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

Abstract

To provide a liquid crystal polyester resin which is excellent in dimensional stability while having low dielectric loss tangent.SOLUTION: A liquid crystal polyester resin of the invention contains a constitutional unit derived from an aromatic hydroxy carboxylic acid in an amount of 90 mol% or more of the total constitutional units. The liquid crystal polyester resin further contains at least one constitutional unit selected from a constitutional unit derived from an aromatic monool, that derived from an aromatic monoamine, and that derived from an aromatic monocarboxylic acid. A dielectric loss tangent of the liquid crystal polyester resin at a measured frequency of 10 GHz is 1.0×10-3 or less. A difference (an anisotropy) between the mold shrinkage factor of the injection molded piece of the liquid crystal polyester resin in the flow direction (MD) and in the direction vertical to the flow direction (TD) is 1.00 or less. The melting point of the liquid crystal polyester resin is 280°C or more. The melt viscosity of the liquid crystal polyester resin between the melting point and the melting point+20°C measured at a shear rate of 1,000 / s is 25 Pa s or more.SELECTED DRAWING: None

Description

Technical Field

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

Background Art

[0002] In recent years, with the increase in information traffic in the communication field, the use of signals having frequencies in the high frequency band has increased in electronic devices, communication devices, etc. In particular, the frequency is 10 9 Hz or higher, and signals having frequencies in the gigahertz (GHz) band are being actively used. For example, the high frequency band of GHz is used in the automotive field. Specifically, in millimeter wave radars and quasi-millimeter wave radars mounted for the purpose of preventing collisions in automobiles, high frequencies of 76 to 79 GHz and 24 GHz are used respectively, and further spread is expected in the future.

[0003] However, as the frequency of the signal used increases, the quality of the output signal, which may cause misrecognition of information, deteriorates, that is, the transmission loss increases. This transmission loss consists of conductor loss due to the conductor and dielectric loss due to the resin for insulation that constitutes electric and electronic components such as substrates in electronic devices and communication devices. Since the conductor loss is proportional to the 0.5 power of the frequency used and the dielectric loss is proportional to the first power of the frequency, the influence of this dielectric loss becomes very large in the high frequency band, particularly in the GHz band. Further, since the dielectric loss increases in proportion to the dielectric tangent of the resin, a resin having a low dielectric tangent is required to prevent deterioration of information.

[0004] In addition, the resin constituting the electric and electronic components is also required to have heat resistance, moldability, etc. For example, Patent Document 1 proposes an all-aromatic polyester resin excellent in heat resistance and moldability, which contains structural units derived from 6-hydroxy-2-naphthoic acid in an amount of 40 to 75 mol%, structural units derived from terephthalic acid in an amount of 8.5 to 30 mol%, structural units derived from 4,4'-dihydroxybiphenyl in an amount of 8.5 to 30 mol%, and structural units derived from p-hydroxybenzoic acid in an amount of 0.1 to 8 mol% at a specific composition ratio.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, the inventors have found that even when using the all-aromatic polyester resin proposed in Patent Document 1, a liquid crystal polyester resin having sufficient low dielectric tangent and excellent dimensional stability cannot be obtained.

[0007] Therefore, as a result of intensive studies to solve the above problems, the inventors have found that in a liquid crystal polyester resin containing 90 mol% or more of structural units derived from aromatic hydroxycarboxylic acid in all structural units, by adjusting specific properties (dielectric tangent, anisotropy, melt viscosity) and the composition ratio of specific structural units, a liquid crystal polyester resin having a low dielectric 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 this liquid crystal polyester resin and an electric and electronic component including the molded article.

