JP3056628B2 - Method for producing aromatic polyester - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing an aromatic polyester. More specifically, the present invention relates to a method for producing an aromatic polyester having an excellent color tone from dicarboxylic acid, diol and diary carbonate.

[0002]

2. Description of the Related Art In recent years, performance requirements for engineering plastics having high heat resistance and excellent mechanical strength have been increasing. Amorphous engineering plastics include polyarylate, which is an aromatic polyester derived from aromatic diol and aromatic dicarboxylic acid, and aromatic polyester carbonate.

[0003] For example, polyarylate composed of 2,2-bis (4-hydroxyphenyl) propane (hereinafter abbreviated as bisphenol A) as an aromatic diol and terephthalic acid and isophthalic acid as an aromatic dicarboxylic acid is relatively balanced. It has excellent properties and is used for various purposes.

[0004] Various studies have been made on methods for producing these amorphous aromatic polyesters. Among them, an interfacial polycondensation method between an acid halide of an aromatic dicarboxylic acid and an aromatic dihydroxy compound has been industrialized. I have. However, methylene chloride, which is usually used as a reaction solvent in this interfacial polycondensation method, is a chemical substance having environmental and sanitary problems, and its handling requires great care.
Since its boiling point is as low as 40 ° C., it is difficult and expensive to obtain a closed system in which methylene chloride used in the production of the aromatic polyester can be completely recycled. Therefore, a melt polymerization method of these polymers is being studied.

[0005] However, it is not practical to obtain these polymers by direct melt polymerization using dicarboxylic acids and diols, because the coloring is severe and the polymerization rate is low. Therefore, actually, a method (1) in which a diaryl ester of a dicarboxylic acid component and a diol are used in advance.
Alternatively, a method (2) using a lower aliphatic carboxylic acid ester of a dicarboxylic acid and a diol, or a method of adding a lower aliphatic carboxylic acid anhydride when reacting with a dicarboxylic acid and a diol as an alternative to the method (2) ( 3) is used.

However, in the methods (1) and (2), the raw materials have to be esterified in advance, which causes an increase in cost. In the methods (2) and (3), the lower aliphatic carboxylic acid is generated during the reaction, so that the apparatus is easily corroded, and the obtained polymer has a problem that the terminal COOH concentration is large.

As a method for solving such a problem,
There is a method of reacting an aromatic dicarboxylic acid with an aromatic diol or diaryl carbonate. However, even with this method, it has been difficult to obtain an aromatic polyester or polyester carbonate having an excellent hue. As a method of improving hue, for example, Japanese Patent Publication No. 3-128926 discloses
A method for producing an aromatic polyester has been reported in which an aromatic dicarboxylic acid is reacted with an aromatic diol or diaryl carbonate using a borane-tertiary amine complex salt compound and / or a quaternary ammonium borohydride compound as a catalyst. Japanese Patent Application Laid-Open No. 4-236224 reports a method for producing an aromatic polyester using a specific tin compound as a catalyst.

However, aromatic dicarboxylic acids generally have low solubility and dissolution of the dicarboxylic acid component is rate-determining.
The reaction must be carried out at a high temperature and requires a long time, so that there is a limit to the improvement of the hue. In addition, in the conventional melt polymerization method, sublimates are generated during the polymerization reaction, the process becomes complicated for their removal, and the equipment becomes large,
As a result, there is a problem that the cost is increased.

[0009]

SUMMARY OF THE INVENTION Accordingly, the present invention provides a polyester which is excellent not only in heat resistance and mechanical properties but also in hue without directly esterifying a dicarboxylic acid or a diol without directly esterifying a dicarboxylic acid or a diol. It is an object of the present invention to provide an industrially inexpensive method for producing from carbonate by a melt polymerization method.

[0010]

According to the present invention, there is provided a compound represented by the following formula (I):

[0011]

Embedded image ^{HOOC-A 1 -COOH ... (I} ) (A 1 of the formula (I) is which may be substituted aromatic group.) A dicarboxylic acid component represented by (a) and the following formula ( II)

[0012]

Embedded image HO—A ² —X—A ³ —OH (II) (A ² and A ³ in the formula (II) are each a phenylene group which may be substituted. X is

[0013]

Embedded image

Represents the following.

