TWI887233B - Wholly aromatic polyester and polyester resin composition - Google Patents

Abstract

[Problem] Provided are a wholly aromatic polyester with an extremely small amount of side reactions during polymerization and with excellent color phase and a polyester resin composition containing said wholly aromatic polyester. [Solution] The abovementioned problem is solved with a wholly aromatic polyester characterized by comprising the following structural units (I), (II), (III), and (IV) as essential components, wherein: the content of structural unit (I) with respect to all structural units is 40-75 mol%; the content of structural unit (II) with respect to all structural units is 0.5-7.5 mol%; the content of structural unit (III) with respect to all structural units is 8.5-30 mol%; the content of structural unit (IV) with respect to all structural units is 8.5-30 mol%; the total content of structural units (I), (II), (III), and (IV) with respect to all structural units is 100 mol%; the wholly aromatic polyester comprises ester bonds or a combination of ester bonds and ketone bonds in molecules thereof; and the amount of ketone bonds with respect to the total of ester bonds and ketone bonds is 0.0000-0.0010 mol%.

Description

Wholly aromatic polyester and polyester resin composition

The present invention relates to a wholly aromatic polyester having very little side reaction during polymerization and excellent hue and toughness, and a polyester resin composition thereof.

Liquid crystal resins such as wholly aromatic polyesters are widely used as high-performance engineering plastics because they have well-balanced excellent fluidity, mechanical strength, heat resistance, chemical resistance, electrical properties, etc.

As a fully aromatic polyester, most products currently on the market contain 4-hydroxybenzoic acid as the main component. However, the melting point of the homopolymer of 4-hydroxybenzoic acid becomes higher than the decomposition point, so it is necessary to copolymerize various components to lower the melting point.

The melting point of wholly aromatic polyesters using 1,4-phenylenedicarboxylic acid, 1,4-dihydroxybenzene, 4,4'-dihydroxybiphenyl, etc. as copolymer components is as high as 350°C or more, which is too high for melt processing using general-purpose equipment. In order to lower the melting point of such high-melting polyesters to a temperature that can be processed using general-purpose melt processing equipment, various methods have been tried, but there is a problem that when the melting point is lowered to a certain extent, the mechanical strength at high temperature (near the melting point) cannot be maintained.

In order to solve this problem, a wholly aromatic polyester has been proposed which is composed of a specific structure having 6-hydroxy-2-naphthoic acid as a main component (Patent Document 1). [Prior Art Document] [Patent Document]

[Patent Document 1] Japanese Patent Application Publication No. 2002-179776

[The problem that the invention is trying to solve]

However, the wholly aromatic polyester of Patent Document 1 has the following problems: ketone bonds are formed by side reactions during polymerization, the hue of the polymer is deteriorated by the products generated by the ketone bonds, and at the same time the toughness of the polymer is reduced.

The subject of the present invention is to provide a wholly aromatic polyester having very few side reactions during polymerization and excellent hue and toughness, and a polyester resin composition thereof. [Means for solving the subject]

The inventors of the present invention have found that the above-mentioned problems can be solved by a wholly aromatic polyester, and have thus completed the present invention. The wholly aromatic polyester is characterized in that it is a wholly aromatic polyester composed of the following constituent units (I), (II), (III) and (IV) as essential constituents, wherein the content of the constituent unit (I) is 40 to 75 mol % relative to all the constituent units, the content of the constituent unit (II) is 0.5 to 7.5 mol % relative to all the constituent units, and the content of the constituent unit (III) is 0.5 to 7.5 mol % relative to all the constituent units. The content of the constituent unit (III) is 8.5 to 30 mol% relative to all the constituent units, the content of the constituent unit (IV) is 8.5 to 30 mol% relative to all the constituent units, the total content of the constituent units (I), (II), (III) and (IV) is 100 mol% relative to all the constituent units, and there is an ester bond or a combination of an ester bond and a ketone bond in the molecule, and the amount of the ketone bond is 0.0000 to 0.0010 mol% relative to the total of the ester bond and the ketone bond. More specifically, the present invention provides the following. [Chemistry 1]

