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

Abstract

[Problem] To provide a liquid-crystal polyester resin which has a low permittivity and a low dielectric loss tangent and which can have improved practical heat resistance and can be inhibited from outgassing or forming foreign matters or the like. [Solution] A liquid-crystal polyester resin according to the present invention contains constituent units derived from hydroxycarboxylic acids in an amount of 90 mol% or larger with respect to all the constituent units, and is characterized in that: the constituent units derived from hydroxycarboxylic acids comprise a constituent unit (A) derived from p-hydroxybenzoic acid, a constituent unit (B) derived from 6-hydroxy-2-naphthoic acid, and a constituent unit (C) derived from a hydroxycarboxylic acid which is neither the constituent unit (A) nor the constituent unit (B), the constituent unit (C) being a constituent unit derived from at least one acid selected from the group consisting of m-hydroxybenzoic acid, 6-hydroxynicotinic acid, and 4'-hydroxy-4-biphenylcarboxylic acid; the liquid-crystal polyester resin further contains a constituent unit (D) derived from a dicarboxylic acid and / or a constituent unit (E) derived from a diol; the proportions (mol%) of the constituent units (A) to (E) satisfy the requirements shown by the following formulae 10 mol%≤[constituent unit (A)]≤30 mol%, 60 mol%≤[constituent unit (B)]≤80 mol%, 0.1 mol%≤[constituent unit (C)]≤10 mol%, and 0.1 mol%≤[(constituent unit (D))+(constituent unit (E))]≤2.0 mol%; and the liquid-crystal polyester resin has a melt viscosity, as measured under the conditions of 350°C and a shear rate of 1,000 / s, of 25 Pa·s or greater.

Description

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

[0001] The present invention relates to a liquid crystal polyester resin, and more particularly to a liquid crystal polyester resin having a low dielectric constant and a low dielectric loss tangent, a molded article containing the liquid crystal polyester resin, and an electric / electronic part including the molded article.

[0002] In recent years, with the increase in the amount of information and communication in the field of communication, the use of high frequency band signals in electronic devices and communication devices has increased. ９ Gigahertz (GHz) band signals are widely used. For example, GHz band signals are used in the automotive field. Specifically, millimeter-wave radar and quasi-millimeter-wave radar installed in automobiles for collision prevention purposes use high frequencies of 76 to 79 GHz and 24 GHz, respectively, and these frequencies are expected to become even more widespread in the future.

[0003] However, as the frequency of signals used increases, a deterioration in the quality of output signals, which can lead to erroneous recognition of information, i.e., an increase in transmission loss, becomes a problem. Transmission loss consists of conductor loss due to conductors and dielectric loss due to insulating resins that constitute electrical and electronic components such as circuit boards in electronic devices and communication devices. Conductor loss is proportional to the half power of the frequency used, while dielectric loss is proportional to the first power of the frequency. Therefore, the impact of dielectric loss becomes significant in high frequency bands, particularly in the GHz band. Furthermore, since dielectric loss increases in proportion to the half power of the resin's dielectric constant and the first power of its dielectric loss tangent, there is a need to develop resins with low dielectric constants, particularly low dielectric loss tangents, which have a significant impact on reducing dielectric loss, in order to prevent information degradation.

[0004] Typical molecular designs of liquid crystal polyester resins, known as insulating resins, include type II liquid crystal polyester resins composed solely of aromatic hydroxycarboxylic acid, and type I liquid crystal polyester resins containing a certain amount of aromatic diol / aromatic dicarboxylic acid as constituent components in addition to aromatic hydroxycarboxylic acid. Type I liquid crystal polyester resins generally have a higher melting point than type II liquid crystal polyester resins and also tend to have higher practical heat resistance as components. On the other hand, as reported in Non-Patent Document 1, type II liquid crystal polyester resins have a high degree of freedom in designing the higher-order structure during processing, such as the relaxation of the orientation of liquid crystal polyester resins, and are excellent in processability and designability as materials.

[0005] Under these circumstances, Patent Document 1 reports a liquid crystal polyester resin that is injection molding adaptable and aims to have a low dielectric loss tangent, the liquid crystal polyester resin containing aromatic hydroxycarboxylic acids as the main constituent elements, and among these, 6-hydroxy-2-naphthoic acid as the main monomer.

[0006] Liquid crystal polyester resin is known to have a problem of blisters forming on the surface of molded articles during molding. These blisters are caused by air entrapment during molding, residual gases such as acetic anhydride used in polymerization and acetic acid generated during polymerization, as well as by-product gases generated during the polycondensation reaction between the hydroxyl and carboxyl terminals of the liquid crystal polyester resin during molding.

[0007] To address these technical issues, Patent Document 2 discloses a method for reducing decomposition gases by adding 3 mol % or less of an aromatic diol or aromatic dicarboxylic acid to an aromatic hydroxycarboxylic acid-based liquid crystal polyester resin to enhance thermal stability.

[0008] JP 2017-179127 A International Publication No. 2018 / 139393

[0009] Macromolecules 2007, 40, 2524-2531

[0010] In recent years, the volume of information communication has continued to increase rapidly, and the frequency of signals used has become higher. Furthermore, in order to prevent transmission delays, emphasis is being placed not only on low dielectric loss tangent but also on low dielectric constant. From this perspective, Patent Document 1 was able to significantly reduce the dielectric loss tangent, but the dielectric constant tended to be higher than that of general-purpose liquid crystal polyester resins.

[0011] Furthermore, in the processing of liquid crystal polyester resins after molding, such as processing with molten solder or thermocompression bonding with metal, the processing is often performed at temperatures below the melting point of the liquid crystal polyester resin but sufficiently higher than the glass transition point. It is practically important that the liquid crystal polyester resin used does not deform during such high-temperature processing after molding, and the deflection temperature under load is used as a method for evaluating this ability. In this evaluation, the liquid crystal polyester resin described in Patent Document 1 has a problem in that it has low heat resistance and is therefore limited in its applicability to practical processing methods.

[0012] Furthermore, when three specific aromatic hydroxycarboxylic acids were used, further evaluation of heat resistance during processing revealed issues with melt processing and post-molding heat resistance. Specifically, these issues included gas generation and black impurities. Type II liquid crystal polyester resins composed of three aromatic hydroxycarboxylic acids generated outgassing, which caused blisters, and black impurities such as charcoal during melt molding. Furthermore, even when the molded product was heated below its melting point, the number of impurities tended to increase. The generation of outgassing and impurities was a significant issue, as it not only resulted in poor appearance but also reduced material properties.

