Liquid crystalline resin and liquid crystalline resin composition

Abstract

To provide a liquid crystalline resin having a low dielectric constant and low dielectric loss tangent while maintaining a high melting point and to provide a liquid crystalline resin composition comprising the same.SOLUTION: There is provided a liquid crystalline resin which shows optical anisotropy during melting and contains structural units (I) to (III) and optionally contains structural units (IV) and (V), wherein for all structural units, the content of (I) is 2.5 to 35 mol%, the content of (II) is 25 to 55 mol%, the content of (III) is 15 to 37.5 mol%, the content of (IV) is 0 to 35 mol% and the content of (V) is 0 to 15 mol%. (I): a cyclohexanedicarboxylic acid unit, (II) 6-hydroxy-2-naphthoic acid, (III): -X-Ar1-Y-, (IV) -C(=O)-Ar2-C(=O)-, (V): 4-hydroxybenzoic acid. (Wherein, Ar1 and Ar2 each independently represent a phenylene group, a naphthylene group, or a biphenylene group, X and Y each independently represent an oxygen atom or an imino group.)SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a liquid crystalline resin and a liquid crystalline resin composition. [Background technology]

[0002] Liquid crystalline resins have a good balance of excellent mechanical strength, heat resistance, chemical resistance, electrical properties, etc., and also have excellent dimensional stability, making them widely used as high-performance engineering plastics. Meanwhile, in recent years, remarkable technological developments have been made in the information and communications field, including mobile phones, wireless LANs, and ITS technologies such as GPS, VICS (registered trademark), and ETC. Accordingly, there is a growing need for high-performance electronic components that can be used in high-frequency ranges such as microwaves and millimeter waves. Materials constituting such electronic components are required to have appropriate dielectric properties depending on the design of each electronic component.

[0003] For example, Patent Document 1 discloses that a liquid crystal polyester containing a specific amount of structural units derived from cyclohexanedicarboxylic acid has improved dielectric properties. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Special Publication No. 2023-553302 Summary of the Invention [Problem to be solved by the invention]

[0005] However, according to the investigations of the present inventors, it has been found that when the content of structural units derived from cyclohexanedicarboxylic acid in a liquid crystalline resin is increased in order to improve the dielectric properties, the dielectric constant tends to decrease, while the dielectric loss tangent tends to increase and the melting point tends to decrease.

[0006] In view of the above problems, an object of the present invention is to provide a liquid crystalline resin having a low dielectric constant and a low dielectric loss tangent while maintaining a high melting point, and a liquid crystalline resin composition containing the same. [Means for solving the problem]

[0007] The present inventors have conducted extensive research to solve the above-mentioned problems. As a result, they have found that the above-mentioned problems can be solved by a liquid crystalline resin that contains a structural unit derived from cyclohexanedicarboxylic acid, a structural unit derived from 6-hydroxy-2-naphthoic acid, and a structural unit derived from an arenediol, arenediamine, or hydroxyarylamine, and that may or may not contain a structural unit derived from an arylenedicarboxylic acid and a structural unit derived from 4-hydroxybenzoic acid, and that the content of each structural unit is within a specific range. This finding led to the completion of the present invention. More specifically, the present invention provides the following.

[0008] (1) A liquid crystalline resin that exhibits optical anisotropy when melted, The liquid crystalline resin contains the following structural units (I), (II), and (III), and may or may not contain the following structural units (IV) and (V), the content of the structural unit (I) is 2.5 to 35 mol % based on all structural units, the content of the structural unit (II) is 25 to 55 mol % based on all structural units; The content of the structural unit (III) is 15 to 37.5% of all structural units, the content of the structural unit (IV) is 0 to 35 mol % based on all structural units; The content of the structural unit (V) is 0 to 15 mol % based on all structural units. Liquid crystalline resin.

[0009] [ka] (In the formula, Ar1 and Ar2 each independently represent a phenylene group, a naphthylene group, or a biphenylylene group. X and Y each independently represent an oxygen atom or an imino group.)

[0010] (2) The liquid crystal resin according to (1), wherein the total content of the structural units (I) to (V) is 100 mol % based on all the structural units.

[0011] (3) The liquid crystalline resin according to any one of (1) to (3), wherein the structural unit (I) is derived from one or more structural units selected from the group consisting of 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, and derivatives thereof.

