Fully aromatic polyester, resin composition, molded article and method for manufacturing fully aromatic polyester

Abstract

A liquid crystal-like fully aromatic polyester with a lower flow start temperature than previously available is provided. It is a fully aromatic polyester exhibiting optical anisotropy upon melting, comprising the following constituent units (I), (II), (III), and (IV) as essential components: Constituent unit (I) comprises 17.5–26 mol% of all constituent units; Constituent unit (II) comprises 24–32.5 mol% of all constituent units; Constituent unit (III) comprises 17.5–26 mol% of all constituent units; Constituent unit (IV) comprises 24–32.5 mol% of all constituent units; The total content of constituent units (I), (II), (III), and (IV) is 100 mol%.

Description

Technical Field

[0001] This invention relates to a fully aromatic polyester exhibiting optical anisotropy upon melting, a resin composition, a molded article, and a method for manufacturing a fully aromatic polyester. Prior Technology

[0002] Liquid crystal resins such as fully aromatic polyesters have a good balance of excellent flowability, mechanical strength, heat resistance, chemical resistance and electrical properties, and are therefore widely used in various fields as high-performance engineering plastics. As fully aromatic polyesters, most commercially available ones are mainly composed of aromatic hydroxycarboxylic acids such as 4-hydroxybenzoic acid. However, the molding and processing temperature of liquid crystal resins with aromatic hydroxycarboxylic acids as the main component is a high temperature exceeding 350°C, which is too high for melt processing in general equipment. Patent Document 1 describes an aromatic polyester characterized by: not using p-hydroxybenzoic acid, but containing each constituent unit represented by a predetermined general formula in a predetermined amount.

[0003] Patent Document 1: Japanese Patent Application Publication No. 5-117374 Summary of the Invention

[0004] The objective of this invention is to provide a liquid crystal fully aromatic polyester with a lower flow start temperature than previously possible.

[0005] The present invention has the following features. [1] A fully aromatic polyester exhibiting optical anisotropy upon melting, comprising the following constituent units (I), (II), (III) and (IV) as essential components: The content of constituent unit (I) relative to all constituent units is 17.5~26 mol%. The content of constituent unit (II) relative to all constituent units is 24-32.5 mol%. The content of constituent unit (III) relative to all constituent units is 17.5-26 mol%. The content of constituent unit (IV) relative to all constituent units is 24-32.5 mol%. The total content of constituent units (I), (II), (III) and (IV) relative to all constituent units is 100 mol. [2] As described in [1], the flow start temperature of the fully aromatic polyester is below 310°C. [3] A resin composition comprising a fully aromatic polyester as described in [1] or [2]. [4] A molded article containing a fully aromatic polyester as described in [1] or [2]. [5] A method for manufacturing a fully aromatic polyester, which is a method for manufacturing a fully aromatic polyester that exhibits optical anisotropy during melting, comprising: After 4,4'-dihydroxybiphenyl and 1,4-dihydroxybenzene were acetylated with fatty acid anhydrides, they were then polycondensed with 1,4-epenylphenyl dicarboxylic acid and 2,6-naphthalenediic acid. Compared to all monomers containing 1,4-phenyl dicarboxylic acid, 2,6-naphthyl dicarboxylic acid, 4,4'-dihydroxybiphenyl, and 1,4-dihydroxybenzene, The amount of 1,4-epenylphenyldicarboxylic acid used is 17.5~26 mol%. The amount of 2,6-naphthalenedicarboxylic acid used is 24~32.5 moles; The amount of 4,4'-dihydroxybiphenyl used is 17.5~26 moles; The amount of 1,4-dihydroxybenzene used is 24~32.5 mol%. The total amount of 1,4-epoxyphenyl dicarboxylic acid, 2,6-naphthalenedilic acid, 4,4'-dihydroxybiphenyl, and 1,4-dihydroxybenzene used is 100 moles. [6] The method described in [5], wherein the aforementioned fatty acid anhydride contains acetic anhydride.

[0006] This invention enables the provision of liquid crystal fully aromatic polyesters with lower flow start temperatures than previously possible. Simple Explanation of the Diagram

[0007] none. Implementation

[0008] The following is a detailed description of one embodiment of the present invention. The present invention is not limited to the following embodiment, and appropriate modifications can be made to implement it without affecting the effects of the invention. When a specific description of one embodiment also applies to another embodiment, that description may be omitted in another embodiment. In this disclosure, the expression "X~Y" for a numerical range means "X and below Y". Furthermore, when a complex upper and lower limit value is specified for a specific parameter, any of these upper and lower limit values ​​can be combined to form a suitable numerical range.

