JP3508488B2 - Method for producing aromatic polycarbonate - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing an aromatic polycarbonate. Specifically, it relates to a method for producing an aromatic polycarbonate by subjecting an aromatic dihydroxy compound and a diaryl carbonate having a small content of a specific impurity to a melt polycondensation reaction. According to the present invention, a commercial-quality aromatic polycarbonate having an excellent color tone can be produced with high productivity by a transesterification method.

[0002]

2. Description of the Related Art Aromatic polycarbonates are widely used as engineering plastics by taking advantage of their excellent transparency, impact resistance, heat resistance and dimensional stability. As a production method thereof, a so-called interfacial polymerization method in which phosgene and a bisphenol compound are reacted in a two-phase solvent of methylene chloride / water is mainly used. In recent years, the carcinogenicity of methylene chloride has become a concern, and in response to the tightening of regulations on waste water and air pollution of methylene chloride, the polymerization method by transesterification of bisphenol compounds and diaryl carbonate was reviewed. ing.

In the case of the transesterification method, which is different from the interfacial polymerization method, the reaction is carried out at a high temperature and in the presence of a catalyst.
A factor in avoiding coloration is to polymerize at the lowest possible temperature and with the lowest possible catalyst amount to achieve the target molecular weight. In order to achieve this object, the purity of the raw materials used for polymerization is extremely important, and in JP-A-2-175722, the total content of hydrolyzable chlorine as impurities in the raw materials is 3 p.
A method using a polymerization raw material of pm or less has been proposed. Further, JP-A-4-100824 proposes a method of using a diaryl carbonate having a chlorine content of 0.05 ppm or less and a xanthone content of 10 ppm or less without using a polymerization catalyst. Furthermore, JP-A-7-258
JP-A-30 proposes a refining method of reducing the hydrolyzable chlorine content to 5 ppm or less by heating and decompressing a carbonic acid diester in the presence of aluminosilicate, and a melt polymerization method using a raw material refined by this method. ing.
As a specific chlorine-based impurity, JP-A-5-262872 proposes a polymerization method characterized in that the content of chlorine based on chloroformate in carbonic acid diester is 30 ppm or less.

[0004]

However, all of the above methods reduce the content of hydrolyzable chlorine compounds, but among them, the combination of impurity species that significantly poisons the catalyst and the reduction thereof are Since it was insufficient, the polymerization had to be carried out using an excessive amount of catalyst, and the quality was not sufficiently satisfactory. It is an object of the present invention to provide a method for producing a polycarbonate of excellent quality at a cost advantage and with high productivity by reducing the amount of catalyst used for the polymerization in the transesterification method to a necessary and sufficient minimum amount.

[0005]

Means for Solving the Problems As a result of intensive investigations by the present inventors on the impurities contained in the raw material diaryl carbonate in order to solve the above-mentioned problems, as a result, the poisoning effect of the catalyst becomes remarkable. Based on this finding, we have established a method for significantly reducing the amount of catalyst and improving the quality, and have completed the present invention. It was

That is, the gist of the present invention is to provide a method of producing an aromatic polycarbonate by subjecting an aromatic dihydroxy compound and a diaryl carbonate to a melt polycondensation reaction in the presence of an ester exchange catalyst to produce an aromatic polycarbonate. A method for producing an aromatic polycarbonate, characterized in that a diaryl carbonate having a content of 30 ppb or less and a total nitrogen content of nitrogen-containing impurities of 1.0 ppm or less is used. Hereinafter, the present invention will be described in detail.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The aromatic dihydroxy compound used in the present invention is a compound represented by the general formula (1).

[0008]

[Chemical 1]

(In the formula, A is a single bond, a linear, branched or cyclic divalent hydrocarbon group which may have a substituent having 1 to 15 carbon atoms, -O-, -S. -, -CO-, -SO-
Or —SO ₂ —, X and Y each independently represent halogen or a hydrocarbon group having 1 to 6 carbon atoms, and
And q is an integer of 0 to 2)

Some typical examples of the aromatic dihydroxy compound represented by the formula (1) are, for example, bis (4-hydroxyphenyl) methane, 2,2-bis (4-hydroxyphenyl) propane and 2,2. -Bis (4-hydroxy-3-methylphenyl) propane, 2,2-bis (4
-Hydroxy-3-t-butylphenyl) propane,
2,2-bis (4-hydroxy-3,5-dimethylphenyl) propane, 2,2-bis (4-hydroxy-3,
5-dibromophenyl) propane, 4,4-bis (4-
Bisphenols such as hydroxyphenyl) heptane and 1,1-bis (4-hydroxyphenyl) cyclohexane; 4,4′-dihydroxybiphenyl, 3,3 ′,
Biphenols such as 5,5'-tetramethyl-4,4'-dihydroxybiphenyl; bis (4-hydroxyphenyl) sulfone, bis (4-hydroxyphenyl) sulfide, bis (4-hydroxyphenyl) ether, bis (4- Hydroxyphenyl) ketone and the like. Of these, 2,2-bis (4-hydroxyphenyl) propane is preferable.