[0013] Therefore, in the present invention, we have discovered that by using three aromatic hydroxycarboxylic acids in a type II liquid crystal polyester resin primarily composed of 2,6-hydroxynaphthoic acid and exceeding a specific viscosity range under high temperature conditions, we can reduce both the dielectric constant and the dielectric loss tangent. This has enabled us to reduce the parameter "the product of the 1 / 2 power of the dielectric constant and the dielectric loss tangent," which estimates the magnitude of dielectric loss when an electric substrate is produced using a dielectric whose dielectric constant and dielectric loss have been measured. Furthermore, we have discovered that a wholly aromatic liquid crystal polyester can be obtained that also has excellent practical heat resistance, as evaluated by deflection temperature under load.

[0014] As described above, an object of the present invention is to provide a liquid crystalline polyester resin that has a low dielectric constant and a low dielectric loss tangent, while improving practical heat resistance and suppressing the generation of outgassing and foreign matter, etc. Another object of the present invention is to provide a molded article containing this liquid crystalline polyester resin and an electric / electronic part including the molded article.

[0015] That is, the present invention provides the following inventions: [1] A liquid crystal polyester resin comprising 90 mol% or more of all structural units that are derived from hydroxycarboxylic acids, wherein the structural units derived from hydroxycarboxylic acids include structural units (A) derived from p-hydroxybenzoic acid, structural units (B) derived from 6-hydroxy-2-naphthoic acid, and structural units (C) derived from hydroxycarboxylic acids other than the structural units (A) and (B), and the structural units (C) are structural units derived from at least one selected from the group consisting of m-hydroxybenzoic acid, 6-hydroxynicotinic acid, and 4'-hydroxy-4-biphenylcarboxylic acid, wherein the liquid crystal polyester resin further comprises at least one of structural units (D) derived from dicarboxylic acids and structural units (E) derived from diols, and wherein the compositional ratios (mol%) of the structural units (A) to (E) satisfy the following conditions: 10 mol%≦structural unit (A)≦30 mol%, 60 mol%≦structural unit (B)≦80 mol%, and 0.1 mol%≦structural unit (C)≦10 mol%. A liquid crystal polyester resin, characterized in that: 0.1 mol %≦structural unit (D) + structural unit (E)≦2.0 mol %, and the liquid crystal polyester resin has a melt viscosity of 25 Pa s or more measured at 350°C and a shear rate of 1000 / s. [2] A liquid crystal polyester resin, characterized in that: the melt viscosity of the liquid crystal polyester resin is 25 Pa s or more measured at a shear rate of 1000 / s. －３ [3] The liquid crystal polyester resin according to [1], wherein the product of the dielectric constant to the half power and the dielectric loss tangent at a measurement frequency of 10 GHz is less than 1.70 × 10 －３The liquid crystal polyester resin according to [1] or [2], wherein the composition ratio (mol%) of the structural unit (C) satisfies the following condition: 0.1 mol%≦structural unit (C)≦6.0 mol%. [5] The liquid crystal polyester resin according to any of [1] to [4], wherein the structural unit (C) is a structural unit derived from m-hydroxybenzoic acid. [6] The liquid crystal polyester resin according to any of [1] to [5], wherein the liquid crystal polyester resin consists solely of structural units derived from hydroxycarboxylic acid and structural units (D) derived from dicarboxylic acid. [7] The liquid crystal polyester resin according to any of [1] to [6], wherein the composition ratio (mol%) of the structural unit (D) satisfies the following condition: 0.1 mol%≦structural unit (D)<1.0 mol%. [8] The liquid crystal polyester resin according to any of [1] to [6], wherein the composition ratio (mol%) of the structural unit (D) satisfies the following condition: 0. The liquid crystal polyester resin according to any one of [1] to [6], which satisfies the condition: mol%≦structural unit (D)<0.8 mol%. [9] The liquid crystal polyester resin according to any one of [1] to [8], wherein the structural unit (D) is a structural unit derived from terephthalic acid.

[10] The liquid crystal polyester resin according to any one of [1] to [9], wherein the melting point of the liquid crystal polyester resin is 230°C or higher.

[11] The liquid crystal polyester resin according to any one of [1] to

[10] , wherein the deflection temperature under load of the liquid crystal polyester resin is 220°C or higher.

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

[11] .

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

[11] .

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

[11] .

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

[12] .

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

[13] .

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

[14] .

[0016] According to the present invention, a liquid crystal polyester resin can be obtained that has a low dielectric constant and a low dielectric dissipation factor, while improving practical heat resistance and suppressing the generation of outgassing and foreign matter. Therefore, by using the liquid crystal polyester resin of the present invention, a molded product can be obtained that has a low dielectric constant and a low dielectric dissipation factor, while improving practical heat resistance and suppressing the generation of outgassing and foreign matter. Therefore, when used as a product, it is possible to prevent a decrease in the quality of output signals in electrical and electronic equipment and communication equipment that use high-frequency signals. Modes for carrying out the invention

[0017] (Liquid Crystal Polyester Resin) The liquid crystal polyester resin according to the present invention contains 90 mol% or more of all structural units derived from hydroxycarboxylic acid, and the structural units derived from hydroxycarboxylic acid include structural units (A) derived from p-hydroxybenzoic acid, structural units (B) derived from 6-hydroxy-2-naphthoic acid, and structural units (C) derived from a specific hydroxycarboxylic acid other than the structural units (A) and (B). Furthermore, the liquid crystal polyester resin contains at least one of structural units (D) derived from dicarboxylic acid and structural units (E) derived from diol. The liquid crystal polyester resin according to the present invention may be a single substance or a mixture (polymer blend).

[0018] In the present invention, by satisfying the following conditions for the composition ratio (mol %) of the structural units (A) to (E) in the liquid crystal polyester resin and satisfying a specific melt viscosity, it is possible to obtain a liquid crystal polyester resin that has a low dielectric constant and a low dielectric loss tangent, while also achieving improved practical heat resistance and suppressing the generation of outgassing and foreign matter. In particular, in the present invention, the addition of a specific aromatic diol or aromatic dicarboxylic acid can significantly suppress the generation of outgassing and foreign matter.

[0019] The lower limit of the melt viscosity of the liquid crystal polyester resin according to the present invention, measured at 350°C and a shear rate of 1000 / s, is 25 Pa·s or more, preferably 30 Pa·s or more, more preferably 35 Pa·s or more, even more preferably 40 Pa·s or more, and even more preferably 45 Pa·s or more. The upper limit is preferably 500 Pa·s or less, more preferably 300 Pa·s or less, even more preferably 200 Pa·s or less, and even more preferably 150 Pa·s or less. By setting the lower limit of the melt viscosity of the liquid crystal polyester resin according to the present invention within the above numerical range, a liquid crystal polyester resin can be obtained that has a specific viscosity range under high temperature conditions, has excellent moldability, reduced dielectric constant and dielectric loss tangent, and reduced blistering. Furthermore, by setting the upper limit of the melt viscosity of the liquid crystal polyester resin according to the present invention within the above numerical range, it becomes possible to process the resin using a wide range of melt molding methods, and to melt mold the resin under gentle conditions with reduced heating and applied pressure. In this specification, the melt viscosity of the liquid crystal polyester resin can be measured using a capillary rheometer viscometer in accordance with JIS K7199.