(1) A wholly aromatic polyester characterized in that it is a wholly aromatic polyester composed of the following constituent units (I), (II), (III) and (IV) as essential constituent components: the content of the constituent unit (I) is 40 to 75 mol% relative to all the constituent units; the content of the constituent unit (II) is 0.5 to 7.5 mol% relative to all the constituent units; the content of the constituent unit (III) is 8.5 to 30 mol% relative to all the constituent units; the content of the constituent unit (IV) is 8.5 to 30 mol% relative to all the constituent units; the total content of the constituent units (I), (II), (III) and (IV) is 100 mol% relative to all the constituent units. Furthermore, the molecule has an ester bond or a combination of an ester bond and a ketone bond, and the amount of the ketone bond is 0.0000 to 0.0010 mol% relative to the total of the ester bond and the ketone bond. [Chemistry 2] (2) A polyester resin composition comprising the wholly aromatic polyester described in (1). (3) A polyester molded article obtained by molding the wholly aromatic polyester or the polyester resin composition described in (1) or (2). (4) A method for producing a wholly aromatic polyester, which is a method for producing a wholly aromatic polyester, comprising: acylation of 6-hydroxy-2-naphthoic acid, 4-hydroxybenzoic acid, and 4,4'-dihydroxybiphenyl using fatty acid anhydride, and ester exchange with 1,4-phenylenedicarboxylic acid, wherein the amount of 6-hydroxy-2-naphthoic acid used is 40-75 mol%, the amount of 4-hydroxybenzoic acid used is 0.5-7.5 mol%, and the amount of 1,4-phenylenedicarboxylic acid used is 8.5-30 mol%, relative to the total monomers composed of 6-hydroxy-2-naphthoic acid, 4-hydroxybenzoic acid, 1,4-phenylenedicarboxylic acid, and 4,4'-dihydroxybiphenyl. The amount of 4,4'-dihydroxybiphenyl used is 8.5 to 30 mol%, the total amount of 6-hydroxy-2-naphthoic acid, 4-hydroxybenzoic acid, 1,4-phenylenedicarboxylic acid, and 4,4'-dihydroxybiphenyl used is 100 mol%, and the final polymerization temperature is 340°C or less. (5) The method for producing a wholly aromatic polyester as described in (4), characterized in that a nitrogen-containing heterocyclic compound is used as a catalyst. (6) The method for producing a wholly aromatic polyester as described in (5), wherein the nitrogen-containing heterocyclic compound is 1-methylimidazole. (7) The method for producing a wholly aromatic polyester as described in (4), characterized in that a potassium compound and/or a trivalent cobalt compound is used as a catalyst. (8) The method for producing a wholly aromatic polyester as described in (7), wherein the potassium compound is potassium acetate. (9) The method for producing a wholly aromatic polyester as described in (7) or (8), wherein the trivalent cobalt compound is tris(2,4-pentanedione)cobalt(III). [Effect of the Invention]

According to the present invention, a wholly aromatic polyester having a very small amount of side reactions during polymerization and excellent hue and toughness, and a polyester resin composition thereof can be provided.

[Form for implementing the invention]

Hereinafter, one embodiment of the present invention will be described in detail. The present invention is not limited to the following embodiments, and can be implemented with appropriate changes within the scope that does not hinder the effects of the present invention. In addition, in the present invention, the so-called "A to B" means "A or more and B or less".

[Wholly aromatic polyester] The wholly aromatic polyester of the present invention is a wholly aromatic polyester, characterized in that it is a wholly aromatic polyester composed of the following constituent units (I), (II), (III) and (IV) as essential constituent components, wherein the content of the constituent unit (I) is 40 to 75 mol % relative to all the constituent units, the content of the constituent unit (II) is 0.5 to 7.5 mol % relative to all the constituent units, and the content of the constituent unit (III) is 0.5 to 7.5 mol % relative to all the constituent units. ) is 8.5 to 30 mol% relative to all constituent units, the content of constituent unit (IV) is 8.5 to 30 mol% relative to all constituent units, the total content of constituent units (I), (II), (III) and (IV) is 100 mol% relative to all constituent units, and there is an ester bond or a combination of an ester bond and a ketone bond in the molecule, and the amount of the ketone bond is 0.0000 to 0.0010 mol% relative to the total of the ester bond and the ketone bond. [Chemistry 3]

Constituent unit (I) is derived from 6-hydroxy-2-naphthoic acid (hereinafter, also referred to as "HNA"). The wholly aromatic polyester of the present invention contains 40 to 75 mol% of constituent unit (I) relative to all constituent units. If the content of constituent unit (I) is less than 40 mol%, the melting point is lowered and the heat resistance is insufficient. If the content of constituent unit (I) is greater than 75 mol%, solidification occurs during polymerization and no polymer can be obtained. From the viewpoint of heat resistance and polymerizability, the content of constituent unit (I) is preferably 40 to 70 mol%, more preferably 40 to 65 mol%, further preferably 40 to 63 mol%, further preferably 40 to 62 mol%, and particularly preferably 40 to 60 mol%.