[0012] (4) A liquid crystal resin composition comprising the liquid crystal resin according to any one of (1) to (3).

[0013] (5) A molded article made of the liquid crystalline resin according to any one of (1) to (3).

[0014] (6) A molded article made of the liquid crystal resin composition according to (4). [Effects of the Invention]

[0015] According to the present invention, it is possible to provide a liquid crystalline resin having a low dielectric constant and a low dielectric loss tangent while maintaining a high melting point, and a liquid crystalline resin composition containing the same. [Brief explanation of the drawings]

[0016] [Figure 1] FIG. 1 is a top view showing the cutting positions of the test pieces for evaluating dielectric characteristics used in the examples and comparative examples. DETAILED DESCRIPTION OF THE INVENTION

[0017] Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to the following embodiments.

[0018] <Liquid Crystalline Resin> The liquid crystal resin of the present invention contains the following structural units (I), (II), and (III), and may or may not contain the following structural units (IV) and (V).

[0019] [ka]

[0020] The structural unit (I) is derived from, for example, 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, or 1,2-cyclohexanedicarboxylic acid (hereinafter also referred to as "1,4-CHDA," "1,3-CHDA," or "1,2-CHDA," respectively). From the viewpoint of a balance between a high melting point, a low dielectric constant, and a low dielectric dissipation factor, it is preferably derived from 1,4-cyclohexanedicarboxylic acid or 1,3-cyclohexanedicarboxylic acid. That is, examples of the structural unit (I) include structural units derived from one or more selected from the group consisting of 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, and derivatives thereof. From the viewpoint of a balance between a high melting point, a low dielectric constant, and a low dielectric dissipation factor, structural units derived from one or more selected from the group consisting of 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, and derivatives thereof are preferred. Hereinafter, a monomer from which the structural unit (I) is derived, such as 1,2-CHDA, 1,3-CHDA, or 1,4-CHDA, will also be referred to as "monomer (I)." In the liquid crystal resin of the present invention, the structural unit (I) may be used alone or in combination of two or more types.

[0021] In the liquid crystalline resin of the present invention, the content of the structural unit (I) is 2.5 to 35 mol% based on all structural units. If the content of the structural unit (I) is less than 2.5 mol% or more than 35 mol%, at least one of a high melting point, a low dielectric constant, and a low dielectric dissipation factor is likely to be insufficient. From the viewpoint of a balance between a high melting point, a low dielectric constant, and a low dielectric dissipation factor, the content of the structural unit (I) is preferably 3.5 to 33 mol%, more preferably 4.5 to 31 mol%, and even more preferably 5 to 30 mol%.

[0022] The structural unit (II) is derived from, for example, 6-hydroxy-2-naphthoic acid (hereinafter also referred to as "HNA"). Hereinafter, a monomer from which the structural unit (II) is derived, such as HNA, is also referred to as monomer (II). In the liquid crystal resin of the present invention, the structural unit (II) may be used alone or in combination of two or more types.

[0023] In the liquid crystalline resin of the present invention, the content of the structural unit (II) is 25 to 55 mol% based on all structural units. If the content of the structural unit (II) is less than 25 mol% or more than 55 mol%, at least one of a high melting point, a low dielectric constant, and a low dielectric dissipation factor is likely to be insufficient. From the viewpoint of a balance between a high melting point, a low dielectric constant, and a low dielectric dissipation factor, the content of the structural unit (II) is preferably 27 to 55 mol%, more preferably 29 to 55 mol%, and even more preferably 30 to 55 mol%.

[0024] In the formula representing the structural unit (III), Ar1 may be, for example, a 1,2-phenylene group, a 1,3-phenylene group, a 1,4-phenylene group, a 2,6-naphthylene group, or a 4,4'-biphenylylene group. From the viewpoint of a balance between a high melting point, a low dielectric constant, and a low dielectric dissipation factor, 4,4'-biphenyl and 1,4-phenylene are preferred. Therefore, the structural unit (III) is derived from, for example, hydroquinone (hereinafter also referred to as "HQ"), 2,6-dihydroxynaphthalene, 4,4'-dihydroxybiphenyl (hereinafter also referred to as "BP"), or N-acetyl-p-aminophenol (hereinafter also referred to as "APAP"), and from the viewpoint of a balance between a high melting point, a low dielectric constant, and a low dielectric dissipation factor, 4,4'-dihydroxybiphenyl and N-acetyl-p-aminophenol are preferred. Hereinafter, a monomer from which the structural unit (III) is derived, such as HQ, BP, or APAP, will also be referred to as "monomer (III)." In the liquid crystal resin of the present invention, the structural unit (III) may be used alone or in combination of two or more types.