[0020] The upper limit of the dielectric loss tangent of the liquid crystal polyester resin according to the present invention at a measurement frequency of 10 GHz is preferably 1.0×10 －３ More preferably, it is 0.95×10 or less. －３ is preferably 0.90×10 or less. －３ is preferably 0.85×10 or less. －３or less. By setting the dielectric dissipation factor of the liquid crystal polyester resin according to the present invention within the above numerical range, it is possible to realize a dielectric dissipation factor that is half or less of that of liquid crystal polyester resins commonly used on the market. This also makes it possible to reduce the dielectric loss by half or less. Furthermore, the upper limit of the dielectric constant of the liquid crystal polyester resin according to the present invention at a measurement frequency of 10 GHz is preferably 3.70 or less, more preferably 3.60 or less, even more preferably 3.50 or less, and even more preferably 3.45 or less. By setting the dielectric constant of the liquid crystal polyester resin according to the present invention within the above numerical range, it is possible to reduce the dielectric constant even among liquid crystal polyesters with reduced dielectric dissipation factors, thereby further reducing the dielectric loss and suppressing transmission delay. Furthermore, the product of the dielectric constant to the half power and the dielectric dissipation factor at a measurement frequency of 10 GHz of the liquid crystal polyester resin according to the present invention is preferably 1.70 x 10 －３ More preferably, it is 1.65 × 10 or less. －３ is preferably 1.60×10 or less. －３ or less, and even more preferably 1.55×10 －３ By setting the dielectric loss tangent, dielectric constant, and the product of the dielectric loss tangent and the ½ power of the dielectric constant of the liquid crystal polyester resin according to the present invention within the above-mentioned numerical ranges, a molded article with reduced dielectric loss can be produced, and therefore, when used as a product, deterioration in the quality of output signals in electrical and electronic equipment and communication equipment that use high-frequency signals can be prevented. In this specification, the dielectric loss tangent and dielectric constant of the liquid crystal polyester resin at 10 GHz can be measured by the split post dielectric resonator method (SPDR method) using a network analyzer N5247A from Keysight Technologies, Inc., or the like, in an environment of a temperature of 23°C and a humidity of 50% rh.

[0021] The lower limit of the melting point of the liquid crystal polyester resin according to the present invention is, in consideration of heat resistance, preferably 230°C or higher, more preferably 280°C or higher, even more preferably 290°C or higher, still more preferably 295°C or higher, particularly preferably 300°C or higher, and most preferably 305°C or higher. The upper limit is not particularly limited, but may be 350°C or lower, 340°C or lower, 330°C or lower, 325°C or lower, or 320°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 even more preferably 245°C or higher. The upper limit is preferably 290°C or lower, more preferably 280°C or lower, even more preferably 275°C or lower, and even 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 numerical ranges, the heat resistance of molded articles produced using the liquid crystal polyester resin to heat processing can be improved, and molding can be easily performed without using special equipment. In this specification, the melting point and crystallization point of the liquid crystal polyester resin are values ​​measured using a differential scanning calorimeter (DSC). Specifically, 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 then lowered to 30°C at a rate of 10°C / min 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, taking into consideration practical heat resistance, is preferably 220°C or higher, more preferably 230°C or higher, even more preferably 240°C or higher, even more preferably 245°C or higher, and most preferably 250°C or higher. 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. By imparting these preferable practical heat resistances, the material can be processed without deformation during thermal processing (processing using molten solder or hot pressing) after melt processing of the liquid crystal polyester. In this specification, the deflection temperature under load (DTUL) of the liquid crystal polyester resin is a value measured edgewise (applied to a 12.5mm x 2mm surface) at a load of 0.45 MPa according to ASTM D648 using a bending test piece (80mm x 12.5mm 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] The liquid crystal polyester resin according to the present invention is characterized in that the composition ratios (mol %) of the structural units (A) to (E) satisfy the following conditions: 15 mol %≦structural unit (A)≦30 mol %, 60 mol %≦structural unit (B)≦80 mol %, 0.1 mol %≦structural unit (C)≦10 mol %, and 0.1 mol %≦structural unit (D)+structural unit (E)≦2.0 mol %, and preferably satisfies the following conditions: 15 mol %≦structural unit (A)≦30 mol %, 60 mol %≦structural unit (B)≦80 mol %, 0.1 mol %≦structural unit (C)≦6 mol %, and 0.1 mol %≦structural unit (D)+structural unit (E)≦2.0 mol %.

[0025] Furthermore, in the liquid crystal polyester resin according to the present invention, the composition ratios (mol %) of the structural units (A) to (D) preferably satisfy the following conditions: 15 mol %≦structural unit (A)≦30 mol % 60 mol %≦structural unit (B)≦80 mol % 0.1 mol %≦structural unit (C)≦10 mol % 0.1 mol %≦structural unit (D)<1.0 mol %. Also, the liquid crystal polyester resin preferably satisfies the following conditions: 15 mol %≦structural unit (A)≦30 mol % 60 mol %≦structural unit (B)≦80 mol % 0.1 mol %≦structural unit (C)≦10 mol % 0.1 mol %≦structural unit (D)<0.8 mol %. Also, the liquid crystal polyester resin preferably satisfies the following conditions: 15 mol %≦structural unit (A)≦30 mol % 60 mol %≦structural unit (B)≦80 mol % 0.1 mol %≦structural unit (C)≦6 mol %. It is preferable that the following conditions are satisfied: 0.1 mol%≦structural unit (D)<1.0 mol%. It is also preferable that the following conditions are satisfied: 15 mol%≦structural unit (A)≦30 mol% 60 mol%≦structural unit (B)≦80 mol% 0.1 mol%≦structural unit (C)≦6 mol% 0.1 mol%≦structural unit (D)<0.8 mol%.

[0026] Hereinafter, each of the structural units contained in the liquid crystal polyester resin according to the present invention will be described in detail.

[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] The composition ratio (mol%) of the structural unit (A) in the liquid crystal polyester resin is 10 mol% or more and 30 mol% or less. From the viewpoint of reducing the dielectric constant and dielectric loss tangent of the liquid crystal polyester resin, the lower limit of the composition ratio (mol%) of the structural unit (A) is preferably 13 mol% or more, more preferably 15 mol% or more, even more preferably 18 mol% or more, even more preferably 20 mol% or more, and the upper limit is preferably 29 mol% or less, more preferably 28 mol% or less, even more preferably 27 mol% or less, and even more preferably 26 mol% or less. By applying the composition ratio described above, it is possible to design heat resistance and excellent moldability.

