JP2000072868A - Production of aromatic polycarbonate resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an aromatic polycarbonate resin causing no environmental problem, capable of being produced through a low-priced transesterification process and excellent in hue by installing plural reactors in series and by forming a prepolymer from a raw material such as an aromatic dihydroxy compound or the like in a reactor equipped with a specific rectifier in a previous step to further polymerize it in a reactor in a latter step. SOLUTION: When reacting a reactant mixture of an aromatic dihydroxy compound such as 2,2-bis(4-hydroxyphenyl)propane or the like with a dicarbonate (pref. diphenyl carbonate) pref. in the presence of a catalyst such as an alkali metal compound (or in the absence of a catalyst) in two or more reactors installed in series, the objective resin is obtained by forming a prepolymer from the above reactant mixture in at least one reactor equipped with a rectifier (pref. showing <=15 Torr pressure drop) having a reflux mechanism filled with an ordered packing such as a through-the-packing in a previous step for initial transesterification reaction, followed by feeding it to a reactor in a latter step to further polymerize it.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing an aromatic polycarbonate resin, and more particularly, to a method for producing an aromatic polycarbonate resin.
The present invention relates to a method for producing an aromatic polycarbonate resin having excellent hue.

[0002]

2. Description of the Related Art Polycarbonate is widely used because it has excellent mechanical properties such as impact resistance, and also has excellent heat resistance and transparency. As a method for producing such a polycarbonate, a method of directly reacting an aromatic dihydroxy compound such as bisphenol with phosgene (interfacial method) or a method of melting an aromatic dihydroxy compound such as bisphenol and an aromatic carbonate diester such as diphenyl carbonate is used. Transesterification in the state (melting method)
A method for causing this to occur is known.

Among such production methods, a method for producing a polycarbonate by a transesterification reaction between an aromatic dihydroxy compound and a carbonic acid diester does not use toxic phosgene and does not use methylene chloride as a solvent. It is a manufacturing method that does not have any problems and has attracted attention as a manufacturing method that has the possibility of being inexpensive in terms of cost. However, the method of producing a polycarbonate by transesterification is said to deteriorate the quality of the obtained polycarbonate, particularly the hue, because the polymerization is carried out for a long time under severe conditions compared to the interface method, in other words, at a high temperature and a high degree of vacuum. Had a problem.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for producing a polycarbonate resin having an excellent hue by using a transesterification method which has no environmental problems and is economical.

[0005]

That is, the present invention comprises the following techniques.

[0006] 1. In a method for preparing an aromatic polycarbonate resin, a reaction mixture containing an aromatic dihydroxy compound and a carbonic acid diester is reacted in the presence / absence of a catalyst by installing two or more reaction tanks in series. A rectification column having a reflux mechanism filled with an ordered packing is installed in at least one of the reaction tanks in the former stage used for the polymerization, polymerization is performed, and a prepolymer is generated. And producing the aromatic polycarbonate resin.

[0007] 2. Two or more reaction tanks are installed in series, and a reaction mixture containing an aromatic dihydroxy compound and a carbonic acid diester is reacted in the presence / absence of a catalyst to form an aromatic polycarbonate resin. At the stage where a prepolymer having a viscosity average molecular weight of 1000 or more is polymerized at a reaction tank internal pressure of 100 Torr or less, using one or more reaction vessels having a rectification column having a reflux mechanism filled with an ordered packing, Then, the prepolymer is supplied to a reaction tank at a subsequent stage, and is further polymerized, thereby producing an aromatic polycarbonate resin.

[0008] 3. Two or more reaction tanks are installed in series, and a reaction mixture containing an aromatic dihydroxy compound and a carbonic acid diester is reacted in the presence / absence of a catalyst to form an aromatic polycarbonate resin. In the step of polymerizing at a reaction tank internal pressure of 20 Torr or less to obtain a prepolymer having a viscosity average molecular weight of 4000 or more, one or more reaction tanks having a rectification column filled with an ordered packing are used. A method for producing an aromatic polycarbonate resin, comprising supplying a polymer to a subsequent reaction tank and further polymerizing the polymer.

4. 4. The method according to any one of the above-mentioned items 1, 2, and 3, wherein the pressure loss of the rectification column filled with the ordered packing is 15 Torr or less.

[0010] 5. The method according to any one of claims 1, 2, 3, and 4, wherein the first reactor having a rectification tower is a vertical stirring vessel, and the second reactor having no rectification tower is a horizontal stirring vessel. .

6. The above-mentioned 1, 2, 3, 4, 5 wherein the carbonic acid diester is diphenyl carbonate
The manufacturing method as described.

7. 7. The method according to any one of the above items 1, 2, 3, 4, 5, and 6, wherein the catalyst is an alkali metal compound or an alkaline earth metal compound and a nitrogen-containing basic compound.

In the present invention, the aromatic polycarbonate is a reaction mixture containing an aromatic dihydroxy compound, which is a main component, and a carbonate ester, and a basic nitrogen compound, an alkali metal compound and / or an alkaline earth metal compound. Is an aromatic polycarbonate melt-polycondensed in the presence of a transesterification catalyst or the like. Here, in the specification of the present application, the term "reaction mixture" refers to a mixture mainly containing an aromatic dihydroxy compound and an aromatic carbonic acid diester, which is obtained by mixing a nitrogen-containing basic compound with an alkali metal compound and / or an alkaline earth metal compound. In the presence or absence of a transesterification catalyst or the like, in the process of performing a melt polycondensation reaction to obtain an aromatic polycarbonate, means a mixture that has begun or is undergoing the polycondensation reaction, and has a degree of polymerization of Are advanced to some extent in general chemical terms, "prepolymers," and further advanced are in general chemical terms, "polymers." In the present specification, the reaction mixture at the outlet of each reaction vessel or group of reaction vessels is referred to as a prepolymer.

Specific examples of such aromatic dihydroxy compounds include bis (4-hydroxyphenyl) methane, 2,2-bis (4-hydroxyphenyl) propane, and 2,2-bis (4-hydroxy-3). -Methylphenyl) propane, 4,4-bis (4-hydroxyphenyl) heptane, 2,2-bis (4-hydroxy-3,5
-Dichlorophenyl) propane, 2,2-bis (4-hydroxy-3,5-dibromophenyl) propane, bis (4-hydroxyphenyl) oxide, bis (3,5
-Dichloro-4-hydroxyphenyl) oxide,
p, p'-dihydroxydiphenyl, 3,3'-dichloro-4,4'-dihydroxydiphenyl, bis (hydroxyphenyl) sulfone, resorcinol, hydroquinone, 1,4-dihydroxy-2,5-dichlorobenzene, 1,4 -Dihydroxy-3-methylbenzene, bis (4-hydroxyphenyl) sulfide, bis (4-hydroxyphenyl) sulfoxide and the like are listed, and 2,2-bis (4-hydroxyphenyl) propane is particularly preferred.

