JPH10245366A - High purity diaryl carbonate and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To clarify a chlorine source which most affects polymerization and a method for measuring the same in the production of an aromatic polycarbonate by a melt transesterification method using a diaryl carbonate, and to clarify an allowable amount thereof. Provide carbonate. SOLUTION: The chlorine content measured by the following measurement method is:
Diaryl carbonate having a content of 30 ppb or less. Chlorine measurement method: precisely weighed diaryl carbonate (5 g)
Is heated and dissolved in purified toluene (10 ml), ultrapure water (10 ml) is added, the mixture is stirred at room temperature for 10 minutes (magnetic stirrer at 1000 rpm), and chlorine in the aqueous phase is analyzed by ion chromatography.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a highly purified diaryl carbonate and a method for producing the same. The diaryl carbonate obtained in the present invention is useful as a raw material for producing an aromatic polycarbonate by a melt transesterification method.

[0002]

2. Description of the Related Art Polycarbonate is used for containers, optical disk substrates, optical lenses and the like. Chlorine having a low chlorine content is preferred because chlorine remaining in the polycarbonate reduces the hue of the polycarbonate, causes corrosion of a molding die, and leads to an error in reading information recording on an optical disk. JP-A-2-175722 discloses that a diaryl carbonate and an aromatic dioxy compound such as bisphenol A are subjected to melt polycondensation (ester exchange reaction) in the presence of a base method catalyst to obtain a chlorine content of 1 pp.
In producing polycarbonate having m (parts per million) or less, it is proposed to use diaryl carbonate and bisphenol A as raw materials having a low chlorine content.

Various methods for producing diaryl carbonate are known. For example, there are a method of phosgenating an aromatic monohydroxy compound in the presence of a quaternary ammonium salt catalyst, and a method of reacting an aqueous alkali metal solution of an aromatic monohydroxy compound with phosgene in the presence of an organic solvent. . Commercially produced diaryl carbonates contain various contaminants by any production method and require a purification step.
The contaminants include inorganic and organic chlorides, metal ions, iron compounds, reaction intermediates such as aryl chloroformates, organic solvents used in the production, and the like.

Japanese Patent Publication No. 38-1373 proposes a method for purifying a diaryl carbonate suitable for a transesterification method by treating a crude diaryl carbonate in a molten state with hot water or a hot weakly basic aqueous solution. However, when the example of this publication was additionally tested, the chlorine content was 0.6 p.
Only pm diphenyl carbonate was obtained. Other purification methods include a method of adding urea to diphenyl carbonate and melting by heating (Japanese Patent Publication No. 42-9820), a method of washing a molten diaryl carbonate with water and distilling it (JP-A-7-138208), and a method of crude diphenyl. A method of separating and crystallizing from a carbonate melt (JP-A-8-3119) and a method of distilling diphenyl carbonate in the presence of a basic substance (JP-A-8-198816)
No.) are known.

[0005] Of these contaminants, the presence of inorganic and organic chlorides is of particular importance because it has a significant effect on the polymerization rate and hue in the production of aromatic polycarbonates. However, as a commercially available high purity diaryl carbonate, only a diaryl carbonate on the order of 0.1 ppm can be obtained.

[0006] Japanese Patent Application Laid-Open No. Hei 4-100824 discloses that an aromatic dihydroxy compound is reacted with a diaryl carbonate to produce an aromatic polycarbonate.
Without using a polymerization catalyst, chlorine content is 0.05ppm
The following describes a method for producing an aromatic polycarbonate using a diaryl carbonate having a xanthone content of 10 ppm or less as a raw material. In this, chlorine means chlorine existing as an acid or salt such as hydrochloric acid, sodium chloride, potassium chloride, or chlorine in an organic compound such as phenylchloroformate.
It is described that it can be quantified by measuring chloride ion by potentiometric titration using a NO ₃ solution.

