Liquid crystal polyester resin, molded article and electrical / electronic component

Abstract

[Problem] To provide a liquid crystal polyester resin having desired polymer physical properties. [Solution] This liquid crystal polyester resin contains constituent units derived from three or more types of hydroxycarboxylic acid, and said resin is characterized by the condition: the proportion of ester bonds formed between a hydroxycarboxylic acid that constitutes the most abundant constituent unit among the constituent units derived from the three or more types of hydroxycarboxylic acid and the same type of hydroxycarboxylic acid is 12-60% relative to the total amount of ester bonds present in the liquid crystal polyester resin.

Description

Liquid crystal polyester resin, molded products, and electrical and electronic parts

[0001] The present invention relates to a liquid crystal polyester resin, a molded article containing the liquid crystal polyester resin, and an electric / electronic part including the molded article.

[0002] Liquid crystal polymers (LCPs), such as liquid crystal polyesters and polyamides, possess high heat resistance due to their rigid backbones, which are formed by connecting aromatic monomers with strong ester or amide bonds. Liquid crystal polymers exhibit low viscosity and excellent melt-processability due to the molecularly oriented liquid crystal phase they exhibit when melted. While p-hydroxybenzoic acid (HBA), the most basic repeating unit in the synthesis of liquid crystal polyesters, can be homopolymerized, the melting point of HBA homopolymers is believed to exceed the decomposition temperature of liquid crystal polymers, making them unmelt-processable. Therefore, copolymerizing HBA with a monomer other than HBA to form a random copolymer reduces the excessively high crystallinity, lowering the melting point of the liquid crystal polymer and making it melt-processable. Furthermore, by finding a balance that maintains high heat resistance, highly heat-resistant and easily moldable polymers have been developed. LCPs with particularly excellent heat resistance are known, including those in which a single hydroxycarboxylic acid is copolymerized with a diol or dicarboxylic acid.

[0003] Many methods are known for controlling the physical properties of LCPs by changing the types and compositional ratios of the monomers that make up the LCP. In recent years, in response to the trend toward miniaturization of electronic components, LCP designs have been reported that increase the number of constituent monomers to impart high fluidity and fillability during melt molding. Patent Document 1 reports increasing the number of hydroxycarboxylic acids to two, thereby increasing the number of monomer types to five, thereby achieving high fluidity and low warpage. Patent Document 2 also reports an LCP that exhibits excellent fluidity and mechanical strength by using five monomers, including two hydroxycarboxylic acids. However, while both Patent Documents 1 and 2 improve moldability, the melting point, which is the most basic heat resistance indicator of the resulting LCP, tends to decrease as the number of monomers used increases and the compositional ratio of the constituent units approaches uniformity, which poses a problem.

[0004] Increasing the number of monomer species constituting an LCP means equalizing the compositional ratios of the constituent monomers in the LCP among the monomers and increasing the randomness of the LCP, which is a random copolymer, so the problem of the melting point decrease is essentially unavoidable when increasing the number of monomer species. This can also be seen from Non-Patent Document 1, which shows that when the compositional ratio of an LCP made of two hydroxycarboxylic acids, HBA and 2-hydroxy-6-naphthoic acid (HNA), is changed, the change in melting point decreases as the compositional ratios are equalized.

[0005] JP 2017-137438 JP 2012-126842 WO 2011 / 18837

[0006] Journal of Applied Polymer Science, Vol. 62, 1049-1056 (1996)

[0007] On the other hand, the physical properties of LCPs can be controlled from perspectives other than the type of structural units and their composition ratios. For example, there are methods for controlling the sequence and chain length of specific monomers in LCPs. As an example, in LCPs that are copolymers of multiple types of monomers and form random polymers, the same specific monomers undergo localized continuous polymerization, forming single continuous sequences, which can affect the physical properties and quality of the polymer. The generation of continuous sequences of specific monomers is particularly problematic in LCPs that use aromatic hydroxycarboxylic acid monomers that can be polymerized independently. When a specific aromatic hydroxycarboxylic acid undergoes homopolymerization beyond a certain chain length, it can create localized high-melting-point regions with significantly elevated melting points compared to the surrounding regions. The presence of high-melting-point regions can result in regions that do not melt at the heating temperature set for the surrounding regions during molding, leading to processing problems such as plugging of flow channels and molding machine nozzles, particularly in micromolding. In addition to localized generation, the average chain length of specific monomers in the system can also affect various physical properties of LCPs. Patent Document 3 shows that by setting the average chain length of HNA in a copolymerized LCP containing HNA as the main aromatic hydroxycarboxylic acid and further incorporating an aromatic diol and an aromatic dicarboxylic acid within a certain short and preferable range, the fluidity and mechanical properties of the resulting polymer during processing can be favorably controlled. This document shows that even for LCPs with the same structural units and composition, controlling the average chain length of HNA can improve the physical properties of the LCP, including fluidity. However, the design in Patent Document 3 did not achieve melting point control by controlling the average chain length at the same composition.

[0008] Patent Document 3 discloses that an actual method for controlling the continuous chain length of HNA (more preferable conditions) is to heat the end temperature of the melt polymerization to a high temperature between 25°C and 35°C above the melting point of the resulting LCP. This is thought to be a method for controlling the continuous chain length of aromatic hydroxycarboxylic acid in the system by raising the end temperature of the reaction and inducing transesterification involving the less reactive aromatic diol or aromatic dicarboxylic acid at the end of the reaction, since aromatic hydroxycarboxylic acid monomers have a faster reaction rate during melt polymerization than aromatic diols or aromatic dicarboxylic acids. However, the method for controlling the average chain length when multiple hydroxycarboxylic acids with similar reactivities are used, and the control of various physical properties by the average chain length, have not been elucidated.

[0009] The present inventors increased the number of hydroxycarboxylic acid species from two to two in order to improve moldability and fillability during melting. This was done to reduce the probability of specific hydroxycarboxylic acids bonding together. Previous studies have not clarified the chain length of hydroxycarboxylic acids synthesized using multiple hydroxycarboxylic acid species, nor the changes in the main chain sequence state related to polymerization conditions as shown in Patent Document 1, nor the associated control of polymer properties. Furthermore, in liquid crystal polyester resins using three or more hydroxycarboxylic acids, optimization of polymer properties by controlling the main chain sequence state has not been achieved, and there have been challenges in optimizing such properties from the perspective of material performance.

[0010] Therefore, the present inventors evaluated the main chain sequence state (repeating pattern of monomeric structural units) of liquid crystal polyester resins using three or more hydroxycarboxylic acids and compared the physical properties of the polymer. As a result, the present inventors discovered a liquid crystal polyester resin that has improved thermal properties compared to LCPs with the same monomer composition ratio by controlling the proportion of ester bonds formed between the most abundant hydroxycarboxylic acid among the structural units derived from three or more hydroxycarboxylic acids and the hydroxycarboxylic acid of the same type. The present invention was completed based on this finding.

[0011] Therefore, an object of the present invention is to provide a liquid crystalline polyester resin having desired polymer properties. Another object of the present invention is to provide a molded article containing the liquid crystalline polyester resin and an electric / electronic component including the molded article.

