Liquid crystal polyester composition, method for producing liquid crystal polyester composition, and method for producing injection-molded article

Abstract

To provide a liquid crystal polyester composition that can be injection-molded with a short plasticization time.SOLUTION: A liquid crystal polyester composition includes: liquid crystal polyester; and a fatty acid metal salt, where the fatty acid metal salt includes a fatty acid metal salt having a carbon number of the fatty acid of 20 or less, and the residue on a sieve having a nominal opening of 106 μm designated by JIS Z 8801 measured in accordance with JIS K 0069 of the fatty acid metal salt is 0-80 mass% relative to a total content mass of the fatty acid metal salt. The liquid crystal polyester composition includes a pellet containing the liquid polyester, where at least a part of the fatty acid metal salt is preferably attached to the surface of the pellet.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a liquid crystal polyester composition, a method for producing a liquid crystal polyester composition, and a method for producing an injection-molded article. [Background technology]

[0002] Liquid crystal polyesters are generally called melt liquid crystal (thermotropic liquid crystal) polymers, and due to their unique behavior, they have excellent melt fluidity and, depending on their structure, can withstand heat distortion at temperatures of over 300°C. Taking advantage of their high fluidity and heat resistance, liquid crystal polyesters are used in molded products for applications such as electronic components, automotive parts, office equipment parts, and heat-resistant tableware. In recent years, electronic devices have become increasingly smaller and thinner, with the trend toward smaller and thinner electronic components, such as connectors, seeing increasing adoption of liquid crystal polyesters.

[0003] In recent years, in the production of injection-molded articles using liquid crystal polyester resin pellets, long-term continuous molding is sometimes performed under injection molding conditions with shortened molding cycles to improve productivity. In injection molding, the resin is plasticized and metered by rotating a screw. In such continuous molding of liquid crystal polyester resin, it is important to keep the plasticization time (also called the metering time) short during injection molding. Longer plasticization times or variations in the plasticization time during molding can affect the dimensions and appearance of the molded article.

[0004] To address this issue, Patent Document 1 describes pellets from which burrs have been removed in order to stabilize the plasticization time during molding of a molded body. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-177007 Summary of the Invention [Problem to be solved by the invention]

[0006] However, there is still room for improvement in providing molding materials that can be injection molded with a short plasticization time.

[0007] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a liquid crystal polyester composition that can shorten the plasticization time in injection molding. Another object of the present invention is to provide a method for producing the liquid crystal polyester composition. Another object of the present invention is to provide a method for producing an injection-molded article using the liquid crystal polyester composition as a molding material. [Means for solving the problem]

[0008] As a result of intensive research to solve the above problems, the inventors have found that it is possible to provide a liquid crystal polyester composition that can shorten the plasticization time in injection molding by containing a liquid crystal polyester, a specific sieve residue, and a fatty acid metal salt having a specific number of carbon atoms, and have thus completed the present invention. That is, the present invention has the following aspects.

[0009] <1> The liquid crystal composition includes a liquid crystal polyester and a fatty acid metal salt, The fatty acid metal salt includes a fatty acid metal salt having a fatty acid having 20 or less carbon atoms, The liquid crystal polyester composition, wherein the sieve residue of the fatty acid metal salt measured in accordance with JIS K 0069 on a sieve having a nominal mesh size of 106 μm as specified in JIS Z 8801 is 0 to 80 mass % based on the total mass of the fatty acid metal salt. <2> The fatty acid metal salt includes a fatty acid metal salt having a carbon number of 16 or less. <1> The liquid crystal polyester composition according to claim 1. <3> The content of the fatty acid metal salt is 0.001 to 5% by mass with respect to the total mass of the liquid crystal polyester composition. <1> or <2> The liquid crystal polyester composition according to claim 1. <4> The sieve residue of the fatty acid metal salt on a sieve having a nominal mesh size of 250 μm as specified in JIS Z 8801, measured in accordance with JIS K 0069, is 0 to 30% by mass based on the total mass of the fatty acid metal salt. <1> ~ <3> 1. The liquid crystal polyester composition according to claim 1 . <5> The sieve residue of the fatty acid metal salt measured in accordance with JIS K 0069 on a sieve having a nominal mesh size of 180 μm as specified in JIS Z 8801 is 0 to 50% by mass based on the total mass of the fatty acid metal salt. <1> ~ <4> 1. The liquid crystal polyester composition according to claim 1 . <6> The fatty acid metal salt has a melting point of 130 to 300°C. <1> ~ <5> 1. The liquid crystal polyester composition according to claim 1 . <7> The metal of the fatty acid metal salt is calcium or lithium. <1> ~ <6> 1. The liquid crystal polyester composition according to claim 1 . <8> The fatty acid metal salt is calcium laurate or lithium laurate. <7> The liquid crystal polyester composition according to claim 1. <9> The liquid crystal polyester is contained in pellets, At least a portion of the fatty acid metal salt is attached to the surface of the pellet. <1> ~ <8> 1. The liquid crystal polyester composition according to claim 1 . <10> Used as a molding material in injection molding machines with a maximum clamping force of 400 kN or less. <1> ~ <9> 1. The liquid crystal polyester composition according to claim 1 . <11> Used as a molding material in injection molding machines with a screw diameter of 20 mm or less. <1> ~ <10> 1. The liquid crystal polyester composition according to claim 1 . <12> The method includes a mixing step of mixing a liquid crystal polyester and a fatty acid metal salt, The fatty acid metal salt includes a fatty acid metal salt having a fatty acid having 20 or less carbon atoms, the sieve residue of the fatty acid metal salt measured in accordance with JIS K 0069 and having a nominal mesh size of 106 μm as specified in JIS Z 8801 is 0 to 80 mass% based on the total mass of the fatty acid metal salt; The aforementioned <1> ~ <11> 10. A method for producing the liquid crystal polyester composition according to claim 9. <13> The mixing step includes adhering a fatty acid metal salt to the surface of the pellets containing the liquid crystal polyester. <12> 10. A method for producing the liquid crystal polyester composition according to claim 9. <14> The aforementioned <1> ~ <11> 10. A method for producing an injection-molded article, comprising the step of injection-molding the liquid crystal polyester composition according to any one of 9. to 19. to obtain an injection-molded article. <15> The liquid crystal polyester composition is injection-molded using an injection molding machine having a maximum clamping force of 400 kN or less. <14> A method for producing the injection molded article according to claim 1. <16> The liquid crystal polyester composition is injection molded using an injection molding machine having a screw diameter of 20 mm or less. <14> or <15> A method for producing the injection molded article according to claim 1. <17> The liquid crystal polyester composition contains a recycled material of the liquid crystal polyester. <14> ~ <16> 10. A method for producing an injection-molded article according to any one of the preceding items. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a liquid crystal polyester composition that can shorten the plasticization time in injection molding. According to the present invention, a method for producing the liquid crystal polyester composition can be provided. According to the present invention, there can be provided a method for producing an injection-molded article using the liquid crystal polyester composition as a molding material. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a schematic diagram showing a mold for measuring thin-wall flow length used in the examples. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, embodiments of the liquid crystal polyester composition, the method for producing the liquid crystal polyester composition, and the method for producing an injection-molded article of the present invention will be described.

[0013] <Liquid Crystal Polyester Composition> The liquid crystal polyester composition of the embodiment comprises a liquid crystal polyester and a fatty acid metal salt, wherein the fatty acid metal salt comprises a fatty acid metal salt having a fatty acid having 20 or less carbon atoms, and the sieve residue of the fatty acid metal salt measured in accordance with JIS K 0069 on a sieve having a nominal mesh size of 106 μm as specified in JIS Z 8801 is 0 to 80 mass % relative to the total mass (100 mass %) of the fatty acid metal salt in the liquid crystal polyester composition.

[0014] <Fatty acid metal salts> The fatty acid metal salt contained in the liquid crystal polyester composition of the embodiment includes a fatty acid metal salt having a carbon number of 20 or less, preferably a fatty acid metal salt having a carbon number of 2 to 20, more preferably a fatty acid metal salt having a carbon number of 10 to 18, and even more preferably a fatty acid metal salt having a carbon number of 12 to 16. The fatty acid may be a saturated fatty acid or an unsaturated fatty acid. By including a fatty acid metal salt in which the number of carbon atoms in the fatty acid falls within the above range, the plasticization time during injection molding can be shortened.

[0015] In this specification, "plasticization time" refers to the time from the time when the previous injection is completed and the screw rotation (plasticization and metering of the molding material) begins in injection molding until the molding material containing the molten resin to be injected in the next injection molding is filled at the tip of the cylinder in the amount required for the injection volume. Plasticization time is sometimes also called metering time. Plasticization time can be measured using a measuring device attached to the injection molding machine.

[0016] One of the functions of the fatty acid metal salt is to act as a lubricant, which makes it easier for the liquid crystal polyester composition to be delivered to the tip of the cylinder by the screw of the injection molding machine, and is thought to thereby be able to shorten the plasticization time during injection molding.

[0017] The fatty acid metal salt contained in the liquid crystal polyester composition of the embodiment may contain 50 to 100 mass %, 80 to 100 mass %, or 95 to 100 mass % of the fatty acid metal salt having a carbon number of 20 or less relative to the total content (100 mass %) of fatty acid metal salt in the liquid crystal polyester composition.

[0018] Specific examples of fatty acids having 20 or less carbon atoms include lauric acid, tridecylic acid, myristic acid, pentadecylic acid, palmitic acid, margaric acid, stearic acid, nonadecylic acid, and arachidic acid.

[0019] Furthermore, from the viewpoint of the molding processability of the liquid crystal polyester composition, particularly shortening the plasticization time, the fatty acid metal salt preferably has a melting point of 130 to 300°C, more preferably 140 to 280°C, even more preferably 150 to 270°C, and particularly preferably 200 to 260°C. For example, when the liquid crystal polyester composition is in the form of pellets, the pellets may be dried at 100° C. or higher. When the melting point of the fatty acid metal salt is within the above range, the fatty acid metal salt is less likely to melt, decompose, or evaporate due to heat treatment such as drying, and molding processability, particularly the effect of shortening the plasticization time, is improved.

[0020] In this specification, the "melting point" of a fatty acid metal salt refers to the highest endothermic peak temperature observed when measured by differential scanning calorimetry using a differential scanning calorimeter (e.g., DSC-50 manufactured by Shimadzu Corporation) at a temperature rise rate of 20°C / min from room temperature.

[0021] The fatty acid metal salt contained in the liquid crystal polyester composition of the embodiment is preferably a metal salt of lauric acid or stearic acid. Specific examples of the fatty acid metal salt include calcium laurate, calcium stearate, lithium laurate, lithium stearate, barium laurate, barium stearate, aluminum laurate, aluminum stearate, potassium laurate, potassium stearate, sodium laurate, and sodium stearate. Among the above, at least one fatty acid metal salt selected from the group consisting of calcium laurate, calcium stearate, lithium laurate, lithium stearate, barium laurate, and barium stearate is more preferred.

[0022] The metal in the fatty acid metal salt is preferably calcium or lithium. A preferred example of the fatty acid metal salt is at least one fatty acid metal salt selected from the group consisting of calcium laurate, lithium laurate, and lithium stearate.

[0023] The metal of the fatty acid metal salt is preferably lithium, since it has more stable properties under high temperature conditions, such as a high melting point and a small mass loss rate. A preferred specific example of such a fatty acid metal salt is at least one fatty acid metal salt selected from the group consisting of lithium laurate and lithium stearate.

