Liquid crystal polyester, method for manufacturing liquid crystal polyester, and molded product

Abstract

To provide a liquid crystal polyester that has high thermal stability and generates few defects due to unmelted material during molding. [Solution] A liquid crystal polyester containing a first monomer unit having a naphthalene ring, a second monomer unit having a naphthalene ring and different from the first monomer unit, and a third monomer unit derived from an aromatic dicarboxylic acid and different from the first monomer unit and the second monomer unit, wherein the alkali metal ion content is 5 to 40 ppm by mass.

Description

[Technical Field]

[0001] This disclosure relates to liquid crystal polyester, a method for manufacturing liquid crystal polyester, and molded articles. [Background technology]

[0002] Liquid crystal polyester has excellent electrical properties and is used in a variety of applications.

[0003] For example, Patent Document 1 describes that an aromatic liquid crystal polyester having a predetermined repeating unit has low dielectric loss and excellent processability into a film shape. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2005-272810 [Overview of the project] [Problems that the invention aims to solve]

[0005] In recent years, there has been a growing demand for improvements in the properties of liquid crystal polyester itself, from the perspective of expanding into a wider range of applications and applying it to more intricate components.

[0006] The object of this disclosure is to provide a liquid crystal polyester that has high thermal stability and generates few defects due to unmelted material during molding. Another object of this disclosure is to provide a method for manufacturing the liquid crystal polyester and a molded article containing the liquid crystal polyester. [Means for solving the problem]

[0007] This disclosure provides, for example, the following [1] to [7]. [1] A first monomer unit having a naphthalene ring, A second monomer unit having a naphthalene ring and different from the first monomer unit, A monomer unit derived from an aromatic dicarboxylic acid, comprising a third monomer unit different from the first monomer unit and the second monomer unit, It contains, Liquid crystal polyester containing alkali metal ions in a concentration of 5 to 40 ppm by mass. [2] The liquid crystal polyester according to [1], wherein the alkali metal ion comprises a sodium ion. [3] The first monomer unit has a naphthalene ring and two carbonyl groups bonded to the naphthalene ring, The liquid crystal polyester according to [1] or [2], wherein the second monomer unit comprises a naphthalene ring, a carbonyl group bonded to the naphthalene ring, and an oxygen atom bonded to the naphthalene ring. [4] The liquid crystal polyester according to any one of [1] to [3], wherein the third monomer unit is a monomer unit derived from terephthalic acid or isophthalic acid. [5] The process comprises a step of polymerizing monomer components in a reaction system containing alkali metal ions and a basic catalyst, The monomer component comprises a first monomer having a naphthalene ring, a second monomer having a naphthalene ring and different from the first monomer, and a third monomer which is an aromatic dicarboxylic acid and different from the first monomer and the second monomer. The alkali metal ion content is 4 to 35 ppm by mass per 100 parts by mass of the monomer component. A method for manufacturing liquid crystal polyester. [6] The manufacturing method according to [5], wherein the liquid crystal polyester is the liquid crystal polyester described in any one of [1] to [4]. [7] A molded article containing liquid crystal polyester as described in any one of [1] to [4]. [Effects of the Invention]

[0008] This disclosure provides a liquid crystal polyester that has high thermal stability and generates few defects due to unmelted material during molding. This disclosure also provides a method for manufacturing the liquid crystal polyester and a molded article containing the liquid crystal polyester. [Modes for carrying out the invention]

[0009] Preferred embodiments of this disclosure are described in detail below.

[0010] (Liquid crystal polyester) The liquid crystal polyester of this embodiment contains a first monomer unit having a naphthalene ring, a second monomer unit having a naphthalene ring but different from the first monomer unit, and a third monomer unit derived from an aromatic dicarboxylic acid, which is different from the first monomer unit and the second monomer unit. In the liquid crystal polyester of this embodiment, the alkali metal ion content is 5 to 40 ppm by mass.

[0011] The liquid crystal polyester of this embodiment has high thermal stability. Furthermore, because the liquid crystal polyester of this embodiment generates fewer defects due to unmelted material during molding, it can be suitably used in molded products requiring fine detail, molded products where appearance is important, and the like.

[0012] Normally, liquid crystal polyester contains trace amounts of low molecular weight components (e.g., unreacted components, molecules with an extremely low degree of polymerization, etc.). Therefore, when attempting to melt and mold liquid crystal polyester, it is thought that these low molecular weight components aggregate and form nuclei, making it easier for unmelted particles to remain in the molten material. In contrast, in this embodiment, since the liquid crystal polyester contains alkali metal ions at a concentration of 5 ppm or more by mass, it is believed that the alkali metal ions trap the low molecular weight components, inhibiting aggregation and suppressing the generation of unmelted material.

[0013] Furthermore, if a large amount of alkali metal ions are present in the liquid crystal polyester, the alkali metal ions may accelerate the thermal decomposition of the liquid crystal polyester at high temperatures, resulting in poor thermal stability. In contrast, in this embodiment, the alkali metal ion content is 5 to 40 ppm by mass, so a high level of thermal stability is maintained while sufficiently suppressing the generation of defects caused by unmelted material.

[0014] Liquid crystal polyester can be any polyester that exhibits liquid crystal properties in a molten state. Liquid crystal polyester may be a single polymer or a mixture of two or more polymers.

[0015] Liquid crystal polyesters have constituent units (monomer units) derived from raw material monomers. In liquid crystal polyesters, the main monomer units (for example, monomer units of 90 mol% or more, 95 mol% or more, or 99 mol% or more of the total monomer units, preferably all monomer units) may be monomer units derived from aromatic compounds. Liquid crystal polyesters in which all monomer units are monomer units derived from aromatic compounds are also called all-aromatic liquid crystal polyesters.

[0016] In this specification, "derived from" means that in the monomer units of the liquid crystal polyester formed by the polymerization of the raw material monomers, the chemical structure of the functional groups that contribute to polymerization of the raw material monomers has changed, while no other structural changes have occurred. Here, "derived from" is a concept that also includes cases where the product is derived from polymerizable derivatives of the raw material monomers (for example, compounds obtained by converting the functional groups that contribute to polymerization of the raw material monomers into other polymerizable groups).

[0017] Aromatic compounds are compounds having an aromatic ring. Suitable aromatic compounds as starting monomers may have an aromatic ring and two or more polymerizable groups (for example, a hydroxyl group, an amino group, or a carboxyl group, preferably a hydroxyl group or a carboxyl group) bonded to the aromatic ring.

