JPH0759629B2 - Method for producing wholly aromatic polyester - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a wholly aromatic polyester having excellent strength, rigidity and heat resistance, which is used for mechanical parts, electric / electronic parts, fibers and the like.

[Conventional technology]

As an established production method for producing wholly aromatic polyester, acetylation of a hydroxyl group or a carboxyl group of an aromatic diol, an aromatic dicarboxylic acid or an aromatic hydroxycarboxylic acid with an acetylating agent or a phenyl esterifying agent is performed. Alternatively, a method of producing a polymer by a deacetic acid reaction or a dephenol reaction using a monomer obtained by phenyl esterification is known (Japanese Patent Publication No. 47-47).
870). However, this method has a problem that the cost is high because an acetylated or phenyl esterified monomer is used.

In order to solve the above problems, as a method for producing a wholly aromatic polyester by a direct polycondensation reaction from an aromatic diol and an aromatic dicarboxylic acid, antimony oxide, titanium,
A method for producing a high molecular weight aromatic polyester by a direct polycondensation reaction of an aromatic diol and an aromatic dicarboxylic acid in the presence of a catalyst such as a tin compound is known (Japanese Patent Publication No.
61-20566). However, aromatic hydroxycarboxylic acids cannot be used in this method. This is because the decarboxylation reaction (for example, hydroxybenzoic acid becomes carbon dioxide with phenol) proceeds during the intended direct esterification of an aromatic hydroxycarboxylic acid, and the yield of the polymer decreases. .

Further, a high molecular weight polyester is produced by a direct polycondensation reaction of an aromatic hydroxycarboxylic acid, an aromatic diol and an aromatic dicarboxylic acid in the presence of a catalytic amount of a metal compound selected from a metal IV or a metal V. A method is known (JP-A-58-179223). In this way,
As aromatic hydroxycarboxylic acid, p-hydroxybenzoic acid and hydroxynaphthoic acid are used. Hydroxynaphthoic acid does not undergo a decarboxylation reaction, but p-hydroxybenzoic acid undergoes a marked decarboxylation reaction, and p-hydroxybenzoic acid in the produced polymer
-The proportion of hydroxybenzoic acid is reduced, with which the yield of polymer is reduced.

Therefore, it has not yet been known to suppress the decarboxylation reaction of aromatic hydroxycarboxylic acid, particularly p-hydroxybenzoic acid, in direct polycondensation.

[Problems to be Solved by the Invention]

The present invention has been made based on the above circumstances, and an object thereof is to suppress the decarboxylation reaction of an aromatic hydroxycarboxylic acid in a direct polycondensation system, thereby producing an aromatic hydroxycarboxylic acid or an aromatic hydroxycarboxylic acid. It is an object of the present invention to provide a method for obtaining a high-strength polyester in high yield by using a diol and an aromatic dicarboxylic acid as raw materials.

[Means for Solving the Problems]

MEANS TO SOLVE THE PROBLEM As a result of investigating the method of making an aromatic hydroxycarboxylic acid, an aromatic diol, and an aromatic dicarboxylic acid react by a direct polycondensation method, as a result of investigating in order to solve the said subject, reaction sequence, reaction It was found that the decarboxylation reaction of aromatic hydroxycarboxylic acid can be suppressed by devising the method, and the present invention has been completed based on this finding.

That is, the present invention is a method for producing a wholly aromatic polyester by reacting an aromatic hydroxycarboxylic acid, an aromatic diol, and an aromatic dicarboxylic acid, wherein an aromatic diol or an aromatic diol and an aromatic hydroxycarboxylic acid are used.
It was obtained by acylating with an acid anhydride represented by R ¹ -CO-O-CO-R ¹ (wherein R ¹ is an alkyl group having 1 to 10 carbon atoms), and then reacting with an aromatic hydroxycarboxylic acid. Provided is a method for producing a wholly aromatic polyester, which comprises polycondensing a reaction product and an aromatic dicarboxylic acid.

