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

Abstract

[Problem] To provide a liquid-crystal polyester resin having excellent dimensional stability while having a low dielectric loss tangent. [Solution] A liquid-crystal polyester resin according to the present invention contains constituent units derived from an aromatic hydroxycarboxylic acid in an amount of 90 mol% or larger with respect to all the constituent units, and is characterized by: further containing a constituent unit derived from an aromatic diol and / or a constituent unit derived from an aromatic diamine and containing a constituent unit derived from an aromatic dicarboxylic acid; having a dielectric loss tangent at a measurement frequency of 10 GHz of 1.0×10-3 or less; giving an injection-molded piece which has a difference (anisotropy) in molding shrinkage between the flow direction (MD) and a direction (TD) perpendicular to the flow direction of 1.00 or less; having a melting point of 280°C or higher; and having a melt viscosity, as measured under the conditions of temperatures ranging from the melting point to [melting point + 20°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 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 volume of information communication in the field of communication, the use of signals having frequencies in the high frequency band has increased in electronic devices and communication devices, and in particular, ９ Signals with frequencies in the gigahertz (GHz) band, which is 100 Hz or higher, are being widely used. For example, high frequencies in the GHz band 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, the quality of the output signal decreases, which can lead to erroneous recognition of information, i.e., transmission loss increases. This transmission loss consists of conductor loss due to the conductor and dielectric loss due to insulating resins that make up electrical and electronic components such as circuit boards in electronic devices and communication devices. Since conductor loss is proportional to the 0.5th power of the frequency used and dielectric loss is proportional to the first power of the frequency, the impact of this dielectric loss becomes very large in high frequency bands, especially in the GHz band. Furthermore, since dielectric loss increases in proportion to the dielectric loss tangent of the resin, resins with low dielectric loss tangents are required to prevent information degradation.

[0004] Furthermore, resins constituting electric and electronic components are also required to have heat resistance, moldability, etc. For example, Patent Document 1 proposes a wholly aromatic polyester resin that has excellent heat resistance and moldability, and that contains 40 to 75 mol % of structural units derived from 6-hydroxy-2-naphthoic acid, 8.5 to 30 mol % of structural units derived from terephthalic acid, 8.5 to 30 mol % of structural units derived from 4,4′-dihydroxybiphenyl, and 0.1 to 8 mol % of structural units derived from p-hydroxybenzoic acid in specific compositional ratios.

[0005] Japanese Patent Application Laid-Open No. 2002-179776

[0006] However, the present inventors have found that even if the wholly aromatic polyester resin proposed in Patent Document 1 is used, it is not possible to obtain a liquid crystal polyester resin that has a sufficiently low dielectric tangent and excellent dimensional stability.

[0007] Therefore, the present inventors conducted extensive research to solve the above problems, and found that, in a liquid crystal polyester resin containing structural units derived from aromatic hydroxycarboxylic acid in an amount of 90 mol% or more of all structural units, by adjusting specific properties (dielectric loss tangent, anisotropy, melt viscosity) and the composition ratio of specific structural units, a liquid crystal polyester resin having a low dielectric loss tangent and excellent dimensional stability can be obtained.

[0008] Therefore, an object of the present invention is to provide a liquid crystal polyester resin having a low dielectric tangent and excellent dimensional stability. Another object of the present invention is to provide a molded article containing the liquid crystal polyester resin and an electric / electronic component including the molded article.