Means for Solving the Problems

[0009] That is, according to the present invention, the following inventions are provided. [1] A liquid crystal polyester resin comprising 90 mol% or more of structural units derived from an aromatic hydroxycarboxylic acid in all the structural units, wherein the liquid crystal polyester resin further contains at least one selected from structural units derived from an aromatic monool, structural units derived from an aromatic monoamine, and structural units derived from an aromatic monocarboxylic acid, the dielectric loss tangent at a measurement frequency of 10 GHz is 1.0×10 -3 or less, the difference (anisotropy) in the molding shrinkage rate 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, the melting point of the liquid crystal polyester resin is 280°C or higher, and the melt viscosity measured at a shear rate of 1000 / s at a temperature from the melting point of the liquid crystal polyester resin to the melting point + 20°C is 25 Pa·s or higher. The liquid crystal polyester resin is characterized by the above. [2] A liquid crystal polyester resin comprising 90 mol% or more of structural units derived from an aromatic hydroxycarboxylic acid in all the structural units, wherein the aromatic hydroxycarboxylic acid contains 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), the liquid crystal polyester resin further contains at least one selected from structural units (D) derived from an aromatic monool, structural units (E) derived from an aromatic monoamine, and structural units (F) derived from an aromatic monocarboxylic acid, and the composition ratio (mol%) of the structural units (A) to (E) satisfies 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% 0.01 mol% ≤ constitutional unit (D) + constitutional unit (E) + constitutional unit (F) ≤ 5 mol% A liquid crystal polyester resin, characterized by satisfying the above condition. [3] The liquid crystal polyester resin according to [2], wherein the constitutional unit (C) is a constitutional 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-acetamidobenzoic acid, 4-(4-hydroxyphenoxy)benzoic acid, and coumaric acid. [4] The liquid crystal polyester resin according to [2], wherein the constitutional unit (C) is a constitutional 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 [2] to [4], further comprising at least one selected from the group consisting of a constitutional unit (G) derived from an aromatic diol and a constitutional unit (H) derived from an aromatic dicarboxylic acid. [6] The liquid crystal polyester resin according to any one of [1] to [5], having a melting point of 350 °C or lower. [7] The liquid crystal polyester resin according to [6], having a temperature difference between the melting point and the crystallization point of 30 °C or more. [8] A fibrous molded article containing the liquid crystal polyester resin according to any one of [1] to [7]. [9] A sheet-like molded article containing the liquid crystal polyester resin according to any one of [1] to [7].

[10] An injection molded article containing the liquid crystal polyester resin according to any one of [1] to [7].

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

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

[13] An electric and electronic component comprising the molded article according to

[10] .

Advantages of the Invention

[0010] According to the present invention, a liquid crystal polyester resin having a low dielectric 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 article can be improved. Therefore, when processing and molding and using as a product, it is possible to prevent a deterioration in the quality of the output signal in electric and electronic devices and communication devices that use high-frequency signals. Mode 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 acids in all structural units, and further contains at least one selected from structural units derived from aromatic monools, structural units derived from aromatic monoamines, and structural units derived from aromatic monocarboxylic acids. In the present invention, by satisfying the configurations 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 the first embodiment of the present invention, the liquid crystal polyester resin is characterized by having the following specific properties (dielectric tangent, anisotropy, melting point, melt viscosity).

[0013] The upper limit value of the dielectric tangent of the liquid crystal polyester resin according to the present invention at a measurement frequency of 10 GHz is 1.0×10 -3 or less, preferably 0.96×10 -3 or less, more preferably 0.93×10 -3 or less, still more preferably 0.90×10 -3 or less. By setting the dielectric tangent of the liquid crystal polyester resin according to the present invention within the above numerical range, a molded article having a low dielectric tangent can be produced, so that when used as a product, it is possible to prevent a deterioration in the quality of the output signal in electric and electronic devices and communication devices that use high-frequency signals. In addition, in this specification, the dielectric tangent 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 manufactured by Keysight Technologies, Inc.

[0014] The upper limit value of the absolute value of the difference (anisotropy) in the molding shrinkage rate between the flow direction (MD) and the direction perpendicular to the flow direction (TD) of the injection molded piece of the liquid crystal polyester resin according to the present invention is 1.00 or less, preferably 0.99 or less, more preferably 0.98 or less, and even more preferably 0.97 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 the molded product produced using the liquid crystal polyester resin can be improved. In addition, in this specification, the anisotropy of the liquid crystal polyester resin is the difference in the molding shrinkage rate (TD molding shrinkage rate - MD molding shrinkage rate) calculated from the measurement results of the molding shrinkage rates (%) of MD and TD of a flat plate test piece of 50 mm × 50 mm × 1 mm obtained by heating and melting the liquid crystal polyester resin at the melting point to the melting point + 20°C.

[0015] Considering heat resistance, the lower limit value of the melting point of the liquid crystal polyester resin according to the present invention is 280°C or higher, preferably 285°C or higher, more preferably 290°C or higher, even more preferably 295°C or higher, even more preferably 300°C or higher, and most preferably 305°C or higher. Also, the upper limit value is not particularly limited, and it 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 the molded product produced using the liquid crystal polyester resin against heat processing can be improved.