[0025] In the liquid crystalline resin of the present invention, the content of the structural unit (III) is 15 to 37.5 mol% relative to all structural units. If the content of the structural unit (III) is less than 15 mol% or more than 37.5 mol%, at least one of a high melting point, a low dielectric constant, and a low dielectric dissipation factor is likely to be insufficient. From the viewpoint of a balance between a high melting point, a low dielectric constant, and a low dielectric dissipation factor, the content of the structural unit (III) is preferably 17.5 to 35 mol%, more preferably 20 to 32.5 mol%, and even more preferably 22.5 to 30 mol%.

[0026] In the formula representing the structural unit (IV), Ar2 may be, for example, a 1,2-phenylene group, a 1,3-phenylene group, a 1,4-phenylene group, a 2,6-naphthylene group, or a 4,4'-biphenylylene group. From the viewpoint of a balance between a high melting point, a low dielectric constant, and a low dielectric dissipation factor, 1,4-phenylene is preferred. Therefore, the structural unit (IV) is derived from, for example, 1,3-phenylenedicarboxylic acid (hereinafter also referred to as "IA"), 1,4-phenylenedicarboxylic acid (hereinafter also referred to as "TA"), or 2,6-naphthalenedicarboxylic acid (hereinafter also referred to as "NDA"), and from the viewpoint of a balance between a high melting point, a low dielectric constant, and a low dielectric dissipation factor, 1,4-phenylenedicarboxylic acid is preferred. Hereinafter, the monomers from which the structural unit (IV), such as IA, TA, and NDA, are derived, are also referred to as "monomer (IV)." In the liquid crystal resin of the present invention, the structural unit (IV) may be used alone or in combination of two or more types.

[0027] In the liquid crystalline resin of the present invention, the content of the structural unit (IV) is 0 to 35 mol% relative to all structural units. If the content of the structural unit (IV) exceeds 35 mol%, at least one of a high melting point, a low dielectric constant, and a low dielectric dissipation factor tends to be insufficient. From the viewpoint of a balance between a high melting point, a low dielectric constant, and a low dielectric dissipation factor, the content of the structural unit (IV) is preferably 0 to 30 mol%, more preferably 0 to 25 mol%, and even more preferably 0 to 20 mol%.

[0028] The structural unit (V) is derived from, for example, 4-hydroxybenzoic acid (hereinafter also referred to as "4-HBA"). Hereinafter, a monomer from which the structural unit (V) is derived, such as 4-HBA, will also be referred to as monomer (V). In the liquid crystal resin of the present invention, the structural unit (V) may be used alone or in combination of two or more types.

[0029] In the liquid crystalline resin of the present invention, the content of the structural unit (V) is 0 to 15 mol% relative to all structural units. If the content of the structural unit (V) exceeds 15 mol%, at least one of a high melting point, a low dielectric constant, and a low dielectric dissipation factor is likely to be insufficient. From the viewpoint of a balance between a high melting point, a low dielectric constant, and a low dielectric dissipation factor, the content of the structural unit (V) is preferably 0 to 13 mol%, more preferably 0 to 11 mol%, and even more preferably 0 to 10 mol%.

[0030] As described above, the liquid crystalline resin of the present invention contains the structural units (I), (II), and (III), and may or may not contain the structural units (IV) and (V). The content of each of the structural units (I) to (V) is within a specific range relative to the total content of all structural units. This allows the resin to have a low dielectric constant and a low dielectric dissipation factor while maintaining a high melting point. More specifically, it is believed that the liquid crystalline resin of the present invention is likely to have a low dielectric constant because it contains a certain amount or more of the structural unit (I), which facilitates the dielectric constant-lowering effect of the cyclohexane skeleton. Furthermore, it is believed that the liquid crystalline resin of the present invention is likely to have a low dielectric dissipation factor because it contains a certain amount or more of the structural unit (II), which facilitates the dielectric dissipation factor-lowering effect of the naphthalene skeleton, which overcomes the dielectric dissipation factor-increasing effect of the cyclohexane skeleton. Furthermore, it is believed that the liquid crystalline resin of the present invention maintains a high melting point because the increase in melting point due to the combined content of structural units (II) and (V) does not exceed a certain amount, thereby exceeding the decrease in melting point due to the cyclohexane skeleton.