[0012] That is, the present invention provides the following inventions. [1] A liquid-crystalline polyester resin containing structural units derived from three or more hydroxycarboxylic acids, characterized in that the liquid-crystalline polyester resin satisfies the following condition: the proportion of ester bonds formed between the hydroxycarboxylic acid of the most abundant structural unit among the structural units derived from the three or more hydroxycarboxylic acids and the hydroxycarboxylic acid of the same type is 12% or more and 60% or less of all ester bonds present in the liquid-crystalline polyester resin. [2] The liquid-crystalline polyester according to [1], in which the compositional ratio of the structural units derived from the three or more hydroxycarboxylic acids is 50 mol% or more of all structural units of the liquid-crystalline polyester resin. [3] The liquid-crystalline polyester resin according to [1] or [2], in which the compositional ratio of the structural unit derived from the three or more hydroxycarboxylic acids of the most abundant structural unit among the structural units derived from the three or more hydroxycarboxylic acids is 40 mol% or more and 98 mol% or less of all structural units derived from the three or more hydroxycarboxylic acids. [4] The liquid crystal polyester resin according to any one of [1] to [3], wherein the composition ratio of the second most abundant structural unit among the structural units derived from the three or more hydroxycarboxylic acids is 1 mol % or more and 40 mol % or less relative to all structural units derived from the three or more hydroxycarboxylic acids. [5] The liquid crystal polyester resin according to any one of [1] to [4], wherein the composition ratio of the third most abundant structural unit among the structural units derived from the three or more hydroxycarboxylic acids is 0.1 mol % or more and 20 mol % or less relative to all structural units derived from the three or more hydroxycarboxylic acids. [6] The liquid crystal polyester resin according to [3], wherein the first most abundant structural unit among the structural units derived from the three or more hydroxycarboxylic acids is a structural unit derived from p-hydroxybenzoic acid or a structural unit derived from 6-hydroxy-2-naphthoic acid. [7] The liquid crystal polyester resin according to [4], wherein the second most abundant structural unit among the structural units derived from the three or more hydroxycarboxylic acids is a structural unit derived from p-hydroxybenzoic acid or a structural unit derived from 6-hydroxy-2-naphthoic acid.[8] The liquid crystal polyester resin according to any one of [1] to [7], wherein the melting point of the liquid crystal polyester resin is 270°C or higher and 370°C or lower. [9] The liquid crystal polyester resin according to any one of [1] to [8], wherein the melt viscosity measured at a temperature of the melting point of the liquid crystal polyester resin to a temperature of the melting point plus 30°C or higher at a shear rate of 1000 / s is 1 Pa·s or higher.

[10] The liquid crystal polyester resin according to any one of [1] to [9], wherein the deflection temperature under load of the liquid crystal polyester resin is 180°C or higher.

[11] A fibrous molded article comprising the liquid crystal polyester resin according to any one of [1] to

[10] .

[12] A sheet-shaped molded article comprising the liquid crystal polyester resin according to any one of [1] to

[10] .

[13] An injection-molded article comprising the liquid crystal polyester resin according to any one of [1] to

[10] .

[14] An electric / electronic component comprising the molded article according to

[11] .

[15] An electric / electronic component comprising the molded article according to

[12] .

[16] An electric / electronic component comprising the molded product according to

[13] .

[0013] According to the present invention, a liquid crystal polyester resin having desired polymer properties can be provided. Furthermore, according to the present invention, a molded article containing the liquid crystal polyester resin and an electric / electronic component including the molded article can be provided.

[0014] In particular, in the present invention, by controlling the sequence state of the main chain within a specific range in a liquid crystal polyester resin using three or more types of hydroxycarboxylic acids, the thermal properties of a liquid crystal polyester resin having the same type of structural units and the same degree of polymerization can be further improved.

[0015] Reference Example 1 １３ 1 is a CNMR spectrum of Reference Example 2. １３ 1 is a CNMR spectrum of Example 1-1. １３ 1 is a CNMR spectrum of Example 1-2. １３ 1 is a CNMR spectrum of Examples 1-3. １３ 1 is a CNMR spectrum of Comparative Example 1-1. １３ 1 is a CNMR spectrum. Modes for carrying out the invention

[0016] (Liquid Crystal Polyester Resin) The liquid crystal polyester resin according to the present invention contains structural units (I) derived from three or more hydroxycarboxylic acids, and may further contain structural units (II) derived from dicarboxylic acids and structural units (III) derived from diols. The liquid crystal polyester resin according to the present invention may be a single substance or a mixture (polymer blend).

[0017] In the liquid crystal polyester resin according to the present invention, the composition ratio of the structural unit (I) derived from three or more hydroxycarboxylic acids is preferably 50 mol% or more, more preferably 60 mol% or more, even more preferably 70 mol% or more, still more preferably 90 mol% or more, and most preferably 95 mol% or more, based on the total structural units of the liquid crystal polyester resin. By appropriately setting the hydroxycarboxylic acid ratio to exceed half of the structural units in the liquid crystal polyester resin, the contribution to the liquid crystal polyester resin that exhibits the effects of the present invention can be increased, and the physical property control effect can be improved.

[0018] The liquid crystal polyester resin according to the present invention is characterized by satisfying the following condition: the proportion of ester bonds formed between the hydroxycarboxylic acid that is the most abundant structural unit among the structural units derived from three or more hydroxycarboxylic acids and the hydroxycarboxylic acid of the same type is 12% or more and 60% or less of all ester bonds present in the liquid crystal polyester resin. The lower limit of this proportion is preferably 20% or more, more preferably 30% or more, even more preferably 35% or more, and even more preferably 40% or more, and the upper limit is preferably 57% or less, more preferably 55% or less, even more preferably 53% or less, and even more preferably 50% or less. In the present invention, the "proportion of ester bonds formed between hydroxycarboxylic acids of the same type" refers to the proportion of ester bonds (self-linkages) formed between structural units derived from three or more hydroxycarboxylic acids present in the liquid crystal polyester resin and the same hydroxycarboxylic acid relative to all ester bonds present in the liquid crystal polyester resin. If this proportion is within the above numerical range, the thermal properties of liquid crystal polyester resins having the same structural units and the same degree of polymerization can be further improved. In order to control the sequence state of the main chain, the liquid crystal polyester resin is preferably obtained through solid phase polymerization.

[0019] The "proportion of ester bonds formed between a hydroxycarboxylic acid and the same kind of hydroxycarboxylic acid" can be calculated by measuring the total amount of ester bonds present in the liquid crystal polyester resin and the amount of ester bonds formed between the hydroxycarboxylic acid and the same kind of hydroxycarboxylic acid by NMR. For example, １３In the NMR spectrum obtained by C-NMR, the chemical shift value (ppm) of the carbonyl carbon of the ester bond in the liquid crystal polyester resin is identified. Usually, the carbonyl carbon (COO) of the ester bond tends to be detected at 165-175 ppm. The peak between the chemical shift values ​​is confirmed, and the type of ester bond corresponding to that peak is identified. Therefore, in the present invention, the "proportion of ester bonds formed between the most abundant hydroxycarboxylic acid among the structural units derived from three or more hydroxycarboxylic acids and the same hydroxycarboxylic acid" can be obtained by dividing the integral ratio of the peak of the carbonyl carbon of the ester bond between the most abundant hydroxycarboxylic acid and the same hydroxycarboxylic acid by the sum of the integral ratios of the peaks of all ester bonds present in the liquid crystal polyester resin, which are detected mainly at 165-175 ppm. Specific identification methods will be described in detail in the Examples. １３ The solvent used for C-NMR measurement is not particularly limited as long as it dissolves the liquid crystal polyester resin, and examples thereof include pentafluorophenol, a mixed solvent of pentafluorophenol and chloroform, etc. The concentration of the liquid crystal polyester resin when dissolved in the solvent is also not particularly limited as long as it dissolves the liquid crystal polyester resin, and is preferably within the range of, for example, 1 to 10 mass %. １３ There is no particular restriction on the number of times that the C-NMR measurement is accumulated, as long as a sufficient S / N ratio of the desired carbonyl carbon can be obtained, but it is preferably about 10,000 to 40,000 times, for example. １３ The C-NMR measurement is preferably carried out at a temperature of, for example, 20 to 120°C.