[0009] [Fully Aromatic Polyester] The fully aromatic polyester of this embodiment is a fully aromatic polyester that exhibits optical anisotropy when melted, and includes the following constituent units (I), (II), (III), and (IV) as essential components: The content of each constituent unit is within the predetermined range described later. The fully aromatic polyester exhibits optical anisotropy upon melting and has a low flow initiation temperature, enabling melt processing at lower temperatures than before. Furthermore, conventional fully aromatic polyesters with aromatic hydroxycarboxylic acids as the main component suffer from low toughness, hardness, and brittleness in molded products; however, the fully aromatic polyester of this embodiment also exhibits excellent toughness, making it difficult to break even when the molded product is deformed. Additionally, in this disclosure, the content (moles%) of each constituent unit can be calculated based on the monomer addition ratio during polymerization. Alternatively, the proportion (moles%) of each constituent unit can be calculated using the thermal decomposition gas chromatography-mass spectrometry method described in Polymer Degradation and Stability vol. 76 (2002), 85-94.

[0010] Constituent unit (I) is derived from 1,4-epylphenyldicarboxylic acid (hereinafter also referred to as "TA") and its polymerizable derivatives. Examples of polymerizable derivatives include alkyl esters (with approximately 1 to 4 carbon atoms) and halides of 1,4-epylphenyldicarboxylic acid. The fully aromatic polyester contains 17.5 to 26 mol% of constituent unit (I) relative to all constituent units. When the content of constituent unit (I) is less than 17.5 mol% or more than 26 mol%, the effect of reducing the flow start temperature is insufficient, and low-temperature processability easily becomes insufficient. From the viewpoint of balancing low-temperature processability and toughness, the content of constituent unit (I) relative to all constituent units is preferably 18 to 26 mol%, more preferably 19 to 25.5 mol%, and even more preferably 20 to 25 mol%.

[0011] Although Patent Document 1 is characterized by containing a specified amount of aromatic dicarboxylic acids and aromatic diols represented by a specified general formula, the only compositions capable of lowering the melting point Tm to below 310°C are those that use 1,4-epylphenyl dicarboxylic acid and 1,3-epylphenyl dicarboxylic acid as aromatic dicarboxylic acids, in addition to 2,6-naphthalenedicarboxylic acid. In this embodiment, even when aromatic hydroxycarboxylic acids are not used, and only 2,6-naphthalenedicarboxylic acid and 1,4-epylphenyl dicarboxylic acid are used as aromatic dicarboxylic acids, by satisfying the constituent units (I) to (IV) and ensuring that the content of each constituent unit is within a specified range, the resin flow start temperature can be lower than before.

[0012] Constituent unit (II) is derived from 2,6-naphthalenedicarboxylic acid (hereinafter also referred to as "NDA") and its polymerizable derivatives. Examples of polymerizable derivatives include alkyl esters (with approximately 1 to 4 carbon atoms) and halides of 2,6-naphthalenedicarboxylic acid. The fully aromatic polyester contains 24 to 32.5 mol% of constituent unit (II) relative to all constituent units. When the content of constituent unit (II) is less than 24 mol% or more than 32.5 mol%, at least one of low-temperature processability and toughness tends to become insufficient. From the viewpoint of balancing low-temperature processability and toughness, the content of constituent unit (II) relative to all constituent units is preferably 24.5 to 32 mol%, more preferably 24.5 to 31 mol%, and even more preferably 25 to 30 mol%.

[0013] Constituent unit (III) is derived from 4,4'-dihydroxybiphenyl (hereinafter also referred to as "BP") and its polymerizable derivatives. Examples of polymerizable derivatives include alkyl esters (approximately 1-4 carbon atoms) and halides of 4,4'-dihydroxybiphenyl. The fully aromatic polyester contains 17.5-26 mol% of constituent unit (III) relative to all constituent units. When the content of constituent unit (III) is less than 17.5 mol% or more than 26 mol%, at least one of low-temperature processability and toughness tends to become insufficient. From the viewpoint of balancing low-temperature processability and toughness, the content of constituent unit (III) relative to all constituent units is preferably 18-26 mol%, more preferably 19-25.5 mol%, and even more preferably 20-25 mol%.

