JP3484595B2 - Method for producing liquid crystal polyester - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a liquid crystal polyester. More specifically, the present invention relates to a method for producing a liquid crystal polyester of high quality, particularly excellent in heat resistance, by performing efficient stirring in a melt polycondensation reaction.

[0002]

2. Description of the Related Art In recent years, the demand for higher performance of plastics has been increasing, and many polymers having various new properties have been developed and put on the market. Among them, the liquid crystal polyester of optical anisotropy, which is characterized by parallel arrangement of molecular chains, has been attracting attention because it has excellent fluidity and mechanical properties.

As a method for producing a liquid crystal polyester, as disclosed in JP-A-1-149825, when the viscosity increases, the number of stirring is decreased to control the polymerization reaction temperature, and JP-A-4-225023. As disclosed in the publication, the shear rate on the wall surface of the can is 10 to 10.
It is known to polymerize while stirring the reaction product at a rate of 100 (1 / second) while scraping it.

[0004]

However, although it is possible to produce a liquid crystal polyester excellent in quality by the conventional polymerization method, the monomer and oligomer remaining in the can are repeatedly batch-polymerized after several batch polymerizations. The polymer undergoes heat history to become a foreign substance that does not melt even at a temperature above the melting point of normal polymer, and is mixed into the polymer when discharged from the can after completion of polymerization, which adversely affects the physical properties of the resulting liquid crystalline polyester. I found that I had to clean the inside of the can. Therefore, the present invention provides a method for producing a liquid crystal polyester having high quality, particularly excellent heat resistance, by improving the productivity by reducing the amount of monomers and oligomers remaining in the can and prolonging the cleaning cycle in the can. To do.

[0005]

The present inventors have arrived at the present invention as a result of extensive studies to solve the above problems. That is, in the present invention, when a liquid crystal polyester is produced by a deacetic acid polycondensation reaction using a polymerization device having a raw material inlet, a stirrer and a jacket, the polycondensation reaction is performed at a shear rate of 150 to 1000 (1 / sec). A method for producing a liquid crystal polyester, which comprises a step of mixing reactants so that the liquid crystal polyester is one or more kinds selected from the following a to f as a raw material, and acetic anhydride is added together with the raw material as necessary. A method for producing the above liquid crystal polyester, which is produced by: a. Hydroxycarboxylic acid b. Acetoxycarboxylic acid c. Dihydroxy compound d. Diacetoxy compound e. Dicarboxylic acid f. Polyester consisting of dioxy units and dicarbonyl units From the start of stirring and heating, until the distillate rate expressed as a percentage of the total amount of distillate theoretically calculated reaches 90%. Of the liquid crystal polyester, wherein the reaction product is mixed for 10% or more of the time so that the shear rate is 150 to 1000 (1 / second), and the distillation rate is represented by the following formula (1). The method for producing the above liquid crystal polyester represented by the following formula: Distillation rate (%) = Distillate amount (g) / {[(moles of acetic anhydride added-moles of hydroxyl group in raw material) x acetic anhydride Molecular weight of + ((number of moles of hydroxyl group in raw material x molecular weight of acetic acid x 2) + number of moles of acetyl group in raw material x molecular weight of acetic acid] (g)} x 100 (%) ··· (1) (wherein If acetic anhydride is not used, "added acetic anhydride Number of moles-Number of moles of hydroxyl groups in raw material x Molecular weight of acetic anhydride + (Number of moles of hydroxyl groups in raw material x Molecular weight of acetic acid x
2) "is calculated as 0, and when neither acetoxycarboxylic acid nor diacetoxy compound is used," moles of acetyl group x acetic acid molecular weight "in the raw material is calculated as 0) After starting stirring and heating The shear rate is 150 to 1 for 80% or more of the time until the distillation rate reaches 20%.
The method for producing a liquid crystal polyester, wherein the reactants are mixed so as to be 000 (1 / second), and the distillation rate from the start of stirring and temperature rise to 20% to 50%. The shear rate is 150 to 1 for 80% or more of the time.
The method for producing a liquid crystal polyester, characterized in that the reactants are mixed so as to be 000 (1 / second), from the start of stirring and temperature increase until the distillation rate reaches 50% to 90%. The shear rate is 150 to 1 for 80% or more of the time.
The method for producing a liquid crystal polyester, wherein the reactants are mixed in an amount of 000 (1 / sec), and the liquid crystal polyester is a liquid crystal polyester having an ethylenedioxy unit. The method and liquid crystal polyester have the following (I) and (I
The method for producing a liquid crystal polyester is characterized in that the liquid crystal polyester comprises the structural units I), (III) and (IV).