[0029] (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.

[0030] The composition ratio (mol%) of the structural unit (B) in the liquid crystal polyester resin is 60 mol% or more and 80 mol% or less. From the viewpoint of reducing the dielectric constant and dielectric loss tangent of the liquid crystal polyester resin, the lower limit of the composition ratio (mol%) of the structural unit (B) is preferably 62 mol% or more, more preferably 64 mol% or more, even more preferably 66 mol% or more, even more preferably 68 mol% or more, and the upper limit is preferably 78 mol% or less, more preferably 76 mol% or less, even more preferably 75 mol% or less, and even more preferably 74 mol% or less. By applying the composition ratio described above, it is possible to achieve both suppression of the dielectric loss tangent and heat resistance.

[0031] (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 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.

[0032] The composition ratio (mol%) of the structural unit (C) in the liquid crystal polyester resin is 0.1 mol% or more and 10 mol% or less. From the viewpoint of reducing the dielectric constant and dielectric loss tangent of the liquid crystal polyester resin, the lower limit of the composition ratio (mol%) of the structural unit (C) is preferably 0.5 mol% or more, more preferably 1.0 mol% or more, even more preferably 1.5 mol% or more, and even more preferably 2.0 mol% or more, and the upper limit is preferably 8.0 mol% or less, more preferably 7.0 mol% or less, even more preferably 6.0 mol% or less, and even more preferably 3.0 mol% or less. By applying the above-described composition ratio, it is possible to maintain heat resistance, reduce the dielectric constant, and impart excellent moldability.

[0033] (Structural Unit (D) Derived from Dicarboxylic Acid) The structural unit (D) derived from a dicarboxylic acid is preferably a structural unit derived from a dicarboxylic acid represented by the following formula (1): Note that only one type of structural unit (D) may be included, or two or more types may be included.

[0034] In the above formula, Ar ３is 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.

[0035] Examples of monomers that provide the structural unit (D) include terephthalic acid (TPA), isophthalic acid (IPA), 2,6-naphthalenedicarboxylic acid (NADA), cyclohexanedicarboxylic acid (CHDA), and their acylates, ester derivatives, acid halides, etc. From the standpoints of reactivity and economic efficiency in procuring monomers, the structural unit (D) is preferably a structural unit derived from terephthalic acid.

[0036] (Diol-Derived Structural Unit (E)) The diol-derived structural unit (E) is preferably a diol-derived structural unit represented by the following formula (2): Only one type of structural unit (E) may be contained, or two or more types of structural units (E) may be contained.

[0037] In the above formula, Ar １is 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.

[0038] Examples of monomers that provide the structural unit (E) include 4,4'-dihydroxybiphenyl (BP), hydroquinone (HQ), methylhydroquinone (MeHQ), 4,4'-isopropylidenediphenol (BisPA), and acylated products, ester derivatives, and acid halides thereof.

[0039] The total composition ratio (mol%) of the structural unit (D) and the structural unit (E) in the liquid crystal polyester resin is 0.1 mol% or more and 2.0 mol% or less. From the viewpoint of reducing the dielectric constant and dielectric dissipation factor of the liquid crystal polyester resin, the lower limit of the total composition ratio (mol%) of the structural unit (D) and the structural unit (E) is preferably 0.2 mol% or more, more preferably 0.3 mol% or more, even more preferably 0.4 mol% or more, and even more preferably 0.5 mol% or more. By appropriately setting the lower limit of the structural unit (D), the effect of reducing foreign matter and outgassing and the rate of polymerization progress during solid-state polymerization can be favorably controlled. The upper limit is preferably 1.5 mol% or less, more preferably less than 1.0 mol%, even more preferably less than 0.8 mol%, and even more preferably less than 0.6 mol%. By appropriately setting the upper limit of the structural unit (D), excessive suppression of the polymerization progress during solid-state polymerization and the risk of deterioration in the thermal and mechanical properties of the liquid crystal polyester after polymerization can be reduced. In addition, it is possible to reduce the residual gas in the produced liquid crystal polyester and suppress the generation of by-product gas during melting, thereby achieving the effects of reducing foreign matter and reducing the occurrence of blisters. Note that the liquid crystal polyester resin does not need to contain the structural unit (E). When the liquid crystal polyester resin does not contain the structural unit (E), the preferred numerical range of the composition ratio of the structural unit (D) is the same as the preferred numerical range of the total composition ratio of the structural unit (D) and the structural unit (E).

[0040] (Method for Producing Liquid Crystal Polyester Resin) The liquid crystal polyester resin according to the present invention can be produced by a method (two-stage polymerization) comprising the steps of melt-polymerizing each of the monomers that provide the structural units (A) to (C), and at least one of the monomers that provide the structural unit (D) and the monomer that provides the structural unit (E) to obtain a polymer, and solid-state polymerizing the polymer to obtain a liquid crystal polyester resin.

[0041] 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.

[0042] The reaction temperature for melt polymerization is preferably within the range of (melting point - 30°C) to (melting point + 70)°C, and more preferably within the range of (melting point + 20)°C to (melting point + 50)°C.

[0043] The melt polymerization is preferably carried out in the presence of a catalyst and without a solvent (except for the above-mentioned acetic anhydride). 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.

[0044] 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 (melting point -70)°C to (melting point -10)°C. The reaction temperature of the solid-state polymerization may be changed stepwise, and the final temperature achieved by the solid-state polymerization is preferably (melting point -50)°C to (melting point -10)°C, and more preferably (melting point -40)°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.

[0045] 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.

[0046] (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.

[0047] (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.

[0048] 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.

[0049] (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.

[0050] 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.

[0051] (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.

[0052] 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.

[0053] (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.

[0054] 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.

[0055] 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.

[0056] (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.

[0057] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0058] <Production Examples of Liquid Crystal Polyester Resin> (Example 1-1) 24.9 mol % of p-hydroxybenzoic acid (HBA), 72.6 mol % of 6-hydroxy-2-naphthoic acid (HNA), 2.0 mol % of 6-hydroxynicotinic acid (HNIA), and 0.5 mol % of terephthalic acid (TPA) were placed in a polymerization vessel equipped with a stirring blade, potassium acetate was charged as a catalyst, the polymerization vessel was subjected to a cycle of reduced pressure and nitrogen injection three times, and then acetic anhydride (1.05 molar equivalents relative to the hydroxyl groups) was further added, the temperature was raised to 160°C, and an acetylation reaction was carried out under reflux for 1.5 hours.