[0018] The aromatic compound may be, for example, a compound represented by the following formula (1-1) (hereinafter also referred to as aromatic compound (1-1)), a compound represented by the following formula (1-2) (hereinafter also referred to as aromatic compound (1-2)), or a compound represented by the following formula (1-3) (hereinafter also referred to as aromatic compound (1-3)). X 1 -Ar 1 -Y 1 (1-1) X 2 -Ar 2 -X 3 (1-2) Y 2 -Ar 3 -Y 3 (1-3) [In the formula, Ar 1 , Ar 2 and Ar 3 each independently represents a phenylene group, a biphenylene group, a condensed polycyclic aromatic hydrocarbon group, or a group represented by the formula (Z-1). Some or all of the hydrogen atoms possessed by Ar 1 , Ar 2 and Ar 3 may be substituted with a halogen atom, an alkyl group or an aryl group. X 1 , X 2 and X 3 each independently represents a hydroxy group or an amino group. Y 1 , Y 2 and Y 3 represents a carboxy group.] -Ar 4 -Z 1 -Ar 5 - (Z-1) [In the formula, Ar 4 and Ar 5 each independently represents a phenylene group or a condensed polycyclic aromatic hydrocarbon group. Z 1 represents an oxygen atom (-O-), a sulfur atom (-S-), a carbonyl group (-CO-), a sulfonyl group (-SO2-) or an alkanediyl group.]

[0019] Monomer units derived from aromatic compounds may be, for example, the monomer unit represented by the following formula (2-1) (hereinafter also referred to as monomer unit (2-1)), the constituent unit represented by the following formula (2-2) (hereinafter also referred to as monomer unit (2-2)), or the constituent unit represented by the following formula (2-3) (hereinafter also referred to as monomer unit (2-3)). It can be said that monomer unit (2-1) is a monomer unit derived from aromatic compound (1-1), monomer unit (2-2) is a monomer unit derived from aromatic compound (1-2), and monomer unit (2-3) is a monomer unit derived from aromatic compound (1-3). -X 11 -Ar 1 -Y 11 - (2-1) -X 12 -Ar 2 -X 13 - (2-2) -Y 12 -Ar 3 -Y 13 - (2-3) [In the formula, Ar 1 Ar 2 and Ar 3 This is synonymous with the above. X 11 , X 12 and X 13 Each of these independently represents either an oxygen atom (-O-) or an imino group (-NH-). 11 , Y 12 and Y 13 This represents a carbonyl group (-CO-).

[0020] The phenylene group may be, for example, a 1,4-phenylene group or a 1,3-phenylene group, and is preferably a 1,4-phenylene group.

[0021] The biphenylene group may be, for example, a 4,4'-biphenylylene group.

[0022] A condensed polycyclic aromatic hydrocarbon group is a group obtained by removing two hydrogen atoms from a condensed polycyclic aromatic hydrocarbon. Examples of condensed polycyclic aromatic hydrocarbons include naphthalene, anthracene, phenanthrene, tetracene, pyrene, triphenylene, perylene, and fluorene. Of these, naphthalene is preferred from the viewpoint of availability and price.

[0023] The condensed polycyclic aromatic hydrocarbon group may be a naphthylene group. The naphthylene group may be, for example, a 2,6-naphthylene group, a 2,7-naphthylene group, or a 1,5-naphthylene group, and is preferably a 2,6-naphthylene group.

[0024] Examples of halogen atoms used as substituents include fluorine, chlorine, bromine, and iodine atoms.

[0025] The alkyl group as a substituent may be linear, branched, or cyclic. The alkyl group may be, for example, an alkyl group having 1 to 10 carbon atoms. Examples of alkyl groups include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, s-butyl group, t-butyl group, n-hexyl group, 2-ethylhexyl group, n-octyl group, n-decyl group, and the like.

[0026] The aryl group as a substituent may be a monocyclic or fused ring. The aryl group may be, for example, an aryl group having 6 to 20 carbon atoms. Examples of aryl groups include phenyl, o-tolyl, m-tolyl, p-tolyl, 1-naphthyl, and 2-naphthyl groups. The aryl group may also be a group in which a hydrogen atom of the aromatic ring is substituted with an alkyl group, such as the tolyl group.

[0027] Ar 1 Ar 2 and Ar 3 The number of substituents it has may be, for example, 0 to 2, 0 or 1, or 0.

[0028] Z 1The alkanediyl group in may be linear or branched. The alkanediyl group may be an alkanediyl group having 1 to 10 carbon atoms. Examples of alkanediyl groups include methylene group, ethanediyl group, propanediyl group (e.g., propane-2,2-diyl group), butanediyl group, octanediyl group (e.g., octane-3,3-diyl group), etc.

[0029] X 1 , X 2 and X 3 Preferably, this is a hydroxyl group. That is, aromatic compound (1-1) may be an aromatic hydroxycarboxylic acid, and aromatic compound (1-2) may be an aromatic diol. Aromatic compound (1-3) may be an aromatic dicarboxylic acid.

[0030] X 11 , X 12 and X 13 Preferably, it is an oxygen atom (-O-).

[0031] The liquid crystal polyester of this embodiment has a first monomer unit having a naphthalene ring, a second monomer unit having a naphthalene ring but different from the first monomer unit, and a third monomer unit derived from an aromatic dicarboxylic acid and different from the first and second monomer units. Such a liquid crystal polyester is prone to the problems caused by aggregation of the low molecular weight components mentioned above, and the above-mentioned effects are particularly pronounced.

[0032] The first monomer unit may be a monomer unit corresponding to formula (2-1) above (monomer unit (2-1)), a monomer unit corresponding to formula (2-2) (monomer unit (2-2)), or a monomer unit corresponding to formula (2-3) (monomer unit (2-3)), and preferably a monomer unit corresponding to formula (2-3).

[0033] The first monomer unit is, for example, Ar 1 The monomer unit (2-1) may be a naphthylene group, and Ar 2 It may also be a monomer unit (2-2) in which the naphthylene group, Ar3 It may also be a monomer unit (2-3) in which the naphthylene group is preferably Ar 3 This is a monomer unit (2-3) in which the naphthylene group is located.

[0034] The first monomer unit can also be described as a monomer unit derived from the first monomer having a naphthalene ring.

[0035] The first monomer may be a compound corresponding to formula (1-1) above (aromatic compound (1-1)), a compound corresponding to formula (1-2) (aromatic compound (1-2)), or a compound corresponding to formula (1-3) (aromatic compound (1-3)), and is preferably a compound corresponding to formula (1-3).