[0014] The constituent unit (IV) is derived from 1,4-dihydroxybenzene (hereinafter also referred to as "HQ") and its polymerizable derivatives. Examples of polymerizable derivatives include alkyl esters (with approximately 1 to 4 carbon atoms) and halides of 1,4-dihydroxybenzene. The fully aromatic polyester contains 24 to 32.5 mol% of the constituent unit (IV) relative to all constituent units. When the content of the constituent unit (IV) is less than 24 mol% or more than 32.5 mol%, at least one of low-temperature processability and toughness tends to become insufficient. From the viewpoint of balancing low-temperature processability and toughness, the content of the constituent unit (IV) is preferably 24.5 to 32 mol%, more preferably 24.5 to 31 mol%, and even more preferably 25 to 30 mol%.

[0015] The fully aromatic polyester contains constituent units (I) to (IV) in total of 100 moles relative to all constituent units.

[0016] "Exhibiting optical anisotropy upon melting" refers to the fact that fully aromatic polyesters are liquid crystal polymers. By using fully aromatic polyesters as liquid crystal polymers, they can simultaneously possess low-temperature processability and toughness.

[0017] Optical anisotropy during melting can be confirmed using conventional polarization inspection methods with crossed polarizers. More specifically, melting anisotropy can be confirmed using a polarizing microscope manufactured by OLYMPUS, where the sample is melted and observed at 150x magnification under a nitrogen atmosphere on a hot stage manufactured by LINKAM. Liquid crystal polymers exhibit optical anisotropy, allowing light to pass through when inserted between crossed polarizers. If a sample exhibits optical anisotropy, polarized light will pass through, for example, even in a molten, stationary liquid state.

[0018] Since the viscosity of nematic liquid crystal polymers decreases significantly above the melting point, they generally exhibit liquid crystal properties at or above the melting point as an indicator of processability.

[0019] At a temperature 10-40°C higher than the melting point of the fully aromatic polyester and a shear rate of 1000 / s, the melt viscosity of the aforementioned fully aromatic polyester is preferably below 1000 Pa·s, more preferably 4-500 Pa·s, even more preferably 4-250 Pa·s, and particularly preferably 5-100 Pa·s. When the melt viscosity is within the above range, the aforementioned fully aromatic polyester itself or a composition containing the aforementioned fully aromatic polyester can easily ensure flowability during molding, and the filling pressure is less likely to become excessive. Furthermore, in this disclosure, melt viscosity refers to the melt viscosity measured according to ISO 11443.

[0020] The flow initiation temperature of the fully aromatic polyester is preferably below 310°C, more preferably below 300°C, and even more preferably below 295°C. By setting the flow initiation temperature to below 310°C, a liquid crystal fully aromatic polyester with excellent melt processability at low temperatures can be obtained. In one embodiment, the flow initiation temperature of the fully aromatic polyester can be below 292°C. In another embodiment, the flow initiation temperature of the fully aromatic polyester can also be below 290°C or below 280°C.

[0021] The flow onset temperature is the temperature at which a fully aromatic polyester exhibits fluidity due to external force during heating, and it can be determined by the following method. Specifically, the flow onset temperature is determined as follows: using a capillary rheometer (e.g., a Shimadzu CFT-500 flow tester), when a sample of molten resin heated at a rate of 4°C / min is extruded from a nozzle with an inner diameter of 1 mm and a length of 10 mm under a weight of 100 kg / cm², the melt viscosity is 48,000 poise (°C).

[0022] [Manufacturing method of fully aromatic polyester] The method for manufacturing a fully aromatic polyester according to this embodiment is a method for manufacturing a fully aromatic polyester that exhibits optical anisotropy upon melting, comprising: pyrating 4,4'-dihydroxybiphenyl and 1,4-dihydroxybenzene with fatty acid anhydrides, followed by polycondensation with 1,4-epenylphenyldicarboxylic acid and 2,6-naphthalenedicarboxylic acid. 1,4-epenylphenyldicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 4,4'-dihydroxybiphenyl, and 1,4-dihydroxybenzene may each contain polymerizable derivatives thereof. Examples of polymerizable derivatives include alkyl esters (with approximately 1 to 4 carbon atoms), halides, etc.

