dropping along the guide again from the perforated plate (7).
The method for producing an aromatic polycarbonate described in (9), in which the post-polymerization step continuously supplies the polymerization intermediate obtained in the intermediate polymerization step, and polymerizes the molten intermediate while dropping it from the porous plate along the guide. The method for producing an aromatic polycarbonate according to (7) is a method in which a part of the dropped polymer is circulated and polymerized while being dropped along the guide again from the perforated plate to continuously withdraw the aromatic polycarbonate. Method, (10) The height of dropping from the perforated plate along the guide is 0.3 m or more, (1), (2),
(3), (4), (5), (6), (7), (8) or (9) the method for producing an aromatic polycarbonate,
(11) The number average molecular weight of the aromatic polycarbonate prepolymer obtained by reacting an alkaline aqueous solution of an aromatic dihydroxy compound with phosgene is in the range of 300 to 20,000, (1), (2), (3), (4),
(5), (6), (7), (8) or (9) The method for producing an aromatic polycarbonate is provided.

As described above, in the conventional interfacial polycondensation method, the halogen derived from the organic solvent remaining in the obtained polymer causes mold corrosion and coloration. However, according to the manufacturing method of the present invention, the device is excellent in sealing property under high vacuum and is easy to maintain, and is stable for a long period of time.
A high-quality aromatic polycarbonate having no residual solvent and no coloring can be produced at a high polymerization rate.
Although the reason for this is not clear, the aromatic polycarbonate prepolymer obtained by the interfacial polycondensation method is a by-produced aromatic monohydroxy compound when polymerized in a molten state while being dropped along the guide from the porous plate. Since the remaining organic solvent can be extracted efficiently, it is presumed that the organic solvent that causes mold corrosion or coloring does not remain.

By the way, various types of polymerizers which do not have a rotational driving portion in the main body for carrying out melt polycondensation are known as polymerizers for polymerizing resins other than polycarbonate. Since the melt polycondensation reaction is significantly different from the melt polycondensation reaction of polyesters and polyamides, it is difficult to apply a high-viscosity polymerizer for the production of polyamides or polyesters to the method of manufacturing aromatic polycarbonates. The major differences between polyamides and polyesters and aromatic polycarbonates are as follows. First, the melt viscosity, which is an important factor in the design of melt polycondensation polymerization reactors, is extremely high in the case of aromatic polycarbonate. That is, the melt viscosity of polyamides and polyesters in the latter stage of polymerization is usually several hundred to several thousand poises under the conditions of the polymerization temperature, and rarely exceeds 3000 poises. Reach 10,000 poise. Secondly, the melt polycondensation of polyamide, polyester and aromatic polycarbonate is an equilibrium reaction, but the equilibrium constants are greatly different. Normally, the equilibrium constant of polyamide is 10 ² order and that of polyester is about 1, whereas the equilibrium constant of aromatic polycarbonate is 10 ^-1.
It is on the order, and even in the same polycondensation reaction, the equilibrium constant is extremely small in the case of aromatic polycarbonate. The fact that the equilibrium constant is small means that the polymerization does not proceed unless the by-product is removed more efficiently from the outside of the system. Therefore,
The reaction of the aromatic polycarbonate needs to extract the by-product from the system much more efficiently than the reaction of the polyester or the polyamide, and this is extremely difficult for the aromatic polycarbonate having a high melt viscosity.

However, according to the present invention, it is surprisingly found that aromatic polycarbonate can be polymerized by spinning conventional polyesters and polyamides without causing any problems in the method of polymerizing while dropping. It was That is, since there is no variation in quality due to the cutting of the yarn, a high quality aromatic polycarbonate can be stably produced. Furthermore, since the spinneret is not contaminated by the low molecular weight condensate at all, it does not hinder the yarn from being ejected directly below, and does not stop the operation for exchanging the spinneret. Therefore, it is possible to operate stably for a very long period of time.

The reason for these apparent differences between the phenomena in the melt polycondensation reaction of aromatic polycarbonates and those in the reaction of polyesters and polyamides is not clear. However, regarding the fact that the contamination of the die does not occur at all, it is possible that the low molecular weight condensate is effectively washed by the by-produced phenols in the reaction of the aromatic polycarbonate, and water and ethylene glycol are produced as by-products. It is speculated that this may be because it is fundamentally different from the reaction of polyamide or polyester, but such an effect could not be predicted at all from the polymerization reaction of polyester or polyamide.

Further, the method of polymerizing while dropping from the perforated plate along the guide according to the present invention does not necessarily need to have a rotation driving part in the gas phase part of the polymerization vessel, and has sealing property under high vacuum. It has been revealed that it is possible to produce a high quality aromatic polycarbonate which is excellent, easy to maintain, and colorless and transparent. That is, by using the production method of the present invention, all of the problems as described above, which have occurred in the conventional melt polycondensation of aromatic polycarbonate, can be solved.

In the present invention, a method for producing an aromatic polycarbonate using a single polymerization vessel in which an aromatic polycarbonate prepolymer by the interfacial polycondensation method is dropped from a porous plate along a guide to polymerize Aromatic polycarbonate is produced by combining multiple polymerization methods by using a plurality of polymerization vessels that polymerize while dropping from a plate along a guide, a method of dropping from a porous plate along a guide and polymerizing, and another polymerization method. A method for producing a group polycarbonate is possible.

Preferred embodiments of the method of polymerizing while dropping from the porous plate along the guide and the method of combining with other methods are a method of using a stirred tank type polymerization device in the prepolymerization step and a method of using the porous plate in the postpolymerization step. There is a method of combining a polymerization vessel that causes polymerization while dropping along a guide. By this method, high quality aromatic polycarbonate can be efficiently produced. Since it is not necessary to carry out the prepolymerization step in a high vacuum, it is possible to perform polymerization in a high volume efficiency without impairing the quality even in a stirred tank type polymerizer. In the post-polymerization step for further increasing the degree of polymerization, a method of polymerizing while dropping along the guide is particularly advantageous.
By combining these polymerization methods, a high quality aromatic polycarbonate can be efficiently produced.

In the pre-polymerization step, a method of polymerizing using a stirred tank type polymerizer, in the intermediate polymerization step, a method of polymerizing while dropping by a painted wall method, and in the post-polymerization step, dropping from a perforated plate along a guide is performed. However, a method of combining polymerization methods is also a preferred embodiment of the present invention. It is not necessary to carry out the pre-polymerization step in the first half of the polymerization in a high vacuum in general, and as described above, the polymerization can be performed with high volume efficiency without impairing the quality even in a stirred tank type polymerization device. In the intermediate polymerization process where the degree of polymerization of the polymer does not increase so much, the method of polymerizing while dropping it in a painted wall system allows a large heat transfer area to efficiently provide latent heat of vaporization of aromatic monohydroxy compounds and residual solvents. It is possible and advantageous. In the post-polymerization step for further increasing the degree of polymerization, a method of polymerizing while dropping along the guide is particularly advantageous.
That is, in the method of dropping by a wet wall method, since the polymer falls on the inner wall of the tube, when the viscosity of the falling polymer is high, the film thickness becomes thick and the area for evaporating the aromatic monohydroxy compound etc. decreases. In the method of polymerizing while dropping along the guide, such a disadvantage does not occur even when the viscosity is high, and the fact that the film thickness increases rather increases the evaporation area. By combining these polymerization methods, a high quality aromatic polycarbonate can be efficiently produced.

The present invention will be described in detail below. In the present invention, the aromatic polycarbonate prepolymer can be easily produced by reacting an aromatic dihydroxy compound with phosgene in the presence of a known acid acceptor and molecular weight modifier in an organic solvent such as methylene chloride. You can The aromatic dihydroxy compound in the present invention is a compound represented by HO-Ar-OH (wherein Ar represents a divalent aromatic group).

