Liquid crystal polyester powder, composition, method for producing the composition, method for producing a film, and method for producing a laminate

Abstract

The present invention relates to a liquid crystal polyester powder containing a liquid crystal polyester. In the volume-based cumulative particle diameter distribution curve obtained by laser diffraction / scattering-type particle diameter distribution measurement, when D90 is defined as the particle diameter at which the cumulative volume ratio from the small particle side becomes 90%, the D90 of the liquid crystal polyester powder is 20 μm or less.

Description

[Technical Field]

[0001] The present invention relates to liquid crystal polyester powder, compositions, methods for producing compositions, methods for producing films, and methods for producing laminates. This application claims priority based on Japanese Patent Application No. 2021-015002, filed in Japan on February 2, 2021, and the contents of that application are incorporated herein by reference. [Background technology]

[0002] Insulating materials are used in printed circuit boards on which electronic components are mounted. In recent years, with the development of communication systems and other factors, there has been a demand for further improvements in the physical properties of insulating materials, such as dielectric properties. For example, Patent Document 1 describes an insulating resin composition comprising an epoxy resin containing silyl groups, a curing agent, and an inorganic filler such as silica, for the purpose of reducing dielectric loss. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2017-66360 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] However, the mechanical strength of the film obtained from the resin composition described in Patent Document 1 had not been sufficiently investigated. Furthermore, considering its application to next-generation mobile communication systems, conventional substrate materials are highly likely to have insufficient dielectric properties at high frequencies.

[0005] Liquid crystal polyester film is attracting attention as an electronics substrate material due to its excellent high-frequency properties and low water absorption.

[0006] The object of the present invention is to provide a liquid crystal polyester powder capable of improving the mechanical strength of a liquid crystal polyester film produced using the liquid crystal polyester powder. Another object of the present invention is to provide a liquid crystal polyester composition containing a medium and the liquid crystal polyester powder, and a method for producing the liquid crystal polyester composition. Another object of the present invention is to provide a method for producing a liquid crystal polyester film and a method for producing a laminate using the liquid crystal polyester composition.

Means for Solving the Problems

[0007] As a result of intensive studies to solve the above problems, the present inventors have found that a liquid crystal polyester film excellent in mechanical strength can be obtained by using a liquid crystal polyester powder having a specific range of D 90 and have completed the present invention. That is, the present invention has the following aspects.