As the carbonic acid diester, specifically, diphenyl carbonate, ditolyl carbonate, bis (chlorophenyl) carbonate, m-cresyl carbonate, dinaphthyl carbonate, bis (diphenyl)
Carbonate, dimethyl carbonate, diethyl carbonate, dibutyl carbonate, dicyclohexyl carbonate and the like are used, and diphenyl carbonate is particularly preferable.

Further, if necessary, the polycarbonate of the present invention may contain aliphatic diols such as ethylene glycol, 1,4-butanediol, 1,4-cyclohexanedimethanol, and 1,10-decanediol. Examples of the dicarboxylic acids include succinic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, adipic acid, cyclohexanecarboxylic acid, and tereflutaic acid; oxyacids such as lactic acid, P-hydroxybenzoic acid, and 6-hydroxy-2-naphthoic acid It may contain an acid or the like.

The alkali metal compound used as a catalyst includes, for example, hydroxides, bicarbonates, carbonates, acetates, nitrates, nitrites, sulfites, cyanates, thiocyanates, stearates of alkali metals. Borohydride, benzoate, hydrogen phosphate, bisphenol, phenol salt and the like.

Specific examples include sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium hydrogen carbonate, potassium hydrogen carbonate, lithium hydrogen carbonate, sodium carbonate,
Potassium carbonate, lithium carbonate, sodium acetate, potassium acetate, lithium acetate, sodium nitrate, potassium nitrate, lithium nitrate, sodium nitrite, potassium nitrite, lithium nitrite, sodium sulfite, potassium sulfite, lithium sulfite, sodium cyanate, potassium cyanate , Lithium cyanate, sodium thiocyanate,
Potassium thiocyanate, lithium thiocyanate, sodium stearate, potassium stearate, lithium stearate, sodium borohydride, potassium borohydride, lithium borohydride, sodium phenylated borate, sodium benzoate, potassium benzoate, benzoate Examples thereof include lithium acid, disodium hydrogen phosphate, dipotassium hydrogen phosphate, dilithium hydrogen phosphate, disodium salt, dipotassium salt, dilithium salt of bisphenol A, sodium salt, potassium salt, and lithium salt of phenol.

The alkali metal compound as a catalyst is used as a metal in an amount of 1 × 10 ⁻⁸ to 1 mol per mole of the aromatic diol compound.
It is preferably used at a ratio of 5 × 10 ⁻⁵ equivalent. A more preferable ratio is 5 × 10 ⁻⁷ to 1 × 10 ^{−5 with} respect to the same standard.
This is the equivalent ratio. If the amount is outside the above range, the properties of the obtained polycarbonate are adversely affected, and the transesterification reaction does not sufficiently proceed to obtain a high-molecular-weight polycarbonate, which is not preferable.

Examples of the nitrogen-containing basic compound as a catalyst include, for example, tetramethylammonium hydroxide (Me ₄ NOH), tetraethylammonium hydroxide (Et ₄ NOH), tetrabutylammonium hydroxide (Bu ₄ NOH), benzyl Ammonium hydroxides having alkyl, aryl, alkylaryl groups such as trimethylammonium hydroxide (φ-CH ₂ (Me) ₃ NOH), hexadecyltrimethylammonium hydroxide, triethylamine, tributylamine, dimethylbenzylamine, hexadecyl Tertiary amines such as dimethylamine, or tetramethylammonium borohydride (Me ₄ NB
H ₄ ), basic salts such as tetrabutylammonium borohydride (Bu ₄ NBH ₄ ), tetrabutylammonium tetraphenylborate (Me ₄ NBPh ₄ ), and tetrabutylammonium tetraphenylborate (Bu ₄ NBPh ₄ ). it can.

The above-mentioned nitrogen-containing basic compound is 1 × 10 ^-5 as a basic nitrogen element per mole of the aromatic diol compound.
It is preferably used at a ratio of up to 5 × 10 ⁻⁴ equivalent. A more desirable ratio is 2 × 10 ^{−5 to} 5 × 10 with respect to the same standard.
^-4 equivalents. A particularly desirable ratio is a ratio that is 5 × 10 ^{−5 to} 5 × 10 ⁻⁴ equivalents with respect to the same standard.

In the present invention, if desired, the alkali metal compound of the catalyst may be (a) an alkali metal salt of an ate complex of an element of Group 14 of the periodic table or (b) an oxo acid of an element of Group 14 of the periodic table. Can be used. Here, the elements of Group 14 of the periodic table refer to silicon, germanium, and tin.

The use of these alkali metal compounds as a polycondensation reaction catalyst has the advantage that the polycondensation reaction can be promptly and sufficiently promoted. Further, undesirable side reactions such as a branching reaction generated during the polycondensation reaction can be suppressed to a low level.

(A) As an alkali metal salt of an ate complex of a group 14 element of the periodic table, those described in JP-A-7-268091 are mentioned, and specifically, a compound of germanium (Ge); NaGe (OMe) ₅ , NaGe
(OEt) ₃ , NaGe (OPr) ₅ , NaGe (OB
u) ₅ , NaGe (OPh) ₅ , LiGe (OMe) ₅ ,
LiGe (OBu) ₅ and LiGe (OPh) ₅ can be given.

As a compound of tin (Sn), NaSn
(OMe) ₃ , NaSn (OMe) ₂ (OEt), NaS
n (OPr) ₃ , NaSn (On-C ₆ H ₁₃ ) ₃ , Na
Sn (OMe) ₅ , NaSn (OEt) ₅ , NaSn (O
_{Bu) 5, NaSn (O-} n-C 12 H 25) 5, NaSn
(OEt), NaSn (OPh) ₅ , NaSnBu ₂ (O
Me) ₃ can be mentioned.

(B) The alkali metal salt of an oxo acid of Group 14 element of the periodic table includes, for example, silicic acid (silicic acid).
Cic acid), stannic acid (sta)
alkali metal salt of germanic acid, germanium (II) acid, germanic acid (germanic acid), germanic acid (germanic acid)
The alkali metal salts of acid) can be mentioned as preferred.

