JP2001072750A - Aromatic liquid crystal polyester and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably obtain a high-molecular weight polyester by charging a reactor with a compound derived from 4-hydroxybenzoic acid and a compound derived from 6-hydroxy-2-naphthoic acid, polycondensing the compounds at a specified temperature, recovering the product when the flow temperature of the formed polyester reaches a specified temperature, solidifying the product, grinding the solid, and heat-treating the ground product at a specified temperature. SOLUTION: A reactor is charged with 80-20 mol% compound of formula I and 20-80 mol% compound of formula II, the compounds are polycondensed at 270-350 deg.C, and the formed polyester is recovered in a molten state when the flow temperature of the formed polyester reaches to a temperature higher than 210 deg.C and lower than the polycondensation temperature by at least 30 deg.C. The product is solidified, the solid is ground to a particle diameter of 3 mm or smaller, and the ground product in a solid state is heat-treated at 200-310 deg.C in an inert gas atmosphere. The flow temperature is the temperature at which the resin molten by heating at a rate of a temperature increase of 4 deg.C/min has a melt viscosity of 48,000 P when extruded from a nozzle having an inside diameter of 1 mm and a length of 10 mm under a load of 100 kgf/cm2. In the formula, R1 is H or the like; and R2 is H, CH3, or the like.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aromatic liquid crystalline polyester which is excellent in film formability (film forming property) and is suitable for use as a film, and a method for producing the same.

[0002]

2. Description of the Related Art In recent years, films made from various polymers have become indispensable in daily life. For example, various films such as a high strength film, a high elasticity film, an oxygen barrier film, a conductive film, a heat resistant film, and a light barrier film have been developed. Above all, films having an oxygen barrier property or a water vapor barrier property are permeating our lives as packaging materials regardless of whether they are for industrial use or for consumer use.

Conventionally, in this field, stretched films of polyolefins such as polyethylene and polypropylene, stretched films of polyethylene terephthalate (hereinafter abbreviated as PET), polyvinylidene chloride (hereinafter abbreviated as PVDC) films, saponified ethylene -A vinyl acetate copolymer (hereinafter abbreviated as EVOH) film or the like has been developed and used as a single layer or a multilayer film having two or more layers depending on the purpose and application. In many cases, multilayering is essential to maintain gas barrier properties, which is one of the factors that increase the manufacturing cost. In recent years, in the field of food packaging such as retort pouches, there is a tendency to perform high-temperature and short-time treatment for efficient sterilization, and a packaging material having high heat resistance is required. At present, PET films and the like on which silica, alumina, and the like are deposited are being developed, but in the future, issues remain regarding methods of separating and incineration of waste. A polyethylene naphthalate (hereinafter abbreviated as PEN) -based packaging material (container) having improved heat resistance and oxygen barrier properties of a PET film has been developed (for example, JP-A-8-113631,
However, the gas barrier property is insufficient for high gas barrier properties (oxygen permeability 1 cc / m ² · 24 hr · atm or less). . In addition, for EVOH, which is excellent in oxygen barrier property, but inferior in steam barrier property, the problem of steam barrier property is being solved by forming a multilayer film laminated with polyolefin or the like having excellent steam barrier property, Problems remain in heat resistance.

[0004] These fields are inexpensive and heat resistant,
Assuming future room temperature distribution, a resin material for films (high gas barrier material) having both high water vapor barrier properties and high oxygen barrier properties is desired. As a material having an oxygen barrier property and a water vapor barrier property, a liquid crystal polymer, in particular, a thermotropic liquid crystal polyester (hereinafter, may be abbreviated as LCP) has been attracting attention, and its film formation has been studied. For example, PET / p- having an aliphatic chain in the main chain
Hydroxybenzoic acid (hereinafter sometimes abbreviated as POB)
Liquid crystalline copolyester (JP-B 8-297)
No. 4) and other semi-aromatic liquid crystalline polyesters (Japanese Patent Publication No. 6-533383), and wholly aromatic liquid crystalline polyesters (JP-A-7-323506 and JP-A-7-251438). Films have been reported. In these studies, molecular orientation occurs in the flow direction (MD), which is a characteristic of LCP, and anisotropy in mechanical strength occurs in the direction (TD) perpendicular to the flow direction. The thickness of the LCP system having
It was difficult to obtain a thin film of less than μm.

The processing temperature of wholly aromatic LCP is 30
In many cases, the total aromatic liquid crystalline polyester having a heat resistance of more than 0 ° C. and a load deflection temperature (TDUL) of more than 250 ° C. requires a higher processing temperature of 350 ° C. or more, and specially designed expensive Requires a simple processing machine.
A film forming method from wholly aromatic polyester which forms an optically anisotropic melt upon melting is described in, for example, JP-B-62-58378.
Japanese Patent Publication No. JP-B-63-33450 describes inflation film formation and a film formation method using a T-die.
In each case, a processing temperature of 340 ° C. or higher is required, and there is still room for improvement in terms of the processing temperature.

On the other hand, as a production method for obtaining an aromatic polyester, a suspension polymerization method, an interfacial polymerization method, a solution polymerization method, a bulk melt polymerization method, and the like are known. There are problems such as removal, polymer washing, and drainage load. A method for producing a polyester obtained by copolymerizing different kinds of aromatic hydroxycarboxylic acids and an aromatic liquid crystalline polyester obtained from an aromatic hydroxycarboxylic acid, an aromatic dicarboxylic acid, and an aromatic diol usually employs bulk polymerization. ing. Bulk polymerization is excellent in economy, but since the equilibrium constant of the polycondensation reaction of polyester is smaller than that of polyamide, in order to advance the polycondensation reaction,
It is necessary to raise the reaction temperature or perform the reaction under reduced pressure to remove the by-products.

When the molecular weight is increased by using the reduced pressure polymerization method in combination, it is difficult to continuously recover the polymer if the molecular weight is increased until the desired melt tension is exhibited due to the relationship of the melt viscosity when the polymer is taken out. Or high temperature treatment, there is a problem of contamination of the polymer staying in the polymerization kettle or the discharge port. In the case of aromatic liquid crystalline polyesters with relatively low melting temperatures, the reaction is often carried out under reduced pressure in the latter stage, so there is a problem that it is difficult to obtain a high molecular weight resin in a stable state. (JP-A-8-192421). If unreacted raw materials or low-boiling compounds generated during polymerization remain in the aromatic liquid crystalline polyester, they may vaporize during molding and contaminate the environment, or they may be gradually generated from molded products and destroy the product mechanism. is there. If the unreacted raw materials and low-boiling compounds are vaporized during inflation film formation, there is a problem that the formation of bubbles is hindered and film formation becomes difficult. The present inventors have proposed a method for stably producing a heat-resistant polyester by a method of taking out a polyester in a molten state after melt polycondensation (Japanese Patent Laid-Open No. 2-69517) or a combination of this method and a solid phase polymerization method. A method for producing an aromatic polyester (JP-A-2-69518) has been proposed.

