JPH07233247A - Production of aromatic polyester - Google Patents

Abstract

PURPOSE:To produce inexpensively and industrially an aromatic polyester of an excellent hue by directly melt-polymerizing an aromatic dicarboxylic acid with a specified diol component and a diaryl carbonate in the presence of a catalyst such as methylimidazole. CONSTITUTION:An aromatic dicarboxylic acid (A) is polycondensed by heating with a diol component (B) of formula I [wherein A2 and A3 are each phenylene; X is a group of formula II (wherein R<1> to R<4> are each H, halogen, 1-6C alkyl or the like; and q is 4-10)] and a diaryl carbonate (C) at about 280-400 deg.C in the presence of a catalyst which is an imidazole compound of formula III or IV (wherein R<5> is 1-6C alkyl, 5-10C cycloalkyl or the like; R<6> and R<7> are each H, halogen, 1-6C alkyl or the like; R<8> is H or 1-6C alkyl; and X<-> is a stable anion). The mixing ratio is such that the relationships: 1<=A/B<=1.1, and 0.8<=(A+B)/C<=1.2 are satisfied. The catalyst is used in an amount of desirably 0.05-0.8mol% based on component A, and its particularly desirable example is 1-methylimidazole or 1-butylimidazole. This polymer is amorphous and has an excellent hue.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing an aromatic polyester. More specifically, it relates to a method for producing an aromatic polyester having an excellent color tone from a dicarboxylic acid, a diol and a diarycarbonate.

[0002]

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

For example, polyarylates 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 are relatively balanced. It has excellent properties and is used for various purposes.

Various studies have hitherto been carried out on the production method of these amorphous aromatic polyesters, and among them, an interfacial polycondensation method between an acid halide of an aromatic dicarboxylic acid and an aromatic dihydroxy compound has been industrialized. There is. However, methylene chloride, which is usually used as a reaction solvent in this interfacial polycondensation method, is a chemical substance that has environmental and hygiene problems, and it must be handled with caution.
Since its boiling point is as low as 40 ° C., it is difficult and expensive to install a closed system in which methylene chloride used in the production of aromatic polyester can be completely recycled. Then, the melt polymerization method of these polymers is examined.

However, it is not practical to obtain these polymers directly by melt polymerization using a dicarboxylic acid and a diol, because the coloring is severe and the polymerization rate is low. Therefore, in practice, a method (1) using a diaryl ester of a dicarboxylic acid component and a diol in advance
Or a method (2) using a lower aliphatic carboxylic acid ester of a dicarboxylic acid and a diol, and 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 a high cost. Further, in the methods (2) and (3), since a lower aliphatic carboxylic acid is generated during the reaction, the apparatus is easily corroded, and the obtained polymer has a problem that the terminal COOH concentration is high.

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

However, in general, aromatic dicarboxylic acids have low solubility, and the rate of dissolution of the dicarboxylic acid component is limited.
Since the reaction must be carried out at a high temperature and requires a long time, there is a limit in improving the hue. Further, in the conventional melt polymerization method, sublimates are generated during the polymerization reaction, the process for removing them becomes complicated, and the equipment becomes large-scale,
As a result, there is a problem that the cost becomes high.

[0009]

SUMMARY OF THE INVENTION Therefore, the present invention provides a polyester having excellent heat resistance and mechanical properties as well as a hue, directly without diesterification of a dicarboxylic acid or a diol with a direct dicarboxylic acid and a diol or a diaryl. It is an object of the present invention to provide a method for industrially inexpensively producing a carbonate by a melt polymerization method.