R ¹ , R ² , R ³ and R ⁴ each independently represent a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms,
It is selected from a cycloalkyl group having 5 or 6 carbon atoms, an aryl group having 6 to 12 carbon atoms, and an aralkyl group having 6 to 12 carbon atoms. q shows the integer of 4-10. The diol component (b) represented by the following formula (III) and / or (IV) for producing an aromatic polyester by reacting the diol component (b) with the diol component (b) by heating and melting in the presence of a diaryl carbonate (c).

[0016]

Embedded image

[0017]

Embedded image

(In the formulas (III) and (IV), R ⁵ is a group having 1 carbon atom.
Or an alkyl group having 6 to 12 carbon atoms, a cycloalkyl group having 5 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, and an aralkyl group having 6 to 12 carbon atoms. R ⁶ and R ⁷ each independently represent a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms,
It is selected from a cycloalkyl group having 5 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, and an aralkyl group having 6 to 12 carbon atoms. R ⁸ is selected from a hydrogen atom and an alkyl group of 1 to 6 carbon waters. X ^- is an anion that can be stably present. ), Characterized in that the reaction is carried out in the presence of a catalyst represented by the formula:
2,2-tetrachloroethane mixed solvent (weight ratio 60/4)
0), 35 ° C.).

Hereinafter, the present invention will be described in detail.

The dicarboxylic acid component (a) used in the present invention is represented by the following formula (I).

[0021]

Embedded image ^{HOOC-A 1 -COOH ... (I} ) (A 1 of the formula (I) are substituted by an aromatic group.) The aromatic group in the formula (I), phenylene Group, a naphthylene group, or a group having a phenyl group or a naphthyl group.

The dicarboxylic acid component (a) represented by the above formula (I) includes, for example, terephthalic acid, isophthalic acid, methyl terephthalic acid, methyl isophthalic acid, naphthalene-2,6-dicarboxylic acid, naphthalene-2,7- Dicarboxylic acid, diphenyl dicarboxylic acid, diphenyl ether dicarboxylic acid, diphenyl sulfone dicarboxylic acid,
And phenylindanedicarboxylic acid. These dicarboxylic acids may be used alone or in combination. In particular, it is preferable to use terephthalic acid and isophthalic acid simultaneously.

The diol component (b) used in the present invention is represented by the following formula (II).

[0024]

Embedded image HO—A ² —X—A ³ —OH (II) In the above formula (II), A ² and A ³ are each a phenylene group which may be substituted. X is

[0025]

Embedded image

Wherein R ¹ and R ² are each independently a hydrogen atom, a halogen atom such as chlorine or bromine, an alkyl group having 1 to 6 carbon atoms such as a methyl group, an ethyl group or a propyl group, a cyclopentyl group or a cyclohexyl group. And C6 to C1 such as a cycloalkyl group having 5 or 6 carbon atoms or a phenyl group.
Selected from two aryl groups or aralkyl groups. Or

[0027]

Embedded image

And optionally substituted substituents represented by
Represents a chloroalkylidene group (R^Three, R ^FourAre each independently water
Element atom, halogen atom, alkyl group having 1 to 6 carbon atoms, charcoal
A cycloalkyl group having a prime number of 5 or 6;
Selected from reel groups and aralkyl groups having 6 to 12 carbon atoms
You. q shows the integer of 4-10. ) As such a diol component (b), 2,2-bis
(4-hydroxyphenyl) propane, 1,1-bis
(4-hydroxyphenyl) cyclohexane, 2,2-
Bis (3,5-dimethyl-4-hydroxyphenyl) p
Lopan, 2- (4-hydroxyphenyl) -2- (3,
5-dichloro-4-hydroxyphenyl) propane and the like
Illustrated are, among these, 2,2-bis (4-hydroxy
Phenyl) propane, 1,1-bis (4-hydroxyf
(Enyl) cyclohexane is preferred. In addition, these geo
Two or more kinds of metal components may be used in combination.

The diaryl carbonate (c) used in the present invention includes, for example, diphenyl carbonate, di-p-tolyl carbonate, dinaphthyl carbonate,
Di-p-chlorophenyl carbonate, phenyl-p-
Tolyl carbonate and the like can be mentioned, and among these, diphenyl carbonate is particularly preferred. The diaryl carbonate may be substituted, used alone or in combination of two or more.