The alkali metal salt of silicic acid is, for example, an acidic or neutral alkali metal salt of monosilicic acid (monosilicic acid) or a condensate thereof, and examples thereof include monosodium orthosilicate, disodium orthosilicate, and orthosilicate. Trisodium and tetrasodium orthosilicate can be mentioned.

The alkali metal salt of stannic acid is, for example, an acidic or neutral alkali metal salt of monostannic acid or a condensate thereof, and examples thereof include disodium monostannate (Na ₂ SnO ₃ .C).
_{H 2 O, x = 0~5)} , mention may be made of Monosuzu acid tetrasodium salt (Na ₄ SnO _4).

Germano (II) acid (germano)
Us acid) alkali metal salts are, for example, acidic or neutral alkali metal salts of monogermanic acid or a condensate thereof, and examples thereof include monosodium germanate (NaHGeO ₂ ).

Germanium (IV) acid (germani)
The alkali metal salt of c acid) is, for example, an acidic or neutral alkali metal salt of monogermanic (IV) acid or a condensate thereof, and examples thereof include monogermanic acid ortholithate (LiH ₃ GeO ₄ ) orthogermanate. Disodium salt, tetrasodium orthogermanate, disodium digermanate (N
a ₂ Ge ₂ O _5), tetra-germanium disodium salt _{(Na 2 Ge 4 O 9)} , penta germanium disodium salt (Na ₂ Ge ₅ O ₁₁₎ can be exemplified.

In the above polycondensation reaction catalyst, the alkali metal element in the catalyst comprising an alkali metal compound and / or an alkaline earth metal compound contains an aromatic diol compound 1
It is preferably used in a ratio of 1 × 10 ^{−8 to} 5 × 10 ⁻⁵ equivalent per mole. A more desirable ratio is 5 for the same standard.
It is the ratio that becomes ^10-7 to ^1-10-5 equivalents.

In the polycondensation reaction of the present invention, at least one member selected from the group consisting of an oxo acid of Group 14 element of the periodic table and an oxide of the same element, if necessary, together with the above catalyst.
Various co-catalysts can be co-present.

By using these cocatalysts at a specific ratio, the terminal blocking reaction and the polycondensation reaction rate are not impaired, the branching reaction which is easily generated during the polycondensation reaction, or the foreign matter in the apparatus during the molding process is performed. Undesirable side reactions such as generation and burning can be more effectively suppressed.

The oxo acids of Group 14 elements of the periodic table include, for example, silicic acid, stannic acid and germanic acid.

The oxides of the Group 14 elements of the periodic table include:
Mention may be made of silicon monoxide, silicon dioxide, tin monoxide, tin dioxide, germanium monoxide, germanium dioxide and condensates thereof.

The cocatalyst should be present in a proportion such that the metal element of Group 14 of the periodic table in the cocatalyst is not more than 50 mol (atoms) per 1 mol (atom) of the alkali metal element in the polycondensation reaction catalyst. preferable. If the co-catalyst is used in a proportion of more than 50 moles (atoms) of the same metal element, the rate of polycondensation reaction is undesirably reduced.

The cocatalyst is present in such a proportion that the metal element of Group 14 of the periodic table of the cocatalyst is 0.1 to 30 mol (atoms) per 1 mol (atom) of the alkali metal element of the polycondensation reaction catalyst. Is more preferred.

These catalyst systems have the advantage that the polycondensation reaction and the end-capping reaction can be promptly and sufficiently proceeded by being used in the polycondensation reaction. Further, undesirable side reactions such as a branching reaction generated in the polycondensation reaction system can be suppressed to a low level.

In the present invention, there is no particular limitation on the equipment and process used for producing a polycarbonate by transesterifying an aromatic dihydroxy compound and a carbonic acid diester, and conventionally known equipment and processes can be used. The following can be mentioned.

When the transesterification reaction is carried out by a batch operation, the viscosity of the reaction system changes greatly with the progress of the transesterification reaction, and the amount of monohydroxy compound produced as a by-product in the reaction changes greatly. It is common practice to use two reactors for the following reasons.

In this case, the first reaction tank is provided with a rectification column for separating the unreacted carbonic acid diester from the by-produced monohydroxy compound and refluxing the unreacted carbonic acid diester in the reaction system. Type stirring tanks are widely used.

In this process, a large amount of a monohydroxy compound is generated, which must be removed by evaporation.
It is often practiced to cover the entire reaction tank with a jacket and to install a heat transfer coil in the reaction tank or to install a heat exchanger outside to increase the heating capacity.

As the stirring blade, a high-efficiency paddle blade having excellent performance from low to medium viscosity such as a full zone blade (Shinko) or a max blend blade (Sumitomo Heavy Industries) is preferably used.

Further, the material of the reaction tank must have corrosion resistance to the monohydroxy compound produced as a by-product, and a material having a low iron content such as nickel or stainless steel is preferably used in a portion in contact with the reaction solution. .

The reaction solution in which the transesterification reaction has been carried out in the first reaction tank and the starting monomers have been sufficiently reacted is transferred to the second reaction tank, and the transesterification reaction is continued to a predetermined degree of polymerization.

As the second reaction tank used for this purpose, a vertical or horizontal stirring tank is used, but a horizontal reaction tank capable of keeping the liquid depth low is preferable. In addition, a rectification column is generally not provided because the reaction pressure is often a high degree of vacuum and there is no unreacted carbonic diester enough to affect the molar balance of the raw materials. In many cases, helical ribbon blades or anchor blades which exhibit high viscosity and excellent performance are also used as the stirring blades.

Although the material constituting the second reaction vessel is not so strictly required as that of the first reaction vessel, a material containing much iron should also be avoided, and is preferably constituted by stainless steel or the like.

When the polymerization is carried out batchwise, the aromatic dihydroxy compound and the carbonic acid diester as the raw materials are weighed so as to have a predetermined molar ratio, and then charged into the first reaction tank.

The molar ratio of the carbonic acid diester to the aromatic dihydroxy compound varies depending on the capacity of the rectification column, the conversion of the monomer in the first reaction tank, and the amount of OH end groups of the polycarbonate to be obtained. 8-1.
5 preferably 0.95 to 1.1, more preferably 1.0 to 1.0
1.05 is used.

In the present invention, the presence of oxygen should be avoided. After the raw materials have been charged into the reaction tank, the charging port is sealed, and if there is a possibility that air is mixed into the reaction tank due to the charging of the raw materials, nitrogen or the like is used. The inside of the reaction tank is sufficiently replaced with the inert gas. Thereafter, the temperature is increased and the raw materials are uniformly dissolved with stirring. The melting temperature varies depending on the melting point of the raw material, but usually 100 to 180 ° C is used.