[0010]

The present invention provides 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]

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]

[Chemical 8]

Represents

R ¹ , R ² , R ³ and R ⁴ are each independently 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 represents an integer of 4 to 10. In the production of an aromatic polyester, the diol component (b) represented by) is heated and melted in the presence of the diaryl carbonate (c) to produce an aromatic polyester, and the following formulas (III) and / or (IV)

[0016]

[Chemical 9]

[0017]

[Chemical 10]

(In the formulas (III) and (IV), R ⁵ has 1 carbon atom.
Are selected from an alkyl group having 6 to 6 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 are each independently 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 having 1 to 6 carbon atoms. X ⁻ is an anion that can exist stably. ), The intrinsic viscosity of 0.3 or more (phenol / 1, 1, 1,
2,2-Tetrachloroethane mixed solvent (weight ratio 60/4
0), and 35 ° C.).

The present invention will be described in detail below.

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.

Examples of the dicarboxylic acid component (a) represented by the above formula (I) include terephthalic acid, isophthalic acid, methylterephthalic acid, methylisophthalic acid, naphthalene-2,6-dicarboxylic acid, naphthalene-2,7- Dicarboxylic acid, diphenyl dicarboxylic acid, diphenyl ether dicarboxylic acid, diphenyl sulfone dicarboxylic acid,
Examples thereof include phenylindane dicarboxylic acid. These dicarboxylic acids may be used alone or in combination of two or more. Particularly, it is preferable to use terephthalic acid and isophthalic acid at the same time.

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 formula (II), A ² and A ³ are each a phenylene group which may be substituted. X is

[0025]

[Chemical 13]

R ¹ and R ² are each independently a hydrogen atom, a halogen atom such as chlorine and bromine, an alkyl group having 1 to 6 carbon atoms such as a methyl group, an ethyl group and a propyl group, a cyclopentyl group and a cyclohexyl group. Such as C5 or C6 cycloalkyl group, or C6 to C1 such as phenyl group
2 aryl or aralkyl groups. Or

[0027]

[Chemical 14]

A group which may have a substituent represented by
Indicates a chloroalkylidene group (R³, R ^FourEach independently water
Elemental atom, halogen atom, alkyl group having 1 to 6 carbon atoms, charcoal
Cycloalkyl group having a prime number of 5 or 6 and an alkyl group having a carbon number of 6 to 12
Selected from reel groups and aralkyl groups having 6 to 12 carbon atoms
It q represents an integer of 4 to 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) propyl
Lopan, 2- (4-hydroxyphenyl) -2- (3,
5-dichloro-4-hydroxyphenyl) propane, etc.
Of these, 2,2-bis (4-hydroxy)
Phenyl) propane, 1,1-bis (4-hydroxyphenyl)
Phenyl) cyclohexane is preferred. Also these geo
Two or more kinds may be used in combination.

Examples of the diaryl carbonate (c) used in the present invention include diphenyl carbonate, di-p-tolyl carbonate, dinaphthyl carbonate,
Di-p-chlorophenyl carbonate, phenyl-p-
Examples thereof include tolyl carbonate, and among these, diphenyl carbonate is particularly preferable. The diaryl carbonate may be substituted, may be used alone, or may be used in combination of two or more kinds.

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

[0031]

## EQU2 ## 0.1 ≦ A / B ≦ 1.1 (1) 0.8 ≦ (A + B) /C≦1.2 (2) (In the formula, A is the dicarboxylic acid component (a), B Is preferably used in a molar ratio such that the diol component (b) and C are each the number of moles of the diaryl carbonate (c). In the formula (1), when the ratio (A / B) of the dicarboxylic acid component and the diol component is close to 1, specifically 0.95 ≦ A / B ≦ 1.1, preferably 0.95 ≦ A When /B≦1.05, the polymer obtained is substantially the following formula (V):

[0032]

[Chemical 15]

[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 The aromatic polyester is composed of the repeating unit represented. When the dicarboxylic acid component is less than the diol component, specifically, 0.1 ≦ A / B <0.95, preferably 0.2 ≦ A / B <0.95, the obtained polymer is Repeating unit represented by the formula (V) and the following formula (VI)

[0034]

[Chemical 16]

(In the formula (VI), A ² , A ³ and X are represented by the formula (II)
Same as A ² , A ³ and X in the above. ), Which is an aromatic polyester consisting essentially of a repeating unit represented by the formula (1).