The aromatic group Ar is preferably, for example, -A.
A divalent aromatic group represented by r ¹ -Y-Ar ^2- (wherein Ar ¹ and Ar ² each independently have 5 to 7 carbon atoms).
Represents a divalent carbocyclic or heterocyclic aromatic group having 0, and Y represents a divalent alkane group having 1 to 30 carbon atoms. ). In the divalent aromatic groups Ar ¹ and Ar ² , one or more hydrogen atoms are other substituents that do not adversely affect the reaction, for example, a halogen atom, an alkyl group having 1 to 10 carbon atoms, and 1 to 10 carbon atoms. It may be substituted with 10 alkoxy groups, phenyl groups, phenoxy groups, vinyl groups, cyano groups, ester groups, amide groups, nitro groups and the like.

Specific preferred examples of the heterocyclic aromatic group include aromatic groups having one or more ring-forming nitrogen atoms, oxygen atoms or sulfur atoms. The divalent aromatic groups Ar ¹ and Ar ² represent groups such as substituted or unsubstituted phenylene, substituted or unsubstituted biphenylene, and substituted or unsubstituted pyridylene. The substituents here are as described above.

The divalent alkane group Y is represented by the following chemical formula 1, for example.
Is an organic group represented by.

[0026]

Embedded image

(In the formula, R ¹ , R ² , R ³ and R ⁴ are each independently hydrogen, an alkyl group having 1 to 10 carbon atoms, and 1 to 1 carbon atoms.
10 alkoxy groups, cycloalkyl groups having 5 to 10 ring carbon atoms, carbocyclic aromatic groups having 5 to 10 ring carbon atoms,
It represents a carbocyclic aralkyl group having 6 to 10 carbon atoms. k is 3
Represents an integer from 1 to 11 and R ⁵ and R ⁶ are individually selected for each X and independently of each other hydrogen or 1 carbon atom.
~ 6 represents an alkyl group, X represents carbon. Also,
In R ¹ , R ² , R ³ , R ⁴ , R ⁵ , and R ⁶ , other substituents such as a halogen atom and an alkyl group having 1 to 10 carbon atoms are used as long as one or more hydrogen atoms do not adversely affect the reaction. It may be substituted with a group, an alkoxy group having 1 to 10 carbon atoms, a phenyl group, a phenoxy group, a vinyl group, a cyano group, an ester group, an amide group, a nitro group or the like. ) Examples of such a divalent aromatic group Ar include those represented by the following chemical formula 2.

[0028]

Embedded image

(In the formula, R ⁷ and R ⁸ are each independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, or a cycloalkyl group having 5 to 10 carbon atoms in the ring. An alkyl group or a phenyl group, m and n
Is an integer of 1 to 4, and when m is 2 to 4, each R ⁷ may be the same or different, and n is 2 to 4
In the case of, each R ⁸ may be the same or different. ) Furthermore, a divalent aromatic group Ar is, -Ar ¹ -Z-Ar ² -
It may be shown by.

(In the formula, Ar ¹ and Ar ² are as described above,
Z is a single bond or -O-, -CO-, -S-, -SO.
_{2 -, - SO -, -} COO -, - CON (R 1) - represents a divalent group, such as. However, R ¹ is as described above. ) Examples of such a divalent aromatic group Ar include those represented by the following chemical formula 3.

[0031]

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(In the formula, R ⁷ , R ⁸ , m and n are as described above.) Further, specific examples of the divalent aromatic group Ar include substituted or unsubstituted phenylene, substituted or unsubstituted phenylene. Naphthylene,
Substituted or unsubstituted pyridylene and the like are also included. The substituents here are as described above. The aromatic dihydroxy compound used in the present invention may be a single type or two or more types. A typical example of the aromatic dihydroxy compound is bisphenol A. In the present invention, it is also possible to simultaneously use a trifunctional or higher polyfunctional compound for the aromatic dihydroxy compound.

The molecular weight adjusting agent in the present invention is not particularly limited, but various kinds which can be usually used for aromatic polycarbonate can be used, and among them, monophenol is preferable. Examples of the monophenol include phenol, on-butylphenol, and m-n.
-Butylphenol, pn-butylphenol, o-
Isobutylphenol, m-isobutylphenol, p
-Isobutylphenol, ot-butylphenol,
m-t-butylphenol, p-t-butylphenol, on-pentylphenol, m-n-pentylphenol, p-n-pentylphenol, on-hexylphenol, m-n-hexylphenol, p-n
-Hexylphenol, pt-octylphenol,
o-cyclohexylphenol, m-cyclohexylphenol, p-cyclohexylphenol, o-phenylphenol, m-phenylphenol, p-phenylphenol, on-nonylphenol, mn-nonylphenol, pn-nonylphenol, o- Cumylphenol, m-cumylphenol, p-cumylphenol, o-naphthylphenol, m-naphthylphenol, p-naphthylphenol, 2,5-di-t-butylphenol, 2,4-di-t-butylphenol , 3,
Examples include 5-di-t-butylphenol, 2,5-dicumylphenol, 3,5-dicumylphenol, p-cresol, bromophenol, tribromophenol and the like.

In addition, the one represented by the following formula 4 is also included.

[0035]

[Chemical 4]

The above monophenols may be used alone or in combination of two or more.
Among these, pt-butylphenol, p-cumylphenol, p-phenylphenol and the like are preferably used. In addition to these aromatic monohydroxy compounds, other molecular weight regulators such as methanol,
Monohydric alcohols such as ethanol: Methylchloroformates, cyclohexylchloroformates and other haloformates: Methyl mercaptans, ethyl mercaptans and other monohydric thiols: Methyl chlorothioformates,
Monovalent halothioformates such as ethyl chlorothioformate: It is also effective to use monocarboxylic acids such as acetic acid, propionic acid, benzoic acid, sodium acetate, acetic anhydride, acetyl chloride, and propionyl chloride, and their derivatives together. Is. Further, it is also effective to add 5 mol% or less of a dibasic acid or a reactive derivative thereof to the aromatic dihydroxy compound and to react them.

The dibasic acid and its reactive derivative may be any of aliphatic, aromatic and alicyclic compounds, and specific examples thereof include terephthalic acid, isophthalic acid, phthalic acid and naphthalene-1. , 5-dicarboxylic acid, diphenyl-
Dibasic acids such as 2,2-dicarboxylic acid, cis-1,2-cyclohexanedicarboxylic acid, oxalic acid, succinic acid, sebacic acid, adipic acid, maleic acid and fumaric acid, and alkali metal salts of these dibasic acids. , Alkaline earth metal salts,
Examples thereof include amine salts, acid halides and aryl esters.

In addition, a compound having three or more functional groups can be used as a branching agent. Among them, for example,
1,1,1-tris (4-hydroxyphenyl) ethane, α, α ′, α ″ -tris (4-hydroxyphenyl) -1,3,5-triisopropylbenzene, 1-
[Α-Methyl-α- (4′-hydroxyphenyl) ethyl] -4- [α ′, α′-bis (4 ″ -hydroxyphenyl) ethyl] benzene, phloroglysin, trimellitic acid, isatin bis (o-cresol) ) Etc. can be used.

The organic solvent used in the present invention can be appropriately selected according to various situations. For example, methylene chloride (dichloromethane), chloroform, 1,1-dichloroethane, 1,2-dichloroethane, 1,1,1-
Trichloroethane, 1,1,2-trichloroethane,
1,1,1,2-tetrachloroethane, 1,1,2,2
-Chlorine hydrocarbons such as tetrachloroethane and pentachloroethane, diphenyl ether, halogenated diphenyl ether, diphenyl sulfone, acetophenone, benzophenone, polyphenyl ether, chlorobenzene,
Examples thereof include aromatic compounds such as dichlorobenzene and methylnaphthalene, chlorofluorohydrocarbons, cyclohexane, cycloalkanes such as tricyclo (5.2.1.0) -decane, cyclooctane and cyclodecane. These organic solvents may be used alone or in combination of two or more. Of these, methylene chloride is preferably used.