According to the method of the present invention, as shown in the following formula, an aromatic hydroxycarboxylic acid is obtained by reacting an aromatic diol or an acylated product of an aromatic diol and an aromatic hydroxycarboxylic acid with an aromatic hydroxycarboxylic acid. By synthesizing the oligomer [I] having a protected carboxyl group and directly polycondensing this with an aromatic dicarboxylic acid, the decarboxylation reaction of the aromatic hydroxycarboxylic acid is significantly reduced, and as a result, the yield is improved. Furthermore, a polymer having good physical properties (thermal properties, mechanical properties) can be obtained.

(1) Step of forming oligomer of terminal group [-OH] HO-Ar ₁ -OH + 2R ¹ CO-O-COR ¹ → R ¹ CO-O-Ar ₁ -O-COR ¹ + 2R ¹ COOH HOOC-Ar ₂ -OH + R ¹ CO-O-COR ¹ → HOOC-Ar ₂ -O-COR ¹ + R ¹ COOH R ¹ CO-O-Ar ₁ -O-COR ¹ +2 HOOC-Ar ₂ -OH → HO-Ar ₂ -CO-O-Ar _{1 -O-CO-Ar 2 -OH +} 2R 1 COOH R 1 CO-O-Ar 1 -O-COR 1 + R 1 CO-O-Ar 2 -COOH + HO-Ar 2 -COOH → HO-Ar 2 -CO p O- _{Ar 1 -OCO-Ar 2 -O q} H
[I] + (p + q) R ¹ COOH (2) Direct polycondensation step (In the formula, Ar ₁ , Ar ₂ and Ar ₃ represent a divalent group having an aromatic ring, p and q each independently represent an integer of 0 to 10, and p and q are 0 at the same time. , S and t represent the degree of polymerization.) As an aromatic diol represented by the formula HO—Ar ₁ —OH (Ar ₁ represents a divalent group having an aromatic ring), a formula usually used (In the formula, X is —O— or —SO ₂ —, m is 0 or 1, and n is 0 or 1) and various compounds are used. Specifically, for example, 4,4'-dihydroxydiphenyl, 4,4'-dihydroxydiphenyl ether, 4,4'-dihydroxydiphenyl sulfone, 4,
4'-dihydroxydiphenyl ketone, bisphenol A, phenolphthalein, hydroquinone, resorcinol, methylhydroquinone, chlorohydroquinone, phenylhydroquinone, phenoxyhydroquinone, t-butylhydroquinone, phenylethylhydroquinone, 2,6-dihydroxynaphthalene, 1,4- Dihydroxynaphthalene, 1,5-dihydroxynaphthalene, 2,6
-Dihydroxyanthraquinone, 1,4-dihydroxyanthraquinone, 1,5-dihydroxyanthraquinone, imide ring precursors (A) and (B) represented by the following formula: (The hydroxyl group is located at the 4 or 5 position on the benzene ring with respect to the amide group.) (The hydroxyl group is located at the p-position or the m-position with respect to the amide group.) 2,5-Frangimethylol, 2,6-pyridinedimethylol, N- (4-hydroxyphenyl) hydroxyphthalimide, N- (3 -Hydroxyphenyl) hydroxyphthalimide and the like. Among these, preferably,
4,4'-dihydroxydiphenyl, hydroquinone, 2,6
-Dihydroxynaphthalene, 2,6-dihydroxyanthraquinone, imide ring precursor A and imide ring precursor B, and particularly preferably 4,4'-dihydroxydiphenyl.

You may use these in mixture of 2 or more types.

Specific examples of the aromatic hydroxycarboxylic acid represented by the formula HO—Ar ₂ —COOH (Ar ₂ represents a divalent group having an aromatic ring) include the following compounds.