Constituent unit (II) is derived from 4-hydroxybenzoic acid (hereinafter, also referred to as "HBA"). The wholly aromatic polyester of the present invention contains 0.5 to 7.5 mol% of constituent unit (II) relative to all constituent units. If the content of constituent unit (II) is less than 0.5 mol%, solidification occurs during polymerization and no polymer can be obtained. If the content of constituent unit (II) is greater than 7.5 mol%, the melting point decreases and the heat resistance is insufficient. From the viewpoint of heat resistance and polymerizability, the content of constituent unit (II) is preferably 0.5 to 7.0 mol%, more preferably 1.0 to 7.0 mol%, more preferably 1.2 to 7.0 mol%, still more preferably 1.5 to 6.5 mol%, and particularly preferably 2.0 to 6.0 mol%.

The constituent unit (III) is derived from 1,4-phenylenedicarboxylic acid (hereinafter, also referred to as "TA"). The wholly aromatic polyester of the present invention contains 8.5 to 30 mol% of the constituent unit (III) relative to all the constituent units. If the content of the constituent unit (III) is less than 8.5 mol% or greater than 30 mol%, at least one of the low melting point and the heat resistance is likely to become insufficient. From the perspective of having both low melting point and heat resistance, the content of the constituent unit (III) is preferably 10 to 30 mol%, more preferably 12 to 28 mol%, further preferably 14 to 28 mol%, further preferably 15 to 28 mol%, and particularly preferably 17 to 27 mol%.

The constituent unit (IV) is derived from 4,4'-dihydroxybiphenyl (hereinafter, also referred to as "BP"). The wholly aromatic polyester of the present invention contains 8.5 to 30 mol% of the constituent unit (IV) relative to all the constituent units. If the content of the constituent unit (IV) is less than 8.5 mol% or greater than 30 mol%, at least one of the low melting point and heat resistance is likely to become insufficient. From the perspective of having both low melting point and heat resistance, the content of the constituent unit (IV) is preferably 10 to 30 mol%, more preferably 12 to 28 mol, further preferably 14 to 28 mol, further preferably 15 to 28 mol, and particularly preferably 17 to 27 mol.

As described above, the wholly aromatic polyester of the present invention contains a specific amount of specific structural units, i.e., (I) to (IV), relative to all structural units. Since the molecule has an ester bond or a combination of an ester bond and a ketone bond, and the amount of the ketone bond is 0.0000 to 0.0010 mol % relative to the total of the ester bond and the ketone bond, side reactions during polymerization are very few and the color is excellent. In the wholly aromatic polyester of the present invention, the amount of the ketone bond is preferably 0.0000 to 0.0008 mol, more preferably 0.0000 to 0.0006 mol, further preferably 0.0000 to 0.0005 mol, further preferably 0.0000 to 0.0004 mol, and particularly preferably 0.0000 to 0.0002 mol, relative to the total of the ester bond and the ketone bond. Furthermore, the wholly aromatic polyester of the present invention contains the constituent units (I) to (IV) in a total amount of 100 mol% relative to all constituent units.

Next, the properties of the wholly aromatic polyester are described. The wholly aromatic polyester of the present invention exhibits optical anisotropy when melted. The so-called exhibiting optical anisotropy when melted means that the wholly aromatic polyester of the present invention is a liquid crystalline polymer.

In the present invention, the so-called wholly aromatic polyester is a liquid crystalline polymer, which means that the wholly aromatic polyester has both thermal stability and easy processability, which are essential elements. The wholly aromatic polyester composed of the above-mentioned constituent units (I) to (IV) may not form an anisotropic melt phase depending on the constituent components and the sequence distribution in the polymer, but the polymer of the present invention is limited to wholly aromatic polyesters that show optical anisotropy when melted.

The properties of melt anisotropy can be confirmed by conventional polarization inspection methods 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 a magnification of 150 times in a nitrogen atmosphere. Liquid crystal polymers are optically anisotropic and allow light to pass through when inserted between crossed polarizers. If the sample is optically anisotropic, polarized light will pass through even if it is in a molten static liquid state, for example.

Nematic liquid crystal polymers have a significant decrease in viscosity above their melting point, so generally speaking, the fact that they show liquid crystallinity at or above the melting point is an indicator of processability. From the perspective of heat resistance, the melting point is preferably as high as possible, but if the thermal degradation of the polymer during melt processing and the heating capacity of the molding machine are taken into consideration, the preferred standard is 380°C or less. In addition, 260-370°C is more preferred, 270-370°C is more preferred, and 280-360°C is particularly preferred.

The melt viscosity of the aforementioned wholly aromatic polyester at a temperature 10 to 40°C higher than the melting point of the wholly aromatic polyester of the present invention and a shear rate of 1000/second is preferably 1000 Pa·s or less, more preferably 4 to 500 Pa·s, further preferably 4 to 250 Pa·s, and particularly preferably 5 to 100 Pa·s. If the above melt viscosity is within the above range, the aforementioned wholly aromatic polyester itself or the composition containing the aforementioned wholly aromatic polyester can easily ensure fluidity during its molding, and the filling pressure is not likely to become excessive. In addition, in this specification, the so-called melt viscosity refers to the melt viscosity measured in accordance with ISO11443.