In the present invention, the compound (a),
(B) and (c) are the following two relational expressions

[0031]

0.1 ≦ A / B ≦ 1.1 (1) 0.8 ≦ (A + B) /C≦1.2 (2) (where A is a dicarboxylic acid component (a), B Is a diol component (b), and C is the number of moles of the diaryl carbonate (c).). In the formula (1), when the ratio (A / B) of the dicarboxylic acid component to the diol component is close to 1, specifically, when 0.95 ≦ A / B ≦ 1.1, preferably 0.95 ≦ A When /B≦1.05, the obtained polymer is substantially the following formula (V)

[0032]

Embedded image

[0033] (In the formula (V), A ¹ is the same. In A ^2, A ^3, X of the same .A ^2, A ^3, X is in formula (II) to A ¹ in formula (I)) in It is an aromatic polyester composed of the repeating units represented. When the dicarboxylic acid component is less than the diol component, specifically when 0.1 ≦ A / B <0.95, preferably when 0.2 ≦ A / B <0.95, the obtained polymer is A repeating unit represented by the formula (V) and the following formula (VI)

[0034]

Embedded image

(In the formula (VI), A ² , A ³ and X represent the formula (II)
Same as A ² , A ³ and X in the table. ), Which is essentially an aromatic polyester carbonate comprising the repeating unit represented by the formula (1).

If the ratio (A / B) is less than 0.1, the heat resistance of the obtained polymer deteriorates, which is not preferable. On the other hand, if it is larger than 1.1, the degree of polymerization is not increased because the amount of the dicarboxylic acid component is too large, which is not preferable. In the formula (1), preferably, 0.2 ≦ A / B ≦ 1.05.

On the other hand, the formula (2) represents the molar ratio of the sum of the dicarboxylic acid component (a) and the diol component (b) to the diaryl carbonate (c) ((A + B) / C). If the ratio is less than 0.8, the polymerization is undesirably slow. On the other hand, if the ratio is larger than 1, the obtained polymer becomes too colored, which is not preferable. In equation (2),
Preferably, 0.9 ≦ (A + B) /C≦1.15.

In the method of the present invention, the compound (a)
(B) and (c) are represented by the following formulas (III) and / or (IV)

[0039]

Embedded image

[0040]

Embedded image

(R^FiveIs an alkyl group having 1 to 6 carbon atoms,
A cycloalkyl group having a prime number of 5 to 10;
Selected from reel groups and aralkyl groups having 6 to 12 carbon atoms
You. R ⁶, R⁷Are each independently a hydrogen atom or a halogen atom
, An alkyl group having 1 to 6 carbon atoms, a cycle having 5 to 10 carbon atoms
Loalkyl group, aryl group having 6 to 12 carbon atoms and carbon number
It is selected from 6 to 12 aralkyl groups. R⁸Is a hydrogen atom
And an alkyl group having 1 to 6 carbon atoms. X^-Is
An anion that can exist stably. ) Of the catalyst
A heat melting reaction is performed in the presence. Compound represented by formula (III)
In the object, R^FiveAre methyl groups, ethyl groups, etc.
Cycl, cyclopentyl, cyclohexyl, etc.
Aryl such as loalkyl, phenyl, naphthyl, etc.
And aralkyl groups such as benzyl. R⁶, R⁷
Hydrogen, chlorine, bromine and other halogen atoms, methyl
And alkyl groups such as ethyl group and ethyl group. this house,
R⁶And R⁷Is more preferably a hydrogen atom,
If R^FiveIs more preferably an alkyl group as a substituent.
Preferred.

Examples of the compound represented by the above formula (III) include 1-methylimidazole, 1-ethylimidazole, 1-butylimidazole, 1-cyclohexylimidazole, 1-phenylimidazole, 1,4-dimethylimidazole, 5-dimethylimidazole,
5-chloro-1-methylimidazole, 1,4,5-trimethylimidazole and the like. Of these, 1-methylimidazole and 1-butylimidazole are particularly preferred.