[0008] <1>A liquid crystal polyester powder containing a liquid crystal polyester, In the volume-based cumulative particle size distribution curve measured by laser diffraction / scattering particle size distribution measurement, the particle size at which the cumulative volume ratio from the small particle side is 90% is D 90 When it is set as the above D 90 is 20 μm or less, the liquid crystal polyester powder. <2>The liquid crystal polyester powder according to <1>, wherein the ratio of particles having a particle size of 30 μm or more measured by laser diffraction / scattering particle size distribution measurement is 3% by volume or less with respect to the total volume of the liquid crystal polyester powder. <3>The liquid crystal polyester powder according to <1> or <2>, wherein the ratio of particles having a particle size of 20 μm or more measured by laser diffraction / scattering particle size distribution measurement is 7% by volume or less with respect to the total volume of the liquid crystal polyester powder. <4>The liquid crystal polyester powder according to any one of <1> to <3>, wherein the liquid crystal polyester has a structural unit containing a naphthalene structure. <5>The content of the structural unit containing the naphthalene structure in the liquid crystal polyester is 40 mol% or more with respect to 100 mol% of the total amount of all structural units in the liquid crystal polyester, the liquid crystal polyester powder according to <4>. <6>The liquid crystal polyester has a structural unit represented by the following formula (1), a structural unit represented by the following formula (2), and a structural unit represented by the following formula (3), the liquid crystal polyester powder according to any one of <1> to <5>. (1)-O-Ar1-CO- (2)-CO-Ar2-CO- (3)-X-Ar3-Y- [In 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 group represented by Ar1, Ar2 or Ar3 may each independently be substituted with a halogen atom, an alkyl group having 1 to 10 carbon atoms or an aryl group having 6 to 20 carbon atoms.] (4)-Ar4-Z-Ar5- [In formula (4), Ar4 and Ar5 each independently represent a phenylene group or a naphthylene group. 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 each independently be substituted with a halogen atom, an alkyl group having 1 to 10 carbon atoms or an aryl group having 6 to 20 carbon atoms.] <7>A liquid crystal polyester composition containing a medium and the liquid crystal polyester powder according to any one of <1> to <6>. <8>The liquid crystal polyester powder is insoluble in the medium, the liquid crystal polyester composition according to <7>. <9>Furthermore, containing a resin soluble in the medium, the liquid crystal polyester composition according to <7> or <8>. <10> The resin soluble in the medium is a liquid crystal polyester soluble in the medium. <9> The liquid crystal polyester composition described above. <11> The medium and the aforementioned <1> ~ <6> The liquid crystal polyester powder described in any one of the above, which includes mixing with the above <7> ~ <10> A method for producing a liquid crystal polyester composition as described in any one of the following. <12> On the support, <7> ~ <10> A method for producing a liquid crystal polyester film, comprising applying a liquid crystal polyester composition described in any one of the above, and heat-treating it to obtain a liquid crystal polyester film containing liquid crystal polyester. <13> On the support, <7> ~ <10> A method for producing a laminate, comprising applying a liquid crystal polyester composition described in any one of the above, heat-treating it to form a liquid crystal polyester film containing liquid crystal polyester, thereby obtaining a laminate comprising the support and the liquid crystal polyester film. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a liquid crystal polyester powder that can improve the mechanical strength of the liquid crystal polyester film produced. Furthermore, according to the present invention, a liquid crystal polyester composition containing a medium and the liquid crystal polyester powder, and a method for producing the liquid crystal polyester composition can be provided. Furthermore, according to the present invention, it is possible to provide a method for manufacturing a liquid crystal polyester film and a method for manufacturing a laminate using the liquid crystal polyester composition. [Brief explanation of the drawing]

[0010] [Figure 1A] This is a schematic diagram showing the manufacturing process of a liquid crystal polyester film and laminate according to one embodiment of the present invention. [Figure 1B] This is a schematic diagram showing the manufacturing process of a liquid crystal polyester film and laminate according to one embodiment of the present invention. [Figure 1C] This is a schematic diagram showing the manufacturing process of a liquid crystal polyester film and laminate according to one embodiment of the present invention. [Figure 1D]This is a schematic diagram showing the manufacturing process of a liquid crystal polyester film and laminate according to one embodiment of the present invention. [Figure 2] This is a schematic diagram showing the structure of a liquid crystal polyester film according to one embodiment of the present invention. [Figure 3] This is a schematic diagram showing the structure of a laminate according to one embodiment of the present invention. [Modes for carrying out the invention]

[0011] The following describes embodiments of the liquid crystal polyester powder, composition, method for producing the composition, method for producing the film, and method for producing the laminate of the present invention.

[0012] ≪Liquid crystal polyester powder≫ The liquid crystal polyester powder of the embodiment is a liquid crystal polyester powder containing liquid crystal polyester, wherein the particle size at which the cumulative volume ratio from the smallest particle side is 90% in the volume-based cumulative particle size distribution curve obtained by laser diffraction / scattering particle size distribution measurement is D 90 When this is the case, the above D 90 The particle size is 20 μm or less.

[0013] According to the embodiment of the liquid crystal polyester powder, a liquid crystal polyester composition containing a medium and liquid crystal polyester powder can be provided. The liquid crystal polyester composition makes it possible to improve the mechanical strength of the liquid crystal polyester film produced. The liquid crystal polyester composition is suitable as a raw material for the liquid crystal polyester film or laminate according to the embodiment. Details of the liquid crystal polyester film will be described later.

[0014] In this specification, the "mechanical strength" of a liquid crystal polyester film is evaluated by the "tensile strength" and "tensile strength strain" obtained by the measurement method described later.