[0024] The mass loss rate of the fatty acid metal salt may be 1 or less, may be 0.1 to 1, or may be 0.2 to 0.6. The mass loss rate of the fatty acid metal salt is calculated by measuring the mass (g) of the fatty acid metal salt before and after heat treatment, which is performed by holding the fatty acid metal salt at 160°C for 48 hours in an air atmosphere and then cooling it to room temperature, and then using the following formula: Mass reduction rate (%) of fatty acid metal salt = (mass (g) of fatty acid metal salt before heat treatment - mass (g) of fatty acid metal salt after heat treatment) ÷ mass (g) of fatty acid metal salt before heat treatment × 100

[0025] Furthermore, the sieve residue of the fatty acid metal salt contained in the liquid crystal polyester composition of the embodiment, measured in accordance with JIS K 0069 and having a nominal mesh size of 106 μm as specified in JIS Z 8801, is 0 to 80 mass%, preferably 0 to 60 mass%, more preferably 0 to 40 mass%, even more preferably 0 to 30 mass%, and particularly preferably 0 to 25 mass%, relative to the total mass content (100 mass%) of the fatty acid metal salt in the liquid crystal polyester composition of the embodiment. A liquid crystalline polyester composition containing a fatty acid metal salt having a sieve residue on a sieve with a nominal mesh size of 106 μm or less is excellent in the effect of shortening the plasticization time during injection molding, and is also excellent in the effect of suppressing variations in peak pressure (maximum injection pressure) during injection molding and stabilizing the injection pressure.

[0026] This is thought to be because the fatty acid metal salt contains fewer particles with a large particle size (sieve residue) based on a mesh size of 106 μm, i.e., more particles with a small particle size (sieve-through portion), which makes it easier to uniformly distribute the fatty acid metal salt and allows the fatty acid metal salt to exert its effects more effectively.

[0027] It is also important to note that the particle size of the fatty acid metal salt is determined by the sieve residue. In general particle size measurements, the particle size is sometimes determined by a value corresponding to the primary particle size, such as when a sample is prepared by dispersing particles in a liquid. However, as shown in the examples below, it has become clear that there is little correlation between the average particle size (corresponding to the primary particle size) determined by microscopic observation and the plasticization time. In contrast, the value of the sieve residue (corresponding to the secondary particle size, etc.) was found to correlate with the plasticization time, etc., and it was found that the particle size of the fatty acid metal salt using the sieve residue is an important factor in the plasticization time. This is thought to be because the particle size determined by sieving more appropriately reflects the state of the fatty acid metal salt during plasticization (metering) in actual injection molding.

[0028] From a similar viewpoint, the sieve residue of the fatty acid metal salt contained in the liquid crystal polyester composition of the embodiment, measured in accordance with JIS K 0069 and having a nominal mesh size of 250 μm as specified in JIS Z 8801, is preferably 0 to 30 mass%, more preferably 0 to 7 mass%, even more preferably 0 to 5 mass%, and particularly preferably 0 to 3 mass%, relative to the total mass content (100 mass%) of the fatty acid metal salt in the liquid crystal polyester composition of the embodiment.

[0029] From a similar viewpoint, the sieve residue of the fatty acid metal salt contained in the liquid crystal polyester composition of the embodiment, measured in accordance with JIS K 0069 and having a nominal mesh size of 180 μm as specified in JIS Z 8801, is preferably 0 to 50 mass%, more preferably 0 to 30 mass%, and even more preferably 0 to 20 mass%, relative to the total mass (100 mass%) of the fatty acid metal salt contained in the liquid crystal polyester composition of the embodiment.

[0030] From a similar viewpoint, the sieve residue of the fatty acid metal salt contained in the liquid crystal polyester composition of the embodiment, measured in accordance with JIS K 0069 and having a nominal mesh size of 75 μm as specified in JIS Z 8801, may be 0 to 100 mass%, 10 to 90 mass%, 20 to 80 mass%, or 30 to 70 mass%, relative to the total mass content (100 mass%) of the fatty acid metal salt in the liquid crystal polyester composition of the embodiment.

[0031] The fatty acid metal salt contained in the liquid crystal polyester composition of the embodiment may be a powder of fatty acid metal salt that satisfies the above-mentioned sieve residue requirement.

[0032] The content of the fatty acid metal salt in the liquid crystal polyester composition of the embodiment can be appropriately determined within a range that exhibits the effect of shortening the plasticization time during injection molding. For example, the content of the fatty acid metal salt in the liquid crystal polyester composition is preferably 0.001 to 5 mass%, more preferably 0.002 to 3 mass%, and even more preferably 0.003 to 0.5 mass%, relative to the total mass (100 mass%) of the liquid crystal polyester composition of the embodiment.

[0033] <Liquid Crystal Polyester> Hereinafter, one embodiment of the liquid crystal polyester used in this embodiment will be described.

[0034] The liquid crystal polyester according to this embodiment is a polyester that exhibits liquid crystallinity in a molten state, and is preferably one that melts at a temperature of 450°C or less. The liquid crystal polyester may be a liquid crystal polyester amide, a liquid crystal polyester ether, a liquid crystal polyester carbonate, or a liquid crystal polyester imide. The liquid crystal polyester is preferably a wholly aromatic liquid crystal polyester that has only structural units derived from aromatic compounds as raw material monomers.

[0035] Typical examples of liquid crystal polyesters include polymers obtained by polycondensation of an aromatic hydroxycarboxylic acid, an aromatic dicarboxylic acid, and at least one compound selected from the group consisting of an aromatic diol, an aromatic hydroxyamine, and an aromatic diamine; polymers obtained by polymerizing a plurality of aromatic hydroxycarboxylic acids; polymers obtained by polymerizing an aromatic dicarboxylic acid and at least one compound selected from the group consisting of an aromatic diol, an aromatic hydroxyamine, and an aromatic diamine; and polymers obtained by polymerizing a polyester such as polyethylene terephthalate with an aromatic hydroxycarboxylic acid.

[0036] Among these, the liquid crystal polyester is preferably a polymer obtained by condensation polymerization (polycondensation) of an aromatic hydroxycarboxylic acid, an aromatic dicarboxylic acid, and at least one compound selected from the group consisting of an aromatic diol, an aromatic hydroxyamine, and an aromatic diamine.

[0037] Here, the aromatic hydroxycarboxylic acid, aromatic dicarboxylic acid, aromatic diol, aromatic hydroxyamine and aromatic diamine may be replaced in part or in whole by their polymerizable ester-forming derivatives, independently of one another.

[0038] Examples of polymerizable derivatives of compounds having a carboxy group, such as aromatic hydroxycarboxylic acids and aromatic dicarboxylic acids, include esters, acid halides, and acid anhydrides. Examples of the esters include compounds obtained by converting the carboxy group to an alkoxycarbonyl group or an aryloxycarbonyl group. Examples of the acid halides include compounds obtained by converting the carboxy group to a haloformyl group. Examples of the acid anhydrides include compounds obtained by converting the carboxy group to an acyloxycarbonyl group.

[0039] Examples of polymerizable derivatives of compounds having a hydroxy group, such as aromatic hydroxycarboxylic acids, aromatic diols, and aromatic hydroxyamines, include those obtained by acylation of the hydroxy group to convert it into an acyloxy group (acylated products). Examples of polymerizable derivatives of compounds having an amino group, such as aromatic hydroxyamines and aromatic diamines, include compounds obtained by acylation of the amino group to convert it into an acylamino group (acylated products).

[0040] Among the examples of the polymerizable derivatives given above, acylated products obtained by acylation of aromatic hydroxycarboxylic acids and aromatic diols are preferred as raw material monomers for liquid crystal polyesters.

[0041] The liquid crystal polyester according to this embodiment preferably has a structural unit represented by the following formula (1) (hereinafter, sometimes referred to as "structural unit (1)"). (1)-O-Ar1-CO- (Ar1 represents a divalent aromatic hydrocarbon group, One or more hydrogen atoms in the group represented by Ar1 may be substituted, independently of one another, with a halogen atom, an alkyl group having 1 to 10 carbon atoms, or an aryl group having 6 to 20 carbon atoms.

[0042] In the liquid crystal polyester according to the embodiment, in the structural unit represented by the following formula (1), Ar1 preferably represents a phenylene group, a naphthylene group, or a biphenylylene group. The liquid crystal polyester according to the embodiment more preferably has the structural unit (1), a structural unit represented by the following formula (2) (hereinafter sometimes referred to as "structural unit (2)"), and a structural unit represented by the following formula (3) (hereinafter sometimes referred to as "structural unit (3)").

[0043] (1)-O-Ar1-CO- (2)-CO-Ar2-CO- (3)-X-Ar3-Y-

[0044] [In the formulas (1) to (3), Ar1 represents a phenylene group, a naphthylene group, or a biphenylylene group.] Ar2 and Ar3 each independently represent a phenylene group, a naphthylene group, a biphenylylene group, or a group represented by the following formula (4): X and Y each independently represent an oxygen atom or an imino group (-NH-). One or more hydrogen atoms in the groups represented by Ar1, Ar2, or Ar3 may be substituted, independently of one another, with a halogen atom, an alkyl group having 1 to 10 carbon atoms, or an aryl group having 6 to 20 carbon atoms.]

[0045] (4)-Ar4-Z-Ar5-

[0046] In formula (4), Ar4 and Ar5 each independently represent a phenylene group or a naphthylene group, and Z represents an oxygen atom, a sulfur atom, a carbonyl group, a sulfonyl group, or an alkylidene group having 1 to 10 carbon atoms. One or more hydrogen atoms in the group represented by Ar4 or Ar5 may be substituted, independently of one another, with a halogen atom, an alkyl group having 1 to 10 carbon atoms, or an aryl group having 6 to 20 carbon atoms.]

[0047] In the structural unit (3), X and Y are preferably oxygen atoms.

[0048] The halogen atoms that can replace the hydrogen atoms include fluorine atoms, chlorine atoms, bromine atoms, and iodine atoms.

[0049] Examples of the alkyl group having 1 to 10 carbon atoms that can replace a hydrogen atom include a methyl group, an ethyl group, a 1-propyl group, an isopropyl group, a 1-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a 1-hexyl group, a 2-ethylhexyl group, a 1-octyl group, and a 1-decyl group.

[0050] Examples of the aryl group having 6 to 20 carbon atoms that can be substituted for a hydrogen atom include monocyclic aromatic groups such as a phenyl group, an orthotolyl group, a metatolyl group, and a paratolyl group, and condensed ring aromatic groups such as a 1-naphthyl group and a 2-naphthyl group.

[0051] When one or more hydrogen atoms in the group represented by Ar1, Ar2, Ar3, Ar4, or Ar5 are substituted with the halogen atom, the alkyl group having 1 to 10 carbon atoms, or the aryl group having 6 to 20 carbon atoms, the number of groups substituting the hydrogen atoms is preferably 1 or 2, and more preferably 1, for each group represented by Ar1, Ar2, Ar3, Ar4, or Ar5, independently of one another.

[0052] Examples of the alkylidene group having 1 to 10 carbon atoms include a methylene group, an ethylidene group, an isopropylidene group, a 1-butylidene group, and a 2-ethylhexylidene group.

[0053] The liquid crystal polyester according to the embodiment preferably contains a structural unit containing a naphthalene structure. Liquid crystal polyesters containing a structural unit containing a naphthalene structure tend to have excellent dielectric properties.

[0054] The content of the structural unit containing the naphthalene structure in the liquid crystal polyester is preferably 40 mol% or more, more preferably 50 mol% or more, more preferably 55 mol% or more, and even more preferably 60 mol% or more, relative to the total amount of all structural units in the liquid crystal polyester (100 mol% (the mass of each structural unit constituting the liquid crystal polyester is divided by the formula weight of each structural unit to determine the substance equivalent (mol) of each structural unit, and the total value). By having the content of the structural unit containing the naphthalene structure be equal to or more than the above lower limit, it is possible to further reduce the relative dielectric constant of the liquid crystal polyester. The content of the structural unit containing the naphthalene structure in the liquid crystal polyester is preferably 90 mol% or less, more preferably 85 mol% or less, and even more preferably 80 mol% or less, relative to 100 mol% of the total amount of all structural units in the liquid crystal polyester. By keeping the content of the structural unit containing the naphthalene structure below the upper limit, reaction stability can be ensured when producing the liquid crystal polyester. Examples of the numerical range of the content of the structural unit containing the naphthalene structure include 40 mol% or more and 90 mol% or less, 50 mol% or more and 85 mol% or less, 55 mol% or more and 85 mol% or less, and 60 mol% or more and 80 mol% or less.

[0055] In the liquid crystal polyester having the structural unit containing a divalent naphthalene structure, which has the above structural unit (1), the following structural unit (2), and the following structural unit (3), it is preferable that at least one of the multiple Ar1, Ar2, Ar3, Ar4, and Ar5 is a naphthylene group.