p-hydroxybenzoic acid, m-hydroxybenzoic acid, 3
-Methoxy-4-hydroxybenzoic acid, 3,5-dimethoxy-4-hydroxybenzoic acid, 3-methyl-4-hydroxybenzoic acid, 3,5-dimethyl-4-hydroxybenzoic acid, 2,6-dimethyl-4 -Hydroxybenzoic acid, 3-chloro-4-hydroxybenzoic acid, 2-chloro-4-hydroxybenzoic acid, 2,3-dichloro-4-hydroxybenzoic acid, 3,5-dichloro-4-hydroxybenzoic acid, 2 , 5-
Dichloro-4-hydroxybenzoic acid, 3-bromo-4-
Hydroxybenzoic acid, 3-phenyl-4-hydroxybenzoic acid, 2-phenyl-4-hydroxybenzoic acid, 3-
Phenoxy-4-hydroxybenzoic acid, 6-hydroxy-2-naphthoic acid, 6-hydroxy-5-chloro-2-
Naphthoic acid, 6-hydroxy-5-methyl-2-naphthoic acid, 7-hydroxy-5-methoxy-2-naphthoic acid, 6-hydroxy-7-chloro-2-naphthoic acid, 4
Imido ring precursors such as -carboxy-4'-hydroxybiphenyl, (5-carboxyphthal) 3 or 4-hydroxyanilide or (4-carboxyphthal) 3 or 4-hydroxyanilide, N- (4-hydroxyphenyl) There are trimellitimide, N- (3-hydroxyphenyl) trimellitimide, N- (4-carboxyphenyl) hydroxyphthalimide and N- (3-carboxyphenyl) hydroxyphthalimide, preferably p-hydroxybenzoic acid, 6- Hydroxy-2-naphthoic acid, which is the imide ring precursor. Particularly preferably, p
-Hydroxybenzoic acid.

You may use these in mixture of 2 or more types.

Examples of the acid anhydride represented by the formula R ¹ -CO-O-CO-R ¹ include:
Examples thereof include acetic anhydride, propionic anhydride, butyric anhydride, and isobutyric anhydride, and acetic anhydride is preferably used.

The acylation reaction with the acid anhydride is performed on the aromatic diol, but may be performed in the presence of the aromatic hydroxycarboxylic acid. In this case, the acid anhydride is used in an equimolar amount or more with respect to the hydroxyl group of the aromatic diol and the hydroxyl group of the aromatic hydroxycarboxylic acid. If it is less than equimolar, hydroxyl groups that are not acylated are generated. The reaction is preferably carried out using equimolar acid anhydride.

The aromatic diol and the aromatic hydroxycarboxylic acid are represented by [aromatic diol]: [aromatic hydroxycarboxylic acid] = 1:
The reaction is carried out at a ratio of 0 to 1: 9 (molar ratio). If the molar ratio exceeds 1: 9, a self-condensate of an infusible aromatic hydroxycarboxylic acid is likely to be formed, and the physical properties of the obtained polymer deteriorate.

Preferably, the reaction is carried out such that [aromatic diol]: [aromatic hydroxycarboxylic acid] = 1: 0 to 1: 1.

The acylation reaction is carried out at the reflux temperature of the acid anhydride or the produced acid. Taking the acetylation reaction as an example, the reaction is carried out at the reflux temperature of acetic anhydride or the acetic acid formed, for example, 120 to 150 ° C. If the reaction temperature is lower than 120 ° C, the acetylation reaction will not proceed sufficiently. The reaction time is usually 10 minutes to 10 hours, preferably 30 minutes to 1 hour. If it is less than 10 minutes, the acetylation reaction will not proceed sufficiently. The reaction pressure is usually under a dry nitrogen atmosphere. Nitrogen pressure may be applied. Further, if necessary, a catalyst such as sulfuric acid, sodium acetate, ferrous acetate, iron powder or the like may be used.

Next, the acylation reaction mixture is reacted with an aromatic hydroxycarboxylic acid to form an oligomer. At this time, the aromatic hydroxycarboxylic acid to be reacted may be the same as or different from the one used in the acylation reaction.

The aromatic hydroxycarboxylic acid is allowed to react 0.1 to 2 times by mole with respect to the aromatic diol. It is preferably twice the molar amount. If the amount exceeds 2 times the molar amount, unreacted aromatic hydroxycarboxylic acid remains, and the sublimation or decarboxylation reaction easily proceeds.

An oligomer is produced by the deoxidation reaction of the reaction mixture acylated by the acylation reaction and the aromatic hydroxycarboxylic acid added at this time.