Having a molecular weight sufficient to exhibit mechanical strength,
A wholly aromatic liquid crystalline polyester which can be molded at a low temperature (320 ° C. or lower) is disclosed in JP-B-63-3888, and a semi-aromatic liquid-crystalline polyester is disclosed in JP-A-61-1022.
No. 34, and the like. As a film forming method using this, a method of forming a film at a high shear rate is disclosed in JP-A-2-3430, and a film forming method using a ring die or the like is described in US Pat. No. 4,975,312 and WO9015706. Although described, all of them show a method of relaxing the anisotropy peculiar to the liquid crystal polyester by a special molding method. These are currently expensive 6-hydroxy-2-
Because naphthoic acid is used, it is usually 2
It is required to reduce the thickness to 5 μm or less, preferably 15 μm or less. JP-A-2-3430 describes a method of forming an inflation film at a high shear rate by using a melt strength measured under a constant condition as one of technical factors as an important index in film formation. Although a film having a thickness of 16 μm to 22 μm is exemplified, a problem remains in making the film thinner. LCP resin-based film materials having high gas barrier properties and low-temperature processability of 320 ° C. or less have many problems for practical use.

[0009]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for producing an aromatic liquid crystalline polyester which has sufficient strength as a packaging material, has low-temperature processability, and is suitable for a film having excellent gas barrier properties. And to provide an aromatic liquid crystalline polyester obtained by this production method.

[0010]

Means for Solving the Problems The present inventors have intensively studied a method for producing an aromatic liquid crystalline polyester comprising two or more aromatic hydroxycarboxylic acid units and a method for increasing the molecular weight of the resin, and the conventional method has been developed. In comparison, a production method capable of stably producing the aromatic liquid crystalline polyester having a high molecular weight has been found, and by increasing the molecular weight, the melt tension (hereinafter, sometimes abbreviated as MT) can be increased. The inventors have found that the temperature dependency of the melt viscosity can be reduced, and have completed the present invention.

That is, according to the present invention, [1] a compound represented by the following formula (I) is charged into a reaction tank at a ratio of 80 to 20 mol% and a compound represented by the following formula (II) at a ratio of 20 to 80 mol%. At the time when the flow temperature of the produced aromatic liquid crystalline polyester reaches 210 ° C. or higher and 30 ° C. or lower than the polycondensation reaction temperature, the content of the reaction vessel A certain aromatic liquid crystalline polyester is recovered and solidified in a molten state, crushed into particles having a particle size of 3 mm or less, and heat-treated at 200 ° C. to 310 ° C. in an inert gas atmosphere in a solid state. The present invention relates to a method for producing a group III liquid crystalline polyester.

Embedded image (However, R ¹ represents a hydrogen atom, a formyl group, an acetyl group, a propionyl group or a benzoyl group, and R ² represents a hydrogen atom, a methyl group, an ethyl group, a propyl group, a benzyl group or a phenyl group.)

Embedded image (However, the definitions of R ¹ and R ² are the same as the respective definitions in formula (I). R in formulas (I) and (II)
¹ may be the same or different from each other, and R ² in the formula (I) and the formula (II) may be the same or different from each other. Here, the flow temperature is measured by a capillary rheometer, and the resin heated and melted at a heating rate of 4 ° C./min, under a load of 100 kgf / cm ² , an inner diameter of 1 mm and a length of 10 mm
mm when extruded from a nozzle having a melt viscosity of 48,
A temperature (° C.) indicating 000 poise. The present invention also relates to [2] a method for producing an aromatic liquid crystalline polyester obtained by subjecting the aromatic liquid crystalline polyester obtained by the heat treatment according to the above [1] to heat melting and granulation. . The present invention further provides [3] the method of the above [1] or [2], wherein the following repeating unit (A) is used in an amount of 75 to 25 mol% of the entire repeating unit, and the repeating unit (B) And a logarithmic viscosity of 4.0 dl.
/ G or more, the flow temperature is 320 ° C. or less, and the melt tension measured at a temperature 25 ° C. or more higher than the flow temperature is 3.0 g or more.

Embedded image

Embedded image Further, the present invention provides [4] the method according to the above [1] or [2], wherein the shear rate is 100 sec ^-1 or 100 sec at the flowing temperature of the aromatic liquid crystalline polyester.
The ^value of the ratio (viscosity 2 / viscosity 1) between the melt viscosity (viscosity 1) measured at ⁰ sec ^-1 and the melt viscosity (viscosity 2) measured at the same shear rate as viscosity 1 at a temperature 20 ° C. higher than the flow temperature is 1 , 0.20 to 0.80.

[0012]

Next, the present invention will be described in detail. The method for producing an aromatic liquid crystalline polyester according to the present invention is characterized in that the compound represented by the following formula (I) is 80 to 20 mol%, preferably 75 to 25 mol%, and the compound represented by the following formula (II) is 20 to 80 mol%. Mol%, preferably 25-75 mol%
, And a polycondensation reaction is performed at 270 to 350 ° C., and the flow temperature of the generated aromatic liquid crystalline polyester is 210 ° C. or higher, preferably 220 ° C. or higher, and 30 ° C. or higher than the polycondensation reaction temperature, Preferably, when the temperature reaches 35 ° C. or higher, the aromatic liquid crystalline polyester, which is the content of the reaction vessel, is recovered and solidified in a molten state, and then pulverized into particles having a particle size of 3 mm or less, The heat treatment is performed in an inert gas atmosphere at 200 ° C. to 310 ° C. in a solid state. The time for the heat treatment in the solid state is preferably 1 to 24 hours.

Embedded image (However, R ¹ represents a hydrogen atom, a formyl group, an acetyl group, a propionyl group or a benzoyl group, and R ² represents a hydrogen atom, a methyl group, an ethyl group, a propyl group, a benzyl group or a phenyl group.)

Embedded image (However, the definitions of R ¹ and R ² are the same as the respective definitions in formula (I). R in formulas (I) and (II)
¹ may be the same or different from each other, and R ² in the formula (I) and the formula (II) may be the same or different from each other. Further, the method for producing an aromatic liquid crystalline polyester of the present invention is characterized in that the above-obtained powdery aromatic liquid crystalline polyester is granulated while being heated and melted. The form of granulation is preferably a pellet.