[0009] That is, the present invention provides the following inventions: [1] A liquid crystal polyester resin containing 90 mol % or more of all structural units derived from aromatic hydroxycarboxylic acid, wherein the liquid crystal polyester resin further contains structural units derived from aromatic diol and / or structural units derived from aromatic diamine, and structural units derived from aromatic dicarboxylic acid, and has a dielectric loss tangent of 1.0 × 10 at a measurement frequency of 10 GHz. －３a difference (anisotropy) in molding shrinkage between the flow direction (MD) and the direction perpendicular to the flow direction (TD) of an injection-molded piece of the liquid crystal polyester resin is 1.00 or less; a melting point of the liquid crystal polyester resin is 280°C or higher; and a melt viscosity measured at a temperature between the melting point of the liquid crystal polyester resin and melting point + 20°C at a shear rate of 1000 / s is 25 Pa s or higher. [2] A liquid crystal polyester resin comprising 90 mol% or more of all structural units derived from an aromatic hydroxycarboxylic acid, wherein the aromatic hydroxycarboxylic acid comprises 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 hydroxycarboxylic acid other than the structural units (A) and (B), and the liquid crystal polyester resin further comprises structural units (D) derived from an aromatic diol and / or structural units (E) derived from an aromatic diamine, and structural units (F) derived from an aromatic dicarboxylic acid, wherein the composition ratios (mol%) of the structural units (A) to (E) satisfy the following conditions: 10 mol%≦structural unit (A)≦35 mol%, 50 mol%≦structural unit (B)≦85 mol%, 0.01 mol%≦structural unit (C)<15 mol%, and 0.01 mol%≦structural unit (D) + structural unit (E) + structural unit (F)≦5 mol%. [3] The liquid crystal polyester resin according to [2], wherein the structural unit (C) is derived from at least one structural unit selected from the group consisting of 4-(4-hydroxyphenyl)benzoic acid, 6-hydroxynicotinic acid, m-hydroxybenzoic acid, 4-hydroxy-3-methylbenzoic acid, 2-fluoro-4-hydroxybenzoic acid, 4-acetamidobenzoic acid, 4-(4-hydroxyphenoxy)benzoic acid, and coumaric acid. [4] The liquid crystal polyester resin according to [2], wherein the structural unit (C) is derived from at least one structural unit selected from the group consisting of 4-(4-hydroxyphenyl)benzoic acid, 6-hydroxynicotinic acid, and m-hydroxybenzoic acid. [5] The liquid crystal polyester resin according to any one of [1] to [4], wherein the melting point is 350°C or lower.[6] The liquid crystal polyester resin according to [5], wherein the temperature difference between the melting point and the crystallization point is 30°C or more. [7] A fibrous molded article comprising the liquid crystal polyester resin according to any one of [1] to [6]. [8] A sheet-like molded article comprising the liquid crystal polyester resin according to any one of [1] to [6]. [9] An injection-molded article comprising the liquid crystal polyester resin according to any one of [1] to [6].

[10] An electric / electronic component comprising the molded article according to [7].

[11] An electric / electronic component comprising the molded article according to [8].

[12] An electric / electronic component comprising the molded article according to [9].

[0010] According to the present invention, a liquid crystal polyester resin having a low dielectric loss tangent and excellent dimensional stability can be realized. By using the liquid crystal polyester resin of the present invention, the dimensional stability of the produced molded product can be improved. Therefore, when processed and molded and 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. Modes for carrying out the invention

[0011] (Liquid Crystal Polyester Resin) The liquid crystal polyester resin according to the present invention contains 90 mol% or more of structural units derived from aromatic hydroxycarboxylic acid based on all structural units, and further contains structural units derived from aromatic diol and / or structural units derived from aromatic diamine, and structural units derived from aromatic dicarboxylic acid. The liquid crystal polyester resin according to the present invention may be a single substance or a mixture (polymer blend). In the present invention, by satisfying the configuration of the following first embodiment and / or second embodiment, a liquid crystal polyester resin having a low dielectric tangent and excellent dimensional stability can be obtained.

[0012] First Embodiment In a first embodiment of the present invention, the liquid crystal polyester resin is characterized by having the following specific properties (dielectric loss tangent, anisotropy, melting point, and melt viscosity).

[0013] 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 1.0 × 10 －３ is preferably 0.90×10 or less.－３ is preferably 0.80×10 or less. －３ is preferably 0.75×10 or less. －３ By setting the dielectric dissipation factor of the liquid crystal polyester resin according to the present invention within the above-mentioned range, a molded article having a low dielectric dissipation factor 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 dissipation factor at 10 GHz of the liquid crystal polyester resin can be measured by the split post dielectric resonator method (SPDR method) using a network analyzer N5247A from Keysight Technologies, Inc., or the like, under an environment of a temperature of 23°C and a humidity of 50% RH.