[0007] According to the above-mentioned JP-A-7-138208.
If the chloride concentration in the crude diaryl carbonate
(6.6 to 7.0 ppm), wash 1 to 3 times
Or the reuse of water,
-Titable chloride in carbonate reduced to 1 ppm
It has been done. According to the above-mentioned JP-A-8-198816.
If so, ordinary commercially available diphenyl carbonate
About 1 to 10 ppm chlorine is contained as decomposable chlorine.
Add a basic substance to this diphenyl carbonate
By distillation, the hydrolyzable chlorine is 0.1 to 0.1.
It is 4 ppm. Among them, hydrolysable chlorine is
Diphenyl carbonate dissolved or melted
Means chlorine that can be extracted with water, specifically sodium chloride
Salts such as um, and water content such as phenylchloroformate
Refers to chlorine derived from solvable compounds.
Is precisely weighed about 5 g of diphenyl carbonate, and toluene
Add 10 ml, dissolve in a 60 ° C water bath,
Extract (2.8 mM NaHCO_Three/2.25 mM
Na_TwoCO _ThreeNaBr was added to the above solution as an internal standard.
Add 10 ml and do not heat in a 60 ° C water bath.
Stir with magnetic stirrer for 6 hours and leave to cool
Later, the aqueous phase was analyzed by ion chromatography.
It is going to be measured more.

As described above, various methods have been proposed for reducing and measuring trace amounts of chlorine, but optical disk substrates, ICs, and lasers that require higher precision information are required.
For the use of transport containers such as ED wafers, a diaryl carbonate with a lower chlorine content is required to prevent malfunction of these precision components, and the effects of hue and malfunction due to the type of chlorine are expected to be clarified. Had been.
The description of the conventional chlorine content indicates hydrolyzable chlorine, that is, chlorine existing as an acid or salt such as hydrochloric acid, sodium chloride, or potassium chloride, or chlorine in an organic compound such as arylchloroformate. there were. Naturally, it was thought that the influence of these chlorines on the production of the aromatic polycarbonate was different depending on the form, but no detailed study was made.

[0009]

SUMMARY OF THE INVENTION The present inventors have found that, out of various chlorines, only active chlorine which is easily extracted into water has the greatest effect on the polymerization rate of an aromatic polycarbonate. The present invention has been completed. From the mechanism of influence on the polymerization rate, hydrochloric acid is considered as the main active chlorine. In the case of hydrochloric acid, it is presumed that a strong complex or salt is immediately formed with the polymerization catalyst or the like, thereby inhibiting the prompt progress of polymerization. Known chlorine determination methods include active chlorine, which is easily extracted into water, as well as chlorine liberated by the hydrolysis of organic compounds such as arylchloroformates. It is premised that hydrolysis takes place in order to give, and when compared at the same concentration, it has been found that the effect on the actual polymerization process is smaller than active chlorine which can be easily extracted into water. The present invention clarifies the chlorine source that most affects the polycarbonate and the method of measuring the same for the diaryl carbonate used for the production of the aromatic polycarbonate by the melt transesterification method using the diaryl carbonate, and clarifies the allowable amount of the diaryl carbonate. The purpose is to provide carbonate.

[0010]

SUMMARY OF THE INVENTION The present invention provides a diaryl carbonate having a chlorine content of 30 ppb or less as measured by the following measuring method. Chlorine measurement method: 5 g of diaryl carbonate is added to 10 ml of toluene, dissolved at 60 ° C., 10 ml of ultrapure water is added, and the mixture is stirred at room temperature (20 to 30 ° C.) for 10 minutes. Then, chlorine in the aqueous phase is subjected to ion chromatography. analyse.

Such a diaryl carbonate is obtained by reacting an aromatic monohydroxy compound with phosgene or an aryl chloroformate in the presence of an aromatic heterocyclic nitrogen-containing basic compound to form a reaction mixture of 80 to 80%.
After neutralization by contacting with an aqueous alkali solution at 95 ° C., the organic phase is separated into an aqueous phase and the organic phase is brought into contact with warm water at 80 to 95 ° C., again separated into an aqueous phase and an organic phase. It is obtained by recovering diaryl carbonate from the organic phase by distillation.

[0012]

In the production of the aromatic polycarbonate by the melt transesterification method, the chlorine content in the reaction solution was obtained by purifying the chlorine content to 10,000 to 1 / 200,000. By using a diaryl carbonate having a chlorine content of 30 ppb or less as measured by the above measurement method, the amount of polymerization catalyst added can be reduced as compared with the case of using a diaryl carbonate according to a conventional method. The amount of polymerization catalyst remaining in the aromatic polycarbonate is reduced,
An aromatic polycarbonate having better color tone and physical properties than conventional products can be obtained.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Aromatic monohydroxy compound: An aromatic monohydroxy compound is a compound in which a hydroxy group is directly bonded to an aromatic ring, such as alkylphenols such as phenol, cresol and butylphenol, arylphenols, Halogenated phenols and phenols having an alkyl or aryl group bonded through a heteroatom can be used.