[0023] (Vacation) Fatty acid anhydrides function as amides. Examples of fatty acid anhydrides include acetic anhydride, propionic anhydride, butyric anhydride, isobutyric anhydride, valeric anhydride, neovaleric anhydride, 2-ethylhexanoic anhydride, monochloroacetic anhydride, dichloroacetic anhydride, trichloroacetic anhydride, monobromoacetic anhydride, dibromoacetic anhydride, tribromoacetic anhydride, monofluoroacetic anhydride, difluoroacetic anhydride, trifluoroacetic anhydride, glutaric anhydride, maleic anhydride, succinic anhydride, and β-bromopropionic anhydride. It is preferable to use one or more of these fatty acid anhydrides.

[0024] From the perspective of price and operability, preferred fatty acid anhydrides include carboxylic anhydrides such as acetic anhydride, propionic anhydride, butyric anhydride, and isobutyric anhydride, and it is preferable to use one or more of them. Among these, considering ease of acquisition, fatty acid anhydrides preferably contain acetic anhydride.

[0025] From the viewpoint of ease of reaction control, the amount of fatty acid anhydride used is preferably 1.0 to 1.1 equivalents, more preferably 1.01 to 1.05 equivalents, relative to the total amount of hydroxyl groups in 4,4'-dihydroxybiphenyl and 1,4-dihydroxybenzene.

[0026] Compared to all monomers containing 1,4-epoxyphenyl dicarboxylic acid, 2,6-naphthodicarboxylic acid, 4,4'-dihydroxybiphenyl and 1,4-dihydroxybenzene, the amount of 4,4'-dihydroxybiphenyl used is 17.5 to 26 mol%, preferably 18 to 26 mol%, more preferably 19 to 25.5 mol%, and even more preferably 20 to 25 mol.

[0027] The amount of 1,4-dihydroxybenzene used is 24 to 32.5 mol%, more preferably 24.5 to 32 mol%, even more preferably 24.5 to 31 mol%, and still more preferably 25 to 30 mol%, relative to all monomers containing 1,4-phenyl dicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 4,4'-dihydroxybiphenyl and 1,4-dihydroxybenzene.

[0028] The acetylation can be carried out using known methods. For example, 4,4'-dihydroxybiphenyl and 1,4-dihydroxybenzene can be mixed with fatty acid anhydrides and heated at a temperature range of 120-160°C for about 0.5-5 hours to acetylate the mixture and obtain a reaction product containing the acetylated compound.

[0029] (Condensation polymerization) Next, the acetylated compound obtained by the above acetylation is polycondensed with 1,4-epenylphenyl dicarboxylic acid and 2,6-naphthalenedilic acid.

[0030] The amount of 1,4-phenyldicarboxylic acid used is 17.5 to 26 mol%, more preferably 18 to 26 mol%, more preferably 19 to 25.5 mol%, and even more preferably 20 to 25 mol%, relative to all monomers containing 1,4-phenyldicarboxylic acid, 2,6-naphthodicarboxylic acid, 4,4'-dihydroxybiphenyl and 1,4-dihydroxybenzene.

[0031] The amount of 2,6-naphthodicarboxylic acid used is 24 to 32.5 mol%, more preferably 24.5 to 32 mol%, even more preferably 24.5 to 31 mol%, and still more preferably 25 to 30 mol%, relative to all monomers containing 1,4-phenyl dicarboxylic acid, 2,6-naphthodicarboxylic acid, 4,4'-dihydroxybiphenyl and 1,4-dihydroxybenzene.

[0032] Polycondensation can be carried out using known methods. For example, acetylated compounds of 4,4'-dihydroxybiphenyl and 1,4-dihydroxybenzene are mixed with 1,4-epenylphenyl dicarboxylic acid and 2,6-naphthalene dicarboxylic acid and heated at a temperature range of 200-400°C for about 2-12 hours to achieve polycondensation.

[0033] In the method for manufacturing the fully aromatic polyester of this embodiment, the total amount of 1,4-epoxyphenyl dicarboxylic acid, 2,6-naphthalenediic acid, 4,4'-dihydroxybiphenyl and 1,4-dihydroxybenzene used is 100 moles.

[0034] During polycondensation reactions, melt polymerization, solution polymerization, slurry polymerization, solid-state polymerization, or a combination of two or more thereof can be used, with melt polymerization or a combination of melt polymerization and solid-state polymerization being preferred.

