JP3175367B2 - Liquid crystalline polyester with improved homogeneity - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention only provides molded articles which are obtained only by melt polymerization, have excellent melt fluidity and optical anisotropy, and have excellent mechanical properties by ordinary molding methods. Rather, it relates to a liquid crystalline polyester having excellent melt spinnability and improved homogeneity.

[0002]

2. Description of the Related Art In recent years, there has been an increasing demand for higher performance of plastics, and a number of polymers having various novel functions have been developed. Among them, optically anisotropic liquid crystal polymers have excellent mechanical properties. (JP-A-51-8395, JP-A-49-7239)
No. 3).

[0003]

As the above liquid crystal polymer, for example, a liquid crystal polymer obtained by copolymerizing p-hydroxybenzoic acid with polyethylene terephthalate is known (JP-A-49-72393). However, this polymer has the disadvantage of poor mechanical properties, and it has been found that satisfactory injection molded articles cannot be obtained from this polymer. Means for improving the flowability of such a polymer, improving the melt moldability, and further improving the mechanical properties include, for example, JP-A-63-30523 and JP-A-4-305.
As described in JP 136027, a method of copolymerizing p-hydroxybenzoic acid, an aromatic dicarboxylic acid and an aromatic diol with polyethylene terephthalate has been proposed. It was found that properties and melt moldability were significantly improved over the polymers. However, it has been found that this liquid crystalline polyester is not always sufficient in terms of melt spinnability.

Accordingly, the present invention solves the above-mentioned problems and provides not only a molded article having excellent melt fluidity and optical anisotropy and excellent mechanical properties by a usual molding method, but also an excellent molded article. An object of the present invention is to obtain a liquid crystalline polyester having melt spinnability and improved homogeneity.

[0005]

That SUMMARY OF THE INVENTION The present invention has the following structural units (I), consists of (II), (III), (IV), structural units
The sum of the positions (I) and (II) is the sum of the structural units (I), (II) and (I
60 to 80 mol% based on the total amount of the structural units (III)
Is 20 to 40 of the total of the structural units (I), (II) and (III).
Mol%, which is the ratio of the structural unit (I) to the structural unit (II).
Liquid crystal having a ratio [(I) / (II)] of 78/22 to 93/7
The melting point (Tm, ° C) satisfies the formula (1), and the melting point width determined by differential calorimetry is 30 ° C.
The present invention provides a liquid crystalline polyester having improved homogeneity, characterized in that the following logarithmic viscosity is 1.0 to 3.0 dl / g.

[0006]

Embedded image (Where R ₁ is

Embedded image R ₂ represents one or more groups selected from

Embedded image Represents one or more groups selected from In the formula, X represents a hydrogen atom or a chlorine atom, and the structural units (II) and (III)
The sum and the structural units (IV) are substantially equimolar).

[0007] ^{-10 <Tm-0.0769x 2 + 8.20x} -401.5 <10 ... (1) ( provided that (1) the structural unit of x structural units of formula (III)
The ratio (mol%) to the total of (I), (II) and (III ) is shown).

The structural unit (I) is a structural unit of a polyester formed from p-hydroxybenzoic acid, and the structural unit (II) is 4,4'-dihydroxybiphenyl, 3,3
', 5,5'-Tetramethyl-4,4'-dihydroxybiphenyl, hydroquinone, t-butylhydroquinone, phenylhydroquinone, 2,6-dihydroxynaphthalene, 2,7-dihydroxynaphthalene, 2,2-
Bis (4-hydroxyphenyl) propane and 4,4
The structural unit generated from an aromatic dihydroxy compound selected from '-dihydroxydiphenyl ether, the structural unit (III) is a structural unit generated from ethylene glycol, and the structural unit (IV) is terephthalic acid, isophthalic acid,
4'-diphenyldicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 1,2-bis (phenoxy) ethane-4,
4'-dicarboxylic acid, 1,2-bis (2-chlorophenoxy) ethane-4,4'-dicarboxylic acid and 4,4 '
And structural units formed from aromatic dicarboxylic acids selected from -diphenyl ether dicarboxylic acid. Of these, R ₁ is

Embedded image And R ₂ is

Embedded image Is particularly preferred.

The above structural units (I), (II), (III) and (I)
Copolymerization amount of V) may be in terms of liquidity is the following proportions
Is necessary .