[0006]

[Chemical 4] (However, R ₁ in the formula is

[Chemical 5] R ₂ represents one or more groups selected from

[Chemical 6] And one or more groups selected from Further, in the formula, X represents a hydrogen atom or a chlorine atom, and the structural units (II) and (II
(I) and structural unit (IV) are substantially equimolar)

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The liquid crystal polyester produced by the present invention is a polymer capable of forming anisotropy when melted, for example, an oxycarbonyl unit such as an aromatic oxycarbonyl unit, an aromatic dioxy unit, an ethylenedioxy unit and the like. Polyesters having a melt anisotropy composed of units selected from dioxy units, dicarbonyl units such as aromatic dicarbonyl units, and the like. Above all, the above (I), (I
A liquid crystal polyester comprising the structural units I), (III) and (IV) is preferable, and the structural unit (I) is p
-A structural unit of a polyester produced from hydroxybenzoic acid, wherein the structural unit (II) is 4,4'-dihydroxybiphenyl, 3,3 ', 5,5'-tetramethyl-4,
4'-dihydroxybiphenyl, hydroquinone, t-
Butyl hydroquinone, phenyl hydroquinone, 2,
A structural unit formed from an aromatic dihydroxy compound selected from 6-dihydroxynaphthalene, 2,7-dihydroxynaphthalene, 2,2-bis (4-hydroxyphenyl) propane and 4,4′-dihydroxydiphenyl ether is replaced by a structural unit ( III) is a structural unit formed from ethylene glycol, and structural unit (IV) is terephthalic acid, isophthalic acid, 4,4'-diphenyldicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 1,2-bis (phenoxy) ethane. -4,4'-dicarboxylic acid, 1,
2-bis (2-chlorophenoxy) ethane-4,4'-
Structural units formed from an aromatic dicarboxylic acid selected from dicarboxylic acid and diphenyl ether dicarboxylic acid are shown below. Of these, especially R ₁

[Chemical 7] Is 70% by mole or more of the structural unit (II), R ₂
But

[Chemical 8] Particularly preferably those which account for 70 mol% or more of the structural unit (IV).

The above structural units (I), (II), (III),
The copolymerization amount of (IV) is arbitrary. However, from the viewpoint of fluidity, the following copolymerization amount is preferable.

That is, from the viewpoint of heat resistance, flame retardancy and mechanical properties, the total of the structural units (I) and (II) is 60 to 95 mol% of the total of (I), (II) and (III). Is preferable, and 82-93 mol% is more preferable. Further, the structural unit (III) is preferably 40 to 5 mol% of the total of (I), (II) and (III), and more preferably 18 to 7 mol%. Further, the molar ratio [(I) / (II)] of the structural units (I) and (II) is preferably 75/25 to 95/5, more preferably 78 from the viewpoint of the balance between heat resistance and fluidity. / 22 to 93/7. Also, the structural unit (I
V) is substantially equimolar to the sum of structural units (II) and (III).