When a catalyst is used in the transesterification reaction, it is common practice to charge a predetermined amount of the catalyst at the same time as the raw materials are charged, or to charge them after the raw materials are dissolved. In the latter case, it is preferable to use a dedicated charging device to prevent air from being mixed.

When the raw materials are uniformly dissolved, the temperature is increased while stirring in the presence / absence of a catalyst, and the resulting monohydroxy compound is removed from the system to carry out a transesterification reaction.

The temperature at this time is 180 to 250 ° C., preferably 200 to 250 ° C.

The pressure of the reaction system is reduced to promote the removal of the produced monohydroxy compound.
Preferably, 100 to 10 Torr is used.

Since the monohydroxy compound thus removed out of the system is accompanied by a considerable amount of carbonic acid diester, the resulting vapor is led to a rectification column and brought into sufficient contact with the condensate to form the carbonic acid diester. Is separated and returned to the reaction system. Thus, in the first reaction tank, the viscosity average molecular weight is 1,000 to 10,000, preferably 4 to 10,000.
The transesterification reaction is carried out until it becomes 000-8000.

The end point of the reaction in the first reaction tank is determined by various methods. For example, the amount of the distilling monohydroxy compound and the reaction time are used.

The reaction solution thus produced is then transferred to a second reaction tank. Usually, pressure transfer using a pressure difference or a head difference, and transfer using a pump are used for the transfer.

The reaction liquid transferred to the second reaction tank is added with a catalyst as needed, and then the reaction is continued to a predetermined degree of polymerization while further increasing the temperature and the degree of vacuum while stirring. In this case, the reaction temperature is usually 250 to 300 ° C, and the reaction pressure is 10 to
0.1 Torr is commonly used. Further, the degree of polymerization is often controlled by the power of stirring or the like.

Adjustment of the degree of vacuum in both the first reaction tank and the second reaction tank is performed by adjusting the opening of a pressure control valve or a leak valve installed in a vacuum line, and in the latter case, it is improper. It is desirable to use an active gas as a leak gas.

The temperature of the first reaction tank and the second reaction tank is generally adjusted by the temperature of the heat medium flowing through a jacket or the like. It is generally preferable that the temperature is 50 ° C. or less in the first reaction tank where the amount of monohydroxy compound generated is large, and 3 ° C.
Temperature differences of 0 ° C. or less are used.

When the present invention is carried out in a continuous system, devices having the functions of raw material preparation, raw material supply, initial polymerization, late polymerization, etc. are arranged in series, and the catalyst is supplied to the polymerization tank as a separate system as required. Equipment that can be used is used.

In the continuous operation, the dissolution and preparation of the raw materials may be performed intermittently or continuously.

In the case of intermittent operation, after a fixed amount of carbonate diester in a molten state is charged into the raw material preparation tank, the molar ratio of carbonate diester to aromatic dihydroxy compound is usually 0.8 to 1.5, preferably The aromatic dihydroxy compound is gradually charged while stirring so as to be 0.95 to 1.1, more preferably 1.0 to 1.05, uniformly melted, and then maintained at a constant temperature and transferred to the raw material supply tank. I do. In this case, the temperature depends on the melting point of the raw material,
0-180 ° C is used.

In the case where the raw material is continuously dissolved and prepared, the molten carbonate diester and the molten aromatic dihydroxy compound are continuously supplied at a constant ratio to a preparation tank equipped with a stirrer. You. In this case, the raw material preparation tank and the raw material supply tank can also serve as, and further, in a pipe equipped with a line mixer, when mixing the molten carbonate diester and the molten aromatic dihydroxy compound,
Both the raw material preparation tank and the raw material supply tank can be omitted. In these cases, the temperature must be maintained at or above the melting point of each raw material and mixture, and is usually 100 to 18
0 ° C. is used.

There is no particular limitation on the material of the equipment used for dissolving and preparing these raw materials, but materials containing a large amount of iron should be avoided, and stainless steel is usually used.

Regardless of whether the process is intermittent or continuous, the presence of air, especially oxygen, should be avoided in the operation of dissolving and preparing the raw material, and the apparatus used for dissolving and preparing should be sufficiently replaced with an inert gas such as nitrogen. It is preferable to perform purging with an inert gas.

The raw material thus prepared is supplied to a preceding reaction tank at a controlled flow rate through a metering pump, if necessary. When using a metering pump, generally the viscosity of the molten raw material and the mixture thereof is low, for example, a plunger pump, a discharge pressure such as a diaphragm pump is taken, a pump of a type suitable for a low-viscosity liquid is preferably used, It is preferable to install a back pressure valve on the discharge side.

Filtration can be performed for the purpose of removing minute foreign substances present in the raw material in the process of supplying the prepared raw material to the reaction tank in the preceding stage. As the filter used for this purpose, a known filter such as a candle type, a pleated type or a disk type is preferably used, and the filter having an opening of 10 μ or less, preferably 5 μ or less is used.

When a transesterification catalyst is used, a group of equipment having a system similar to the raw material preparation tank is used, and a separate line from the raw material supply line in the initial reaction tank or in the middle thereof at a fixed ratio to the raw material supply amount. Supplied. Transesterification catalysts are often used in the form of a solution or dispersion in a solvent, in which case they affect the reaction of water, monohydroxy compounds such as phenol, aromatic dihydroxy compounds used as raw materials, or carbonic acid diesters. Substances that do not give are preferably used as solvents.

In the present invention, the former reaction tank means the first reaction tank in a batch operation, but does not necessarily mean one apparatus in a continuous operation. Means one or more units for performing the transesterification initial reaction in the production of Here, the transesterification initial reaction refers to the reaction of a monohydroxy compound which has a low viscosity of a polymer produced as a result of the reaction, contains a relatively large amount of unreacted aromatic dihydroxy compound or carbonic acid diester, and as a result, a by-product. It means a region where diffusion resistance in liquid can be neglected in consideration of removal to the outside of the system, and is specifically described later. Actually, the former reaction tank referred to in the present invention is preferably constituted by using one or more vertical stirring tanks according to the production capacity of polycarbonate and the like.

Each of the vertical stirring tanks is provided with an internal coil and an external heat exchanger in order to secure a large heat transfer area.
A rectification column provided with a reflux mechanism for separating a monohydroxy compound generated in the reaction and a carbonic acid diester as a raw material is provided. In this case, the rectification tower provided with one reflux mechanism can be shared between the vertical stirring tanks having the same operation pressure.