[0031] In the liquid crystalline resin of the present invention, the ratio of the structural unit (II) to the structural unit (V) is preferably 1.5 or more, more preferably 2.5 or more, and even more preferably 3 or more. When the ratio is 1.5 or more, the liquid crystalline resin tends to have a low dielectric loss tangent.

[0032] In the liquid crystalline resin of the present invention, the total content of the structural units (II) and (V) is preferably 57.5 mol% or less, more preferably 56 mol% or less, and even more preferably 55 mol% or less, based on all structural units. When the total content is 57.5 mol% or less, the liquid crystalline resin is likely to maintain a high melting point. The lower limit of the total content is 25 mol%, and from the viewpoint of a balance between a high melting point, a low dielectric constant, and a low dielectric loss tangent, it is preferably 29 mol%, more preferably 33 mol%, even more preferably 35 mol%, and even more preferably 40 mol%.

[0033] In the liquid crystalline resin of the present invention, from the viewpoint of a balance between a high melting point, a low dielectric constant, and a low dielectric dissipation factor, the total content of the structural units (I) to (V) is preferably 80 to 100 mol%, more preferably 90 to 100 mol%, even more preferably 95 to 100 mol%, and most preferably 100 mol%, based on all structural units. Therefore, the liquid crystalline resin of the present invention may contain a structural unit other than the structural units (I) to (V) (hereinafter also referred to as "structural unit (Z)"). In the liquid crystalline resin of the present invention, from the viewpoint of a balance between a high melting point, a low dielectric constant, and a low dielectric dissipation factor, the total content of the structural unit (Z) is preferably 0 to 20 mol%, more preferably 0 to 10 mol%, even more preferably 0 to 5 mol%, and most preferably 0 mol%, based on all structural units.

[0034] Examples of the structural unit (Z) include structural units derived from one or more selected from the group consisting of aliphatic chain dicarboxylic acids, alicyclic dicarboxylic acids other than the monomer (I), aliphatic chain diols, alicyclic diols, and derivatives thereof. Hereinafter, the monomer from which the structural unit (Z) is derived is also referred to as the monomer (Z). In the liquid crystal resin of the present invention, the structural unit (Z) may be used alone or in combination of two or more types.

[0035] Next, a method for producing the liquid crystalline resin of the present invention will be described. The liquid crystalline resin of the present invention is polymerized using a direct polymerization method, an ester exchange method, etc. For the polymerization, a melt polymerization method, a solution polymerization method, a slurry polymerization method, a solid phase polymerization method, etc., or a combination of two or more of these methods is used, and a melt polymerization method or a combination of a melt polymerization method and a solid phase polymerization method is preferably used.

[0036] Various catalysts can be used in these polymerizations, and representative examples include metal salt catalysts such as potassium acetate, magnesium acetate, stannous acetate, tetrabutyl titanate, lead acetate, sodium acetate, antimony trioxide, and tris(2,4-pentanedionato)cobalt(III), and organic compound catalysts such as 1-methylimidazole and 4-dimethylaminopyridine.

[0037] The reaction conditions are, for example, a reaction temperature of 200 to 380°C and a final ultimate pressure of 0.1 to 760 Torr (i.e., 13 to 101,080 Pa). In particular, in the case of a melting reaction, the reaction temperature is, for example, 260 to 380°C, preferably 300 to 360°C, and the final ultimate pressure is 1 to 100 Torr (i.e., 133 to 13,300 Pa), preferably 1 to 50 Torr (i.e., 133 to 6,670 Pa).

[0038] The reaction can be initiated by charging all raw material monomers (monomers (I) to (III), optionally monomer (IV), optionally monomer (V), and optionally monomer (Z)), an acylating agent, and a catalyst into the same reaction vessel (single-stage system), or by acylating the hydroxyl groups of monomer (II), optionally monomer (III) having a hydroxyl group, and optionally monomer (Z) having a hydroxyl group with an acylating agent, followed by reacting them with the carboxyl groups of monomer (I), monomer (II), monomer (IV), monomer (V), and optionally monomer (Z) having a carboxyl group (two-stage system).