[0010] The sum of the structural units (I) and (II) the structure
60 to 80 based on the sum of the units (I), (II) and (III)
Mol% range . The structural unit (III) is the structural unit
20 to 40 mol% of the total of (I), (II) and (III)
It is an enclosure . In addition, the structural unit (I) corresponds to the structural unit (II).
The molar ratio [(I) / (II)] is 78/22 to 93/7 .
The structural unit (IV) is substantially equimolar to the sum of the structural units (II) and (III) .

In addition to the components constituting the above structural units (I) to (IV), aromatic dicarboxylic acids such as 3,3'-diphenyldicarboxylic acid and 2,2'-diphenyldicarboxylic acid, adipic acid, azelaic acid, sebacine Acid, aliphatic dicarboxylic acid such as dodecanedioic acid, alicyclic dicarboxylic acid such as hexahydroterephthalic acid, chlorohydroquinone, methylhydroquinone, 4,4′-dihydroxydiphenylsulfone, 4,4′-dihydroxydiphenylsulfide, 4, Aromatic diols such as 4'-dihydroxybenzophenone, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, 1,4-cyclohexanediol, aliphatic and alicyclic such as 1,4-cyclohexanedimethanol Formula diol and m-hydroxybenzoic acid, 2,6-hydro Aromatic hydroxycarboxylic acid and p- aminophenol such Shinafutoe acid, p-
Aminobenzoic acid and the like can be further copolymerized in a small proportion that does not impair the purpose of the present invention.

The method for producing the liquid crystalline polyester of the present invention is not particularly limited, and can be produced according to a known polyester polycondensation method.

For example, the following production method is preferably mentioned.

(1) p-acetoxybenzoic acid, diacylated aromatic dihydroxy compounds such as 4,4'-diacetoxybiphenyl and diacetoxybenzene, aromatic dicarboxylic acids such as terephthalic acid, and polyethylene terephthalate And a bis (β-hydroxyethyl) ester of an aromatic dicarboxylic acid such as a polyester polymer, oligomer or bis (β-hydroxyethyl) terephthalate by a deacetic acid polycondensation reaction.

(2) p-hydroxybenzoic acid and aromatic dihydroxy compounds such as 4,4'-dihydroxybiphenyl and hydroquinone; aromatic dicarboxylic acids such as acetic anhydride and terephthalic acid; and polyesters such as polyethylene terephthalate. A method for producing a polymer, oligomer or bis (β-hydroxyethyl) ester of an aromatic dicarboxylic acid such as bis (β-hydroxyethyl) terephthalate by a deacetic acid polycondensation reaction.

(3) A method in which 1,2-bis (4-hydroxybenzoyl) ethane disclosed in JP-A-3-59024 is used as a part of the starting material in the production method of (1) or (2).

The melting point of the liquid crystalline polyester of the present invention (T
m, ° C) must satisfy the following equation (1).

[0018] ^{-10 <Tm-0.0769x 2 + 8.20x} -401.5 <10 ... (1) x here (1) wherein the structural unit of the structural unit (III)
The ratio (mol%) to the total of (I), (II) and (III ) is shown.

Even when the composition ratio of the structural units (I) to (IV) satisfies the above conditions, if the melting point of the above formula (1) is deviated due to the difference in the composition distribution and homogeneity of the polymer. It is not preferable because the fluidity and the mechanical properties of the molded product become poor, and the foaming during melting increases, and the melt spinnability becomes poor.

The liquid crystalline polyester of the present invention preferably has a melting point width of 30 ° C. or less and / or a temperature difference between a flow start temperature and a melting end temperature determined from a temperature dependence curve of a complex viscosity of 25 ° C. or less. . When the melting point width is larger than 30 ° C. or / and the temperature difference between the flow start temperature and the melting end temperature exceeds 25 ° C., the homogeneity of the polymer is not sufficient, which is not preferable.

Here, the melting point (Tm) refers to an endothermic peak temperature (Tm) observed when a polymer that has been polymerized is measured from room temperature under a heating condition of 40 ° C./min.
After observation at m ₁ ), the temperature was maintained at Tm ₁ + 20 ° C. for 5 minutes, then cooled once to room temperature at a temperature lowering condition of 20 ° C./min, and observed again at a temperature rising condition of 20 ° C./min. Endothermic peak temperature (Tm ₂ ). The melting point width refers to the temperature difference between the intersection of the tangent and the baseline from the point where the absolute value of the slope is the largest before and after the endothermic peak (Tm ₂ ).