[0016] At the melting point of the liquid crystal polyester resin according to the present invention to the melting point + 20 ° C, the lower limit value of the melt viscosity measured under the condition of 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, still more preferably 37 Pa·s or more, and even more preferably 40 Pa·s or more. Further, the upper limit value is preferably 1000 Pa·s or less, more preferably 500 Pa·s or less, still more preferably 200 Pa·s or less, and even more preferably 150 Pa·s or less. By setting the melt viscosity of the liquid crystal polyester resin according to the present invention within the above numerical range, the dielectric loss tangent can be made lower, and further the mechanical strength of the molded product can be improved. In addition, 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 the 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 at least one selected from a structural unit (D) derived from an aromatic monool, a structural unit (E) derived from an aromatic monoamine, and a structural unit (F) derived from an aromatic monocarboxylic acid. Further, the liquid crystal polyester resin may further contain at least one selected from the group consisting of a structural unit (G) derived from an aromatic diol and a structural unit (H) derived from an aromatic dicarboxylic acid. The composition ratio (mol%) of the structural units (A) to (F) satisfies 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% 0.01 mol% ≤ structural unit (D) + structural unit (E) + structural unit (F) ≤ 5 mol% It is characterized by satisfying the above.

[0018] The liquid crystal polyester resin according to the present invention preferably satisfies the following conditions for the composition ratio (mol%) of the constituent units (A) to (F): 15 mol% ≤ constituent unit (A) ≤ 33 mol% 55 mol% ≤ constituent unit (B) ≤ 83 mol% 0.05 mol% ≤ constituent unit (C) ≤ 12 mol% 0.03 mol% ≤ constituent unit (D) + constituent unit (E) + constituent unit (F) ≤ 4 mol% more preferably satisfies: 18 mol% ≤ constituent unit (A) ≤ 30 mol% 60 mol% ≤ constituent unit (B) ≤ 80 mol% 0.1 mol% ≤ constituent unit (C) ≤ 10 mol% 0.05 mol% ≤ constituent unit (D) + constituent unit (E) + constituent unit (F) ≤ 3 mol% even more preferably satisfies: 19 mol% ≤ constituent unit (A) ≤ 29 mol% 65 mol% ≤ constituent unit (B) ≤ 78 mol% 0.5 mol% ≤ constituent unit (C) ≤ 8 mol% 0.1 mol% ≤ constituent unit (D) + constituent unit (E) + constituent unit (F) ≤ 2 mol% and particularly preferably satisfies: 20 mol% ≤ constituent unit (A) ≤ 28 mol% 67 mol% ≤ constituent unit (B) ≤ 75 mol% 1 mol% ≤ constituent unit (C) ≤ 5 mol% 0.2 mol% ≤ constituent unit (D) + constituent unit (E) + constituent unit (F) ≤ 1 mol% In addition, the liquid crystal polyester resin of the second embodiment preferably has the specific properties (dielectric tangent, anisotropy, melting point, melt viscosity) described in the first embodiment.

[0019] Furthermore, the liquid crystal polyester resins of the first and second embodiments preferably have the following specific property (temperature difference between melting point and 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, still more preferably 230 °C or higher, and even more preferably 240 °C or higher. The upper limit is preferably 300 °C or lower, more preferably 295 °C or lower, still more preferably 290 °C or lower, and even more preferably 280 °C or lower. The lower limit of the temperature difference (= "melting point (°C)" - "crystallization point (°C)") between the melting point and the crystallization point of the liquid crystal polyester resin according to the present invention is preferably 30 °C or higher, more preferably 35 °C or higher, still more preferably 40 °C or higher. The upper limit is preferably 80 °C or lower, more preferably 70 °C or lower, still more preferably 60 °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 melt-molding the liquid crystal polyester, sufficient time can be taken from when the liquid crystal polyester melts until 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, after heating the liquid crystal polyester resin from room temperature to 340 - 360 °C at a heating rate of 10 °C / min to completely melt it, the peak of the exothermic peak obtained when cooling to 30 °C at a rate of 10 °C / min is defined as the crystallization point (Tc), and the peak of the endothermic peak obtained when heating 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 (trade name: BH-2) manufactured by Olympus Corporation equipped with a microscope hot stage (trade name: FP82HT) manufactured by Mettler, etc., heating and melting the liquid crystal polyester resin on the microscope heating stage, and then observing the presence or absence of optical anisotropy.

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

[0023] (Constituent unit (A) derived from aromatic hydroxycarboxylic acid) The constituent unit (A) derived from aromatic hydroxycarboxylic acid is a constituent unit derived from p-hydroxybenzoic acid (HBA). Examples of the monomer that gives the constituent unit (A) include p-hydroxybenzoic acid, and its acetylated product, ester derivative, acid halide, etc.

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

[0025] (Constituent unit (B) derived from aromatic hydroxycarboxylic acid) The constituent unit (B) derived from aromatic hydroxycarboxylic acid is a constituent unit derived from 6-hydroxy-2-naphthoic acid (HNA). Examples of the monomer that gives the constituent unit (B) include 6-hydroxy-2-naphthoic acid, and its acetylated product, ester derivative, acid halide, etc.