Next, the production method of the wholly aromatic polyester of the present embodiment is described. The wholly aromatic polyester of the present embodiment is polymerized using a direct polymerization method or an ester exchange method. During the polymerization, a melt polymerization method, a solution polymerization method, a slurry polymerization method, a solid phase polymerization method, or a combination of two or more of these methods is used, and preferably a melt polymerization method or a combination of a melt polymerization method and a solid phase polymerization method is used.

In this embodiment, during polymerization, a monomer with activated terminal can be used as an acylation agent or an acyl chloride derivative for the polymerized monomer. Examples of the acylation agent include fatty acid anhydrides such as acetic anhydride.

In the method for producing wholly aromatic polyester of the present embodiment, from the viewpoint of hue, the amount of fatty acid anhydride used is preferably less than 1.08 times the total hydroxyl equivalent of 6-hydroxy-2-naphthoic acid, 4-hydroxybenzoic acid, and 4,4'-dihydroxybiphenyl, more preferably 1.00 to 1.07 times, further preferably 1.01 to 1.07 times, further preferably 1.01 to 1.06 times, and particularly preferably 1.02 to 1.06 times.

In such polymerization, various catalysts can be used. Representative examples include metal salt catalysts such as potassium acetate, magnesium acetate, tin (II) acetate, tetrabutyl titanium, lead acetate, sodium acetate, antimony trioxide, cobalt (III) tris(2,4-pentanedionato) and organic compound catalysts such as 1-methylimidazole and 4-dimethylaminopyridine.

The reaction may be initiated by charging all raw material monomers (6-hydroxy-2-naphthoic acid, 4-hydroxybenzoic acid, 1,4-phenylenedicarboxylic acid, and 4,4'-dihydroxybiphenyl), an acylation agent, and a catalyst into the same reaction vessel (a one-stage method), or by acylation of the hydroxyl groups of 6-hydroxy-2-naphthoic acid, 4-hydroxybenzoic acid, and 4,4'-dihydroxybiphenyl with an acylation agent and then reacting them with the carboxyl group of 1,4-phenylenedicarboxylic acid (a two-stage method).

Melt polymerization starts with decompression after the reaction system reaches a specified temperature, and continues until the specified decompression degree is reached. After the torque of the stirrer reaches a specified value, an inert gas is introduced, and the system is discharged from the decompression state to the specified pressurized state via normal pressure, and the wholly aromatic polyester is discharged from the reaction system.

The wholly aromatic polyester produced by the above polymerization method can be further increased in molecular weight by solid phase polymerization under normal pressure or reduced pressure in an inert gas.

The method for producing the wholly aromatic polyester of the present embodiment preferably comprises the steps of acylation of 6-hydroxy-2-naphthoic acid, 4-hydroxybenzoic acid, and 4,4'-dihydroxybiphenyl with fatty acid anhydride and ester exchange with 1,4-phenylenedicarboxylic acid. Relative to the total monomers composed of 6-hydroxy-2-naphthoic acid, 4-hydroxybenzoic acid, 1,4-phenylenedicarboxylic acid, and 4,4'-dihydroxybiphenyl, the amount of 6-hydroxy-2-naphthoic acid used is 40 to 75 mol%, which is higher than that of the total monomers composed of 6-hydroxy-2-naphthoic acid, 4-hydroxybenzoic acid, 1,4-phenylenedicarboxylic acid, and 4,4'-dihydroxybiphenyl. From the viewpoint of polymerizability, the preferred amount is 40 to 70 mol, more preferably 40 to 65 mol, still more preferably 40 to 63 mol, still more preferably 40 to 62 mol, and particularly preferably 40 to 60 mol. The amount of 4-hydroxybenzoic acid used is 0.5 to 7.5 mol. From the viewpoint of heat resistance and polymerizability, the preferred amount is 0.5 to 7.0 mol, more preferably 1.0 to 7.0 mol, still more preferably 1.2 to 7.0 mol, still more preferably 1.5 to 6.5 mol, and particularly preferably The amount of 1,4-phenylenedicarboxylic acid used is 2.0 to 6.0 mol%, and the amount of 1,4-phenylenedicarboxylic acid used is 8.5 to 30 mol. From the perspective of both low melting point and heat resistance, it is preferably 10 to 30 mol, more preferably 12 to 28 mol, more preferably 14 to 28 mol, more preferably 15 to 28 mol, and particularly preferably 17 to 27 mol. The amount of 4,4'-dihydroxybiphenyl used is 8.5 to 30 mol. From the perspective of both low melting point and heat resistance, it is preferably 10 to 30 mol. mol%, preferably 12-28 mol%, more preferably 14-28 mol%, more preferably 15-28 mol%, particularly preferably 17-27 mol%, The total amount of 6-hydroxy-2-naphthoic acid, 4-hydroxybenzoic acid, 1,4-phenylenedicarboxylic acid, and 4,4'-dihydroxybiphenyl is preferably 100 mol%, The final polymerization temperature is preferably below 340°C, more preferably below 330°C, more preferably below 320°C, still more preferably below 310°C, and particularly preferably below 300°C.