[0056] In the liquid crystal polyester according to this embodiment, Ar1 is preferably a 2,6-naphthylene group. Here, the liquid crystal polyester in which Ar1 is a 2,6-naphthylene group preferably has the above structural unit (1), the following structural unit (2), and the following structural unit (3). The liquid crystal polyester according to the embodiment may contain structural units represented by the above formula (1) in which Ar1 is a 2,6-naphthylene group in an amount of 40 mol% or more, 40 mol% to 90 mol%, 50 mol% to 85 mol%, 55 mol% to 85 mol%, or 60 mol% to 80 mol% of the total amount of all structural units in the liquid crystal polyester. do.

[0057] The structural unit (1) is a structural unit derived from an aromatic hydroxycarboxylic acid. Examples of the aromatic hydroxycarboxylic acid include parahydroxybenzoic acid, metahydroxybenzoic acid, 2-hydroxy-6-naphthoic acid, 2-hydroxy-3-naphthoic acid, 1-hydroxy-5-naphthoic acid, 4-hydroxy-4'-carboxydiphenyl ether, and aromatic hydroxycarboxylic acids in which some of the hydrogen atoms on the aromatic ring of these aromatic hydroxycarboxylic acids have been substituted with substituents selected from the group consisting of alkyl groups, aryl groups, and halogen atoms. The aromatic hydroxycarboxylic acids may be used alone or in combination of two or more in the production of the liquid crystal polyester. As the structural unit (1), those in which Ar1 is a 1,4-phenylene group (for example, a structural unit derived from 4-hydroxybenzoic acid) and those in which Ar1 is a 2,6-naphthylene group (for example, a structural unit derived from 6-hydroxy-2-naphthoic acid) are preferred.

[0058] The structural unit (2) is a structural unit derived from an aromatic dicarboxylic acid. Examples of the aromatic dicarboxylic acid include terephthalic acid, isophthalic acid, biphenyl-4,4'-dicarboxylic acid, 2,6-naphthalenedicarboxylic acid, diphenylether-4,4'-dicarboxylic acid, diphenylthioether-4,4'-dicarboxylic acid, and aromatic dicarboxylic acids in which some of the hydrogen atoms on the aromatic rings of these aromatic dicarboxylic acids have been substituted with substituents selected from the group consisting of alkyl groups, aryl groups, and halogen atoms. In producing the liquid crystal polyester, the aromatic dicarboxylic acids may be used alone or in combination of two or more. As the structural unit (2), those in which Ar2 is a 1,4-phenylene group (for example, a structural unit derived from terephthalic acid), those in which Ar2 is a 1,3-phenylene group (for example, a structural unit derived from isophthalic acid), those in which Ar2 is a 2,6-naphthylene group (for example, a structural unit derived from 2,6-naphthalenedicarboxylic acid), and those in which Ar2 is a diphenylether-4,4'-diyl group (for example, a structural unit derived from diphenylether-4,4'-dicarboxylic acid) are preferred.

[0059] The structural unit (3) is a structural unit derived from an aromatic diol, an aromatic hydroxyamine, or an aromatic diamine. Examples of aromatic diols, aromatic hydroxyamines, or aromatic diamines include 4,4'-dihydroxybiphenyl, hydroquinone, methylhydroquinone, resorcinol, 4,4'-dihydroxydiphenyl ketone, 4,4'-dihydroxydiphenyl ether, bis(4-hydroxyphenyl)methane, 1,2-bis(4-hydroxyphenyl)ethane, 4,4'-dihydroxydiphenyl sulfone, 4,4'-dihydroxydiphenyl thioether, 2,6-dihydroxynaphthalene, 1,5-dihydroxynaphthalene, 4-aminophenol, 1,4-phenylenediamine, 4-amino-4'-hydroxybiphenyl, and 4,4'-diaminobiphenyl. The aromatic diol, aromatic hydroxyamine or aromatic diamine may be used alone or in combination of two or more kinds in the production of the liquid crystal polyester. As the structural unit (3), those in which Ar3 is a 1,4-phenylene group (for example, a structural unit derived from hydroquinone, 4-aminophenol, or 1,4-phenylenediamine) and those in which Ar3 is a 4,4'-biphenylylene group (for example, a structural unit derived from 4,4'-dihydroxybiphenyl, 4-amino-4'-hydroxybiphenyl, or 4,4'-diaminobiphenyl) are preferred.

[0060] In this specification, "derived from" means that the chemical structure is changed due to the polymerization of the raw material monomers, and no other structural changes occur.

[0061] In addition, when the liquid crystal polyester film obtained from the liquid composition of the embodiment is required to have particularly good heat resistance, it is preferable that the number of these substituents is small, and it is particularly preferable that it does not have substituents such as alkyl groups.

[0062] Next, examples of liquid crystal polyesters that are particularly suitable for use in the liquid composition of the embodiment will be given below. Specific examples of preferred liquid crystal polyesters include copolymers comprising structural units derived from the following combinations of monomers:

[0063] 1) 4-Hydroxybenzoic acid / 2-hydroxy-6-naphthoic acid copolymer 2) 4-Hydroxybenzoic acid / terephthalic acid / 4,4'-dihydroxybiphenyl copolymer 3) 4-Hydroxybenzoic acid / terephthalic acid / isophthalic acid / 4,4'-dihydroxybiphenyl copolymer 4) 4-Hydroxybenzoic acid / terephthalic acid / isophthalic acid / 4,4'-dihydroxybiphenyl / hydroquinone copolymer 5) 4-hydroxybenzoic acid / terephthalic acid / hydroquinone copolymer 6) 2-Hydroxy-6-naphthoic acid / terephthalic acid / hydroquinone copolymer 7) 2-Hydroxy-6-naphthoic acid / terephthalic acid / 2,6-naphthalenedicarboxylic acid / hydroquinone copolymer 8) 4-Hydroxybenzoic acid / 2-hydroxy-6-naphthoic acid / terephthalic acid copolymer 9) 4-Hydroxybenzoic acid / 2-hydroxy-6-naphthoic acid / isophthalic acid copolymer 10) 4-Hydroxybenzoic acid / 2-hydroxy-6-naphthoic acid / terephthalic acid / 4,4'-dihydroxybiphenyl copolymer 11) 4-Hydroxybenzoic acid / 2-hydroxy-6-naphthoic acid / terephthalic acid / 2,6-naphthalenedicarboxylic acid / 4,4'-dihydroxybiphenyl copolymer 12) 4-Hydroxybenzoic acid / 2-hydroxy-6-naphthoic acid / terephthalic acid / 4,4'-dihydroxybiphenyl / methylhydroquinone copolymer 13) 2-Hydroxy-6-naphthoic acid / terephthalic acid / 4,4'-dihydroxybiphenyl copolymer 14) 2-Hydroxy-6-naphthoic acid / terephthalic acid / isophthalic acid / 4,4'-dihydroxybiphenyl copolymer 15) 2-Hydroxy-6-naphthoic acid / terephthalic acid / 2,6-naphthalenedicarboxylic acid / 4,4'-dihydroxybiphenyl copolymer 16) 2-Hydroxy-6-naphthoic acid / terephthalic acid / isophthalic acid / 2,6-naphthalenedicarboxylic acid / 4,4'-dihydroxybiphenyl copolymer 17) 4-Hydroxybenzoic acid / 2-hydroxy-6-naphthoic acid / terephthalic acid / hydroquinone copolymer 18) 4-Hydroxybenzoic acid / 2-hydroxy-6-naphthoic acid / terephthalic acid / 3,3'-dimethyl-1,1'-biphenyl-4,4'-diol copolymer 19) 4-Hydroxybenzoic Acid / 2-Hydroxy-6-naphthoic Acid / Terephthalic Acid / Hydroquinone / 4,4'-Dihydroxybiphenyl Copolymer 20) 4-Hydroxybenzoic acid / 2,6-naphthalenedicarboxylic acid / 4,4'-dihydroxybiphenyl copolymer 21) 4-Hydroxybenzoic acid / Terephthalic acid / 2,6-Naphthalenedicarboxylic acid / Hydroquinone copolymer 22) 4-Hydroxybenzoic acid / 2,6-naphthalenedicarboxylic acid / hydroquinone copolymer Combine 23) 4-Hydroxybenzoic acid / 2-hydroxy-6-naphthoic acid / 2,6-naphthalenedicarboxylic acid / hydroquinone copolymer 24) 4-Hydroxybenzoic acid / terephthalic acid / 2,6-naphthalenedicarboxylic acid / hydroquinone / 4,4'-dihydroxybiphenyl copolymer 25) 4-Hydroxybenzoic Acid / Terephthalic Acid / 4-Aminophenol Copolymer 26) 2-Hydroxy-6-naphthoic Acid / Terephthalic Acid / 4-Aminophenol Copolymer 27) 4-Hydroxybenzoic Acid / 2-Hydroxy-6-naphthoic Acid / Terephthalic Acid / 4-Aminophenol Copolymer 28) 4-Hydroxybenzoic Acid / Terephthalic Acid / 4,4'-Dihydroxybiphenyl / 4-Aminophenol Copolymer 29) 4-Hydroxybenzoic Acid / Terephthalic Acid / Ethylene Glycol Copolymer 30) 4-Hydroxybenzoic acid / terephthalic acid / 4,4'-dihydroxybiphenyl / ethylene glycol copolymer 31) 4-Hydroxybenzoic acid / 2-hydroxy-6-naphthoic acid / terephthalic acid / ethylene glycol copolymer 32) 4-Hydroxybenzoic acid / 2-hydroxy-6-naphthoic acid / terephthalic acid / 4,4'-dihydroxybiphenyl / ethylene glycol copolymer 33) 4-Hydroxybenzoic acid / terephthalic acid / 2,6-naphthalenedicarboxylic acid / 4,4'-dihydroxybiphenyl copolymer.

[0064] The content of the structural unit (1) in the liquid crystal polyester is preferably 30 mol% or more, more preferably 30 to 90 mol%, more preferably 30 to 85 mol%, even more preferably 40 to 75 mol%, particularly preferably 50 to 70 mol%, and particularly preferably 55 to 70 mol%, based on the total amount of all structural units constituting the liquid crystal polyester (the mass of each structural unit constituting the liquid crystal polyester is divided by the formula weight of that structural unit to determine the substance equivalent (mol) of each structural unit, and the sum of these values). When the content of the structural unit (1) in the liquid crystal polyester is 30 mol% or more, the heat resistance and hardness of the molded article obtained using the liquid composition of this embodiment are likely to be improved. Furthermore, when the content of the structural unit (1) is 80 mol% or less, the melt viscosity can be reduced. Therefore, the temperature required for molding the liquid crystal polyester is likely to be lower.

[0065] The content of the structural unit (2) in the liquid crystal polyester is preferably 35 mol % or less, more preferably 10 to 35 mol %, even more preferably 15 to 35 mol %, and particularly preferably 17.5 to 32.5 mol %, based on the total amount of all structural units constituting the liquid crystal polyester.

[0066] The content of the structural unit (3) in the liquid crystal polyester is preferably 35 mol % or less, more preferably 10 to 35 mol %, even more preferably 15 to 35 mol %, and particularly preferably 17.5 to 32.5 mol %, based on the total amount of all structural units constituting the liquid crystal polyester.

[0067] In the liquid crystal polyester, the ratio of the content of the structural unit (2) to the content of the structural unit (3), expressed as [content of the structural unit (2)] / [content of the structural unit (3)] (mol / mol), is preferably 0.9 or more and 1.1 or less, more preferably 0.95 or more and 1.05 or less, and even more preferably 0.98 or more and 1.02 or less.

[0068] In the liquid crystal polyester, the ratio of the content of the structural unit (3) to the content of the structural unit (1), expressed as [content of the structural unit (3)] / [content of the structural unit (1)] (mol / mol), is preferably 0.2 or more and 1.0 or less, more preferably 0.25 or more and 0.85 or less, and even more preferably 0.3 or more and 0.75 or less.