When polycondensing the above preferred polyester, 3,3'-diphenyldicarboxylic acid, 2,2'-, in addition to the components constituting the structural units (I) to (IV), are used.
Aromatic dicarboxylic acids such as diphenyldicarboxylic acid, adipic acid, azelaic acid, sebacic acid, aliphatic dicarboxylic acids such as dodecanedioic acid, alicyclic dicarboxylic acids such as hexahydroterephthalic acid, chlorohydroquinone,
Aromatic diols such as methylhydroquinone, 4,4'-dihydroxydiphenyl sulfone, 4,4'-dihydroxydiphenyl sulfide, 4,4'-dihydroxybenzophenone, 1,4-butanediol, 1,6-hexanediol, neopentyl Aliphatic and alicyclic diols such as glycol, 1,4-cyclohexanediol and 1,4-cyclohexanedimethanol, and aromatic hydroxycarboxylic acids such as m-hydroxybenzoic acid and 2,6-hydroxynaphthoic acid, and p-amino Phenol, p
-Aminobenzoic acid or the like can be further copolymerized within a range not impairing liquid crystallinity.

Some of the liquid crystal polyesters produced by the present invention can measure the logarithmic viscosity in pentafluorophenol, in which case the concentration of 6 g at a concentration of 0.1 g / dl.
The value measured at 0 ° C is preferably 0.3 dl / g or more,
0.5 to 3.0 dl / g is particularly preferable.

The liquid crystal polyester of the present invention has a melt viscosity of preferably 10 to 20,000 poise, more preferably 20 to 10,000 poise.

The melt viscosity is the melting point (Tm) +10.
It is a value measured by a flow tester CFT-500 manufactured by Shimadzu Corporation under the condition of a shear rate of 1,000 (1 / second) under a condition of ° C.

Here, the melting point (Tm) is a differential scanning calorimeter, and the temperature of the polymerized polymer is measured from room temperature to 20 ° C. /
After observing the endothermic peak temperature (Tm1) observed when measured under the temperature rising condition of 1 minute, after holding at the temperature of Tm1 + 20 ° C for 5 minutes, after cooling to room temperature under the temperature decreasing condition of 20 ° C / minute, The endothermic peak temperature (Tm2) observed when measured again under the temperature rising condition of 20 ° C / min.

In the present invention, the liquid crystal polyester is produced by a deacetic acid polymerization reaction. The reaction for producing the liquid crystal polyester is not particularly limited except that it is carried out by a deacetic acid polymerization reaction, and a known method can be adopted.

When roughly classified, a method of using an acetylated product of a hydroxyl group-containing monomer such as a hydroxycarboxylic acid or a dihydroxy compound as a part or the whole of a raw material, and using a hydroxyl group-containing monomer as a part of the raw material There is a method of adding acetic anhydride or a method of replacing a part of the hydroxyl group-containing monomer with an acetylated product in the latter method.

As the raw material for producing the liquid crystal polyester, one or more selected from the following a to f can be selected and used. Hydroxycarboxylic acid b. Acetoxycarboxylic acid c. Dihydroxy compound d. Diacetoxy compound e. Dicarboxylic acid f. Polyester consisting of dioxy units and dicarbonyl units a. Examples of the hydroxycarboxylic acid include aromatic hydroxycarboxylic acid and alicyclic hydroxycarboxylic acid, and b. Examples of acetoxycarboxylic acid include acetylated products of the above hydroxycarboxylic acids. c. As the dihydroxy compound, an aromatic dihydroxy compound,
Alicyclic dihydroxy compounds and aliphatic dihydroxy compounds, and the like, and d. Examples of the diacetoxy compound include c. Examples thereof include diacetylated dihydroxy compounds.

E. Examples of the dicarboxylic acid include aromatic dicarboxylic acid, alicyclic dicarboxylic acid, and aliphatic dicarboxylic acid.

F. Examples of the polyester composed of dioxy units and dicarbonyl units include polyesters prepared by polymerizing alkylene glycol and aromatic dicarboxylic acid, and so-called oligomers and bis (hydroxyalkyl) esters may be used.

As the raw materials of the above a to f, those which produce the structural units represented by the structural units (I) to (IV) are preferable.