When a plurality of reaction tanks are used, it is important to control the residence time of each reaction tank at a constant level. Liquid level management linked with a level meter, liquid level management such as a gear pump in the transfer pipe, and liquid level linked with the level meter of the reaction tank are implemented. Usually, the residence time of each reaction vessel is maintained at 5 hours or less, preferably 2 hours or less, more preferably 1 hour or less.

The material used for the liquid contact part of the former reaction tank is preferably a material containing less iron, such as nickel and stainless steel.

The operating conditions of the first reactor are 180 to 250.
C., preferably at a temperature of 200-250.degree.
Torr pressure is used. It is preferable that the operating temperature and the degree of vacuum are sequentially strengthened as the transesterification proceeds (that is, the temperature is raised to a higher temperature and the degree of vacuum is made higher).

As described above, in the first reaction tank, the viscosity-average molecular weight, which is the initial transesterification reaction, is 1000 to 1
000, preferably from 4000 to 8000, and the reaction rate of the raw material is 95% or more, preferably 99% or more.
%, More preferably 99.5% or more. That is, the “initial transesterification reaction” means that the viscosity average molecular weight of the reaction mixture is 1000 to 1000 in terms of the progress of the reaction.
It means a polymerization reaction until it becomes 10,000, preferably 4,000 to 8,000, and the reaction rate of the raw material is increased to 95% or more, preferably 99% or more, more preferably 99.5% or more.

The reactants generated in the first reactor are quantitatively supplied to the second reactor using a gear pump or the like. In this process, the reactants may be filtered for the purpose of removing foreign substances if necessary. Will be As the filter used for this purpose, a known filter such as a candle type, a pleated type or a disk type is preferably used.
Preferably, those having a size of 10 μm or less are used.

When the present invention is carried out in a continuous operation, the latter-stage reaction tank means a second reaction tank in a batch operation, but when it is carried out in a continuous operation, it necessarily means one apparatus. Rather, it refers to one or more devices that perform a late transesterification reaction. Here, the late transesterification reaction means that the viscosity of the polymer produced as a result of the reaction is high, the terminal OH group or phenyl group involved in the transesterification reaction is relatively small, and as a result, the This is a reaction in a region where diffusion resistance in liquid cannot be ignored in considering removal to the outside of the reaction system, and means a reaction for producing polycarbonate after the above-mentioned “initial transesterification reaction”.

However, this is viewed from the progress of the reaction. In the present invention, the “first stage reaction vessel”, “initial transesterification reaction”, “second stage reaction vessel”, and “late transesterification reaction” Is determined by the presence or absence of a rectification column. That is, after the last one reaction vessel having a rectification tower, the reaction vessel group having no rectification tower is the latter reaction vessel, and the earlier reaction vessel group is the previous reaction vessel. . Therefore, some of the former reactors may not have a rectification column. In the case of batch-type polymerization, the first reaction tank corresponds to the "pre-stage reaction tank", the reaction performed in the first reaction tank corresponds to the "initial transesterification reaction", and the second reaction tank corresponds to the "initial transesterification reaction". The reaction carried out in the “second-stage reaction vessel” in the second reaction vessel corresponds to the “transesterification late-stage reaction”.

Actually, the latter reaction tank referred to in the present invention is preferably composed of one or more horizontal stirring tanks depending on the production capacity of polycarbonate and the like. Since each horizontal stirring tank is operated at a high degree of vacuum, it does not have a rectification column and is directly connected to a vacuum generator via a collector for low molecular weight substances such as monohydroxy compounds generated. It is preferable to use a jacket provided entirely on the jacket for the purpose of preventing heat radiation and removing stirring heat to maintain the operating temperature, and it is also preferable that the jacket be subdivided so that the jacket temperature can be changed. Will be implemented.

As the horizontal stirring tank, a single-shaft reaction tank and a two-shaft reaction tank can be used. Generally, the viscosity of the reaction product is 8,000 poise or less, preferably 6000 poise under operating conditions.
A horizontal single-shaft reaction tank is preferably used at a poise or lower, more preferably 4000 poise or lower, and a horizontal twin-screw reactor is preferably used at a viscosity higher than that. In this case, stirring blades of various shapes are used to increase the surface area of the reaction solution and reduce the staying portion, for example,
Eyeglass wings, lattice wings (Hitachi), SCR, NS
CR, HVR (Mitsubishi Heavy Industries), BIVOLAK (Sumitomo Heavy Industries), RTC (Buss SMS), ORP, CR
P, DISCOTHERM B (LIST) and the like are preferably used. In addition, the viscosity of the reaction product is 5000 pois
In the case of exceeding e, a reaction vessel having a single-screw or twin-screw for withdrawing the reactant is preferably used.

When a plurality of reaction tanks are used, it is important to keep the residence time of each reaction tank constant. For example, a quantitative pump such as a gear pump is provided in a transfer pipe and The liquid level is controlled by linking the amount with the level meter of the reaction tank.
The time is maintained for not more than 5 hours, preferably not more than 5 hours, more preferably not more than 2 hours.

The material used for the liquid contact part of the latter reaction tank is preferably a material containing less iron, such as nickel and stainless steel.

The operating conditions of the latter reaction tank are 250 to 300
° C, preferably 260-290 ° C and 10-0.1
A pressure of Torr, preferably 5 to 0.5 Torr is used. Further, it is preferable that the operating temperature and the degree of vacuum are sequentially strengthened in the subsequent stirring tank. In this way, the polymerization is carried out in the late-stage reactor to a viscosity average molecular weight of 10,000 or more, preferably 15,000 or more, depending on the purpose.

In the late stage of the transesterification, it is necessary to control the progress of polymerization so that a polycarbonate having the desired degree of polymerization is finally obtained. It is preferable to control the degree of polymerization by feeding back to the conditions of the polymerization tank while constantly monitoring the degree of polymerization by installing a viscometer.

The reactant produced in the latter reaction tank is quantitatively extracted using a gear pump or the like, and after adding additives as required, it is commercialized. In this process, foreign substances are removed as necessary. The reaction is also filtered for the purpose. The filters used for this purpose are candle-shaped,
A known filter such as a pleated or disc-shaped filter is preferably used.
40 μm or less for 00 or less, 100 for more than
Those having μ or less are preferably used.

In the present invention, regardless of whether it is a batch type or a continuous type,
The type of the reaction tank used is a vertical stirring tank, a horizontal multi-stage stirring tank,
Various types of reaction tanks, such as a horizontal single-shaft stirring tank and a horizontal twin-shaft stirring tank, can be used in any combination. Among the combinations, the first-stage reaction tank having a rectification tower is vertically stirred. It is a particularly preferable combination to use a tank and a later-stage reaction tank having no rectification column as a horizontal stirring tank even in the case where economic efficiency is considered.