[0039] The melt polymerization is carried out by starting pressure reduction and setting the pressure to a predetermined level after the reaction system has reached a predetermined temperature. After the torque of the stirrer has reached a predetermined value, an inert gas is introduced, and the pressure is increased from a reduced pressure state to normal pressure and then to a predetermined pressurized state, and the liquid crystalline resin is discharged from the reaction system.

[0040] The liquid crystalline resin produced by the above polymerization method can be further subjected to solid-state polymerization by heating in an inert gas at normal or reduced pressure to increase the molecular weight. Preferred conditions for the solid-state polymerization reaction are a reaction temperature of 230 to 350°C, preferably 260 to 330°C, and a final pressure of 10 to 760 Torr (i.e., 1,330 to 101,080 Pa).

[0041] Next, the properties of the liquid crystalline resin will be described. The liquid crystalline resin of the present invention exhibits liquid crystallinity, that is, optical anisotropy when melted.

[0042] In the present invention, the liquid crystalline resin exhibiting liquid crystallinity is an essential element for the liquid crystalline resin to have both thermal stability and easy processability. Although some resins containing the above structural units (I), (II), and (III) and containing or not containing the above structural units (IV) and (V) do not form an anisotropic molten phase depending on the structural components and the sequence distribution in the resin, the liquid crystalline resin of the present invention is limited to resins that exhibit optical anisotropy when melted.

[0043] The melt anisotropy can be confirmed by a conventional polarization inspection method using crossed polarizers. More specifically, melt anisotropy can be confirmed by melting a sample placed on a Linkam hot stage using an Olympus polarizing microscope and observing it at 150x magnification under a nitrogen atmosphere. Liquid crystal resins are optically anisotropic and transmit light when inserted between crossed polarizers. If a sample is optically anisotropic, polarized light will transmit even when it is in a molten, static liquid state, for example.

[0044] Nematic liquid crystalline resins experience a significant drop in viscosity above their melting point, so the ability to exhibit liquid crystallinity at or above their melting point is generally an indicator of processability. While a melting point as high as possible is preferable from the standpoint of heat resistance, a melting point of 318°C or higher is preferred, taking into account factors such as thermal degradation during melt processing of the liquid crystalline resin and the heating capacity of the molding machine. A melting point of 320 to 400°C is more preferred, and a melting point of 321 to 380°C is even more preferred.

[0045] The melt viscosity of the liquid crystalline resin of the present invention at a temperature 10 to 30°C higher than the melting point of the resin and at a shear rate of 1000 / sec is preferably 500 Pa·s or less, more preferably 0.5 to 300 Pa·s, and even more preferably 1 to 100 Pa·s. When the melt viscosity is within the above range, the liquid crystalline resin itself or a composition containing the liquid crystalline resin is likely to have sufficient fluidity during molding, and excessive filling pressure is unlikely to occur. In this specification, melt viscosity refers to the melt viscosity measured in accordance with ISO 11443.

[0046] <Liquid crystal resin composition> The liquid crystalline resin of the present invention may be blended with various fibrous, granular, or plate-like inorganic and organic fillers depending on the intended use.

[0047] The inorganic filler to be blended in the liquid crystal resin composition of the present invention may be in the form of fiber, granules or plates.

[0048] Examples of fibrous inorganic fillers include inorganic fibrous materials such as glass fiber, milled glass fiber, carbon fiber, asbestos fiber, silica fiber, silica-alumina fiber, alumina fiber, zirconia fiber, boron nitride fiber, silicon nitride fiber, boron fiber, potassium titanate fiber, silicate fibers such as wollastonite, magnesium sulfate fiber, aluminum borate fiber, and metal fibers such as stainless steel, aluminum, titanium, copper, brass, etc. A particularly representative fibrous filler is glass fiber.

[0049] Further, examples of granular inorganic fillers include carbon black, graphite, silica, quartz powder, glass beads, glass balloons, glass powder, calcium silicate, aluminum silicate, kaolin, clay, diatomaceous earth, silicates such as wollastonite, metal oxides such as iron oxide, titanium oxide, zinc oxide, antimony trioxide, and alumina, metal carbonates such as calcium carbonate and magnesium carbonate, metal sulfates such as calcium sulfate and barium sulfate, as well as ferrite, silicon carbide, silicon nitride, boron nitride, and various metal powders.