The reaction temperature is usually 200 to 350 ° C, preferably 230 to 280 ° C,
If the temperature is below 200 ° C, the reaction will not proceed sufficiently. When the temperature exceeds 350 ° C, the decarboxylation reaction of unreacted aromatic hydroxycarboxylic acid proceeds. The reaction time is usually from 230 to 280 ° C. and from several tens of minutes to 10 hours, preferably from several tens of minutes to 2 hours. If it is less than tens of minutes, the reaction does not proceed sufficiently. The reaction proceeds almost completely in 2 hours. This deoxidation reaction is usually performed under a nitrogen stream.
You may apply pressure. Preferably, the pressure is reduced several minutes before the completion of the reaction, and the acid remaining in the reaction system is removed to the outside of the system. Also,
If necessary, a polycondensation catalyst composed of a compound such as Zn, Sn, Ti, Ni, Mn, Sb may be used.

Then, the resulting oligomer of the formula HOOC-Ar ₃ -COOH (Ar ₃ represents a divalent group having an aromatic ring)
The desired wholly aromatic polyester is obtained by directly polycondensing an aromatic dicarboxylic acid represented by the formula (1) with a catalyst, if necessary.

Specific examples of the aromatic dicarboxylic acid include the following compounds.

Terephthalic acid, isophthalic acid, 4,4'-biphenyldicarboxylic acid, 4,4 "-p-terphenyldicarboxylic acid, 4,
4'-isopropylidene dibenzoic acid, 4,4'-trans dicarboxylic acid, 4,4'-trans stilbene dicarboxylic acid, 4,
4'-diphenylmethane dicarboxylic acid, 4,4'-diphenyl ether dicarboxylic acid, 4,4'-diphenyl ketone dicarboxylic acid, 4,4'-diphenyl sulfone dicarboxylic acid, 4,4'-azobenzene dicarboxylic acid, p-phenylene diacetic acid 1,5-biphenylenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid,
1,5-naphthalenedicarboxylic acid, 2,6-anthraquinone dicarboxylic acid, 1,4-anthraquinone dicarboxylic acid, 1,5-
Anthraquinone dicarboxylic acid, an imide ring precursor (C), (D), (E) represented by the following formula: (The carboxyl group involved in the direct polycondensation reaction is located at the 4-position or 5-position on the benzene ring with respect to the amide group.) (The carboxyl group involved in the direct polycondensation reaction is located at the 4-position or 5-position on the benzene ring with respect to the amide group.) (The carboxyl group is at the p-position or the m-position with respect to the amide group.
Located in the place. ) N- (4-carboxyphenyl) trimellitimide,
N- (3-carboxyphenyl) trimellitimide,
2,7-furandicarboxylic acid, 3,3 '-(2,3-thiophene) dipropionic acid, 1,1-dioxo-2,5-cis-tetrahydrothiophene dicarboxylic acid, 2,6-4H-pyrandicarboxylic acid , 2,6-cis-tetrahydrothiopyrandicarboxylic acid, 2,8-dibenzofurandicarboxylic acid, 5,5'-dioxo-2,8-dibenzothiophenedicarboxylic acid, 9-
Oxo-2,7-xanthene dicarboxylic acid, 1,6-dibenzo [1,4] dioxin dicarboxylic acid, 2,8-phenoxathiine dicarboxylic acid, 2,6-thianthrene dicarboxylic acid, 10
-Oxo-10-phenyl-2,8-phenoxaphosphine dicarboxylic acid, 2,4-pyrrole dicarboxylic acid, 2,5-indole dicarboxylic acid, 2,4-pyridinedicarboxylic acid, 2,6
-Quinoline dicarboxylic acid, 2,5-piperazine dicarboxylic acid, 5,5 ', 10,10'-tetraoxy-2,7-thianthylene dicarboxylic acid and the like, preferably terephthalic acid and isophthalic acid, imide ring precursor Body C, imide ring precursor D,
The imide ring precursor E is used. You may use these in mixture of 2 or more types.

As the catalyst, sodium, potassium, calcium, titanium, manganese, iron, cobalt, nickel, copper, zinc,
A salt of germanium, tin, phosphorus, antimony, or the like, a metal compound such as an oxide, or an organometallic compound can be used. Preferably, a salt of antimony, titanium, tin or germanium of Group IV and Group V of the periodic table, a metal compound such as an oxide, or an organometallic compound is used.