The method for producing wholly aromatic polyester of the present embodiment preferably uses a nitrogen-containing heterocyclic compound as a catalyst.

In the method for producing wholly aromatic polyester of the present embodiment, the nitrogen-containing heterocyclic compound used as a catalyst is preferably 1-methimidazole.

The method for producing wholly aromatic polyester of the present embodiment preferably uses a potassium compound and/or a trivalent cobalt compound as a catalyst.

In the method for producing wholly aromatic polyester of the present embodiment, the potassium compound used as a catalyst is preferably potassium acetate.

In the method for producing wholly aromatic polyester of the present embodiment, the trivalent cobalt compound used as a catalyst is preferably cobalt (III) bis(2,4-pentanedionato).

In the method for producing a wholly aromatic polyester of the present embodiment, from the viewpoint of increasing the molecular weight, it is preferred that the difference between the amount (mol %) of 1,4-phenylenedicarboxylic acid used and the amount (mol %) of 4,4'-dihydroxybiphenyl used is 1.00 mol % or less, more preferably 0.75 mol % or less, further preferably 0.50 mol % or less, and still further preferably 0.25 mol % or less. It is particularly preferred that the amount (mol %) of 1,4-phenylenedicarboxylic acid used is equal to the amount (mol %) of 4,4'-dihydroxybiphenyl used.

[Polyester resin composition] The wholly aromatic polyester of the present invention may be blended with various inorganic and organic fillers in the form of fibers, particles, or plates, depending on the intended use.

The inorganic filler mixed in the polyester resin composition of the present invention may be in the form of fiber, powder, or plate.

Examples of fibrous inorganic fillers include glass fiber, milled glass fiber, sponge fiber, silica fiber, silica/alumina fiber, alumina fiber, zirconia fiber, boron nitride fiber, silicon nitride fiber, boron fiber, potassium titanium fiber, fibers of silicates such as wollastonite, magnesium sulfate fiber, aluminum borate fiber, and inorganic fibrous materials such as stainless steel, aluminum, titanium, copper, and brass. A particularly representative fibrous filler is glass fiber.

In addition, examples of the powdery particulate inorganic filler include carbon black, graphite, silica, quartz powder, glass beads, hollow glass spheres, glass powder, silicates such as calcium silicate, aluminum silicate, kaolin, clay, diatomaceous earth, and wollastonite, metal oxides such as iron oxide, titanium oxide, zinc oxide, antimony trioxide, and aluminum oxide, metal carbonates such as calcium carbonate and magnesium carbonate, metal sulfates such as calcium sulfate and barium sulfate, other granular iron, silicon carbide, silicon nitride, boron nitride, and various metal powders.

Examples of plate-like inorganic fillers include mica, glass flakes, talc, and various metal foils.

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

These inorganic and organic fillers can be used alone or in combination of two or more. The combination of fibrous inorganic fillers and granular or plate-like inorganic fillers is preferably a combination that combines mechanical strength with dimensional accuracy, electrical properties, etc. It is particularly preferred that the fibrous filler is glass fiber and the plate-like filler is mica and talc, and the blending amount is less than 120 parts by mass relative to 100 parts by mass of the wholly aromatic polyester, preferably 20 to 80 parts by mass. By combining glass fiber with mica or talc, the thermal deformation temperature and mechanical properties of the polyester resin composition are particularly significantly improved.

When using such fillers, a sizing agent or surface treatment agent may be used if necessary.

The polyester resin composition of the present invention, as described above, contains the wholly aromatic polyester of the present invention as an essential component, and contains an inorganic or organic filler as needed, but may also contain other components as long as they do not impair the effects of the present invention. Here, the so-called other components may be any components, for example, other resins, antioxidants, stabilizers, pigments, crystallization nucleating agents and other additives.

The method for producing the polyester resin composition of the present invention is not particularly limited, and the polyester resin composition can be produced by a conventionally known method.

[Polyester molded product] The polyester molded product of the present invention can be obtained by molding the wholly aromatic polyester or polyester resin composition of the present invention. The molding method is not particularly limited, and a general molding method can be adopted. Examples of general molding methods include injection molding, extrusion molding, compression molding, blow molding, vacuum molding, foam molding, rotation molding, gas-assisted injection molding (gas injection molding), and inflation molding.