[0036] The first monomer is, for example, Ar 1 (1-1) may be an aromatic compound in which is a naphthylene group, and Ar 2 It may also be an aromatic compound (1-2) in which the group is a naphthylene group, Ar 3 It may also be an aromatic compound (1-3) in which is a naphthylene group, preferably Ar 3 These are aromatic compounds (1-3) in which the naphthylene group is located.

[0037] Examples of the first monomer include 2-hydroxy-6-naphthoic acid, 2,6-naphthalenedicarboxylic acid, 2,6-dihydroxynaphthalene, 1,5-dihydroxynaphthalene, 2-hydroxy-3-naphthoic acid, 1-hydroxy-5-naphthoic acid, and 2,7-naphthalenediol, with 2,6-naphthalenedicarboxylic acid being preferred.

[0038] The second monomer unit may be a monomer unit corresponding to formula (2-1) above (monomer unit (2-1)), a monomer unit corresponding to formula (2-2) (monomer unit (2-2)), or a monomer unit corresponding to formula (2-3) (monomer unit (2-3)), preferably a monomer unit corresponding to formula (2-1) or formula (2-2), and more preferably a monomer unit corresponding to formula (2-1).

[0039] The second monomer unit is, for example, Ar 1 The monomer unit (2-1) may be a naphthylene group, and Ar 2 It may also be a monomer unit (2-2) in which the naphthylene group, Ar 3 It may also be a monomer unit (2-3) in which the naphthylene group is preferably Ar 1 monomer unit (2-1) in which the naphthylene group or Ar 2 The monomer unit (2-2) is a naphthylene group, and more preferably Ar 1 This is the monomer unit (2-1) in which the naphthylene group is located.

[0040] The second monomer can also be described as a monomer unit derived from a second monomer (different from the first monomer) that has a naphthalene ring.

[0041] The second monomer may be a compound corresponding to formula (1-1) above (aromatic compound (1-1)), a compound corresponding to formula (1-2) (aromatic compound (1-2)), or a compound corresponding to formula (1-3) (aromatic compound (1-3)), preferably an aromatic compound corresponding to formula (1-1) or formula (1-2), and more preferably an aromatic compound corresponding to formula (1-1).

[0042] The second monomer is, for example, Ar 1 (1-1) may be an aromatic compound in which is a naphthylene group, and Ar 2 It may also be an aromatic compound (1-2) in which the group is a naphthylene group, Ar 3 It may also be an aromatic compound (1-3) in which is a naphthylene group, preferably Ar 1 Aromatic compounds (1-1) in which the group is a naphthylene group or Ar 2 (1-2) is an aromatic compound in which is a naphthylene group, and more preferably Ar 1 (1-1) is an aromatic compound in which the naphthylene group is located.

[0043] Examples of the second monomer include 2-hydroxy-6-naphthoic acid, 2,6-naphthalenedicarboxylic acid, 2,6-dihydroxynaphthalene, 1,5-dihydroxynaphthalene, 2-hydroxy-3-naphthoic acid, 1-hydroxy-5-naphthoic acid, and 2,7-naphthalenediol, with 2-hydroxy-6-naphthoic acid or 2,6-dihydroxynaphthalene being preferred, and 2-hydroxy-6-naphthoic acid being more preferred.

[0044] The third monomer unit may be, for example, a monomer unit that does not have a naphthalene ring. The third monomer unit may also be a monomer unit corresponding to the above formula (2-3) (monomer unit (2-3)).

[0045] The third monomer unit is, for example, Ar 3 The monomer unit (2-3) may be a phenylene group, a biphenylene group, a condensed polycyclic aromatic hydrocarbon group (excluding naphthylene group), or a group represented by formula (Z-1), and Ar 3 The monomer unit (2-3) may be a phenylene group, a biphenylene group, or a group represented by formula (Z-1), and Ar 3 The monomer unit (2-3) may be a phenylene group or a biphenylene group, and Ar 3 The monomer unit (2-3) may be a phenylene group.

[0046] The third monomer unit is a monomer unit derived from an aromatic dicarboxylic acid, which may be, for example, an aromatic dicarboxylic acid that does not have a naphthalene ring.

[0047] Aromatic dicarboxylic acids are, for example, Ar 3 The aromatic compound (1-3) is a phenylene group, a biphenylene group, a condensed polycyclic aromatic hydrocarbon group (excluding naphthylene group), or a group represented by formula (Z-1), and Ar 3 The compound (1-3) may be an aromatic compound in which is a phenylene group, a biphenylene group, or a group represented by formula (Z-1), and Ar 3It may also be an aromatic compound (1-3) that is a phenylene group or a biphenylene group, Ar 3 It may also be an aromatic compound (1-3) that is a phenylene group.

[0048] The aromatic dicarboxylic acid may be, for example, terephthalic acid or isophthalic acid.

[0049] The liquid crystal polyester of the present embodiment may further have a fourth monomer unit that is a monomer unit derived from an aromatic diol and is different from the first monomer unit and the second monomer unit.

[0050] ' The fourth monomer unit may be, for example, a monomer unit that does not have a naphthalene ring. The fourth monomer unit may also be a monomer unit (monomer unit (2-2)) corresponding to the above formula (2-2). That is, the fourth monomer unit is X 12 and X 13 It may be a monomer unit (2-2) in which is an oxygen atom (-O-).

[0051] The fourth monomer unit is, for example, X 12 and X 13 are oxygen atoms (-O-), and Ar 2 is a phenylene group, a biphenylene group, a condensed polycyclic aromatic hydrocarbon group (excluding a naphthylene group), or a group represented by the formula (Z-1), and X 12 and X 13 are oxygen atoms (-O-), and Ar 2 is a phenylene group, a biphenylene group, or a group represented by the formula (Z-1), and X 12 and X 13 are oxygen atoms (-O-), and Ar 2 is a phenylene group or a biphenylene group, and X 12 and X 13 are oxygen atoms (-O-), and Ar 2 is a phenylene group, and it may be a monomer unit (2-2).

[0052] The fourth monomer unit is a monomer unit derived from an aromatic diol, which may be, for example, an aromatic diol that does not have a naphthalene ring.

[0053] Aromatic diols are, for example, X 2 and X 3 The hydroxyl group is Ar 2 The aromatic compound (1-2) is a phenylene group, a biphenylene group, a condensed polycyclic aromatic hydrocarbon group (excluding naphthylene group), or a group represented by formula (Z-1), X 2 and X 3 The hydroxyl group is Ar 2 It may also be an aromatic compound (1-2) in which is a phenylene group, a biphenylene group, or a group represented by formula (Z-1), X 2 and X 3 The hydroxyl group is Ar 2 It may also be an aromatic compound (1-2) in which is a phenylene group or a biphenylene group, X 2 and X 3 The hydroxyl group is Ar 2 It may also be an aromatic compound (1-2) in which is a phenylene group.