When a hydroxycarboxylic acid or a dihydroxy compound is used in the production of liquid crystal polyester, acetic anhydride is usually added together with the raw material. Acetic anhydride is usually 1 to 1.3 times the molar amount of hydroxycarboxylic acid or the hydroxyl group of the dihydroxy compound, particularly 1.0
It is preferable to add 5 to 1.2 times the molar amount.

Specifically, the methods shown in the following (i) and (ii) are preferable, but the method (ii) is particularly preferable.

(I) p-acetoxybenzoic acid and 4,
Polyesters or oligomers of aromatic dicarboxylic acid such as 4'-diacetoxybiphenyl and aromatic dihydroxy compound such as paradiacetoxybenzene and aromatic dicarboxylic acid such as terephthalic acid, ethylene glycol and aromatic dicarboxylic acid, or bis (β of aromatic dicarboxylic acid) -Hydroxyethyl) ester by a deacetic acid polycondensation reaction.

(Ii) p-hydroxybenzoic acid, 4,4
′ -Dihydroxybiphenyl, aromatic dihydroxy compounds such as hydroquinone, aromatic dicarboxylic acids such as acetic anhydride and terephthalic acid, and polyesters or oligomers of ethylene glycol and aromatic dicarboxylic acids or bis (β-hydroxy of aromatic dicarboxylic acids A method of producing a product by a deacetic acid polycondensation reaction after reacting with an ethyl ester to acetylate a phenolic hydroxyl group.

Polymerization proceeds even if this deacetic acid reaction is carried out in the absence of a catalyst, but stannous acetate, tetrabutyl titanate,
In some cases, it may be preferable to add a metal compound such as potassium acetate, antimony trioxide, magnesium or sodium acetate as a catalyst.

In the present invention, when a liquid crystal polyester is produced by a deacetic acid polycondensation reaction, a polymerization apparatus having a raw material charging port, a stirring device and a jacket is used. With respect to the polymerization apparatus, the initial reaction to polycondensation can be carried out in a single-stage reaction tank or in a multi-stage reaction tank.

When the raw material of the above reaction (i) is used, the reaction is often carried out in one step, and the temperature is raised to 250 ° C. to 400 ° C. under normal pressure or pressure and nitrogen atmosphere, and then 250 ° C.
Polycondensation is performed under reduced pressure at 400 ° C.

When the method (ii) is carried out, the contact with the acetylating agent is carried out at 80 ° C. under normal pressure or pressure, under nitrogen atmosphere.
The reaction is carried out at ˜300 ° C., preferably at 130 ° C. to 150 ° C. for 1 hour or more. After the reaction at 130 ° C. to 150 ° C., the temperature is raised to 200 ° C. to 300 ° C. to distill off acetic acid, which is a by-product of the acetylation reaction, and unreacted acetic anhydride. Then, polycondensation is performed under reduced pressure at 250 ° C to 400 ° C.

In the production method of the present invention, it is important to include a step of carrying out the polycondensation reaction under specific stirring conditions, and preferably perform the initial polycondensation reaction under specific stirring conditions. The initial polymerization reaction usually refers to a step before the polycondensation under reduced pressure in the above example, for example, until the polyester oligomer is formed.

The stirring condition is such that the shear rate at the stirring blade and the wall surface of the can is a value determined by the following equation (2) of 150 to 1.
000 (1 / second).

Shear rate (1 / sec) = 2 × 2 × 3.14 × number of stirring (rotation / sec) × can inner diameter × can inner diameter / (can inner diameter × can inner diameter−stirring blade outer diameter × stirring blade outer diameter) (2) When the deacetic acid polycondensation reaction of the liquid crystal polyester is produced by the above method, a distillate such as acetic acid is usually calculated by the denominator of the above formula (1). When the amount of about 85 to 90% of the theoretical amount of distillation is distilled, a polyester oligomer having a degree of polymerization of about 2 to 4 is produced. In the present invention, it is preferable to stir the reaction product at the above shearing rate during the initial polycondensation reaction, and the time from the start of stirring and heating until the distillation rate reaches 90%. 10%
The shear rate obtained from the above equation (2) is 1 for the above time.
It is more preferable that the stirring is performed so as to be 50 to 1000 (1 / second).