The polyester molded article obtained by molding the wholly aromatic polyester of the present invention has excellent heat resistance. In addition, the polyester molded article obtained by molding the polyester resin composition of the present invention has excellent heat resistance and contains an inorganic or organic filler as required, so that the mechanical strength is further improved.

Furthermore, the wholly aromatic polyester and polyester resin composition of the present invention can be processed into various three-dimensional molded products, fibers, films, etc. due to their excellent moldability.

Preferred uses of the polyester molded product of the present invention having the above-mentioned properties include connectors, CPU sockets, relay switch parts, bobbins, actuators, noise reduction filter boxes, electronic circuit boards, or heating and fixing rollers of OA equipment. [Example]

The present invention is described in more detail below by way of examples, but the present invention is not limited to these examples.

<Example 1> In a polymerization container equipped with a stirrer, a reflux column, a monomer inlet, a nitrogen inlet, and a decompression/outflow line, the following raw monomers, a fatty acid metal salt catalyst, and an acylation agent are loaded, and nitrogen substitution is started. (I) 6-Hydroxy-2-naphthoic acid 0.883 mol (48 mol%) (HNA) (II) 4-Hydroxybenzoic acid 0.037 mol (2 mol%) (HBA) (III) 1,4-phenylenedicarboxylic acid 0.46 mol (25 mol%) (TA) (IV) 4,4'-dihydroxybiphenyl 0.46 mol (25 mol%) (BP) 1-Methylimidazole catalyst 1100 ppm Acetic anhydride 1.91 mol (1.04 times the total hydroxyl equivalent of HNA, HBA, and BP) After loading the raw materials, the temperature of the reaction system was raised to 140°C and the reaction was allowed to proceed at 140°C for 1 hour. Thereafter, the temperature was further increased at the speed conditions shown in Table 1, and the final polymerization temperature was set as shown in Table 1, while acetic acid, excess acetic anhydride, and other low-boiling components were distilled out, and melt polymerization was performed. After the stirring torque reached the specified value, nitrogen was introduced to pressurize the reactor, and the product was discharged from the bottom of the polymerization vessel and crushed to obtain a powdered prepolymer. The obtained prepolymer was heat-treated (solid phase polymerization) at 230°C for 10 hours, 320°C for 30 hours, and 330°C for 30 hours under a nitrogen flow to obtain the target polymer.

<Evaluation> The melting point, melt viscosity, ketone bond content and hue (L value) of the wholly aromatic polyester of Example 1 were evaluated by the following method. The evaluation results are shown in Table 1.

[Melting point] The endothermic peak temperature (Tm1) observed when the wholly aromatic polyester was heated from room temperature at a rate of 20°C/min was measured using a differential scanning calorimeter (DSC, manufactured by Perkin Elmer). After the temperature was maintained at (Tm1+40)°C for 2 minutes, the mixture was temporarily cooled to room temperature at a rate of 20°C/min, and the endothermic peak temperature observed when the mixture was heated at a rate of 20°C/min was measured again.

[Melt viscosity] The melt viscosity of wholly aromatic polyester was measured using a capillography manufactured by Toyo Seiki Seisaku-sho, Ltd., at a temperature 10 to 30°C higher than the melting point of wholly aromatic polyester, using an orifice with an inner diameter of 0.5 mm and a length of 30 mm, at a shear rate of 1000/sec and in compliance with ISO11443.

[Ketone bond amount] The ketone bond amount was calculated by the thermal decomposition gas chromatography method described in Polymer Degradation and Stability 76 (2002) 85-94. Specifically, a wholly aromatic polyester was heated in the presence of tetramethylammonium hydroxide (TMAH) using a thermal decomposition device ("PY2020iD" manufactured by Frontier Laboratories Co., Ltd.), and a gas was generated by thermal decomposition/methylation. This gas was analyzed by gas chromatography ("GC-6890N" manufactured by Agilent Technologies Co., Ltd.), and the ketone bond amount was calculated from the ratio of the peak area derived from the ketone bond to the peak area derived from the ester bond.

[Hue (L value)] Using a spectrophotometer ("SE6000" manufactured by Nippon Denshoku Industries Co., Ltd.), the L value of the polymer was measured.

<Examples 2 and 3> Except that the type of raw material monomer, the amount used (mol %), the catalyst, the heating rate, and the final polymerization temperature are set as shown in Table 1, and the prepolymer is heat-treated (solid phase polymerization) at 290°C and 10 hours, 300°C and 10 hours, 310°C and 10 hours, and 320°C and 10 hours in a nitrogen flow, the same process as in Example 1 is carried out to obtain a polymer. In addition, the same evaluation as in Example 1 is carried out. The evaluation results are shown in Table 1.