As the alkali source of the alkaline aqueous solution used in the present invention, an alkali metal hydroxide is used. For example, sodium hydroxide, potassium hydroxide, lithium hydroxide, cesium hydroxide and the like can be mentioned, of which sodium hydroxide and potassium hydroxide are preferably used. The interfacial polycondensation reaction and the melt polycondensation reaction in the present invention can be carried out without adding a catalyst, but in order to increase the polymerization rate, they are carried out in the presence of a catalyst, if necessary. The polymerization catalyst is not particularly limited as long as it is used in this field, but hydroxides of alkali metals and alkaline earth metals such as lithium hydroxide, sodium hydroxide, potassium hydroxide and calcium hydroxide. Alkali metal salts, alkaline earth metal salts, quaternary ammonium salts of hydrides of boron and aluminum such as lithium aluminum hydride, sodium borohydride, tetramethylammonium borohydride; lithium hydride, sodium hydride ,
Hydrogen compounds of alkali metals and alkaline earth metals such as calcium hydride; alkali metal and alkaline earth metal alkoxides such as lithium methoxide, sodium ethoxide, calcium methoxide; lithium phenoxide, sodium phenoxide, magnesium phenoxide, LiO-Ar-OLi, NaO-Ar-ON
a (R is an aryl group) such as alkali metal and alkaline earth metal aryloxides; lithium acetate, calcium acetate, sodium benzoate and other alkali metal and alkaline earth metal organic acid salts; zinc oxide, zinc acetate,
Zinc compounds such as zinc phenoxide; boric oxide, boric acid, sodium borate, trimethyl borate, tributyl borate, triphenyl borate, (R ¹ R ² R ³ R ⁴ ) NB (R ¹ R
² R ³ R ⁴ ) or (R ¹ R ² R ³ R ⁴ ) PB (R ¹ R ² R ³ R ⁴ ) or an ammonium borate or a phosphonium borate (R ¹ , R ² , R ³ , R ⁴ is a compound of boron (as described above in Chemical formula 3); a compound of silicon such as silicon oxide, sodium silicate, tetraalkyl silicon, tetraaryl silicon, diphenyl-ethyl-ethoxy silicon; germanium oxide, tetrachloride Compounds of germanium such as germanium, germanium ethoxide, and germanium phenoxide; tin compounds bonded with an alkoxy group or aryloxy group such as tin oxide, dialkyltin oxide, dialkyltin carboxylate, tin acetate, ethyltin tributoxide, organotin compounds Compounds of tin such as lead oxide, lead acetate, lead carbonate, basic carbonate, lead and organic lead alco Compounds of lead such as xides or aryloxides; onium compounds such as quaternary ammonium salts, quaternary phosphonium salts, quaternary arsonium salts;
Antimony compounds such as antimony oxide and antimony acetate; Manganese compounds such as manganese acetate, manganese carbonate and manganese borate; Titanium compounds such as titanium oxide, titanium alkoxides or aryloxides; zirconium acetate, zirconium oxide, zirconium Examples thereof include catalysts such as alkoxides or aryloxides, zirconium compounds such as zirconium acetylacetone, and the like.

When a catalyst is used, these catalysts may be used alone or in combination of two or more. The amount of these catalysts used is usually selected from the range of 10 ^-8 to 1% by weight, preferably 10 ^-7 to 10 ^-1 % by weight, based on the starting aromatic dihydroxy compound. The aromatic polycarbonate prepolymer in the present invention can be produced by the interfacial polycondensation method which is conventionally carried out using the above raw materials. First, the aromatic dihydroxy compound is dissolved in an aqueous solution of an alkali metal hydroxide to prepare an alkaline hydroxide aqueous solution of the aromatic dihydroxy compound. Next, the organic solvent is added to an alkali hydroxide aqueous solution of an aromatic dihydroxy compound to prepare a mixed solution. At this time, a molecular weight modifier may be added if necessary. An excess amount of phosgene is blown into the mixed solution to react with each other to form an aromatic polycarbonate prepolymer, which is an emulsion containing an organic phase containing the aromatic polycarbonate prepolymer and an aqueous phase containing an aqueous solution of an alkali metal or the like. A reaction solution is obtained. The reaction solution is allowed to stand to separate into two phases, an organic phase and an aqueous phase. As a reactor for carrying out this interfacial polycondensation method, a tank reactor equipped with a stirrer is usually used. When separating the organic phase containing the aromatic polycarbonate prepolymer, this reactor may be used as a batch system, or a plurality of reactors may be connected in series to perform continuous separation. The separated organic phase is optionally washed with an alkali, an acid and a water to obtain a solution of the obtained aromatic polycarbonate prepolymer in an organic solvent. By evaporating and removing the organic solvent from this solution, an aromatic polycarbonate prepolymer powder is obtained. The end of the aromatic polycarbonate prepolymer thus obtained is usually a carbonate end of an alkyl group / aromatic group. A methyl group, an ethyl group, a butyl group and a phenyl group are preferable from the viewpoints of easiness of reaction, recovery, monomer cost and the like. These may be used alone or in combination of two or more.

As another method for producing the aromatic polycarbonate prepolymer, transesterification of the aromatic dihydroxy compound and the carbonate compound may be used. Examples of carbonate compounds that can be used in the present invention include dimethyl carbonate, diethyl carbonate, and diphenyl carbonate. In the transesterification method, a known catalyst can be used to accelerate the reaction. Examples of such catalysts include simple substances of alkali metals or alkaline earth metals, oxides, hydroxides, amide compounds, alcoholates, phenolates, basic metal oxides such as ZnO, PbO, Sb ₂ O ₃ and organic compounds. Titanium compound, soluble manganese compound, Ca, Mg, Zn, Pb, Sn, Mn, Cd, Co
A combination of an acetate salt or a nitrogen-containing basic compound and a boron compound, a nitrogen-containing basic compound and an alkali metal compound or an alkaline earth metal compound, a nitrogen-containing basic compound and a boron compound and an alkali metal compound or an alkaline earth metal compound A system catalyst etc. are mentioned.

The number average molecular weight of the aromatic polycarbonate prepolymer thus obtained is usually 300 to 2000.
0. In the present invention, the aromatic polycarbonate prepolymer obtained by the above method is polymerized in a molten state while being dropped along the guide from the perforated plate to produce an aromatic polycarbonate.

The shape of the holes in the perforated plate in the present invention is not particularly limited, and is usually selected from a circular shape, an oval shape, a triangular shape, a slit shape, a polygonal shape, a star shape and the like. Cross-sectional area of the hole is usually 0.01～100Cm ^2, preferably 0.05～10Cm ^2, particularly preferably from 0.1 to 5 cm ^2. The distance between the holes is usually 1 to 500 mm, preferably 5 to 100 mm in terms of the distance between the centers of the holes.

In the present invention, the guide means a material having a very large ratio of the length in the direction perpendicular to the cross section to the average length of the outer circumference of the cross section. The ratio is not particularly limited, but is usually in the range of 10 to 1,000,000, preferably in the range of 50 to 100,000. The shape of the cross section is not particularly limited and is usually selected from the shapes such as a circle, an ellipse, a triangle, a quadrangle, a polygon, and a star. The cross-sectional shape may be the same or different in the length direction. Further, the guide may be hollow. The guide may be a single piece such as a wire,
It may be a combination of a plurality of methods such as twisting. The surface of the guide may be smooth or uneven, and may partially have protrusions or the like. There is no particular limitation on the material of the guide, but usually, a metal such as stainless steel, carbon steel, hastelloy, nickel, titanium, chrome, or other alloy, or a polymer material with high heat resistance is used. Selected from the inside. Also, the surface of the wire is
Various treatments such as plating, lining, passivation treatment, acid cleaning, and phenol cleaning may be performed as necessary.

The guide may be directly connected to the hole of the perforated plate or may be separated from the hole. Preferred specific examples include those in which each guide penetrates and is connected near the center of each hole of the perforated plate, and those in which the guide is connected to the outer peripheral portion of each hole of the perforated plate. The lower end of the guide is
It may be in contact with the bottom liquid surface of the polymerization vessel or may be separated therefrom.

As a method of dropping the melt of the aromatic polycarbonate prepolymer along the guide through the porous plate, a method of dropping it by a liquid head or its own weight, or by applying pressure using a pump or the like,
Examples thereof include a method of extruding the prepolymer melt from a porous plate. The number of pores is not particularly limited, and varies depending on the conditions such as reaction temperature and pressure, the amount of catalyst, the range of molecular weight to be polymerized, etc., but usually the polymer is, for example, 100 kg / h.
r 10 to 10 ⁵ holes are required for manufacturing.