Here, the distillate rate means the ratio of the distillate to the total amount of the distillate theoretically calculated, expressed as a percentage, and it can be specifically obtained by the following formula (1).

Distillation rate (%) = distilled liquid amount (g) / [[(mol number of added acetic anhydride-mol number of hydroxyl group in raw material) × molecular weight of acetic anhydride + (mol of hydroxyl group in raw material) Number x molecular weight of acetic acid x 2) + number of moles of acetyl group in raw material x acetic acid molecular weight] (g)} x 100 (%) (1) (wherein acetic anhydride is not used, "addition Number of moles of acetic anhydride-Number of moles of hydroxyl group in raw material) x Molecular weight of acetic anhydride + (Number of moles of hydroxyl group in raw material x Molecular weight of acetic acid x
2) "is calculated as 0, and when neither acetoxycarboxylic acid nor diacetoxy compound is used," the number of moles of acetyl group x acetic acid molecular weight "in the raw material is calculated as 0) In the above formula (1), "(Mol of acetic anhydride-mol of hydroxyl group in raw material) x molecular weight of acetic anhydride" is
It represents the theoretical amount by which excess acetic anhydride distills out when acetic anhydride is added in an amount that is more than 1 times the molar amount of the hydroxyl groups in the raw material. If this does not occur, no entry is made.

"Mole number of hydroxyl groups in raw material x molecular weight of acetic acid" represents the theoretical amount of acetic acid distilled when an acetylated product acetylated with acetic anhydride reacts with a carboxylic acid group, and "x2". "Represents the theoretical amount of acetic anhydride residue after the acetylation reaction, that is, the theoretical amount of acetic acid, and is not included if this is not distilled.

"Mole number of acetyl groups in raw material x molecular weight of acetic acid" represents the theoretical amount of acetic acid distilled when an acetylated product added as a raw material reacts with a carboxylic acid group.

For example, in the method (ii) using acetic anhydride, the distillation rate can be determined as follows.

Distillation rate (%) = distilled liquid amount (g) / [excess acetic anhydride amount + acetic acid amount generated when polymerization completely proceeds + acetic acid generated when acetylation completely proceeds] Amount] (g) x 100 (%) Among them, the distillation rate is 0% to 20%, 20% to 50%, and 50% after starting the stirring and temperature rise after adding the raw materials.
When it is divided into time to reach 90%, the shear rate on the stirring blade and the wall surface of the can is calculated to be 150 to 10% for at least 80% of the time.
It is preferable to carry out so as to be 00 (1 / second).
150 to 1000 for all times to reach 90%
Most preferably, it is performed at (1 / sec).

The stirring blade may have any shape as long as a good mixed state can be obtained, but a baffle plate is often attached to the liquid phase portion in the can to improve the mixed state. Further, for the purpose of reducing the amount of monomers and oligomers remaining in the can after the completion of the reaction, the blade attached to the stirring shaft is preferably within the reaction liquid surface during the reaction.

The liquid crystal polyester reactor used in the present invention is a reaction can equipped with a raw material inlet, a stirrer and an outlet, a condenser for condensing the vapor distilled from the reaction can during the reaction, a condensate receiving tank, and It is a vertical reactor that consists of a vacuum generator for vacuum polymerization.
An apparatus having at least one unit is preferable, and one having a shape in which the ratio of the vertical length to the horizontal length of the reaction can is more than 1 and less than 3 is preferable. When the reaction is performed in two or more cans, the reaction can is moved when the distillation rate obtained by the above formula reaches at least 80% or more, and the subsequent reaction is carried out at the shear rate of 10 to 100 (1
It is preferable to stir in such a direction that the reaction product is scraped at a rate of (1 / sec).