The compound represented by the above formula (IV) is
An organic acid salt or an inorganic acid salt of the above formula (III),
It is a compound obtained by quaternizing the imidazole ring of the compound represented by I). Here, R ⁸ in the above formula (IV) is selected from a hydrogen atom and an alkyl group having 1 to 6 carbon atoms, and is preferably a hydrogen atom and an alkyl group having 1 to 3 carbon atoms. X ^- is an anion that can be stably present, and examples thereof include an acetate anion, a benzoate anion, a p-toluenesulfonate anion, chloride, bromide, a sulfate ion, and a nitrate ion. Examples of such organic acid salts include salts of acetic acid, benzoic acid, p-toluenesulfonic acid and the like. Examples of the inorganic acid salt include salts such as hydrochloric acid, sulfuric acid, and nitric acid. Further, compounds obtained by quaternizing the imidazole ring of the compound represented by formula (III) include 1,3-dimethylimidazolium chloride, 1,3-dimethylimidazolium bromide, 1,3-dimethylimidazolium acetate, 1-butyl-3-methylimidazolium bromide and the like. Of these, organic acid salts are preferred, and benzoates are particularly preferred.

According to the present invention, by carrying out the reaction in the presence of the catalyst represented by the above formula (III) and / or (IV), the fragrance is excellent in color tone and the amount of sublimate generated during the reaction is small. A method for producing a group III polyester or polyester carbonate is provided.

In this reaction, first, a diaryl carbonate mainly reacts with a dicarboxylic acid component and a diol component to produce phenols. Generally, aromatic dicarboxylic acids have low solubility, so that high temperatures are required to initiate the initial reaction and long times are required to complete the initial reaction. However, when the compounds represented by the formulas (III) and (IV) are used, the initial generation of phenols is started at a very low temperature and in a short time. Therefore, it is considered that the time required for the reaction is shortened and the hue of the obtained polymer is significantly improved. The compound (III
The amount of (IV) and (IV) is not particularly limited, but is preferably 0.01 to 1 mol% with respect to the component (a). If the amount is less than 0.01 mol%, the effect of the compound as a catalyst becomes insufficient. If it is more than 1 mol%, the properties of the obtained polymer may be reduced. More preferably 0.05 mol% to 0.8 mol%
It is.

The compounds represented by the formulas (III) and (IV) may be used simultaneously. In this case, the total amount is from 0.01 mol% to 1 mol based on the component (a).
Mol%, preferably about 0.05 mol%
More preferred is an amount of .about.0.8 mol%.

Further, conventionally known transesterification catalysts other than the compounds represented by the above formulas (III) and (IV) may be used in combination. As these transesterification catalysts, for example, tin, antimony, strontium, zinc, cobalt, nickel, titanium, germanium, alkali metal,
Examples thereof include simple substances such as alkaline earth metals, oxides, hydroxides, halides, inorganic and organic acid salts, and complex salts.

The polymerization temperature during the heat polycondensation is from 280 to 4
It is necessary to be 00 ° C. Here, the polymerization temperature means a temperature at the end of the polymerization or at the end thereof. When the polymerization temperature is lower than 280 ° C., the polymer has a high melt viscosity, so that a polymer having a high degree of polymerization cannot be obtained. When the polymerization temperature is higher than 400 ° C., polymer deterioration or the like is liable to occur, which is not preferable.

In the production method of the present invention, it is preferable that the initial temperature of the polymerization reaction is relatively low, and that the temperature is gradually raised to finally reach the above-mentioned polymerization temperature. The reaction temperature of the initial polymerization reaction at this time is preferably 180 to 320 ° C. This polymerization reaction is carried out under normal pressure or under reduced pressure. At the time of normal pressure, it is preferable to be in an atmosphere of an inert gas such as nitrogen or argon. The polycondensation reaction time is not particularly limited, but is generally about 1 to 10 hours.

The aromatic polyester of the present invention obtained by the above-mentioned production method is mixed with a mixed solvent of phenol / 1,1,2,2-tetrachloroethane (weight ratio 60/40).
It is necessary that the intrinsic viscosity measured at 5 ° C. is 0.3 or more. If the intrinsic viscosity is lower than 0.3, the resulting polymer has insufficient heat resistance and toughness, which is not preferable. In practice, the upper limit of the viscosity is preferably about 2.

The aromatic polyester or polyester carbonate of the present invention obtained by the above-mentioned production method is an amorphous polymer, and a transparent molded article can be obtained by a melt molding method such as injection molding. Further, the fact that the polymer of the present invention is amorphous can be confirmed, for example, by DS
It can be confirmed from C that the melting point cannot be obtained.

In the production of the aromatic polyester of the present invention, various additives such as a stabilizer, a colorant, a pigment and a lubricant may be added as required.