Particularly preferably, tin compounds are used. In particular,
For example, dibutyltin oxide, dimethyltin oxide, diphenyltin oxide, dibutyltin diacetate, tributyltin acetate, triphenyltin acetate, triphenyltin chloride, tributyltin chloride, tetrabutyltin, n-butylstannoic acid, dimethoxytin, acetic acid primary Examples include tin, stannous sulfate, stannous oxalate, titanium dioxide, titanium alkoxide, tetrabutyl titanate, tetraisopropyl titanate, tetraphenyl titanate, dicyclopentadienyl diphenyl titanium, antimony trioxide, and germanium dioxide. , But not limited to these. The most preferred catalyst is n-butylstannoic acid.

The amount of catalyst used is usually based on the total molar amount of the monomer reactants.
The amount used is 0.005 to 3 mol%, preferably 0.01 to 0.1 mol%. If it is less than 0.005 mol%, the polymerization reaction may not proceed, and if it exceeds 3 mol%, the produced polymer tends to be thermally deteriorated.

As for the reaction conditions for direct polycondensation, it is preferable to add an equimolar amount of an aromatic diol (HO—Ar ₁ —OH) using an aromatic dicarboxylic acid.

While stirring the entire reaction system, the reaction is usually performed at 200 to 380 ° C. for several minutes to 24 hours under a nitrogen gas atmosphere.

The preferred reaction temperature is 300 to 350 ° C, and the preferred reaction time is
30 minutes to 2 hours.

If the reaction temperature is lower than 200 ° C, the reaction may not proceed sufficiently, and if the reaction temperature exceeds 380 ° C, the polymer may be thermally decomposed. If the reaction time is less than a few minutes, the reaction may not proceed sufficiently, and if the reaction time exceeds 24 hours, the polymer may be thermally decomposed. The reaction pressure may be nitrogen pressure or reduced pressure may be applied.

Then, while stirring the whole, the reaction is usually performed at a vacuum degree of 100 mmHg or less, a reaction temperature of 200 to 380 ° C., and a reaction time of 1 minute to 24 hours.

The preferred reaction temperature is 300-350 ° C, the preferred reaction time is 1
Minutes to 1 hour. If the reaction temperature is lower than 200 ° C, the reaction may not proceed sufficiently, and if the reaction temperature exceeds 380 ° C, the polymer may be thermally decomposed. Also, the reaction time is 1
If it is less than minutes, the reaction may not proceed sufficiently, and if the reaction time exceeds 24 hours, the polymer may be thermally decomposed.
If the degree of vacuum exceeds 100 mmHg, the reaction may not proceed sufficiently.

〔Example〕

Hereinafter, the present invention will be described in detail based on examples, but the present invention is not limited thereto.

In the following examples, the evaluation method was as follows.

1. Calculation method of decarboxylation reaction rate.

Phenol in the distillate distilled out of the system during the direct polycondensation step was quantitatively analyzed by high performance liquid chromatography. The decarboxylation rate of the aromatic hydroxycarboxylic acid was calculated from the obtained quantitative value of phenol.

2. Calculation method of yield: Yield (%) = (Yield [g] / Theoretical yield [g]) x 100 3. Evaluation method of bending characteristics and heat distortion temperature.

Molding of test piece Using injection molding machine (Toshiba IS45P), molding temperature 250-350
Molding was carried out at a mold temperature of 120 ° C.

Measurement method Bending characteristics Using a HTM250 manufactured by Toyo Seiki Co., Ltd., a 127 × 12.7 × 3.2 mm test piece was measured at 23 ° C.

Other test conditions were in accordance with ASTM D790.

Heat Deflection Temperature (HDT) Using a device manufactured by Toyo Seiki Co., Ltd., a test piece of 127 × 12.7 × 3.2 mm was used and the load was measured at 18.6 kg / cm ² .

Other test conditions were in accordance with ASTM D648.