[0035] The fully aromatic polyester produced by the above-mentioned polycondensation reaction can be further polymerized by heating in an inert gas under normal or reduced pressure to increase its molecular weight. Solid-state polymerization can be carried out using methods already known. For example, it can be performed under reduced pressure or vacuum, in an inert gas stream such as nitrogen, at a temperature 10 to 120°C lower than the liquid crystal formation temperature of the raw material resin (a fully aromatic polyester obtained through polycondensation). Furthermore, since the melting point of the fully aromatic polyester increases as solid-state polymerization proceeds, solid-state polymerization can also be carried out above the original melting point of the raw material resin. Solid-state polymerization can be carried out at a fixed temperature or at high temperatures in stages. There are no particular limitations on the heating method; microwave heating, heaters, etc., can be used.

[0036] In carrying out the above reactions, known catalysts can be used. Representative catalysts 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), as well as organic compound catalysts such as 1-methylimidazole and 4-dimethylaminopyridine. Preferably, the catalyst includes one or more of these. The same catalyst can be used in acetylation reactions, condensation reactions (and solid-state polymerization reactions if necessary).

[0037] The above reactions can be initiated by placing all the starting monomers (4,4'-dihydroxybiphenyl, 1,4-dihydroxybenzene, 1,4-epylphenyldicarboxylic acid and 2,6-naphthalenedicarboxylic acid), fatty acid anhydrides and catalysts into the same reaction vessel (one-stage reaction). Alternatively, 4,4'-dihydroxybiphenyl and 1,4-dihydroxybenzene can be ylated with fatty acid anhydrides and then reacted separately with the carboxylic acid groups of 1,4-epylphenyldicarboxylic acid and 2,6-naphthalenedicarboxylic acid (two-stage reaction).

[0038] [Resin Composition] The resin composition of this embodiment contains the aforementioned fully aromatic polyester. Because it contains the aforementioned fully aromatic polyester, the flow initiation temperature is lower than conventionally, allowing for melt processing at a lower temperature than before. In one embodiment, the thermoplastic resin contained in the resin composition preferably comprises at least 80% by mass, and more preferably at least 90% by mass, of a fully aromatic polyester. In one embodiment, the thermoplastic resin contained in the resin composition may consist solely of the aforementioned fully aromatic polyester.

[0039] Resin compositions can be formulated with various fibrous, granular, and plate-like inorganic and organic fillers, depending on the intended use. Examples of fibrous inorganic fillers include glass fibers, ground glass fibers, carbon fibers, asbestos fibers, silica fibers, silica-alumina fibers, alumina fibers, zirconium oxide fibers, boron nitride fibers, silica nitride fibers, boron fibers, potassium titanate fibers, silicate fibers such as wollastonite, magnesium sulfate fibers, aluminum borate fibers, and fibrous materials of metals such as stainless steel, aluminum, titanium, copper, and brass. Glass fibers are a particularly representative fibrous filler. Examples of fibrous organic fillers include high-melting-point organic fibrous materials such as polyamide, fluoropolymers, polyester resins, and acrylic resins.

[0040] Examples of granular inorganic fillers include silicates of carbon black, graphite, silicon dioxide, quartz powder, glass beads, glass spheres, glass powder, kaolin, clay, diatomite, and wollastonite; oxides of metals such as iron oxide, titanium oxide, zinc oxide, antimony trioxide, and aluminum oxide; carbonates of metals such as calcium carbonate and magnesium carbonate; sulfates of metals such as calcium sulfate and barium sulfate; other ferrites; silicon carbide; silicon nitride; boron nitride; and various metal powders. Examples of plate-shaped inorganic fillers include mica, glass flakes, talc, and various metal foils.

[0041] The filler content is preferably 5 to 150 parts by weight, and more preferably 20 to 80 parts by weight, relative to 100 parts by weight of fully aromatic polyester. Before using the above-mentioned fillers, astringents or surface treatment agents may be used as needed.

[0042] Without impairing the effects of the present invention, the resin composition may also contain other components. Examples of other components include other thermoplastic resins, antioxidants, stabilizers, pigments, nucleating agents, and other additives.

[0043] There are no particular limitations on the manufacturing method of the resin composition; it can be prepared using conventionally known methods. For example, the resin composition can be prepared by melt-blending the components using a one-shaft or two-shaft extruder.