After passing through the hole, drop along the guide.
The height to be applied is preferably 0.3 to 50 m, and
It is preferably 0.5 to 20 m. Flow rate through the hole
Also depends on the molecular weight of the aromatic polycarbonate
Is usually 10 per hole^-Four-10^FourLiter / h
r, preferably 10^-2-10 ²Liter / hr, especially good
It is preferably in the range of 0.1 to 50 liter / hr.

The time required for dropping along the guide is not particularly limited, but is usually in the range of 0.01 seconds to 10 hours. In the present invention, the polymer after dropping along the guide may be dropped as it is to the liquid reservoir,
Alternatively, it may be forcibly taken into the liquid reservoir with a take-up device or the like. Further, the polymerized product after being dropped may be extracted as it is, but it is also a preferable method to circulate the polymerized product and polymerize it by dropping it again along the guide. In this case, the residence time can be lengthened according to the reaction time required for the polycondensation reaction in the liquid reservoir portion after being dropped, the circulation line, or the like. In addition, since a new liquid surface area that can be formed in a unit time can be made large by performing circulation while dropping along the guide, it becomes easy to sufficiently proceed the polymerization to a desired molecular weight.

In a preferred embodiment of the present invention, the aromatic polycarbonate prepolymer is continuously supplied and polymerized in a molten state while being dropped along the guide from the perforated plate, and a part of the dropped polymer is circulated. Then, the aromatic polycarbonate is continuously extracted by polymerizing while dropping along the guide again. At this time, it is one of the great advantages of the present invention that the porous plate can be stably operated for a long period of time without being contaminated with a low condensate.

In the present invention, when the aromatic polycarbonate prepolymer is reacted to produce an aromatic polycarbonate, the reaction temperature is usually 50 to 350 ° C.
It is preferably selected in the temperature range of 100 to 290 ° C.
Aromatic monohydroxy compounds are produced as the reaction progresses, but the reaction rate can be increased by removing them from the reaction system. Therefore, by introducing an inert gas such as nitrogen, argon, helium, carbon dioxide or a lower hydrocarbon gas that does not adversely affect the reaction, the produced aromatic monohydroxy compound or residual solvent is added to these gases. A method of removing by entrainment, a method of performing the reaction under reduced pressure, and the like are preferably used. The preferable reaction pressure varies depending on the molecular weight of the aromatic polycarbonate to be produced, and when the number average molecular weight is 1,000 or less, it is 5
The range of 0 mmHg to normal pressure is preferable, and the number average molecular weight is 1
In the range of 000 to 2000, 3 mmHg to 80 mmH
The range of g is preferable, and when the number average molecular weight is 2000 or more, 20 mmHg or less, particularly 10 mmHg or less is preferable.

A particularly preferred method is a method of carrying out the reaction under reduced pressure and while introducing the above-mentioned inert gas.
By this method, there is no inconvenience that neighboring yarns come into contact with each other due to turbulence of the air flow, and the degree of polymerization can be efficiently increased. The number average molecular weight of the aromatic polycarbonate obtained by the method of the present invention is usually 500 to 1
It is in the range of 00000, preferably 500 to 3000
It is in the range of 0.

In the present invention, the melt of the aromatic polycarbonate prepolymer means a state in which the aromatic polycarbonate prepolymer is melted in a heated state and becomes uniform. The prepolymer melt can be obtained by heating the aromatic polycarbonate prepolymer to 150 to 250 ° C. The polymerization intermediate means a polycondensate having a lower molecular weight than the aromatic polycarbonate finally produced in the present invention by polymerizing the melt of the aromatic polycarbonate prepolymer by the method of the present invention. That is, the molecular weight range of the polymerization intermediate defined in the present invention varies depending on the molecular weight of the aromatic polycarbonate finally produced. For example, when the number average molecular weight of the aromatic polycarbonate to be produced is 10,000, the molecular weight range of the polymerization intermediate is less than 10,000, and when the number average molecular weight of the aromatic polycarbonate to be produced is 20,000, the molecular weight range of the polymerization intermediate is Is less than 20,000.

An example of a preferable polymerization vessel used in the present invention is
A description will be given based on the figure. 1 and 2 are specific examples of a polymerization vessel for achieving the method of the present invention. In FIG. 1, the melt of the aromatic polycarbonate prepolymer is supplied from the raw material supply port 1, is introduced into the inside of the polymerization vessel through the porous plate 3, and is dropped along the guide 4. The inside of the polymerization vessel is controlled to a predetermined pressure, such as aromatic monohydroxy compounds and residual solvent distilled from the melt, and an inert gas such as nitrogen introduced from the gas supply port 5 as necessary. Is discharged from the vent port 6. Emission pump 8 for polymer
Is discharged from the discharge port 9. The polymerizer main body 10 and the like are heated by a heater or a jacket and kept warm.

In FIG. 2, the melt of the aromatic polycarbonate prepolymer is supplied to the circulation line 2 through the raw material supply port 1, passes through the porous plate 3 and is introduced into the inside of the polymerization vessel, and falls along the guide 4. . The inside of the polymerization vessel is controlled to a predetermined pressure, such as aromatic monohydroxy compounds and residual solvent distilled from the melt, and an inert gas such as nitrogen introduced from the gas supply port 5 as necessary. Is discharged from the vent port 6. The melt that has reached the bottom of the polymerizer is supplied again from the porous plate 3 to the inside of the polymerizer through a circulation line 2 equipped with a circulation pump 7. The polymer having reached the predetermined molecular weight is discharged from the discharge port 9 by the discharge pump 8. The main body 10 of the polymerization vessel, the circulation line 2 and the like are heated and kept warm by a heater or a jacket.

When the polymerizer shown in FIG. 2 is used in a batch system, the melt of the aromatic polycarbonate prepolymer is completely supplied from the raw material supply port 1 to carry out the polymerization, and after the predetermined degree of polymerization is reached, the discharge port 9 is used. More extracted. In the case of continuous use, the melt of the aromatic polycarbonate prepolymer is continuously supplied from the raw material supply port 1 and the predetermined molecular weight is reached while controlling the amount of the polymer melt in the polymerization vessel to be constant. The obtained polymer is continuously withdrawn from the outlet 9.

The polymerization vessel used in the method of the present invention may be equipped with a stirrer or the like at the bottom of the polymerization vessel, but it is not particularly required. Therefore, it is possible to eliminate the rotation drive part in the main body of the polymerization vessel, and it is possible to carry out the polymerization under a well-sealed condition even under a high vacuum. The sealing performance of the rotary drive unit of the circulation pump provided in the circulation line is better than that in the case where the main body of the polymerizer has the rotary drive unit because of the liquid head.

The method of the present invention can be carried out with one polymerization vessel, but it may be carried out with two or more polymerization vessels. Also, 1
It is also possible to divide the polymerized group of the group into a vertical type or a horizontal type to form a multistage polymerization vessel. In the present invention, the step of increasing the molecular weight from the melt of the aromatic polycarbonate prepolymer to the aromatic polycarbonate can be performed by a method of polymerizing while dropping all along the guide from the porous plate, It is also possible to carry out it in combination with the above polymerization method.