<Examples 4 and 5> Except that the type of raw material monomer, the amount used (mol %), the catalyst, the heating rate, and the final polymerization temperature are set as shown in Table 1, the same process as in Example 1 is carried out to obtain a polymer. In addition, the same evaluation as in Example 1 is carried out (the melt viscosity of Example 5 is measured at a temperature of 350°C). The evaluation results are shown in Table 1.

<Comparative Example 1> In a polymerization vessel equipped with a stirrer, a reflux column, a monomer inlet, a nitrogen inlet, and a decompression/outflow line, the following raw monomers, a fatty acid metal salt catalyst, and an acylation agent were loaded, and nitrogen substitution was started. (I) 6-Hydroxy-2-naphthoic acid 0.883 mol (48 mol%) (HNA) (II) 4-Hydroxybenzoic acid 0.037 mol (2 mol%) (HBA) (III) 1,4-phenylenedicarboxylic acid 0.46 mol (25 mol%) (TA) (IV) 4,4'-dihydroxybiphenyl 0.46 mol (25 mol%) (BP) Potassium acetate catalyst 150 ppm Cobalt(III) (2,4-pentanedionato) catalyst 150 ppm Acetic anhydride 1.91 mol (1.04 times the total hydroxyl equivalent of HNA, HBA, and BP) After loading the raw materials, the temperature of the reaction system was raised to 140°C and the reaction was allowed to proceed at 140°C for 1 hour. After that, the temperature was further increased at the speed conditions shown in Table 1, and the final polymerization temperature was set as shown in Table 1. It took 20 minutes to reduce the pressure to 10 Torr (i.e., 1330 Pa), and melt polymerization was carried out while diluting acetic acid, excess acetic anhydride, and other low-boiling components. After the stirring torque reached the specified value, nitrogen was introduced, and the pressure was changed from the reduced pressure state to the pressurized state through normal pressure. The product was discharged from the bottom of the polymerization container and granulated to obtain a granular prepolymer. The obtained prepolymer was heated at 300°C for 5 hours under a nitrogen flow (solid phase polymerization) to obtain the target polymer.

<Comparative Examples 2 and 3> Except that the type of raw material monomer, the amount used (mol %), the catalyst, the heating rate, and the final polymerization temperature were set as shown in Table 1, the same process as in Comparative Example 1 was carried out to obtain a polymer. In addition, the same evaluation as in Example 1 was carried out (the melt viscosity of Comparative Example 3 was measured at a temperature of 350°C). The evaluation results are shown in Table 1.

<Example 6> Using a biaxial extruder, the wholly aromatic polyester obtained in Example 1 was mixed with the following components to obtain a resin composition. The extrusion conditions were as described below. The blending amount of each component was as shown in Table 2. Fiber-like filler Grinded fiber: EPH-80M manufactured by Nippon Electric Glass (Co., Ltd.), fiber diameter 10.5μm, average fiber length 80μm (manufacturer nominal value) Plate-like filler Mica: AB-25S manufactured by Yamaguchi Mica Industry (Co., Ltd.), average particle size 25μm

(Extrusion conditions) The temperature of the cylinder installed at the main feed port was set to 250°C, and the temperature of the other cylinders was set to 360°C. The wholly aromatic polyester was supplied from the main feed port. The filler was supplied from the side feed port.

<Comparative Example 4> Except for using the wholly aromatic polyester obtained in Comparative Example 1, the same procedure as in Example 1 was followed to obtain a resin composition.

(Bending test) The resin composition was injection molded under the following molding conditions to obtain a molded product with a thickness of 130 mm × 13 mm × 0.8 mm. The bending strength, bending elasticity, and bending strain were measured in accordance with ASTM D790. The evaluation results are shown in Table 2. ＜Molding conditions＞ Molding machine: Sumitomo Heavy Industries, SE100DU Cylinder temperature: 370°C Mold temperature: 80°C Injection speed: 33 mm/sec Pressure holding: 50 MPa

[Table 1] Embodiment 1 Embodiment 2 Embodiment 3 Embodiment 4 Embodiment 5 Comparative example 1 Comparative example 2 Comparative example 3 Monomer composition (usage amount) HNA Mole % 48 48 48 40 60 48 40 60 HBA Mole % 2 2 2 6 6 2 6 6 TA Mole % 25 25 25 27 17 25 27 17 BP Mole % 25 25 25 27 17 25 27 17 total Mole % 100 100 100 100 100 100 100 100 Catalyst 1-Methimazole ppm 1100 1100 0 1100 1100 0 0 0 Potassium acetate ppm 0 0 150 0 0 150 150 150 Cobalt(III)2,4-pentanedionate ppm 0 0 150 0 0 150 150 150 Heating rate ℃/min 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 Final polymerization temperature ℃ 300 315 320 300 300 360 360 360 Melting point ℃ 348 356 355 348 318 348 347 317 Melt viscosity Pa･s twenty three 51 54 29 26 26 25 twenty one Ketone bond Mole % 0.0001 0.0001 0.0002 0.0001 0.0001 0.12 0.1 0.13 L value - 68 68 67 65 67 57 59 60