If this ratio (A / B) is less than 0.1, the heat resistance of the obtained polymer is deteriorated, which is not preferable. Further, when it is larger than 1.1, the dicarboxylic acid component is too much and the degree of polymerization does not increase, 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 ((A + B) / C) of the sum of the dicarboxylic acid component (a) and the diol component (b) to the diaryl carbonate (c). If this ratio is less than 0.8, the polymerization will be delayed, which is not preferable. On the other hand, if it is more than 1 or 2, coloring of the obtained polymer becomes severe, which is not preferable. In equation (2),
Preferably, 0.9 ≦ (A + B) /C≦1.15.

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

[0039]

[Chemical 17]

[0040]

[Chemical 18]

(R^FiveIs an alkyl group having 1 to 6 carbon atoms, charcoal
Cycloalkyl group having 5 to 10 primes and C 6 to 12 carbon atoms
Selected from reel groups and aralkyl groups having 6 to 12 carbon atoms
It R ⁶, R⁷Are each independently a hydrogen atom or halogen atom.
Child, C1-C6 alkyl group, C5-C10 shik
Low alkyl 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
It is an anion that can exist stably. ) Of the catalyst
Heat and melt the reaction in the presence. Compound represented by formula (III)
In the thing, R^FiveIs a methyl group, ethyl group, etc.
Cyclic groups such as kill group, cyclopentyl group, cyclohexyl group
Aryl such as alkyl group, phenyl group and naphthyl group
Groups and aralkyl groups such as benzyl group are preferred. R⁶, R⁷
Is a hydrogen atom, a halogen atom such as chlorine or bromine, or a methyl group.
Alkyl groups such as a vinyl group and an ethyl group are preferred. this house,
R⁶And R⁷Is more preferably a hydrogen atom,
In case of R^FiveIs more preferably an alkyl group as a substituent.
Is 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, 1, 5-dimethylimidazole,
Examples include 5-chloro-1-methylimidazole and 1,4,5-trimethylimidazole. Of these, 1-methylimidazole and 1-butylimidazole are particularly preferable.

Further, the compound represented by the above formula (IV) is
The organic acid salt or inorganic acid salt of the above formula (III), or the above formula (II)
It is a compound in which the imidazole ring of the compound represented by I) is quaternized. 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 or an alkyl group having 1 to 3 carbon atoms. X ⁻ is an anion that can exist stably, and examples thereof include acetate anion, benzoate anion, p-toluenesulfonate anion, chloride, bromide, sulfate ion, and 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 of hydrochloric acid, sulfuric acid, nitric acid and the like. Further, as the compound obtained by quaternizing the imidazole ring of the compound represented by the above formula (III), 1,3-dimethylimidazolium chloride, 1,3-dimethylimidazolium bromide, 1,3-dimethylimidazolium acetate, Examples thereof include 1-butyl-3-methylimidazolium bromide. Of these, organic acid salts are preferable, and benzoic acid salts are particularly preferable.

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

In this reaction, firstly the diaryl carbonate mainly reacts with the dicarboxylic acid component and the diol component to produce phenols. Generally, since aromatic dicarboxylic acids have low solubility, it requires a high temperature to start the initial reaction and a long time to complete the initial reaction. However, when the compounds represented by the above 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 each of () and (IV) is not particularly limited, but is preferably 0.01 mol% to 1 mol% with respect to the above component (a). If it is less than 0.01 mol%, the effect of the compound as a catalyst becomes insufficient. If it is more than 1 mol%, the physical properties of the obtained polymer may deteriorate. More preferably 0.05 mol% to 0.8 mol%
Is.

Further, the compounds represented by the above formulas (III) and (IV) may be used at the same time. In that case, the total amount used is 0.01 mol% to 1 with respect to the component (a).
The amount is preferably about mol%, 0.05 mol%
An amount of ~ 0.8 mol% is more preferred.