Next, the preferred combination modes of the polymerization method in the present invention are shown below. For example, a method of polymerizing while dropping along a guide, a method of polymerizing using a thin film type polymerization device, a screw type polymerization device, a horizontal stirring polymerization device, etc. It is also possible to produce group polycarbonates. Pre-polymerization step: Stirring tank type polymerization device / Post-polymerization step: Method of polymerizing while dropping from a perforated plate along a guide As a specific example of a preferable combination of polymerization methods in the present invention, a stirring tank-type polymerization in the pre-polymerization step There is a combination of a method of using a vessel and a method of polymerizing while dropping from the porous plate along the guide in the post-polymerization step. Stirring tank type polymerizers generally have high volume efficiency and high stirring efficiency for low-viscosity substances, but the liquid surface area per liquid volume is small, and stirring efficiency for high-viscosity substances is not necessarily high. Therefore, when the production of the aromatic polycarbonate is carried out only in the stirred tank type polymerization vessel, it is difficult to efficiently withdraw the aromatic monohydroxy compound or the like from the polymer having the increased viscosity in the latter half of the polymerization to proceed the polymerization. . Further, since the gas phase portion has a rotation driving portion, polymerization under high vacuum causes a problem of product quality deterioration due to oxygen leakage. However,
Efficient production of high-quality aromatic polycarbonate by combining the method of using a stirred tank polymerization device in the pre-polymerization step with the method of polymerizing while dropping from the porous plate along the guide in the post-polymerization step. You can That is, since the pre-polymerization step does not usually need to be carried out in a high vacuum, the stirring tank type polymerizer does not impair the quality, and since the viscosity is low, the polymerization can be performed with high stirring efficiency and high volume efficiency. In the polymerization process, the method of polymerizing while dropping from the perforated plate along the guide allows the aromatic monohydroxy compound and residual solvent to be efficiently extracted to proceed with the polymerization, resulting in high sealing performance under high vacuum. Since it is also excellent, a high-quality aromatic polycarbonate can be easily produced.

In this example, the prepolymerization step means a step of producing a polymerization intermediate having a number average molecular weight of usually 300 to 5000 from an aromatic polycarbonate prepolymer, and the postpolymerization step means a prepolymerization step. It means a step of producing an aromatic polycarbonate having a higher degree of polymerization than the polymerization intermediate obtained in the polymerization step. The stirring tank type polymerizer may be any of the stirring tanks described in, for example, Chapter 11 of the Chemical Equipment Handbook (edited by the Chemical Engineering Society; 1989). The shape of the tank is not particularly limited, and a vertical type or a horizontal type is usually used. Also, the shape of the stirring blade is not particularly limited,
An anchor type, a turbine type, a screw type, a ribbon type, a double blade type and the like are used.

The reaction temperature and reaction time in the prepolymerization step are usually selected in the range of 50 to 350 ° C., preferably 100 to 290 ° C., usually 1 minute to 100 hours, preferably 30 minutes to 50 hours. The reaction pressure in the prepolymerization step varies depending on the molecular weight of the prepolymer melt,
Usually, the range of 3 mmHg to normal pressure is preferable, and the range of 5 mmHg to normal pressure is more preferable. With the progress of the reaction, nitrogen, in order to efficiently remove the aromatic monohydroxy compound and residual solvent that are generated out of the reaction system,
Introduce an inert gas that does not adversely affect the reaction, such as argon, helium, carbon dioxide or lower hydrocarbon gas,
A method of entraining the produced aromatic monohydroxy compound, residual solvent and the like in these gases is also preferably used.

The prepolymerization step can be carried out in either a batch system or a continuous system. Further, in the prepolymerization step, it is possible to use one agitation type polymerization vessel or a combination of two or more types. In the prepolymerization step, the amount of the aromatic monohydroxy compound, the residual solvent and the like that are usually distilled out is large, and therefore it is preferable to provide a heat exchanger, a vaporization chamber or the like as necessary to evaporate this.

The apparatus, the polymerization method, the polymerization conditions, etc. of the post-polymerization step in this example, that is, the method of polymerizing by dropping from the porous plate along the guide, are as described above. Next, a specific example of this method will be described with reference to the drawings. FIG. 3 is an example of a process that accomplishes the method of the present invention. In FIG. 3, three polymerization vessels are used in the pre-polymerization step and two polymerization vessels are used in the post-polymerization step.

In the prepolymerization step, FIG. 3 shows that the aromatic polycarbonate prepolymer is supplied from the raw material supply ports 1, 1'through the stirring tank type first polymerizer (A) 3 and the stirring tank type first polymerizer (B).
3'is introduced. In addition, the stirring tank type first polymerizer (B)
3'is exactly the same as the stirring tank type first polymerizer (A) 3 and can be used by switching when operating in batch. The inside of the polymerization vessel is under an atmosphere of an inert gas such as nitrogen and is usually controlled at around normal pressure, and the aromatic monohydroxy compound and residual solvent to be distilled out are discharged from the vent ports 2 and 2 '. . The polymerization intermediate 4 obtained by reacting under stirring for a predetermined time is discharged from the discharge ports 5 and 5 ′, transferred by the transfer pump 6 and introduced into the stirring tank type second polymerization device 8 from the supply port 7. .

The inside of the polymerization vessel is controlled under reduced pressure, and the aromatic monohydroxy compound and residual solvent that are distilled out are discharged from the vent port 9. The polymerization intermediate 10 obtained by reacting for a predetermined time under stirring is discharged from the discharge port 11 and transferred to the post-polymerization step by the transfer pump 12. In the post-polymerization step, the polymerization intermediate 10 produced in the pre-polymerization step is supplied from the supply port 13 to the circulation line 14, introduced through the perforated plate 15 into the perforated plate type first polymerizer 16, and guided to the guide 17. Fall along. The inside of the polymerization vessel is controlled to a predetermined pressure, and an aromatic monohydroxy compound distilled from the polymerization intermediate, a residual solvent, and the like, and an inert gas such as nitrogen introduced from the gas supply port 18 as necessary. Are discharged from the vent port 19. The polymerization intermediate that has reached the bottom of the polymerization vessel is again supplied from the porous plate 15 to the inside of the polymerization vessel through the circulation line 14 equipped with the circulation pump 20.
The polymerization intermediate 21 having reached a predetermined molecular weight is transferred by the transfer pump 2
2 is discharged from the discharge port 23, is supplied from the supply port 24, is introduced into the inside of the porous second polymerization vessel 27 through the porous plate 26, and is dropped along the guide 28. The inside of the polymerization vessel is controlled to a predetermined pressure, and an aromatic monohydroxy compound distilled from the polymerization intermediate, a residual solvent, and the like, and an inert gas such as nitrogen introduced from the gas supply port 29 as needed. Are discharged from the vent port 30. The molten polymer 32 is discharged from the discharge port 34 by the discharge pump 33. In each of the pre-polymerization step and the post-polymerization step, each polymerization vessel, circulation line, transfer line, discharge line and the like are heated and kept warm by a jacket or a heater. Pre-polymerization step: Stirring tank type polymerizer / Intermediate polymerization step: Method of polymerizing while dropping in a wet wall type / Post-polymerization step: Method of polymerizing while dropping along a guide from a porous plate Combination of polymerization methods in the present invention Another preferred specific example of the method is to use a stirring tank type polymerization device in the pre-polymerization step, to perform polymerization while dropping in a wet wall system in the intermediate polymerization step, and to drop from the porous plate along the guide in the post-polymerization step. This is a combination of methods of polymerizing while being allowed to proceed.

In the intermediate polymerization step of this example, the polymerization intermediate obtained in the pre-polymerization step is polymerized in a molten state while dropping it in a wet wall system. The method of polymerizing while dropping onto a wet wall makes it possible to efficiently supply latent heat of vaporization of aromatic monohydroxy compounds and residual solvents because a large heat transfer area can be taken, and a large vaporization area can also be taken, resulting in aromatics. It is possible to efficiently extract the monohydroxy compound, the residual solvent and the like to proceed the polymerization.

In this example, the prepolymerization step is a step of producing a polymerization intermediate having a number average molecular weight of usually 300 to 5000 from an aromatic polycarbonate prepolymer, and the intermediate polymerization step is a prepolymerization step. It is a step of producing a polymerization intermediate having a higher molecular weight than that of the polymerization intermediate obtained in the step, that is, a polymerization intermediate having a number average molecular weight of up to about 10,000, and the post-polymerization step is an intermediate polymerization step. It is a step of producing an aromatic polycarbonate having a higher molecular weight than the polymerization intermediate.