[0059] After the acetylation was completed, 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 310°C. 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. The resulting polymer was then heated in an inert 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 under the following conditions: 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, then raised to 290°C and maintained for 2 hours, and finally raised to 300°C and maintained for 3.5 hours. The temperature change in each step was carried out as quickly as possible within the capabilities of the apparatus. The solid-state polymerization conditions shown in Table 1, "250-2h, 270-2h, 290-2h, 300-3.5h" indicate that solid-state polymerization was carried out at 250°C for 2 hours, at 270°C for 2 hours, at 290°C for 2 hours, and at 300°C for 3.5 hours.

[0060] 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 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.

[0061] (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 24.8 mol% HBA, 72.3 mol% HNA, 2.0 mol% HNIA, and 0.9 mol% TPA, 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, then raised to 270°C and maintained for 2 hours, then raised to 290°C and maintained for 3 hours, and then raised to 300°C and maintained for 3 hours. Next, the liquid crystallinity of the polyester resin was confirmed in the same manner as above.

[0062] (Example 1-3) A polyester resin was obtained in the same manner as in Example 1-1, except that the monomer charge was changed to 25.9 mol% HBA, 69.6 mol% HNA, 4.0 mol% HNIA, and 0.5 mol% isophthalic acid (IPA), 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, then raised to 270°C and maintained for 2 hours, and then raised to 290°C and maintained for 6 hours. Next, the liquid crystallinity of the polyester resin was confirmed in the same manner as above.

[0063] (Example 1-4) A polyester resin was obtained in the same manner as in Example 1-1, except that the monomer charge was changed to 25.9 mol% HBA, 69.6 mol% HNA, 4.0 mol% HNIA, and 0.5 mol% TPA, 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, then raised to 270°C and maintained for 2 hours, then raised to 290°C and maintained for 9 hours, and then raised to 300°C and maintained for 2 hours. Next, the liquid crystallinity of the polyester resin was confirmed in the same manner as above.

[0064] (Example 1-5) A polyester resin was obtained in the same manner as in Example 1-1, except that the monomer charge was changed to 24.9 mol% HBA, 68.6 mol% HNA, 6.0 mol% HNIA, and 0.5 mol% TPA, 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, then raised to 270°C and maintained for 2 hours, then raised to 280°C and maintained for 4 hours, and then raised to 290°C and maintained for 9 hours. Next, the liquid crystallinity of the polyester resin was confirmed in the same manner as above.

[0065] (Example 1-6) A polyester resin was obtained in the same manner as in Example 1-1, except that the monomer charge was changed to 18.9 mol% HBA, 72.6 mol% HNA, 8.0 mol% HNIA, and 0.5 mol% TPA, 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, then raised to 270°C and maintained for 2 hours, then raised to 290°C and maintained for 3 hours, and then raised to 300°C and maintained for 5.5 hours. Next, the liquid crystallinity of the polyester resin was confirmed in the same manner as above.

[0066] (Example 1-7) A polyester resin was obtained in the same manner as in Example 1-1, except that the monomer charge was changed to 22.9 mol% HBA, 68.6 mol% HNA, 8.0 mol% HNIA, and 0.5 mol% TPA, 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, then raised to 270°C and maintained for 2 hours, then raised to 280°C and maintained for 4 hours, and then raised to 290°C and maintained for 9 hours. Next, the liquid crystallinity of the polyester resin was confirmed in the same manner as above.

[0067] Comparative Example 1-1 A polyester resin was obtained in the same manner as in Example 1-1, except that the monomer charge was changed to 24.8 mol% HBA, 72.3 mol% HNA, 2.0 mol% HNIA, and 0.9 mol% 2,6-naphthalenedicarboxylic acid (NADA), 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, then raised to 270°C and maintained for 2 hours, then raised to 290°C and maintained for 3 hours, and then raised to 300°C and maintained for 3 hours. Next, the liquid crystallinity of the polyester resin was confirmed in the same manner as above.

[0068] Example 2-1 A polyester resin was obtained in the same manner as in Example 1-1, except that the monomer charge was changed to 28.9 mol% HBA, 68.6 mol% HNA, 2.0 mol% m-hydroxybenzoic acid (mHBA), and 0.5 mol% TPA, 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, then raised to 270°C and maintained for 2 hours, and then raised to 290°C and maintained for 3 hours. Next, the liquid crystallinity of the polyester resin was confirmed in the same manner as above.

[0069] (Example 2-2) The monomer charge was changed to 24.9 mol% HBA, 72.6 mol% HNA, 2.0 mol% mHBA, and 0.5 mol% TPA, magnesium acetate was charged in addition to potassium acetate as a catalyst, acetic anhydride (1.08 molar equivalents relative to the hydroxyl group) was added, and 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 250°C and maintained for 2 hours, and then raised to 270°C and maintained for 1 hour. Next, the liquid crystallinity of the polyester resin was confirmed in the same manner as above.

[0070] (Example 2-3) A polyester resin was obtained in the same manner as in Example 2-2, except that 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 270°C and maintained for 1.5 hours. Next, the liquid crystallinity of the polyester resin was confirmed in the same manner as above.

[0071] (Example 2-4) A polyester resin was obtained in the same manner as in Example 2-2, except that 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 270°C and maintained for 2 hours. Next, the liquid crystallinity of the polyester resin was confirmed in the same manner as above.

[0072] (Example 2-5) A polyester resin was obtained in the same manner as in Example 2-2, except that 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 270°C and maintained for 3 hours. Next, the liquid crystallinity of the polyester resin was confirmed in the same manner as above.

[0073] (Example 2-6) Monomers were charged in the same manner as in Example 2-2, except that only potassium acetate was used as the catalyst. After acetylation was completed, the polymerization vessel, which had been in a state where acetic acid was being distilled, was heated at a rate of 0.6°C / min until the melting zone temperature in the vessel reached 350°C, and then the pressure was reduced to 10 hPa over 30 minutes. When a predetermined torque was reached, the polymerization reaction was terminated, and the polymer was extracted and cooled to solidify. A polyester resin was obtained from the obtained polymer in the same manner as in Example 2-2, 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.

[0074] (Example 2-7) A polyester resin was obtained in the same manner as in Example 2-4, except that N-methylimidazole (770 ppm based on the total weight of HBA, HNA, and mHBA in the system) was used as the catalyst. In the solid-state polymerization, the temperature was raised from room temperature to 250°C and maintained for 2 hours, and then raised to 290°C and maintained for 1.5 hours. Next, the liquid crystallinity of the polyester resin was confirmed in the same manner as above.