Two or more kinds of these compounds may be used in combination (copolymer), and when a branched aromatic polycarbonate is to be produced, a small amount of trihydric or higher polyhydric phenol is copolymerized. You can also Further, for the purpose of further improving the thermal stability and hydrolysis resistance of the aromatic polycarbonate produced, pt-butylphenol, pt-octylphenol, pt-octylphenol and pt-octylphenol are used for the purpose of sealing the hydroxyl terminal. It is also possible to use monohydric phenols such as millphenol.

The diaryl carbonate compound used in the present invention is a compound represented by the general formula (2).

[0013]

[Chemical 2]

(In the formula, R ¹ and R ² each independently represent an alkyl group having 1 to 10 carbon atoms or an alkoxy group, and m and n are integers of 0 to 2)

Specific examples of the compound of the formula (2) include diphenyl carbonate, ditolyl carbonate, dixylyl carbonate, bisbutylphenyl carbonate, bisnonylphenyl carbonate, bismethoxyphenyl carbonate and bisbutoxyphenyl carbonate. be able to. Among these, diphenyl carbonate is preferable. These diaryl carbonate compounds are generally used in excess with respect to 1 mol of the aromatic dihydroxy compound.
It is desirable to use it in an amount of 1.30 mol, preferably 1.02 to 1.20 mol.

As the method for synthesizing the diaryl carbonate compound, a method of synthesizing dimethyl carbonate or the like by a transesterification reaction with a hydroxyaryl compound or a phosgene and / or a so-called phosgene dimer or trimer and / or a phosgene derivative such as aryl chloroformate is used. A method by a phosgenation reaction with a hydroxyaryl compound is known as a typical one, but the present invention is not particularly limited by its synthetic method.
By the way, in the phosgenation, the present invention is particularly effective because dehydrochlorination, sodium dechlorination, potassium dechlorination and the like are generally performed in the presence of a nitrogen-containing basic catalyst such as triethylamine or pyridine as a catalyst.

Regarding the method for synthesizing diaryl carbonate, in the sense that a final method of the present invention is to establish a method for polymerizing a polycarbonate having excellent quality with excellent cost and productivity, the raw material synthesis It is considered that the method by phosgenation, which produces a small amount of isomers by-produced in the process and causes coloration, and consequently results in a small cost of the raw material purification step, is superior in terms of quality and cost. The method for synthesizing the diaryl carbonate preferably used in the present invention includes, for example, a nitrogen-containing basic compound containing an aromatic monohydroxy compound and phosgene or aryl chloroformate, and more preferably an aromatic heterocyclic nitrogen-containing basic compound. The reaction mixture produced by reacting in the presence of the compound is brought into contact with warm water at 80 to 95 ° C., the aqueous phase and the organic phase are separated again, and the diaryl carbonate is recovered from the separated organic phase by distillation. Is mentioned.

In the present invention, the easily water-soluble chlorine-based impurities contained in the diaryl carbonate are those whose chlorine content is analyzed by the following method. That is, the precisely weighed diaryl carbonate (5 g) was dissolved in purified toluene (10 ml) under heating, ultrapure water (10 ml) was added, and the mixture was stirred at room temperature for 10 minutes (magnetic stirrer 10
(00 rpm), and then the chlorine in the aqueous phase is analyzed by ion chromatography.

As disclosed in JP-A-5-262872, as the Cl analyzed by such a method, there is almost no organic chlorine such as that based on chloroformate, and its main component is Cl. Is amine / hydrochloride or N
It is considered to be hydrochloric acid salt such as aCl or KCl or hydrochloric acid itself. The chlorine content of these easily water-soluble chlorine-based impurities in the present invention (hereinafter abbreviated as Cl content) is 30 ppb or less, preferably 20 ppb or less, and more preferably 15 ppb.
It is the following. If the Cl content exceeds 30 ppb, the initial polymerization activity decreases, so the polymerization degree cannot be increased unless an excess catalyst is added or the number of terminal OH groups that adversely affect the quality is increased.