In the formula (I) of the present invention, those in which the benzene nucleus is substituted with a halogen, an alkyl group or the like are also included. Examples of the compound represented by the above formula (I) include 4-hydroxybenzoic acid, 4-formoxybenzoic acid, 4-acetoxybenzoic acid, 4-propionyloxybenzoic acid, methyl 4-hydroxybenzoate, and 4-hydroxybenzoate Propyl acid, phenyl 4-hydroxybenzoate, benzyl 4-hydroxybenzoate, methyl 4-acetoxybenzoate, phenyl 4-acetoxybenzoate and the like, particularly 4-hydroxybenzoic acid and 4-hydroxybenzoic acid.
Acetoxybenzoic acid is preferred.

Further, examples of the compound represented by the above formula (I) include 3-chloro-4-hydroxybenzoic acid,
2-chloro-4-hydroxybenzoic acid, 2,3-dichloro-4-hydroxybenzoic acid, 3,5-dichloro-4-
A nuclear-substituted compound such as hydroxybenzoic acid, 2,5-dichloro-4-hydroxybenzoic acid, 3-bromo-4-hydroxybenzoic acid, and acetylated products thereof can be used in combination for the purpose of improving gas barrier properties.

In the formula (II) according to the present invention, a compound in which a naphthalene nucleus is substituted with a halogen, an alkyl group or the like is also included. Examples of the compound represented by the above formula (II) include 6-hydroxy-2-naphthoic acid,
Examples include acetoxy-2-naphthoic acid, methyl 6-hydroxy-2-naphthoate, phenyl 6-hydroxy-2-naphthoate, and methyl 6-acetoxy-2-naphthoate. acid,
6-acetoxy-2-naphthoic acid is preferred. Examples of the compound represented by the above formula (II) include 6-hydroxy-5-chloro-2-naphthoic acid, 6-hydroxy-7-chloro-2-naphthoic acid, 6-hydroxy-4,
Nuclear-substituted compounds such as 7-dichloro-2-naphthoic acid and acetylated products thereof can be used in combination for the purpose of improving gas barrier properties.

In the present invention, 3-hydroxybenzoic acid, 3-formoxybenzoic acid, 3-acetoxy acid are used within a range that does not seriously affect the physical properties and processability (film forming property) of the obtained aromatic liquid crystalline polyester. Benzoic acid, 3-propionyloxybenzoic acid, methyl 3-hydroxybenzoate,
Propyl 3-hydroxybenzoate, phenyl 3-hydroxybenzoate, benzyl 3-hydroxybenzoate, 3-
Methyl acetoxybenzoate, 4'-hydroxybiphenyl-4-carboxylic acid, 4'-acetoxybiphenyl-4
-Carboxylic acids and the like can be used in combination.

In producing the aromatic liquid crystalline polyester of the present invention, first, a mixture comprising the compounds represented by the above formulas (I) and (II) is subjected to a polycondensation reaction in a reaction vessel. The compound may be charged into the polymerization tank by a batch system or a batch system. When a compound having a phenolic hydroxyl group is used as the formula (I) or (II), a reaction (for example, an esterification reaction using an acid anhydride such as acetic anhydride) for converting the compound into a compound which is more easily polycondensed is carried out. Prior to the condensation reaction, it is preferable to carry out the polycondensation reaction after performing the reaction in a separate or the same reaction vessel as the one for performing the polycondensation reaction. When a compound having a phenolic hydroxyl group is used as the above formula (I) or (II), acetic anhydride is preferably used in an amount equal to or more than the equivalent of the phenolic hydroxyl group, more preferably 1.1 to 1.3 times equivalent. The acid anhydrides such as the above formulas (I) and (II)
It is more preferable that the mixture is charged into a reaction vessel together with a mixture of the compounds represented by the formula (II), and after the esterification reaction is performed, a polycondensation reaction is performed. At that time, the material of the acetylation reaction tank was
Corrosion-resistant materials such as titanium and Hastelloy B can be used. When the polyester requires a high color tone (L value), it is preferable to use a glass-lined SUS or other reaction tank.

The polycondensation reaction in the present invention can be carried out under an inert gas, for example, a nitrogen atmosphere at normal pressure, reduced pressure, or a combination thereof, but can be carried out under an inert gas atmosphere under normal pressure. preferable. The process is batch,
A continuous type or a combination thereof can be adopted. The temperature of the polycondensation reaction in the present invention is in the range of 270 to 350 ° C, preferably 280 to 330 ° C. If the temperature is lower than 270 ° C., the reaction progresses slowly, and if it exceeds 350 ° C., side reactions such as decomposition are likely to occur. When the reaction tank is divided into multiple stages or partitioned, the reaction temperature of the final portion is the polycondensation reaction temperature referred to in the present invention.

The time of the polycondensation reaction should be appropriately determined depending on the reaction conditions and the like.
Five hours is preferred. A multi-stage reaction temperature may be employed, and in some cases, an aromatic liquid crystalline polyester, which is a reaction product, can be extracted and recovered in a molten state during the reaction or immediately after reaching the maximum temperature.

The melt polycondensation reaction usually proceeds sufficiently without a catalyst, but if necessary, Ge, Sn,
Compounds such as oxides such as Ti, Sb, Co, and Mn, and acetates can also be used. When used for a film for food packaging, it may be necessary to remove a catalyst component or the like, and a non-catalyst is preferred.

As the shape of the reaction vessel, known ones can be used. In the case of a vertical reaction tank, multi-stage paddle blades, turbine blades, Monte blades, and double helical blades are preferable. In the case of a horizontal reaction tank, blades of various shapes perpendicular to one or two stirring axes, for example, A lens wing, a spectacle wing, a multi-circular flat wing, or the like is preferably provided. Further, the blade may be twisted to improve the stirring performance and the feed mechanism. Heating of the reaction tank is performed by a heating medium, gas, and electric heater.
For the purpose of uniform heating, it is preferable to heat the stirring shaft, blades, baffles, and the like.

In the method for producing an aromatic liquid crystalline polyester, the flow temperature of the aromatic liquid crystalline polyester obtained by the polycondensation reaction may be a temperature of 210 ° C. or higher and a temperature lower than the polycondensation reaction temperature by 30 ° C. or higher. Is important,
When the flow temperature of the obtained aromatic liquid crystalline polyester is 22
The temperature is preferably 0 ° C. or higher and 35 ° C. or lower than the polycondensation temperature. If the flow temperature is less than 210 ° C., the molecular weight of the aromatic liquid crystalline polyester is not sufficient, and there is a problem in processing and physical properties. Even if post-treatment such as solid phase polymerization is performed, fusion between aromatic liquid crystalline polyesters and a large amount of by-products occur, which is not economically preferable. If the fluidization temperature is close to the polycondensation reaction temperature, the viscosity of the polyester will increase, making it difficult to recover, and also worsening the stirring and mixing properties, which will affect the thermal stability of the polymer due to uneven heating. There is. Further, industrially, in a batch polymerization system, washing the polymerization tank increases the cost, so that continuous use of the polymerization tank is advantageous, and the conditions for melting and extracting are particularly important. As a method for cleaning the reaction kettle, JP-A-5-295
No. 92, JP-A-5-29593, and the washing method with glycols and / or amines.