The stirring tank type polymerization vessel used in the prepolymerization step, the polymerization method in the prepolymerization step, the polymerization conditions and the like are as described above. In the intermediate polymerization step, as an apparatus for performing polymerization while dropping it in a wet wall system, for example, there is a reactor described in Chapter 11 page 461 of Chemical Equipment Handbook (edited by Japan Society for Chemical Engineering; 1989). The polymerization vessel may be of a multi-tube type, or the dropped polymer may be circulated and polymerized while being dropped again in a wet wall type.

The reaction temperature and reaction time in the intermediate polymerization step are
Usually at a temperature in the range of 50 to 350 ° C, preferably 100 to 290 ° C, usually for 1 minute to 100 hours, preferably 30.
It is selected in the range of minutes to 50 hours. The preferred reaction pressure in the intermediate polymerization step also varies depending on the molecular weight of the melt mixture or the polymerization intermediate. When the number average molecular weight is 1000 or less, the range of 50 mmHg to atmospheric pressure is preferable, and the number average molecular weight is in the range of 1000 to 2000. 3 mmHg ~ 80
The range of mmHg is preferable, and when the number average molecular weight is 2000 or more, 10 mmHg or less, particularly 5 mmHg or less is preferable. As the reaction progresses, it effectively removes the aromatic monohydroxy compounds and residual solvent that are generated out of the reaction system, so that it adversely affects the reaction such as nitrogen, argon, helium, carbon dioxide, and lower hydrocarbon gas. A method of introducing an inert gas which does not reach and entraining the produced aromatic monohydroxy compound or residual solvent in these gases is also preferably used.

The intermediate polymerization step can be carried out in either a batch system or a continuous system. Further, in the intermediate polymerization step, one polymerization vessel or a combination of two or more polymerization vessels can be used. In the intermediate polymerization step, the amount of the aromatic monohydroxy compound and the residual solvent that are usually distilled out is large, and in order to evaporate them, it is preferable to provide a heat exchanger, a vaporization chamber or the like, if necessary.

The apparatus, the polymerization method, the polymerization conditions and the like of the post-polymerization step in this example, that is, the method of dropping from the perforated plate along the guide to perform polymerization are as described above. Next, a specific example of this method will be described with reference to the drawings. FIG. 6 is an example of a process that accomplishes the method of the present invention. In FIG. 6, 3 units in the pre-polymerization process, 1 unit in the intermediate polymerization process,
Two polymerization vessels are used in the post-polymerization step, but this is only a specific example and the present invention is not limited to this.

In FIG. 6, in the prepolymerization step, the aromatic polycarbonate prepolymer is supplied from the raw material supply ports 1 and 1'through the stirring tank type first polymerizer (A) 3 and the stirring tank type first polymerizer (B).
3'is introduced. In addition, the stirring tank type first polymerizer (B)
3'is exactly the same as the stirring tank first polymerizer (A) 3,
It can be used by switching when operating in batch. The inside of the polymerization vessel is under an atmosphere of inert gas such as nitrogen, and is usually controlled near normal pressure.
Distilled aromatic monohydroxy compounds and residual solvent are discharged from the vent ports 2 and 2 '. The polymerization intermediate 4 obtained by reacting under stirring for a predetermined time is discharged from the discharge ports 5 and 5 ′, transferred by the transfer pump 6 and introduced into the stirring tank type second polymerization device 8 from the supply port 7. . The inside of the polymerization vessel is controlled under reduced pressure, and the aromatic monohydroxy compound and residual solvent that are distilled out are discharged from the vent port 9. The polymerization intermediate 10 obtained by reacting for a predetermined time under stirring is discharged from the discharge port 11 and transferred to the intermediate polymerization step by the transfer pump 12.

In the intermediate polymerization step, the polymerization intermediate 10 produced in the pre-polymerization step is supplied to the circulation line 14 through the supply port 13 and introduced into the wet wall type polymerization vessel 16 through the overflow port to form a thin film polymerization intermediate. Become body 17. The inside of the polymerization vessel is controlled to a predetermined pressure, and an aromatic monohydroxy compound distilled from the polymerization intermediate, a residual solvent, and the like, and an inert gas such as nitrogen introduced from the gas supply port 18 as necessary. Are discharged from the vent port 19.
The polymerization intermediate, which has reached the bottom of the polymerization vessel in the form of a thin film, is again overflowed and supplied into the polymerization vessel through a circulation line 14 equipped with a circulation pump 20. The polymerization intermediate 21 having reached a predetermined molecular weight is discharged by the discharge pump 22 to the discharge port 23.
Emitted from.

In the post-polymerization step, the polymerization intermediate 21 produced in the intermediate polymerization step is supplied from the supply port 24 to the circulation line 25 and introduced into the inside of the perforated plate type first polymerization vessel 27 through the perforated plate 26. It falls along the guide 28. The inside of the polymerization vessel is controlled to a predetermined pressure, and an aromatic monohydroxy compound distilled from the polymerization intermediate, a residual solvent, and the like, and an inert gas such as nitrogen introduced from the gas supply port 29 as needed. Are discharged from the vent port 30.
The polymerization intermediate that has reached the bottom of the polymerization vessel is supplied again from the porous plate 26 to the inside of the polymerization vessel through the circulation line 25 equipped with the circulation pump 31. The polymerization intermediate 32 having reached a predetermined molecular weight is discharged from the discharge port 34 by the transfer pump 33, supplied from the supply port 35, introduced into the inside of the porous second polymerization vessel 38 through the porous plate 37, and guided. Fall along 39. The inside of the polymerization vessel is controlled to a predetermined pressure, and the aromatic monohydroxy compound and residual solvent distilled from the polymerization intermediate, and an inert gas such as nitrogen introduced from the gas supply port 40 as necessary. Are discharged from the vent 41. The molten polymer 43 is discharged from the discharge pump 4
4 is discharged from the discharge port 45. In addition, in each of the pre-polymerization step, the intermediate polymerization step, and the post-polymerization step, each of the polymerization units, the circulation line, the transfer line, the discharge line and the like are heated by a jacket or a heater and kept warm.

There are no particular restrictions on the material of the polymerization vessel for achieving the method of the present invention, and it is usually selected from stainless steel, nickel, glass lining and the like. It is also one of the preferred embodiments of the present invention to form a wetting wall on the inner wall surface of the polymerization vessel with a part of the circulating polymer in order to prevent the scale from adhering to the inner surface of the polymerization vessel.

[0076]

BEST MODE FOR CARRYING OUT THE INVENTION Examples will be described below.
It The molecular weight is determined by gel permeation chromatography.
Number average molecular weight (hereinafter referred to as M
Abbreviated as n. ). Percentage of end groups in prepolymer
Is analyzed by high performance liquid chromatography or NM
It was determined by analysis by R. Color is based on CIELAB method
The thickness of the test piece is 3.2 mm, and the yellowness is measured as b. ^*Shown by value
did. The amount of chlorine contained in the aromatic polycarbonate is
It was performed by potentiometric titration method and atomic absorption method.

[0077]

Example 1 64.8 kg of sodium hydroxide was added to 800 parts of water.
Aqueous solution dissolved in kg, Bisphenol A 137 kg,
400 liters of methylene chloride and 1.7k of phenol
g was mixed to make an emulsion, and 58.5 kg of phosgene was gradually blown into this while stirring at 10 to 20 ° C. for 1 hour to react. Then, 0.12 kg of triethylamine was added to this reaction solution, and the mixture was stirred for 1 hour. A sodium hydroxide solution was added to a methylene chloride solution of the prepolymer obtained by liquid separation, and the remaining chloroformate group was decomposed and converted into a phenolate group. Then, it was neutralized with phosphoric acid and washed thoroughly with water. Then, the methylene chloride in the methylene chloride solution of the prepolymer was distilled off, and the residue was dried in a vacuum dryer overnight to give a number average molecular weight of 2400 and a molar ratio of terminal hydroxyl groups to terminal phenyl carbonate groups of 4
A 5/65 aromatic polycarbonate prepolymer was obtained.