[0050] Examples of the plate-like inorganic filler include mica, glass flakes, talc, and various metal foils.

[0051] Examples of organic fillers include heat-resistant, high-strength synthetic fibers such as aromatic polyester fibers, liquid crystal polymer fibers, aromatic polyamide fibers, and polyimide fibers.

[0052] These inorganic and organic fillers can be used alone or in combination of two or more. The combination of a fibrous inorganic filler with a granular or plate-like inorganic filler is a preferred combination in terms of providing mechanical strength, dimensional accuracy, electrical properties, etc. Particularly preferred are glass fiber as the fibrous filler and mica and talc as the plate-like filler, and the total amount of these is preferably 120 parts by mass or less, more preferably 20 to 80 parts by mass, per 100 parts by mass of the liquid crystal resin. By combining glass fiber with mica or talc, the liquid crystal resin composition exhibits particularly significant improvements in heat distortion temperature, mechanical properties, etc.

[0053] When using these fillers, a sizing agent or a surface treatment agent may be used, if necessary.

[0054] As described above, the liquid crystalline resin composition of the present invention contains the liquid crystalline resin of the present invention as an essential component, and optionally contains an inorganic or organic filler, but may contain other components as long as the effects of the present invention are not impaired. Here, the other components may be any components, and examples thereof include additives such as other resins, antioxidants, stabilizers, pigments, and crystal nucleating agents.

[0055] The method for producing the liquid crystal resin composition of the present invention is not particularly limited, and the liquid crystal resin composition of the present invention can be prepared by a conventionally known method.

[0056] <Molded products> The molded article of the present invention is made from the liquid crystalline resin of the present invention or the liquid crystalline resin composition of the present invention. The molded article of the present invention can be obtained by molding the liquid crystalline resin of the present invention or the liquid crystalline resin composition of the present invention. The molding method is not particularly limited, and a general molding method can be used. Examples of general molding methods include injection molding, extrusion molding, compression molding, blow molding, vacuum molding, foam molding, rotational molding, and gas injection molding. The shape of the molded article is not particularly limited, and may be any desired shape.

[0057] A molded article made of the liquid crystalline resin of the present invention has a low dielectric constant and a low dielectric loss tangent. In addition, a molded article made of the liquid crystalline resin composition of the present invention has a low dielectric constant and, when containing an inorganic or organic filler, further improved mechanical strength, etc.

[0058] Preferred applications of the molded article of the present invention having the above-mentioned properties include electronic parts for use in high frequency ranges such as microwaves and millimeter waves. [Example]

[0059] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples.

[0060] Example 1 A polymerization vessel equipped with a stirrer, a reflux column, a monomer inlet, a nitrogen inlet, and a pressure reduction / outlet line was charged with the following raw material monomers and fatty acid metal salt catalyst, and nitrogen substitution was initiated. (I) 87 g (25 mol%) of 1,4-cyclohexanedicarboxylic acid (CHDA) (II) 190 g (50 mol%) of 6-hydroxy-2-naphthoic acid (HNA) (III) 4,4'-dihydroxybiphenyl 94g (25 mol%) (BP) Potassium acetate catalyst 45mg 214g acetic anhydride After the raw materials were charged, the polymerization vessel was purged with nitrogen and the temperature of the reaction system was raised to 200°C. The temperature was then raised further to the final polymerization temperature of 340°C over 6 hours, and the pressure was then reduced to 10 Torr (i.e., 1330 Pa) over 20 minutes, during which melt polymerization was carried out while distilling off acetic acid and other low-boiling components. After the stirring torque reached a predetermined value, nitrogen was introduced to change the pressure from reduced pressure to normal pressure and then to pressurized pressure, and the polymer was discharged from the bottom of the polymerization vessel and pelletized to obtain a pelletized resin.

[0061] <Examples 2 to 7 and Comparative Examples 1 to 4> Resins were obtained in the same manner as in Example 1, except that the types and charging ratios (mol%) of raw material monomers were as shown in Table 1 or Table 2. However, the final polymerization temperature was changed to 350°C in Example 4 and to 360°C in Comparative Examples 3 and 4. In the tables, APAP represents N-acetyl-p-aminophenol, TA represents 1,4-phenylenedicarboxylic acid, and HBA represents 4-hydroxybenzoic acid.