[0069] The liquid crystal polyester may independently have only one type or two or more types of the structural units (1) to (3). The liquid crystal polyester may also have one or more types of structural units other than the structural units (1) to (3), and the content thereof is preferably 10 mol % or less, more preferably 5 mol % or less, based on the total amount of all structural units of the liquid crystal polyester.

[0070] [Liquid crystal polyester mixture] In the present embodiment, a liquid crystal polyester mixture containing a plurality of liquid crystal polyesters can be used. This further improves the melt flowability of the liquid crystal polyester composition of the present embodiment, and can sufficiently suppress warpage of the resulting molded article. Here, the liquid crystalline polyester mixture is assumed to be a mixture of liquid crystalline polyesters with different flow initiation temperatures, in which the one with a higher flow initiation temperature is designated as a first liquid crystalline polyester, and the one with a lower flow initiation temperature is designated as a second liquid crystalline polyester.

[0071] The flow initiation temperature of the first liquid crystal polyester is preferably 300° C. or higher, more preferably 310° C. or higher, and even more preferably 315° C. or higher. The flow initiation temperature of the first liquid crystal polyester is preferably 400° C. or lower, more preferably 360° C. or lower, and even more preferably 345° C. or lower. The upper and lower limits can be combined in any manner.

[0072] When the flow starting temperature of the first liquid crystal polyester is within the above range, it tends to be possible to achieve both melt flowability and heat resistance of the obtained molded article.

[0073] On the other hand, the flow initiation temperature of the second liquid crystal polyester is preferably 260° C. or higher, more preferably 270° C. or higher, and even more preferably 285° C. or higher. The flow initiation temperature of the second liquid crystal polyester is preferably 350° C. or lower, more preferably 320° C. or lower, and even more preferably 315° C. or lower. The upper and lower limits can be combined in any manner.

[0074] When the flow initiation temperature of the second liquid crystal polyester is within the above range, the fluidity of the thin wall portion of the mold (thin wall fluidity) tends to be good, and the deflection temperature under load of the obtained molded article tends to be sufficiently high.

[0075] In addition, in the liquid crystal polyester mixture, the content of the second liquid crystal polyester is preferably 10 to 150 parts by mass, more preferably 30 to 120 parts by mass, and even more preferably 50 to 100 parts by mass, relative to 100 parts by mass of the first liquid crystal polyester.

[0076] The content of the second liquid crystal polyester relative to the first liquid crystal polyester may be appropriately set so that the liquid crystal polyester mixture has a desired balance between the deflection temperature under load and the thin-wall flowability.

[0077] The liquid crystal polyester mixture may contain a liquid crystal polyester other than the first liquid crystal polyester and the second liquid crystal polyester. In this case, the liquid crystal polyester having the highest flow initiation temperature in the mixture may be the first liquid crystal polyester, and the liquid crystal polyester having the lowest flow initiation temperature may be the second liquid crystal polyester. A liquid crystal polyester mixture consisting essentially of the first liquid crystal polyester and the second liquid crystal polyester is preferred.

[0078] In the liquid crystal polyester mixture, α / β is preferably in the range of 0.1 or more and 0.6 or less, and more preferably in the range of 0.3 or more and 0.6 or less. α represents the molar ratio y / x of the first liquid crystal polyester. β represents the molar ratio y / x of the second liquid crystal polyester. x is Ar2 represents the molar content of repeating units that are 1,4-phenylene groups. y is Ar 2 represents the molar content of repeating units that are 1,3-phenylene groups.

[0079] The content of the liquid crystal polyester in the liquid crystal polyester composition of the embodiment is preferably 30 to 99.5 mass%, more preferably 40 to 90 mass%, and even more preferably 50 to 80 mass%, relative to the total mass (100 mass%) of the liquid crystal polyester composition of the embodiment.

[0080] [Method of manufacturing liquid crystal polyester] Next, an example of a method for producing the liquid crystal polyester used in this embodiment will be described.

[0081] The liquid crystal polyester of the present embodiment is preferably produced by the following acylation step and polymerization step.

[0082] The acylation step is a step in which the phenolic hydroxy group of the raw material monomer is acylated with a fatty acid anhydride (for example, acetic anhydride) to obtain an acylated product.

[0083] In the polymerization step, the acyl group of the acylated product obtained in the acylation step and the carbonyl group contained in the carboxyl group of the acylated product of the aromatic dicarboxylic acid and aromatic hydroxycarboxylic acid are polymerized to cause ester exchange, thereby obtaining a liquid crystal polyester.

[0084] The acylation step and the polymerization step may be carried out in the presence of a heterocyclic organic base compound represented by the following formula (5).

[0085] [ka]

[0086] In the above formula (5), R 1 ~R4 each independently represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, a hydroxymethyl group, a cyano group, a cyanoalkyl group in which the alkyl group has 1 to 4 carbon atoms, a cyanoalkoxy group in which the alkoxy group has 1 to 4 carbon atoms, a carboxy group, an amino group, an aminoalkyl group having 1 to 4 carbon atoms, an aminoalkoxy group having 1 to 4 carbon atoms, a phenyl group, a benzyl group, a phenylpropyl group, or a formyl group.

[0087] The heterocyclic organic base compound of the above formula (5) includes R 1 is an alkyl group having 1 to 4 carbon atoms, and R 2 ~R 4 are preferably imidazole derivatives in which each is a hydrogen atom. This can further improve the reactivity of the acylation reaction in the acylation step and the transesterification reaction in the polymerization step.

[0088] Among heterocyclic organic base compounds, either or both of 1-methylimidazole and 1-ethylimidazole are particularly preferred because they are easily available.

[0089] The amount of the heterocyclic organic base compound used is preferably 0.005 to 1 part by mass when the total amount of raw material monomers (i.e., aromatic dicarboxylic acid, aromatic diol, aromatic hydroxycarboxylic acid, etc.) of the liquid crystal polyester is 100 parts by mass. From the viewpoint of productivity of the molded article, the amount is more preferably 0.05 to 0.5 parts by mass per 100 parts by mass of the raw material monomers.

[0090] The heterocyclic organic base compound may be added at any time during the acylation reaction and the transesterification reaction, and may be added immediately before the start of the acylation reaction, during the acylation reaction, or between the acylation reaction and the transesterification reaction. The liquid crystal polyester thus obtained has very high melt fluidity and excellent thermal stability.

[0091] The amount of fatty acid anhydride (e.g., acetic anhydride) used should be determined taking into consideration the amounts of aromatic diol and aromatic hydroxycarboxylic acid used as raw material monomers. Specifically, the amount is preferably 1.0 to 1.2 equivalents, more preferably 1.0 to 1.15 equivalents, even more preferably 1.03 to 1.12 equivalents, and particularly preferably 1.05 to 1.1 equivalents, relative to the total amount of phenolic hydroxy groups contained in these raw material monomers.

[0092] When the amount of fatty acid anhydride used is 1.0 equivalent or more relative to the total phenolic hydroxy groups contained in the raw material monomers, the acylation reaction proceeds easily, and unreacted raw material monomers are less likely to remain in the subsequent polymerization step, resulting in efficient polymerization. Furthermore, if the acylation reaction proceeds sufficiently in this manner, the unacylated raw material monomers are less likely to sublimate and clog the fractionator used during polymerization. On the other hand, when the amount of fatty acid anhydride used is 1.2 equivalents or less, the resulting liquid crystal polyester is less likely to be discolored.

[0093] The acylation reaction in the above-mentioned acylation step is preferably carried out at a temperature range of 130°C to 180°C for 30 minutes to 20 hours, more preferably at 140°C to 160°C for 1 to 5 hours.

[0094] The aromatic dicarboxylic acid used in the polymerization step may be present in the reaction system during the acylation step. That is, in the acylation step, the aromatic diol, aromatic hydroxycarboxylic acid, and aromatic dicarboxylic acid may be present in the same reaction system. This is because the carboxy group and any optional substituents in the aromatic dicarboxylic acid are not affected by the fatty acid anhydride.

[0095] Therefore, a method may be used in which an aromatic diol, an aromatic hydroxycarboxylic acid, and an aromatic dicarboxylic acid are charged into a reactor, and then the acylation step and the polymerization step are carried out in that order, or a method may be used in which an aromatic diol and an aromatic dicarboxylic acid are charged into a reactor, and then the acylation step is carried out, and then the aromatic dicarboxylic acid is further charged into the reactor, and then the polymerization step is carried out. From the viewpoint of simplifying the production process, the former method is preferred.

[0096] The transesterification reaction in the above-mentioned polymerization step is preferably carried out while increasing the temperature from 130°C to 400°C at a rate of 0.1 to 50°C / min, and more preferably from 150°C to 350°C at a rate of 0.3 to 5°C / min.

[0097] Furthermore, when the transesterification reaction in the polymerization step is carried out, it is preferable to evaporate and remove by-produced fatty acids (e.g., acetic acid) and unreacted fatty acid anhydrides (e.g., acetic anhydride) from the system in order to shift the equilibrium. At this time, by refluxing a portion of the distilled fatty acids and returning them to the reactor, raw material monomers and the like that evaporate or sublimate together with the fatty acids can be condensed or desublimated and returned to the reactor.

[0098] In the acylation reaction in the acylation step and the transesterification reaction in the polymerization step, a batch reactor or a continuous reactor may be used as a reactor. Either reactor can be used to obtain a liquid crystalline polyester that can be used in the present embodiment.

[0099] After the above-mentioned polymerization step, a step for increasing the molecular weight of the liquid crystal polyester obtained in this polymerization step may be carried out. For example, the liquid crystal polyester obtained in the polymerization step is cooled and then pulverized to prepare a powdered liquid crystal polyester, and the powder is further heated, whereby the molecular weight of the liquid crystal polyester can be increased.

[0100] Alternatively, the powdered liquid crystal polyester resin obtained by cooling and pulverization may be granulated to prepare pelletized liquid crystal polyester, and then the pelletized liquid crystal polyester may be heated to increase the molecular weight of the liquid crystal polyester. In the technical field, the increase in molecular weight using these methods is called solid-state polymerization.

[0101] Solid-phase polymerization is particularly effective as a method for increasing the molecular weight of liquid crystal polyester. By increasing the molecular weight of the liquid crystal polyester, it becomes easier to obtain a liquid crystal polyester having a suitable flow initiation temperature as described below.

[0102] The reaction conditions for the solid-state polymerization are usually such that the solid-state liquid crystalline polyester is heat-treated for 1 to 20 hours under an inert gas atmosphere or under reduced pressure.The polymerization conditions for this solid-state polymerization can be appropriately optimized after determining the flow initiation temperature of the liquid crystalline polyester obtained by the melt polymerization.In addition, the apparatus used for this heat treatment can be, for example, a known dryer, a reactor, an inert oven, or an electric furnace.

[0103] The flow initiation temperature of the liquid crystal polyester is preferably 270°C or higher, more preferably 270 to 400°C, and even more preferably 280 to 380°C. When a liquid crystal polyester having a flow initiation temperature in this range is used, the heat resistance of a molded article obtained using the liquid crystal polyester composition of this embodiment can be improved. Furthermore, during melt molding to obtain a molded article from the liquid crystal polyester composition, the thermal stability of the liquid crystal polyester is improved, and thermal degradation can be avoided.

[0104] The flow initiation temperature, also called the flow temperature or fluidity temperature, is the temperature at which a liquid crystalline polyester melt is extruded from a nozzle with an inner diameter of 1 mm and a length of 10 mm under a load of 9.8 MPa at a rate of 4°C / min using a capillary rheometer, and exhibits a viscosity of 4800 Pa s (48,000 poises). This temperature is an indicator of the molecular weight of the liquid crystalline polyester (see, for example, "Liquid Crystal Polymer - Synthesis, Molding, and Applications" edited by Naoyuki Koide, pp. 95-105, CMC, published June 5, 1987).

[0105] The liquid crystalline polyester having the above-mentioned suitable flow initiation temperature can be easily obtained by appropriately optimizing the structural units constituting the liquid crystalline polyester. That is, when the linearity of the molecular chain of the liquid crystalline polyester is improved, the flow initiation temperature tends to increase.