4. Melt viscosity The molecular weight was evaluated by the melt viscosity at 380 ° C.

Equipment: Koka type flow tester Shimadzu flow tester CFT-500 Measuring conditions Die: Diameter 1.0mm, L / D = 10 Extrusion pressure: 10kgf / cm ² Temperature rising rate: 5 ° C / min Example 1 4,4′-dihydroxy 0.3 mol of diphenyl (55.87 g) and 0.6 mol of acetic anhydride (56.41 ml) were put into a 500 ml separable flask, and the amount was about 1 at 140 ° C.
While stirring for an hour, acetic anhydride and acetic acid produced were refluxed to carry out a reaction.

Then, 0.6 mol (82.87 g) of p-hydroxybenzoic acid was added, and the temperature was raised to 280 ° C. with stirring under a nitrogen atmosphere to distill off acetic acid to obtain an oligomer represented by the general formula (I). Terephthalic acid 0.24 mol (39.87 g) Isophthalic acid 0.06 mol (9.97 g) Catalyst (n-butylstannoic acid) 0.05 mol% (0.1253 g) was added, and the temperature was raised to 350 ° C with stirring under a nitrogen stream at 350 ° C. The mixture was stirred for several minutes at room temperature, a small amount of acetic acid and water were distilled off, and the polymerization was allowed to proceed. Then, the pressure inside the system was reduced to 10 mmHg, and the polymerization was allowed to proceed for 10 minutes, and further at a reduced pressure of 2 mmHg for 10 minutes. The produced polymer was taken out in a molten state.

This polymer exhibited optical anisotropy in the molten state. Table 1 shows the results of decarboxylation reaction rate of aromatic hydroxycarboxylic acid, polymer yield, bending property, melt viscosity at 380 ° C, and heat distortion temperature.

Example 2 Instead of the catalyst, n-butylstannoic acid 0.05 mol% (0.1253 g), n-dibutyltin oxide 0.05 mol% (0.14 g
Example 1 was repeated except that 94 g) was used. This polymer exhibited optical anisotropy in the molten state. The evaluation results are shown in Table-1.

Example 3 4,4'-Dihydroxyphenyl 0.24 mol (44.69 g) p-Hydroxybenzoic acid 0.24 mol (33.15 g) Acetic anhydride 0.72 mol (67.70 ml) was placed in a 500 ml separable flask and the temperature was about 1 at 140 ° C. While stirring for an hour, acetic anhydride and acetic acid produced were refluxed to carry out a reaction.

Next, 0.48 mol (66.30 g) of p-hydroxybenzoic acid was added, the temperature was raised to 280 ° C. with stirring under a nitrogen atmosphere, and the acetic acid was distilled off to obtain an oligomer represented by the general formula (I). Acid 0.18 mol (29.90 g) Isophthalic acid 0.06 mol (9.970 g) Catalyst (n-butyltin oxide) 0.05 mol% (0.1494
g) was charged, the temperature was raised to 350 ° C. with stirring under a nitrogen stream, the mixture was stirred at 350 ° C. for several minutes, a small amount of acetic acid and water were distilled off, and polymerization was allowed to proceed. Then, the pressure inside the system was reduced to 10 mmHg, and the polymerization was allowed to proceed for 10 minutes, and further at a reduced pressure of 2 mmHg for 10 minutes. The produced polymer was taken out in a molten state. This polymer exhibited optical anisotropy in the molten state. The evaluation results are shown in Table-1.

Example 4 0.3 mol (55.87 g) of 4,4'-dihydroxydiphenyl 0.6 mol (56.41 ml) of acetic anhydride was placed in a 500 ml separable flask, and acetic anhydride and acetic acid formed were stirred at 140 ° C for about 1 hour. Was refluxed to carry out the reaction.

Next, p-hydroxybenzoic acid 0.564 mol (77.90 g) N- (4-carboxyphenyl) -4-hydroxyphthalimide 0.036 mol (10.20 g) was added, and the mixture was heated to 280 ° C while stirring under a nitrogen atmosphere, and acetic acid was added. Was distilled off to obtain an oligomer represented by the general formula (I).