[0020] The lower limit of the melt viscosity of the liquid crystal polyester resin according to the present invention, measured at a melting point to melting point + 30°C and a shear rate of 1000 / s, is 1 Pa·s or more, preferably 5 Pa·s or more, more preferably 10 Pa·s or more, even more preferably 20 Pa·s or more, and even more preferably 30 Pa·s or more. The upper limit of the melt viscosity is preferably 300 Pa·s or less, more preferably 200 Pa·s or less, even more preferably 100 Pa·s or less, and even more preferably 80 Pa·s or less. By setting the melt viscosity of the liquid crystal polyester resin according to the present invention within the above numerical range, a liquid crystal polyester resin having excellent melt processability under high temperature conditions can be obtained. In this specification, the viscosity of the liquid crystal polyester resin can be measured using a capillary rheometer viscometer in accordance with JIS K7199.

[0021] In consideration of heat resistance, the lower limit of the melting point of the liquid crystal polyester resin according to the present invention is preferably 270 ° C. or higher, more preferably 280 ° C. or higher, even more preferably 290 ° C. or higher, still more preferably 300 ° C. or higher, and most preferably 305 ° C. or higher, and the upper limit is not particularly limited, but is preferably 370 ° C. or lower, more preferably 360 ° C. or lower, even more preferably 340 ° C. or lower, and still more preferably 330 ° C. or lower. The lower limit of the crystallization point of the liquid crystal polyester resin according to the present invention is preferably 230 ° C. or higher, more preferably 235 ° C. or higher, even more preferably 240 ° C. or higher, and still more preferably 245 ° C. or higher, and the upper limit is preferably 290 ° C. or lower, more preferably 280 ° C. or lower, even more preferably 275 ° C. or lower, and still more preferably 270 ° C. or lower. By setting the melting point and crystallization point of the liquid crystal polyester resin according to the present invention within the above-mentioned ranges, it is easy to adjust the melt viscosity (1000 / s) at the melting point + (10 to 30) ° C. within the above-mentioned desired range, and it is also possible to improve the heat resistance of molded articles produced using the liquid crystal polyester resin during heat processing or in high-temperature, high-load environments. In this specification, the melting point of the liquid crystal polyester resin is a value measured using a differential scanning calorimeter (DSC). Specifically, the liquid crystal polyester resin was heated from room temperature to 360 ° C. at a heating rate of 10 ° C. / min to completely melt, and then cooled to 30 ° C. at a rate of 10 ° C. / min. The apex of the exothermic peak obtained when the temperature was increased from room temperature to 360 ° C. was defined as the crystallization point (Tc), and the apex of the endothermic peak obtained when the temperature was further increased to 360 ° C. at a rate of 10 ° C. / min was defined as the melting point (Tm).

[0022] The lower limit of the deflection temperature under load (DTUL) of the liquid crystal polyester resin according to the present invention is preferably 180°C or higher, taking into consideration practical heat resistance. By setting the deflection temperature under load (DTUL) of the liquid crystal polyester resin according to the present invention within the above numerical range, the practical heat resistance of molded articles produced using the liquid crystal polyester resin against heat processing can be improved. In this specification, the deflection temperature under load (DTUL) of the liquid crystal polyester resin is a value measured at a load of 1.8 MPa in accordance with ASTM D648 using a bending test piece (80mm x 12mm x 2mm) produced by injection molding.

[0023] The liquid crystallinity of the liquid crystal polyester resin according to the present invention can be confirmed by using a polarizing microscope (product name: DS-Ri2) manufactured by Nikon Corporation equipped with a hot stage for microscope (product name: 10083L) manufactured by Japan High Tech Co., Ltd., and then heating and melting the liquid crystal polyester resin on a heated stage of the microscope, and then observing whether or not it has optical anisotropy.

[0024] Hereinafter, each of the structural units contained in the liquid crystal polyester resin according to the present invention will be described in detail.

[0025] (Structural unit (I) derived from hydroxycarboxylic acid) The structural unit (I) derived from hydroxycarboxylic acid contains structural units derived from three or more hydroxycarboxylic acids. The composition ratio of the structural unit with the largest number among the structural units derived from three or more hydroxycarboxylic acids, relative to all structural units derived from three or more hydroxycarboxylic acids, is preferably 40 mol% or more, more preferably 50 mol% or more, even more preferably 60 mol% or more, still more preferably 65 mol% or more, and the upper limit is 98 mol% or less, more preferably 95 mol% or less, even more preferably 90 mol% or less, still more preferably 85 mol% or less. By setting the composition ratio of the structural unit with the largest number within this range, the heat resistance of the resulting liquid crystal polyester can be designed to be preferably high. Furthermore, the composition ratio of the second most abundant structural unit among the structural units derived from three or more hydroxycarboxylic acids, relative to all structural units derived from three or more hydroxycarboxylic acids, has a lower limit of preferably 1 mol% or more, more preferably 3 mol% or more, even more preferably 8 mol% or more, still more preferably 13 mol% or more, and an upper limit of preferably 40 mol% or less, more preferably 34 mol% or less, even more preferably 32 mol% or less, and still more preferably 28 mol% or less. Furthermore, the composition ratio of the third most abundant structural unit among the structural units derived from three or more hydroxycarboxylic acids, relative to all structural units derived from three or more hydroxycarboxylic acids, has a lower limit of preferably 0.1 mol% or more, more preferably 0.5 mol% or more, even more preferably 1.0 mol% or more, and still more preferably 1.5 mol% or more, and an upper limit of preferably 10 mol% or less, more preferably 7.0 mol% or less, even more preferably 5.0 mol% or less, and still more preferably 3.0 mol% or less.

[0026] Among the structural units derived from three or more hydroxycarboxylic acids, the most abundant structural unit is preferably a structural unit derived from an aromatic hydroxycarboxylic acid, the second most abundant structural unit is preferably a structural unit derived from an aromatic hydroxycarboxylic acid, and the third most abundant structural unit is preferably a structural unit derived from an aromatic hydroxycarboxylic acid. In particular, it is preferable that all of the structural units derived from three or more hydroxycarboxylic acids are structural units derived from aromatic hydroxycarboxylic acids. Furthermore, the structural unit (I) derived from a hydroxycarboxylic acid preferably contains at least a structural unit (A) derived from p-hydroxybenzoic acid and a structural unit (B) derived from 6-hydroxy-2-naphthoic acid, and more preferably further contains a structural unit (C) derived from a hydroxycarboxylic acid other than the structural units (A) and (B). Among the structural units derived from three or more hydroxycarboxylic acids, the most abundant structural unit is preferably a structural unit (A) derived from p-hydroxybenzoic acid or a structural unit (B) derived from 6-hydroxy-2-naphthoic acid. Of the structural units derived from three or more hydroxycarboxylic acids, the second most abundant structural unit is preferably the structural unit (A) derived from p-hydroxybenzoic acid or the structural unit (B) derived from 6-hydroxy-2-naphthoic acid. Of the structural units derived from three or more hydroxycarboxylic acids, the third most abundant structural unit is preferably the structural unit (C) derived from a hydroxycarboxylic acid other than the structural units (A) and (B).