[0106] For example, structural units derived from terephthalic acid improve the linearity of the liquid crystalline polyester molecular chain. On the other hand, structural units derived from isophthalic acid improve the flexibility (decreases the linearity) of the liquid crystalline polyester molecular chain. Therefore, by controlling the copolymerization ratio of terephthalic acid and isophthalic acid, a liquid crystalline polyester with a desired flow initiation temperature can be obtained.

[0107] When the liquid crystal polyester mixture is used, at least one liquid crystal polyester is preferably a polymer obtained by polymerizing a raw material monomer containing an aromatic hydroxycarboxylic acid in the presence of an imidazole compound. The liquid crystal polyester thus obtained has very high melt flowability and excellent thermal stability.

[0108] In addition, in the liquid crystal polyester used in this embodiment, it is preferable to optimize the copolymerization ratio of terephthalic acid and isophthalic acid. This allows the linearity of the molecular chain of the liquid crystal polyester to be controlled as described above. As a result, multiple types of liquid crystal polyesters with different flow initiation temperatures can be produced.

[0109] <Other ingredients> The liquid crystal polyester composition may contain one or more other components such as inorganic fillers, organic fillers, additives, and resins other than liquid crystal polyesters, as long as the effects of the present invention are achieved. Hereinafter, "resins other than liquid crystal polyesters" may be referred to as "other resins."

[0110] [Inorganic filler] When the liquid crystal polyester composition of this embodiment contains an inorganic filler, the content of the inorganic filler is preferably more than 0 parts by mass and not more than 100 parts by mass, more preferably 5 parts by mass or more and not more than 100 parts by mass, even more preferably 20 parts by mass or more and not more than 90 parts by mass, and particularly preferably 30 parts by mass or more and not more than 85 parts by mass, relative to 100 parts by mass of the liquid crystal polyester.

[0111] The inorganic filler may be a fibrous filler, a plate-like filler, or a granular filler.

[0112] Examples of fibrous fillers include glass fibers; carbon fibers such as bread-based carbon fibers and pitch-based carbon fibers; ceramic fibers such as silica fibers, alumina fibers, and silica-alumina fibers; and metal fibers such as stainless steel fibers. Other examples include whiskers such as potassium titanate whiskers, barium titanate whiskers, wollastonite whiskers, aluminum borate whiskers, silicon nitride whiskers, and silicon carbide whiskers. Among these, glass fibers are preferred.

[0113] Examples of the plate-like filler include talc, mica, graphite, wollastonite, glass flakes, barium sulfate, and calcium carbonate. Mica may be muscovite, phlogopite, fluorophlogopite, or tetrasilicic mica. Among these, talc or mica is preferred.

[0114] Examples of particulate fillers include silica, alumina, titanium oxide, glass beads, glass balloons, boron nitride, silicon carbide, and calcium carbonate.

[0115] The inorganic filler is preferably at least one selected from the group consisting of glass fiber, talc, and mica.

[0116] (glass fiber) Examples of glass fibers include those produced by various methods, such as chopped glass fibers of long fiber type and milled glass fibers of short fiber type. In this embodiment, two or more of these may be used in combination.

[0117] Examples of the glass fiber include E-glass, A-glass, C-glass, D-glass, AR-glass, R-glass, S-glass, and mixtures thereof. Among these, E-glass is preferred because it has excellent strength and is easily available.

[0118] As the glass fiber, weakly alkaline fibers are preferred because they have excellent mechanical strength (tensile strength and Izod impact strength). In particular, glass fibers having a silicon oxide content of 50% by mass to 80% by mass, and more preferably 65% by mass to 77% by mass, based on the total mass of the glass fiber, are preferred.

[0119] The glass fibers may be fibers treated with a coupling agent such as a silane coupling agent or a titanium coupling agent, if necessary.

[0120] The glass fibers may be coated with a thermoplastic resin such as a urethane resin, an acrylic resin, or an ethylene / vinyl acetate copolymer, or a thermosetting resin such as an epoxy resin, or may be treated with a sizing agent.

[0121] The number-average fiber length of the glass fibers used as the raw material for melt-kneading is preferably 50 μm or more and 3500 μm or less. When the number-average fiber length of the glass fibers is 50 μm or more, the effect as a reinforcing material in a molded article obtained from pellets containing the glass fibers is more improved than when the number-average fiber length is less than 50 μm. The number-average fiber length of the glass fibers is more preferably 60 μm or more, and even more preferably 70 μm.

[0122] Furthermore, when the number average fiber length of the glass fibers is 3,500 μm or less, it is easier to adjust the number average fiber length of the glass fibers in the pellets than when the number average fiber length exceeds 300 μm, and thin-wall flowability is further improved. The number average fiber length of the glass fibers is more preferably 3,000 μm or less.

[0123] The fiber diameter (single fiber diameter) of the glass fiber, which is a raw material to be subjected to melt kneading, is preferably 5 μm or more and 20 μm or less. When the fiber diameter of the glass fiber is 5 μm or more, the reinforcing effect on the molded article can be enhanced compared to when the fiber diameter is less than 5 μm. The fiber diameter of the glass fiber is more preferably 6 μm or more. Furthermore, when the fiber diameter of the glass fiber is 20 μm or less, the fluidity of the liquid crystal polyester composition is improved compared to when the fiber diameter exceeds 20 μm, and further, the effect of the glass fiber as a reinforcing material for the molded article is further enhanced. The fiber diameter of the glass fiber is more preferably 17 μm or less, and more preferably 15 μm or less.

[0124] The diameter of the glass fibers does not change substantially even after melt-kneading.

[0125] In this specification, unless otherwise specified, the "number average fiber length of the raw glass fiber" means the value measured by the method described in JIS R3420 "7.8 Length of chopped strands."

[0126] Furthermore, unless otherwise specified, the "fiber diameter of the glass fiber as the raw material" refers to the value measured by "Method A" among the methods described in JIS R3420 "7.6 Single Fiber Diameter."

[0127] The content of the glass fiber is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, and even more preferably 15 parts by mass or more, relative to 100 parts by mass of the liquid crystal polyester. The content of the glass fiber is preferably 100 parts by mass or less, more preferably 80 parts by mass or less, and even more preferably 60 parts by mass or less, relative to 100 parts by mass of the liquid crystal polyester. The upper and lower limits can be combined in any manner. For example, the content of the glass fiber is preferably 5 parts by mass or more and 100 parts by mass or less, more preferably 10 parts by mass or more and 80 parts by mass or less, and even more preferably 15 parts by mass or more and 60 parts by mass or less, relative to 100 parts by mass of the liquid crystal polyester.

[0128] The number average fiber length of the glass fibers in the pellets of this embodiment is preferably 30 μm or more, more preferably 50 μm or more, and even more preferably 60 μm or more, while from the viewpoint of improving the fluidity of the liquid crystal polyester composition, it is preferably 300 μm or less, more preferably 200 μm or less, and even more preferably 150 μm or less. That is, the number average fiber length of the glass fibers in the pellets of this embodiment is preferably 30 μm or more and 300 μm or less, more preferably 50 μm or more and 200 μm or less, and even more preferably 60 μm or more and 150 μm or less.

[0129] Here, the number average fiber length of the glass fibers in the pellets can be measured by the following method. 5 g of pellets were heated in air in a muffle furnace at 600°C for 8 hours to remove the resin, and 500 or more glass fibers were randomly selected from the remaining glass fibers using a video microscope (Keyence VH1000), and the fiber lengths of the selected glass fibers were measured at 100x magnification. Here, the number average fiber length Ln can be calculated using the following formula: Ln = Σ(Ni × Li) / Σ(Ni)

[0130] Li is the measured fiber length of the glass fiber. Ni is the number of glass fibers with fiber length Li divided by the total number of glass fibers measured.

[0131] (talc) Talc is a pulverized mineral composed of magnesium hydroxide and silicate mineral. The talc used in this embodiment has a structure in which an octahedral structure composed of three magnesium (Mg) oxide-hydroxide atoms is sandwiched between four tetrahedral structures formed by four silicon (Si) oxide atoms.

[0132] The talc used in this embodiment can be produced by known production methods, such as dry pulverization methods, such as a grinding-type pulverization method using a roller mill, a Raymond mill, or the like, an impact pulverization method using an atomizer, a hammer mill, a micron mill, or the like, and a collision pulverization method using a jet mill, a ball mill, or the like.

[0133] Alternatively, a wet grinding method may be used in which ground talc powder is dispersed in water to form a slurry having a flowable viscosity, and the slurry is ground using a ball mill, a bead mill, a wet jet mill, a Discoplex, etc. Among the above production methods, the dry grinding method is preferred from the viewpoints of low cost and easy availability.

[0134] The surface of the talc may be treated with a coupling agent or the like to improve the wettability of the talc with the liquid crystal polyester. Furthermore, talc that has been heat-treated may be used to remove impurities and harden the talc. Furthermore, compressed talc may be used to facilitate handling.

[0135] The 45 μm sieve residue of the talc is preferably 1.0 mass% or less. When the 45 μm sieve residue is 1.0 mass% or less, clogging of the thin-walled portion of the mold can be suppressed when molding the pellets of this embodiment, improving moldability and the thin-wall strength of the resulting molded body. The 45 μm sieve residue contained in the talc is preferably 0.8 mass% or less, more preferably 0.6 mass% or less, based on the total amount of talc.

[0136] In this specification, the 45 μm sieve residue of talc is a value measured in accordance with JIS K 5101-14-1 "Test methods for pigments - Part 14: Sieve residue - Section 1: Wet method (manual method)".

[0137] The talc preferably has an ignition loss (Ig.Loss) of 7% by mass or less, more preferably 6% by mass or less, and particularly preferably 5% by mass or less. The lower the Ig.Loss, the more the decomposition of the liquid crystal polyester is suppressed, and the less likely blisters are to occur. In the present invention, the Ig.Loss is a value measured in accordance with JIS M8853.

[0138] In this embodiment, the volume average particle size of the talc is preferably 5.0 μm or more, more preferably 5.5 μm or more, and even more preferably 6.0 μm or more. The volume average particle size is preferably 25 μm or less, more preferably 24.5 μm or less, and even more preferably 24 μm or less. The upper and lower limits can be combined in any way. For example, the volume average particle size of the talc is preferably 5.0 μm or more and 25 μm or less, more preferably 5.5 μm or more and 24.5 μm or less, and even more preferably 6.0 μm or more and 24 μm or less.

[0139] In this embodiment, the volume average particle size of talc can be measured by a laser diffraction method. Using a scattering particle size distribution analyzer (e.g., HORIBA Corporation's "LA-950V2") as a measuring device, the volume average particle size can be calculated under the following measuring conditions when the talc is dispersed in water.

[0140] (Measurement conditions) Particle refractive index: 1.59-0.1i Dispersion medium: water Dispersion medium refractive index: 1.33

[0141] In the present embodiment, the content of talc is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, and particularly preferably 30 parts by mass or more, relative to 100 parts by mass of the liquid crystal polyester, and is preferably 100 parts by mass or less, more preferably 80 parts by mass or less, and particularly preferably 65 parts by mass or less, relative to 100 parts by mass of the liquid crystal polyester. The above upper and lower limits can be combined in any desired manner. For example, the content of talc is preferably 5 to 100 parts by mass, more preferably 10 to 80 parts by mass, particularly preferably 30 to 65 parts by mass, relative to 100 parts by mass of the liquid crystal polyester.

[0142] (mica) Mica is a crushed silicate mineral containing aluminum, potassium, magnesium, sodium, iron, etc. Mica is a mineral with a structure in which an octahedral structure made up of two or three metal oxides or hydroxides is sandwiched between four tetrahedral structures made up of oxides of three silicon (Si) atoms and one aluminum (Al) atom.

[0143] The mica used in this embodiment may be any of muscovite, phlogopite, fluorphlogopite, tetrasilicic mica, and artificially produced synthetic mica, and may contain two or more types of these.

[0144] The mica used in this embodiment preferably consists essentially of muscovite mica.

[0145] Examples of methods for producing the mica used in this embodiment include water jet pulverization, wet pulverization, dry ball mill pulverization, pressure roller mill pulverization, air jet mill pulverization, and dry pulverization using an impact pulverizer such as an atomizer. It is preferable to use mica produced by a wet pulverization method, as this allows the mica to be pulverized into thin, fine particles.