[0054] The aromatic diol may be, for example, hydroquinone or 4,4'-biphenol, and may be hydroquinone.

[0055] The liquid crystal polyester of this embodiment may further have a fifth monomer unit derived from an aromatic hydroxycarboxylic acid, which is different from the first monomer unit and the second monomer unit.

[0056] The fifth monomer unit may be, for example, a monomer unit that does not have a naphthalene ring. The fifth monomer unit may also be a monomer unit corresponding to the above formula (2-1) (monomer unit (2-1)). That is, the fifth monomer unit is X 11 It may be a monomer unit (2-1) in which is an oxygen atom (-O-).

[0057] The fifth monomer unit is, for example, X 11 This is an oxygen atom (-O-), and Ar 1 The monomer unit (2-1) is a phenylene group, a biphenylene group, a condensed polycyclic aromatic hydrocarbon group (excluding naphthylene group), or a group represented by formula (Z-1), X 11 This is an oxygen atom (-O-), and Ar 1 It may be a monomer unit (2-1) which is a phenylene group, a biphenylene group, or a group represented by formula (Z-1), X 11 This is an oxygen atom (-O-), and Ar 1 The monomer unit (2-1) may be a phenylene group or a biphenylene group, X 11 This is an oxygen atom (-O-), and Ar 1 It may also be a monomer unit (2-1) in which is a phenylene group.

[0058] The fifth monomer unit is a monomer unit derived from an aromatic hydroxycarboxylic acid, which may be, for example, an aromatic hydroxycarboxylic acid that does not have a naphthalene ring.

[0059] Aromatic hydroxycarboxylic acids are, for example, X 1 The hydroxyl group is Ar 1 The aromatic compound (1-1) is a phenylene group, a biphenylene group, a condensed polycyclic aromatic hydrocarbon group (excluding naphthylene group), or a group represented by formula (Z-1), X 1 The hydroxyl group is Ar 1 It may also be an aromatic compound (1-1) in which is a phenylene group, a biphenylene group, or a group represented by formula (Z-1), X 1 The hydroxyl group is Ar 1 (1-1) may be an aromatic compound in which is a phenylene group or a biphenylene group, X 1 The hydroxyl group is Ar 1 It may also be an aromatic compound (1-1) in which is a phenylene group.

[0060] The aromatic diol may be, for example, hydroquinone or 4,4'-biphenol, and may be hydroquinone.

[0061] The content of the first monomer unit in the liquid crystal polyester may be, for example, 1 mol% or more, 3 mol% or more, 6 mol% or more, or 10 mol% or more, relative to the total amount of monomer units in the liquid crystal polyester. Alternatively, the content of the first monomer unit in the liquid crystal polyester may be, for example, 30 mol% or less, 28 mol% or less, 25 mol% or less, or 20 mol% or less, relative to the total amount of monomer units in the liquid crystal polyester.

[0062] The content of the second monomer unit in the liquid crystal polyester may be, for example, 20 mol% or more, 25 mol% or more, 30 mol% or more, or 35 mol% or more, relative to the total amount of monomer units in the liquid crystal polyester. Alternatively, the content of the second monomer unit in the liquid crystal polyester may be, for example, 90 mol% or less, 85 mol% or less, 80 mol% or less, or 75 mol% or less, relative to the total amount of monomer units in the liquid crystal polyester.

[0063] The content of the third monomer unit in the liquid crystal polyester may be, for example, 1 mol% or more, 2 mol% or more, 3 mol% or more, or 4 mol% or more, relative to the total amount of monomer units in the liquid crystal polyester. Alternatively, the content of the third monomer unit in the liquid crystal polyester may be, for example, 30 mol% or less, 25 mol% or less, 20 mol% or less, or 15 mol% or less, relative to the total amount of monomer units in the liquid crystal polyester.

[0064] When the liquid crystal polyester has a fourth monomer unit, the content of the fourth monomer unit in the liquid crystal polyester may be, for example, 1 mol% or more, 10 mol% or more, 15 mol% or more, or 20 mol% or more, relative to the total amount of monomer units of the liquid crystal polyester. Alternatively, the content of the fourth monomer unit in the liquid crystal polyester may be, for example, 45 mol% or less, 40 mol% or less, 35 mol% or less, or 30 mol% or less, relative to the total amount of monomer units of the liquid crystal polyester.

[0065] When the liquid crystal polyester has a fifth monomer unit, the content of the fifth monomer unit in the liquid crystal polyester may be, for example, 1 mol% or more, 2 mol% or more, 3 mol% or more, or 4 mol% or more, relative to the total amount of monomer units of the liquid crystal polyester. Alternatively, the content of the fifth monomer unit in the liquid crystal polyester may be, for example, 20 mol% or less, 15 mol% or less, 10 mol% or less, or 8 mol% or less, relative to the total amount of monomer units of the liquid crystal polyester.

[0066] In the liquid crystal polyester, the total amount of the first monomer unit and the second monomer unit may be, for example, 21 mol% or more, 28 mol% or more, 36 mol% or more, or 45 mol% or more, relative to the total amount of all monomer units of the liquid crystal polyester. Alternatively, the total amount of the first monomer unit and the second monomer unit in the liquid crystal polyester may be, for example, 90 mol% or less, 85 mol% or less, 80 mol% or less, or 75 mol% or less, relative to the total amount of all monomer units of the liquid crystal polyester.

[0067] In liquid crystal polyester, the total amount of the first monomer unit, the second monomer unit, the third monomer unit, and the fourth monomer unit may be, for example, 90 mol% or more, 95 mol% or more, 97 mol% or more, or 99 mol% or more, or 100 mol%, relative to the total amount of all monomer units of the liquid crystal polyester.

[0068] In this specification, the number of each monomer unit in a liquid crystal polyester is determined by the analytical method described in Japanese Patent Application Publication No. 2000-19168. Specifically, the number of each monomer unit relative to the total number of monomer units can be calculated by depolymerizing the liquid crystal polyester by reacting it with a lower alcohol in a supercritical state and quantifying the depolymerization product (monomers that induce each monomer unit) by liquid chromatography.

[0069] The flow initiation temperature of the liquid crystal polyester may be, for example, 250°C or higher, or 270°C or higher. Alternatively, the flow initiation temperature of the liquid crystal polyester may be, for example, 380°C or lower, or 360°C or lower.