[0053]

According to the production method of the present invention, an aromatic polyester having good heat resistance and mechanical properties can be produced directly from a dicarboxylic acid and a diol without previously esterifying a dicarboxylic acid component or a diol component. By a suitable melt polymerization process, it is possible to obtain a good color tone with almost no sublimation.

The aromatic polyester of the present invention has heat resistance,
It has transparency and is useful as a molded product such as light bars for automobiles and electronic members.

[0055]

The present invention will be described in detail with reference to the following Examples, in which "parts" means "parts by weight". The intrinsic viscosity was measured in a phenol / 1,1,1,2,2-tetrachloroethane mixed solvent (weight ratio 60/40) at a temperature of 35 ° C.
The thermal characteristics of the polymer were measured at a heating rate of 10 ° C./min using DSC.

Example 1 83.1 parts of terephthalic acid, 83.1 parts of isophthalic acid, 228.3 parts of 2,2-bis (4-hydroxyphenyl) propane, 428.4 parts of diphenyl carbonate, 1-methylimidazole 0.164
The reactor was placed in a reaction vessel having a vacuum distillation system equipped with a stirrer and a nitrogen inlet, and the reaction was started at 200 ° C. After 30 minutes, the temperature was raised to 220 ° C., and after 1 hour at the same temperature, the distillation of phenol was confirmed, and then the temperature was further increased while gradually reducing the pressure in the system. Six hours after the start of the reaction, it was confirmed that the raw materials were uniformly dissolved at a temperature of 300 ° C. and about 5 mmHg in the system. Thereafter, the temperature was further increased and the pressure was reduced, and
0 ° C. and 0.5 mmHg. Polymerization was carried out under the same conditions for 45 minutes to obtain a polymer. At this time, almost no sublimate was generated. The obtained polymer was pale yellow and transparent. The intrinsic viscosity was 0.50 and the glass transition temperature was 172 ° C.

Example 2 Example 1 was repeated except that 0.248 parts of 1-butylimidazole was used instead of 1-methylimidazole. Six hours after the start of the reaction,
It was confirmed that the raw material was uniformly dissolved at a temperature of 300 ° C. and about 5 mmHg in the system. After that, the temperature rises further,
The pressure was reduced to 320 ° C. and 0.5 mmHg in the system. Polymerization was carried out under the same conditions for 60 minutes to obtain a polymer. At this time, almost no sublimate was generated. The obtained polymer was pale yellow and transparent. The intrinsic viscosity was 0.59 and the glass transition temperature was 179 ° C.

Example 3 Further, antimony trioxide 0.0
The same procedure as in Example 1 was carried out except that 87 parts were added. Six hours after the start of the reaction, it was confirmed that the raw materials were uniformly dissolved at a temperature of 300 ° C. and about 5 mmHg in the system. Thereafter, the temperature was further increased and the pressure was reduced.
Hg. Polymerization was carried out under the same conditions for 45 minutes to obtain a polymer. At this time, almost no sublimate was generated. The obtained polymer was pale yellow and transparent. Intrinsic viscosity is 0.5
8. The glass transition temperature was 178 ° C.

Example 4 1-Butylimidazole benzoate 0.286 instead of 1-methylimidazole
The procedure was performed in the same manner as in Example 1 except that the parts were used. Seven hours after the start of the reaction, it was confirmed that the raw materials were uniformly dissolved at a temperature of 300 ° C. and about 5 mmHg in the system. Thereafter, the temperature was further increased and the pressure was reduced.
And Polymerization was carried out under the same conditions for 60 minutes to obtain a polymer. At this time, almost no sublimate was generated. The obtained polymer was pale yellow and transparent. The intrinsic viscosity was 0.55 and the glass transition temperature was 176 ° C.

Example 5 83.1 parts of terephthalic acid,
2,2-bis (4-hydroxyphenyl) propane 22
8.3 parts, 353.4 parts of diphenyl carbonate, 1-
0.164 parts of methylimidazole was placed in a reaction vessel having a vacuum distillation system equipped with a stirrer and a nitrogen inlet, and 20
The reaction was started at 0 ° C. After 30 minutes, the temperature was raised to 220 ° C,
After 30 minutes at the same temperature, it was confirmed that the raw material was uniformly dissolved at a pressure of about 400 mmHg in the system. Thereafter, the temperature was further increased and the pressure was reduced.
Hg. Polymerization was carried out under the same conditions for 60 minutes to obtain a polymer. At this time, almost no sublimate was generated. The obtained polymer was pale yellow and transparent. The intrinsic viscosity is 0.5
5. The glass transition temperature was 160 ° C.