[0146] When wet milling is used, mica before milling is dispersed in water. To improve the dispersion efficiency of the mica before milling, additives such as flocculating and settling agents and sedimentation aids, such as polyaluminum chloride, aluminum sulfate, aluminum sulfate, ferrous sulfate, ferric sulfate, copper chloride, polyferric sulfate, polyferric chloride, iron-silica inorganic polymer flocculant, ferric chloride-silica inorganic polymer flocculant, hydrated lime (Ca(OH)), caustic soda (NaOH), and soda ash (NaCO), are typically added. However, these additives may cause decomposition of the liquid crystalline polyester. Therefore, the mica used in this embodiment is preferably one that has not been wet milled using flocculating and settling agents and sedimentation aids.

[0147] In this embodiment, the volume average particle size of the mica is preferably 20 μm or more, more preferably 21 μm or more, and particularly preferably 22 μm or more. The volume average particle size is preferably 45 μm or less, more preferably 44 μm or less, and particularly preferably 43 μm or less. The upper and lower limits can be combined in any way. For example, the volume average particle size of the mica is preferably 20 μm or more and 45 μm or less, more preferably 21 μm or more and 44 μm or less, and particularly preferably 22 μm or more and 43 μm or less.

[0148] In this embodiment, the volume average particle size of mica can be measured by laser diffraction. A scattering type particle size distribution analyzer (e.g., HORIBA Corporation's "LA-950V2") is used as the measuring device, and the volume average particle size can be calculated under the following measurement conditions with mica dispersed in water.

[0149] (Measurement conditions) Particle refractive index: 1.57-0.1i Dispersion medium: water Dispersion medium refractive index: 1.33

[0150] Mica having such a volume average particle size has good miscibility with the liquid crystal polyester, and can further improve the fluidity of the liquid crystal polyester composition of this embodiment.

[0151] The mica content is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, and even more preferably 30 parts by mass or more, relative to 100 parts by mass of the liquid crystal polyester. The mica content is preferably 100 parts by mass or less, more preferably 85 parts by mass or less, even more preferably 65 parts by mass or less, and particularly preferably 20 parts by mass or less, relative to 100 parts by mass of the liquid crystal polyester. The upper and lower limits can be combined in any manner. For example, the content of mica is preferably 5 to 100 parts by mass, more preferably 10 to 85 parts by mass, and even more preferably 30 to 65 parts by mass, relative to 100 parts by mass of the liquid crystal polyester.

[0152] A liquid crystal polyester composition having a mica content within this range provides a molded article with good heat resistance.

[0153] [Organic filler] When the liquid crystal polyester composition of this embodiment contains an organic filler, the content of the organic filler in the liquid crystal polyester composition is preferably more than 0 parts by mass and not more than 100 parts by mass per 100 parts by mass of the total content of the liquid crystal polyester.

[0154] The organic filler used in this embodiment may be a fibrous filler, a plate-like filler, or a granular filler. Examples of fibrous fillers include polyester fibers, aramid fibers, and cellulose fibers. Examples of particulate fillers include insoluble and infusible polymers such as homopolymers of parahydroxybenzoic acid.

[0155] [Additives] When the liquid crystal polyester composition of the present embodiment contains an additive, the content of the additive in the liquid crystal polyester composition is preferably more than 0 parts by mass and not more than 5 parts by mass relative to 100 parts by mass of the total content of the liquid crystal polyester.

[0156] Examples of additives include, for example, additives known in the art.

[0157] Examples of additives well known in the art include release agents such as higher fatty acid esters and metal soaps, colorants such as dyes and pigments, antioxidants, heat stabilizers, ultraviolet absorbers, antistatic agents, surfactants, flame retardants, flame retardant assistants, and plasticizers. Further, examples of the additives include additives having an external lubricant effect, such as higher fatty acids, higher fatty acid esters, and fluorocarbon surfactants. The type and amount of these additives to be used are determined within a range that does not impair the effects of the present invention. The content of the additive is preferably 0.01 to 5 parts by mass relative to 100 parts by mass of the liquid crystal polyester.

[0158] (carbon black) In this embodiment, it is preferable to use carbon black as the colorant.

[0159] Examples of carbon black used in this embodiment include channel black, furnace black, lamp black, thermal black, ketjen black, and naphthalene black, and two or more of these may be used. Among these, furnace black and lamp black are particularly preferred, but any commercially available carbon black for coloring can be used as long as it has the desired properties described above. The carbon black content is preferably 0.1 to 2.5 parts by mass, more preferably 0.2 to 2.0 parts by mass, per 100 parts by mass of the liquid crystal polyester.

[0160] (mold release agent) In this embodiment, the liquid crystal polyester composition contains a release agent, which can improve molding processability. Examples of the release agent include tetrafluoroethylene, montanic acid and its salts, its esters, its half esters, stearyl alcohol, stearamide, and polyethylene wax, and preferably tetrafluoroethylene or a fatty acid ester of pentaerythritol.

[0161] The content of the release agent is preferably 0.1 to 1.0 part by mass, and more preferably 0.2 to 0.7 part by mass, relative to 100 parts by mass of the liquid crystal polyester. When the content of the release agent is within the above range, mold contamination and blistering of the molded product tend to be less likely to occur, and a release effect can be obtained.

[0162] (antioxidants, heat stabilizers) In this embodiment, it is preferable to use, as the antioxidant or heat stabilizer, for example, hindered phenol, hydroquinone, phosphites, and substituted derivatives thereof.

[0163] (ultraviolet absorber) In this embodiment, it is preferable to use, for example, resorcinol, salicylate, benzotriazole, benzophenone, or the like as the ultraviolet absorber.

[0164] Examples of other resins include thermoplastic resins other than aromatic polysulfones, such as polypropylene, polyamide, polyesters other than liquid crystal polyester, polyphenylene sulfide, polyether sulfone, polyether ketone, polycarbonate, polyphenylene ether, and polyether imide; and thermosetting resins such as phenolic resin, epoxy resin, polyimide resin, and cyanate resin.

[0165] When the liquid crystal polyester composition of the present embodiment contains other resins, the content of the other resins is preferably more than 0 parts by mass and not more than 20 parts by mass relative to 100 parts by mass of the total content of the liquid crystal polyester.

[0166] (pellet) In the liquid crystal polyester composition, the form of the fatty acid metal salt is not particularly limited. The liquid crystal polyester composition of the embodiment is a concept that includes pellets containing the liquid crystal polyester. In this case, the fatty acid metal salt may be present inside the pellet, or may be present outside, including on the surface of the pellet, or may be present both inside and outside the pellet.

[0167] The liquid crystal polyester composition of the embodiment preferably contains pellets containing the liquid crystal polyester, and at least a portion of the fatty acid metal salt is attached to the surface of the pellets.

[0168] That is, the liquid crystal polyester composition of the embodiment may be a pellet of the liquid crystal polyester composition, and the fatty acid metal salt may be attached to the surface of the pellet, or the fatty acid metal salt may be attached in solid form to the surface of the pellet, or the fatty acid metal salt may be attached in powder form to the surface of the pellet.

[0169] The pellets are suitable as molding materials for injection molding. It is believed that the fatty acid metal salt adheres to the pellet surface, thereby more effectively acting as a lubricant. This makes it easier for the pellets to be delivered by the screw of an injection molding machine, which is believed to shorten the plasticization time during injection molding.

[0170] The length and shape of the pellets of this embodiment are not particularly limited and can be selected arbitrarily depending on the purpose.

[0171] The length of the pellet is preferably 2 mm or more and 4 mm or less, and more preferably 2.5 mm or more and 4 mm or less.

[0172] The pellets of this embodiment can be obtained, for example, by extruding the liquid crystal polyester composition in the form of strands from an extruder or the like, and cutting the strands with a cutter having a rotary blade.

[0173] The shape of the pellets may be spherical, rectangular, spheroidal, slightly deformed from an exact spheroid, cylindrical, etc. Among these, the pellet shape is preferably a cylindrical pellet with a substantially elliptical cross section.

[0174] In the pellets of this embodiment, the major axis of the cross section of the pellet is not particularly limited, but is preferably 1 mm or more and 5 mm or less, more preferably 2 mm or more and 4 mm or less, and even more preferably 2 mm or more and 3.5 mm or less. In the pellets of this embodiment, the minor axis of the cross section of the pellet is not particularly limited, but is preferably 1 mm or more and 5 mm or less, and more preferably 2 mm or more and 3 mm or less. The ratio of the major axis to the minor axis of the cut surface of the pellet (major axis / minor axis) is not particularly limited, but is preferably 1-4.

[0175] In this specification, the term "pellet length" refers to the longest length of the long sides of a rectangle circumscribing the projected image of the pellet in all directions. The circumscribing rectangle is set so that the area of the rectangle is minimized.

[0176] In this specification, the "major axis of the cut surface of the pellet" means the length indicated by the straight line connecting the two most distant points on the periphery of the cut surface of the pellet.

[0177] In this specification, the "minor axis of the cross section of the pellet" means the length indicated by a straight line that is perpendicular to the major axis of the cross section of the pellet and connects the two most distant points on the periphery of the cross section of the pellet.

[0178] The major and minor diameters of the cut surface of the pellets can be controlled, for example, by adjusting the diameter of the nozzle of an extruder or the like to change the diameter of the strand.

[0179] Among the above, it is particularly preferable that the pellets of this embodiment have a length of 2 mm or more and 4 mm or less, a major axis of the cross section of the pellets of 2 mm or more and 4 mm or less, and a minor axis of the cross section of the pellets of 2 mm or more and 3 mm or less.

[0180] (Application) The liquid crystal polyester composition of the embodiment is more preferably used as a molding material used in the production of an injection molded article.

[0181] From the viewpoint that the effect of shortening the plasticization time of the fatty acid metal salt according to the embodiment is likely to be significantly manifested, the pellets according to the embodiment are, for example, preferably used as a molding material in an injection molding machine with a maximum clamping force of 400 kN or less, preferably used as a molding material in an injection molding machine with a maximum clamping force of 100 kN or more and 400 kN or less, more preferably used as a molding material in an injection molding machine with a maximum clamping force of 150 kN or more and 380 kN or less, and even more preferably used as a molding material in an injection molding machine with a maximum clamping force of 200 kN or more and 350 kN or less. The liquid crystal polyester composition of the embodiment exhibits a particularly excellent effect in shortening the plasticization time in an injection molding machine having the above-mentioned maximum mold clamping force.

[0182] As an example, the pellets of the embodiment are preferably used as a molding material in an injection molding machine with a screw diameter (screw diameter) of 20 mm or less, preferably used as a molding material in an injection molding machine with a screw diameter of 10 mm or more and 20 mm or less, and more preferably used as a molding material in an injection molding machine with a screw diameter of 14 mm or more and 18 mm or less. The liquid crystal polyester composition of the embodiment exhibits a particularly excellent effect in shortening the plasticization time in an injection molding machine equipped with a screw having the above-mentioned diameter.

[0183] The reason why the liquid crystal polyester composition of the embodiment exhibits particularly excellent effects in a small injection molding machine as exemplified by the above maximum clamping force and screw diameter is not clear. However, it is thought that in a small injection molding machine, pellets are more likely to clog or get stuck when being fed by the screw than in a larger injection molding machine, making it difficult to feed the pellets. Therefore, it is presumed that the effect of the fatty acid metal salt is more sensitively reflected in a small injection molding machine.

[0184] As described above, the liquid crystal polyester composition of the embodiment is very useful and suitable as a molding material for injection molding machines of various sizes.

[0185] <Method for producing liquid crystal polyester composition> A method for producing a liquid crystal polyester composition according to an embodiment includes a mixing step of mixing a liquid crystal polyester with a fatty acid metal salt, wherein the fatty acid metal salt includes a fatty acid metal salt having a fatty acid with 20 or less carbon atoms, and the sieve residue of the fatty acid metal salt measured in accordance with JIS K 0069 on a sieve having a nominal mesh size of 100 μm as specified in JIS Z 8801 is 0 to 80 mass% of the total mass of the fatty acid metal salt.