[0044] The flow initiation temperature of the resin composition is preferably below 310°C, more preferably below 300°C, and even more preferably below 295°C. In one embodiment, the flow initiation temperature of the resin composition can be below 292°C. In another embodiment, the flow initiation temperature of the resin composition can also be below 290°C or 280°C. Resin compositions with a flow initiation temperature of 310°C or below can be melt-processed at lower temperatures than previously possible.

[0045] [Molded product] The molded article of this embodiment is a molded article made using the above-described fully aromatic polyester or the above-described resin composition, including the above-described fully aromatic polyester. Because it contains the above-described fully aromatic polyester, it has excellent toughness and is not easily damaged even when deformed.

[0046] There are no particular limitations on the manufacturing method of the molded article; any 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, gas injection molding, and inflation molding.

[0047] The molded article of this embodiment has excellent formability, so it can be easily processed into various three-dimensional molded articles, fibers, films, etc. Examples of preferred applications include connectors, CPU sockets, relay switch components, bobbins, actuators, noise reduction filter cases, heating and fixing rollers for electronic circuit boards or OA machines, etc.

[0048] [Example] The following embodiments illustrate the invention in more detail, but the interpretation of the invention is not limited to these embodiments.

[0049] [Example 1] In a polymerization vessel equipped with a mixer, reflux column, monomer inlet, nitrogen inlet, and pressure reduction / outlet pipeline, add the following raw material monomers, fatty acid metal salt catalyst, and fatty acid anhydride to begin nitrogen replacement. (I) 1,4-Phenyldicarboxylic acid (TA) 0.5 mol (25 mol%) (II) 2,6-Naphthalenedicarboxylic acid (NDA) 0.5 mol (25 mol%) (III) 4,4'-Dihydroxybiphenyl (BP) 0.5 mol (25 mol%) (IV) 1,4-Dihydroxybenzene (HQ) 0.5 mol (25 mol%) Potassium acetate catalyst 150ppm Acetic anhydride 2.08 moles (1.04 equivalents of the total hydroxyl groups in BP and HQ)

[0050] After adding the raw materials, the temperature of the reaction system was raised to 140°C, and the reaction was carried out at 140°C for 3 hours (acetylation step). Then, the temperature was raised to 360°C over 4.5 hours, followed by a 15-minute decompression to 10 Torr (1330 Pa), during which acetic acid, excess acetic anhydride, and other low-boiling components were distilled off while polycondensation was carried out (polycondensation reaction step). Once the stirring torque reached the specified value, nitrogen gas was introduced, and the pressure was increased from reduced pressure to pressurized pressure, with the polymer discharged from the bottom of the polymerization vessel. The strand was then granulated to obtain fully aromatic polyester granules.

[0051] [Examples 2-4, Comparative Examples 3-5] Except that the raw material monomers and their proportions are set as described in Table 1, the fully aromatic polyester particles were obtained using the same method as in Example 1.

[0052] [Comparative Example 1] In a polymerization vessel equipped with a mixer, reflux column, monomer inlet, nitrogen inlet, and pressure reduction / outlet pipeline, add the following raw material monomers, fatty acid metal salt catalyst, and fatty acid anhydride to begin nitrogen replacement. (I) 1,4-Phenyldicarboxylic acid (TA) 0.46 mol (25 mol%) (III) 4,4'-Dihydroxybiphenyl (BP) 0.46 mol (25 mol%) 4-Hydroxybenzoic acid (HBA) 0.037 mol (2 mol%) 6-Hydroxy-2-naphthoic acid (HNA) 0.883 mol (48 mol%) Potassium acetate catalyst 150ppm Acetic anhydride 1.914 moles (1.04 equivalents relative to the total hydroxyl groups of BP, HBA, and HNA)

[0053] After adding the raw materials, the temperature of the reaction system was raised to 140°C, and the reaction was carried out at 140°C for 3 hours (acetylation step). Then, the temperature was raised to 360°C over 4.5 hours, followed by a 15-minute decompression to 10 Torr (i.e., 1330 Pa), during which acetic acid, excess acetic anhydride, and other low-boiling components were distilled off while polycondensation was carried out (polycondensation reaction step). Once the stirring torque reached the specified value, nitrogen gas was introduced, and the pressure was increased from reduced pressure to pressurized pressure, with the polymer discharged from the bottom of the polymerization vessel. The polymer was then granulated to obtain fully aromatic polyester granules.