In the present invention, the total nitrogen content of nitrogen-containing impurities contained in the diaryl carbonate (hereinafter referred to as total N
Content and abbreviations) are, for example, Tota manufactured by Mitsubishi Chemical Corporation.
It is a measured value measured by a so-called total nitrogen analyzer such as 1 Nitrogen Analyzer TN-05. The total N content of these nitrogen-containing impurities in the present invention is 1.
It is preferably 0 ppm or less, preferably 0.7 ppm or less, and more preferably 0.5 ppm or less. When the total N content exceeds 1.0 ppm, the initial polymerization rate decreases, so an excessive amount of catalyst is added or the terminal OH which adversely affects the quality.
The degree of polymerization does not increase unless the number of groups is increased.

In the present invention, the easily water-soluble chlorine-based impurities and the nitrogen-containing impurities synergistically affect the polymerization, and the Cl amount is 30 p
Even if it is less than pb, if the total N content exceeds 1.0 ppm, the initial polymerization rate decreases, while the total N content is 1.0
Even if the amount is less than or equal to ppm, even if the Cl amount exceeds 30 ppb, the polymerization rate decreases and the effect of the present invention cannot be obtained.
This is because the weakly basic nitrogen-containing impurities remaining in the synthesis process of diaryl carbonate form a salt with hydrochloric acid, etc., and the volatilization in the polymerization process is reduced compared to the inorganic acid itself, or the acid with the basic catalyst used in the polymerization is reduced. -It is presumed that the poisoning action on the catalyst is strengthened due to the change of the base interaction, etc., but the details are not clear.

Known catalysts and the like are used as the catalyst used for transesterification in the present invention. Among them, a basic catalyst is preferable, and for example, a transesterification catalyst of an alkali metal or an alkaline earth metal or a nitrogen-containing base. A transesterification catalyst such as a basic compound or a phosphorus-containing basic compound is used. Specific examples of the alkali metal and alkaline earth metal compounds preferably include organic acid salts, inorganic acid salts, acid compounds, hydroxides, hydrides or alcoholates of alkali metals and alkaline earth metals.

More specifically, examples of the alkali metal compound include sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium hydrogen carbonate, potassium hydrogen carbonate, lithium hydrogen carbonate, sodium carbonate, potassium carbonate, lithium carbonate, and bisphenol A. Disodium salt, dipotassium salt, dilithium salt, phenol sodium salt, potassium salt, lithium salt, cesium hydroxide, cesium carbonate, cesium hydrogen carbonate and other inorganic cesium salts, cesium acetate, cesium stearate and other organic acids Examples thereof include cesium salts, cesium alcoholates such as cesium methylate and cesium ethylate, cesium phenolate, and phenolic cesium salts such as cesium salt of bisphenol A.

Further, as the alkaline earth metal compound,
Specifically, calcium hydroxide, barium hydroxide, magnesium hydroxide, strontium hydroxide, calcium hydrogen carbonate, barium hydrogen carbonate, magnesium hydrogen carbonate, strontium hydrogen carbonate, calcium carbonate, barium carbonate,
Examples thereof include magnesium carbonate and strontium carbonate. These compounds may be used alone or in combination.

In the present invention, a basic compound may be used as a catalyst together with the above-mentioned alkali metal compound and / or alkaline earth metal compound. Such basic compounds include, for example, nitrogen-containing basic compounds and phosphonium hydroxy compounds that are easily decomposable or volatile at high temperature, rarely remain in the final aromatic polycarbonate, and do not adversely affect physical properties such as hue. Examples of the compound include the following compounds.

The nitrogen-containing basic compound is tetramethyi.
Lumonium hydroxide (Me _FourNOH), Tetra
Ethyl ammonium hydroxide (Et_FourNOH) etc.
Ammo having alkyl, aryl, araryl groups, etc.
Nium hydroxides, trimethylamine, triethyl
Tertiary amines such as amines, R₂NH (where R is methyl
Alkyl such as ru and ethyl, ant such as phenyl and toluyl
Group, etc.) secondary amines, RNH
₂(Wherein R is the same as above)
Compounds, 2-methylimidazole, 2-phenylimidazo
Imidazoles such as alcohol, sodium nitrilotriacetate, etc.
Iminocarboxylic acid derivative or salt thereof, or ammoni
A, Tetramethylammonium borohydride (Me
_FourNBH_Four), Tetrabutylammonium borohydra
Id (Bu_FourNBH_Four) And the like basic salts.

