JP2000128973A - Production of aromatic polycarbonate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a polycarbonate having an excellent color hue. SOLUTION: This is a method for producing an aromatic polycarbonate by the fusion condensation polymerization of a mixture mainly containing a carbonate diester and an aromatic dihydroxyl compound in the presence or absence of a catalyst, wherein the central value of a carbonate diester/aromatic dihydroxyl compound molar ratio is 1.0-1.1, and the accuracy of deviation of the ratio is ±0.005 or smaller.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing an aromatic polycarbonate. More specifically, the present invention relates to a method for efficiently producing an aromatic polycarbonate having excellent hue stability, heat stability, etc., and excellent hue and transparency by a melt polycondensation method.

[0002]

2. Description of the Related Art Aromatic polycarbonate resins are widely known as very useful resins because of their excellent properties such as impact resistance and transparency. As a method for producing the aromatic polycarbonate resin, an interface method in which an aromatic dihydroxy compound and phosgene are reacted in a mixed solution of an organic solvent and an aqueous alkali solution, and an aromatic dihydroxy compound and a carbonic acid diester are used in the presence of a catalyst. There is a melt polycondensation method in which a reaction is carried out under high or reduced pressure in the presence or absence of phenol and the generated phenol is removed out of the system.

[0003]

However, the quality of the polycarbonate obtained by the melt polycondensation method has a problem that it is inferior to the interface method in terms of hue, branching, gel, etc. due to its severe reaction conditions. Various studies have been made to solve the problem. However, at present, satisfactory results have not yet been obtained, and its use has been limited particularly in applications requiring high quality. An object of the present invention is to provide a method for improving the quality of a polycarbonate obtained by a melt polymerization method and producing a polymer suitable for applications requiring high quality such as the optical field.

[0004]

Means for Solving the Problems The present invention is as follows.

[0005] 1. When a mixture mainly containing a carbonic acid diester and an aromatic dihydroxy compound is melt-polycondensed in the presence or absence of a catalyst to produce an aromatic polycarbonate, the molar ratio of the carbonic acid diester to the aromatic dihydroxy compound used Is 1.0 to 1.1.
And the accuracy of the variation of the molar ratio is ±
A method for producing an aromatic polycarbonate, which is within 0.005.

[0006] 2. When a mixture mainly containing a carbonate diester and an aromatic dihydroxy compound is melt-polycondensed in the presence or absence of a catalyst to produce an aromatic polycarbonate, the carbonate diester used is measured using a micro motion flow meter. And the carbonate diester being weighed is at a temperature equal to or higher than its melting point and a temperature range of ± 2.
A method for producing an aromatic polycarbonate, characterized in that the temperature is maintained within the range of ° C.

[0007] 3. The central value of the molar ratio between the carbonate diester and the aromatic dihydroxy compound used is 1.0 to 1.
3. The method for producing an aromatic polycarbonate according to the above item 2, wherein the amount is within the range of 1.

[0008] 4. The carbonate diester to be used is weighed using a micro motion flow meter, and the carbonate diester being weighed is at a temperature equal to or higher than its melting point and has a temperature range of ±
The above 1 characterized in that the temperature is maintained within 2 ° C.
A method for producing the aromatic polycarbonate according to the above.

[0009] 5. A mixture mainly containing a carbonic acid diester and an aromatic dihydroxy compound is melt-polycondensed in the presence or absence of a catalyst to produce an aromatic polycarbonate, and the amount of the aromatic dihydroxy compound used is measured by a weighing vessel. Weighing using a feed rate or a dispensing rate to the measuring tank of 500 kg / min or less,
A method for producing an aromatic polycarbonate, wherein flexible pipes made of a non-metallic material are installed in all pipe connections of the measuring tank.

[0010] 6. The central value of the molar ratio between the carbonate diester and the aromatic dihydroxy compound used is 1.0 to 1.
6. The method for producing an aromatic polycarbonate according to the above item 5, wherein the amount is within the range of 1.

7. The amount of the aromatic dihydroxy compound to be used is measured using a weighing tank, the supply rate or the discharging rate to the weighing tank is set to 500 kg / min or less, and non-metallic metal is connected to all pipe connections of the weighing tank. 2. The method for producing an aromatic polycarbonate according to the above 1, wherein a flexible pipe made of a material is provided.

The aromatic dihydroxy compound used in the present invention includes, for example, bis (4-hydroxyphenyl) methane, 2,2-bis (4-hydroxyphenyl)
Propane, 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-hydroxy Examples thereof include phenyl) sulfide and bis (4-hydroxyphenyl) sulfoxide, and particularly preferred is 2,2-bis (4-hydroxyphenyl) propane.