[0054] [Comparative Example 2] In a polymerization vessel equipped with a mixer, reflux column, monomer inlet, nitrogen inlet, and pressure reduction / outlet pipeline, add the following raw material monomers, fatty acid metal salt catalyst, and fatty acid anhydride to begin nitrogen replacement. (I) 1,4-Phenyldicarboxylic acid (TA) 0.8 mol (40 mol%) (III) 4,4'-Dihydroxybiphenyl (BP) 0.4 mol (20 mol%) (IV) 1,4-Dihydroxybenzene (HQ) 0.4 mol (20 mol%) 6-Hydroxy-2-naphthoic acid (HNA) 0.4 mol (20 mol%) Potassium acetate catalyst 150ppm Acetic anhydride 2.08 moles (relative to 1.04 equivalents of the total hydroxyl groups in BP, HQ, and HNA)

[0055] After adding the raw materials, the temperature of the reaction system was raised to 140°C, and the reaction was carried out at 140°C for 3 hours (acetylation step). Then, the temperature was raised to 380°C over 4.5 hours, followed by a 15-minute depressurization to 10 Torr (i.e., 1330 Pa), during which acetic acid, excess acetic anhydride, and other low-boiling components were distilled off while polycondensation was carried out (polycondensation reaction step). After the stirring torque reached the specified value, nitrogen gas was introduced, and the pressure was increased from reduced pressure to pressurized pressure, with the polymer discharged from the bottom of the polymerization vessel. The polymer was then granulated to obtain fully aromatic polyester granules.

[0056] [Comparative Example 6] (I) 1,4-Phenyldicarboxylic acid (TA) 0.28 mol (14 mol%) (III) 4,4'-Dihydroxybiphenyl (BP) 0.4 mol (20 mol%) 1,3-Phenyldicarboxylic acid (IA) 0.12 mol (6 mol%) 4-Hydroxybenzoic acid (HBA) 1.2 moles (60 moles%) Potassium acetate catalyst 150ppm Acetic anhydride 2.08 moles (relative to the total hydroxyl content of BP and HBA 1.04 equivalents)

[0057] After adding the raw materials, the temperature of the reaction system was raised to 140°C, and the reaction was carried out at 140°C for 3 hours (acetylation step). Then, the temperature was raised to 360°C over 4.5 hours, followed by a depressurization to 10 Torr (1330 Pa) over 15 minutes, during which acetic acid, excess acetic anhydride, and other low-boiling components were distilled off while polycondensation was carried out (polycondensation reaction step). After the stirring torque reached the specified value, nitrogen gas was introduced, and the pressure was increased from reduced pressure to pressurized pressure, with the polymer discharged from the bottom of the polymerization vessel. The polymer was then granulated to obtain fully aromatic polyester granules.

[0058] (liquid crystalline) Using a polarizing microscope manufactured by OLYMPUS Inc., the fully aromatic polyesters obtained in the examples and comparative examples were melted on a LINKAM heating stage and observed under a nitrogen atmosphere at 150x magnification using a crossed nicol. Those forming optically anisotropic molten phases are indicated by "Y" in Table 1.

[0059] (Flow start temperature) Using a capillary rheometer (Shimadzu Corporation CFT-500 flow tester), the fully aromatic polyesters obtained in the examples and comparative examples were heated at a heating rate of 4°C / min. Under a weight of 9.8 MPa (100 kg / cm²), the melt viscosity was measured at the temperature at which it reached 4800 Pa·s (48000 poise) when extruded from a nozzle with an inner diameter of 1 mm and a length of 10 mm. The results are shown in Table 1.