Examples of the phosphonium hydroxide compound include tetraethylphosphonium hydroxide, tetrabutylphosphonium hydroxide, tetraphenylphosphonium hydroxide, methyltriphenylphosphonium hydroxide and allyltriphenylphosphonium hydroxide. Among these, tetraalkylammonium hydroxide, tetrabutylphosphonium hydroxide and tetraphenylphosphonium hydroxide are preferably used.

In the case of an alkali metal compound and / or an alkaline earth metal compound, the amount of catalyst used is usually 1 × 10 ^-5 to 1 × 1 with respect to 1 mol of the aromatic diol compound.
It is used in an amount of 0 ^-4 mol, preferably 1 x 10 ^-7 to 1 x 10 ^-5 mol, and in the case of a basic compound, it is usually 1 x 10 ^-7 per 1 mol of the aromatic diol compound. ~ 1 x 10
^-1 mol, preferably used in an amount of 1 x 10 ^-6 to 1 x 10 ^-2 mol.

The polymerization process used in the present invention is not particularly limited, and a polymerization process generally used for transesterification reaction can be adopted. For example, a vertical type and / or a horizontal type polymerization device equipped with a stirring device may be used in an appropriate combination of one or several, and may be a batch type or a continuous type, 170 to 30
0 ° C, more preferably 200 to 280 ° C, even more preferably 2
There is a method of increasing the temperature in the temperature range of 10 to 275 ° C., and also increasing the molecular weight by appropriately increasing the polymerization pressure between the normal pressure and the full vacuum with the progress of the polymerization. Particularly in the latter stage of the polymerization, where the degree of polymerization increases and the viscosity increases, a high-viscosity type reactor such as a horizontal reactor having excellent interfacial renewal property is preferably used. Further, as another method, a method in which the produced polymer is once crystallized by a method such as heat treatment or contact with a solvent in the latter stage of the polymerization and then solid-phase polymerization is also applicable.

The molecular weight of the aromatic polycarbonate obtained by the production method of the present invention shows mechanical properties that can be practically used as a film obtained by a molding material obtained by resin molding such as injection molding or extrusion molding or a coating. Therefore, the viscosity average molecular weight is 11,000 or more, more preferably 12,000 or more, and further preferably 13,000 or more. When the viscosity average molecular weight is less than 11,000, it is extremely brittle and cannot be used as a resin material. The upper limit of the molecular weight is not particularly limited, but in consideration of moldability and film-forming property, the viscosity average molecular weight is generally 50,000 or less, more preferably 40,000 or less, and further preferably 35,000 or less. When the viscosity average molecular weight exceeds 50,000, the viscosity is so high that molding with a general molding machine becomes difficult.

The aromatic polycarbonate obtained by the production method of the present invention includes a catalyst stabilizer, a heat resistance stabilizer, an ultraviolet absorber, a release agent, an antistatic agent, a slip agent, an antiblocking agent, a lubricant and an antifogging agent. , Additives such as colorants, fluidity improvers, organic reinforcing fillers, inorganic reinforcing fillers, etc. can be blended and used. Such additives can be added to the aromatic polycarbonate in a molten state, or the aromatic polycarbonate once pelletized can be remelted and added. The remelting is preferably performed in an inert gas atmosphere. It can also be used by blending with other resins such as ethylene / vinyl acetate copolymer, polyamide, polystyrene, acrylonitrile / butadiene / styrene copolymer, polyester polypropylene and the like.

[0032]

[Examples] The present invention will be specifically described below with reference to Examples, but the present invention is not limited to these Examples as long as the gist thereof is not exceeded. The obtained polycarbonate was analyzed according to the following measuring method.

(1) Viscosity average molecular weight (Mv) Using a Ubbelohde viscometer, at 20 ° C. in methylene chloride.
The intrinsic viscosity [η] was measured, and the viscosity average molecular weight (Mv) was calculated from the following formula.

[0034]

[Equation 1] [η] = 1.23 × 10 ⁻⁴ × (Mv) ^0.83

(2) Solution hue A 16.7% methylene chloride solution was used with a diameter of 25 mm and a height of 55.
The tristimulus value XYZ, which is the absolute value of the color, is measured with a color tester (SC-1-CH manufactured by Suga Test Instruments Co., Ltd.) in a mm cell made of glass, which is an index of yellowness according to the following relational expression. The YI value was calculated. It should be noted that the larger the YI value, the more the color is shown.