From the viewpoint of homogeneity of the polymer, it is preferable that Tm ₁ and Tm _{2 have} a relationship of | Tm ₁ −Tm ₂ | ≦ 10 ° C., and | Tm ₁ −Tm ₂ | ≦ 6 ° C. More preferred.

The temperature difference between the flow start temperature and the melting end temperature is determined by the following method. A sample is placed between flat plates (or flat plate-cone) of a rotational viscometer, and heated to a temperature equal to or higher than the melting point, and the sample is placed. The sample is cooled below the crystallization temperature, heated at a rate of 2 ° C./min, and the complex viscosity is measured. In the obtained temperature dependence curve of the complex viscosity, the temperature at which the melt viscosity starts to decrease sharply was defined as the flow start temperature, and the temperature at which the melt viscosity stopped decreasing was defined as the melting end temperature, and the temperature difference between the two was determined. Actually, a tangent was drawn for the complex viscosity in the solid state and the molten state, and a tangent was drawn for the transition state, and each temperature was determined from the intersection of these tangents. Note that complex viscosity can be obtained the complex shear modulus by dividing the complex shear modulus determined from dynamic viscoelasticity measurement giving sinusoidal strain of micro the sample i _omega (although, i ² = -1) .

In order to achieve the object of the present invention, a reaction mainly involving acetylation is carried out in a first vessel (hereinafter referred to as a reaction vessel) in a deacetic acid polycondensation reaction. When the polymerization is carried out in the polymerization vessel in the second vessel (hereinafter referred to as polymerization vessel), the amount of distillate distilled out of the reaction vessel is 80% or more of the theoretical distillate amount, Preferably, the reactants are transferred to a polymerization vessel. When the pressure is reduced at the final polymerization temperature, the pressure is reduced to 100 to 600 Torr, preferably 200 to Torr.
It is preferable to maintain the degree of reduced pressure for 15 minutes or more between 500 Torr. Furthermore, after discharging the molten polymer,
In a batch-type continuous polymerization process of repeating the polymerization was charged next raw material to the same polymerization vessel, when ejecting the polymer, the following internal volume 1 m ³ per 30kg of the polymerization vessel Kanzan polymer weight,
It is preferable to input the next raw material.

Although these polycondensation reactions proceed without a catalyst, it is sometimes preferable to add a metal compound such as stannous acetate, tetrabutyl titanate, potassium acetate and sodium acetate, antimony trioxide, and metallic magnesium. .

Some of the above liquid crystalline polyesters that can be preferably used in the present invention can be measured for logarithmic viscosity in pentafluorophenol.
1.0 to 3.0 as measured at 60 ° C. at a concentration of g / dl.
dl / g is preferred.

The molecular weight distribution of the liquid crystalline polyester of the present invention can be determined, for example, by referring to the Journal of Polymers, Vol. 45, p.
Although it can be measured by the method described in 8), from the viewpoint of homogeneity of the polymer, the value of the ratio MW / MN of the weight average molecular weight (MW) to the number average molecular weight (MN) indicating the molecular weight distribution is 3.0. Is preferably less than 2.9, more preferably less than 2.9.

The liquid crystalline polyester of the present invention preferably has a poise of 10 to 20,000 poise, and more preferably 20 to 1 poise.
0000 poise is more preferred.

The melt viscosity is calculated as melting point (Tm) +10
It is a value measured by a Koka type flow tester under the condition of ° C and a shear rate of 1,000 (1 / second).

Good flame retardancy can be imparted to the liquid crystalline polyester of the present invention by adding an organic flame retardant.

The organic flame retardant that can be used in the present invention is an organic bromine compound and / or an organic phosphorus compound.