[0015] The liquid crystal polyester powder is the D 90 The particle size is 20 μm or less, preferably 15 μm or less, and more preferably 10 μm or less. D of the liquid crystal polyester powder90 being below the above upper limit value enables the improvement of the mechanical strength of a liquid crystal polyester film produced from a composition containing the liquid crystal polyester powder compared to the case where 90 the regulation that D is 20 μm or less is not satisfied. Also, the lower limit value of D of the liquid crystal polyester powder is not particularly limited, but from the viewpoint of ease of handling of the powder, it is preferably 5 μm or more, more preferably 6 μm or more, and even more preferably 7 μm or more. 90 The upper limit value and the lower limit value of D of the above liquid crystal polyester powder can be freely combined. As an example of the numerical range of the value of D of the above liquid crystal polyester powder, it is preferably 5 μm or more and 20 μm or less, more preferably 6 μm or more and 15 μm or less, and even more preferably 7 μm or more and 10 μm or less. 90 90

[0016] In the cumulative particle size distribution curve based on volume by laser diffraction / scattering particle size distribution measurement, when the particle size at which the cumulative volume ratio from the small particle side becomes 50% is defined as D 50 the value of D of the liquid crystal polyester powder of the embodiment is not particularly limited as long as it satisfies the value of D 50 described above. As an example of the value of D of the liquid crystal polyester powder, it may be 0.1 or more and 15 μm or less, may be 0.5 μm or more and 10 μm or less, or may be 0.5 μm or more and 7 μm or less. 90 50

[0017] The value of the above D 90 - the value of the above D 50 (D 90 - D 50 ) may be, for example, 10 μm or less or 5 μm or less.

[0018] D and D of the liquid crystal polyester powder 50 can be measured by the following method. 90 A dispersion of liquid crystal polyester powder, prepared by dispersing liquid crystal polyester powder in pure water, is measured using a laser diffraction / scattering particle size distribution analyzer (e.g., HORIBA's "LA-950V2"), with the refractive index of pure water set to 1.333. The volume-based cumulative particle size distribution of the liquid crystal polyester powder is then measured. The particle size (μm) at which the cumulative volume proportion from the smallest particles reaches 50% is defined as D. 50 D is defined as the particle diameter (μm) at which the cumulative volume percentage from the small particle side becomes 90%. 90 Let's assume that.

[0019] Furthermore, in the embodiment, the liquid crystal polyester powder preferably has a particle size of 30 μm or more, as measured by the laser diffraction / scattering particle size distribution measurement described above, as 3% by volume or less, and more preferably 0% by volume, relative to the total volume of the liquid crystal polyester powder.

[0020] Using a liquid crystal polyester powder in which the proportion of particles with a particle size of 30 μm or more is below the above upper limit makes it possible to improve the mechanical strength of the liquid crystal polyester film produced.

[0021] Furthermore, in the embodiment, the liquid crystal polyester powder preferably has a particle size of 20 μm or more, as measured by the laser diffraction / scattering particle size distribution measurement described above, as 7 volume% or less, more preferably 5 volume% or less, even more preferably 2 volume% or less, and particularly preferably 0 volume%.

[0022] Using a liquid crystal polyester powder in which the proportion of particles with a particle size of 20 μm or more is below the above upper limit, it is possible to manufacture a liquid crystal polyester film with even better mechanical strength.

[0023] The percentage (by volume) of particles with a particle diameter of 20 μm or 30 μm or larger in liquid crystal polyester powder can be determined from the volume-based cumulative particle diameter distribution obtained by the laser diffraction / scattering particle diameter distribution measurement described above.