According to the study of the present inventors, in the method for producing an aromatic polycarbonate using the transesterification reaction as described above, the structure of the former reaction tank, more specifically,
It was found that the structure of the rectification column attached to the former reaction tank had a great effect on the hue of the obtained polycarbonate.

Among the reactions at the preceding stage, the structure of the rectification column used in the region where the viscosity average molecular weight is 1,000 to 8,000 is particularly important.

In this region, the viscosity of the reaction system increases due to the specialty of the transesterification reaction of polycarbonate, despite the presence of a sufficient amount of unreacted monomer to affect the molar balance. A phenomenon in which the removal of the monohydroxy compound generated in the exchange reaction to the outside of the system is suppressed starts to occur.

Although this degree is not so large as to require a horizontal reaction tank, it is economically advantageous, but it has been found that it has a great effect on the polymerization rate of a vertical stirring tank having a large liquid depth and a small specific surface area. Was. For this purpose, it is necessary to carry out the reaction at the highest possible vacuum.

On the other hand, the proportion of the unreacted raw material monomer remaining in the polymerization region is usually 5% of the initially used monomer.
As described below, in the transesterification reaction of polycarbonate, it was found that if this small amount of unreacted monomer was distilled out of the system, the reaction rate in the subsequent transesterification reaction was greatly reduced. This is because, among the reaction raw materials, components having a low boiling point are preferentially distilled out of the system, so that the terminal molar balance involved in the reaction is broken and the reaction is inhibited.

When the transesterification reaction rate decreases, the thermal history increases, and the hue of the polymer deteriorates. In order to prevent this, it is essential to use a strict rectification column, and a reflux liquid obtained by condensing a compound mainly composed of a monohydroxy compound generated from the reaction system is returned to the top of the rectification column to ensure separation. It is necessary.

However, in this reaction region, as described above, since the desorption rate of the monohydroxy compound is slow, the concentration of the raw monomer in the vapor generated from the reaction tank is high, and the separation of the monohydroxy compound and the raw monomer is difficult. Turned out to require a considerable number of separation stages.

This means that a non-negligible differential pressure is generated in the rectification column, which causes an increase in the reaction pressure, a reduction in the reaction rate, and a deterioration in the hue of the polymer due to the heat history.

The present inventors have clarified such problems and made intensive studies to solve them. As a result, the use of a rectification column packed with structured packing solves these problems. And found that a polycarbonate having an excellent hue can be obtained.

As rectification columns used in the range of viscosity average molecular weight of 1,000 to 8,000, plate columns such as valve trays, flexi trays, bubble trays, and sieve trays do not greatly impair the efficiency due to scale-up, but have a pressure loss. Is not preferred. In addition, packed towers using random packing such as Raschig rings, pole rings, bell saddles, interlock saddles, McMahons, IMTPs, etc., have a large decrease in efficiency due to scale-up,
The magnitude of the pressure loss is also insufficient, which is not preferable.

The rectification column preferably used in the present invention is a rectification column packed with a structured packing. Such a structured packing is not particularly limited, and a known structured packing is preferably used. For example, slother packing, Mela pack, Interlock and the like can be mentioned.

A rectification column using a through-zer packing will be described below with reference to FIGS. However, the present invention is not limited by the illustration.

FIG. 1A is a perspective view of a rectification column according to the present invention. Numbers 1 and 2 represent corrugated sheets.

FIGS. 1B and 1C show the individual corrugated plates 1 and 2 taken out and viewed from the side. The solid and dotted lines are used to facilitate visual distinction between corrugated sheets.

More specifically, the corrugated plates 1 and 2 have their ridge lines perpendicular to each other.

[0102] The corrugated plates 1 and 2 are such that some of such combinations are put in a cylindrical case to form one set, and several layers are stacked and incorporated into the rectification column. In addition, a cylindrical case is not shown in FIG.

2 (a) is a cross-sectional view of the rectification tower according to the present invention cut from the lateral direction, and FIG. 2 (b) is a part of a cross-sectional view of the rectification tower according to the present invention cut from the vertical direction. (One corrugated plate, ie, one of the cylindrical cases).
In both cases, numbers 1 and 2 represent corrugated sheets as in the case of FIG.

That is, in the rectification column using the through-zer packing, several combinations of the corrugated sheets described above are stacked and incorporated in the rectification column.

The corrugated plate may be a plate, a punching plate or a mesh.

In the present invention, the degree of vacuum in the last reactor in the reactor having the rectification column filled with the ordered packing is preferably 30 Torr or less, and is preferably 20 Torr or less.
More preferably, it is not more than rr.

The viscosity average molecular weight of the polymer after leaving the reaction tank is preferably at least 3,000, more preferably at least 4,000.

The pressure loss of the rectification column packed with the structured packing used in the present invention is preferably 15 Torr or less, more preferably 10 Torr or less.

It is to be noted that a catalyst deactivator can be added to the polycarbonate obtained in the present invention.

As the catalyst deactivator used in the present invention, known catalyst deactivators are effectively used. Among them, ammonium salts and phosphonium salts of sulfonic acid are preferable.
Further, the above salts of dodecylbenzenesulfonic acid such as tetrabutylphosphonium dodecylbenzenesulfonate and the above salts of paratoluenesulfonic acid such as tetrabutylammonium p-toluenesulfonate are preferred. Also, methyl benzenesulfonate as an ester of sulfonic acid,
Ethyl benzenesulfonate, butyl benzenesulfonate, octyl benzenesulfonate, phenyl benzenesulfonate, methyl paratoluenesulfonate, ethyl paratoluenesulfonate, butyl paratoluenesulfonate,
Octyl p-toluenesulfonate, phenyl p-toluenesulfonate and the like are preferably used, and among them, tetrabutylphosphonium dodecylbenzenesulfonate is most preferably used.

The amount of use of these catalyst deactivators is 0.5 to 50 mol, preferably 0.5 to 50 mol, per mol of the polymerization catalyst selected from alkali metal compounds and / or alkaline earth metal compounds. It can be used at a ratio of 10 mol, more preferably at a ratio of 0.8 to 5 mol.

These catalyst deactivators are directly added or dissolved or dispersed in an appropriate solvent and added to and kneaded with a molten polycarbonate. There is no particular limitation on the equipment used to carry out such an operation, but for example, a twin-screw ruder is preferable, and a vented twin-screw ruder is particularly preferable when the catalyst deactivator is dissolved or dispersed in a solvent. used.