The organic bromine compound has a bromine atom in the molecule, and preferably has a bromine content of 20% by weight or more. Specifically, low molecular weight organic bromine compounds such as decabromodiphenyl ether and ethylene bis- (tetrabromophthalimide), brominated polycarbonate (for example, a polycarbonate oligomer produced from brominated bisphenol A or a copolymer thereof with bisphenol A) Products), brominated epoxy compounds (for example, a diepoxy compound produced by reacting brominated bisphenol A with epichlorohydrin or a monoepoxy compound obtained by reacting brominated phenols with epichlorohydrin), poly (brominated benzyl acrylate), Brominated polyphenylene ether, brominated bisphenol A, condensate of cyanuric chloride and brominated phenol, brominated polystyrene, cross-linked brominated polystyrene, cross-linked brominated poly α-methylstyrene Halogenated polymers or oligomers, or mixtures thereof, among which ethylene bis- (tetrabromophthalimide), brominated epoxy oligomers or polymers, brominated polystyrene, cross-linked brominated polystyrene, brominated polyphenylene ether and bromine Brominated polycarbonate is preferred, and ethylene bis- (tetrabromophthalimide), brominated polystyrene, and brominated polycarbonate can be particularly preferably used.

The addition amount of these organic bromine compounds is preferably from 0.2 to 30 parts by weight, more preferably from 0.5 to 20 parts by weight, based on 100 parts by weight of the liquid crystalline polyester. Since there is a close relationship with the copolymerization amount of the structural unit (III), the following addition amount is preferable. That is, the amount of the organic bromine compound is preferably from 60 to 280 parts by weight, particularly preferably from 100 to 200 parts by weight, per 100 parts by weight of the structural unit (III) in the liquid crystalline polyester.

On the other hand, the organic phosphorus compound has a phosphorus atom in the molecule, and is a compound synthesized from phosphoric acid, phosphorous acid, or phosphonic acid, a compound such as phosphine, phosphine oxide, or phosphorane, or a compound represented by the following structural formula. Compounds and polymers containing these compounds as at least one component.

[0035]

Embedded image (Here, R ₃ represents a monovalent aliphatic hydrocarbon group having 1 to 6 carbon atoms and / or a monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms).

Examples of the polymer include a polymer having the following structural unit.

[0037]

Embedded image (Where R ₃ is the same as in the above formula 9; R ₄ is a divalent aliphatic hydrocarbon group having 1 to 6 carbon atoms and / or a divalent aromatic hydrocarbon group having 6 to 20 carbon atoms) And Ar represents a trivalent aromatic hydrocarbon group having 6 to 20 carbon atoms).

Among these, the most preferred organic phosphorus compounds are the following polymers.

[0039]

Embedded image (Here, R ₃ and R ₄ are the same as those in Chemical formulas 9 to 10.) R ₄ may be a metal salt in part of these organic phosphorus compounds.

These organic phosphorus compounds are added in an amount of 0.2 to 30 parts by weight per 100 parts by weight of the liquid crystalline polyester.
Preferably 0.5 to 15 parts by weight, structural unit (III)
Is preferably 2 to 150 parts by weight with respect to 100 parts by weight of
10 to 110 parts by weight are more preferred.

In the present invention, the organic phosphorus compound may be an organic phosphorus compound containing a bromine atom, such as a polymer comprising the following structural units.

[0042]

Embedded image (Here, R ₃ is the same as in the above formula 9.)
By adding a reinforcing agent and a filler to the liquid crystalline polyester of the present invention, mechanical properties and heat resistance can be further improved.

When a reinforcing agent and a filler are added, the amount is preferably 200 parts by weight or less, more preferably 15 to 150 parts by weight, based on 100 parts by weight of the liquid crystalline polyester.

Examples of the reinforcing agent and filler that can be used in the present invention include glass fiber, carbon fiber, aromatic polyamide fiber, potassium titanate fiber, gypsum fiber, brass fiber, stainless steel fiber, steel fiber, ceramic fiber, and boron. Whisker fiber, asbestos fiber, graphite, mica, talc, silica, calcium carbonate, glass beads, glass flake, glass micro balloon,
Fibrous, powdery, granular or plate-like inorganic fillers such as clay, wollastenite, titanium oxide, molybdenum disulfide and the like can be mentioned. Further, as for these reinforcing agents and fillers, those treated with a silane-based, titanate-based coupling agent, or other surface treatment agents may be used.