Next, the reaction was carried out using a polymerization vessel as shown in FIG. This polymerization vessel has 50 holes with a diameter of 7.5 mm.
Equipped with a perforated plate, each hole has a 1 mm diameter SU
A wire-shaped guide made of S316L is installed penetrating near the center. The height to drop along the guide is 4
m. While supplying the obtained aromatic carbonate prepolymer to this polymerization vessel at 5 liters / hr, the reaction was carried out under the conditions of a reaction temperature of 250 ° C., a reaction pressure of 0.9 mmHg, and a nitrogen gas flow rate of 2 liters / hr. as a result,
Mn3800 colorless and transparent aromatic polycarbonate (b
^* Value 3.1) was obtained. In addition, chlorine analysis of this aromatic polycarbonate was conducted, but no chlorine compound could be detected.

[0079]

Example 2 The reaction was carried out using a polymerization vessel as shown in FIG. This polymerization vessel is equipped with a perforated plate having 50 holes with a hole diameter of 7.5 mm, and each hole has a 1 mm diameter of SUS31.
It is installed so as to penetrate through the vicinity of the central portion of the 6L wire-shaped guide. The height of dropping along the guide is 4 m. Into this polymerization vessel, 15 ttle of the same aromatic polycarbonate prepolymer as that produced in Example 1 was charged,
A batch reaction was carried out for 3 hours under the conditions of a reaction temperature of 248 ° C., a reaction pressure of 1.0 mmHg, a circulation flow rate of 30 liters / hr, and a nitrogen gas flow rate of 1 liter / hr. As a result, Mn77
00 colorless transparent aromatic polycarbonate (b ^* value
3.3) was obtained. In addition, chlorine analysis was conducted, but no chlorine compound was detected. Further, no significant coloring was observed even after injection molding the aromatic polycarbonate at 310 ° C.

[0080]

[Embodiment 3] Using the same apparatus as in Embodiment 2, Embodiment 1
15 liters of the same aromatic polycarbonate prepolymer as that prepared in the above was charged in advance, and the same aromatic polycarbonate prepolymer as the charged one was supplied at 5 liters / hr, while keeping the liquid level constant,
The polymerization reaction was continuously carried out for 500 hours under the conditions of a reaction temperature of 260 ° C., a reaction pressure of 0.5 mmHg, a circulation flow rate of 25 liters / hr, and a nitrogen gas flow rate of 2 liters / hr. The results are summarized in Table 1. After the polymerization was completed, no low-polymerization product or the like was attached to the porous plate. In addition, chlorine analysis was conducted, but no chlorine compound was detected. Further, no significant coloring was observed even after injection molding of this aromatic polycarbonate at 310 ° C.

[0081]

Examples 4 to 7 Polymerization was carried out in the same manner as in Example 3 except that the polymerization conditions were variously changed. The results are summarized in Table 1. In each case, no adhesion of low-polymerization products to the porous plate was observed after the completion of polymerization. Chlorine analysis was conducted, but no chlorine compounds were detected. further,
No noticeable coloration was observed even after injection molding of this aromatic polycarbonate at 310 ° C.

[0082]

[Embodiments 8 to 12] An apparatus exactly similar to that of Embodiment 2 is used, except that the heights along which the guides are dropped are changed to 0.2 m, 0.3 m, 1 m, 2 m, and 8 m. The polymerization reaction was continuously carried out for 500 hours under the same conditions as above. Table 2 shows the results. In each case, after the polymerization was completed, no low polymer was attached to the porous plate. Chlorine analysis was conducted, but no chlorine compounds were detected. Further, no significant coloring was observed even after injection molding the aromatic polycarbonate at 310 ° C.

[0083]

[Embodiment 13] The perforated plate has 110 holes each having a hole diameter of 4.4 mm.
The guide connected to each hole has an S of 2 mm in diameter.
Exactly the same as Example 2 except that the wire is made of US316L
Using the same apparatus, polymerization reaction was conducted under the same conditions as in Example 5.
Responded. 100 hours, 200 hours, 300 hours
After 400 hours and after 500 hours, continuously from the polymerization vessel
Aromatic polycarbonate obtained by mechanical extraction
These are also colorless and transparent (b ^*Value 3.4), each Mn
13100, 13100, 13200, 13200,
It was stable at 13100. After the polymerization is completed,
No adhesion of polymer etc. was observed at all. Also chlorine analysis
However, chlorine compounds were not detected. further,
This aromatic polycarbonate was injection molded at 310 ° C.
After that, no remarkable coloring was observed.

[0084]

[Example 14] Example 14 except that the perforated plate has 50 rectangular holes of 4 mm x 10 mm and the guide connected to each hole is a flat plate made of SUS316L having a width of 8 mm and a thickness of 1 mm. Polymerization was carried out under the same conditions as in Example 5, using the same apparatus as in Example 2. 100 hours later, 20
The aromatic polycarbonates obtained by continuously withdrawing from the polymerization vessel after 0 hours, 300 hours, 400 hours and 500 hours were all colorless and transparent (b ^* value).
3.4), Mn is 11300, 11200, 1 respectively
It was stable at 1200, 11300, and 11200. After the polymerization was completed, no low-polymerization product or the like was attached to the porous plate. In addition, chlorine analysis was conducted, but no chlorine compound was detected. Further, no significant coloring was observed even after injection molding the aromatic polycarbonate at 310 ° C.

[0085]

Comparative Example 1 An aromatic polycarbonate was produced in exactly the same manner as in Example 7, except that a horizontal biaxial stirring type polymerization device was used instead of the porous plate type polymerization device. However, the horizontal twin-screw agitator is
Internal volume is 30 liters, L / D = 6, rotating diameter 140
mm biaxial stirring blades, reaction temperature 250
C., reaction pressure 0.2 mmHg, internal volume 10 liters, aromatic polycarbonate prepolymer supply flow rate was 2 liters / hr. As a result of conducting the polymerization reaction continuously for 500 hours under these operating conditions, after 100 hours, 200 hours, 300 hours, 400 hours and 500 hours,
The aromatic polycarbonates obtained by continuous extraction from the polymerization vessel had b ^* values of 3.6, 3.6 and 3.7, respectively.
3.7 and 3.9, and Mn is 6600 and 65, respectively.
It was 00,6600,6400,6500. The rate of increase in molecular weight at this time was about 1/2 of that in Example 7.

[0086]

Comparative Example 2 69.2 kg of sodium hydroxide was added to 800 parts of water.
Aqueous solution dissolved in kg, bisphenol A 159.3k
g, 0.33 kg of hydrosulfite and 400 liters of methylene chloride to form an emulsion,
Phosgene (78.7 kg) was gradually blown in over 1 hour while stirring at -20 ° C to react. Thereafter, 0.24 kg of triethylamine and 2.85 kg of pt-butylphenol were added to this reaction liquid, and the mixture was stirred for 1 hour. A sodium hydroxide solution was added to a methylene chloride solution of the prepolymer obtained by liquid separation, and the remaining chloroformate group was decomposed and converted into a phenolate group. Then, it was neutralized with phosphoric acid and washed thoroughly with water. Next, the methylene chloride in the methylene chloride solution of the polymer was distilled off, and the product was further dried overnight in a vacuum dryer to obtain a number average molecular weight of 11300 (b ^*
Aromatic polycarbonate of 4.2) was obtained. As a result of chlorine analysis of this aromatic polycarbonate, the chlorine content was 35 ppm. With this polymer, 310
When injection molding was performed at ℃, the b ^* value was 4.8.

[0087]

[Table 1]

[0088]

[Table 2]

[0089]

EFFECTS OF THE INVENTION With a device excellent in sealing property under high vacuum and easy to maintain, it is possible to stably produce a high quality aromatic polycarbonate without coloring at a high polymerization rate for a long period of time.

[Brief description of drawings]

FIG. 1 is a schematic view showing an example of a polymerization vessel used in the present invention.

FIG. 2 is a schematic view showing an example of a polymerization vessel used in the present invention.

FIG. 3 is a schematic diagram showing an example of a process for achieving the method of the present invention.

FIG. 4 is a schematic diagram showing an example of a process for achieving the method of the present invention.

FIG. 5 is a schematic diagram showing an example of a process for achieving the method of the present invention.

FIG. 6 is a schematic diagram showing an example of a process for achieving the method of the present invention.