[0014] The upper limit of the absolute value of the difference in mold shrinkage between the flow direction (MD) and the direction perpendicular to the flow direction (TD) of an injection-molded piece of the liquid crystal polyester resin according to the present invention (anisotropy) is 1.00 or less, preferably 0.95 or less, more preferably 0.90 or less, and even more preferably 0.85 or less. By setting the anisotropy of the liquid crystal polyester resin according to the present invention within the above numerical range, the dimensional stability of molded articles produced using the liquid crystal polyester resin can be improved. In this specification, the anisotropy of the liquid crystal polyester resin is the difference in mold shrinkage (TD mold shrinkage - MD mold shrinkage) calculated from the measurement results of the mold shrinkage (%) in MD and TD of a 50 mm x 50 mm x 1 mm flat test piece obtained by heating and melting the liquid crystal polyester resin at a temperature between the melting point and the melting point + 20°C.

[0015] The lower limit of the melting point of the liquid crystal polyester resin according to the present invention, in consideration of heat resistance, is 280° C. or higher, preferably 285° C. or higher, more preferably 290° C. or higher, even more preferably 295° 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 may be 350° C. or lower, 340° C. or lower, 330° C. or lower, 325° C. or lower, or 320° C. or lower. By setting the melting point of the liquid crystal polyester resin according to the present invention within the above numerical range, the heat resistance of molded articles produced using the liquid crystal polyester resin to heat processing can be improved.

[0016] The lower limit of the melt viscosity of the liquid crystal polyester resin according to the present invention, measured at a shear rate of 1000 / s at a temperature between the melting point and the melting point + 20°C, 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 50 Pa·s or more. The upper limit is preferably 1000 Pa·s or less, more preferably 500 Pa·s or less, even more preferably 200 Pa·s or less, and even more preferably 150 Pa·s or less. By controlling the melt viscosity of the liquid crystal polyester resin according to the present invention within the above numerical range, the dielectric dissipation factor can be further reduced, and the mechanical strength of the molded article can be improved. In this specification, the viscosity of the liquid crystal polyester resin can be measured using a capillary rheometer viscometer in accordance with JIS K7199.

[0017] Second Embodiment In a second embodiment of the present invention, the liquid crystal polyester resin contains, as aromatic hydroxycarboxylic acids, 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 further contains a structural unit (D) derived from an aromatic diol and / or a structural unit (E) derived from an aromatic diamine, and a structural unit (F) derived from an aromatic dicarboxylic acid. The composition ratios (mol %) of the structural units (A) to (F) satisfy the following conditions: 10 mol %≦structural unit (A)≦35 mol %, 50 mol %≦structural unit (B)≦85 mol %, 0.01 mol %≦structural unit (C)<15 mol %, and 0.01 mol %≦structural unit (D) + structural unit (E) + structural unit (F)≦5 mol %.

[0018] In the liquid crystal polyester resin according to the present invention, the composition ratios (mol %) of the structural units (A) to (F) preferably satisfy the following conditions: 15 mol %≦structural unit (A)≦33 mol %, 55 mol %≦structural unit (B)≦83 mol %, 0.05 mol %≦structural unit (C)≦12 mol %, 0.03 mol %≦structural unit (D)+structural unit (E)+structural unit (F)≦4 mol %, and more preferably satisfy the following conditions: 18 mol %≦structural unit (A)≦30 mol %, 57 mol %≦structural unit (B)≦80 mol %, 0.1 mol %≦structural unit (C)≦10 mol %, 0.05 mol %≦structural unit (D)+structural unit (E)+structural unit (F)≦3 mol %, and 19 mol %≦structural unit (A)≦29 mol %, 60 mol %≦structural unit (B)≦78 mol %, 0.5 mol %≦structural unit (C)≦8 mol %. It is more preferable that the following relationships are satisfied: 0.1 mol %≦structural unit (D)+structural unit (E)+structural unit (F)≦2.5 mol %, and it is particularly preferable that the following relationships are satisfied: 20 mol %≦structural unit (A)≦28 mol %, 63 mol %≦structural unit (B)≦75 mol %, 1 mol %≦structural unit (C)≦5 mol %, and 0.2 mol %≦structural unit (D)+structural unit (E)+structural unit (F)≦2 mol %.