Further, the liquid crystalline polyester of the present invention includes:
Antioxidants and heat stabilizers (for example, hindered phenols, hydroquinones, phosphites and substituted products thereof) to the extent that the object of the present invention is not impaired,
UV absorbers (eg, resorcinol, salicylate, benzotriazole, benzophenone, etc.), lubricants and release agents (eg, montanic acid and its salts, esters, half esters thereof, stearyl alcohol, stearamide, polyethylene wax, etc.), dyes (eg, nitrosine, etc.) ) And pigments (for example, cadmium sulfide, phthalocyanine, carbon black, etc.), and other additives such as colorants, plasticizers, antistatic agents, and other thermoplastic resins to impart predetermined properties. it can.

The method of adding these is preferably melt kneading, and a known method can be used for melt kneading. For example, Banbury mixer, rubber roll machine,
Using a kneader, single screw or twin screw extruder, etc.
The composition can be melt-kneaded at a temperature of from about 350 ° C. to a composition.

The thus obtained liquid crystalline polyester of the present invention having improved homogeneity can be obtained only by a melt polymerization method and has excellent melt fluidity, melt spinnability and optical anisotropy. It can be processed into three-dimensional molded products, containers, hoses, fibers, films, and the like having excellent mechanical properties by blow molding, spinning, and the like.

[0048]

The present invention will be described in more detail with reference to the following examples.

[0049] Example 1 vertical and horizontal reactor which ratio the scraping-down direction of the helical ribbon blade into the polymerization apparatus having an inner volume of 0.1 m ³ of 2.5 is provided with a stirrer fitted to a height of 0.035 m ³ And a polymerization vessel for polycondensation were used to polymerize as follows.

The reaction vessel was charged with 18.6 p-hydroxybenzoic acid.
kg, 4,4′-dihydroxybiphenyl 2.7 kg,
9.6 kg of polyethylene terephthalate, 2.5 kg of terephthalic acid and 18.5 kg of acetic anhydride were charged, and the temperature in the reaction vessel was adjusted to 130 to 250 ° C. over 5 hours, and 25
Stirring was continued at 0 ° C. for 30 minutes. The distillate volume at this point is 1
7.6 kg, which was 82% of the theoretical distillation amount. Thereafter, the reaction product was transferred to a polymerization vessel, and the temperature in the vessel was raised to 250 to 280 ° C. over 2 hours.
The pressure was reduced to orr, and stirring was continued for 1 hour while maintaining the degree of vacuum at 250 Torr. 1 Torr over 50 minutes
Then, stirring was continued for 2 hours to complete polycondensation. Then, after pressurizing the inside of the polymerization can to 4 kg / cm ² , the polymer was discharged in a strand shape via a die.

The theoretical structural formula of the obtained liquid crystalline polyester is as follows.

[0052]

Embedded image k / l / m / n = 67.5 / 7.5 / 25 / 32.5 This liquid crystalline polyester was obtained from PerkinElmer DS
When the melting point and the melting point width were measured using the Model C-7 under the above conditions, the peak temperature of Tm ₁ was 246 ° C., the peak temperature of Tm ₂ was 244 ° C., and the melting point width was 20 ° C. T
the m ₂ was calculated with the following equation (2) as Tm -0.6
° C.

Tm−0.0769 × ² + 8.20 × −401.5 (2) The temperature difference between the flow start temperature and the melting end temperature was measured using an MR-3 liquid meter manufactured by Rheology. 15 ° C.

The logarithmic viscosity of this polymer is 1.52 d
1 / g (measured in pentafluorophenol at a concentration of 0.1 g / dl at 60 ° C.).

The liquid crystalline polyester obtained in order to check the melt spinning property was vacuum-dried, melt-spun at 260 ° C. using a single-hole die having a hole diameter of 0.1 mmφ, and wound at a speed of 600 m / min. A good monofilament could be obtained without breakage.

Further, 45 parts by weight of a glass fiber having a fiber diameter of about 9 μm and a fiber length of 3 mm was dry-blended with respect to 100 parts by weight of this polymer, and then melt-kneaded and pelletized at 260 ° C. by a 30 mmφ twin screw extruder.

The obtained pellets were supplied to a Sumitomo Nestal injection molding machine Promat (manufactured by Sumitomo Heavy Industries, Ltd.), and a bending test piece (1/8 "×) was prepared at a cylinder temperature of 260 ° C. and a mold temperature of 90 ° C. 1/2 "x 5").
Injection speed 99
%, 0.5 mm under the condition of injection pressure 500 kgf / cm ²
The flow length (rod flow length) of a test piece having a thickness of 12.7 mm width was obtained.