When the aromatic liquid crystalline polyester is taken out in a molten state, it is preferably carried out in an inert gas atmosphere, for example, in a nitrogen atmosphere in view of the color tone of the obtained polymer. good. When the aromatic liquid crystalline polyester is taken out in a molten state, the polymerization tank is preferably placed under an inert gas atmosphere such as nitrogen or an inert gas atmosphere such as nitrogen, preferably 0.1 to ² kg / cm ² G,
More preferably, pressurization at 0.2 to 1 kg / cm ² G is preferable from the viewpoint of suppressing an increase in the flowing temperature of the polymer at the time of extraction.

As a mechanism for taking out the aromatic liquid crystalline polyester of the present invention in a molten state, a known extruder and a gear pump may be mentioned, but a simple valve may be used. The removed material usually solidifies after a while, and can be cut or crushed by a strand cutter or a sheet cutter according to the purpose. As a means for processing a large amount and in a short time, there is a method of cooling with a double belt cooler via a fixed amount supply device described in JP-A-6-256485.

The aromatic liquid crystalline polyester recovered in a molten state is subjected to solid-phase polymerization in order to remove unreacted raw materials and increase the molecular weight to increase physical properties. The obtained aromatic liquid crystalline polyester is pulverized with a known pulverizer, 3 mm or less, preferably 0.5 mm or less, more preferably 0.1 mm or less.
-0.4 mm average particle size (Rosin-Rammlar
It is preferable to carry out solid-phase polymerization in which particles (powder) of the above method are heat-treated in an inert gas atmosphere in a solid state.
If the average particle size exceeds 3 mm, the polymerization rate and the diffusion time of by-products generated as a result of the reaction of unreacted raw materials differ between the surface layer and the inside. Since it cannot be sufficiently removed, foaming or gas generation may be caused, which is not preferable.

The heating rate and the maximum processing temperature during the solid phase polymerization are as follows:
It is necessary to select so as not to fuse the aromatic liquid crystalline polyester particles. If fusion occurs, the surface area will decrease,
The polycondensation reaction and the removal of low boiling components are undesirably slow. The maximum treatment temperature of the solid-state polymerization is in the range of 200 to 310 ° C. without fusion, and more preferably 230 to 310 ° C.
It is effective to perform the treatment in an inert gas atmosphere at a temperature of 300 ° C. At temperatures below 200 ° C., the reaction is slow,
Processing time is uneconomical, and if it exceeds 310 ° C.,
Since the powder particles are fused or melted, the solid state cannot be maintained, which is not preferable.

As the solid-phase polymerization apparatus, known dryers, reactors, mixers, electric furnaces and the like can be used, but from the above-mentioned point, a gas-flow-type apparatus having a high airtightness is preferable. Inert gases include nitrogen, helium, argon,
Those selected from carbon dioxide are preferred, and nitrogen is more preferred. The flow rate of the inert gas is determined in consideration of the volume of the solid-state polymerization device, the particle size of the powder, the filling state, and the like.
Solid phase polymerization vessel 1 m ³ per 2m ³ / hr~8m ³ / hr, more preferably 3m ³ / hr~6m ³ / hr. When the flow rate of the inert gas is less than 2 m ³ / hr, the polymerization rate is low,
If it exceeds m ³ / hr, the powder may be scattered.

The aromatic liquid crystalline polyester obtained by the production method of the present invention comprises the following repeating unit (A) in an amount of 20 to 80 mol% of the entire repeating unit, and the repeating unit (B) of 8
0 to 20 mol%, the logarithmic viscosity is 4.0 dl / g or more, the flow temperature is 320 ° C. or less,
2. Melt tension measured at a temperature higher than 5 ° C.
Aromatic liquid crystalline polyester showing 0 g or more, exhibiting optical anisotropy (liquid crystal properties) when melted, and having excellent melt moldability, chemical resistance, and mechanical properties. The aromatic liquid crystalline polyester of the present invention is preferably an aromatic liquid crystalline polyester comprising the following repeating unit (A) 25 to 75 mol% and the repeating unit (B) 75 to 25 mol%.

Embedded image

Embedded image

In the aromatic liquid crystalline polyester of the present invention, the proportion of the repeating unit (A) is 80 mol%.
When the ratio exceeds, there are many cases where there is a portion which is not melted by heating, so that the melt processability is remarkably deteriorated, and even if less than 20 mol%, the repeating unit (B) exceeds 80 mol%,
Since the processing temperature exceeds 320 ° C., it is not preferable in view of workability. Within the above range, molding (film formation) at a lower temperature becomes possible, and in particular, it becomes possible to obtain a thin film having excellent thickness of 20 μm or less in oxygen barrier property and water vapor barrier property. Shows well-balanced physical properties and workability. In the conventional method, for example, one-stage polymerization under reduced pressure, there are problems such as adhesion to piping at the time of removal and thickening at the time of retention, so that it may be difficult to take out with a sufficient molecular weight suitable for film formation. It is considered difficult to set the melt tension to a desired value. In the production method of the present invention, by using melt polycondensation (pre-polymerization) and solid-phase polymerization of the pulverized powder after the melt is withdrawn, it is possible to stably increase the melt tension to a desired melt tension. preferable.

The aromatic liquid crystalline polyester of the present invention has a logarithmic viscosity (ηinh) defined by the following formula of 4.0 dl / g.
Or more, preferably 6.0 dl / g or more, more preferably 8.0 dl / g or more, and even more preferably 10.0 d / g or more.
1 / g or more is preferable in that high melt tension is provided. Further, ηinh is preferably 20 dl / g or less, more preferably 15 dl / g or less from the viewpoint of moldability and the like. . If ηinh is less than 4.0 dl / g,
The melt tension is small and there is a problem in film forming properties, or there is a problem in mechanical strength.

Η inh = (ln (η rel)) / C (where η rel is referred to as relative viscosity and is the ratio of the time for polymer solution and solvent to fall between fixed marks in the capillary (polymer solution / solvent) C is the concentration of the polymer solution and the unit is g / dl In the present invention, the solvent is 3,5-bis (trifluoromethyl)
It is a value measured with an Ubbelohde viscometer using phenol at a polymer concentration of 0.1 g / dl and a temperature of 60 ° C. )

The aromatic liquid crystalline polyester of the present invention has a flow temperature of 320 ° C. or lower, preferably 230 to 295 ° C.
More preferably, it is 240 to 290 ° C. If the flow temperature exceeds 320 ° C., the processing temperature may exceed 350 ° C., which is not preferable. Here, the flow temperature (hereinafter “F
T ". ) Means a capillary type rheometer (for example, Shimadzu's advanced type flow tester CFT)
-500 type), and heated and melted at a heating rate of 4 ° C./min under a load of 100 kgf / cm ² ,
When extruded from a nozzle having an inner diameter of 1 mm and a length of 10 mm, the temperature (° C.) at which the melt viscosity shows 48,000 poise.