[0070] In this specification, the flow initiation temperature of liquid crystal polyester is measured using a flow tester, and the liquid crystal polyester is subjected to 9.8 MPa (100 kg / cm³). 2 Under a load of ), the liquid crystal polyester is melted while the temperature is increased at a rate of 4°C / min, and the molten liquid crystal polyester is extruded from a nozzle with an inner diameter of 1 mm and a length of 10 mm, at a temperature at which its viscosity is 4800 Pa·s (48000 poise).

[0071] The weight-average molecular weight (Mw) of the liquid crystal polyester may be, for example, 60,000 or more, and from the viewpoint of mechanical strength, it may be 80,000 or more, 100,000 or more, or 120,000 or more. Furthermore, the weight-average molecular weight (Mw) of the liquid crystal polyester may be, for example, 350,000 or less, and from the viewpoint of moldability, it may be 300,000 or less, 250,000 or less, or 200,000 or less.

[0072] In this specification, the weight-average molecular weight (Mw) of liquid crystal polyester is measured by the following method: 5 mg of liquid crystal polyester and 2 mL of pentafluorophenol are placed in a sample bottle and heated to an internal temperature of 120°C to obtain a solution. After the obtained solution is cooled to 50°C, 4 mL of chloroform is added, and after stirring, the solution is filtered using a 0.45 μm pore size filter to obtain the measurement sample. The obtained measurement sample is analyzed by GPC and the weight-average molecular weight on a standard polystyrene basis is calculated.

[0073] In the liquid crystal polyester of this embodiment, the alkali metal ion content is 5 ppm by mass or more, and may be 7 ppm by mass or more, 9 ppm by mass or more, 11 ppm by mass or more, or 13 ppm by mass or more. Also, in the liquid crystal polyester of this embodiment, the alkali metal ion content is 40 ppm by mass or less, and may be 37 ppm by mass or less, 35 ppm by mass or less, 34 ppm by mass or less, 31 ppm by mass or less, 28 ppm by mass or less, 25 ppm by mass or less, or 22 ppm by mass or less. In other words, in the liquid crystal polyester of this embodiment, the alkali metal ion content is, for example, 5 ppm to 40 ppm by mass, 5 ppm to 37 ppm by mass, 5 ppm to 35 ppm by mass, 5 ppm to 34 ppm by mass, 5 ppm to 31 ppm by mass, 5 ppm to 28 ppm by mass, 5 ppm to 25 ppm by mass, 5 ppm to 22 ppm by mass, and 7 ppm to 4 ppm by mass. 0 mass ppm or less, 7 mass ppm or more and 37 mass ppm or less, 7 mass ppm or more and 35 mass ppm or less, 7 mass ppm or more and 34 mass ppm or less, 7 mass ppm or more and 31 mass ppm or less, 7 mass ppm or more and 28 mass ppm or less , 7 mass ppm or more and 25 mass ppm or less, 7 mass ppm or more and 22 mass ppm or less, 9 mass ppm or more and 40 mass ppm or less, 9 mass ppm or more and 37 mass ppm or less, 9 mass ppm or more and 35 mass ppm or less, 9 mass ppm or more 34 mass ppm or less, 9 mass ppm or more and 31 mass ppm or less, 9 mass ppm or more and 28 mass ppm or less, 9 mass ppm or more and 25 mass ppm or less, 9 mass ppm or more and 22 mass ppm or less, 11 mass ppm or more and 40 mass ppm Below, 11 mass ppm or more and 37 mass ppm or less, 11 mass ppm or more and 35 mass ppm or less, 11 mass ppm or more and 34 mass ppm or less, 11 mass ppm or more and 31 mass ppm or less, 11 mass ppm or more and 28 mass ppm or less, 1 1 mass ppm or more and 25 mass ppm or less, 11 mass ppm or more and 22 mass ppm or less, 13 mass ppm or more and 40 mass ppm or less, 13 mass ppm or more and 37 mass ppm or less, 13 mass ppm or more and 35 mass ppm or less, 13 mass ppm It may be at least 13 ppm by mass and at most 31 ppm by mass, at least 13 ppm by mass and at most 28 ppm by mass, at least 13 ppm by mass and at most 25 ppm by mass, or at least 13 ppm by mass and at most 22 ppm by mass.

[0074] In this specification, the alkali metal ion content in liquid crystal polyester is determined by atomic absorption spectrophotometry. This measurement requires the decomposition of organic matter in the sample. The method for decomposing the organic matter may be heating the sample to cause ashing, or dissolving the sample with acid.

[0075] Alkali metal ions include, for example, lithium ions (Li + ), sodium ions (Na + ), or potassium ions (K + ) may be, preferably sodium ions (Na + )

[0076] The liquid crystal polyester of this embodiment can be produced by polymerizing raw material monomers corresponding to the monomer units that constitute it. For example, it can be produced according to the method described in Japanese Patent No. 6439027. Alternatively, the liquid crystal polyester of this embodiment may be produced by the liquid crystal polyester production method described later.

[0077] (Method of manufacturing liquid crystal polyester) The method for producing liquid crystal polyester according to this embodiment comprises a step of polymerizing monomer components in a reaction system containing alkali metal ions and a basic catalyst.

[0078] In this embodiment, the monomer component includes a first monomer having a naphthalene ring, a second monomer having a naphthalene ring and different from the first monomer, and a third monomer that is an aromatic dicarboxylic acid and different from the first monomer and the second monomer.

[0079] Furthermore, in this embodiment, the alkali metal ion content in the reaction system is 4 to 35 ppm by mass per 100 parts by mass of the monomer component.

[0080] According to the liquid crystal polyester manufacturing method of this embodiment, liquid crystal polyester with high thermal stability and minimal generation of defects due to unmelted material during molding can be easily produced.

[0081] In the manufacturing method of this embodiment, the presence of a predetermined amount of alkali metal ions in the reaction system promotes the polymerization reaction by the basic catalyst. This reduces the amount of low molecular weight components (e.g., unreacted components, molecules with an extremely low degree of polymerization, etc.) that contribute to the generation of unmelted material during molding, and is thought to reduce the generation of defects caused by unmelted material.

[0082] Furthermore, the manufacturing method of this embodiment makes it easy to obtain liquid crystal polyester containing a predetermined amount of alkali metal ions (i.e., the liquid crystal polyester described above). The effects of liquid crystal polyester containing a predetermined amount of alkali metal ions are as described above, and from this point of view as well, it can be said that the liquid crystal polyester produced by the manufacturing method of this embodiment exhibits excellent effects.