As a result, the bending strength was 1750 kgf / c.
m ² , the rod flow length was 125 mm, indicating good flowability and mechanical properties.

Comparative Example 1 Using the same apparatus as in Example 1, deacetic acid polymerization was carried out under the following conditions.

The reaction vessel was charged with 12.4 p-hydroxybenzoic acid.
kg, 4,4'-dihydroxybiphenyl 11.2k
g, 9.6 kg of polyethylene terephthalate, 8.3 kg of terephthalic acid and 23.6 kg of acetic anhydride,
The temperature in the reaction can is increased to 130 to 230 ° C over 5 hours,
Stirring was continued at 230 ° C. for 30 minutes. The distillate amount at this point was 18.8 kg, which was 74% of the theoretical distillate amount.
Thereafter, the reaction product was transferred to a polymerization vessel, the temperature in the vessel was raised to 230 to 280 ° C over 2 hours, the pressure in the polymerization vessel was reduced to 1.0 Torr, and stirring was continued at 280 ° C for 2 hours to complete the polycondensation. Then, after pressurizing the inside of the polymerization can to 4 kg / cm ² , the polymer was discharged in a strand shape via a die.

The theoretical structural formula of the obtained liquid crystalline polyester is as follows.

[0062]

Embedded image k / l / m / n = 45/30/25/55 When the melting point and the melting point width of this liquid crystalline polyester were measured in the same manner as in Example 1, the peak temperature of Tm ₁ was 269.
℃, Tm ₂ peak temperature is 258 ℃, melting point width is 35 ℃
Met. It was 13 ° C. when calculated using the formula (2) of Example 1 with Tm ₂ as Tm. The temperature difference between the flow start temperature and the melting end temperature was 30 ° C.

The logarithmic viscosity of this polymer is 1.64 d.
1 / g (measured in pentafluorophenol at a concentration of 0.1 g / dl at 60 ° C.).

When the fiber was spun at a spinning temperature of 275 ° C. in the same manner as in Example 1, no good monofilament could be obtained due to severe yarn breakage.

This polymer was mixed with glass fiber and pelletized in the same manner as in Example 1 except that the extrusion temperature was changed to 275 ° C.
The bending strength and rod flow length were determined in the same manner as in Example 1 except that the cylinder temperature was 275 ° C. As a result, the bending strength was 1590.
kgf / cm ² , the rod flow length was 82 mm, and the fluidity and mechanical properties were greatly reduced.

[0066]

According to the present invention, a molded article which is obtained only by melt polymerization, has excellent melt fluidity and optical anisotropy, and has excellent mechanical properties by a usual molding method is provided. Instead, it is possible to obtain a liquid crystalline polyester having improved homogeneity and excellent melt spinnability.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int. Cl. ⁷ , DB name) C08G 63/00-63/91

Claims (2)

(57) [Claims] 1. The following structural units (I), (II), (III) and (IV)
And the sum of structural units (I) and (II) is the structural unit
60 to 80 mol based on the total of (I), (II) and (III)
%, Structural unit (III) is structural units (I), (II) and (III)
20 to 40 mol% of the total of the structural units (I)
The molar ratio [(I) / (II)] to the unit (II) is from 78/22 to
93/7 liquid crystalline polyester having a melting point (T
m, ° C.) satisfy the formula (1), and the logarithmic viscosity at which the melting point width determined by differential calorimetry is 30 ° C. or less is 1.0 to 3.
A liquid crystalline polyester having improved homogeneity, characterized in that the polyester is 0 dl / g. Embedded image (Where R ₁ is R ₂ represents one or more groups selected from Represents one or more groups selected from In the formula, X represents a hydrogen atom or a chlorine atom, and the total of the structural units (II) and (III) and the structural unit (IV) are substantially equimolar). −10 <Tm−0.0769 × ² + 8.20 × −401.5 <10 (1) (where x in the formula (1) is a structural unit of the structural unit (III))
Ratio (mol%) to the sum of (I), (II) and (III)
Is shown). 2. The liquid crystalline polyester according to claim 1, wherein a temperature difference between a flow start temperature and a melting end temperature determined from a temperature dependency curve of a complex viscosity is 25 ° C. or less.