The aromatic liquid crystalline polyester of the present invention has a melt tension of 3.0 g measured at a temperature higher than the flow temperature by 25 ° C. or more under the conditions of a capillary inner diameter of 2.1 mm, a length of 8 mm, and a piston speed of 5 mm / min. The above is indicated, preferably 6.0 g or more, more preferably 12.0 g or more. Although it depends on the composition of the aromatic liquid crystalline polyester, when the MT is less than 3.0 g, the stable film formation temperature range in inflation film formation often becomes narrow, and the frost line often becomes unstable. MT is preferably 30 g or less, more preferably 25 g or less, and from the viewpoint of film forming property, it is preferable that the temperature dependency of MT is small.

The aromatic liquid crystalline polyester of the present invention preferably has a shear rate of 100 sec ^-1 or 1 at a temperature (flow temperature) at which an anisotropic molten phase starts to form.
The ^value of the ratio (viscosity 2 / viscosity 1) between the melt viscosity (viscosity 1) measured at 000 sec ^-1 and the melt viscosity (viscosity 2) measured at the same shear rate as viscosity 1 at a temperature 20 ° C. higher than the flow temperature is 1 , 0.20 to 0.80, preferably 0.25
~ 0.70, preferably showing a value larger than that of the conventional aromatic liquid crystalline polyester (0.16 or less). The temperature dependence of the melt viscosity of the aromatic liquid crystalline polyester is small, and the molding stability during processing tends to be improved.

The aromatic liquid crystalline polyester used in the present invention may be used in a usual molding process in the form of pellets or pellets obtained by heating and melting into pellets using a twin-screw extruder or the like (granulated pellets). However, more preferred are granulated pellets. The flow temperature (FT1) of the pellets of the aromatic liquid crystalline polyester of the present invention after granulation is lower than the flow temperature (FT0) at the stage of the powder (sometimes abbreviated as advanced polymer) after solid-phase polymerization. Show the trend. This tendency is greatly reduced as compared with the conventional aromatic liquid crystalline polyester using the solid phase polymerization method. This difference is considered to be caused by a difference in crystallinity due to a difference in solid-state polymerization conditions. In order to lower the molding temperature of the aromatic liquid crystalline polyester and improve molding processability, FT1 is preferably lower than [(FT0) -5] ° C, and lower than [(FT0) -10] ° C. Is more preferred.

As a method for granulating the aromatic liquid crystalline polyester into pellets while melting by heating, a known method can be used. There is also a method in which a molten state is supplied from a polymerization tank to a parallel roller with grooves, shaped into a strand shape (string shape), and cut by a strand cutter or the like. As a method for producing pellets by granulating an aromatic liquid crystalline polyester powder, melt kneading using a commonly used single-screw or twin-screw extruder, air-cooled or water-cooled as necessary, is usually used. Form into pellets with a pelletizer (strand cutter). A general-purpose kneader can be used for the purpose of melting uniformity and shaping.
Those having a large / D are preferable from the viewpoint of uniform melting.
At the time of melt-kneading, the cylinder set temperature (die head temperature) of the kneading device is preferably in the range of 200 to 350 ° C, more preferably 230 to 330 ° C, and still more preferably 240 to 320 ° C.

The aromatic liquid crystalline polyester used in the present invention may optionally contain an inorganic filler. Such inorganic fillers include calcium carbonate,
Examples include talc, clay, silica, magnesium carbonate, barium sulfate, titanium oxide, alumina, montmorillonite, gypsum, glass flake, glass fiber, carbon fiber, alumina fiber, silica alumina fiber, aluminum borate whisker, potassium titanate fiber and the like. You. These inorganic fillers can be used within a range that does not significantly impair the transparency and mechanical strength of the film.

The aromatic liquid crystalline polyester used in the present invention may further contain, if necessary, an organic filler, an antioxidant, a heat stabilizer, a light stabilizer, a flame retardant, a lubricant, an antistatic agent,
Inorganic or organic colorant, rust inhibitor, cross-linking agent, foaming agent,
Various additives such as a fluorescent agent, a surface smoothing agent, a surface gloss improving agent, or a mold release improving agent such as a fluororesin can be added during the manufacturing process or in the subsequent processing process.

The method for forming a film comprising the aromatic liquid crystalline polyester of the present invention is not particularly limited, and it can be carried out by a known method. For example, a film can be obtained by an inflation film forming method in which a molten resin is extruded from a T die and wound up, or a molten resin is extruded into a cylindrical shape from an extruder provided with an annular die, cooled and wound up. A film obtained by further uniaxially stretching a sheet obtained by an injection molding method or an extrusion method can also be obtained.

Among these, a preferred inflation film forming method will be described as a method of forming (film forming) the aromatic liquid crystalline polyester film. That is, the aromatic liquid crystalline polyester is supplied to a melt-kneading extruder equipped with a die having an annular slit, and is set at a cylinder set temperature of preferably 20.
The mixture is melt-kneaded at 0 to 320 ° C, more preferably 210 to 310 ° C, particularly preferably 220 to 310 ° C, and the extruder extrudes the cylindrical film upward or downward from the annular slit. The interval between the annular slits is usually 0.25 to
2 mm, preferably 0.5 to 1.5 mm, more preferably 0.7 to 1.2 mm, and the diameter of the annular slit is
Usually 20 to 1000 mm, preferably 25 to 600 mm
It is.

The melt-extruded cylindrical molten resin film is drafted in the longitudinal direction (MD), and air or an inert gas, for example, nitrogen gas, is blown from the inside of the cylindrical film so as to extend in the longitudinal direction. The film is expanded and stretched in the transverse direction (MD) at right angles.

In the blown film formation of the film comprising the aromatic liquid crystalline polyester of the present invention, the preferred TD stretching ratio, that is, the blow ratio is from 1.5 to 15, more preferably from 2.5 to 15. Also, preferred M
The D stretching ratio, that is, the draw ratio is from 1.5 to 60, and more preferably from 2.5 to 50. Here, the blow ratio is determined by (diameter of cylindrical film) / (diameter of die), and the draw ratio is determined by (area of annular slit) / (cross-sectional area of film). If the setting conditions at the time of inflation film formation are out of the above range, it is difficult to obtain an aromatic liquid crystalline polyester film having a uniform thickness and a strength without wrinkles.

The expanded film is usually cooled around its circumference with air or an inert gas such as nitrogen gas and then pulled through a nip roll. In inflation film formation, conditions can be selected according to the composition of the aromatic liquid crystalline polyester such that the cylindrical molten film expands to a uniform thickness and a smooth surface.