Then terephthalic acid 0.24 mol (39.87g) isophthalic acid 0.06 mol (9.97g) catalyst (tributyltin acetate) 0.05 mol% (0.2094
g) was charged, the temperature was raised to 350 ° C. with stirring under a nitrogen stream, the mixture was stirred at 350 ° C. for several minutes, a small amount of acetic acid and water were distilled off, and polymerization was allowed to proceed. Then, the pressure inside the system was reduced to 10 mmHg, and the polymerization was allowed to proceed for 10 minutes, and further at a reduced pressure of 2 mmHg for 10 minutes. The produced polymer was taken out in a molten state. This polymer exhibited optical anisotropy in the molten state. The evaluation results are shown in Table-1.

Comparative Example 1 After acetylation of an aromatic diol, which is a feature of this method,
An example is shown in which the monomers are collectively charged to carry out the polymerization except the step of forming the oligomer.

p-Hydroxybenzoic acid 0.6 mol (82.87g) 4,4'-dihydroxydiphenyl 0.3 mol (55.87g) Terephthalic acid 0.24 mol (39.87g) Isophthalic acid 0.06 mol (9.97g) Catalyst (n-butylstannoic acid) 0.05 mol% (0.1253 g) was charged, the temperature was raised to 350 ° C. with stirring under a nitrogen stream, the mixture was stirred at 350 ° C. for several minutes, a small amount of phenol and water were distilled off, and the polymerization was allowed to proceed. Then, the pressure inside the system was reduced to 10 mmHg, and the polymerization was allowed to proceed for 10 minutes, and further at a reduced pressure of 2 mmHg for 10 minutes. The produced polymer was taken out in a molten state. This polymer showed optical anisotropy in the molten state. The evaluation results are shown in Table-1.

Comparative Example 2 After acetylation of aromatic diol, which is a feature of this method,
An example is shown in which the monomers are collectively charged to carry out the polymerization except the step of forming the oligomer.

p-Hydroxybenzoic acid 0.72 mol (99.45g) 4,4'-dihydroxydiphenyl 0.24 mol (44.69g) Terephthalic acid 0.18 mol (29.90g) Isophthalic acid 0.06 mol (9.97g) Catalyst (n-butylstannoic acid) 0.05 mol% (0.1253 g) was charged, the temperature was raised to 350 ° C. with stirring under a nitrogen stream, the mixture was stirred at 350 ° C. for several minutes, a small amount of phenol and water were distilled off, and the polymerization was allowed to proceed. Then, the pressure inside the system was reduced to 10 mmHg, and the polymerization was allowed to proceed for 10 minutes, and further at a reduced pressure of 2 mmHg for 10 minutes. The produced polymer was taken out in a molten state. This polymer exhibited optical anisotropy in the molten state. The evaluation results are shown in Table 1.

EFFECT OF THE INVENTION According to the present invention, aromatic hydroxycarboxylic acid, aromatic diol, and aromatic dicarboxylic acid are used as raw materials, the decarboxylation reaction of aromatic hydroxycarboxylic acid is suppressed, and high strength is obtained by direct polycondensation. Can be obtained in high yield.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Jun Wakabayashi 1660 Kamisen, Sodegaura-cho, Kimitsu-gun, Chiba Idemitsu Petrochemical Co., Ltd. (56) References JP 63-277231 (JP, A) JP 63 -196624 (JP, A) JP-A-63-182334 (JP, A)

Claims (3)

[Claims] 1. A method for producing a wholly aromatic polyester by reacting an aromatic hydroxycarboxylic acid, an aromatic diol and an aromatic dicarboxylic acid, wherein an aromatic diol or an aromatic diol and an aromatic hydroxycarboxylic acid are mixed with R ^1-. CO
After acylation with an acid anhydride represented by —O—CO—R ¹ (wherein R ¹ is an alkyl group having 1 to 10 carbon atoms), an aromatic hydroxycarboxylic acid is reacted to obtain the reaction product and the aromatic compound. A process for producing a wholly aromatic polyester, which comprises polycondensing an aromatic dicarboxylic acid. 2. The method for producing a wholly aromatic polyester according to claim 1, wherein the polycondensation is carried out in the presence of a metal compound or an organometallic compound. 3. The method for producing a wholly aromatic polyester according to claim 1, wherein the aromatic diol is a diol represented by the following formula. (In the formula, X is —O— or SO ₂ —, m is 0 or 1, and n is 0.
Or 1. )