The diester carbonate used in the present invention includes, for example, 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. Of these, diphenyl carbonate is particularly preferred.

Although the catalyst used in the present invention is not particularly limited, examples of the alkali metal compound include alkali metal hydroxide, hydrogen carbonate, carbonate, acetate, nitrate, nitrite, sulfite, and cyanate. Thiocyanate, stearate, borohydride, benzoate, hydrogen phosphate, bisphenol, phenol salt and the like.

As specific examples, 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 Lithium acid, disodium hydrogenphosphate, dipotassium hydrogenphosphate, dilithium hydrogenphosphate, disodium salt, dipotassium salt, dilithium salt of bisphenol A, phenol sodium salt, potassium salt, lithium salt, etc. A sodium salt of an aromatic dihydroxy compound, for example, a disodium salt of bisphenol A or a sodium salt of an aromatic monohydroxy compound, for example, a sodium salt of phenol is preferably used.

The alkali metal compound as a catalyst is used in such a ratio that the alkali metal element in the catalyst is 1 × 10 ^-3 to 1 × 10 ^-8 equivalents per mole of the aromatic dihydroxy compound. It is preferably used in a ratio of 5 × 10 ⁻⁶ to 1 × 10 ⁻⁸ equivalent, more preferably 5 × 10 ⁻⁶ to 1 × 10 ⁻⁷ equivalent.

If the amount is outside the above range, the properties of the obtained polycarbonate are adversely affected, and the transesterification does not proceed sufficiently to obtain a high-molecular-weight polycarbonate, which is not preferable.

The catalyst used in the present invention includes a nitrogen-containing basic compound. Such as tetramethylammonium hydroxide (Me ₄ NOH), tetraethylammonium hydroxide (Et ₄ NOH), tetrabutylammonium hydroxide (Bu ₄ NOH), benzyltrimethylammonium hydroxide (φ-CH ₂ (M
e) ₃ NOH), alkyl such as hexadecyltrimethylammonium hydroxide, aryl, ammonium hydroxide oxides having an alkyl aryl group, triethylamine, tributylamine, dimethylbenzylamine, tertiary amines such as hexadecyl dimethylamine, or Tetramethylammonium borohydride (Me ₄ NBH ₄ ), tetrabutylammonium borohydride (Bu ₄ NBH ₄ ), tetrabutylammonium tetraphenylborate (Me ₄ NBPh ₄ ), tetrabutylammonium tetraphenylborate (Bu ₄ N)
And basic salts such as BPh ₄ ).
Tetramethylammonium hydroxide (Me ₄ NO
H) is most preferably used.

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. 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).

Germanium (II) acid (germanou)
The alkali metal salt of s acid) is, for example, an acidic or neutral alkali metal salt of monogermanic acid or a condensate thereof, and examples thereof include monosodium germanate (NaHGeO ₂ ).

Germanic (IV) acid (germanic)
The alkali metal salt of acid (acid) is, for example, an acidic or neutral alkali metal salt of monogermanic acid (IV) or a condensate thereof, and examples thereof include monogermanic acid orthogermanate (LiH ₃ GeO ₄ ) orthogermanate. Sodium salt, tetrasodium orthogermanate, disodium digermanate (Na ₂ G
e ₂ O ₅ ), disodium tetragermanate (Na
₂ Ge ₄ O ₉ ) and disodium pentagermanate (Na ₂ Ge ₅ O ₁₁ ).

The above-mentioned polycondensation reaction catalyst is preferably used in such a ratio that the alkali metal element in the catalyst is 1 × 10 ⁻³ to 1 × 10 ⁻⁸ equivalent per mole of the aromatic dihydroxy compound. A more desirable ratio is 5 × 10 ^{−6 with} respect to the same standard.
１1 × 10 ^-8 equivalents, more preferably 5 × 10 ^-6 to 1 × 10 ^-7 equivalents.

In the polycondensation reaction of the present invention, at least one cocatalyst selected from the group consisting of an oxo acid of Group 14 element of the periodic table and an oxide of the same element is optionally used together with the above catalyst. Can coexist.

By using these co-catalysts in a specific ratio, the terminal blocking reaction and the polycondensation reaction rate are not impaired, the branching reaction which is liable to be generated during the polycondensation reaction, or the foreign matter in the apparatus at the time of molding 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 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 co-catalyst should be present in a proportion such that the metal element of Group 14 of the periodic table in the co-catalyst 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 an advantage that the polycondensation reaction and the terminal blocking reaction can be promptly and sufficiently advanced by being used for 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.