The thickness of the film layer made of the aromatic liquid crystalline polyester of the present invention is not particularly limited, but is preferably 1 to 500 μm, more preferably 5 to 200 μm, and still more preferably 5 to 50 μm.

[0044]

The present invention will be described in detail with reference to the following examples, which should not be construed as limiting the scope of the present invention. In addition, each physical property was measured by the method shown below.

[Measurement Method of Physical Properties] Fluid temperature (FT): an index indicating the melt fluidity, which is measured by a capillary rheometer (manufactured by Shimadzu Corporation, Koka type flow tester CFT500). A sample resin (approximately 2 g) measured and heated and melted at a heating rate of 4 ° C./min, with an inner diameter of 1 m under a load of 100 kg / cm ²
m, when extruded from a nozzle having a length of 10 mm, the melt viscosity was expressed as a temperature (° C.) at which 48,000 poise (corresponding to 4800 Pa · S) was exhibited.

Melt viscosity: Using a Capillograph 1B (manufactured by Toyo Seiki Seisakusho), the inner diameter of the capillary was 0.5
A sample having a length of 10 mm and a length of 10 mm was charged with about 10 g of a sample, and a predetermined shear rate (100 sec.) was obtained at a predetermined temperature.
The melt viscosity was measured at c ⁻¹ , 1000 sec ⁻¹ ).

Melt tension (melt tension): Using a Capillograph 1B type (manufactured by Toyo Seiki Seisaku-sho, Ltd.), about 1 sample was used.
0 g, the inner diameter of the capillary was 2.095 mm, the length was 8.0 mm, and the extrusion speed of the piston was 5.0 mm /
The sample was taken up in a thread shape while being automatically accelerated by a variable speed winder, and the tension (g) at break was measured.

Optical anisotropy: The optical anisotropy of the sample resin in the molten state was determined by measuring the particle size of 25 placed on the heating stage.
The sample resin powder having a particle size of 0 μm or less was heated under polarized light at a rate of 25 ° C./min, and visually observed or the amount of transmitted light was recorded on an XY recorder.

Oxygen permeability: OX-TRAN 2/20 type (Modern) according to JIS K7126 B method
(Manufactured by Control Co., Ltd.) at a temperature of 23.5 ° C. and a relative humidity of 64%. Unit is cc / m ² · 24h
r · atm.

Water vapor permeability: Measured at a temperature of 40 ° C. and a relative humidity of 90% according to JIS Z0208 (cup method). The unit is g / m ² · 24 hr · atm.
The oxygen gas transmission rate and the water vapor transmission rate were determined by setting the film thickness to 25.
It was calculated by converting to μm.

Example 1 ((A) / (B) = 73/27 in the repeating structural unit)
(Mol%). (1) Melt polymerization A three-liter four-tube having a Dimroth cooling tube, a nitrogen-introducing tube, a G-type connecting tube equipped with a thermocouple for measuring the internal temperature, and a squirrel-type stirring blade, and a thermocouple also provided on the outside of the flask. Using a mouth-separable flask, 1207.3 g (8.74 mol) of 4-hydroxybenzoic acid, 608.4 g (3.23 mol) of 6-hydroxy-2-naphthoic acid, and 1345 g of acetic anhydride ( 13.2 mol), and the outside temperature of the flask was raised to 150 with a mantle heater under a nitrogen stream.
C., and the acetylation reaction was performed under reflux for about 3 hours while stirring at 200 rpm. Subsequent to the acetylation reaction, the temperature was raised at 1 ° C./min and maintained at 310 ° C. to perform melt polycondensation. During this time, acetic acid produced as a by-product of the polycondensation reaction was continuously distilled off. Sampling was performed 30 minutes after the temperature reached 310 ° C. during the polymerization, and the flow temperature was measured. After 35 minutes, the stirring was stopped and the polymer could be easily removed in a molten state. There was almost no adhesion to the polymerization tank and the stirring blade. The obtained polyester solidified after a while. The yield was 1565 g (97.8% of the theoretical yield). The obtained polyester is 3
After sizing to a size of about 5 cm square, using a pulverizer, pulverizing to an average particle size of 1 mm or less, and measuring the flow temperature (FT), it was 239 ° C. This polymer (prepolymer) exhibited optical anisotropy when melted.

(2) Solid-phase polymerization This prepolymer was placed in an aluminum tray, charged in a nitrogen atmosphere furnace, and heated from room temperature to 180 ° C. under a nitrogen atmosphere.
After heating for 2 hours at the same temperature, the temperature was further increased to 270 ° C. over about 7.5 hours, maintained at the same temperature for 5 hours, allowed to cool, and then taken out. A group III liquid crystalline polyester (advanced polymer) powder was obtained. The weight loss here was 1.5%.

(3) Granulation The obtained advanced polymer was used as a P.I.
With a CM-30 twin screw extruder, the die head temperature is 300 ° C.
And melt kneading was performed at a screw rotation speed of 80 rpm to obtain aromatic liquid crystalline polyester pellets having an FT of 264 ° C. 295 ° C of this resin pellet (FT + 31
° C) is 7.7 g and 6
The logarithmic viscosity (ηinh) measured at 0 ° C. is 5.5 dl /
g. The melt viscosity is shown in Table 1.

Example 2 ((A) / (B) = 73/27 in the repeating structural unit)
(Mol%). (1) Melt polymerization In the same manner as in Example 1 (1), 1207.3 g (8.74 mol) of 4-hydroxybenzoic acid, 6-hydroxy-2
-Charged 608.4 g (3.23 mol) of naphthoic acid and 1345 g (13.2 mol) of acetic anhydride, and after acetylation (150 ° C, about 3 hours under reflux), the temperature was raised at 1 ° C / min to 310 ° C. While maintaining the temperature, the melt polymerization was carried out while continuously distilling off acetic acid as a by-product. The stirring was stopped 15 minutes after the temperature reached 310 ° C., and the polymer was easily removed in a molten state. There was almost no adhesion to the polymerization tank and the stirring blade. The obtained polyester solidified after a while. The yield was 1570 g (98.1% of the theoretical yield). After the obtained polyester is sized to a size of about 3 to 5 cm square, crushed using a crusher to an average particle size of 1 mm or less, the flow temperature (F)
T) was 210 ° C. when measured. This polymer (prepolymer) exhibited optical anisotropy when melted.

(2) Solid-phase polymerization Solid-phase polymerization was carried out under the same conditions as in Example 1 (2), allowed to cool, and taken out to obtain a powder of an aromatic liquid crystalline polyester (advanced polymer) having an FT of 288 ° C. . Here, the weight loss was 3.3%.