Aryl chloroformate: As the aryl chloroformate, the above-mentioned aromatic monohydroxy compound chloroformate can be used. Phosgene: As phosgene, pure phosgene containing no impurities such as methylene chloride and carbon tetrachloride is preferable. Phosgene is used in an amount of 1.0 mol or less, preferably 0.4 to 0.5 mol, per 1.0 mol of the aromatic monohydroxy compound.

An aromatic heterocyclic nitrogen-containing basic compound or
Salts: As the aromatic heterocyclic nitrogen-containing basic compound used as a catalyst, a nitrogen atom is present in an aromatic 5- or 6-membered ring, and phosgene or a carbonate ester under the reaction conditions. Is a basic nitrogen compound that does not have a functional group (for example, an amino group or a hydroxy group) that is liable to form a strong bond with the ring. May be. Specific examples of such catalysts are pyridine, quinoline, picoline, imidazoles, benzimidazoles, pyrazoles, triazoles and benzotriazoles.

The aromatic heterocyclic nitrogen-containing basic compound catalyst is immediately converted to the corresponding hydrochloride in the reaction mixture.
Since this hydrochloride is in a dissociation equilibrium state with the free basic catalyst, instead of the free basic catalyst, a salt of the basic catalyst, for example, an inorganic acid salt such as hydrochloride or sulfate, or a formate is used. Organic salts such as acetic acid and salts can be used. These catalysts are preferably used in an amount of 0.001 to 0.20 mol, more preferably 0.01 to 0.10 mol, per 1.0 mol of the aromatic monohydroxy compound.

Alkali: As the alkali, hydroxides of sodium, potassium, calcium and barium, and sodium and ammonium salts of carbonic acid and phosphoric acid can be used. Reaction: One example of obtaining a high-purity diaryl carbonate of the present invention will be described with reference to FIG. A mixture of the aromatic monohydroxy compound 1 and the aromatic heterocyclic nitrogen-containing basic compound or its salt 2 is charged into the reactor 4,
The temperature is raised to 190 ° C., the mixture is melted, and the reaction is carried out by introducing gaseous phosgene 3 into the mixture at the same temperature with sufficient stirring.

The amount of phosgene introduced is preferably 1.0 mol or less, more preferably 0.4 to 0.5 mol, per 1.0 mol of the aromatic monohydroxy compound. Although the stoichiometric amount is 0.5 mol, the unreacted aromatic monohydroxy compound inevitably remains by suppressing the amount of phosgene to be introduced below the stoichiometric amount, and is a reaction intermediate. The reaction of forming a diaryl carbonate between the aryl chloroformate and the aromatic monohydroxy compound is accelerated, and a reaction mixture containing almost no aryl chloroformate which has a bad influence on the production of an industrial grade colorless polycarbonate can be obtained. At this time, if necessary, nitrogen gas 5 is blown into the reaction mixture after the introduction of phosgene, and hydrochloric acid 6 generated by the reaction is removed to the outside of the system, whereby the equilibrium reaction between the arylchloroformate and the aromatic monohydroxy compound is further increased. Can be promoted.

The mixture after completion of the reaction contains diaryl carbonate, unreacted aromatic monohydroxy compound, trace impurities, and a hydrochloride of an aromatic heterocyclic nitrogen-containing basic compound as a catalyst. The content will be about 300 to 60,000 ppm depending on the amount of catalyst used. To remove chlorine, the reaction mixture 7 taken out of the reactor 4
Neutralize by contacting with an aqueous alkali solution 8 at 0 to 95 ° C .;
The neutralized solution of H7-13 is separated into an organic phase and an aqueous phase in a separation tank 9, and the organic phase is extracted and brought into contact with hot water 10 at 80-95 ° C. This is done by separating into the aqueous phase.