[0019] The liquid crystal polyester resin of the second embodiment preferably has the specific properties (dielectric loss tangent, anisotropy, melting point, melt viscosity) described in the first embodiment. Furthermore, the liquid crystal polyester resin of the first and second embodiments preferably has the following specific property (temperature difference between the melting point and the crystallization point).

[0020] The lower limit of the crystallization point of the liquid crystal polyester resin according to the present invention is preferably 220°C or higher, more preferably 225°C or higher, even more preferably 230°C or higher, still more preferably 240°C or higher, and the upper limit is preferably 300°C or lower, more preferably 295°C or lower, even more preferably 290°C or lower, and still more preferably 280°C or lower. The lower limit of the temperature difference between the melting point and the crystallization point of the liquid crystal polyester resin according to the present invention (= "melting point (°C)" - "crystallization point (°C)") is preferably 30°C or higher, more preferably 35°C or higher, even more preferably 40°C or higher, and the upper limit is preferably 80°C or lower, more preferably 75°C or lower, and even more preferably 70°C or lower. By setting the temperature difference between the melting point and the crystallization point of the liquid crystal polyester resin according to the present invention within the above numerical range, when the liquid crystal polyester is melt-molded, it is possible to take a sufficient amount of time from when the liquid crystal polyester melts to when it solidifies, and it is possible to increase the degree of freedom in setting temperature conditions such as the molding temperature. In this specification, the melting point and crystallization point of the liquid crystal polyester resin are values ​​measured by a differential scanning calorimeter (DSC). Specifically, the liquid crystal polyester resin is heated from room temperature to 340 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 is then lowered to 30°C at a rate of 10°C / min is defined as the crystallization point (Tc), and the apex of the endothermic peak obtained when the temperature is further increased to 360°C at a rate of 10°C / min is defined as the melting point (Tm).

[0021] The liquid crystallinity of the liquid crystal polyester resin according to the present invention can be confirmed by using a polarizing microscope (product name: BH-2) manufactured by Olympus Corporation equipped with a hot stage for a microscope (product name: FP82HT) manufactured by Mettler, and then heating and melting the liquid crystal polyester resin on a heating stage of the microscope, and then observing whether or not it has optical anisotropy.

[0022] Hereinafter, each of the structural units contained in the liquid crystal polyester resin according to the present invention will be described in detail.

[0023] (Structural Unit (A) Derived from Aromatic Hydroxycarboxylic Acid) The structural unit (A) derived from aromatic 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.

[0024] The composition ratio (mol%) of the structural unit (A) in the liquid crystal polyester resin is preferably 10 mol% or more and 35 mol% or less.From the viewpoint of reducing the dielectric loss tangent of the liquid crystal polyester resin and improving the dimensional stability, the lower limit of the composition ratio (mol%) of the structural unit (A) is preferably 15 mol% or more, more preferably 18 mol% or more, even more preferably 19 mol% or more, still more preferably 20 mol% or more, and the upper limit is preferably 33 mol% or less, more preferably 30 mol% or less, still more preferably 29 mol% or less, still more preferably 28 mol% or less.

[0025] (Structural Unit (B) Derived from Aromatic Hydroxycarboxylic Acid) The structural unit (B) derived from aromatic 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.

[0026] The composition ratio (mol%) of the structural unit (B) in the liquid crystal polyester resin is preferably 50 mol% or more and 85 mol% or less.From the viewpoint of reducing the dielectric loss tangent of the liquid crystal polyester resin and improving the dimensional stability, the lower limit of the composition ratio (mol%) of the structural unit (B) is preferably 55 mol% or more, more preferably 57 mol% or more, even more preferably 60 mol% or more, still more preferably 63 mol% or more, and the upper limit is preferably 83 mol% or less, more preferably 80 mol% or less, still more preferably 78 mol% or less, still more preferably 75 mol% or less.

[0027] (Structural Unit (C) Derived from Aromatic Hydroxycarboxylic Acid) The structural unit (C) derived from an aromatic hydroxycarboxylic acid is not particularly limited, as long as it is a structural unit derived from a hydroxycarboxylic acid other than the structural units (A) and (B). The structural unit (C) is preferably, for example, a structural unit derived from at least one selected from the group consisting of 4-(4-hydroxyphenyl)benzoic acid, 6-hydroxynicotinic acid, m-hydroxybenzoic acid, 4-hydroxy-3-methylbenzoic acid, 2-fluoro-4-hydroxybenzoic acid, 4-(4-hydroxyphenoxy)benzoic acid, and coumaric acid. Of these, 4-(4-hydroxyphenyl)benzoic acid, 6-hydroxynicotinic acid, and m-hydroxybenzoic acid are more preferred. Examples of monomers that provide the structural unit (C) include these monomers, as well as acetylated products, ester derivatives, and acid halides thereof.