In the present invention, additives can be added to the polycarbonate as long as the object of the present invention is not impaired. This additive is preferably added to the molten polycarbonate similarly to the catalyst deactivator. Examples of such an additive include a heat stabilizer, an epoxy compound, an ultraviolet absorber, a release agent, a colorant, Slip agents, anti-blocking agents, lubricants, organic fillers, inorganic fillers and the like can be mentioned.

Of these, heat stabilizers, ultraviolet absorbers, release agents, coloring agents, and the like are particularly commonly used, and two or more of these can be used in combination.

The heat stabilizer used in the present invention includes:
For example, a phosphorus compound, a phenol-based stabilizer, an organic thioether-based stabilizer, a hindered amine-based stabilizer and the like can be mentioned.

As the ultraviolet absorber, a general ultraviolet absorber is used, for example, a salicylic acid ultraviolet absorber, a benzophenone ultraviolet absorber, a benzotriazole ultraviolet absorber, a cyanoacrylate ultraviolet absorber and the like. Can be mentioned.

As the release agent, generally known release agents can be used, for example, hydrocarbon release agents such as paraffins, fatty acid release agents such as stearic acid, and stearamide. Release agents such as fatty acid amides, alcohol release agents such as stearyl alcohol and pentaerythritol, fatty acid ester release agents such as glycerin monostearate and pentaerythritol stearate, and silicone release agents such as silicone oil. And the like.

As the colorant, an organic or inorganic pigment or dye can be used.

The method of adding these additives is not particularly limited. For example, they may be directly added to polycarbonate, or may be prepared and added as master pellets.

[0120]

According to the present invention, a method for producing an aromatic polycarbonate resin by installing two or more reaction vessels in series and reacting an aromatic dihydroxy compound and a carbonic acid diester in the presence / absence of a catalyst. At least one
After installing a rectification column having a reflux mechanism filled with ordered packing in the reaction vessel of the first stage, polymerization was performed while refluxing the bottom liquid of the rectification tower in the reaction vessel, and a prepolymer was generated. By supplying the prepolymer to a subsequent reaction tank and further polymerizing the same, it is possible to provide a method for producing a polycarbonate resin capable of significantly improving the hue of the polymer.

[0121]

The present invention will be described below with reference to examples and comparative examples. It should be noted that this embodiment is for illustrating the present invention, and the present invention is not limited to this embodiment.

In the examples and comparative examples, the viscosity-average molecular weight was determined by measuring the intrinsic viscosity of a 0.7 g / dl methylene chloride solution using an Ubbelohde viscometer, and the viscosity-average molecular weight was determined by the following equation. [Η] = 1.23 × 10 ⁻⁴ × M ^{0.83 As} the measured value of the polymer hue, polycarbonate pellets (short diameter × long diameter × length (mm) = 2.5 × 3.3 ×
3.0) L, a, and b values of ND-100 manufactured by Nippon Denshoku Industries Co., Ltd.
Among the results measured by the reflection method using 1DP, the b value was used as a measure of yellowness.

For the measurement of the terminal hydroxyl group concentration of the polymer,
The terminal hydroxyl group and the terminal phenyl group were measured using 1H-NMR (EX-270, manufactured by JEOL Ltd.) of the chloroform solution of 0.02 g / 0.4 ml at 20 ° C., and the terminal hydroxyl group concentration was measured by the following formula. Terminal hydroxyl group concentration (%) =
(Number of terminal hydroxyl groups / number of all terminals) × 100

[Example 1] Diphenyl carbonate was charged into a melting tank equipped with a stirrer at a ratio of 1.01 mol to 1 mol of 2,2-bis (4-hydroxyphenyl) propane, and nitrogen was added. After the replacement, the mixture was heated and melted at 150 ° C., and the molten mixture was transferred to a raw material storage tank whose temperature was controlled at 150 ° C.

The production of the prepolymer in the preceding reaction tank after the raw material storage tank and the production of the polymer in the latter reaction tank were continuous operations. The former reaction tank was composed of a first vertical reaction tank and a second vertical reaction tank, and the latter reaction tank was composed of one final polycondensation reaction tank.

The details of the continuous operation will be described below.

50k from the raw material storage tank using a metering pump
g / hr continuously into the first vertical reaction vessel and 1 × 10 ⁻⁶ equivalents of sodium phenoxide and 1 × with respect to 1 mol of 2,2-bis (4-hydroxyphenyl) propane. 10 ^-4 equivalents of tetramethylammonium hydroxide was also continuously added to the reactor.

Phenol produced and vaporized in the first-stage vertical reaction tank and partially vaporized raw material (2,2-bis (4-
Hydroxyphenyl) propane and diphenyl carbonate) are continuously rectified in a rectification column filled with random packing (interlox saddle) attached to the reaction tank, and then only phenol is distilled out of the reaction system. The transesterification was allowed to proceed continuously.

In the first-stage vertical reaction tank, the prepolymer temperature was 220 ° C., and the internal pressure of the reaction tank was 13333 Pa (100 T).
orr). In this case, the pressure loss of the rectification column was 10 Torr.

The prepolymer produced in the first vertical reaction tank was continuously extracted from the bottom of the tank using a gear pump, and was continuously fed to the second vertical reaction tank.

The prepolymer discharged from the first vertical reaction tank was taken out of a valve provided on the outlet side of the gear pump, and the viscosity average molecular weight and terminal hydroxyl group concentration were measured. The viscosity average molecular weight was 1500 and the terminal hydroxyl group concentration was 49. %Met.

In the second vertical reaction tank, phenol formed and vaporized in the reaction tank and residual raw materials partially vaporized (2,2-bis (4-hydroxyphenyl) propane and diphenyl carbonate) In the rectification column filled with regular packing (through-the-packing) attached to the reaction tank, the transesterification reaction proceeds continuously while distilling only phenol out of the reaction system after continuous rectification. Was.

In the second stage reaction tank, the prepolymer temperature was 250 ° C., and the internal pressure of the reaction tank was 2000 Pa (15 Torr).
The polymerization was carried out. In this case, the pressure loss of the rectification tower is 5T.
orr.

The prepolymer obtained in the second-stage reaction tank was continuously withdrawn using a gear pump, and was continuously fed to the final-stage polycondensation reaction tank (horizontal uniaxial reaction tank).
The prepolymer was withdrawn from a valve installed on the outlet side of the gear pump, and the viscosity average molecular weight and terminal hydroxyl group concentration were measured. The viscosity average molecular weight was 6000 and the terminal hydroxyl group concentration was 46.
%Met.