[0083] In the manufacturing method of this embodiment, the first monomer, the second monomer, and the third monomer may be compounds that, by polymerization, form the first monomer unit, the second monomer unit, and the third monomer unit in the liquid crystal polyester described above.

[0084] In the manufacturing method of this embodiment, the first monomer, second monomer unit, and third monomer are the same as the first monomer, second monomer unit, and third monomer unit described in the above-mentioned explanation of liquid crystal polyester.

[0085] In the manufacturing method of this embodiment, the monomer component may further contain compounds other than the first monomer, the second monomer, and the third monomer. For example, the monomer component may further contain a fourth monomer that is an aromatic diol and is different from the first monomer and the second monomer. Alternatively, the monomer component may further contain a fifth monomer that is an aromatic hydroxycarboxylic acid and is different from the first monomer and the second monomer.

[0086] In the manufacturing method of this embodiment, the fourth monomer may be a compound that forms the fourth monomer unit in the liquid crystal polyester described above by polymerization. In this embodiment, the fourth monomer can be the same as the fourth monomer described in the description of the liquid crystal polyester described above.

[0087] In the manufacturing method of this embodiment, the fifth monomer may be a compound that forms the fifth monomer unit in the liquid crystal polyester described above by polymerization. In this embodiment, the fifth monomer can be the same as the fifth monomer described in the description of the liquid crystal polyester described above.

[0088] The content of each monomer in the monomer component may be adjusted as appropriate, for example, so that the content of each monomer unit in the liquid crystal polyester falls within the range of the content described in the above-mentioned explanation for liquid crystal polyester.

[0089] The content of the first monomer in the monomer component may be, for example, 1 mol% or more, 3 mol% or more, 6 mol% or more, or 10 mol% or more, based on the total amount of the monomer component. Alternatively, the content of the first monomer in the monomer component may be, for example, 30 mol% or less, 28 mol% or less, 25 mol% or less, or 20 mol% or less, based on the total amount of the monomer component.

[0090] The content of the second monomer in the monomer component may be, for example, 20 mol% or more, 25 mol% or more, 30 mol% or more, or 35 mol% or more, based on the total amount of the monomer component. Alternatively, the content of the second monomer in the monomer component may be, for example, 90 mol% or less, 85 mol% or less, 80 mol% or less, or 75 mol% or less, based on the total amount of the monomer component.

[0091] The content of the third monomer in the monomer component may be, for example, 1 mol% or more, 2 mol% or more, 3 mol% or more, or 4 mol% or more, based on the total amount of the monomer component. Alternatively, the content of the third monomer in the monomer component may be, for example, 30 mol% or less, 25 mol% or less, 20 mol% or less, or 15 mol% or less, based on the total amount of the monomer component.

[0092] When the monomer component contains a fourth monomer, the content of the fourth monomer in the monomer component may be, for example, 1 mol% or more, 10 mol% or more, 15 mol% or more, or 20 mol% or more, based on the total amount of the monomer component. Alternatively, the content of the fourth monomer in the monomer component may be, for example, 45 mol% or less, 40 mol% or less, 35 mol% or less, or 30 mol% or less, based on the total amount of the monomer component.

[0093] When the monomer component contains a fifth monomer, the content of the fifth monomer in the monomer component may be, for example, 1 mol% or more, 2 mol% or more, 3 mol% or more, or 4 mol% or more, based on the total amount of the monomer component. Alternatively, the content of the fifth monomer in the monomer component may be, for example, 20 mol% or less, 15 mol% or less, 10 mol% or less, or 8 mol% or less, based on the total amount of the monomer component.

[0094] The total amount of the first monomer and the second monomer in the monomer component may be, for example, 21 mol% or more, 28 mol% or more, 36 mol% or more, or 45 mol% or more, based on the total amount of the monomer component. Alternatively, the total amount of the first monomer and the second monomer in the monomer component may be, for example, 90 mol% or less, 85 mol% or less, 80 mol% or less, or 75 mol% or less, based on the total amount of the monomer component.

[0095] The total amount of the first monomer, the second monomer, the third monomer, and the fourth monomer in the monomer component may be, for example, 90 mol% or more, 95 mol% or more, 97 mol% or more, or 99 mol% or more, or 100 mol%, based on the total amount of the monomer component.

[0096] Alkali metal ions include, for example, lithium ions (Li + ), sodium ions (Na + ), or potassium ions (K + ) may be, preferably sodium ions (Na + )

[0097] The alkali metal ion content in the reaction system is 4 ppm by mass or more per 100 parts by mass of monomer components, and may be 5 ppm by mass or more, 7 ppm by mass or more, 10 ppm by mass or more, or 13 ppm by mass or more. Alternatively, the alkali metal ion content in the reaction system is 35 ppm by mass or less per 100 parts by mass of monomer components, and may be 32 ppm by mass or less, 29 ppm by mass or less, 26 ppm by mass or less, 23 ppm by mass or less, or 20 ppm by mass or less. That is, the content of alkali metal ions in the reaction system is, for example, 4 mass ppm to 35 mass ppm, 4 mass ppm to 32 mass ppm, 4 mass ppm to 29 mass ppm, 4 mass ppm to 26 mass ppm, 4 mass ppm to 23 mass ppm, 4 mass ppm to 20 mass ppm, based on 100 parts by mass of the monomer component. Bottom, 5 mass ppm to 35 mass ppm, 5 mass ppm to 32 mass ppm, 5 mass ppm to 29 mass ppm, 5 mass ppm to 26 mass ppm, 5 mass ppm to 23 mass ppm, 5 mass ppm to 20 mass ppm, 7 mass ppm to 35 mass ppm, 7 mass ppm to 32 mass ppm, 7 mass ppm m to 29 mass ppm, 7 mass ppm to 26 mass ppm, 7 mass ppm to 23 mass ppm, 7 mass ppm to 20 mass ppm, 10 mass ppm to 35 mass ppm, 10 mass ppm to 32 mass ppm, 10 mass ppm to 29 mass ppm, 10 mass ppm to 26 mass ppm, 10 mass ppm 23 mass ppm or less, 10 mass ppm or more and 20 mass ppm or less, 13 mass ppm or more and 35 mass ppm or less, 13 mass ppm or more and 32 mass ppm or less, 13 mass ppm or more and 29 mass ppm or less, 13 mass ppm or more and 26 mass ppm or less, 13 mass ppm or more and 23 mass ppm or less, or 13 mass ppm or more and 20 mass ppm or less.

[0098] The amount of alkali metal ions in the reaction system may be adjusted as appropriate, for example, so that the amount of alkali metal ions in the liquid crystal polyester falls within the range of the amounts described in the above-mentioned explanation for liquid crystal polyester.