[0027] (Structural Unit (A) Derived from Hydroxycarboxylic Acid) The structural unit (A) derived from hydroxycarboxylic acid is a structural unit derived from p-hydroxybenzoic acid (HBA). Monomers that provide the structural unit (A) include p-hydroxybenzoic acid, its acetylated products, ester derivatives, and acid halides.

[0028] (Structural Unit (B) Derived from Hydroxycarboxylic Acid) The structural unit (B) derived from hydroxycarboxylic acid is a structural unit derived from 6-hydroxy-2-naphthoic acid (HNA). Monomers that provide the structural unit (B) include 6-hydroxy-2-naphthoic acid, its acetylated products, ester derivatives, and acid halides.

[0029] (Structural Unit (C) Derived from Hydroxycarboxylic Acid) The structural unit (C) derived from a hydroxycarboxylic acid is a structural unit derived from a hydroxycarboxylic acid other than the structural units (A) and (B). The structural unit (C) is preferably a structural unit derived from at least one selected from the group consisting of m-hydroxybenzoic acid (mHBA), 6-hydroxynicotinic acid (HNIA), and 4'-hydroxy-4-biphenylcarboxylic acid (HPBA). Of these, a structural unit derived from m-hydroxybenzoic acid is more preferred. Monomers that provide the structural unit (C) include these monomers, as well as acetylated products, ester derivatives, and acid halides thereof.

[0030] The composition ratios (mol %) of the structural units (A) to (C) in the liquid crystal polyester resin, relative to the total amount of structural units (I) derived from hydroxycarboxylic acid, preferably satisfy the following conditions: 1 mol %≦structural unit (A)≦40 mol % 40 mol %≦structural unit (B)≦98 mol % 0.1 mol %≦structural unit (C)≦10 mol %, more preferably satisfy the following conditions: 3 mol %≦structural unit (A)≦34 mol % 50 mol %≦structural unit (B)≦95 mol % 0.5 mol %≦structural unit (C)≦7.0 mol %, and even more preferably satisfy the following conditions: 8 mol %≦structural unit (A)≦32 mol % 60 mol %≦structural unit (B)≦90 mol % 1.0 mol %≦structural unit (C)≦5.0 mol %, and further preferably satisfy the following conditions: 13 mol %≦structural unit (A)≦28 mol % 65 mol %≦structural unit (B)≦85 mol % It is even more preferable that the following relationship be satisfied: 1.5 mol %≦structural unit (C)≦3.0 mol %.

[0031] (Structural Unit (II) Derived from Dicarboxylic Acid) The structural unit (II) derived from a dicarboxylic acid is preferably a structural unit derived from a dicarboxylic acid represented by the following formula (1), and more preferably a structural unit derived from an aromatic dicarboxylic acid. Note that only one type of structural unit (II) may be included, or two or more types may be included.

[0032] In the above formula, Ar ３ is a divalent hydrocarbon group which may have a substituent as desired, and is preferably a divalent hydrocarbon group having an aromatic ring. Examples of hydrocarbon groups having an aromatic ring include a phenyl group, a biphenyl group, a 4,4'-isopropylidenediphenyl group, a naphthyl group, an anthryl group, and a phenanthryl group. Examples of substituents include hydrogen, an alkyl group, an alkoxy group, and fluorine. The alkyl group preferably has 1 to 10 carbon atoms, and more preferably has 1 to 5 carbon atoms. The alkyl group may be a linear or branched alkyl group. The alkoxy group preferably has 1 to 10 carbon atoms, and more preferably has 1 to 5 carbon atoms.

[0033] Examples of monomers that provide the structural unit (II) include terephthalic acid (TPA), isophthalic acid (IPA), 2,6-naphthalenedicarboxylic acid (NADA), and their acylates, ester derivatives, acid halides, etc. The structural unit (II) is preferably a structural unit derived from terephthalic acid.

[0034] The composition ratio (mol %) of the structural unit (II) in the liquid crystal polyester resin relative to the structural unit (I) is preferably more than 0 mol %, more preferably 0.1 mol % or more, even more preferably 0.3 mol % or more, and still more preferably 0.5 mol % or more, and the upper limit is preferably 2.0 mol % or less, more preferably 1.5 mol % or less, even more preferably 1.2 mol % or less, and still more preferably 1.0 mol % or less.

[0035] (Diol-Derived Structural Unit (III)) The diol-derived structural unit (III) is preferably a structural unit derived from a diol represented by the following formula (2), and more preferably a structural unit derived from an aromatic diol. Note that only one type of structural unit (III) may be included, or two or more types may be included.

[0036] In the above formula, Ar １ is a divalent hydrocarbon group which may have a substituent as desired, and is preferably a divalent hydrocarbon group having an aromatic ring. Examples of hydrocarbon groups having an aromatic ring include a phenyl group, a biphenyl group, a 4,4'-isopropylidenediphenyl group, a naphthyl group, an anthryl group, and a phenanthryl group. Examples of substituents include hydrogen, an alkyl group, an alkoxy group, and fluorine. The alkyl group preferably has 1 to 10 carbon atoms, and more preferably has 1 to 5 carbon atoms. The alkyl group may be a linear or branched alkyl group. The alkoxy group preferably has 1 to 10 carbon atoms, and more preferably has 1 to 5 carbon atoms.

[0037] Examples of monomers that provide the structural unit (III) include 4,4'-dihydroxybiphenyl (BP), hydroquinone (HQ), methylhydroquinone (MeHQ), 4,4'-isopropylidenediphenol (BisPA), and acylated products, ester derivatives, and acid halides thereof.

[0038] The composition ratio (mol %) of the structural unit (III) in the liquid crystal polyester resin relative to the structural unit (I) is preferably more than 0 mol %, more preferably 0.1 mol % or more, even more preferably 0.3 mol % or more, and still more preferably 0.5 mol % or more, and the upper limit is preferably 2.0 mol % or less, more preferably 1.5 mol % or less, even more preferably 1.2 mol % or less, and still more preferably 1.0 mol % or less.

[0039] (Method for producing liquid crystal polyester resin) The method for producing a liquid crystal polyester resin according to the present invention includes a step of melt-polymerizing three or more hydroxycarboxylic acids and, if necessary, a dicarboxylic acid and / or a diol to obtain a polymer. The method for producing a liquid crystal polyester resin according to the present invention may further include a step of solid-state polymerizing the polymer (two-stage polymerization).

[0040] From the viewpoint of efficiently obtaining a liquid crystal polyester resin, the melt polymerization is preferably carried out under reflux with acetic acid in the presence of 1.03 to 1.15 molar equivalents of acetic anhydride relative to the total hydroxyl groups of all monomers, and more preferably carried out under reflux with acetic acid in the presence of 1.03 to 1.10 molar equivalents of acetic anhydride.