As a result of the study by the present inventors, it has been found that the central value of the molar ratio of the carbonic acid diester to the aromatic dihydroxy compound used is preferably in the range of 1.0 to 1.1.

It has also been found that maintaining a molar ratio selected from the above range with high accuracy is extremely important for the production of polycarbonate having good quality. That is, in order to achieve the object of the present invention, it was found that the “accuracy of the variation of the molar ratio” was more preferably ± 0.005, and further preferably ± 0.003. .

The reason why the quality of the polymer including the hue is improved by improving the “accuracy of the fluctuation of the molar ratio” is not obvious. Excessive reaction conditions by increasing the accuracy, for example, to lengthen the polymerization reaction time,
It is possible to avoid conditions that lower the polymer quality, such as increasing the polymerization reaction temperature or increasing the amount of the polymerization catalyst, which leads to improvement in the quality.

In the present specification, the meanings of "aromatic dihydroxy compound used", "carbonic acid diester used", "molar ratio", "center value of molar ratio", and "accuracy of fluctuation of molar ratio" are used. Here's what it does:

That is, since the carbonic diester can be easily handled in a molten state, it can be directly and continuously supplied to a transesterification reaction tank (also referred to as a polymerization tank), but the aromatic dihydroxy compound is in a solid state. To treat these compounds simultaneously or separately,
Once or divided into several times, before the transesterification reaction is started, once received in a monomer mixture preparation tank for preparing a mixture of an aromatic dihydroxy compound and a carbonic acid diester for the production of polycarbonate, and mixed and melted Then, a mixed solution of an aromatic dihydroxy compound and a carbonic acid diester is prepared in a batch system, and the mixed solution is charged into a first transesterification reaction tank (also referred to as an initial polymerization tank). Since the temperature of the preparation tank is kept at about 140 ° C. and the pressure in the tank is also about atmospheric pressure, no transesterification reaction occurs at this stage.

Thus, in the present specification, "aromatic dihydroxy compound used" or "carbonic acid diester used" means an aromatic dihydroxy compound and a carbonic acid diester forming each of these batches. However, when the transesterification reaction is a batch system, the first transesterification reaction tank itself can have a role of a monomer mixture preparation tank.

The "molar ratio" means the molar ratio between the aromatic dihydroxy compound and the carbonic acid diester in the same batch, and the "center value of the molar ratio" is the "molar ratio" for each batch. The value obtained by averaging the values of the “ratio” for the nine batches before and after the fifth batch including the batch as the “fifth batch” is referred to as the “accuracy of the variation in the molar ratio”. Means the value with the larger absolute value.

As a method for achieving the accuracy of the variation of the molar ratio of the present invention, there is no particular limitation, and any method can be used. Correction may need to be performed. In order to avoid this problem, the following method can be preferably used in the present invention.

In the method for producing an aromatic polycarbonate according to the present invention, when preparing a mixture of a diester carbonate and an aromatic dihydroxy compound to be supplied to a polymerization reactor, the amount of the diester carbonate is measured at a temperature not lower than the melting point of the diester carbonate. It is preferable from the viewpoint of the measurement accuracy that good measurement accuracy is obtained by performing the above and that the temperature range of the carbonic acid diester during the measurement is maintained within a fluctuation range of ± 2 ° C. If the fluctuation width is within ± 1 ° C., it is more preferable for the measurement accuracy. Furthermore, when preparing a mixture of the carbonic acid diester and the aromatic dihydroxy compound to be supplied to the polymerization reaction tank, the molten carbonic acid diester is preferably measured using a micromotion flowmeter.

In the method for producing an aromatic polycarbonate according to the present invention, a weight meter is used to measure the aromatic dihydroxy compound when preparing a mixture of the carbonate diester and the aromatic dihydroxy compound to be supplied to the polymerization reaction tank. Preferably, it is used. The weight measuring device is installed in the aromatic dihydroxy compound measuring tank, and the piping laid in the aromatic dihydroxy compound measuring tank is connected to the measuring tank by using a flexible material made of a nonmetallic material. Is preferred. The metering and dispensing rate of the aromatic dihydroxy compound is preferably 500 kg / min or less, more preferably 200 kg / min.