[0024] Liquid crystal polyester powder, D 90 The reason why a small value of [the specified value], and furthermore, a low proportion of particles with a particle size of 20 μm or more or 30 μm or more, improves the mechanical strength of the manufacturable liquid crystal polyester film is not clear, but the following reasons can be inferred. As will be explained later, a liquid crystal polyester film can be manufactured by coating a liquid crystal polyester composition containing liquid crystal polyester powder onto a support and then heat-treating it. The liquid crystal polyester composition may also contain other resins, such as those not corresponding to liquid crystal polyester powder. In the resulting liquid crystal polyester film, portions derived from individual liquid crystal polyester powders remain, not completely homogenized with each other or with other resin portions. It is thought that the bonding at the surface interface of these liquid crystal polyester powders tends to weaken under tensile stress on the film, and this tendency is thought to be more pronounced with larger particle sizes. It is presumed that the tensile strength of the film is increased in this embodiment by reducing the proportion of liquid crystal polyester powder with large particle sizes.

[0025] The liquid crystal polyester powder of the embodiment may contain liquid crystal polyester, or it may consist solely of liquid crystal polyester. The liquid crystal polyester content relative to 100% by mass of liquid crystal polyester powder in the embodiment may be 50 to 100% by mass, or 80 to 95% by mass.

[0026] The details of the liquid crystal polyester contained in the liquid crystal polyester powder of this embodiment will be described below.

[0027] (Liquid crystal polyester) The liquid crystal polyester according to this embodiment is a polyester that exhibits liquid crystal properties in a molten state, and is preferably melted at a temperature of 450°C or lower. 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 fully aromatic liquid crystal polyester having only structural units derived from aromatic compounds as raw material monomers.

[0028] In this specification, "derived from" means that the chemical structure of the raw material monomer changes due to polymerization, but no other structural changes occur.

[0029] Typical examples of liquid crystal polyesters include polymers obtained by polycondensation (condensation) of aromatic hydroxycarboxylic acid, aromatic dicarboxylic acid, and at least one compound selected from the group consisting of aromatic diol, aromatic hydroxyamine, and aromatic diamine; polymers obtained by polymerizing multiple types of aromatic hydroxycarboxylic acid; polymers obtained by polymerizing aromatic dicarboxylic acid and at least one compound selected from the group consisting of aromatic diol, aromatic hydroxyamine, and aromatic diamine; and polymers obtained by polymerizing polyester such as polyethylene terephthalate with aromatic hydroxycarboxylic acid.

[0030] In particular, among the liquid crystal polyesters, polymers obtained by polycondensation (condensation) of aromatic hydroxycarboxylic acid, aromatic dicarboxylic acid, and at least one compound selected from the group consisting of aromatic diol, aromatic hydroxyamine, and aromatic diamine are preferred.

[0031] Here, aromatic hydroxycarboxylic acids, aromatic dicarboxylic acids, aromatic diols, aromatic hydroxyamines, and aromatic diamines may be independently replaced by polymerizable ester-forming derivatives thereof, in whole or in part.

[0032] Examples of polymerizable derivatives of compounds having a carboxyl group, such as aromatic hydroxycarboxylic acids and aromatic dicarboxylic acids, include esters, acid halides, and acid anhydrides. Examples of esters include compounds obtained by converting the carboxyl group to an alkoxycarbonyl group or an aryloxycarbonyl group. Examples of acid halides include compounds obtained by converting the carboxyl group to a haloformyl group. Examples of acid anhydrides include compounds obtained by converting the carboxyl group to an acyloxycarbonyl group.

[0033] Examples of polymerizable derivatives of compounds having a hydroxyl group, such as aromatic hydroxycarboxylic acids, aromatic diols, and aromatic hydroxyamines, include those obtained by acyling the hydroxyl group to convert it into an acyloxy group (acylated compounds). Examples of polymerizable derivatives of compounds having an amino group, such as aromatic hydroxyamines and aromatic diamines, include compounds (acylated compounds) obtained by acyling the amino group to convert it into an acylamino group.

[0034] Among the examples of polymerizable derivatives exemplified, acylated products obtained by acyling aromatic hydroxycarboxylic acids and aromatic diols are preferred as raw material monomers for liquid crystal polyesters.

[0035] 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 independently substituted with halogen atoms, C1-C10 alkyl groups, or C6-C20 aryl groups.