[0041] The reaction termination temperature (final temperature) of the melt polymerization is determined by polymerizing the liquid crystal polyester resin separately and independently (which may include solid-state polymerization, or may be melt polymerization only, but the reaction termination temperature of the melt polymerization is 313 ° C.), and the melt viscosity (temperature range in which the liquid crystal phase is expressed and 1000 / s) is greater than 20 Pa · s, based on the melting point indicated by the temperature range (melting point -25) to (melting point + 25) ° C., and more preferably within the temperature range (melting point -20) ° C. to (melting point + 20) ° C. Since almost no change in the homopolymerization state occurs in solid-state polymerization compared to melt polymerization, by adjusting the reaction termination temperature of the melt polymerization within the above numerical range, it is possible to control the state of the main chain sequence and obtain a liquid crystal polyester resin with improved thermal properties.

[0042] The melt polymerization is preferably carried out in the presence of a catalyst and without a solvent. As the catalyst, any conventionally known catalyst for polymer polymerization can be used. Examples of the catalyst include metal salt catalysts such as potassium acetate, magnesium acetate, stannous acetate, lead acetate, sodium acetate, tetrabutyl titanate, and antimony trioxide; nitrogen-containing heterocyclic compounds such as N-methylimidazole; and organic compound catalysts. The amount of catalyst used is not particularly limited, but is preferably the total number of moles of monomers × (10 to 100) mg / mol.

[0043] When performing solid-state polymerization, the polymer obtained by melt polymerization may be cooled and solidified, and then pulverized into a powder or flake form. Alternatively, the polymer strands obtained by melt polymerization may be pelletized into pellets. The reaction temperature of the solid-state polymerization is preferably equal to or lower than the melting point, and is preferably from (melting point - 100) ° C to (melting point - 5) ° C. The reaction temperature of the solid-state polymerization may be changed in stages, and the final reaction temperature of the solid-state polymerization is preferably from (melting point - 90) ° C to (melting point - 10) ° C, and more preferably from (melting point - 80) ° C to (melting point - 15) ° C. The solid-state polymerization may be performed with stirring, or may be performed in a stationary state without stirring.

[0044] The polymerization reactor is not particularly limited, but a reactor generally used for reactions of high-viscosity fluids is preferably used. Examples of such reactors include stirred tank-type polymerization reactors having stirrers with stirring blades of various shapes, such as anchor-type, multi-stage-type, spiral belt-type, and spiral shaft-type, or modified versions of these, as well as mixing devices generally used for kneading resins, such as kneaders, roll mills, and Banbury mixers.

[0045] (Molded Article) The molded article according to the present invention contains the liquid crystal polyester resin of the present invention, and may further contain other liquid crystal polyester resins other than the liquid crystal polyester resin of the present invention, other resins other than the liquid crystal polyester resin, and fillers. The content of the resin components in the molded article (the liquid crystal polyester resin of the present invention, the other liquid crystal polyester resins other than the liquid crystal polyester resin of the present invention, and the other resins other than the liquid crystal polyester resin) is preferably 30% by mass or more and 99% by mass or less, more preferably 40% by mass or more and 95% by mass or less, even more preferably 50% by mass or more and 90% by mass or less, and even more preferably 55% by mass or more and 85% by mass or less, based on the total amount of the molded article.

[0046] (Filler) Examples of the filler include carbon fiber, graphite, glass fiber, talc, mica, glass flake, clay, sericite, calcium carbonate, calcium sulfate, calcium silicate, silica, alumina, aluminum hydroxide, calcium hydroxide, graphite, potassium titanate, titanium oxide, fluorocarbon resin fiber, fluorocarbon resin, barium sulfate, various whiskers, etc. These fillers may be used alone or in combination of two or more.

[0047] The content of the filler in the molded article is preferably 1% by mass or more and 70% by mass or less, more preferably 5% by mass or more and 60% by mass or less, even more preferably 10% by mass or more and 50% by mass or less, and even more preferably 15% by mass or more and 45% by mass or less, based on the total amount of the molded article. When two or more fillers are contained, it is preferable that the total content thereof is within the above range. If the content of the filler in the molded article is within the above range, a molded article having better mechanical properties can be obtained, which is preferable.

[0048] (Other Liquid Crystalline Polyester Resins Other Than the Liquid Crystalline Polyester Resin of the Present Invention) The other liquid crystal polyester resin is not particularly limited as long as it is a liquid crystal polyester resin other than the liquid crystal polyester resin of the present invention, and conventionally known liquid crystal polyester resins can be used. A preferred embodiment of the other liquid crystal polyester resin is, for example, a liquid crystal polyester resin having structural units derived from a hydroxycarboxylic acid. A particularly preferred embodiment is a liquid crystal polyester resin containing 65 to 80 mol % (preferably 70 to 75 mol %) of p-hydroxybenzoic acid and 20 to 35 mol % (preferably 25 to 30 mol %) of 6-hydroxy-2-naphthoic acid. Another preferred embodiment is, for example, a liquid crystal polyester resin that, in addition to having structural units derived from a hydroxycarboxylic acid, further contains at least one structural unit derived from an aromatic dicarboxylic acid and a structural unit derived from an aromatic diol. A particularly preferred embodiment is a liquid crystal polyester resin containing 60 to 80 mol% (preferably 65 to 75 mol%) of p-hydroxybenzoic acid, 1 to 5 mol% of 6-hydroxy-2-naphthoic acid, 0 to 20 mol% (preferably 1 to 15 mol%) of structural units derived from an aromatic dicarboxylic acid, and 0 to 20 mol% (preferably 1 to 15 mol%) of structural units derived from an aromatic diol. Examples of structural units derived from an aromatic dicarboxylic acid include structural units derived from at least one of 4,4'-dihydroxybiphenyl and hydroquinone. Examples of structural units derived from an aromatic diol include structural units derived from at least one of terephthalic acid, isophthalic acid, and 4'-hydroxy-4-biphenylcarboxylic acid. The compositional ratio of each structural unit is not limited to the preferred embodiment described above and can be adjusted as appropriate. The other liquid crystal polyester resins may be used alone or in combination of two or more.

[0049] The content of other liquid crystal polyester resins other than the liquid crystal polyester resin of the present invention in the molded product is preferably 90 parts by mass or less, more preferably 75 parts by mass or less, and even more preferably 50 parts by mass or less, relative to 100 parts by mass of the total of the liquid crystal polyester resin of the present invention and the other liquid crystal polyester resins, and the lower limit may be 1 part by mass or more, 3 parts by mass or more, or 5 parts by mass or more.

[0050] (Resins other than liquid crystal polyester resins) The molded article according to the present invention may contain resins other than liquid crystal polyester resins, as long as they do not deviate from the spirit of the present invention. Examples of other resins include polyester resins such as polyethylene terephthalate, polyethylene naphthalate, polyarylate, polycyclohexylene dimethylene terephthalate, and polybutylene terephthalate, polyolefin resins such as polyethylene and polypropylene, cycloolefin polymers, vinyl resins such as polyvinyl chloride, (meth)acrylic resins such as polyacrylate, polymethacrylate, and polymethyl methacrylate, imide resins such as polyphenylene ether resins, polyacetal resins, polyamide resins, polyimides, and polyetherimides, polystyrene resins such as polystyrene, high-impact polystyrene, AS resin, and ABS resin, thermosetting resins such as epoxy resins, cellulose resins, polyether ether ketone resins, fluororesins, and polycarbonate resins. These other resins may be used alone or in combination of two or more.