[0026] The composition ratio (mol%) of the constituent unit (B) in the liquid crystal polyester resin is preferably 50 mol% or more and 85 mol% or less. From the viewpoints of reducing the dielectric loss tangent and improving the dimensional stability of the liquid crystal polyester resin, the lower limit value of the composition ratio (mol%) of the constituent unit (B) is preferably 55 mol% or more, more preferably 60 mol% or more, still more preferably 65 mol% or more, and even more preferably 67 mol% or more. Also, the upper limit value is preferably 83 mol% or less, more preferably 80 mol% or less, still more preferably 78 mol% or less, and even more preferably 75 mol% or less.

[0027] (Constituent unit (C) derived from aromatic hydroxycarboxylic acid) The constituent unit (C) derived from aromatic hydroxycarboxylic acid is not particularly limited as long as it is a constituent unit derived from a hydroxycarboxylic acid other than the constituent units (A) and (B). The constituent unit (C) is preferably a constituent 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. Among these, 4-(4-hydroxyphenyl)benzoic acid, 6-hydroxynicotinic acid, and m-hydroxybenzoic acid are more preferable. Examples of the monomer that gives the constituent unit (C) include these monomers, and their acetylated products, ester derivatives, acid halides, etc.

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

[0029] (Constituent unit (D) derived from aromatic monool) The constituent unit (D) derived from aromatic monool is preferably a constituent unit derived from an aromatic monool represented by the following formula (1). Note that only one kind of the constituent unit (D) may be included, or two or more kinds may be included.

[0030] [Chemical formula] In the above formula, Ar 1 is a monovalent hydrocarbon group having an aromatic ring which may optionally have a substituent. Examples of the hydrocarbon group 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 the substituent include hydrogen, an alkyl group, an alkoxy group, and fluorine. The number of carbon atoms of the alkyl group is preferably from 1 to 10, more preferably from 1 to 5. Further, it may be a linear alkyl group or a branched alkyl group. The number of carbon atoms of the alkoxy group is preferably from 1 to 10, more preferably from 1 to 5.

[0031] Examples of the monomer that gives the structural unit (D) include phenol (PH), cresol, naphthol, phenylphenol, and their acylates, ester derivatives, acid halides, and the like.

[0032] (Structural unit (E) derived from an aromatic monoamine) The structural unit (E) derived from an aromatic monoamine is preferably a structural unit derived from an aromatic monoamine represented by the following formula (2). Note that only one kind of the structural unit (E) may be included, or two or more kinds may be included.

[0033] [Chemical formula] In the above formula, Ar 2is a monovalent hydrocarbon group having an aromatic ring, which may have a substituent if desired. Examples of the hydrocarbon group 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 the substituent include hydrogen, an alkyl group, an alkoxy group, and fluorine. The number of carbon atoms of the alkyl group is preferably from 1 to 10, more preferably from 1 to 5. Also, it may be a linear alkyl group or a branched alkyl group. The number of carbon atoms of the alkoxy group is preferably from 1 to 10, more preferably from 1 to 5.

[0034] Examples of the monomer that provides the structural unit (E) include aniline, naphthylamine, phenylaniline, methylaniline, and their acylates, ester derivatives, acid halides, and the like.

[0035] (Structural unit (F) derived from an aromatic monocarboxylic acid) The structural unit (F) derived from an aromatic monocarboxylic acid is preferably a structural unit derived from an aromatic monocarboxylic acid represented by the following formula (3). Note that only one kind of the structural unit (F) may be included, or two or more kinds may be included.

[0036] [Chemical formula] In the above formula, Ar 3 is a monovalent hydrocarbon group having an aromatic ring, which may have a substituent if desired. Examples of the hydrocarbon group 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 the substituent include hydrogen, an alkyl group, an alkoxy group, and fluorine. The number of carbon atoms of the alkyl group is preferably from 1 to 10, more preferably from 1 to 5. Also, it may be a linear alkyl group or a branched alkyl group. The number of carbon atoms of the alkoxy group is preferably from 1 to 10, more preferably from 1 to 5.

[0037] Examples of the monomer that provides the structural unit (F) include benzoic acid (BA), naphthoic acid, phenylbenzoic acid, methylbenzoic acid, and their acyl compounds, ester derivatives, acid halides, and the like.

[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 viewpoints of reducing the dielectric loss tangent and improving the dimensional stability of the liquid crystal polyester resin, the lower limit value 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, still more preferably 0.1 mol% or more, and even more preferably 0.2 mol% or more. The upper limit value is preferably 4 mol% or less, more preferably 3 mol% or less, still more preferably 2 mol% or less, and even more preferably 1 mol% or less.