The characteristic feature of the liquid crystal polyester production method of the present invention is that the stirring rate is constant for a certain period of time until the distillation rate reaches a predetermined value, and the shear rate between the stirring blade and the wall surface of the can is 150 to 100.
0 (1 / sec), preferably 200 to 700 (1 / sec) are mixed for reaction. Shear rate is 150 (1
/ Sec), the charged raw materials are not sufficiently mixed, and as a result, a uniform reaction cannot be achieved. It gets shorter. If the shear rate exceeds 1000 (1 / sec), the liquid level will be greatly swelled by agitation, and the reaction product adheres to the inner wall surface of the can and accumulates due to splashing of the liquid, which shortens the cleaning cycle in the can.

[0041]

EXAMPLES The present invention will be described in more detail below with reference to examples.

Example 1 A reaction can 1 having an inner volume of 1.6 m ³ , an inner diameter of the can of 1.2 m, a distance between the inner wall surface of the can and a helical blade stirrer of 1 cm, and an inner volume of 0.
Using 2 cans of reaction can 2 of a double helical blade stirrer without a central axis having 8 m ³ , an inner diameter of the can of 1.1 m, and a bottom blade having a distance of 2 cm between the inner wall surface of the can and the stirring blade, the following can be used. Polymerized.

In the reaction can 1, p-hydroxybenzoic acid 220 was added.
kg, 4,4'-dihydroxybiphenyl 27.8k
g, polyethylene terephthalate 47.8 kg, terephthalic acid 24.8 kg and acetic anhydride 211.8 kg were charged, the mixture was stirred at 30 rpm for 5 minutes, and then the temperature started to be increased to 60
Rotation / min, after reaching 130 ℃ in 0.75 hours,
The reaction is performed at 130 ° C to 250 ° C for 5 hours, and then the reaction vessel 2 is moved to 2 while stirring at 30 rpm.
The reaction can 2 is heated to 250 ° C. to 320 ° C. over 1 hour, and the reaction can 2 is heated to 1 To.
The pressure was reduced to rr, and stirring was continued at 320 ° C. for 2 hours to complete the polycondensation reaction. After that, the inside of the two reaction cans was pressurized to 2 kg / cm ² , and the polymer was discharged in the form of strands through the mouthpiece into pellets. The distillation rate was 85% at the end of the reaction in the reaction can 1, reached 90% in 1 hour after moving to the reaction can 2, and the time until the distillation ratio reached 90% was 6 It was 0.75 hours. Further, the shear rate between the stirring blade and the wall surface of the can by stirring the reaction can 1 at 60 rpm is 38.
It was 0 (1 / second). The theoretical structural formula of this polymer is shown below.

[0044]

[Chemical 9] k / l / m / n = 80 / 7.5 / 12.5 / 20 By the above method, the polymer having the above composition was repeatedly batch polymerized. After the completion of the reaction, the phenomenon of becoming foreign matter by mixing in the discharged polymer appeared, so the polymerization was repeatedly interrupted and the inside of the can was washed.

Comparative Example 1 Two cans of a reaction can 1 having an inner volume of 1.6 m ³ , an inner diameter of the can of 1.2 m, and a distance between the inner wall surface of the can and the helical blade stirrer of 1 cm and a reaction can 2 similar to that of the first embodiment. The same amount of the raw material as in Example 1 was charged into the reaction can 1, stirred at 18 rpm, the temperature was started, and after reaching 130 ° C. in 1 hour, 5 to 130 ° C. to 250 ° C.
After reacting for a period of time, polymerization was carried out in the same manner as in Example 1 to form a discharge pellet. The distillation rate is 83 at the end of the reaction in reactor 1.
%, And reached 90% 1.5 hours after the transfer to the reaction can 2. The shear rate at the stirring blade of the reaction can 1 and the wall of the can at 18 revolutions / minute was 114 (1 / sec).