FIG. 7 is a schematic diagram showing an example of a process for achieving the method of the present invention.

FIG. 8 is a schematic diagram showing an example of a process for achieving the method of the present invention.

[Explanation of symbols]

 In FIGS. 1 and 2, 1 raw material supply port 2 circulation line 3 perforated plate 4 guide 5 gas supply port 6 vent port 7 circulation pump 8 discharge pump 9 discharge port 10 polymerizer main body 1 in FIGS. 3, 4 and 5 Raw material supply port 1 ′ Raw material supply port 2 Vent port 2 ′ Vent port 3 Stirring tank 1st polymerization vessel (A) 3 ′ Stirring tank 1st polymerization vessel (B) 4 Polymerization intermediate 5 Discharge port 5 ′ Discharge port 6 Transfer pump 7 Supply Port 8 Stirring Tank Second Polymerizer Main Body 9 Vent Port 10 Polymerization Intermediate 11 Discharge Port 12 Transfer Pump 13 Supply Port 14 Circulation Line 15 Perforated Plate 16 Perforated Plate First Polymerizer 16 ′ Perforated Plate Polymerizer 17 Guide 18 Gas Supply Port 19 Vent Port 20 Circulation Pump 21 Polymerization Intermediate 22 Transfer Pump 23 Discharge Port 24 Supply Port 25 Circulation Line 26 Perforated Plate 27 Perforated Plate Type Second Polymerizer 28 Guide 2 Gas supply port 30 Vent port 31 Circulation pump 32 Molten polymer 33 Discharge pump 34 Discharge port 1 In FIG. 6 and FIG. 7, 1 raw material supply port 1 ′ raw material supply port 2 vent port 2 ′ vent port 3 stirrer tank first polymerizer ( A) 3'stirring tank first polymerizer (B) 4 polymerization intermediate 5 discharge port 5'discharge port 6 transfer pump 7 supply port 8 stirring tank second polymerization device main body 9 vent port 10 polymerization intermediate 11 discharge port 12 transfer Pump 13 Supply port 14 Circulation line 15 Overflow port 16 Wet wall type polymerizer 17 Thin film polymerization intermediate 18 Gas supply port 19 Vent port 20 Circulation pump 21 Polymerization intermediate 22 Transfer pump 23 Discharge port 24 Supply port 25 Circulation line 26 Perforated Plate 27 Perforated Plate First Polymerizer 28 Guide 29 Gas Supply Port 30 Vent Port 31 Circulation Pump 32 Polymerization Intermediate 33 Transfer Pump 34 Discharge port 35 Supply port 36 Circulation line 37 Perforated plate 38 Perforated plate type second polymerizer 39 Guide 40 Gas supply port 41 Vent port 42 Circulation pump 43 Melted polymer 44 Discharge pump 45 Discharge port 1 Raw material supply in FIG. Port 1'Raw material supply port 2 Vent port 2'Vent port 3 Stirring tank 1st polymerization vessel (A) 3'Stirring tank 1st polymerization vessel (B) 4 Polymerization intermediate 5 Discharge port 5'Discharge port 6 Transfer pump 7 Supply Port 8 Circulation line 9 Overflow port 10 Wet wall type polymerizer 11 Thin film polymerization intermediate 12 Gas supply port 13 Vent port 14 Circulation pump 15 Polymerization intermediate 16 Transfer pump 17 Discharge port 18 Supply port 19 Circulation line 20 Perforated plate 21 Perforated plate type first polymerizer 22 Guide 23 Gas supply port 24 Vent port 25 Circulation pump 26 Polymerization intermediate 27 Transfer pump 28 Discharge Mouth 29 supply port 30 circulation line 31 perforated plate 32 perforated plate-type second polymerizer 33 guide 34 gas supply ports 35 vent 36 circulation pump 37 melt polymer 38 discharge pump 39 discharge port

Claims (11)

[Claims] 1. An aromatic polycarbonate prepolymer is produced by reacting an alkaline aqueous solution of an aromatic dihydroxy compound with phosgene, and the obtained aromatic polycarbonate prepolymer is dropped from a perforated plate along a guide in a molten state. A method for producing an aromatic polycarbonate, which comprises polymerizing. 2. An alkaline aqueous solution of an aromatic dihydroxy compound is reacted with phosgene to produce an aromatic polycarbonate prepolymer, and the obtained aromatic polycarbonate prepolymer is dropped from a perforated plate along a guide in a molten state. A method for producing an aromatic polycarbonate, characterized in that the polymer is polymerized while being dropped, and a part or the whole of the dropped polymer is circulated, and the polymer is polymerized while being dropped again along the guide from the porous plate. 3. An aromatic polycarbonate prepolymer is produced by reacting an alkaline aqueous solution of an aromatic dihydroxy compound with phosgene, and the obtained aromatic polycarbonate prepolymer is continuously supplied to the guide from a perforated plate in a molten state. It is characterized in that it is polymerized while being dropped along it, and a part of the dropped polymer is circulated and polymerized while being dropped along the guide again from the perforated plate to continuously withdraw the aromatic polycarbonate. Process for producing aromatic polycarbonate. 4. An aromatic polycarbonate prepolymer is produced by reacting an alkaline aqueous solution of an aromatic dihydroxy compound with phosgene, and the obtained aromatic polycarbonate prepolymer is polymerized in a molten state using a stirring tank type polymerization device. A method for producing an aromatic polycarbonate comprising a prepolymerization step and a postpolymerization step in which a polymerization intermediate obtained in the prepolymerization step is polymerized in a molten state while being dropped along a guide from a perforated plate. 5. In the post-polymerization step, the polymerization intermediate obtained in the pre-polymerization step is polymerized in a molten state while being dropped along the guide from the porous plate, and a part or all of the dropped polymer is circulated. The method for producing an aromatic polycarbonate according to claim 4, which is a method of causing the porous plate to polymerize while being dropped again along the guide. 6. The post-polymerization step comprises continuously feeding the polymerization intermediate obtained in the pre-polymerization step, polymerizing the polymer in a molten state while dropping it along the guide from the porous plate, and The method for producing an aromatic polycarbonate according to claim 4, which is a method in which a part of the aromatic polycarbonate is continuously circulated and dropped from the perforated plate again along the guide to polymerize the aromatic polycarbonate. 7. An aromatic polycarbonate prepolymer is produced by reacting an alkaline aqueous solution of an aromatic dihydroxy compound with phosgene, and the obtained aromatic prepolymer prepolymer is polymerized in a molten state by using a stirring tank type polymerization device. Pre-polymerization step to allow, the intermediate polymerization step of polymerizing the polymerization intermediate obtained in the pre-polymerization step while falling in a molten state in a wet wall system, and the polymerization intermediate obtained in the intermediate polymerization step from the porous plate to the guide. A method for producing an aromatic polycarbonate, characterized by including a post-polymerization step of polymerizing while dropping along with it. 8. The post-polymerization step causes the polymerization intermediate obtained in the intermediate polymerization step to be polymerized in a molten state while being dropped along the guide from the perforated plate, and a part or all of the dropped polymer is circulated. 8. The method for producing an aromatic polycarbonate according to claim 7, which is a method of polymerizing while allowing the porous plate to fall along the guide again. 9. The post-polymerization step comprises continuously feeding the polymerization intermediate obtained in the intermediate polymerization step, polymerizing the polymer in a molten state while dropping it along the guide from the porous plate, and The method for producing an aromatic polycarbonate according to claim 7, which is a method in which a part of the aromatic polycarbonate is continuously circulated and dropped from the porous plate again along the guide to polymerize the aromatic polycarbonate. 10. The height of dropping from the perforated plate along the guide is 0.3 m or more, 1, 2, 3,
A method for producing an aromatic polycarbonate according to 4, 5, 6, 7, 8 or 9. 11. The aromatic polycarbonate prepolymer obtained by reacting an alkaline aqueous solution of an aromatic dihydroxy compound with phosgene has a number average molecular weight of 300 to 200.
00 range, Claims 1, 2, 3, 4, 5, 6,
7. The method for producing an aromatic polycarbonate according to 7, 8 or 9.