In the method for producing an aromatic polycarbonate according to the present invention, the following method is preferable in order to adjust the molar ratio between the carbonic acid diester and the aromatic dihydroxy compound to the target value with high accuracy. That is, when preparing a mixture of a carbonic acid diester and an aromatic dihydroxy compound to be supplied to the polymerization reaction tank, the amount of the carbonic acid diester necessary for preparing a target mixture of the carbonic acid diester and the aromatic dihydroxy compound at a set molar ratio is reduced. The part is first metered into a monomer mixture preparation tank using a micromotion flowmeter. Next, the required amount of the aromatic dihydroxy compound is supplied from the aromatic dihydroxy compound measuring tank to the whole monomer mixture preparation tank. From the amount of the aromatic dihydroxy compound supplied to the monomer mixture preparation tank, the amount of the carbonate diester required to prepare the target mixture of the molar ratio of the carbonate diester and the aromatic dihydroxy compound is calculated. The amount of carbonic acid diester obtained by subtracting the amount of carbonic acid diester initially added from the obtained required amount of carbonic acid diester is quantitatively supplied to the monomer mixture preparation tank using a micromotion flowmeter.

[0047]

According to the above-mentioned apparatus and operating procedure, it is used for producing an aromatic polycarbonate by melt-polycondensing a mixture mainly containing a diester carbonate and an aromatic dihydroxy compound in the presence or absence of a catalyst. The center value of the molar ratio between the carbonic acid diester and the aromatic dihydroxy compound to a target value in the range of 1.0 to 1.1,
In addition, it has been found that the accuracy of the fluctuation of the molar ratio can be adjusted within ± 0.005, and thereby, a polycarbonate having an excellent hue can be produced.

[0048]

Embodiments will be described below with reference to embodiments. The percentages and parts in the examples are% by weight or parts by weight unless otherwise specified. The physical properties of the polycarbonate obtained in the following Examples were measured as follows.

[Intrinsic viscosity and viscosity average molecular weight] 0.7
The intrinsic viscosity of the g / dl methylene chloride solution was measured using an Ubbelohde viscometer, and the viscosity average molecular weight was determined by the following equation. [Η] = 1.23 × 10 ⁻⁴ M ^0.83

[Color (b value)] Lab of polycarbonate pellets (short diameter × long diameter × length (mm) = 2.5 × 3.3 × 3.0)
The value was measured by the reflection method using Nippon Denshoku Industries ND-1001DP,
The b value was used as a measure of yellowness. The melting point of diphenyl carbonate used in the experiment was 80.2 ° C.

[Example 1] Melt polycondensation of an aromatic polycarbonate was carried out using the following reaction equipment.
An outer jacket, a diester carbonate storage tank for storing molten diester carbonate, a diester carbonate supply pump capable of supplying the diester carbonate to the monomer mixture preparation tank, an aromatic dihydroxy compound storage tank for receiving an aromatic dihydroxy compound powder, and a load cell (Weight weighing device), an aromatic dihydroxy compound measuring tank having a flexible structure in which all connecting portions of piping are made of aramid cloth, and an aromatic dihydroxy compound and a carbonic acid diester are weighed and heated and melted. To prepare a monomer mixture preparation tank capable of stirring and mixing, a raw material supply tank equipped with a raw material pump capable of receiving raw materials prepared from the monomer mixture preparation tank and continuously supplying a constant amount of raw materials to the initial polymerization tank, and preparing a polymerization catalyst. Catalyst preparation tank, the catalyst prepared from the catalyst preparation tank The solution accept, the catalyst feed vessel equipped with an catalyst pump capable of quantitatively feeding catalyst solution to an initial polymerization tank using a polymerization apparatus having a ancillary facilities was performed continuously melt polycondensation reaction.

The pipe connecting the diester carbonate storage tank and the monomer mixture preparation tank is provided with an external jacket. The pipe is provided with a micro motion flow meter, an automatic valve which can be opened and closed by the indicated value, and a pipe. A thermometer is installed to measure the temperature of the carbonic acid diester inside.

These initial polymerization tanks are provided with 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. The reaction solution in the initial polymerization tank is continuously supplied to the latter polymerization tank by a gear pump.

The late polymerization tank is a horizontal stirring tank, does not have a rectification column, and has a jacket provided on the whole. The aromatic polycarbonate that has exited the late polymerization tank is continuously extruded from a die, turned into strands in a cooling bath, and then pelletized by a cutter.

The operating conditions of the melt polycondensation are shown below. Bisphenol A was used as the aromatic dihydroxy compound, and diphenyl carbonate was used as the carbonic acid diester.