[0099] Alkali metal ions may be present in the reaction system by adding a compound containing alkali metal ions (for example, sodium acetate). Alternatively, alkali metal ions may be present in the reaction system as impurities contained in monomer components, etc.

[0100] The basic catalyst can be any catalyst that can promote the condensation polymerization of a carboxyl group and a hydroxyl group, or the reaction between a hydroxyl group acylated with an acylating agent (described later) and a carboxyl group.

[0101] Examples of basic catalysts include heterocyclic compounds represented by the following formula (A) (hereinafter referred to as heterocyclic compound (A)). [ka]

[0102] In formula (A), R 1 , R 2 , R 3 and R 4 Each of these independently represents a hydrogen atom, a C1-C4 alkyl group, a hydroxymethyl group, a cyano group, a cyanoalkyl group with C1-C4 alkyl groups, a cyanoalkoxy group with C1-C4 alkoxy groups, a carboxyl group, an amino group, a C1-C4 aminoalkyl group, a C1-C4 aminoalkoxy group, a phenyl group, a benzyl group, a phenylpropyl group, or a formyl group.

[0103] As for heterocyclic compounds (A), R 1 is an alkyl group having 1 to 4 carbon atoms, and R 2 , R 3 and R 4 Imidazole derivatives in which the atom is a hydrogen atom are preferred. By using such compounds as basic catalysts, the reactivity of the acylation reaction with the acylating agent described later, and the reactivity of the reaction between the acylated hydroxyl group and the carboxyl group can be improved more efficiently.

[0104] As the heterocyclic compound (A), it is preferable to use either 1-methylimidazole or 1-ethylimidazole, or both, because they are readily available.

[0105] The amount of basic catalyst in the reaction system may be, for example, 0.005 parts by mass or more, or 0.05 parts by mass or more, per 100 parts by mass of monomer component. Alternatively, the amount of basic catalyst in the reaction system may be, for example, 1 part by mass or less, or 0.5 parts by mass or less, per 100 parts by mass of monomer component.

[0106] The reaction system may contain additional acyling agents. Any acyling agent capable of acyling phenolic hydroxyl groups in the monomer component is acceptable.

[0107] The reaction system contains an acylating agent, which causes the acylated hydroxyl groups and carboxyl groups to undergo transesterification and polymerize, resulting in a liquid crystal polyester.

[0108] The acylating agent may be, for example, a fatty acid anhydride (e.g., acetic anhydride).

[0109] The amount of acylating agent used may be, for example, 1 equivalent or more, 1.03 equivalent or more, or 1.05 equivalent or more, relative to the total amount of phenolic hydroxyl groups contained in the monomer components. Alternatively, the amount of acylating agent used may be, for example, 1.2 equivalent or less, 1.15 equivalent or less, 1.12 equivalent or less, or 1.1 equivalent or less, relative to the total amount of phenolic hydroxyl groups contained in the monomer components.

[0110] The conditions for the polymerization reaction are not particularly limited. The polymerization reaction may include, for example, (i) acylation and (ii) transesterification.

[0111] (i) The acylation may be carried out, for example, at 130°C to 180°C (preferably 140°C to 160°C) for 30 minutes to 1 hour (preferably 1 to 5 hours).

[0112] (ii) Polymerization by transesterification may be carried out, for example, after the acylation described in (i) above, while increasing the temperature to 400°C (preferably 350°C) at a heating rate of 0.1 to 50°C / min (preferably 0.3 to 5°C / min).

[0113] The manufacturing method of this embodiment may further include a step of increasing the molecular weight of the polymer obtained in the above step.

[0114] Molecular weight increase may be carried out, for example, by solid-phase polymerization. The conditions for solid-phase polymerization are not particularly limited, and may be adjusted as appropriate, for example, so that the flow initiation temperature of the resulting liquid crystal polyester falls within the range described in the above-mentioned explanation of liquid crystal polyester.

[0115] The liquid crystal polyester of this embodiment can be suitably used as a molding material for obtaining molded articles. The liquid crystal polyester may also be used, for example, as pellets.

[0116] The liquid crystal polyester of this embodiment may also be used as a composition (liquid crystal polyester composition) mixed with other components.

[0117] The liquid crystal polyester composition may contain, for example, one or more resins other than liquid crystal polyester. Examples of such resins include polyolefins, cyclic polyolefins, polyvinyl chloride, polysulfones, (meth)acrylic resins, polyphenylene ether resins, polyacetal resins, polyamide resins, imide resins, cellulose resins, polyether ether ketone resins, fluororesins, polycarbonate resins, styrene resins, thermosetting resins, and the like.

[0118] Furthermore, the liquid crystal polyester composition may further contain inorganic fillers, colorants, dispersants, plasticizers, antioxidants, curing agents, flame retardants, heat stabilizers, ultraviolet absorbers, antistatic agents, surfactants, lubricants, mold release agents, and the like.

[0119] Liquid crystal polyester compositions can be suitably used as molding materials. Liquid crystal polyester compositions may be used, for example, as pellets.

[0120] The molded article of this embodiment may be a molded article containing the above-described liquid crystal polyester, or a molded article containing the above-described liquid crystal polyester composition.

[0121] The molded article of this embodiment can be obtained, for example, by molding the above-mentioned liquid crystal polyester or liquid crystal polyester composition into a desired shape and performing processing as necessary.

[0122] As a method for molding molded products, melt molding is preferred. Examples of melt molding methods include injection molding, extrusion molding, compression molding, blow molding, vacuum molding, foam molding, and press molding.

[0123] The molded products of this embodiment may include, for example, connectors, sockets, relay components, coil bobbins, optical pickups, oscillators, semiconductor packages, IC trays, wafer carriers, household electrical appliance components, lighting fixture components, audio product components, ferrules for optical cables, telephone components, facsimile components, modem components, separation claws, heater holders, impellers, fan gears, gears, bearings, motor components, motor cases, engine components, engine room components, electrical components, automotive interior components, microwave cooking pots, heat-resistant tableware, flooring materials, wall materials, beams, columns, roofing materials, aircraft components, spacecraft components, space equipment components, nuclear reactors, marine facility components, cleaning jigs, optical instrument components, valves, pipes, nozzles, filters, medical equipment components, medical materials, sensor components, sanitary fixtures, sports equipment, leisure goods, etc.

[0124] While preferred embodiments of this disclosure have been described above, this disclosure is not limited to the embodiments described above. [Examples]

[0125] The present disclosure will be described in more detail below with reference to examples, but the present disclosure is not limited to these examples.