(3) Granulation Using the same apparatus as in Example 1 (3), the die head temperature was set at 300 ° C., and the mixture was melt-kneaded at a screw rotation speed of 80 rpm to obtain an aromatic liquid crystal having an FT of 265 ° C. Polyester pellets were obtained. 305 ° C (F
(T + 40 ° C.), the melt tension was 9.1 g, and the logarithmic viscosity (ηinh) measured at 60 ° C. was 5.
It was 6 dl / g. The melt viscosity is shown in Table 1.

Example 3 ((A) / (B) = 73/27 in the repeating structural unit)
(Mol%). (1) Melt polymerization In the same manner as in Example 1 (1), 1207.3 g (8.74 mol) of 4-hydroxybenzoic acid, 6-hydroxy-2
-Charged 608.4 g (3.23 mol) of naphthoic acid and 1345 g (13.2 mol) of acetic anhydride, and after acetylation (150 ° C, about 3 hours under reflux), the temperature was raised at 1 ° C / min to 310 ° C. , And melt polymerization was carried out while acetic acid produced as a by-product was continuously distilled off. Sampling was performed 60 minutes after the temperature reached 310 ° C., and the flow temperature was measured. After 90 minutes, the stirring was stopped, and the polymer could be easily removed in a molten state. There was almost no adhesion to the polymerization tank and the stirring blade. The obtained polyester solidified after a while. The yield was 1573 g (98.3% of the theoretical yield). The same operation was repeated 7 times, and the obtained polyester was reduced to a size of about 3 to 5 cm square, then pulverized to an average particle diameter of 1 mm or less using a pulverizer, and the flow temperature (FT) was measured. 248 ° C. This polymer (prepolymer) exhibited optical anisotropy when melted.

(2) Solid-phase polymerization The prepolymer was placed in an aluminum tray, and the solid-phase polymerization conditions were raised from room temperature to 180 ° C. in 3 hours, and maintained at the same temperature for 2 hours. 280 ° C over 3 hours
Up to 5 hours at the same temperature "
Solid phase polymerization was carried out in the same manner as in Example 1 (2), and after cooling, the product was taken out to obtain a powder of an aromatic liquid crystalline polyester (advanced polymer) having an FT of 357 ° C. The weight loss here was 1.2%.

(3) Granulation The obtained advanced polymer was used in the same apparatus as in Example 1 (3), and the die head temperature was set to 340 ° C.
Melt kneading at a screw rotation speed of 100 rpm, FT
Was 277 ° C. to obtain aromatic liquid crystalline polyester pellets. The melt tension of the resin pellet at 307 ° C. (FT + 30 ° C.) was 22.7 g, and the logarithmic viscosity (ηinh) measured at 60 ° C. was 11.1 dl / g. The melt viscosity is shown in Table 1.

(4) Inflation film formation A 30 mmφ twin screw extruder was installed on the obtained aromatic liquid crystalline polyester pellets in a Labo Plast Mill (manufactured by Toyo Seiki Seisaku-sho, Ltd.).
A 75 mm inflation die was attached, and a film was formed at a cylinder set temperature of 230 to 255 ° C, a screw rotation speed of the cylinder of 80, a die head set temperature of 255 ° C, and a take-up speed of 30 m / min to obtain a film with a folded width of 120 mm. The bubbles were stable, the film thickness was 4 to 9 μm, and the film appearance was relatively good. Pickup speed 10m
The die head set temperature at which a film can be formed at a rate of at least
285 ° C.

Example 4 ((A) / (B) = 30/70 in the repeating structural unit)
(Mol%). (1) Melt polymerization In the same manner as in Example 1 (1), 428.8 g (3.10 mol) of 4-hydroxybenzoic acid, 6-hydroxy-2-
1359.7 g (7.20 mol) of naphthoic acid and 1159.7 g (11.4 mol) of acetic anhydride were charged, and after acetylation (150 ° C., about 3 hours under reflux), the temperature was raised at 1 ° C./min to 320 ° C. , And melt polymerization was carried out while acetic acid produced as a by-product was continuously distilled off. The stirring was stopped 45 minutes after the holding at 320 ° C., and the polymer was easily removed in a molten state. This polymer had an FT of 247 ° C. and exhibited optical anisotropy when melted. The yield of the obtained polyester is 1
557 g (97.2% of the theoretical yield).

Solid-state polymerization The prepolymer was placed in an aluminum tray, and the solid-state polymerization conditions were changed from “room temperature to 208 ° C. over 3 hours.
The solid phase polymerization was carried out in the same manner as in Example 1 (2) except that the temperature was raised to 260 ° C. over 40 minutes and the temperature was maintained for 5 hours, and an aromatic liquid crystalline polyester (FT) having a powder FT of 281 ° C. ) Got. The weight loss here is 1.
It was 0%.

(3) Granulation The obtained advanced polymer was melt-kneaded using the same apparatus as in Example 1 (3), the die head temperature was set to 310 ° C., and the screw rotation speed was 150 rpm. An aromatic liquid crystalline polyester pellet having an FT of 260 ° C. was obtained. 290 ° C. (FT + 30)
° C) is 4.7 g and 6
The logarithmic viscosity (ηinh) measured at 0 ° C. is 4.4 dl /
g. The melt viscosity is shown in Table 1.

Example 5 ((A) / (B) = 60/40 in the repeating structural unit)
(Mol%). (1) Melt polymerization In the same manner as in Example 4 (1), 947.0 g (6.9 mol) of 4-hydroxybenzoic acid, 860.3 g (4.6 mol) of 6-hydroxy-2-naphthoic acid and 1283.7 g (12.6 mol) of acetic anhydride was charged, acetylated (150 ° C., about 3 hours under reflux), and then heated at 1 ° C./min.
The mixture was kept at 20 ° C., and melt polymerization was carried out while acetic acid produced as a by-product was continuously distilled off. The stirring was stopped 45 minutes after the holding at 320 ° C., and the polymer was easily removed in a molten state. This polymer had an FT of 216 ° C. and exhibited optical anisotropy when melted. The yield of the obtained polyester was 1,563 g.
(97.7% of theoretical yield).

(2) Solid-phase polymerization This prepolymer was placed in an aluminum tray, and the solid-phase polymerization conditions were changed from “room temperature to 190 ° C. over 3 hours.
The solid phase polymerization was carried out in the same manner as in Example 1 (2) except that the temperature was raised to 240 ° C. over 20 minutes and the temperature was maintained for 5 hours. ) Got. The weight loss here is 0.
9%.

(3) Granulation The obtained advanced polymer was melt-kneaded using the same apparatus as in Example 1 (3), the die head temperature was set to 280 ° C., and the screw rotation speed was 150 rpm. An aromatic liquid crystalline polyester pellet having an FT of 230 ° C. was obtained. 260 ° C. (FT + 30
° C) is 3.0 g and 6
The logarithmic viscosity (ηinh) measured at 0 ° C. is 4.9 dl /
g. The melt viscosity is shown in Table 1.