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

The polymerization temperature during the heat polycondensation is 280 to 4
It is necessary to set the temperature to 00 ° C. Here, the polymerization temperature means the temperature at the latter stage of polymerization or at the end thereof. When the polymerization temperature is lower than 280 ° C., the melt viscosity of the polymer becomes high, so that a polymer having a high degree of polymerization cannot be obtained, and when it is higher than 400 ° C., the polymer is apt to deteriorate, which is not preferable.

In the production method of the present invention, it is preferable that the polymerization reaction temperature is relatively low at the beginning and gradually raised to the above 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 reduced pressure. At atmospheric pressure, it is preferable to use an atmosphere of an inert gas such as nitrogen or argon. The polycondensation reaction time is not particularly limited, but is about 1 to 10 hours.

The aromatic polyester of the present invention obtained by the above-mentioned production method is 3% in a phenol / 1,1,2,2-tetrachloroethane mixed solvent (weight ratio 60/40).
It is necessary that the intrinsic viscosity measured at 5 ° C. be 0.3 or more. When the intrinsic viscosity is lower than 0.3, the heat resistance and toughness of the obtained polymer are insufficient, which is not preferable. Practically, the upper limit of 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. The fact that the polymer of the present invention is amorphous means that, for example, DS
It can be confirmed from the fact that the melting point cannot be obtained by C.

When producing the aromatic polyester of the present invention, various additives such as stabilizers, colorants, pigments and lubricants may be added, if desired.

[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 esterifying the dicarboxylic acid component or the diol component in advance and at a low cost. By such a melt polymerization process, it is possible to obtain a good color tone with almost no sublimate.

The aromatic polyester of the present invention has heat resistance,
It has a transparent property and is useful as a molded article such as a light rover for automobiles and electronic members.

[0055]

EXAMPLES The present invention will be described in detail below with reference to examples. In the examples, “parts” means “parts by weight”. The intrinsic viscosity was measured in a phenol / 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 by DSC at a temperature rising rate of 10 ° C./min.

[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
Part was put into 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 raised while gradually reducing the pressure in the system. After 6 hours from the start of the reaction, it was confirmed that the raw materials were uniformly dissolved when the temperature in the system was 300 ° C. and about 5 mmHg. After that, the temperature is further raised and the pressure is reduced to 32
It was 0 ° C. and 0.5 mmHg. Polymerization was carried out for 45 minutes under the same conditions to obtain a polymer. At this time, almost no sublimate was formed. The obtained polymer was light 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. 6 hours after the reaction started,
It was confirmed that the raw materials were uniformly dissolved when the temperature in the system was 300 ° C. and about 5 mmHg. After that, further heating,
The pressure was reduced to 320 ° C. and 0.5 mmHg in the system. Polymerization was performed for 60 minutes under the same conditions to obtain a polymer. At this time, almost no sublimate was formed. The obtained polymer was light yellow and transparent. The intrinsic viscosity was 0.59 and the glass transition temperature was 179 ° C.