The polycondensation reaction was allowed to proceed continuously while all the phenol and the like generated and vaporized in the horizontal single-axis reaction tank at the final stage where the prepolymer was fed was distilled out of the reaction system.

In the final polycondensation reaction tank, polymerization was carried out at a polymer temperature of 270 ° C. and an internal pressure of the reaction tank of 133 Pa (1 Torr).

The polymer obtained in the polycondensation reaction tank at the last stage was continuously extracted using a gear pump, extruded from a die, and then pelletized by a pelletizer.
When the viscosity average molecular weight and the terminal hydroxyl group concentration of the obtained pellet were measured, the viscosity average molecular weight was 15,500, the terminal hydroxyl group concentration was 45%, and the b value of the hue was -0.2.

[Comparative Example 1] A rectifier filled with an irregular packing (interlock saddle) instead of a rectifying tower filled with a structured packing (sluzer packing) in a second vertical reaction tank The same equipment as in Example 1 was used except that a tower was installed.

The reaction was carried out in the same manner as in Example 1 up to the point where the first-stage vertical reaction tank was left.

The prepolymer obtained in the first vertical reaction tank was further continuously fed to the second vertical reaction tank.
Phenol produced and vaporized in the reaction vessel and residual raw materials partially vaporized (2,2-bis (4-hydroxyphenyl) propane and diphenyl carbonate) are mixed with an irregular packing (inter-package) attached to the reaction vessel. Rocks saddle)
After continuously rectifying in a rectification column filled with, the transesterification reaction was allowed to proceed continuously while only phenol was distilled out of the reaction system.

In this case, the pressure loss in the rectification column is 35
Torr, the reaction condition of the second stage was 250
C., and the reactor internal pressure had to be operated at 5999 Pa (45 Torr).

The prepolymer obtained in the second-stage reaction vessel was continuously withdrawn using a gear pump, and was continuously fed to the final-stage polycondensation reaction vessel.

The prepolymer obtained in the second-stage reaction tank was withdrawn from a valve provided on the outlet side of the gear pump, and the viscosity average molecular weight and terminal hydroxyl group concentration were measured. The viscosity average molecular weight was 3,800 and the terminal hydroxyl group concentration was 47%. there were.

The polycondensation reaction was allowed to proceed continuously while all the phenol and the like generated and vaporized in the horizontal reaction tank at the final stage where the prepolymer was fed was distilled out of the reaction system.

In the final polycondensation reaction tank, since the degree of polymerization of the fed prepolymer was low, the polymerization was carried out by increasing the reaction temperature to 292 ° C.

The polymer obtained in the final polycondensation reaction tank was continuously withdrawn using a gear pump, extruded from a die, and then pelletized with a pelletizer.
When the viscosity average molecular weight and the terminal hydroxyl group concentration of the obtained pellet were measured, the viscosity average molecular weight was 15,400, the terminal hydroxyl group concentration was 68%, and the b value was 1.1 for the hue.

Comparative Example 2 The same procedure as in Comparative Example 1 was carried out except that the polymer temperature in the final polycondensation reaction tank was 270 ° C. and the average residence time was 2.6 hours, the viscosity average of the pellets obtained was The molecular weight was 15,400, the terminal hydroxyl group concentration was 65%, and the b value of the hue was 1.4.

[Brief description of the drawings]

FIG. 1 is a perspective view of a rectification column according to the present invention (a), a corrugated sheet 1;
2 (b) and a side view (c) of the corrugated plate 2 are shown.

FIG. 2 shows a sectional view (a) of the rectification column according to the present invention cut in a lateral direction and a sectional view (b) of the rectification column cut in a lateral direction.

[Explanation of symbols]

 1. Corrugated sheet 2. Corrugated sheet

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Toru Sawaki 2-1 Hinodecho, Iwakuni-shi, Yamaguchi Prefecture Teijin Co., Ltd. Inside the Iwakuni Research Center (72) Inventor Katsushi Sasaki 2-1 Hinodecho, Iwakuni-shi, Yamaguchi Prefecture Teijin Shares F-term in the Iwakuni Research Center of the Company (reference)

Claims (7)

[Claims] 1. A method for producing an aromatic polycarbonate resin by installing two or more reaction tanks in series and reacting a reaction mixture containing an aromatic dihydroxy compound and a carbonic acid diester in the presence / absence of a catalyst. In at least one of the reaction vessels in the former stage used for the transesterification initial reaction, a rectification column having a reflux mechanism filled with ordered packing is installed and polymerized to form a prepolymer. A method for producing an aromatic polycarbonate resin, comprising supplying the prepolymer to a subsequent reaction vessel and further polymerizing the same. 2. A method for producing an aromatic polycarbonate resin in which two or more reaction tanks are arranged in series to react a reaction mixture containing an aromatic dihydroxy compound and a carbonic acid diester in the presence / absence of a catalyst. In the transesterification initial reaction, one or more rectification columns having a reflux mechanism filled with ordered packing are prepared at the stage of polymerizing at a reaction tank internal pressure of 100 Torr or less and obtaining a prepolymer having a viscosity average molecular weight of 1000 or more. Using a reaction tank,
A method for producing an aromatic polycarbonate resin, comprising supplying the prepolymer to a subsequent reaction vessel and further polymerizing the same. 3. A method for producing an aromatic polycarbonate resin in which two or more reaction vessels are arranged in series to react a reaction mixture containing an aromatic dihydroxy compound and a carbonic acid diester in the presence / absence of a catalyst. In the transesterification initial reaction, one or more reaction tanks having a rectification column filled with ordered packing are used in the stage of polymerizing at a reaction tank internal pressure of 20 Torr or less to obtain a prepolymer having a viscosity average molecular weight of 4000 or more. A method for producing an aromatic polycarbonate resin, which comprises supplying the prepolymer to a subsequent reaction vessel and polymerizing the prepolymer. 4. The rectification column packed with the structured packing has a pressure loss of 15 Torr or less.
2. The production method according to 2, 3. 5. The reaction vessel in the first stage having a rectification tower is a vertical stirring vessel, and the reaction vessel in the latter stage without a rectification tower is a horizontal stirring vessel. 5. The production method according to 4. 6. The method according to claim 1, wherein the carbonic acid diester is diphenyl carbonate. 7. The process according to claim 1, wherein the catalyst is an alkali metal compound or an alkaline earth metal compound and a nitrogen-containing basic compound.