The target value of the molar ratio between the carbonic acid diester and the aromatic dihydroxy compound in the mixture of the monomeric carbonic acid diester and the aromatic dihydroxy compound before being supplied to the polymerization reactor was 1.010.

The diphenyl carbonate storage tank has an internal temperature of 8
Maintained at 5 ± 0.5 ° C. Hot water of 85 ± 0.5 ° C. was flowed through the outer jacket of the pipe connecting the diphenyl carbonate storage tank and the monomer mixture preparation tank.

First, 4 g of diphenyl carbonate was stored in the storage tank.
Diphenyl carbonate was supplied to the monomer mixture preparation tank at a charge setting of 00.0 kg. The internal temperature of the pipe connecting the diphenyl carbonate storage tank and the monomer mixture preparation tank being supplied was within a range of 85 ± 0.4 ° C.

Next, bisphenol A was weighed from the aromatic dihydroxy compound storage tank to the aromatic dihydroxy compound measurement tank at a measurement value setting of 527.6 kg. The time required for weighing was about 3 minutes. The weighed bisphenol A was supplied to the monomer mixture preparation tank over a period of about 3 minutes, and mixed and dissolved by stirring. After dissolution, diphenyl carbonate was supplied from the diphenyl carbonate storage tank to the monomer mixture preparation tank at an input amount of 100.0 kg, and the mixture was stirred and mixed. The internal temperature of the pipe connecting the diphenyl carbonate storage tank and the monomer mixture preparation tank during supply is 85 ± 0.4
° C.

The molar ratio of diphenyl carbonate to bisphenol A in the prepared monomer mixture was determined by liquid chromatography to be 1.010. The monomer mixture thus adjusted was transferred to a raw material supply tank.

A disodium salt of bisphenol A was used as a polymerization catalyst. The catalyst, in the catalyst preparation tank,
Phenol / water = so that the catalyst concentration becomes 30 ppm
It was dissolved in a 90/10% by weight mixture. The catalyst solution thus adjusted was transferred to a catalyst supply tank.

The amount of raw materials supplied to the initial polymerization tank was 50 kg / h.
r, the flow rates of the raw material supply pump and the catalyst solution supply pump were adjusted so that the supply amount of the catalyst solution was 0.29 kg / hr, and continuous melt polymerization was performed for 500 hours. During the continuous melt polymerization, the monomer mixture as a raw material was prepared by repeating the procedure described above. During that time, the number of times the monomer mixture was prepared was 25 times. Therefore, the number of data of the central value of the molar ratio and the accuracy of the fluctuation of the molar ratio obtained by this series of experiments was 17 excluding 8 batches before and after.

Diphenyl carbonate and bisphenol A in the monomer mixture prepared for each monomer mixture preparation
Table 1 shows the monomer molar ratio determined by liquid chromatography and the accuracy of the fluctuation of the molar ratio.

The operation conditions of each polymerization tank are as follows: the initial polymerization tank has an internal temperature of 250 ° C., a degree of vacuum of 30 Torr, and the late polymerization tank has a
° C and the degree of vacuum were 0.5 Torr.

Polycarbonate samples were taken at the end of the late polymerization tank at a frequency of once / day and evaluated for quality. The results are shown in Table 1.

Example 2 In the monomer mixture preparation procedure of Example 1, diphenyl carbonate was first supplied to the monomer mixture preparation tank at a feed rate of 500.0 kg, and then the aromatic dihydroxy compound was supplied from the aromatic dihydroxy compound storage tank. Add bisphenol A to the compound measuring tank
Weighed with a 7.6 Kg weighing setting. The time taken for metering and feeding was both about 3 minutes.

The number of times the monomer mixture was prepared was 25 times. Table 1 shows the monomer molar ratios determined by liquid chromatography for the molar ratios of diphenyl carbonate and bisphenol A in the monomer mixtures prepared for each monomer mixture preparation, and the accuracy of the fluctuations in the molar ratios.

The internal temperature of the pipe connecting the diphenyl carbonate storage tank and the monomer mixture preparation tank during the preparation of the monomer mixture was within a range of 85 ± 0.4 ° C.

A polycarbonate sample was taken at the end of the late polymerization tank at a frequency of once / day and evaluated for quality. The results are shown in Table 1.

Comparative Example 1 The same as Example 1 except that the micromotion flow meter attached to the pipe connecting the diester carbonate storage tank and the monomer mixture preparation tank to the reaction equipment of Example 1 was changed to a volume flow meter. Continuous melt polymerization was performed for 500 hours under the same operating conditions as the reaction equipment.