Repeated batch polymerization with the same polymer composition as in Example 1 interrupted the repeated polymerization because at the 10th batch, a substance having a melting point of the normal polymer or higher was mixed into the discharged polymer after the reaction to become a foreign substance. Then, the inside of the can was washed.

[0047]

According to the present invention, the productivity of liquid crystal polyester is improved and a high quality polymer having excellent heat resistance can be obtained.

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) C08G 63/00-63/91

Claims (9)

(57) [Claims] 1. When a liquid crystal polyester is produced by a deacetic acid polycondensation reaction using a polymerization device having a raw material inlet, a stirrer and a jacket, the polycondensation reaction is performed at a shear rate of 150 to 1000 (1 / sec). A method for producing a liquid crystal polyester, comprising the step of mixing the reactants so that 2. The production of a liquid crystal polyester according to claim 1, wherein the liquid crystal polyester is produced by using at least one selected from the following a to f as a raw material and, if necessary, adding acetic anhydride together with the raw material. Method. a. Hydroxycarboxylic acid b. Acetoxycarboxylic acid c. Dihydroxy compound d. Diacetoxy compound e. Dicarboxylic acid f. Polyester consisting of dioxy units and dicarbonyl units 3. The time from the start of stirring and temperature rise until the distillate ratio, which is a ratio of the distillate to the total amount of distillate theoretically calculated, expressed as a percentage reaches 90%. The method for producing a liquid crystalline polyester according to claim 2, wherein the reaction product is mixed for a time of at least 100% so that the shear rate is 150 to 1000 (1 / sec). 4. The method for producing a liquid crystal polyester according to claim 3, wherein the distillation rate is represented by the following formula (1). Distillation rate (%) = amount of distillate (g) / {[(moles of acetic anhydride added-moles of hydroxyl group in raw material) x molecular weight of acetic anhydride + (moles of hydroxyl group in raw material x acetic acid) Molecular weight x 2) + number of moles of acetyl group in raw material x acetic acid molecular weight] (g)} x 100 (%) (1) (In the formula, when acetic anhydride is not used, "added acetic anhydride is added. -Moles of hydroxyl group in raw material) x molecular weight of acetic anhydride + (moles of hydroxyl group in raw material x molecular weight of acetic acid x
2) "is calculated as 0, and when neither acetoxycarboxylic acid nor diacetoxy compound is used," the number of moles of acetyl group x acetic acid molecular weight "in the raw material is calculated as 0) 5. The distillation rate is 2 after starting stirring and heating.
The method for producing a liquid crystal polyester according to claim 3, wherein the reaction product is mixed so that the shear rate becomes 150 to 1000 (1 / sec) for 80% or more of the time until reaching 0%. 6. The distillation rate is 2 after the start of stirring and heating.
4. The liquid crystal polyester according to claim 3, wherein the reaction product is mixed so that the shear rate becomes 150 to 1000 (1 / sec) for 80% or more of the time until reaching 0% to 50%. Production method. 7. The distillation rate is 5 after the start of stirring and heating.
4. The liquid crystal polyester according to claim 3, wherein the reaction product is mixed so that the shear rate becomes 150 to 1000 (1 / sec) for 80% or more of the time until reaching 0% to 90%. Production method. 8. The method for producing a liquid crystal polyester according to claim 1, wherein the liquid crystal polyester is a liquid crystal polyester having an ethylenedioxy unit. 9. A liquid crystal polyester comprising the following (I), (II),
8. A method for producing a liquid crystal polyester according to claim 7, which is a liquid crystal polyester comprising the structural units (III) and (IV). [Chemical 1] (However, R ₁ in the formula is It represents one or more groups selected from, R ₂ is ## STR3 ## And one or more groups selected from Further, in the formula, X represents a hydrogen atom or a chlorine atom, and the structural units (II) and (II
The total of I) and the structural unit (IV) are substantially equimolar).