[0051] The upper limit of the content of other resins other than the liquid crystal polyester resin in the molded product is preferably 10 parts by mass or less, more preferably 5 parts by mass or less, relative to 100 parts by mass of the total of the liquid crystal polyester resin of the present invention and the other liquid crystal polyester resin.

[0052] (Other Additives) The molded article according to the present invention may contain other additives, such as colorants, dispersants, plasticizers, antioxidants, curing agents, flame retardants, heat stabilizers, UV absorbers, antistatic agents, and surfactants, within the scope of the present invention. These other additives may be used alone or in combination of two or more.

[0053] The shape of the molded article is not particularly limited and may be changed appropriately depending on the application, and examples of the shape of the molded article include fiber, plate, sheet, and rod.

[0054] The molded article according to the present invention can be produced by a conventionally known molding method using a resin composition containing a liquid crystal polyester resin and, if desired, a filler or other resins, etc. The molding method may be, for example, any of melt spinning, solution spinning, injection molding, compression molding, injection compression molding, calendar molding, punch molding, etc.

[0055] (Electrical / Electronic Component) The electrical / electronic component according to the present invention comprises a molded article (e.g., a fibrous molded article or an injection-molded article) containing a liquid crystal polyester resin. Examples of electrical / electronic components comprising the molded article include antennas used in electronic devices and communication devices such as ETC, GPS, wireless LAN, and mobile phones, high-speed transmission connectors, CPU sockets, circuit boards, flexible printed circuit boards (FPC), laminated circuit boards, millimeter-wave and quasi-millimeter-wave radars such as collision prevention radars, RFID tags, capacitors, inverter components, cable covering materials, insulating materials for secondary batteries such as lithium-ion batteries, and speaker diaphragms.

[0056] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0057] <Liquid Crystal Polyester Resin Production Example 1> (Example 1-1) 25 mol % of p-hydroxybenzoic acid (HBA), 73 mol % of 6-hydroxy-2-naphthoic acid (HNA), and 2 mol % of m-hydroxybenzoic acid (mHBA) were added to a polymerization vessel equipped with a stirring blade, and further, 0.50 mol % of terephthalic acid (TPA) was added relative to the total amount (100 mol %) of these hydroxycarboxylic acids. Potassium acetate was charged as a catalyst, and the polymerization vessel was subjected to a vacuum-nitrogen injection cycle three times. Thereafter, acetic anhydride (1.08 molar equivalents relative to the hydroxyl groups) was further added, and the temperature was raised to 160°C, and an acetylation reaction was carried out under reflux for 1.5 hours.

[0058] After completion of acetylation, the polymerization vessel, which had been left in an acetic acid distillation state, was heated at a rate of 0.6°C / min until the melting zone temperature in the vessel reached 313°C. The melt polymerization reaction was then terminated when the amount of distilled acetic acid exceeded 95% by mass of the theoretical outflow amount. The polymer was then extracted and cooled to solidify. The resulting polymer was pulverized to a size that could pass through a 2.0 mm mesh sieve to obtain a polymer. Next, the resulting polymer was heated in a Nato oven (trade name: DN411I) manufactured by Yamato Scientific Co., Ltd. under nitrogen gas flow at a rate of 30 L / min or more to carry out solid-state polymerization. In the solid-state polymerization, the temperature was raised from room temperature to 250°C, held at 250°C for 2 hours, and then raised to 270°C and held there for 1 hour. The "250-2h, 270-1h" solid-state polymerization conditions listed in Table 1 indicate that solid-state polymerization was carried out at 250°C for 2 hours and at 270°C for 1 hour. Furthermore, the temperature was switched at each step in the solid-state polymerization as quickly as possible within the capabilities of the equipment.

[0059] The polymer was then allowed to cool naturally at room temperature to obtain a polyester resin of the present invention. The polyester resin was heated and melted on the heated stage of a polarizing microscope (product name: DS-Ri2) manufactured by Nikon Corporation equipped with a hot stage for a microscope (product name: 10083L) manufactured by Japan High-Tech Co., Ltd., and liquid crystallinity was confirmed based on the presence or absence of optical anisotropy.

[0060] (Example 1-2) A polyester resin was obtained in the same manner as in Example 1-1, except that the reaction stop temperature of the melt polymerization was changed to 296°C and the conditions of the solid-state polymerization were changed as follows: In the solid-state polymerization, the temperature was raised from room temperature to 250°C and maintained for 2 hours, then raised to 270°C and maintained for 2 hours, and then raised to 290°C and maintained for 1 hour. Next, the liquid crystallinity of the polyester resin was confirmed in the same manner as above.

[0061] (Example 1-3) A polyester resin was obtained in the same manner as in Example 1-1, except that the reaction termination temperature of the melt polymerization was changed to 320°C and the conditions of the solid-state polymerization were changed as follows: In the solid-state polymerization, the temperature was raised from room temperature to 230°C and maintained for 1 hour, then raised to 250°C and maintained for 1 hour, and then raised to 270°C and maintained for 1.5 hours. Next, the liquid crystallinity of the polyester resin was confirmed in the same manner as above.

[0062] (Comparative Example 1-1) After acetylation was completed in the same manner as in Example 1-1, the temperature was raised until the melting zone temperature in the tank reached 350°C, and then the pressure was reduced to 10 hPa over 30 minutes while maintaining the temperature constant. The power consumption of the stirring motor driving the stirring of the reaction system was monitored, and the polymerization reaction was terminated when the power consumption amount corresponding to a predetermined torque load indicating that the target viscosity had been reached was reached. Furthermore, a polyester resin was obtained in the same manner as in Example 1-1, except that the solid-state polymerization conditions were changed as follows. In the solid-state polymerization, the temperature was raised from room temperature to 270°C and maintained for 0.95 hours. Next, the liquid crystallinity of the polyester resin was confirmed in the same manner as above.

[0063] (Comparative Example 1-2) A polyester resin was obtained in the same manner as in Example 1-1, except that the reaction termination temperature of the melt polymerization was changed to 350°C and the conditions of the solid-state polymerization were changed as follows: In the solid-state polymerization, the temperature was raised from room temperature to 250°C and maintained at that temperature for 2 hours, and then raised to 270°C and maintained at that temperature for 0.5 hours. Next, the liquid crystallinity of the polyester resin was confirmed in the same manner as above.

[0064] (Example 2-1) A polyester resin was obtained in the same manner as in Example 1-1, except that TPA was not added and the solid-state polymerization conditions were changed as follows. In the solid-state polymerization, the temperature was raised from room temperature to 250°C and maintained for 4 hours. Next, the liquid crystallinity of the polyester resin was confirmed in the same manner as above.

[0065] (Comparative Example 2-1) A polyester resin was obtained in the same manner as in Comparative Example 1-1, except that TPA was not added and the solid-state polymerization conditions were changed as follows. In the solid-state polymerization, the temperature was raised from room temperature to 290°C and maintained at that temperature for 1 hour. Next, the liquid crystallinity of the polyester resin was confirmed in the same manner as above.

[0066] Example 3-1 A polyester resin was obtained in the same manner as in Example 1-1, except that no TPA was added, but 1 mol % of 4,4'-dihydroxybiphenyl (BP) was added, and the solid-state polymerization conditions were changed as follows: In the solid-state polymerization, the temperature was raised from room temperature to 250°C and maintained for 2 hours, and then raised to 280°C and maintained for 2 hours. Next, the liquid crystallinity of the polyester resin was confirmed in the same manner as above.