Comparative Example 1 The procedure of Example 1 was repeated, except that 0.136 parts of imidazole was used instead of 1-methylimidazole. After 30 minutes at 220 ° C., no phenol was distilled off, and the temperature was raised to 240 ° C. at normal pressure. After 30 minutes at the same temperature, after confirming the distillation of phenol, the temperature was further increased while gradually reducing the pressure in the system. 7 from the start of the reaction
After a lapse of time, it was confirmed that the raw materials were uniformly dissolved at a temperature of 320 ° C. and about 5 mmHg in the system. Thereafter, the temperature was further increased and the pressure was reduced to 320 ° C. and 0.5 mmHg in the system. Polymerization was carried out under the same conditions for 60 minutes to obtain a polymer.
At this time, about 10 parts of the sublimate was generated. The obtained polymer was pale yellow and transparent. The intrinsic viscosity was 0.53 and the glass transition temperature was 173 ° C.

Comparative Example 2 The procedure of Example 1 was repeated except that 0.192 parts of 1,2-dimethylimidazole was used instead of 1-methylimidazole. 30 at 220 ° C
No phenol distills after minutes, 240 ° C at normal pressure
The temperature rose. After 30 minutes at the same temperature, after confirming the distillation of phenol, the temperature was further increased while gradually reducing the pressure in the system. After 6 hours from the start of the reaction, the temperature in the system is 320 ° C., about 5 mm
At Hg, it was confirmed that the raw materials were uniformly dissolved. After that, the temperature was further increased and the pressure was reduced,
0.5 mmHg was set. Polymerization was carried out under the same conditions for 45 minutes to obtain a polymer. At this time, about 12 parts of the sublimate was generated. The obtained polymer was yellow and transparent. The intrinsic viscosity was 0.60 and the glass transition temperature was 177 ° C.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-3-68626 (JP, A) JP-A-4-339823 (JP, A) JP-A-4-345616 (JP, A) (58) Field (Int. Cl. ⁷ , DB name) C08G 63/00-63/91 CA (STN) REGISTRY (STN)

Claims (2)

(57) [Claims] 1. A formula (I) ## STR1 ## ^{HOOC-A 1 -COOH ... (I} ) (A 1 of the formula (I) may be substituted is an aromatic group.) Represented by Dicarboxylic acid component (a) and the following formula (II): HO—A ² —X—A ³ —OH (II) (A ² and A ^{3 in} formula (II) may be substituted respectively. X is a phenylene group. Represents R ¹ , R ² , R ³ and R ⁴ each independently represent a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms,
It is selected from a cycloalkyl group having 5 or 6 carbon atoms, an aryl group having 6 to 12 carbon atoms, and an aralkyl group having 6 to 12 carbon atoms. q shows the integer of 4-10. The diol component (b) represented by the following formula (III) and / or (IV) for producing an aromatic polyester by subjecting the diol component (b) to a heat melting reaction in the presence of a diaryl carbonate (c): Embedded image (In the formulas (III) and (IV), R ⁵ is an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 5 to 10 carbon atoms,
It is selected from 12 aryl groups and aralkyl groups having 6 to 12 carbon atoms. R ⁶ and R ⁷ each independently represent a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms, 5 to 10 carbon atoms.
, An aryl group having 6 to 12 carbon atoms, a cycloalkyl group having 5 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, and an aralkyl group having 6 to 12 carbon atoms. R ⁸ is selected from a hydrogen atom and an alkyl group having 1 to 6 carbon atoms. X ^- is an anion that can be stably present. ), Characterized in that the reaction is carried out in the presence of a catalyst represented by the formula:
2,2-tetrachloroethane mixed solvent (weight ratio 60/4)
0), a method for producing an aromatic polyester having a temperature of 35 ° C). 2. The dicarboxylic acid component (a), the diol component (b) and the diaryl carbonate (c) are represented by the following formulas (1) and (2): 0.1 ≦ A / B ≦ 1.1 (1) 1) 0.8 ≦ (A + B) /C≦1.2 (2) (where A is a dicarboxylic acid component (a), B is a diol component (b), and C is a diaryl carbonate (c) mole) The method for producing an aromatic polyester according to claim 1, wherein the molar ratio is a number that simultaneously satisfies the following conditions.