[0039] (Structural unit (G) derived from aromatic diol) The structural unit (G) derived from aromatic diol is preferably a structural unit derived from the aromatic diol represented by the following formula (4). Note that only one type or two or more types of the structural units derived from the structural unit (G) may be included.

[0040] [Chemical formula] In the above formula, Ar 4is a divalent hydrocarbon group having an aromatic ring, which may have a substituent if desired. Examples of the hydrocarbon group 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 the substituent include hydrogen, an alkyl group, an alkoxy group, and fluorine. The number of carbon atoms of the alkyl group is preferably from 1 to 10, more preferably from 1 to 5. The alkyl group may be linear or branched. The number of carbon atoms of the alkoxy group is preferably from 1 to 10, more preferably from 1 to 5.

[0041] Examples of the monomer that gives the structural unit (G) include 4,4-dihydroxybiphenyl (BP), hydroquinone (HQ), methylhydroquinone (MeHQ), 4,4'-isopropylidenediphenol (BisPA), and their acylates, ester derivatives, acid halides, and the like.

[0042] From the viewpoints of reducing the dielectric loss tangent and improving the dimensional stability of the liquid crystal polyester resin, the composition ratio (mol%) of the structural unit (G) in the liquid crystal polyester resin is preferably 2 mol% or less, more preferably 1 mol% or less, still more preferably 0.5 mol% or less, even more preferably 0.1 mol% or less, and may be 0 mol%.

[0043] (Structural unit (H) derived from an aromatic dicarboxylic acid) The structural unit (H) derived from an aromatic dicarboxylic acid is preferably a structural unit derived from an aromatic dicarboxylic acid represented by the following formula (5). Note that only one kind of the structural unit (H) may be included, or two or more kinds may be included.

[0044] [Chemical formula] In the above formula, Ar 5is a divalent hydrocarbon group having an aromatic ring, which may have a substituent if desired. Examples of the hydrocarbon group 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 the substituent include hydrogen, an alkyl group, an alkoxy group, and fluorine. The number of carbon atoms of the alkyl group is preferably from 1 to 10, more preferably from 1 to 5. Also, it may be a linear alkyl group or a branched alkyl group. The number of carbon atoms of the alkoxy group is preferably from 1 to 10, more preferably from 1 to 5.

[0045] Examples of the monomer that gives the structural unit (H) include terephthalic acid (TPA), isophthalic acid (IPA), 2,6-naphthalenedicarboxylic acid (NADA), and their acylates, ester derivatives, acid halides, etc.

[0046] From the viewpoints of reducing the dielectric loss tangent and improving the dimensional stability of the liquid crystal polyester resin, the composition ratio (mol%) of the structural unit (H) in the liquid crystal polyester resin is preferably 2 mol% or less, more preferably 1 mol% or less, still more preferably 0.5 mol% or less, even more preferably 0.1 mol% or less, and may be 0 mol%.

[0047] (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) including a step of obtaining a polymer by melt-polymerizing each monomer that gives the structural units (A) to (C), at least one monomer that gives the structural units (D) to (F), and, if necessary, at least one monomer that gives the structural units (G) to (H), and a step of obtaining a liquid crystal polyester resin by subjecting the polymer to solid-phase polymerization.

[0048] From the perspective of efficiently obtaining a liquid crystal polyester resin, melt polymerization is preferably carried out under reflux of acetic acid in the presence of 1.03 to 1.15 molar equivalents of acetic anhydride with respect to all the hydroxyl groups possessed by all the monomers, and more preferably in the presence of 1.03 to 1.10 molar equivalents of acetic anhydride under reflux of acetic acid.

[0049] The reaction temperature of the melt polymerization is preferably in the temperature range of the melting point to (the melting point + 70) °C, and more preferably in the temperature range of (the melting point + 20) °C to (the melting point + 50) °C.

[0050] Melt polymerization is preferably carried out in the presence of a catalyst and without a solvent. As the catalyst, those conventionally known as polymerization catalysts for polymers 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, antimony trioxide, etc., nitrogen-containing heterocyclic compounds such as N-methylimidazole, etc., and organic compound catalysts. The usage amount of the catalyst is not particularly limited, but it is preferably (10 to 100) mg / mol of the total number of moles of the monomers.

[0051] When performing solid-phase polymerization, the polymer obtained by melt polymerization may be pulverized into a powder or flake form after cooling and solidification. Alternatively, the polymer strand obtained by melt polymerization may be pelletized into a pellet form. The reaction temperature of the solid-phase polymerization is preferably below the melting point, and preferably (the melting point - 30) °C to (the melting point - 10) °C. The solid-phase polymerization may be carried out with stirring or in a stationary state without stirring.