[0067] Comparative Example 3-1 A polyester resin was obtained in the same manner as in Comparative Example 1-1, except that no TPA was added, 1 mol % of 4,4'-dihydroxybiphenyl (BP) was added, and further, solid-state polymerization was not performed. Next, the liquid crystallinity of the polyester resin was confirmed in the same manner as above.

[0068] Example 4-1 A polyester resin was obtained in the same manner as in Example 1-1, except that no TPA was added, 1 mol % of hydroquinone (HQ) was added, and the solid-state polymerization conditions were changed as follows. In the solid-state polymerization, the temperature was raised from room temperature to 250°C and maintained for 4.5 hours. Next, the liquid crystallinity of the polyester resin was confirmed in the same manner as above.

[0069] (Comparative Example 4-1) A polyester resin was obtained in the same manner as in Comparative Example 1-1, except that no TPA was added, 1 mol% of hydroquinone (HQ) was added, and further, solid-state polymerization was not performed. Next, the liquid crystallinity of the polyester resin was confirmed in the same manner as above.

[0070] (Reference Example 1-1) The monomer charge was changed to 73 mol% HBA and 27 mol% HNA, and after acetylation was completed, the temperature was raised until the melting zone temperature in the tank reached 322°C, and then the pressure was reduced to 10 hPa over 30 minutes while maintaining the temperature constant. The polymerization reaction was terminated at the same time point as in Comparative Example 1-1, and a polyester resin was obtained in the same manner as in Example 1-1, except that solid-state polymerization was not performed. Next, the liquid crystallinity of the polyester resin was confirmed in the same manner as above.

[0071] (Reference Example 1-2) A polyester resin was obtained in the same manner as in Example 1-1, except that the monomer charge was changed to 27 mol% HBA and 73 mol% HNA, the reaction termination temperature of the melt polymerization was changed to 304°C, and the conditions of the solid-state polymerization were changed as follows. In the solid-state polymerization, the temperature was raised from room temperature to 270°C and maintained for 1 hour. Next, the liquid crystallinity of the polyester resin was confirmed in the same manner as above.

[0072] Table 1 shows the composition ratios (mol %) of the structural units of the polyester resins produced in the above Examples, Comparative Examples, and Reference Examples, as well as the polymerization conditions.

[0073] <Performance Evaluation 1 of Liquid Crystal Polyester Resin> <Measurement of Melting Point> The melting points of the liquid crystal polyester resins obtained in the examples and comparative examples were measured using a differential scanning calorimeter (DSC) manufactured by Hitachi High-Tech Science Corporation. First, in accordance with JIS-7121, the liquid crystal polyester resin was heated from room temperature to 360 ° C. at a heating rate of 10 ° C. / min to completely melt, and then cooled to 30 ° C. at a rate of 10 ° C. / min. The apex of the exothermic peak obtained when the temperature was lowered to 30 ° C. at a rate of 10 ° C. / min was taken as the crystallization point (Tc), and the apex of the endothermic peak obtained when the temperature was further increased to 360 ° C. at a rate of 10 ° C. / min was taken as the melting point (Tm). The melting point (Tm) and crystallization point (Tc) are shown in Table 1.

[0074] <Measurement of Melt Viscosity> The melt viscosity (Pa s) of the liquid crystal polyester resins obtained in the examples and comparative examples was measured in accordance with JIS K7199 using a capillary rheometer viscometer (Capillograph 1D, manufactured by Toyo Seiki Seisakusho Co., Ltd.) and a capillary having an inner diameter of 1 mm and a length of 40 mm (L / D = 40) at the temperature and shear rate of 1000 / s shown in Table 1. The measurement results are shown in Table 1.

[0075]

[0076] <Performance Evaluation 2 of Liquid Crystalline Polyester Resin> <Evaluation of Sequence State of Main Chain> The liquid crystal polyester resins of Reference Examples 1 and 2, Examples 1-1 to 1-3, and Comparative Example 1-1 obtained above were evaluated under the following conditions. １３ C-NMR measurement was carried out to evaluate the sequence state of the main chain. １３ The C-NMR spectra are shown in Figures 1 to 6. １３ C-NMR conditions) Measurement device: JEOL ECZ500R-M3 500 MHz NMR Detector: Φ10 mm Measurement conditions 13C: (1H-complete decoupling method) Number of accumulations: 20,000 Waiting time: 2 seconds Measurement temperature: 100°C Solvent: pentafluorophenol Liquid crystal polyester resin concentration: 3.5 mass% Reference chemical shift: 134.86 ppm

[0077] First, the liquid crystal polyester resins obtained in Reference Example 1 (composition: HBA73 / HNA27) and Reference Example 2 (composition: HBA27 / HNA73) were used. １３ In the C-NMR spectrum, four peaks were confirmed at the chemical shift value (165-175 ppm) of the carbonyl carbon (COO) of the ester, and the peaks derived from the ester bond of the same or different hydroxycarboxylic acids were identified based on the relationship between each chemical shift and their integral ratio. The ester bond forms of the hydroxycarboxylic acids include "HBA-COO-HBA" (same type), "HBA-COO-HNA (HNA-COO-HBA)" (different type), and "HNA-COO-HNA" (same type). The identification results are shown in Table 2.

[0078] Next, the liquid crystal polyester resins (composition: HBA25 / HNA73 / mHBA2) obtained in Examples 1-1 to 1-3 and Comparative Example 1-1 were used. １３ In the C-NMR spectrum, the peak present at the chemical shift value (165-175 ppm) of the carbonyl carbon (COO) of the ester was confirmed in the same manner as above, and the peak derived from the ester bond involving mHBA was identified from the order and equivalence of the integral ratio. The ester bond type involving mHBA includes "HBA-COO-mHBA (mHBA-COO-HBA)" (heterogeneous), "HNA-COO-mHBA (mHBA-COO-HNA)" (heterogeneous), and "mHBA-COO-mHBA" (homogeneous), but it was presumed that no peak appeared in "mHBA-COO-mHBA" (homogeneous) due to the low composition ratio of mHBA. The identification results are shown in Table 2.

[0079]

[0080] Each bonding mode was quantified from the integral ratio of the peaks present at the corresponding chemical shifts shown in Table 2 above, and the parameters of the following formula (I) were calculated. Even liquid crystal polyesters polymerized using the same type of monomer may be affected by the homopolymerization state, causing specific chemical shifts to become insignificant. Furthermore, depending on the measurement environment, the positions of individual chemical shifts may show slight shifts. Therefore, the positions of the chemical shifts (peak tops) in Table 2 are merely representative values ​​based on the measurement conditions. Specifically, based on the above mathematical formula (I), the proportion of the ester bond between hydroxycarboxylic acids with the largest constituent amount ("HNA-COO-HNA" in Examples 1-1 to 1-3, Comparative Example 1-1, and Reference Example 1-2, and "HBA-COO-HBA" in Reference Example 1-1) among all ester bonds (all carbonyl carbons) present in the liquid crystal polyester resin was calculated. This indicates the proportion of "self-linkages" of hydroxycarboxylic acids with the largest constituent amount that have the greatest impact on physical properties. The calculation results are shown in Table 3. In Table 3, the peak (c) corresponds to the carbonyl of the "HNA-COO-HNA" bond, and the peak (a) corresponds to "HBA-COO-HBA". Therefore, the proportion of "self-linking" of the hydroxycarboxylic acid having the largest constituent amount in Table 3 is a value obtained by dividing the integral ratio of the peak of (c) by the total integral ratio of all ester bonds in the range of 165 to 175 ppm in Examples 1-1 to 1-3, Comparative Example 1-1, and Reference Example 1-2, and is a value obtained by dividing the integral ratio of the peak of (a) by the total integral ratio of all ester bonds in the range of 165 to 175 ppm in Reference Example 1-1.