[0186] The components to be mixed in the mixing step include the liquid crystal polyester and the fatty acid metal salt, as well as other components that are used as needed, such as inorganic fillers. These include those exemplified in the above "Liquid Crystal Polyester Composition." The fatty acid metal salt to be mixed in the mixing step can be, for example, a powder that satisfies the above-mentioned sieve residue requirement.

[0187] The mixing step may include adhering a fatty acid metal salt to the surface of the pellets containing the liquid crystal polyester.

[0188] First, the liquid crystal polyester constituting the pellets and other components used as needed, such as an inorganic filler, are melt-kneaded and granulated using an extruder to obtain pellets.

[0189] Next, the resulting pellets are mixed with a fatty acid metal salt. This operation allows the fatty acid metal salt to adhere to the surface of the pellets. A known mixer can be used for mixing. The mixer is not particularly limited, but examples include a tumbler mixer. Furthermore, the order in which the pellets are mixed with the fatty acid metal salt is not particularly limited.

[0190] According to the method for producing a liquid crystal polyester composition of the embodiment, the liquid crystal polyester composition of the above embodiment can be produced. Note that the liquid crystal polyester composition of the present invention is not limited to that produced by the method for producing a liquid crystal polyester composition of the above embodiment.

[0191] ≪Injection molded body≫ The molded article of this embodiment uses the liquid crystal polyester composition described above as a molding material.

[0192] The molding method of the molded article of this embodiment is preferably a melt molding method. Examples thereof include injection molding, extrusion molding such as a T-die method or an inflation method, compression molding, blow molding, vacuum molding, and press molding, and among these, injection molding is preferred. That is, the molded article of this embodiment is preferably an injection molded article using the liquid crystal polyester composition as a molding material.

[0193] The molded article of this embodiment is suitable for use as a molded article that is required to have heat deformation resistance, such as electronic parts, OA and AV parts, and heat-resistant tableware.

[0194] Examples of products and parts made from the molded article of this embodiment include bobbins such as optical pickup bobbins and transformer bobbins; relay parts such as relay cases, relay bases, relay sprues, and relay armatures; connectors such as RIMM, DDR, CPU sockets, S / O, DIMM, board-to-board connectors, FPC connectors, and card connectors; reflectors such as lamp reflectors and LED reflectors; holders such as lamp holders and heater holders; diaphragms such as speaker diaphragms; separation claws such as separation claws for copiers and printers; camera module parts; switch parts; motor parts; sensor parts; hard disk drive parts; tableware such as ovenware; vehicle parts; battery parts; aircraft parts; and sealing members such as sealing members for semiconductor elements and sealing members for coils.

[0195] <<Method for manufacturing injection-molded body>> The method for producing an injection-molded article according to the embodiment includes a step of injection-molding a liquid crystal polyester composition to obtain an injection-molded article.

[0196] In the method for producing an injection-molded article according to the embodiment, the liquid crystal polyester composition is preferably injection-molded using an injection molding machine having a maximum clamping force of 400 kN or less. Examples of the clamping force of the injection molding machine (400 kN or less) include those exemplified in the above section on "Liquid Crystal Polyester Composition." The liquid crystal polyester composition of the embodiment is particularly effective in shortening the plasticization time when producing an injection-molded article using an injection molding machine having the above-mentioned maximum mold clamping force.

[0197] In the method for producing an injection-molded article according to the embodiment, the liquid crystal polyester composition is preferably injection-molded using an injection molding machine having a screw diameter of 20 mm or less. Examples of the screw diameter of the injection molding machine (20 mm or less) include those exemplified in the above section "Liquid Crystal Polyester Composition." The liquid crystal polyester composition of the embodiment is particularly effective in shortening the plasticization time when producing an injection-molded article using an injection molding machine equipped with a screw having the above-mentioned diameter.

[0198] The method for producing an injection-molded article according to the embodiment can include a step of obtaining an injection-molded article by injection-molding a liquid crystal polyester composition containing a recycled material of liquid crystal polyester. Examples of recycled materials include runners and sprues that are produced together with the product parts in the manufacturing process of the molded body, as well as defective products, etc. The recycled materials may be the above-mentioned runners, etc. that have been crushed, or may be those that have been remelted and processed into pellets.

[0199] The recycled material may be obtained from any composition containing a liquid crystal polyester, but is preferably a recycled material of the liquid crystal polyester composition of the embodiment. The liquid crystal polyester composition containing the recycled material of liquid crystal polyester can be exemplified by a composition containing the liquid crystal polyester composition from which the recycled material is derived and the liquid crystal polyester composition. That is, a molding material (liquid crystal polyester composition) used as a raw material when obtaining the recycled material can be mixed with a molding material (liquid crystal polyester composition) having the same components (preferably the same composition) as the molding material.

[0200] As a recycled material for the liquid crystal polyester composition of the embodiment, for example, an injection molded article (including a runner, a sprue, etc.) of the liquid crystal polyester composition of the embodiment can be used.

[0201] If the recycled material is a pellet with fatty acid metal salts attached to its surface, the fatty acid metal salts present on the surface during the molding process will be kneaded into the interior of the molded body, and therefore the effect of shortening the plasticization time of the fatty acid metal salts may be relatively reduced in the recycled material. However, the liquid crystal polyester composition of the embodiment contains a specific fatty acid metal salt, which has an excellent effect of shortening the plasticization time, and therefore can exert an excellent effect of shortening the plasticization time even when used as a molding material as a recycled material.

[0202] When the liquid crystal polyester composition used in injection molding contains recycled liquid crystal polyester material, the ratio of recycled material to virgin material (new material that has not been subjected to any molding process other than pelletization) may be, for example, a mass ratio of recycled material:virgin material of 1:99 to 80:20, 10:90 to 70:30, or 20:80 to 60:40. [Example]

[0203] The present invention will now be described in more detail with reference to examples, but the present invention is not limited to the following examples. Measurements were carried out as follows. The third embodiment is a reference example.

[0204] <Measurement> (Flow starting temperature of liquid crystal polyester) Using a flow tester (Shimadzu Corporation, CFT-500EX model), approximately 2 g of liquid crystalline polyester was filled into a cylinder equipped with a die having a nozzle with an inner diameter of 1 mm and a length of 10 mm. The liquid crystalline polyester was melted and extruded from the nozzle while being heated at a rate of 4°C / min under a load of 9.8 MPa. The temperature at which the viscosity reached 4800 Pa·s was measured and defined as the flow initiation temperature.

[0205] (Melting point of fatty acid metal salt) The melting points were measured using a differential scanning calorimeter (Shimadzu Corporation, DSC-50). The melting points of the fatty acid metal salts were determined by the position of the highest endothermic peak that appeared when the temperature was increased at a rate of 20°C / min.

[0206] (Mass reduction rate of fatty acid metal salt) First, the fatty acid metal salt was subjected to heat treatment by being held at 160°C in an air atmosphere for 48 hours, and then cooled to room temperature. The mass (g) of the fatty acid metal salt before and after the heat treatment was measured, and the mass loss rate (%) was calculated using the following formula. Mass reduction rate (%) of fatty acid metal salt = (mass (g) of fatty acid metal salt before heat treatment - mass (g) of fatty acid metal salt after heat treatment) ÷ mass (g) of fatty acid metal salt before heat treatment × 100

[0207] (Average particle size of fatty acid metal salts determined by microscopic observation) The fatty acid metal salt was observed using a video microscope (Keyence Corporation, VHZ-ST) at magnifications of 200 to 1000 times. The particle diameters (length indicated by the straight line connecting the two most distant points on the periphery of the particle image) of 200 or more randomly selected primary particles were measured from the observed images, and the arithmetic mean value of the obtained values was calculated.

[0208] (Sieve residue of fatty acid metal salts) The particle size distribution was measured by dry mechanical sieving in accordance with JIS K 0069 at a temperature of 23°C and a humidity of 50% RH using a sieve (frame diameter 200 mm, plain weave) specified in JIS Z 8801 (2019). The sieves used were sieves with a nominal opening of 250 μm (wire diameter 160 μm), 180 μm (wire diameter 125 μm), 106 μm (wire diameter 75 μm) or 75 μm (wire diameter 50 μm). The sieves were placed in an electric vibrating sieving machine (manufactured by Nitto Kagaku Co., Ltd.), and 100 g of the measurement sample was placed on the sieve and sieved for 10 minutes. The sieves were not stacked, and each sieve was sieved individually, and the sieve residue was calculated using the following formula. Sieve residue (mass%) = Mass of sample remaining on the sieve after sieving (g) ÷ Total mass of sample used for sieving (g) × 100

[0209] <Production of Liquid Crystal Polyester> A reactor equipped with a stirrer, a torque meter, a nitrogen gas inlet tube, a thermometer, and a reflux condenser was charged with 994.5 g (7.2 mol) of 4-hydroxybenzoic acid, 446.9 g (2.4 mol) of 4,4'-dihydroxybiphenyl, 299.0 g (1.8 mol) of terephthalic acid, 99.7 g (0.6 mol) of isophthalic acid, and 1347.6 g (13.2 mol) of acetic anhydride, and 0.2 g of 1-methylimidazole was added as a catalyst. The atmosphere inside the reactor was then thoroughly purged with nitrogen gas.

[0210] Thereafter, the mixture was heated from room temperature to 150°C over 30 minutes while stirring under a nitrogen gas flow, and refluxed for 30 minutes while maintaining the same temperature.

[0211] Next, 2.4 g of 1-methylimidazole was added, and while distilling off the by-product acetic acid and unreacted acetic anhydride, the temperature was raised from 150°C to 320°C over 2 hours and 50 minutes, and after maintaining at 320°C for 30 minutes, the contents were removed and cooled to room temperature.

[0212] The resulting solid was crushed to a particle size of 0.1-1 mm using a crusher, and then heated from room temperature to 250°C over 1 hour in a nitrogen atmosphere, then heated from 250°C to 295°C over 5 hours, and held at 295°C for 3 hours to carry out solid-state polymerization. After solid-state polymerization, the mixture was cooled to obtain a powdered liquid crystalline polyester. The flow initiation temperature of the resulting liquid crystalline polyester was 327°C.

[0213] <Fatty acid metal salts> The following commercially available fatty acid metal salts were used. Unless otherwise specified, the commercially available products were used as they were. Calcium laurate: CS-3, manufactured by Nitto Kasei Kogyo Co., Ltd. Lithium laurate: LS-3, manufactured by Nitto Kasei Kogyo Co., Ltd. Lithium stearate: Li-St, manufactured by Nitto Kasei Kogyo Co., Ltd. Calcium stearate: Ca-St, manufactured by Nitto Kasei Kogyo Co., Ltd. Barium stearate: Ba-St, manufactured by Nitto Kasei Kogyo Co., Ltd. Lithium behenate: LS-7, manufactured by Nitto Kasei Kogyo Co., Ltd. Calcium montanate: CS-8, manufactured by Nitto Kasei Kogyo Co., Ltd. Lithium montanate: LS-8, manufactured by Nitto Kasei Kogyo Co., Ltd.

[0214] [Example 1] (Pellet production) First, the liquid crystal polyester (64 parts by mass) produced above and plate-like inorganic filler mica (YM-25S manufactured by Yamaguchi Mica Co., Ltd.) (36 parts by mass) were melt-kneaded using a twin-screw extruder (PCM-30 manufactured by Ikegai Iron Works Co., Ltd.) at a cylinder temperature of 340°C and a screw rotation speed of 150 rpm to obtain a melt-kneaded product. Next, the obtained melt-kneaded product was discharged in the form of strands through a circular discharge port and cooled, and then the strands were pelletized (cut) to obtain pre-pellets of the liquid crystal polyester.

[0215] Next, a fatty acid metal salt (calcium laurate) was externally added to the surface of the pre-pellets obtained above in the proportions shown in Table 1. The fatty acid metal salt was added as a solid powder in an environment of 25°C. After the addition of the fatty acid metal salt, the mixture was mixed for 10 minutes at a rotation speed of 30 rpm using a tumbler mixer (manufactured by PLAENG, "SKD-25") to obtain pellets of Example 1. In Tables 1 to 4, the amount of fatty acid metal salt added refers to the proportion (mass %) of fatty acid metal salt added to the total mass of the pellet after adding the fatty acid metal salt (the total mass of the liquid crystal polyester, inorganic filler, and added fatty acid metal salt).