In order to easily and efficiently recover the basic catalyst, the aqueous phase and the separated organic phase are led to a distillation column, where the free basic catalyst 12 and the unreacted aromatic monohydroxy compound 13 are separated by distillation. Diaryl carbonate 14
To separate. The distillation temperature is 50 to 80 ° C. at 20 to 40 torr when the free basic catalyst is pyridine, and 50 to 100 ° C. at 20 to 40 torr when the unreacted aromatic monohydroxy compound is phenol. 5-10t for diphenyl carbonate, etc.
140-160 ° C in orr. The production of the diaryl carbonate of the present invention may be of a continuous type or a batch type (batch type).

[0021]

The present invention will be described below in more detail with reference to examples. Example 1 A jacketed glass reaction vessel connected to an oil circulation type external heating device (internal volume: 1 liter,
(An overflow tube was installed at a position of 0 ml). An exhaust pipe with a condenser for removing generated hydrochloric acid gas to the outside of the system was connected to the second and third reaction vessels. The molten phenol, which was previously added with 5 mol% of pyridine and stirred, was heated to 150 ° C. while continuously supplying the molten phenol to the first reaction vessel at about 700 ml / hr (phenol 716 g / hr, corresponding to pyridine 30 g / hr). Warmed.
With sufficient stirring, the feed phenol was added at 0.1%.
48 moles of phosgene (361 g / hr) were continuously fed to the first reaction vessel.

The reaction mixture flowing out of the first reaction vessel is
The reaction mixture was supplied to the second reactor via an overflow pipe, and the reaction mixture flowing out of 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.

After the composition was sufficiently stabilized, 1 kg of the reaction mixture (composition: 89% by weight of diphenyl carbonate, 6% by weight of phenol, 5% by weight of pyridine hydrochloride, phenyl chloroformate not detected) was taken out of the oil circulation system. It was placed in a jacketed glass reaction vessel connected to a heating device and heated to 85 ° C. 372 g of a 5% by weight aqueous sodium hydroxide solution heated to 85 ° C.
Was added, and the mixture was stirred for 5 minutes, allowed to stand for 30 minutes, and then the aqueous phase and the organic phase were separately extracted. The pH after the addition of the aqueous sodium hydroxide solution was 9. The extracted organic phase is again
It was placed in a jacketed glass reaction vessel connected to an oil circulation type external heating device and heated to 85 ° C. 8
300 g of demineralized water heated to 5 ° C. was added, stirred for 5 minutes, allowed to stand for 5 minutes, and then the aqueous phase and the organic phase were separately extracted.

Sulzer packing (Sumitomo Heavy Industries) 1
The separated organic phase was purified by distillation in a vacuum distillation column packed with zero pieces. Specifically, at a vacuum degree of 20 to 40 torr, an oil bath temperature of about 220 ° C. and a top temperature of 50 to 80 ° C., free pyridine and phenol are distilled off,
Torr, oil bath temperature about 230 ° C, top temperature 15
At 0 ° C., 750 g of purified diphenyl carbonate containing no free pyridine and no aryl chloroformate (0 ppm) were obtained.

5 g of this diphenyl carbonate is added to 10 ml of toluene and dissolved at 60 ° C., then 10 ml of ultrapure water (ion-exchanged water containing no Cl) is added, and the mixture is stirred at 1000 rpm using a magnetic stirrer in a constant temperature room at 23 ° C.
After stirring for minutes, the chlorine in the aqueous phase was analyzed by ion chromatography and found to be 20 ppb. Incidentally, the chlorine content of the same diphenyl carbonate was determined according to
It was 50 ppb when measured by the hydrolyzable chlorine measurement method described in JP-A-8816.

Application Example 1 183 g (0.800 mol) of bisphenol A (manufactured by Nippon Steel Chemical Co., Ltd.) and cesium carbonate 2 were placed in a 500 ml glass separable flask equipped with an electropolished stirring blade.
0.5 of 60 μg (1 μmol / mol of bisphenol A)
% Aqueous solution, diphenyl carbonate 18 obtained in Example 1
8 g (0.880 mol) and added under nitrogen atmosphere.
Stirred at 100 ° C. for 100 minutes. Next, 100 torr at 210 ° C
and the mixture was stirred for 60 minutes.