The number of times the monomer mixture was prepared was 25 times. Table 1 shows the monomer molar ratios determined by liquid chromatography for the molar ratios of diphenyl carbonate and bisphenol A in the monomer mixtures prepared for each monomer mixture preparation, and the accuracy of the fluctuations in the molar ratios.

The internal temperature of the pipe connecting the diphenyl carbonate storage tank and the monomer mixture preparation tank during the preparation of the monomer mixture was within the range of 85 ± 0.4 ° C.

Polycarbonate samples were taken at the end of the late polymerization tank at a frequency of once / day and evaluated for quality. The results are shown in Table 1.

[Comparative Example 2] The same reaction equipment as in Example 1 except that a SUS flexible pipe was used at the connection part of the pipe connected to the aromatic dihydroxy compound measuring tank. Under the same operating conditions, continuous melt polymerization was performed for 500 hours.

The number of times the monomer mixture was prepared was 25 times. Table 1 shows the monomer molar ratio and the accuracy of fluctuation of the molar ratio, which were determined by liquid chromatography for the molar ratio of diphenyl carbonate and bisphenol A in the monomer mixture prepared for each monomer mixture preparation.

The internal temperature of the pipe connecting the diphenyl carbonate storage tank and the monomer mixture preparation tank during the preparation of the monomer mixture was within the range of 85 ± 0.4 ° C.

A polycarbonate sample was collected at the outlet of the late polymerization tank at a frequency of once / day and evaluated for quality. The results are shown in Table 1.

[0078]

[Table 1]

Continued on the front page (72) Inventor Toru Sawaki 2-1 Hinode-cho, Iwakuni-shi, Yamaguchi Pref. Teijin Limited Iwakuni Research Center (72) Inventor Katsushi Sasaki 2-1 Hinode-cho, Iwakuni-shi, Yamaguchi Pref. F-term in the center (reference) 4J029 AA09 AB04 AB05 AD01 AE01 BB04A BB05A BB10A BB12A BB13A BB13B BF14A BF14B BG05X BG08X BG24X BH02 DB11 J13J01J03 J031 J01J11F KD01 KE02 KE05 KJ05 KJ08 LA20 LB09 LB10

Claims (7)

[Claims] 1. A method for producing an aromatic polycarbonate by melt-polycondensing a mixture mainly containing a diester carbonate and an aromatic dihydroxy compound in the presence or absence of a catalyst. The central value of the molar ratio with the compound is in the range of 1.0 to 1.1, and the accuracy of the fluctuation of the molar ratio is ± 0.
A method for producing an aromatic polycarbonate, which is within 005. 2. A mixture mainly comprising a diester carbonate and an aromatic dihydroxy compound is melt-polycondensed in the presence or absence of a catalyst to produce an aromatic polycarbonate. A method for producing an aromatic polycarbonate, comprising weighing with a meter and maintaining the carbonate diester being weighed at a temperature equal to or higher than its melting point and within a temperature range of ± 2 ° C. 3. The production of an aromatic polycarbonate according to claim 2, wherein the central value of the molar ratio between the carbonic acid diester and the aromatic dihydroxy compound is in the range of 1.0 to 1.1. Method. 4. A carbonate diester to be used is weighed using a micro motion flow meter, and the carbonate diester being weighed is at a temperature not lower than its melting point and a temperature range of ± 2 ° C.
The method for producing an aromatic polycarbonate according to claim 1, wherein the temperature is maintained within the range. 5. An amount of an aromatic dihydroxy compound used in producing an aromatic polycarbonate by melt-polycondensing a mixture mainly containing a diester carbonate and an aromatic dihydroxy compound in the presence or absence of a catalyst. Is weighed using a weighing tank, the feed rate or the dispensing rate to the weighing tank is set to 500 kg / min or less, and flexible pipes made of a nonmetallic material are installed at all the pipe connections of the weighing tank. A method for producing an aromatic polycarbonate. 6. The production of an aromatic polycarbonate according to claim 5, wherein the central value of the molar ratio between the carbonic acid diester and the aromatic dihydroxy compound used is in the range of 1.0 to 1.1. Method. 7. The amount of the aromatic dihydroxy compound to be used is measured using a gravimetric measuring tank, the feeding rate or the discharging rate to the measuring tank is set to 500 kg / min or less, and all pipe connections of the measuring tank are performed. 2. The method for producing an aromatic polycarbonate according to claim 1, wherein a flexible pipe made of a nonmetallic material is installed in the portion.