[0075] (Example 2-8) A polyester resin was obtained in the same manner as in Example 2-2, except that the monomer charge was changed to 24.8 mol% HBA, 72.3 mol% HNA, 2.0 mol% mHBA, and 0.9 mol% TPA, 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 290°C and maintained for 1.5 hours. Next, the liquid crystallinity of the polyester resin was confirmed in the same manner as above.

[0076] Example 2-9 A polyester resin was obtained in the same manner as in Example 2-1, except that the monomer charge was changed to 24.9 mol% HBA, 72.6 mol% HNA, 2.0 mol% mHBA, and 0.5 mol% 4,4'-dihydroxybiphenyl (BP), 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, then raised to 270°C and maintained for 2 hours, and then raised to 290°C and maintained for 3 hours. Next, the liquid crystallinity of the polyester resin was confirmed in the same manner as above.

[0077] (Example 2-10) A polyester resin was obtained in the same manner as in Example 2-1, except that the monomer charge was changed to 19.9 mol% HBA, 74.6 mol% HNA, 5.0 mol% mHBA, and 0.5 mol% TPA, 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, then raised to 270°C and maintained for 2 hours, then raised to 290°C and maintained for 2 hours, and then raised to 300°C and maintained for 0.5 hours. Next, the liquid crystallinity of the polyester resin was confirmed in the same manner as above.

[0078] (Example 2-11) A polyester resin was obtained in the same manner as in Example 2-1, except that the monomer charge was changed to 22.9 mol% HBA, 71.6 mol% HNA, 5.0 mol% mHBA, and 0.5 mol% TPA, 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, then raised to 270°C and maintained for 2 hours, then raised to 290°C and maintained for 2 hours, and then raised to 300°C and maintained for 0.5 hours. Next, the liquid crystallinity of the polyester resin was confirmed in the same manner as above.

[0079] (Example 2-12) A polyester resin was obtained in the same manner as in Example 2-1, except that the monomer charge was changed to 24.9 mol% HBA, 68.6 mol% HNA, 6.0 mol% mHBA, and 0.5 mol% TPA, 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 270°C and maintained for 4 hours. Next, the liquid crystallinity of the polyester resin was confirmed in the same manner as above.

[0080] (Example 2-13) A polyester resin was obtained in the same manner as in Example 2-1, except that the monomer charge was changed to 16.9 mol% HBA, 74.6 mol% HNA, 8.0 mol% mHBA, and 0.5 mol% TPA, 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, then raised to 270°C and maintained for 2 hours, then raised to 290°C and maintained for 2 hours, and then raised to 300°C and maintained for 1 hour. Next, the liquid crystallinity of the polyester resin was confirmed in the same manner as above.

[0081] (Example 2-14) A polyester resin was obtained in the same manner as in Example 2-1, except that the monomer charge was changed to 11.9 mol% HBA, 79.6 mol% HNA, 8.0 mol% mHBA, and 0.5 mol% TPA, 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, then raised to 270°C and maintained for 2 hours, and then raised to 310°C and maintained for 2 hours. Next, the liquid crystallinity of the polyester resin was confirmed in the same manner as above.

[0082] (Example 2-15) A polyester resin was obtained in the same manner as in Example 2-2, except that the monomer charge was changed to 24.8 mol% HBA, 72.3 mol% HNA, 2.0 mol% mHBA, and 0.9 mol% BP, 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.

[0083] Comparative Example 2-1 A polyester resin was obtained in the same manner as in Example 2-1, except that the monomer charge was changed to 20.0 mol% HBA, 73.0 mol% HNA, and 7.0 mol% mHBA, 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 270°C and maintained for 1 hour. Next, the liquid crystallinity of the polyester resin was confirmed in the same manner as above.

[0084] Comparative Example 2-2 A polyester resin was obtained in the same manner as in Example 2-6, except that the amount of acetic anhydride added was changed to 1.05 molar equivalents relative to the hydroxyl groups and solid-state polymerization was not performed. Next, the liquid crystallinity of the polyester resin was confirmed in the same manner as above.

[0085] (Comparative Example 2-3) A polyester resin was obtained in the same manner as in Example 2-2, except that the monomer charge was changed to 25.0 mol% HBA, 73.0 mol% HNA, and 2.0 mol% mHBA, 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.

[0086] (Comparative Example 2-4) The monomer charge was changed to 24.8 mol% HBA, 72.3 mol% HNA, 2.0 mol% mHBA, and 0.9 mol% TPA, and a polyester resin was obtained in the same manner as in Comparative Example 2-2, except that solid-state polymerization was not performed. Next, the liquid crystallinity of the polyester resin was confirmed in the same manner as above.

[0087] (Comparative Example 2-5) The monomer charge was changed to 22.0 mol% HBA, 74.0 mol% HNA, 3.0 mol% mHBA, and 1.0 mol% TPA, and no catalyst was used. Acetic anhydride (1.03 molar equivalents relative to the hydroxyl groups) was charged. After acetylation was completed, the polymerization vessel was quickly heated to 210°C in an acetic acid distillation state and maintained at that temperature for 30 minutes. The temperature was then raised to 350°C over 4 hours, and the pressure was reduced to 10 hPa over 80 minutes. The load on the stirring motor stirring the reaction was monitored, and the polymerization reaction was terminated when a predetermined torque was reached. The polymer was extracted and cooled to solidify. A polyester resin was obtained in the same manner as in Example 2-1, except that solid-state polymerization was not performed. Next, the liquid crystallinity of the polyester resin was confirmed in the same manner as above.

[0088] (Comparative Example 2-6) A polyester resin was obtained in the same manner as in Comparative Example 2-5, except that solid-state polymerization was carried out under the following conditions. In the solid-state polymerization, the temperature was raised from room temperature to 280°C and maintained for 1 hour, raised to 285°C and maintained for 1 hour, and raised to 290°C and maintained for 1.25 hours. Next, the liquid crystallinity of the polyester resin was confirmed in the same manner as above.

[0089] (Comparative Example 2-7) Monomer charging was changed to 24.3 mol% HBA, 70.9 mol% HNA, 1.9 mol% mHBA, and 2.9 mol% TPA, and a polyester resin was obtained in the same manner as in Comparative Example 2-2, except that solid-state polymerization was not performed. Next, the liquid crystallinity of the polyester resin was confirmed in the same manner as above.

[0090] (Comparative Example 2-8) A polyester resin was obtained in the same manner as in Comparative Example 2-2, except that the monomer charge was changed to 23.8 mol% HBA, 69.5 mol% HNA, 1.9 mol% mHBA, and 4.8 mol% TPA, and solid-state polymerization was not performed. Next, the liquid crystallinity of the polyester resin was confirmed in the same manner as above.