[0036]

[Equation 2] YI = (100 / Y) × (1.28X-1.96Z)

(3) Easily water-soluble Cl content 5 g of raw material diphenyl carbonate was added to 10 ml of toluene and dissolved at 60 ° C., 10 ml of ultrapure water (ion-exchanged water containing no Cl) was added, and the mixture was stored in a thermostatic chamber at 23 ° C. After stirring for 10 minutes at 1000 rpm using a tic stirrer, chlorine in the aqueous phase was analyzed and determined by ion chromatography.

(4) Approximately 2 g of the total N-content starting material diphenyl carbonate was weighed and completely dissolved by adding toluene, and the volume was adjusted to 10 ml. 20 μl of this solution was TotalNitr manufactured by Mitsubishi Chemical Corporation.
ogen Analyzer TN-05 was infused with total N
The content was determined.

(Synthesis example 1 of diphenyl carbonate) A glass reaction vessel with a jacket connected to an oil circulation type external heating device (internal volume: 1 liter, actual liquid 700).
Three overflow pipes were installed at the position of ml). An exhaust pipe with a condenser for removing the generated hydrochloric acid gas to the outside of the system was connected to the second and third reaction vessels. About 700 ml / hr (phenol 71 was added) of molten phenol which had been added with 5 mol% of pyridine and stirred beforehand.
The temperature was raised to 150 ° C. while continuously supplying 6 g / hr and 30 g / hr of pyridine) to the first reaction vessel. While sufficiently stirring, phosgene (361 g / hr) at a 0.48 molar ratio of the phenol to be fed was continuously fed to the first reaction vessel.

The reaction mixture flowing out of the first reaction vessel is
It was supplied to the second reactor through the overflow pipe, and the reaction mixture flowing out from the second reactor was similarly supplied to the third reactor. The reaction mixture flowing out of the third reactor was withdrawn into a polypropylene receiver. A nitrogen gas blowing tube was installed in the third reactor, and 70 Nl / hr of nitrogen gas was continuously supplied into the reaction mixture. Reaction mixture extracted after the composition was sufficiently stabilized (composition: diphenyl carbonate 89% by weight, phenol 6% by weight, pyridine hydrochloride 5% by weight, phenyl chloroformate undetected) 1
kg was placed in a jacketed glass reaction container connected to an oil circulation type external heating device, and the temperature was raised to 85 ° C. After adding 372 g of a sodium hydroxide aqueous solution having a concentration of 5% by weight which had been heated to 85 ° C., the mixture was stirred for 5 minutes in a two-stage disk turbine blade, and then allowed to stand for 30 minutes, and then the aqueous phase and the organic phase were separated. I pulled it out. The pH after the addition of the aqueous sodium hydroxide solution was 9.

The extracted organic phase was placed again in a glass reaction container with a jacket connected to an oil circulation type external heating device, and the temperature was raised to 85 ° C. 300 g of demineralized water that had been heated to 85 ° C. was added, the mixture was stirred for 5 minutes with the same stirring blade as described above, allowed to stand for 5 minutes, and then the aqueous phase and the organic phase were extracted separately. This operation was repeated again to collect the organic phase. Sulzer Packing (Sumitomo Heavy Industries) 10
The separated organic phase was purified by distillation in a vacuum distillation column filled with pieces. More specifically, the degree of vacuum is 20 to 40 Torr, the temperature of the oil bath is about 220 ° C., the top temperature is 50 to 80 ° C., and the free form pyridine and phenol are distilled off.
orr, oil bath temperature about 230 ℃, top temperature 150
At ℃, 750 g of purified diphenyl carbonate was obtained. The diphenyl carbonate thus obtained had a water-soluble Cl content of 10 ppb and a total N content of 0.03 ppm.
Met. Further, the diaryl carbonate obtained by the completely same method except that the washing and separating step with the 85 ° C. demineralized water in the above-mentioned synthesis example was omitted and the washing and separating were performed once, the easily water-soluble Cl content was 10 to 15 ppb depending on the lot. A total N content in the range of 0.19 to 0.54 ppm was obtained. The diphenyl carbonate thus obtained was used in Examples 1 to 6 below.

(Synthesis example 2 of diphenyl carbonate) Synthesis was carried out in the same manner as in synthesis example 1 except that the stirring was carried out by two steps of paddle blades consisting of four flat plates in the washing with the alkaline aqueous solution of synthesis example 1 and demineralized water. The easily water-soluble Cl content contained in the purified diphenyl carbonate was 110 ppb, and the total N content was 0.52 ppm. The diphenyl carbonate thus obtained was used in Comparative Examples 5 to 6 below.