[0028] The composition ratio (mol%) of the structural unit (C) in the liquid crystal polyester resin is preferably 0.01 mol% or more and less than 15 mol%.From the viewpoint of reducing the dielectric loss tangent of the liquid crystal polyester resin and improving the dimensional stability, the lower limit of the composition ratio (mol%) of the structural unit (C) is preferably 0.05 mol% or more, more preferably 0.1 mol% or more, even more preferably 0.5 mol% or more, still more preferably 1 mol% or more, and the upper limit is preferably 12 mol% or less, more preferably 10 mol% or less, still more preferably 8 mol% or less, still more preferably 5 mol% or less.

[0029] (Structural Unit (D) Derived from Aromatic Diol) The structural unit (D) derived from an aromatic diol is preferably a structural unit derived from an aromatic diol represented by the following formula (1): Only one type of structural unit (D) may be contained, or two or more types of structural unit (D) may be contained.

[0030] In the above formula, Ar １ is a divalent hydrocarbon group having an aromatic ring, which may have a substituent as desired. 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.

[0031] Examples of monomers that provide the structural unit (D) include 4,4-dihydroxybiphenyl (BP), hydroquinone (HQ), methylhydroquinone (MeHQ), 4,4'-isopropylidenediphenol (BisPA), and acylated products, ester derivatives, and acid halides thereof.

[0032] (Structural Unit (E) Derived from Aromatic Diamine) The structural unit (E) derived from an aromatic diamine is preferably a structural unit derived from an aromatic diamine 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.

[0033] In the above formula, Ar ２is a divalent hydrocarbon group having an aromatic ring, which may have a substituent as desired. 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.

[0034] Examples of monomers that provide the structural unit (E) include p-diaminobenzene, 4,4'-diaminobiphenyl, naphthalenediamine, and acylated products, ester derivatives, and acid halides thereof.

[0035] (Structural Unit (F) Derived from Aromatic Dicarboxylic Acid) The structural unit (F) derived from an aromatic dicarboxylic acid is preferably a structural unit derived from an aromatic dicarboxylic acid represented by the following formula (3): Note that only one type of structural unit (F) may be included, or two or more types may be included.

[0036] In the above formula, Ar ３ is a divalent hydrocarbon group having an aromatic ring, which may have a substituent as desired. 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 (F) include terephthalic acid (TPA), isophthalic acid (IPA), 2,6-naphthalenedicarboxylic acid (NADA), and acylated products, ester derivatives, and acid halides thereof.

[0038] The total composition ratio (mol%) of the structural unit (D), the structural unit (E) and the structural unit (F) in the liquid crystal polyester resin is preferably 0.01 mol% or more and 5 mol% or less.From the viewpoint of reducing the dielectric loss tangent of the liquid crystal polyester resin and improving the dimensional stability, the lower limit of the total composition ratio (mol%) of the structural unit (D), the structural unit (E) and the structural unit (F) is preferably 0.03 mol% or more, more preferably 0.05 mol% or more, even more preferably 0.1 mol% or more, still more preferably 0.2 mol% or more, and the upper limit is preferably 4 mol% or less, more preferably 3 mol% or less, even more preferably 2.5 mol% or less, still more preferably 2 mol% or less.

[0039] (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), at least one of the monomers that provide the structural unit (D) and the monomer that provides the structural unit (E), and a monomer that provides the structural unit (F) to obtain a polymer, and solid-state polymerizing the polymer to obtain a liquid crystal polyester resin.