Further, the pressure was reduced to 15 torr at 240.degree.
Stirred for 0 minutes. Next, the pressure was reduced to 1 torr or less at 270 ° C., followed by stirring for 60 minutes. The obtained polycarbonate was taken out, and the molecular weight and the color tone were evaluated by the following methods. Molecular weight: The average molecular weight is calculated from the viscosity of the methylene chloride solution. Color: Measure the Yl value of the methylene chloride solution. Table 1 shows the results. An IC chip is placed in an IC chip transfer tray obtained by injection molding this polycarbonate, and
No malfunction was found for the electrical products that had been stored for months and in which the IC chip was incorporated.

Example 2 Diphenyl carbonate having a chlorine content of 10 ppb was obtained in the same manner as in Example 1 except that the step of washing and separation with demineralized water at 85 ° C. was repeated twice (Japanese Unexamined Patent Publication No.
The measured value by the hydrolyzable chlorine measurement method described in 198816 was 15 ppb. Application Example 1)
The polymerization was evaluated with the catalyst amount of as half. Since the amount of active chlorine was reduced, there was no problem in polymerization even if the amount of catalyst was reduced, and a product having a good color tone was obtained.

Example 3 The chlorine content by the measurement method of the present invention was 20 ppb,
The same polymerization evaluation as in Application Example 1 was performed using diphenyl carbonate having a chlorine content of 90 ppb according to the hydrolyzable chlorine measurement method described in JP-A-8-198816. Active chlorine (20 ppb) by the analysis method of the present invention
If the amount of chlorine other than the above is 70 ppb (a value obtained by subtracting the chlorine content according to the measuring method described in claims from the chlorine content according to the hydrolyzing chlorine measuring method described in JP-A-8-198816), the polymerization is adversely affected. Did not. Table 1 shows the results. There was no malfunction of the IC chips stored in the IC chip transport tray injection-molded in the same manner as in Application Example 1.

COMPARATIVE EXAMPLE 1 A chlorine content of 110 ppb according to the method described in the claims.
The same polymerization evaluation as in Application Example 1 was carried out using diphenyl carbonate (the measured value of the hydrolyzable chlorine measurement method described in JP-A-8-198816 was 150 ppb).
Since the polymerization catalyst was poisoned by active chlorine, it hardly polymerized. Table 1 shows the results.

Comparative Example 2 The same polymerization evaluation as in Comparative Example 1 was carried out except that the amount of the catalyst during the polymerization was doubled. Polymerization proceeded due to the addition of a catalyst in an amount equal to or greater than the amount of the catalyst poisoned by the contained active chlorine, but the color tone was poor, probably due to an increase in the amount of metal mixed from the catalyst. Table 1 shows the results.

[0032]

[Table 1] *: Chlorine content according to the chlorine measurement method described in the present invention. **: Chlorine content according to the hydrolyzable chlorine measurement method described in JP-A-8-198816. ***: μmol / Bisphenol A mol

[0033]

According to the present invention, in the production of an aromatic polycarbonate by a melt transesterification method using the high-purity diaryl carbonate of the present invention, the amount of polymerization catalyst to be added can be reduced. The amount of the catalyst is reduced, and an aromatic polycarbonate having better color tone and physical properties than the conventional one can be obtained.

[Brief description of the drawings]

FIG. 1 is a flow sheet diagram showing a method for producing a diaryl carbonate of the present invention.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Michio Kawai 1 Tohocho, Yokkaichi City, Mie Prefecture Inside Yokkaichi Research Institute, Mitsubishi Chemical Corporation

Claims (2)

[Claims] 1. The chlorine content measured by the following measurement method,
Diaryl carbonate having a content of 30 ppb or less. Chlorine measurement method: 5 g of diaryl carbonate is added to 10 ml of toluene, dissolved at 60 ° C., 10 ml of ultrapure water is added, and the mixture is stirred at room temperature (20 to 30 ° C.) for 10 minutes. Then, chlorine in the aqueous phase is subjected to ion chromatography. analyse. 2. A reaction mixture formed by reacting an aromatic monohydroxy compound with phosgene or an arylchloroformate in the presence of an aromatic heterocyclic nitrogen-containing basic compound, and reacting with an aqueous alkaline solution at 80 to 95 ° C. After contacting and neutralizing, the mixture is separated into an organic phase and an aqueous phase.
It is brought into contact with hot water of 95 ° C., again separated into an aqueous phase and an organic phase,
The method for producing a diaryl carbonate having a chlorine content of 30 ppb or less according to claim 1, wherein the diaryl carbonate is recovered from the separated organic phase by distillation.