[0091] (Comparative Example 2-9) A polyester resin was obtained in the same manner as in Example 2-2, except that the monomer charge was changed to 22.7 mol% HBA, 66.4 mol% HNA, 1.8 mol% mHBA, and 9.1 mol% TPA, 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 290°C and maintained for 3 hours. However, in this solid-state polymerization process, the polyester resin melted, and the degree of polymerization could not be increased appropriately.

[0092] Example 3-1 A polyester resin was obtained in the same manner as in Example 1-1, except that the monomer charge was changed to 20.7 mol% HBA, 77.1 mol% HNA, 1.7 mol% 4'-hydroxy-4-biphenylcarboxylic acid (HPBA), and 0.5 mol% TPA, 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, then raised to 270°C and maintained for 2 hours, then raised to 290°C and maintained for 3 hours, then raised to 300°C and maintained for 1 hour, and finally raised to 310°C and maintained for 1 hour. Next, the liquid crystallinity of the polyester resin was confirmed in the same manner as above.

[0093] (Example 3-2) The monomer charge was changed to 28.9 mol% HBA, 68.6 mol% HNA, 2.0 mol% HPBA, and 0.5 mol% TPA, and a polyester resin was obtained in the same manner as in Example 3-1, except that the solid-state polymerization conditions were changed as follows. In the solid-state polymerization, the temperature was raised from room temperature to 250 ° C. and held for 2 hours, then raised to 270 ° C. and held for 2 hours, then raised to 280 ° C. and held for 2 hours, then raised to 290 ° C. and held for 3 hours, and then raised to 300 ° C. and held for 1 hour. Next, the liquid crystallinity of the polyester resin was confirmed in the same manner as above.

[0094] (Comparative Example 4-1) A polyester resin was obtained in the same manner as in Example 1-1, except that the monomer charge was changed to 25.0 mol% HBA, 70.0 mol% HNA, 2.5 mol% TPA, and 2.5 mol% BP, 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 3 hours, and then raised to 280°C and maintained for 3 hours. Next, the liquid crystallinity of the polyester resin was confirmed in the same manner as above.

[0095] (Comparative Example 4-2) A polyester resin was obtained in the same manner as in Comparative Example 4-1, except that the monomer charge was changed to 23.8 mol% HBA, 75.5 mol% HNA, and 0.7 mol% TPA, 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, then raised to 270°C and maintained for 2 hours, then raised to 290°C and maintained for 3 hours, and then raised to 300°C and maintained for 1 hour. Next, the liquid crystallinity of the polyester resin was confirmed in the same manner as above.

[0096] (Comparative Example 4-3) A polyester resin was obtained in the same manner as in Example 2-2, except that the monomer charge was changed to 73.0 mol% HBA and 27.0 mol% HNA, 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 3 hours. Next, the liquid crystallinity of the polyester resin was confirmed in the same manner as above.

[0097] (Comparative Example 4-4) A polyester resin was obtained in the same manner as in Comparative Example 4-1, except that the monomer charge was changed to HBA 70.0 mol%, HNA 2.0 mol%, NADA 14.0 mol%, and HQ 14.0 mol%. Next, the liquid crystallinity of the polyester resin was confirmed in the same manner as above.

[0098] Example 5-1: 95.0 parts by mass of the polyester resin of Example 2-4 and 5.0 parts by mass of the polyester resin of Comparative Example 4-3 were kneaded using an extruder equipped with a twin-screw kneader (Labo Plastomill Micro, small extrusion segment 2D15W, manufactured by Toyo Seiki Seisakusho, Ltd.) under conditions of a heating temperature of 340°C and a screw rotation of 40 rpm, to obtain a polymer blend. Next, in the same manner as above, it was confirmed that the produced polyester resin was uniformly compatible and exhibited liquid crystallinity.

[0099] Example 5-2 A polymer blend was obtained in the same manner as in Example 5-1, except that 95.0 parts by mass of the polyester resin of Example 2-5 and 5.0 parts by mass of the polyester resin of Comparative Example 4-3 were used in the production of the polymer blend. Next, in the same manner as above, it was confirmed that the produced polyester resin was uniformly compatible and exhibited liquid crystallinity.

[0100] Example 5-3 A polymer blend was obtained in the same manner as in Example 5-1, except that 90.0 parts by mass of the polyester resin of Example 2-5 and 10.0 parts by mass of the polyester resin of Comparative Example 4-3 were used in the production of the polymer blend. Next, in the same manner as above, it was confirmed that the produced polyester resin was uniformly compatible and exhibited liquid crystallinity.

[0101] Example 5-4 A polymer blend was obtained in the same manner as in Example 5-1, except that 95.0 parts by mass of the polyester resin of Example 2-5 and 5.0 parts by mass of the polyester resin of Comparative Example 4-4 were used in the production of the polymer blend. Next, in the same manner as above, it was confirmed that the produced polyester resin was uniformly compatible and exhibited liquid crystallinity.

[0102] Tables 1 to 5 show the composition ratios (mol %) of the structural units of the polyester resins produced in the above Examples and Comparative Examples and the conditions of solid-state polymerization.

[0103] <Performance Evaluation 1 of Liquid Crystal Polyester Resin> <Measurement of Melting Point and Crystallization Point> The melting points and crystallization 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 completely melted by heating from room temperature to 360°C at a heating rate of 10°C / min, 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). 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 points (Tm) and crystallization points (Tc) are shown in Tables 6 to 10. In the tables, "-" indicates undetectable.

[0104] <Measurement of Melt Viscosity> The melt viscosity (Pa s) of the liquid crystal polyester resins obtained in the examples and comparative examples was measured at 350°C and a shear rate of 1000 / s 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 in accordance with JIS K7199. The measurement results are shown in Tables 6 to 10.

[0105] <Preparation of Flat Test Pieces> The liquid crystal polyester resins obtained in the examples and comparative examples were heated and melted at a temperature 20°C above their melting point, and then injection molded (mold temperature 80°C) to prepare flat test pieces measuring 30 mm x 30 mm x 0.4 mm (thickness).

[0106] <Measurement of Dielectric Constant and Dielectric Loss Tangent (10 GHz)> The dielectric loss tangent (tan δ) in the in-plane direction of the flat test specimen prepared above was measured at a frequency of 10 GHz using a Keysight Technologies N5247A network analyzer by the split post dielectric resonator method (SPDR method) under an environment of a temperature of 23°C and a humidity of 50% rh. The product of the dielectric constant measured under these measurement conditions and the dielectric loss tangent and the square root of the dielectric constant was also calculated. The measurement results and calculation results are shown in Tables 6 to 10. The lower the values ​​of the dielectric constant, dielectric loss tangent, and the product of the dielectric constant and the square root of the dielectric loss tangent, the more the influence of dielectric loss can be reduced.