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

[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 for solid-state polymerization is preferably the melting point or lower, and is preferably (melting point - 30) ° C to (melting point - 10) ° C. 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 fillers 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] <Production of Liquid Crystal Polyester Resin> (Example 1) 24 mol % of p-hydroxybenzoic acid (HBA), 73 mol % of 6-hydroxy-2-naphthoic acid (HNA), 2 mol % of m-hydroxybenzoic acid (mHBA), 0.5 mol % of 4,4′-dihydroxybiphenyl (BP), and 0.5 mol % of terephthalic acid (TPA) were placed in a polymerization vessel equipped with a stirring blade, and potassium acetate was charged as a catalyst. The polymerization vessel was subjected to a cycle of reduced pressure and nitrogen injection three times, after which acetic anhydride (1.05 molar equivalents relative to the hydroxyl groups) was further added, the temperature was raised to 150° C., and an acetylation reaction was carried out under reflux for 2 hours.

[0058] After the acetylation was completed, the polymerization vessel in the acetic acid distillation state was heated at a rate of 0.5°C / min until the melting zone temperature in the vessel reached 310°C. The polymer was then extracted and cooled to solidify. The obtained polymer was pulverized to a size that could pass through a sieve with a mesh size of 2.0 mm, thereby obtaining a polymer. The obtained polymer was then heated from room temperature to 300°C using an oven heater manufactured by Yamato Scientific Co., Ltd., and maintained at this temperature for 2 hours to carry out solid-state polymerization.

[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 a polarizing microscope (product name: BH-2) manufactured by Olympus Corporation equipped with a hot stage for a microscope (product name: FP82HT) manufactured by Mettler, and liquid crystallinity was confirmed based on the presence or absence of optical anisotropy.

[0060] Example 2 A polyester resin was obtained in the same manner as in Example 1, except that the monomer charges were changed to 24 mol% HBA, 72 mol% HNA, 2 mol% mHBA, 1 mol% BP, and 1 mol% TPA. Next, the liquid crystallinity of the polyester resin was confirmed in the same manner as above.

[0061] Example 3 A polyester resin was obtained in the same manner as in Example 1, except that the monomer charge was changed to 24 mol% HBA, 73 mol% HNA, 2 mol% mHBA, 0.5 mol% hydroquinone (HQ), and 0.5 mol% 2,6-naphthalenedicarboxylic acid (NADA). Next, the liquid crystallinity of the polyester resin was confirmed in the same manner as above.

[0062] Example 4 A polyester resin was obtained in the same manner as in Example 1, except that the monomer charge was changed to 22 mol% HBA, 73 mol% HNA, 2 mol% mHBA, 2 mol% 6-hydroxynicotinic acid (HNIA), 0.5 mol% BP, and 0.5 mol% TPA. Next, the liquid crystallinity of the polyester resin was confirmed in the same manner as above.

[0063] Example 5 A polyester resin was obtained in the same manner as in Example 1, except that the monomer charge was changed to 34 mol% HBA, 64.8 mol% HNA, 1 mol% mHBA, 0.1 mol% BP, and 0.1 mol% TPA. Next, the liquid crystallinity of the polyester resin was confirmed in the same manner as above.

[0064] Comparative Example 1 A polyester resin was obtained in the same manner as in Example 1, except that the monomer charges were changed to 73 mol % of HBA and 27 mol % of HNA. Next, the liquid crystallinity of the polyester resin was confirmed in the same manner as above.

[0065] Comparative Example 2 A polyester resin was obtained in the same manner as in Example 1, except that the monomer charge was changed to 60 mol% HBA, 20 mol% BP, 15 mol% TPA, and 5 mol% isophthalic acid (IPA). Next, the liquid crystallinity of the polyester resin was confirmed in the same manner as above.

[0066] Comparative Example 3 A polyester resin was obtained in the same manner as in Example 1, except that the monomer charge was changed to 6 mol% HBA, 40 mol% HNA, 27 mol% BP, and 27 mol% NADA. Next, the liquid crystallinity of the polyester resin was confirmed in the same manner as above.

[0067] Comparative Example 4 A polyester resin was obtained in the same manner as in Example 1, except that the monomer charges were changed to 35 mol% HBA, 50 mol% HNA, and 15 mol% 4-acetamidobenzoic acid (ABA). Next, the liquid crystallinity of the polyester resin was confirmed in the same manner as above.