[Table 2] Embodiment 6 Comparative example 4 Fully aromatic polyester Monomer composition (usage amount) HNA Mole % 48 48 HBA Mole % 2 2 TA Mole % 25 25 BP Mole % 25 25 total Mole % 100 100 Catalyst 1-Methimazole ppm 1100 0 Potassium acetate ppm 0 150 Cobalt(III)2,4-pentanedionate ppm 0 150 Heating rate ℃/min 0.5 0.5 Final polymerization temperature ℃ 300 360 Melting point ℃ 348 348 Melt viscosity Pa･s twenty three 26 Ketone bond Mole % 0.0001 0.12 L value - 68 57 Resin composition Fully aromatic polyester Quality% 68 68 Filler Abrasive Fiber Quality% 10 10 Mica Quality% twenty two twenty two total Quality% 100 100 Bending strength MPa 196 199 Bending elasticity MPa 14230 14490 Bending strain % 2.70 2.48

In addition, as shown in Table 2, the bending strain of Example 6 having a ketone bond content of 0.0001 mol% is larger than that of Comparative Example 4 having a ketone bond content of 0.12 mol%. This is judged to mean that the greater the bending strain, the better the toughness, and thus means that the problem of the present invention has been solved.

without.

without.

without.

Claims (9)

A wholly aromatic polyester, characterized in that it is a wholly aromatic polyester composed of the following constituent units (I), (II), (III) and (IV) as essential constituent components: the content of the constituent unit (I) is 40-75 mol% relative to all the constituent units; the content of the constituent unit (II) is 0.5-7.5 mol% relative to all the constituent units; the content of the constituent unit (III) is 8.5-30 mol% relative to all the constituent units; the content of the constituent unit (IV) is 8.5-30 mol% relative to all the constituent units; the total content of the constituent units (I), (II), (III) and (IV) is 100 mol% relative to all the constituent units. The molecule has an ester bond or a combination of an ester bond and a ketone bond, wherein the amount of the ketone bond is 0.0000 to 0.0010 mol% relative to the total of the ester bond and the ketone bond, wherein the wholly aromatic polyester has an L value of 65 or more, [Chemical 1] . A polyester resin composition contains the wholly aromatic polyester as claimed in claim 1. A polyester molded product is obtained by molding the wholly aromatic polyester or polyester resin composition as claimed in claim 1 or 2. A method for producing a wholly aromatic polyester, which is a method for producing a wholly aromatic polyester, is characterized in that it comprises: A step of acylating 6-hydroxy-2-naphthoic acid, 4-hydroxybenzoic acid, and 4,4'-dihydroxybiphenyl with fatty acid anhydride, and then esterifying with 1,4-phenylenedicarboxylic acid, Relative to all monomers composed of 6-hydroxy-2-naphthoic acid, 4-hydroxybenzoic acid, 1,4-phenylenedicarboxylic acid, and 4,4'-dihydroxybiphenyl, The amount of 6-hydroxy-2-naphthoic acid used is 40-75 mol%, The amount of 4-hydroxybenzoic acid used is 0.5-7.5 mol%, The amount of 1,4-phenylenedicarboxylic acid used is 8.5-30 mol%, The amount of 4,4'-dihydroxybiphenyl used is 8.5 to 30 mol%, the total amount of 6-hydroxy-2-naphthoic acid, 4-hydroxybenzoic acid, 1,4-phenylenedicarboxylic acid, and 4,4'-dihydroxybiphenyl used is 100 mol%, the final polymerization temperature is below 320°C, wherein the above-mentioned method for producing wholly aromatic polyester has an L value of 65 or more. A method for producing a wholly aromatic polyester as claimed in claim 4, wherein a nitrogen-containing heterocyclic compound is used as a catalyst. A method for producing a wholly aromatic polyester as claimed in claim 5, wherein the nitrogen-containing heterocyclic compound is 1-methylimidazole. A method for producing a wholly aromatic polyester as claimed in claim 4, wherein a potassium compound and/or a trivalent cobalt compound is used as a catalyst. A method for producing a wholly aromatic polyester as claimed in claim 7, wherein the potassium compound is potassium acetate. A method for producing a wholly aromatic polyester as claimed in claim 7 or 8, wherein the trivalent cobalt compound is cobalt (III) bis(2,4-pentanedionato).