[0107] As is clear from the results in Tables 6 to 10, the liquid crystal polyester resins of Examples 1-1 to 1-7, Examples 2-1 to 2-15, Examples 3-1 to 3-2, and Examples 5-1 to 5-4 exceeded a specific viscosity range under high temperature conditions, while having low values ​​of dielectric constant, dielectric loss tangent, and the product of the dielectric constant to the half power and the dielectric loss tangent. Note that the liquid crystal polyester resin of Comparative Example 2-9 was shown as "-" in Table 7 because the above items could not be measured.

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[0118] <Performance Evaluation 2 of Liquid Crystal Polyester Resin> <Preparation of Bending Test Piece> The liquid crystal polyester resins obtained in Examples 1-3, 2-4, 2-5, 2-7, 2-9, 3-2, 5-1, and 5-3 and Comparative Examples 2-5 and 4-1 were heated and melted at a melting point of +20°C, and injection molded (mold temperature of 80°C) to prepare bending test pieces of 80 mm x 12.5 mm x 2 mm (thickness).

[0119] <Measurement of Deflection Temperature Under Load (DTUL)> Using the bending test specimens prepared above, the deflection temperature under load (DTUL) was measured edgewise (applied to a 12.5 mm x 2 mm surface) at a load of 0.45 MPa according to ASTM D648. The average values ​​measured with N=3 are shown in Table 11. A higher deflection temperature under load indicates better practical heat resistance.

[0120]

[0121] <Performance Evaluation 3 of Liquid Crystal Polyester Resin> <Number of Foreign Matter Before and After Heat Treatment> The surface of the flat test pieces of Examples 2-4, 2-7, 2-14 and Comparative Examples 2-3, 2-7, and 2-8 prepared above was photographed at 30x magnification using a Keyence VHX-7000. Images were then taken of the surfaces of the flat test pieces. The number of black foreign matter particles measuring 30 μm or larger was counted before the heat treatment. Subsequently, the flat test pieces of Examples 2-4, 2-7, 2-14 and Comparative Examples 2-3, 2-7, and 2-8 prepared above were heated in an oven at a melting point of +10 to 20°C for 5 minutes in the atmosphere. The number of black foreign matter particles measuring 30 μm or larger after the heat treatment was counted using images photographed at 30x magnification using a Keyence VHX-7000. The measurement results are shown in Table 12. The smaller the increase in the number of foreign matter particles before and after the heat treatment, the more likely it is that the molded product will have poor appearance or poor physical properties.

[0122]

[0123] <Performance Evaluation 4 of Liquid Crystal Polyester Resin> <Amount of Outgassing> 3 g of each powder sample of the liquid crystal polyester resin of Examples 2-7, 2-14, and Comparative Example 2-3 obtained above was heated at 190°C for 1 hour in a headspace sampler (Agilent Technologies 7697A), and the compounds contained in the sample vaporized in the sample vaporization chamber. The vaporized components generated at this time were referred to as outgassing, and the sample was received in a gas chromatography unit (Agilent Technologies 7820A) heated to 45°C and allowed to stand for 3 minutes. The mobile phase called carrier gas flowing through the gas chromatography transports the vaporized components to be analyzed to the column. The temperature was then raised from room temperature to 280°C at a rate of 20°C / min, and the outgassing transported to the column was quantified and evaluated as the ratio of the outgas weight to the initial sample weight. The measurement results are shown in Table 13. The lower the amount of outgassing, the more likely it is that the molded product will have poor appearance and reduced physical properties.

[0124]

Claims

1. A liquid crystal polyester resin comprising 90 mol % or more of all structural units derived from a hydroxycarboxylic acid, wherein the structural units derived from the hydroxycarboxylic acid comprise a structural unit (A) derived from p-hydroxybenzoic acid, a structural unit (B) derived from 6-hydroxy-2-naphthoic acid, and a structural unit (C) derived from a hydroxycarboxylic acid other than the structural units (A) and (B), and the structural unit (C) is a structural unit derived from at least one selected from the group consisting of m-hydroxybenzoic acid, 6-hydroxynicotinic acid, and 4'-hydroxy-4-biphenylcarboxylic acid, the liquid crystal polyester resin further comprises at least one of a structural unit (D) derived from a dicarboxylic acid and a structural unit (E) derived from a diol, and the composition ratio (mol %) of the structural units (A) to (E) satisfies the following conditions: 10 mol %≦structural unit (A)≦30 mol %, 60 mol %≦structural unit (B)≦80 mol %, and 0.1 mol %≦structural unit (C)≦10 mol %. A liquid crystal polyester resin, which satisfies the condition: 0.1 mol %≦structural unit (D) + structural unit (E) ≦ 2.0 mol %, and which has a melt viscosity of 25 Pa·s or more measured at 350° C. and a shear rate of 1000 / s.

2. The dielectric tangent at a measurement frequency of 10 GHz is 1.0 x 10 －３ The liquid crystal polyester resin according to claim 1 , wherein the liquid crystal polyester resin has a viscosity of 100° C. or less.

3. The product of the dielectric constant to the square root and the dielectric loss tangent at a measurement frequency of 10 GHz is 1.70 x 10 －３ The liquid crystal polyester resin according to claim 1, wherein:

4. The liquid crystal polyester resin according to claim 1, wherein the composition ratio (mol %) of the structural unit (C) satisfies the following condition: 0.1 mol %≦structural unit (C)≦6.0 mol %.

5. The liquid crystal polyester resin according to claim 1, wherein the structural unit (C) is a structural unit derived from m-hydroxybenzoic acid.

6. The liquid crystal polyester resin according to claim 1, which is composed only of structural units derived from the hydroxycarboxylic acid and structural units (D) derived from a dicarboxylic acid.

7. The liquid crystal polyester resin according to claim 1, wherein the composition ratio (mol %) of the structural unit (D) satisfies the following condition: 0.1 mol %≦structural unit (D)<1.0 mol %.

8. The liquid crystal polyester resin according to claim 1, wherein the composition ratio (mol %) of the structural unit (D) satisfies the following condition: 0.1 mol %≦structural unit (D)<0.8 mol %.

9. The liquid crystal polyester resin according to claim 1, wherein the structural unit (D) is a structural unit derived from terephthalic acid.

10. The liquid crystal polyester resin according to claim 1, wherein the melting point of said liquid crystal polyester resin is 230° C. or higher.

11. The liquid crystal polyester resin according to claim 1, wherein the liquid crystal polyester resin has a deflection temperature under load of 220° C. or higher.

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

13. A sheet-like molded product comprising the liquid crystal polyester resin according to any one of claims 1 to 11.

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

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

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