[0216] (Production of injection molded products and measurement of plasticization time) Using the injection molding machine shown in the following molding condition 1, the pellets of Example 1 were used as the molding material to mold a 0.3 mm thick thin-walled test piece for measuring flow length (see Figure 1, values in mm) under the following molding condition 1. The test piece was then crushed using a Gran Cutter SPC-II400 from Harmo Co., Ltd. to obtain a crushed product. In this example, this crushed product was regarded as the recycled material under molding condition 1. Next, the recycled material (50 parts by mass) obtained above and the pellets (50 parts by mass) of Example 1 were used as molding materials to mold a 0.3 mm thick thin-walled test piece for measuring flow length (see Figure 1) under the following molding condition 1. The plasticization time during 300 continuous molding shots was measured, and the average value (seconds) and standard deviation (seconds) were calculated. The average value was taken as the plasticization time. The standard deviation was taken as the variation.

[0217] (Molding condition 1) Injection molding machine: FANUC Corporation "Roboshot S2000i-30B" Cylinder temperature: Nozzle 340℃; Front 340℃; Center 330℃; Rear 310℃ Mold temperature: 130℃ Injection speed: 200mm / sec Measurement value: 20mm Suckback value: 4mm Screw diameter: 18mm Screw rotation speed: 50 rpm Holding pressure: 20MPa Cooling time: 10 seconds Back pressure: 4 MPa Maximum clamping force: 300kN

[0218] In addition, to obtain reference values, an ASTM No. 4 dumbbell test piece was molded under the following molding conditions 2 using an injection molding machine shown in the following molding conditions 2, using the pellets of Example 1 as the molding material. The test piece was then crushed using a Gran Cutter SPC-II400 from Harmo Co., Ltd. to obtain a crushed product. In this example, this crushed product was regarded as the recycled material under molding condition 2. Next, the recycled material obtained above (50 parts by mass) and the pellets of Example 1 (50 parts by mass) were used as molding materials to mold ASTM No. 4 dumbbell test pieces under the following molding conditions 2. The plasticization time during 300 continuous molding shots was measured, and the average value (seconds) was calculated and used as the plasticization time.

[0219] (Molding condition 2) Injection molding machine: Nissei Plastic Industrial Co., Ltd. "PNX40-5A" Cylinder temperature: Nozzle 340℃; Front 340℃; Center 330℃; Rear 310℃ Mold temperature: 130℃ Injection speed: 150mm / sec Measurement value: 26mm Suckback value: 2mm Screw diameter: 22mm Screw rotation speed: 200 rpm Holding pressure: 28MPa Cooling time: 15 seconds Back pressure: 2.2 MPa Maximum clamping force: 405kN

[0220] [Examples 2 to 3, Comparative Examples 1 to 8] Pellets and injection-molded articles were produced in the same manner as in Example 1, except that the fatty acid metal salt was changed as shown in Table 1.

[0221] The fatty acid metal salts used in Example 3 and Comparative Examples 4, 5, 7, and 8 were prepared by classifying commercially available fatty acid metal salts using an electric vibrating sieve (manufactured by Nitto Kagaku Co., Ltd.) and mixing them appropriately to obtain the sieve residues shown in Table 1. The sieves used were those with a nominal mesh size of 250 μm (wire diameter 160 μm), a nominal mesh size of 180 μm (wire diameter 125 μm), a nominal mesh size of 106 μm (wire diameter 75 μm), and a nominal mesh size of 75 μm (wire diameter 50 μm).

[0222] [Examples 1-2 to 1-4] Pellets and injection-molded bodies were produced in the same manner as in Example 1, except that instead of the fatty acid metal salt used in Example 1, a commercially available fatty acid metal salt (calcium laurate) was used, which was classified using an electric vibration sieve (manufactured by Nitto Kagaku Co., Ltd.) and appropriately mixed to obtain the sieve residue shown in Table 2. The sieves used were those with a nominal mesh size of 250 μm (wire diameter 160 μm), a nominal mesh size of 180 μm (wire diameter 125 μm), a nominal mesh size of 106 μm (wire diameter 75 μm), and a nominal mesh size of 75 μm (wire diameter 50 μm).

[0223] [Example 2-2] Pellets and injection-molded articles were produced in the same manner as in Example 2 above, except that the amount of fatty acid metal salt (lithium laurate) added was changed as shown in Table 3.

[0224] [Example 2-3] Pellets and injection-molded articles were produced in the same manner as in Example 2 above, except that the pellet production was changed as follows (see Table 4). (Pellet production) The liquid crystal polyester (55 parts by mass), plate-shaped inorganic filler mica (Yamaguchi Mica Co., Ltd. "YM-25S") (8 parts by mass), plate-shaped inorganic filler talc (Nippon Talc Co., Ltd. "Rose K") (25 parts by mass), and fibrous inorganic filler milled glass fiber (Central Glass Fiber Co., Ltd. "EFH75-01") (12 parts by mass) were melt-kneaded using a twin-screw extruder (Ikegai Iron Works Co., Ltd. "PCM-30") at a cylinder temperature of 340 ° C. and a screw rotation speed of 150 rpm to obtain a melt-kneaded product. The resulting melt-kneaded product was then extruded into strands through a circular nozzle, cooled, and pelletized (cut) to obtain pre-pellets of the liquid crystal polyester. Next, a fatty acid metal salt (lithium laurate) was externally added to the surface of the pre-pellets obtained above in the proportion shown in Table 4. The fatty acid metal salt was added as a solid powder in an environment of 25°C. After the addition of the fatty acid metal salt, the mixture was mixed for 10 minutes at a rotation speed of 30 rpm using a tumbler mixer (manufactured by PLAENG, "SKD-25") to obtain pellets of Example 2-3.

[0225] The results of the above measurements are shown in Tables 1 to 4. The plasticization time was evaluated using the value when an injection molding machine with a screw diameter of 18 mm was used. A plasticization time of 6 seconds or less was judged to be good.

[0226] [Table 1]

[0227] [Table 2]

[0228] [Table 3]

[0229] [Table 4]

[0230] As shown in Table 1, in Comparative Examples 4 to 8, in which fatty acid metal salts having more than 20 carbon atoms were used, the plasticization time tended to be longer even when the sieve residue on the 106 μm mesh sieve was 80 mass% or less.

[0231] In addition, in Comparative Examples 1 to 3, in which a fatty acid metal salt with a sieve retention of more than 80% by mass on a 106 μm mesh sieve was used, the plasticization time tended to be long even though the fatty acid metal salt had a fatty acid carbon number of 20 or less.

[0232] In contrast, as shown in Table 1, in Examples 1 to 3, which used fatty acid metal salts having a fatty acid carbon number of 20 or less and a sieve residue of 80 mass% or less on a sieve with a mesh size of 106 μm, the plasticization time was short and the variation was small, and the reduction in plasticization time and stability were excellent.

[0233] No correlation was found between the melting point, mass loss rate, and average particle size determined by microscopic observation of the fatty acid metal salts shown in Table 1 and the plasticization time. This also confirms that the above-mentioned specifications for the number of fatty acid carbon atoms and sieve residue are important factors in shortening the plasticization time and achieving stability.

[0234] Similarly, as shown in Table 2, in Examples 1-2 to 1-4 in which the sieve residue of the fatty acid metal salt on a sieve with a nominal mesh size of 106 μm was changed within the range of 0 to 80 mass%, the plasticization time was short and the variation was small, and the reduction in plasticization time and stability were excellent.

[0235] Similarly, as shown in Table 3, in Example 2-2 in which the amount of fatty acid metal salt added was changed, the plasticization time was short and the variation was small, and the reduction in plasticization time and stability were excellent.

[0236] As shown in Table 4, even in Example 2-3 in which the type and blending ratio of the filler were changed, the plasticization time was short and the variation in the plasticization time was small, and the reduction in the plasticization time and stability were excellent.

[0237] The above results were more pronounced when an injection molding machine with a screw diameter of 18 mm was used than when an injection molding machine with a screw diameter of 22 mm was used (see Table 1).

[0238] Furthermore, it was shown that the pellets of the above examples can exhibit good properties in terms of shortening the plasticization time and stability, even when mixed with recycled materials.

[0239] The configurations and combinations thereof in each embodiment are merely examples, and additions, omissions, substitutions, and other modifications of the configurations are possible without departing from the spirit of the present invention. Furthermore, the present invention is not limited to each embodiment, but is limited only by the scope of the claims.

Claims

1. A liquid crystal polyester pellet and a fatty acid metal salt are included, The fatty acid metal salt includes a fatty acid metal salt having a fatty acid having 20 or less carbon atoms, the fatty acid metal salt is a metal salt of lauric acid or stearic acid, At least a portion of the fatty acid metal salt adheres to the surface of the pellet; the content of the fatty acid metal salt is 0.003 to 5% by mass relative to the total mass of the liquid crystal polyester composition, the fatty acid metal salt has a sieve residue on a sieve having a nominal mesh size of 106 μm as defined in JIS Z 8801, measured in accordance with JIS K 0069, of 0 to 80% by mass relative to the total mass of the fatty acid metal salt; The liquid crystal polyester composition, wherein the fatty acid metal salt has a sieve residue on a sieve having a nominal mesh size of 75 μm as defined in JIS Z 8801, as measured in accordance with JIS K 0069, of 40 to 100% by mass based on the total mass of the fatty acid metal salt.

2. The liquid crystal polyester composition according to claim 1 , wherein the fatty acid metal salt comprises a fatty acid metal salt having a fatty acid having 16 or less carbon atoms.

3. 3. The liquid crystal polyester composition according to claim 1, wherein the fatty acid metal salt has a residue on a sieve having a nominal mesh size of 250 μm as defined in JIS Z 8801, as measured in accordance with JIS K 0069, of 0 to 30% by mass with respect to the total mass of the fatty acid metal salt.

4. 4. The liquid crystal polyester composition according to claim 1, wherein the fatty acid metal salt has a sieve residue measured in accordance with JIS K 0069 and having a nominal mesh size of 180 μm as defined in JIS Z 8801, and the sieve residue is 0 to 50 mass% based on the total mass of the fatty acid metal salt.

5. The liquid crystal polyester composition according to any one of claims 1 to 4, wherein the fatty acid metal salt has a melting point of 130 to 300°C.

6. 6. The liquid crystal polyester composition according to claim 1, wherein the metal in the fatty acid metal salt is calcium or lithium.

7. The liquid crystal polyester composition according to claim 6 , wherein the fatty acid metal salt is calcium laurate or lithium laurate.

8. The liquid crystal polyester composition according to any one of claims 1 to 7, which is used as a molding material in an injection molding machine having a maximum clamping force of 400 kN or less.

9. The liquid crystal polyester composition according to any one of claims 1 to 8, which is used as a molding material in an injection molding machine having a screw diameter of 20 mm or less.

10. A mixing step of mixing a liquid crystal polyester and a fatty acid metal salt. A method for producing the liquid crystal polyester composition according to any one of claims 1 to 9.

11. The method for producing a liquid crystal polyester composition according to claim 10 , wherein the mixing step includes adhering a fatty acid metal salt to the surface of pellets containing the liquid crystal polyester.

12. A method for producing an injection-molded article, comprising a step of injection-molding the liquid crystal polyester composition according to any one of claims 1 to 9 to obtain an injection-molded article.

13. The method for producing an injection-molded article according to claim 12, wherein the liquid crystal polyester composition is injection-molded using an injection molding machine having a maximum clamping force of 400 kN or less.

14. The method for producing an injection-molded article according to claim 12 or 13, wherein the liquid crystal polyester composition is injection-molded using an injection molding machine having a screw diameter of 20 mm or less.

15. The method for producing an injection-molded article according to any one of claims 12 to 14, wherein the liquid crystal polyester composition contains a recycled material of liquid crystal polyester.

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