[0052] The polymerization reactor is not particularly limited, but a reactor used for the reaction of general high-viscosity fluids is preferably used. Examples of these reactors include, for example, a stirring tank type polymerization reactor having a stirring device with various shapes of stirring blades such as an anchor type, multi-stage type, spiral ribbon type, spiral shaft type, etc., or a kneading device generally used for resin kneading such as a kneader, a roll mill, a Banbury mixer, etc.

[0053] <(Molded product)> The molded product according to the present invention contains a liquid crystal polyester resin and may further contain a filler.

[0054] <(Filler)> Examples of the filler include carbon fiber (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, and the like. These fillers may be used alone or in combination of two or more.

[0055] The content of the filler in the molded product 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, still 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 product. When two or more fillers are included, it is preferable that their total content is within the above range. If the content of the filler in the molded product is within the above range, a molded product with more excellent mechanical properties can be obtained, which is preferable.

[0056] <(Other resins)> The molded article according to the present invention may contain other resins other than the liquid crystal polyester resin without departing from the gist 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; polyphenylene ether resins; polyacetal resins; polyamide resins; imide resins such as polyimide and polyetherimide; 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; fluorine resins; and polycarbonate resins. These other resins may be used alone or in combination of two or more.

[0057] The content of other resins other than the liquid crystal polyester resin in the molded article is preferably 10 parts by mass or less, more preferably 5 parts by mass or less, based on 100 parts by mass of the liquid crystal polyester resin, as the upper limit.

[0058] (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, ultraviolet absorbers, antistatic agents, and surfactants without departing from the gist of the present invention. These other additives may be used alone or in combination of two or more.

[0059] The shape of the molded article is appropriately changed according to the application and is not particularly limited. Examples of the shape of the molded article include fibrous, plate-like, sheet-like, and rod-like.

[0060] 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 resin. As the molding method, for example, any method such as melt spinning method, solution spinning method, injection molding method, compression molding method, injection compression molding method, calender molding, punching molding, etc. may be used.

[0061] (Electrical and electronic components) The electrical and electronic component according to the present invention comprises a molded article containing a liquid crystal polyester resin (for example, a fibrous molded article or an injection molded article). Examples of the electrical and electronic component comprising the above molded article include antennas, high-speed transmission connectors, CPU sockets, circuit boards, flexible printed circuits used in electronic devices and communication devices such as ETC, GPS, wireless LAN, and mobile phones. (FPC), laminated circuit boards, millimeter wave and quasi-millimeter wave radars such as collision prevention radars, RFID tags, capacitors, inverter components, cable coating materials, insulating materials for secondary batteries such as lithium ion batteries, speaker diaphragms, etc.

Examples

[0062] Hereinafter, the present invention will be described more specifically by way of examples, but the present invention is not limited to the examples.

[0063] <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 4-(4-hydroxyphenyl)benzoic acid (HPBA), 0.5 mol% of phenol (PH), and 0.5 mol% of terephthalic acid (TPA) were added to a polymerization vessel equipped with a stirring blade, potassium acetate was charged as a catalyst, and the polymerization vessel was depressurized and nitrogen-injected three times. After that, acetic anhydride (1.05 molar equivalents relative to the hydroxyl group) was further added, the temperature was raised to 150 ° C., and an acetylation reaction was carried out for 2 hours in a reflux state.

[0064] After the acetylation was completed, the polymerization vessel in a state where acetic acid was distilled off was heated at 0.5 °C / min until the molten zone temperature in the tank reached 310 °C. Thereafter, the polymer was taken out and cooled and solidified. The obtained polymer was pulverized to a size that passed through a sieve with an opening of 2.0 mm to obtain a polymer. Next, the obtained polymer was heated from room temperature to 300 °C using an oven heater manufactured by Yamato Scientific Co., Ltd. and then held for 2 hours to perform solid-phase polymerization.

[0065] Thereafter, the polymer was naturally cooled at room temperature to obtain the polyester resin of the present invention. Using a polarizing microscope (trade name: BH-2) manufactured by Olympus Corporation equipped with a microscope hot stage (trade name: FP82HT) manufactured by Mettler, the polyester resin was heated and melted on the microscope heating stage, and the liquid crystallinity was confirmed from the presence or absence of optical anisotropy.

[0066] (Example 2) A polyester resin was obtained in the same manner as in Example 1 except that the monomer charge was changed to 24 mol% of HBA, 73 mol% of HNA, 2 mol% of HPBA, 0.5 mol% of PH, and 0.5 mol% of isophthalic acid (IPA). Next, in the same manner as above, the liquid crystallinity of the polyester resin was confirmed.