[0062] <Evaluation> The resins of the examples and comparative examples were evaluated for liquid crystallinity, melting point, and dielectric properties by the following methods. The results are shown in Table 1 or Table 2.

[0063] [Evaluation of liquid crystal properties] Using a polarizing microscope manufactured by Olympus Corporation, the resin was placed on a hot stage manufactured by Linkam Co., Ltd. and melted. The resin was observed under a nitrogen atmosphere at a magnification of 150 times under crossed Nicols, and the liquid crystallinity was evaluated according to the following criteria. ◯ (Good): An optically anisotropic molten phase was formed in the molten resin. × (bad): No optically anisotropic molten phase was formed in the molten resin.

[0064] [Melt point measurement] Using a DSC (manufactured by PerkinElmer), the endothermic peak temperature (Tm1) observed when the resin was heated from room temperature at a temperature increase rate of 20°C / min was measured, and the resin was then held at a temperature of (Tm1+40)°C for 2 minutes, and then cooled to room temperature at a temperature decrease rate of 20°C / min. The resin was then heated again at a temperature increase rate of 20°C / min, and the endothermic peak temperature observed was measured and used as the melting point of the resin.

[0065] [Evaluation of dielectric properties] The resin was molded using a molding machine ("SE-100DU" manufactured by Sumitomo Heavy Industries, Ltd.) under the following molding conditions to prepare a flat test piece measuring 80 mm × 80 mm × 1 mm. As shown in Figure 1, a test piece measuring 80 mm × 1 mm × 1 mm was cut from the center of the flat test piece in the flow direction and used as a test piece for evaluating dielectric properties. The relative permittivity and dielectric loss tangent of this test piece were measured at a measurement frequency of 5 GHz using a cavity resonator perturbation method complex permittivity evaluation device manufactured by Kanto Electronics Application Development Co., Ltd., with the following configuration. Scalar Network Analyzer: Agilent Technologies 8757D Frequency synthesizer: Agilent Technologies 83650L Sweep CW Generator Fixed attenuator: Agilent Technologies 85025D detector Cavity resonator: Kanto Electronics Application Development CP431 Measurement program: Kanto Electronics Application Development CPMA-S2 / V2 [Molding conditions] Cylinder temperature: 350°C (Examples 1 to 7 and Comparative Examples 1 and 2) 370°C (Comparative Example 3) Mold temperature: 80℃ Injection speed: 33mm / sec Holding pressure: 60MPa

[0066] [Table 1]

[0067] [Table 2] *In Comparative Example 4, although the polymerization reaction itself proceeded, viscosity increased during the polymerization process, and a normal sample could not be obtained, so no evaluation could be performed.

[0068] As is clear from the results shown in Table 1 or Table 2, it was confirmed that the liquid crystal resins of the examples had a low dielectric constant and a low dielectric loss tangent while maintaining a high melting point.

Claims

1. A liquid crystalline resin that exhibits optical anisotropy when melted, The liquid crystalline resin contains the following structural units (I), (II), and (III), and may or may not contain the following structural units (IV) and (V), the content of the structural unit (I) is 2.5 to 35 mol % based on all structural units; The content of the structural unit (II) is 25 to 55 mol% based on all structural units, The content of the structural unit (III) is 15 to 37.5% of all structural units, The content of the structural unit (IV) is 0 to 35 mol % based on all structural units, The content of the structural unit (V) is 0 to 15 mol% based on all structural units. Liquid crystalline resin. 【Chemical 1】 (In the formula, Ar １ and Ar ２ each independently represents a phenylene group, a naphthylene group, or a biphenylylene group; X and Y each independently represent an oxygen atom or an imino group.

2. 2. The liquid crystalline resin according to claim 1, wherein the total content of the structural units (I) to (V) is 100 mol % based on all the structural units.

3. The liquid crystal resin according to claim 1 or 2, wherein the structural unit (I) is a structural unit derived from one or more selected from the group consisting of 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, and derivatives thereof.

4. A liquid crystal resin composition comprising the liquid crystal resin according to claim 1 or 2.

5. A molded article made of the liquid crystalline resin according to claim 1 or 2.

6. A molded article made of the liquid crystalline resin composition according to claim 4.

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