[0081]

[0082] The results in Table 3 show that by changing the polymerization conditions of the liquid crystalline polyester resin (particularly the reaction termination temperature of the melt polymerization), it is possible to control the amount of "self-linking" of the hydroxycarboxylic acid with the largest constituent amount, which has the greatest impact on physical properties. Specifically, by terminating the melt polymerization within a specific temperature range, it was possible to suppress the "self-linking" of the hydroxycarboxylic acid with the largest constituent amount. This demonstrated the effect of significantly increasing the melting point of liquid crystalline polyesters with the same monomer composition and equivalent melt viscosities under the same conditions, i.e., the same degree of polymerization. The obtained liquid crystalline polyester resins were separately hydrolyzed, and proton NMR measurements of the hydrolysates confirmed that all Examples and Comparative Examples had the monomer composition according to the feed ratio. Furthermore, using the integrated values ​​of Figures 1 and 2, the proportions of all ester bonds present in the liquid crystalline polyester resins of the "self-linking" of the hydroxycarboxylic acid with the largest constituent amount in Reference Example 1 and Reference Example 2 (HBA-COO-HBA in Reference Example 1 and HNA-COO-HNA in Reference Example 2) were 52% and 51%, respectively. From this, it was confirmed that the use of three or more hydroxycarboxylic acids in the present invention could reduce the "self-linking" of the most abundant hydroxycarboxylic acid.

[0083] <Performance Evaluation 3 of Liquid Crystal Polyester Resin> <Preparation of Bending Test Piece> The liquid crystal polyester resins obtained in Example 1-1 and Comparative Example 1-1 were heated and melted (mold temperature 80°C) at a melting point +20°C, and injection molded to prepare bending test pieces of 80 mm x 12 mm x 2 mm (thickness).

[0084] <Measurement of Deflection Temperature Under Load (DTUL)> Using the bending test specimens prepared above, the deflection temperature under load (DTUL) was measured at a load of 1.8 MPa in accordance with ASTM D648. The measurement was carried out three times independently, and the average value of the three measurements is shown in Table 4. A higher deflection temperature under load indicates better practical heat resistance.

[0085] <Measurement of Izod impact strength> The bending test piece prepared above was used to measure the Izod impact strength (kJ / m) using an impact tester (manufactured by Toyo Seiki Co., Ltd., model number: Izod impact tester No. 556) in accordance with ASTM D256 under the conditions of room temperature, hammer 5.5 J, and no notch. ２ The measurement was carried out five times independently, and the average values ​​of the five measurements are shown in Table 4.

[0086] <Measurement of Mechanical Strength> Using the bending test specimens prepared above, the flexural modulus (GPa), flexural strength (MPa), and flexural elongation (%) were measured at room temperature under the conditions of R = 50 mm, a support distance of 50 mm, and a test speed of 2.0 mm / min using a universal testing machine (manufactured by Toyo Seiki Co., Ltd., model number: Strograph VG) in accordance with JIS K 7171. The measurements were performed three times independently, and the average values ​​of the three measurements are shown in Table 4.

[0087]

[0088] As shown in Table 4, the liquid crystal polyester resin of Example 1, in which the ratio of ester bonds between the hydroxycarboxylic acids with the largest constituent amount was controlled, had a higher deflection temperature under load and improved practical heat resistance compared to the liquid crystal polyester resin of Comparative Example 1. Furthermore, the Izod impact strength and flexural strength of Example 1-1 and Comparative Example 1-1 were both equivalent. From this, the increase in deflection temperature under load in Example 1-1 is largely due to the increase in the thermal properties of the polymer (increase in melting point) achieved by realizing a favorable self-linking state.

Claims

1. A liquid crystal polyester resin containing structural units derived from three or more hydroxycarboxylic acids, characterized in that the liquid crystal polyester resin satisfies the following condition: the proportion of ester bonds formed between the hydroxycarboxylic acid that is the most abundant structural unit among the structural units derived from the three or more hydroxycarboxylic acids and the same hydroxycarboxylic acid is 12% or more and 60% or less of the total ester bonds present in the liquid crystal polyester resin.

2. The liquid crystal polyester according to claim 1, wherein the compositional ratio of the constituent units derived from the three or more kinds of hydroxycarboxylic acids is 50 mol % or more based on the total constituent units of the liquid crystal polyester resin.

3. The liquid crystal polyester resin according to claim 1, wherein the composition ratio of the structural unit having the largest number among the structural units derived from the three or more hydroxycarboxylic acids is 40 mol % or more and 98 mol % or less relative to all structural units derived from the three or more hydroxycarboxylic acids.

4. The liquid crystal polyester resin according to claim 1, wherein the composition ratio of the second most abundant structural unit among the structural units derived from the three or more hydroxycarboxylic acids is 1 mol % or more and 40 mol % or less relative to all structural units derived from the three or more hydroxycarboxylic acids.

5. The liquid crystal polyester resin according to claim 1, wherein the composition ratio of the third most abundant structural unit among the structural units derived from the three or more hydroxycarboxylic acids is 0.1 mol % or more and 20 mol % or less relative to the total structural units derived from the three or more hydroxycarboxylic acids.

6. The liquid crystal polyester resin according to claim 3, wherein the most abundant structural unit among the structural units derived from the three or more hydroxycarboxylic acids is a structural unit derived from p-hydroxybenzoic acid or a structural unit derived from 6-hydroxy-2-naphthoic acid.

7. The liquid crystal polyester resin according to claim 4, wherein the second most abundant structural unit among the structural units derived from the three or more hydroxycarboxylic acids is a structural unit derived from p-hydroxybenzoic acid or a structural unit derived from 6-hydroxy-2-naphthoic acid.

8. The liquid crystal polyester resin according to claim 1, wherein the melting point of the liquid crystal polyester resin is 270°C or higher and 370°C or lower.

9. The liquid crystal polyester resin according to claim 1, which has a melt viscosity of 1 Pa·s or more measured at a temperature of from the melting point of the liquid crystal polyester resin to the melting point + 30° C. or more and at a shear rate of 1000 / s.

10. The liquid crystal polyester resin according to claim 1, wherein the liquid crystal polyester resin has a deflection temperature under load of 180° C. or higher.

11. A fibrous molded article comprising the liquid crystal polyester resin according to any one of claims 1 to 10.

12. A sheet-like molded product comprising the liquid crystal polyester resin according to any one of claims 1 to 10.

13. An injection-molded article comprising the liquid crystal polyester resin according to any one of claims 1 to 10.

14. An electric / electronic component comprising the molded article according to claim 11.

15. An electric / electronic component comprising the molded article according to claim 12.

16. An electric / electronic component comprising the molded article according to claim 13.