[0068] Comparative Example 5 A polyester resin was obtained in the same manner as in Example 1, except that the monomer charges were changed to 19 mol% HBA, 79 mol% HNA, and 2 mol% mHBA. Next, the liquid crystallinity of the polyester resin was confirmed in the same manner as above.

[0069] Comparative Example 6 A polyester resin was obtained in the same manner as in Example 1, except that the monomer charges were changed to 23.8 mol% HBA, 75.5 mol% HNA, and 0.7 mol% IPA. Next, the liquid crystallinity of the polyester resin was confirmed in the same manner as above.

[0070] Comparative Example 7 A polyester resin was obtained in the same manner as in Example 1, except that the monomer charging was changed to 14.9 mol% HBA, 84.4 mol% HNA, and 0.7 mol% IPA. Next, the liquid crystallinity of the polyester resin was confirmed in the same manner as above.

[0071] Comparative Example 8 A polyester resin was obtained in the same manner as in Example 1, except that the monomer charges were changed to 23.8 mol% HBA, 75.5 mol% HNA, and 0.7 mol% TPA. Next, the liquid crystallinity of the polyester resin was confirmed in the same manner as above.

[0072] Comparative Example 9 A polyester resin was obtained in the same manner as in Example 1, except that the monomer charges were changed to 18 mol% HBA, 81 mol% HNA, and 1 mol% BP. Next, the liquid crystallinity of the polyester resin was confirmed in the same manner as above.

[0073] Comparative Example 10 A polyester resin was obtained in the same manner as in Example 1, except that the monomer charges were changed to 21 mol% HBA, 78 mol% HNA, 0.5 mol% BP, and 0.5 mol% TPA. Next, the liquid crystallinity of the polyester resin was confirmed in the same manner as above.

[0074] Comparative Example 11 A polyester resin was obtained in the same manner as in Example 1, except that the monomer charges were changed to 21 mol% HBA, 77 mol% HNA, and 2 mol% mHBA. Next, the liquid crystallinity of the polyester resin was confirmed in the same manner as above.

[0075] Comparative Example 12 A polyester resin was obtained in the same manner as in Example 1, except that the monomer charge was changed to 21 mol% HBA, 78 mol% HNA, 0.5 mol% HQ, and 0.5 mol% NADA. Next, the liquid crystallinity of the polyester resin was confirmed in the same manner as above.

[0076] Comparative Example 13 A polyester resin was obtained in the same manner as in Example 1, except that the monomer charges were changed to 21 mol% HBA, 68 mol% HNA, 3 mol% mHBA, 4 mol% BP, and 4 mol% IPA. Next, the liquid crystallinity of the polyester resin was confirmed in the same manner as above.

[0077] Table 1 shows the composition ratios (mol %) of the structural units of the polyester resins produced in the above Examples and Comparative Examples.

[0078] <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, the liquid crystal polyester resin was completely melted by heating from room temperature to 340-380°C at a heating 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 380°C at a rate of 10°C / min was taken as the melting point (Tm). The difference between the melting point and the crystallization point was calculated from the obtained melting point and crystallization point. The melting point (Tm), the crystallization point (Tc), and the difference between the melting point and the crystallization point (Tm-Tc) are shown in Table 1. In Table 1, "-" indicates not measured.

[0079] <Preparation of Flat Test Piece A> The liquid crystal polyester resins obtained in the examples and comparative examples were heated and melted at a temperature of from the melting point to the melting point + 20° C., and injection molded to prepare flat test pieces A measuring 30 mm×30 mm×0.4 mm.

[0080] <Preparation of Flat Test Piece B> The liquid crystal polyester resins obtained in the examples and comparative examples were heated and melted at a temperature of from the melting point to the melting point + 20° C., and injection molded to prepare flat test pieces B of 50 mm×50 mm×1 mm.

[0081] <Measurement of Dielectric Loss Tangent (10 GHz)> The dielectric loss tangent (tan δ) in the in-plane direction of the flat test piece A prepared above was measured at a frequency of 10 GHz using a network analyzer N5247A from Keysight Technologies Inc. in an environment of a temperature of 23°C and a humidity of 50% RH by the split post dielectric resonator method (SPDR method). The measurement results are shown in Table 1. In Table 1, "-" indicates that the measurement was not performed.