[0126] (Example A-1) In a reactor equipped with a stirrer, torque meter, nitrogen gas inlet tube, thermometer, and reflux condenser, 1035.0 g (5.5 mol) of 2-hydroxy-6-naphthoic acid, 378.3 g (1.75 mol) of 2,6-naphthalenedicarboxylic acid (BASF), 83.1 g (0.5 mol) of terephthalic acid, 255.2 g of hydroquinone, 1226.87 g (12 mol) of acetic anhydride, 0.17 g of 1-methylimidazole, and 0.0288 g of sodium acetate were added. After thoroughly purging the reactor with nitrogen gas, the temperature was raised to 140°C over 30 minutes under a nitrogen gas stream, and the temperature was maintained and refluxed for 1 hour. Subsequently, the temperature was raised to 310°C over 5 hours while distilling off the distilled by-product acetic acid. The reaction was considered complete when an increase in torque was observed, and the contents were removed. The contents were cooled to room temperature, pulverized in a coarse grinder, and then heated under a nitrogen atmosphere from room temperature to 250°C over 1 hour, then heated from 250°C to 285°C over 5 hours and 50 minutes, and held at 285°C for 6 hours to allow the polymerization reaction to proceed in a solid layer to obtain liquid crystal polyester (A-1). The flow initiation temperature of the obtained liquid crystal polyester (A-1) was 323°C.

[0127] (Example A-2) Except for changing the amount of sodium acetate to 0.0575 g, the reflux process was carried out in the same manner as in Example A-1. Subsequently, liquid crystal polyester (A-2) was obtained in the same manner as in Example A-1. The flow initiation temperature of the obtained liquid crystal polyester (A-2) was 322°C.

[0128] (Example A-3) Except for changing the amount of sodium acetate to 0.115 g, the reflux process was carried out in the same manner as in Example A-1. Subsequently, liquid crystal polyester (A-3) was obtained in the same manner as in Example A-1. The flow initiation temperature of the obtained liquid crystal polyester (A-3) was 323°C.

[0129] (Comparative Example X-1) Except for the absence of sodium acetate, the reflux process was carried out in the same manner as in Example A-1. Subsequently, the temperature was raised to 310°C over 5 hours while distilling off the distilled by-product acetic acid. The reaction was considered complete when an increase in torque was observed, and the contents were removed. The contents were cooled to room temperature, ground in a coarse grinder, and then, under a nitrogen atmosphere, the temperature was raised from room temperature to 250°C over 1 hour, then from 250°C to 294°C over 7 hours and 20 minutes, and held at 294°C for 6 hours to allow the polymerization reaction in the solid layer to proceed, yielding liquid crystal polyester (X-1). The flow initiation temperature of the obtained liquid crystal polyester (X-2) was 313°C.

[0130] (Comparative Example X-2) Except for changing the amount of sodium acetate to 0.23 g, the reflux process was carried out in the same manner as in Example A-1. Subsequently, liquid crystal polyester (X-2) was obtained in the same manner as in Example A-1. The flow initiation temperature of the obtained liquid crystal polyester (X-2) was 320°C.

[0131] The liquid crystal polyesters obtained in the examples and comparative examples were evaluated by the following method. The results are shown in Table 1.

[0132] (Evaluation of unmelted material) The number of unmelted particles in a filamentous sample was evaluated using a Toyo Seiki capillary rheometer (Capillograph 1D). A die with a diameter of 1 mm and a length of 10 mm was attached to the capillary rheometer, set to 340°C, and the sample was placed inside and heated for 3 minutes. Then, the piston was lowered at an extrusion speed of 5 mm / min to discharge the molten resin from the die. The discharged resin was taken up at a speed of 20 mm / min to create a filamentous sample with a thickness of approximately 200 μm. The spherical unmelted particles present in the filamentous sample were counted using a microscope.

[0133] (Heat resistance evaluation (1)) The temperature at which the weight decreased by 5% was evaluated using a Shimadzu TGA-50 weight measuring device. Specifically, the temperature was increased from room temperature to 800°C in an air atmosphere at a rate of 10°C / min. Using the weight at 100°C as a baseline, the temperature at which the weight decreased by 5% was defined as the 5% weight decrease temperature.

[0134] In Table 1, "Amount of Na in the reaction system (mass ppm)" indicates the amount of sodium ions (mass ppm) per 100 parts by mass of monomer components in the reaction system. Also, in Table 1, "Amount of Na in the liquid crystal polyester (mass ppm)" indicates the amount of sodium ions (mass ppm) in the liquid crystal polyester calculated from the amount of sodium in the reaction system.

[0135] [Table 1]

[0136] As shown in Table 1, Examples A-1 to A-3 yielded liquid crystal polyesters with a high 5% weight loss temperature and low unmelted material during molding. In contrast, Comparative Example X-1 generated a significantly large amount of unmelted material, and Comparative Example X-2 had a low 5% weight loss temperature of less than 505°C. These results confirm that by incorporating alkali metal ions into liquid crystal polyester, it is possible to reduce unmelted material during molding while maintaining high thermal stability.

Claims

1. A first monomer unit having a naphthalene ring, A second monomer unit having a naphthalene ring and different from the first monomer unit, A monomer unit derived from an aromatic dicarboxylic acid, comprising a third monomer unit different from the first monomer unit and the second monomer unit, It contains, Liquid crystal polyester having an alkali metal ion content of 5 to 40 ppm by mass.

2. The liquid crystal polyester according to claim 1, wherein the alkali metal ions include sodium ions.

3. The first monomer unit has a naphthalene ring and two carbonyl groups bonded to the naphthalene ring, The second monomer unit comprises a naphthalene ring, a carbonyl group bonded to the naphthalene ring, and an oxygen atom bonded to the naphthalene ring. The liquid crystal polyester according to claim 1.

4. The liquid crystal polyester according to claim 1, wherein the third monomer unit is a monomer unit derived from terephthalic acid or isophthalic acid.

5. The process comprises a step of polymerizing monomer components in a reaction system containing alkali metal ions and a basic catalyst, The monomer component comprises a first monomer having a naphthalene ring, a second monomer having a naphthalene ring and different from the first monomer, and a third monomer which is an aromatic dicarboxylic acid and different from the first monomer and the second monomer. The alkali metal ion content is 4 to 35 ppm by mass per 100 parts by mass of the monomer component. A method for manufacturing liquid crystal polyester.

6. The manufacturing method according to claim 5, wherein the liquid crystal polyester is the liquid crystal polyester described in any one of claims 1 to 4.

7. A molded article comprising the liquid crystal polyester described in any one of claims 1 to 4.

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