[0067] (Example 3) A polyester resin was obtained in the same manner as in Example 1 except that the monomer charge was changed to 27 mol% of HBA, 70 mol% of HNA, 2 mol% of HPBA, 0.5 mol% of PH, and 0.5 mol% of IPA. Next, in the same manner as above, the liquid crystallinity of the polyester resin was confirmed.

[0068] (Example 4) m-Hydroxybenzoic acid (HPBA) A polyester resin was obtained in the same manner as in Example 1 except that the monomer charge was changed to 24.5 mol% of HBA, 73 mol% of HNA, 2 mol% of HPBA, and 0.5 mol% of benzoic acid (BA). Next, in the same manner as above, the liquid crystallinity of the polyester resin was confirmed.

[0069] (Example 5) A polyester resin was obtained in the same manner as in Example 1, except that the monomer charge was changed to 24.5 mol% of HBA, 73 mol% of HNA, 2 mol% of m-hydroxybenzoic acid (mHBA), and 0.5 mol% of PH. Next, the liquid crystallinity of the polyester resin was confirmed in the same manner as above.

[0070] (Example 6) A polyester resin was obtained in the same manner as in Example 1, except that the monomer charge was changed to 22.5 mol% of HBA, 72 mol% of HNA, 5 mol% of mHBA, and 0.5 mol% of BA. Next, the liquid crystallinity of the polyester resin was confirmed in the same manner as above.

[0071] (Comparative Example 1) A polyester resin was obtained in the same manner as in Example 1, except that the monomer charge was 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.

[0072] (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% of HBA, 20 mol% of BP, 15 mol% of TPA, and 5 mol% of isophthalic acid (IPA). Next, the liquid crystallinity of the polyester resin was confirmed in the same manner as above.

[0073] (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% of HBA, 40 mol% of HNA, 27 mol% of BP, and 27 mol% of NADA. Next, the liquid crystallinity of the polyester resin was confirmed in the same manner as above.

[0074] (Comparative Example 4) A polyester resin was obtained in the same manner as in Example 1, except that the monomer charge was changed to 35 mol% of HBA, 50 mol% of HNA, and 15 mol% of 4-acetamidobenzoic acid (ABA). Next, the liquid crystallinity of the polyester resin was confirmed in the same manner as above.

[0075] (Comparative Example 5) A polyester resin was obtained in the same manner as in Example 1, except that the monomer charge was changed to 19 mol% of HBA, 79 mol% of HNA, and 2 mol% of mHBA. Next, the liquid crystallinity of the polyester resin was confirmed in the same manner as above.

[0076] (Comparative Example 6) A polyester resin was obtained in the same manner as in Example 1, except that the monomer charge was changed to 23.8 mol% of HBA, 75.5 mol% of HNA, and 0.7 mol% of IPA. Next, the liquid crystallinity of the polyester resin was confirmed in the same manner as above.

[0077] (Comparative Example 7) A polyester resin was obtained in the same manner as in Example 1, except that the monomer charge was changed to 14.9 mol% of HBA, 84.4 mol% of HNA, and 0.7 mol% of IPA. Next, the liquid crystallinity of the polyester resin was confirmed in the same manner as above.

[0078] (Comparative Example 8) A polyester resin was obtained in the same manner as in Example 1, except that the monomer charge was changed to 23.8 mol% of HBA, 75.5 mol% of HNA, and 0.7 mol% of TPA. Next, the liquid crystallinity of the polyester resin was confirmed in the same manner as above.

[0079] (Comparative Example 9) A polyester resin was obtained in the same manner as in Example 1, except that the monomer charge was changed to 18 mol% of HBA, 81 mol% of HNA, and 1 mol% of BP. Next, the liquid crystallinity of the polyester resin was confirmed in the same manner as above.

[0080] (Comparative Example 10) A polyester resin was obtained in the same manner as in Example 1, except that the monomer charge was changed to 21 mol% of HBA, 78 mol% of HNA, 0.5 mol% of BP, and 0.5 mol% of TPA. Next, the liquid crystallinity of the polyester resin was confirmed in the same manner as above.

[0081] (Comparative Example 11) A polyester resin was obtained in the same manner as in Example 1, except that the monomer charge was 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.

[0082] (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.

[0083] (Comparative Example 13) A polyester resin was obtained in the same manner as in Example 1, except that the monomer charge was 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.

[0084] (Measurement of Melting Point and Crystallization Point) The melting point and crystallization point 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 Sciences 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, and then the peak of the exothermic peak obtained when cooling to 30 °C at a rate of 10 °C / min was taken as the crystallization point (Tc), and the peak of the endothermic peak obtained when heating to 380 °C at a rate of 10 °C / min was taken as the melting point (Tm). Also, the difference between the melting point and the crystallization point was calculated from the obtained melting point and crystallization point. The melting point (Tm), crystallization point (Tc), and the difference between the melting point and the crystallization point (Tm - Tc) are shown in Table 1.