[0082] <Measurement of Anisotropy> The mold shrinkage (%) of the flat test piece B prepared above was measured in the flow direction (MD) and the direction perpendicular to the flow direction (TD), and the difference between these mold shrinkages (TD mold shrinkage - MD mold shrinkage) was calculated to evaluate the anisotropy. The calculation results are shown in Table 1. The smaller the difference, the smaller the anisotropy. In Table 1, "-" indicates that the measurement was not performed.

[0083] <Measurement of Melt Viscosity> The melt viscosity (Pa s) of the liquid crystal polyester resins obtained in Examples and Comparative Examples was measured at a melting point of +20°C and a shear rate of 1000 / s using a capillary rheometer viscometer (Capillograph 1D, manufactured by Toyo Seiki Seisakusho, Ltd.) and a capillary with an inner diameter of 1 mm in accordance with JIS K7199. The measurement results are shown in Table 1.

[0084] As is clear from the results in Table 1, the liquid crystal polyester resins of Examples 1 to 5 had a low dielectric loss tangent, a high melting point, excellent heat resistance, and small anisotropy, which provided excellent dimensional stability.

[0085]

Claims

1. A liquid crystal polyester resin containing 90 mol % or more of all structural units derived from aromatic hydroxycarboxylic acid, the liquid crystal polyester resin further containing structural units derived from aromatic diol and / or structural units derived from aromatic diamine, and structural units derived from aromatic dicarboxylic acid, and having a dielectric loss tangent of 1.0 x 10 at a measurement frequency of 10 GHz. －３ a difference (anisotropy) in molding shrinkage rates between a flow direction (MD) and a direction perpendicular to the flow direction (TD) of an injection-molded piece of the liquid crystal polyester resin is 1.00 or less; the melting point of the liquid crystal polyester resin is 280°C or more; and the melt viscosity measured at a temperature between the melting point of the liquid crystal polyester resin and melting point + 20°C at a shear rate of 1000 / s is 25 Pa·s or more.

2. A liquid crystal polyester resin comprising 90 mol% or more of all structural units derived from an aromatic hydroxycarboxylic acid, wherein the aromatic hydroxycarboxylic acid comprises 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 hydroxycarboxylic acid other than the structural units (A) and (B), wherein the liquid crystal polyester resin further comprises structural units (D) derived from an aromatic diol and / or structural units (E) derived from an aromatic diamine, and structural units (F) derived from an aromatic dicarboxylic acid, wherein the composition ratios (mol%) of the structural units (A) to (F) satisfy the following conditions: 10 mol%≦structural unit (A)≦35 mol%, 50 mol%≦structural unit (B)≦85 mol%, 0.01 mol%≦structural unit (C)<15 mol%, and 0.01 mol%≦structural unit (D) + structural unit (E) + structural unit (F)≦5 mol%.

3. The liquid crystal polyester resin according to claim 2, wherein the structural unit (C) is a structural unit derived from at least one selected from the group consisting of 4-(4-hydroxyphenyl)benzoic acid, 6-hydroxynicotinic acid, m-hydroxybenzoic acid, 4-hydroxy-3-methylbenzoic acid, 2-fluoro-4-hydroxybenzoic acid, 4-(4-hydroxyphenoxy)benzoic acid, and coumaric acid.

4. The liquid crystal polyester resin according to claim 2, wherein the structural unit (C) is a structural unit derived from at least one selected from the group consisting of 4-(4-hydroxyphenyl)benzoic acid, 6-hydroxynicotinic acid, and m-hydroxybenzoic acid.

5. The liquid crystal polyester resin according to any one of claims 1 to 4, which has a melting point of 350°C or less.

6. The liquid crystal polyester resin according to claim 5, wherein the temperature difference between the melting point and the crystallization point is 30° C. or more.

7. A fibrous molded article comprising the liquid crystal polyester resin according to any one of claims 1 to 4.

8. A sheet-like molded product comprising the liquid crystal polyester resin according to any one of claims 1 to 4.

9. An injection molded article comprising the liquid crystal polyester resin according to any one of claims 1 to 4.

10. An electric / electronic component comprising the molded article according to claim 7.

11. An electric / electronic component comprising the molded article according to claim 8.

12. An electric / electronic component comprising the molded article according to claim 9.

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