[0060] (Bending test) Using a molding machine (Sumitomo Heavy Industries, Ltd. "SE30DUZ"), the fully aromatic polyester granules obtained in the Examples and Comparative Examples were molded under the following molding conditions to produce bending test pieces of 50mm × 4mm × 0.3mm. Using these test pieces, the bending strain at which the bending stress reached its maximum was measured under the following test conditions. The results are shown in Table 1. [Forming conditions] Cylinder temperature: Examples 1-4, Comparative Example 6: 350℃ Examples 1, 3~5: 370℃ Comparative Example 2: 380℃ Metal mold temperature: 90℃ Ejection velocity: 33mm / sec Pressure holding: 50MPa [Experimental Conditions] Test speed: 2.0 mm / min Distance between pivots: 4.8mm Indenter radius: 0.5mm Support platform radius: 0.5mm Elastic modulus: secant method

[0061] [Table 1] Example Example Example Example Comparative example Comparative example Comparative example Comparative example Comparative example Comparative example 1 2 3 4 1 2 3 4 5 6 Monomer composition Aromatic Dicarboxylic acid TA Moer% 25 20 25 20 25 40 27.5 15 25 14 NDA Moer% 25 30 25 30 22.5 35 25 IA Moer% 6 Aromatic Diol BP Moer% 25 20 20 25 25 20 25 20 15 20 HQ Moer% 25 30 30 25 20 25 30 35 Aromatic Hydroxycarboxylic acid HBA Moer% 2 60 HNA Moer% 48 20 total Moer% 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 Liquid crystallinity - Y Y Y Y Y Y Y Y Y Y Flow start temperature ℃ 283 282 274 292 329 372 322 326 312 316 Bending strain % 11.3 11.5 10.8 10.9 6.5 6.5 10.9 10.3 10.1 8.3

[0062] As shown in Table 1, the fully aromatic polyesters of Examples 1-4 do not use aromatic hydroxycarboxylic acids, but are composed only of aromatic dicarboxylic acids and aromatic diols. These fully aromatic polyesters have a flow initiation temperature of below 310°C, which is lower than previously observed, thus exhibiting excellent melt processability at low temperatures. Furthermore, since the resulting molded articles have a flexural strain of over 9%, they are not easily damaged even when deformed. In contrast, the flow initiation temperature of the fully aromatic polyesters in Comparative Examples 1-6 all exceeded 310°C, requiring high-temperature melt processing. Furthermore, the molded articles obtained from the fully aromatic polyesters in Comparative Examples 1, 2, and 6 had a flexural strain of less than 9%, making them easily damaged during deformation. [Industry availability]

[0063] The flow initiation temperature of the fully aromatic polyester in this embodiment is lower than that of the past, thus making it industrially viable as a high-performance engineering plastic with excellent melt processability at low temperatures.

[0064] none

Claims

1. A fully aromatic polyester exhibiting optical anisotropy upon melting, comprising the following constituent units (I), (II), (III) and (IV) as essential components: , wherein the content of constituent unit (I) is 17.5 to 26 mol% relative to all constituent units; the content of constituent unit (II) is 24 to 32.5 mol% relative to all constituent units; the content of constituent unit (III) is 17.5 to 26 mol% relative to all constituent units; the content of constituent unit (IV) is 24 to 32.5 mol% relative to all constituent units; and the total content of constituent units (I), (II), (III) and (IV) is 100 mol relative to all constituent units.

2. The fully aromatic polyester described in Request 1 has a flow start temperature of 310°C or below.

3. A resin composition comprising a fully aromatic polyester as described in claim 1 or 2.

4. A molded article containing a fully aromatic polyester as described in claim 1 or 2.

5. A method for manufacturing a fully aromatic polyester, specifically a fully aromatic polyester exhibiting optical anisotropy upon melting, comprising: pyrating 4,4'-dihydroxybiphenyl and 1,4-dihydroxybenzene with fatty acid anhydrides, followed by polycondensation with 1,4-epoxyphenyldicarboxylic acid and 2,6-naphthalenedicarboxylic acid, wherein, relative to all monomers comprising 1,4-epoxyphenyldicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 4,4'-dihydroxybiphenyl, and 1,4-dihydroxybenzene, the amount of 1,4-epoxyphenyldicarboxylic acid used is 17.5~26 mol%; the amount of 2,6-naphthalenedicarboxylic acid used is 24~32.5 mol%; the amount of 4,4'-dihydroxybiphenyl used is 17.5~26 mol%; and the amount of 1,4-dihydroxybenzene used is 24~32.5 mol%. The total amount of 1,4-epoxyphenyl dicarboxylic acid, 2,6-naphthalenedilic acid, 4,4'-dihydroxybiphenyl, and 1,4-dihydroxybenzene used is 100 moles.

6. The method as described in claim 5, wherein, The aforementioned fatty acid anhydrides include acetic anhydride.

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