Comparative Example 1 (1) Vacuum polymerization In the same manner as in Example 1, (A) /
(B) 1208.9 g (8.76 mol) of 4-hydroxybenzoic acid corresponding to a molar ratio of 73/27 (mol%) 6-
609.1 g (3.24 mol) of hydroxy-2-naphthoic acid and 1346.4 g (13.21 mol) of acetic anhydride were charged into a polymerization tank equipped with comb-shaped stirring blades, and stirred at 150 ° C. under a nitrogen gas atmosphere. Acetylation reaction was carried out under reflux for about 3 hours. Following the acetylation reaction, the temperature was raised at a rate of 1 ° C./min while the acetic acid produced as a by-product was continuously distilled off, and the external temperature of the polymerization tank was maintained at 330 ° C. to perform melt polycondensation. Thereafter, while maintaining the external temperature of the polymerization tank at 330 ° C., a pressure reducing operation was performed to the ultimate pressure over 40 minutes, and after maintaining at 2 torr for 5 minutes, stirring was stopped to remove the polymer.
Adhesion of the polymer to the polymerization tank and the stirring blade was observed. The yield was 1551 g (97.1% of the theoretical yield). An attempt was made to pulverize the obtained polyester using a crusher. However, the pulverization speed was lower than that in Example 1 due to fiberization. When the flow temperature (FT) of the material having passed through the filter having an average particle size of 3 mm or less was measured,
1 ° C.

(2) Granulation The obtained polymer was set at a die head temperature of 260 ° C. and a screw rotation speed of 80 in the same manner as in Example 1 (3).
Melt kneading was performed at rpm to obtain an aromatic liquid crystalline polyester pellet having an FT of 263 ° C. The melt tension of this resin pellet at 305 ° C. (FT + 42 ° C.) was 2.8 g, and the logarithmic viscosity (ηi) measured at 60 ° C.
nh) was 5.5 dl / g. The melt viscosity is shown in Table 1.

[0069]

[Table 1]

[0070]

According to the method for producing an aromatic liquid crystalline polyester of the present invention, a high molecular weight liquid crystalline polyester can be obtained more stably than a known production method in which polycondensation is performed under reduced pressure after the polymerization. The aromatic liquid crystalline polyester obtained by this production method has a low temperature dependence of the melt viscosity, and tends to have a wide processing temperature range. With the same composition, it is possible to increase the melt tension by increasing the molecular weight, and film forming processing It is possible to produce a material having a melt tension suitable for the above. The film made of the wholly aromatic liquid crystalline polyester has sufficient heat resistance as a packaging material, has low-temperature processability, is a film excellent in gas barrier properties, has a good film appearance, and is excellent in food packaging and chemicals. It can be used as a resin material for films for various packaging uses such as packaging, cosmetics packaging and electronic material packaging, a resin material for blows for various container uses, and a material for injection molding.

 ──────────────────────────────────────────────────の Continuing from the front page (72) Inventor Shino Moriyama 6 Kitahara, Tsukuba, Ibaraki Prefecture F-term (reference) 4J029 AA04 AB01 AB04 AC02 AD01 AD10 AE04 EB05A HA01 HA05 HB01 HB02 HB03A HB04A KB02 KD02 KE02 KE05 KE05

Claims (6)

[Claims] (1) A compound represented by the following formula (I):
20 mol% of a compound represented by the following formula (II):
~ 80 mol% into the reaction vessel, 270-350
When the flow temperature of the produced aromatic liquid crystalline polyester reaches 210 ° C. or more and 30 ° C. or more lower than the polycondensation reaction temperature, the aromatic After the liquid crystalline polyester is recovered and solidified in a molten state, it is pulverized into particles having a particle size of 3 mm or less,
200 ° C to 310 ° C under an inert gas atmosphere in the solid state
A method for producing an aromatic liquid crystalline polyester, wherein the heat treatment is performed by a heat treatment. Embedded image (However, R ¹ represents a hydrogen atom, a formyl group, an acetyl group, a propionyl group or a benzoyl group, and R ² represents a hydrogen atom, a methyl group, an ethyl group, a propyl group, a benzyl group or a phenyl group.) ] (However, the definitions of R ¹ and R ² are the same as the respective definitions in formula (I). R in formulas (I) and (II)
¹ may be the same or different from each other, and R ² in the formula (I) and the formula (II) may be the same or different from each other. Here, the flow temperature is measured by a capillary rheometer, and the resin heated and melted at a heating rate of 4 ° C./min, under a load of 100 kgf / cm ² , an inner diameter of 1 mm and a length of 10 mm
mm when extruded from a nozzle having a melt viscosity of 48,
A temperature (° C.) indicating 000 poise. 2. A method for producing an aromatic liquid crystalline polyester, comprising subjecting the aromatic liquid crystalline polyester obtained by the heat treatment according to claim 1 to melting by heating and granulating. (3) using 4-hydroxybenzoic acid as the formula (I) and 6-hydroxy-2-naphthoic acid as the formula (II), followed by acetylation with acetic anhydride in an amount equal to or more than the equivalent of the phenolic hydroxyl group; The method for producing an aromatic liquid crystalline polyester according to claim 1 or 2, wherein the polycondensation reaction is carried out. 4. A glass-lined reaction vessel (acetyl) using 4-hydroxybenzoic acid as the formula (I) and 6-hydroxy-2-naphthoic acid as the formula (II) when acetylating with acetic anhydride. The method for producing an aromatic liquid crystalline polyester according to claim 1 or 2, wherein a polycondensation reaction is carried out after the reaction is carried out using a polymerization tank) and transferred to the polymerization tank. 5. The method according to claim 1, wherein the following repeating unit (A) is used in an amount of 75 to 25 mol% of the entire repeating unit, and the repeating unit (B) is used in an amount of 25 to 25 mol%.
７５75 mol%, the logarithmic viscosity is 4.0 dl / g or more, the fluid temperature is 320 ° C. or less, and the fluid temperature is 25
3. Melt tension measured at a temperature higher by at least
g of an aromatic liquid crystalline polyester. Embedded image Embedded image 6. A shear rate of 100 sec ^-1 or 1000 sec at a flow temperature of an aromatic liquid crystalline polyester produced by the method according to claim 1.
^From the melt viscosity (viscosity 1) measured at ^-1 and the flow temperature
The value of the ratio (viscosity 2 / viscosity 1) of the viscosity 1 and the melt viscosity (viscosity 2) measured at the same shear rate at a high temperature is as follows:
An aromatic liquid crystalline polyester having a ratio of 0.20 to 0.80.