(Synthesis example 3 of diphenyl carbonate) 1050 g of diphenyl carbonate manufactured by Bayer was distilled under the conditions of a heat medium temperature of 260 ° C., an inner temperature of 190 ° C., a top temperature of 180 ° C. and a vacuum degree of 10 Torr to obtain 950 g of purified diphenyl carbonate. The diphenyl carbonate thus obtained had an easily water-soluble Cl content of 33 ppb and a total N content of 1.15 ppm. This was used in Comparative Example 1 below.

(Synthesis example 4 of diphenyl carbonate) Diphenyl carbonate purified by the same method as in synthesis example 3 except that 500 ml of 1N NaOH was added to 1050 g of diphenyl carbonate manufactured by Bayer in the distillation purification of synthesis example 3 The content was 14 ppb and the total N content was 1.28 ppm. Comparative Example 2 below
Used for ~ 4.

Example 1 182.6 g (0.8 mol) of bisphenol A, Cl content and total N content of 10 ppb and 188.5 g (0.88 mol) of diphenyl carbonate of 0.03 ppm, respectively, and 0.1 as a transesterification catalyst. 50 μl (0.4 μmol) of a 26% cesium carbonate aqueous solution was put into a glass flask equipped with a stirrer and a distillation device having an internal volume of 500 ml, and the contents of the reaction vessel were replaced with nitrogen gas at 210 ° C. under a nitrogen gas atmosphere. Dissolved. After the contents have completely dissolved, 210
This state was maintained at 0 ° C. and normal pressure for 1 hour. Then, the pressure in the reactor was gradually lowered to 100 Torr to distill phenol, and this state was maintained for 1 hour. The amount of distillate distilled during this period is shown in Table 1 as the amount of initial distillate as a guide for the initial polymerization rate. Thereafter, the polymerization temperature was raised to 240 ° C., the pressure in the reactor was gradually reduced to 15 Torr,
After proceeding the polymerization for 1 hour, the temperature was further raised to 270 ° C., the pressure in the reactor was lowered to 0.5 Torr, and the polymerization was continued for 1 hour. After that, the pressure in the reactor was restored by nitrogen to recover about 200 g of the produced polymer, which was analyzed and evaluated according to the above-mentioned measurement method.

Examples 2 to 6, Comparative Examples 1 to 6 Cl content shown in Table 1 as diphenyl carbonate,
Table 1 shows the results of polymerization in the same manner as in Example 1 except that the total amount of N was used and the amount of Cs ₂ CO _{3 as} a catalyst was the amount shown in Table 1 with respect to 1 mol of bisphenol A.

[0047]

[Table 1]

[0048]

According to the present invention, it is possible to control the content of specific impurities contained in the diaryl carbonate to polymerize a polycarbonate having a good hue with a smaller amount of catalyst.

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Michio Kawai 1 Toho-cho, Yokkaichi-shi, Mie Mitsubishi Chemical Co., Ltd. Yokkaichi Plant (56) Reference JP-A-6-179744 (JP, A) JP-A-3- 47831 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C08G 64/00-64/42

Claims (7)

(57) [Claims] 1. A method for producing an aromatic polycarbonate by subjecting an aromatic dihydroxy compound and a diaryl carbonate to a melt polycondensation reaction in the presence of a transesterification catalyst to produce an aromatic polycarbonate, wherein the chlorine content of the readily water-soluble chlorine-based impurity is 30 pp.
b or less, and the total nitrogen content of nitrogen-containing impurities is 1.0
A method for producing an aromatic polycarbonate, which comprises using a diaryl carbonate having a content of ppm or less. 2. The method according to claim 1, wherein the total nitrogen content of the nitrogen-containing impurities contained in the diaryl carbonate is 0.7 ppm or less. 3. The method according to claim 1, wherein the total nitrogen content of the nitrogen-containing impurities contained in the diaryl carbonate is 0.5 ppm or less. 4. The method according to claim 1, wherein a basic compound is used as the transesterification catalyst. 5. The method according to claim 4, wherein the basic compound is at least one selected from alkali metals and alkaline earth metals. 6. The diaryl carbonate is obtained by reacting phosgene with a hydroxyaryl compound in the presence of a catalyst.
The method described in any one of. 7. The method according to claim 6, wherein the catalyst is a nitrogen-containing basic catalyst.