[0085] (Preparation of Flat Test Specimen A) The liquid crystal polyester resins obtained in the examples and comparative examples were heated and melted at a temperature from the melting point to the melting point + 20 °C and injection molded to prepare flat test specimens A with dimensions of 30 mm × 30 mm × 0.4 mm.

[0086] (Preparation of Flat Test Specimen B) The liquid crystal polyester resins obtained in the examples and comparative examples were heated and melted under the conditions of melting point to melting point + 20 °C, and injection molded to produce flat test pieces B with dimensions of 50 mm × 50 mm × 1 mm.

[0087] <Measurement of dielectric loss tangent (10 GHz)> Regarding the in-plane dielectric loss tangent (tanδ) of the flat test piece A produced above, the dielectric loss tangent at a frequency of 10 GHz was measured by the split post dielectric resonator method (SPDR method) using a network analyzer N5247A from Keysight Technologies. The measurement results are shown in Table 1.

[0088] <Measurement of anisotropy> The molding shrinkage rates (%) in the flow direction (MD) and the direction perpendicular to the flow direction (TD) of the flat test piece B produced above were measured, and the difference between these molding shrinkage rates (molding shrinkage rate in TD - molding shrinkage rate in MD) was calculated to evaluate the anisotropy. The calculation results are shown in Table 1. The smaller the value of the difference, the smaller the anisotropy.

[0089] <Measurement of melt viscosity> At the melting point + 20 °C of the liquid crystal polyester resins obtained in the examples and comparative examples, the melt viscosities (Pa·s) under each condition of a shear rate of 1000 / s were measured using a capillary rheometer viscometer (Capirograph 1D manufactured by Toyo Seiki Seisaku-sho, Ltd.) and a capillary with an inner diameter of 1 mm in accordance with JIS K7199. The measurement results are shown in Table 1.

[0090] As is clear from the results in Table 1, the liquid crystal polyester resins of Examples 1 to 6 had a low dielectric loss tangent, a high melting point and excellent heat resistance, and a small anisotropy and excellent dimensional stability.

[0091]

Table 1

Claims

1. A liquid crystal polyester resin comprising 90 mol% or more of a structural unit derived from an aromatic hydroxycarboxylic acid based on all structural units, wherein the liquid crystal polyester resin further contains at least one selected from a structural unit derived from an aromatic monool, a structural unit derived from an aromatic monoamine, and a structural unit derived from an aromatic monocarboxylic acid, The dielectric loss tangent at a measurement frequency of 10 GHz is 1.0×10 －３ or less, wherein the difference (anisotropy) in the molding shrinkage rate between the flow direction (MD) and the direction perpendicular to the flow direction (TD) of the injection molded piece of the liquid crystal polyester resin is 1.00 or less, wherein the melting point of the liquid crystal polyester resin is 280 °C or higher, and the melt viscosity measured at a shear rate of 1000 / s at a temperature from the melting point of the liquid crystal polyester resin to the melting point + 20 °C is 25 Pa·s or higher. A liquid crystal polyester resin characterized by the above.

2. A liquid crystal polyester resin comprising 90 mol% or more of a structural unit derived from an aromatic hydroxycarboxylic acid based on all structural units, wherein the aromatic hydroxycarboxylic acid contains 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), wherein the liquid crystal polyester resin further contains at least one selected from a structural unit (D) derived from an aromatic monool, a structural unit (E) derived from an aromatic monoamine, and a structural unit (F) derived from an aromatic monocarboxylic acid, and the composition ratio (mol%) of the structural units (A) to (F) satisfies 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% 0.01 mol% ≤ structural unit (D) + structural unit (E) + structural unit (F) ≤ 5 mol% A liquid crystal polyester resin characterized by the above.

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 constitutional unit (C) is a constitutional 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 claim 2, further comprising at least one selected from the group consisting of a constitutional unit (G) derived from an aromatic diol and a constitutional unit (H) derived from an aromatic dicarboxylic acid.

6. The liquid crystal polyester resin according to any one of claims 1 to 5, having a melting point of 350 °C or lower.

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

8. A fibrous molded article comprising the liquid crystal polyester resin according to any one of claims 1 to 5.

9. A sheet-like molded article comprising the liquid crystal polyester resin according to any one of claims 1 to 5.

10. An injection molded article comprising the liquid crystal polyester resin according to any one of claims 1 to 5.

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

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

13. An electric and electronic component comprising the molded article according to claim 10.

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