Example 3 Furthermore, antimony trioxide 0.0
Example 1 was repeated except that 87 parts was added. After 6 hours from the start of the reaction, it was confirmed that the raw materials were uniformly dissolved when the temperature in the system was 300 ° C. and about 5 mmHg. After that, the temperature is further raised and the pressure is reduced, and the temperature in the system is 320 ° C. and 0.5 mm.
It was Hg. Polymerization was carried out for 45 minutes under the same conditions to obtain a polymer. At this time, almost no sublimate was formed. The obtained polymer was light 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 same procedure as in Example 1 was carried out except that parts were used. After 7 hours from the start of the reaction, it was confirmed that the raw materials were uniformly dissolved when the temperature in the system was set to 300 ° C. and about 5 mmHg. After that, the temperature is further raised and the pressure is reduced.
And Polymerization was performed for 60 minutes under the same conditions to obtain a polymer. At this time, almost no sublimate was formed. The obtained polymer was light 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, diphenyl carbonate 353.4 parts, 1-
Add 0.164 parts of methylimidazole to a reaction vessel having a vacuum distillation system equipped with a stirrer and a nitrogen inlet, and add 20
The reaction started at 0 ° C. After 30 minutes, raise the temperature to 220 ° C,
After 30 minutes at the same temperature, it was confirmed that the raw materials were uniformly dissolved when the system was set to about 400 mmHg. After that, the temperature is further raised and the pressure is reduced, and the temperature in the system is 300 ° C. and 0.5 mm.
It was Hg. Polymerization was performed for 60 minutes under the same conditions to obtain a polymer. At this time, almost no sublimate was formed. The obtained polymer was light yellow and transparent. 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. Even after 30 minutes at 220 ° C., there was no distillation of phenol, and the temperature was raised to 240 ° C. under normal pressure. After 30 minutes at the same temperature, the distillation of phenol was confirmed, and then the temperature in the system was gradually reduced while the temperature was further raised. 7 from the start of the reaction
After the lapse of time, it was confirmed that the raw materials were uniformly dissolved when the temperature in the system was 320 ° C. and about 5 mmHg. Thereafter, the temperature was further raised and the pressure was reduced to 320 ° C. and 0.5 mmHg in the system. Polymerization was performed for 60 minutes under the same conditions to obtain a polymer.
At this time, about 10 parts of sublimate was produced. The obtained polymer was light 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
There is no distillation of phenol even after a lapse of time, and at 240 ° C under normal pressure.
The temperature was raised to. After 30 minutes at the same temperature, the distillation of phenol was confirmed, and then the temperature in the system was gradually reduced while the temperature was further raised. 6 hours after 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 is further raised and the pressure is reduced to 320 ° C. in the system.
It was set to 0.5 mmHg. Polymerization was carried out for 45 minutes under the same conditions to obtain a polymer. At this time, about 12 parts of sublimate was produced. The obtained polymer was yellow and transparent. The intrinsic viscosity was 0.60 and the glass transition temperature was 177 ° C.

Claims (2)

[Claims] 1. A compound represented by the following formula (I): HOOC—A ¹ —COOH (I) (A ^{1 in the} above formula (I) is an aromatic group which may be substituted). The dicarboxylic acid component (a) and the following formula (II): HO—A ² —X—A ³ —OH (II) (A ² and A ³ in the formula (II) may be each substituted. It is a phenylene group, and X is Represents R ¹ , R ² , R ³ and R ⁴ are each independently 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 represents an integer of 4 to 10. In the case of producing an aromatic polyester by heating and melting a diol component (b) represented by) in the presence of a diaryl carbonate (c) to produce an aromatic polyester, the following formulas (III) and / or (IV) [Chemical 5] (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, and 6 to 6 carbon atoms.
It is selected from an aryl group having 12 and an aralkyl group having 6 to 12 carbon atoms. R ⁶ and R ⁷ are each independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms, or 5 to 10 carbon atoms.
Is a cycloalkyl group having 6 to 12 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 exist stably. ), The intrinsic viscosity of 0.3 or more (phenol / 1, 1, 1,
2,2-Tetrachloroethane mixed solvent (weight ratio 60/4
A method for producing an aromatic polyester having 0. 2. A dicarboxylic acid component (a), a diol component (b) and a diaryl carbonate (c) are represented by the following formulas (1) and (2): 0.1 ≦ A / B ≦ 1.1 ( 1) 0.8 ≦ (A + B) /C≦1.2 (2) (wherein A is a dicarboxylic acid component (a), B is a diol component (b), and C is each mole of a diaryl carbonate (c). The method for producing an aromatic polyester according to claim 1, characterized in that the above are used in a molar ratio satisfying at the same time.