[0036] The liquid crystal polyester according to the embodiment more preferably has a 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)").

[0037] (1)-O-Ar1-CO- (2) New CO-Ar2-CO- (3)-X-Ar3-Y-

[0038] [In formulas (1) to (3), Ar1 represents a phenylene group, a naphthylene group, or a biphenylylene group. Ar2 and Ar3 independently represent a phenylene group, a naphthylene group, a biphenylylene group, or a group represented by the following formula (4). X and Y independently represent an oxygen atom or an imino group (-NH-). One or more hydrogen atoms in the group represented by Ar1, Ar2, or Ar3 may be independently substituted with a halogen atom, a C1-C10 alkyl group, or a C6-C20 aryl group.

[0039] (4)-Ar4-Z-Ar5-

[0040] [In formula (4), Ar4 and Ar5 independently represent a phenylene group or a naphthylene group. 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 independently substituted with a halogen atom, a C1-C10 alkyl group, or a C6-C20 aryl group.

[0041] In structural unit (3), X and Y are preferably oxygen atoms.

[0042] Examples of halogen atoms that can be substituted for hydrogen atoms include fluorine atoms, chlorine atoms, bromine atoms, and iodine atoms.

[0043] Examples of C1-C10 alkyl groups that can be substituted for hydrogen atoms include methyl, ethyl, 1-propyl, isopropyl, 1-butyl, isobutyl, sec-butyl, tert-butyl, 1-hexyl, 2-ethylhexyl, 1-octyl, and 1-decyl groups.

[0044] Examples of aryl groups having 6 to 20 carbon atoms that can be substituted with a hydrogen atom include monocyclic aromatic groups such as phenyl, orthotolyl, metatolyl, and paratolyl groups, as well as fused aromatic groups such as 1-naphthyl and 2-naphthyl groups.

[0045] When one or more hydrogen atoms in the group represented by Ar1, Ar2, Ar3, Ar4, or Ar5 are substituted with the halogen atom, the C1-C10 alkyl group, or the C6-C20 aryl group, the number of groups substituting the hydrogen atoms is preferably one or two, and more preferably one, for each group represented by Ar1, Ar2, Ar3, Ar4, or Ar5, independently of each other.

[0046] Examples of alkylidene groups having 1 to 10 carbon atoms include methylene group, ethylidene group, isopropylidene group, 1-butylidene group, and 2-ethylhexylidene group.

[0047] The liquid crystal polyester according to the embodiment preferably contains structural units including a naphthalene structure. Liquid crystal polyester containing structural units including a naphthalene structure tends to have excellent dielectric properties.

[0048] As a liquid crystal polyester having structural units containing a divalent naphthalene structure, in a liquid crystal polyester having the above structural unit (1), the above structural unit (2), and the above structural unit (3), it is preferable that at least one of the multiple Ar1, Ar2, Ar3, Ar4, and Ar5 is a naphthylene group.

[0049] The above liquid crystal polyester includes the following liquid crystal polyester. A liquid crystal polyester having structural units represented by the following formula (1), structural units represented by the following formula (2), and structural units represented by the following formula (3). (1)-O-Ar1-CO- (2) New CO-Ar2-CO- (3)-O-Ar3-O- (Ar1 represents a 2,6-naphthylene group, a 1,4-phenylene group, or a 4,4'-biphenylylene group.) Ar2 and Ar3 independently represent a 2,6-naphthylene group, a 2,7-naphthylene group, a 1,4-phenylene group, a 1,3-phenylene group, or a 4,4'-biphenylylene group. The hydrogen atoms in the groups represented by Ar1, Ar2, or Ar3 may each be independently substituted with halogen atoms, C1-C10 alkyl groups, or C6-C20 aryl groups.

[0050] Examples of liquid crystal polyesters having structural units represented by the above formulas (1) to (3) include those having structural units represented by the following formula (1), structural units represented by the following formula (2), and structural units represented by the following formula (3). (1)-O-Ar1-CO- (2) New CO-Ar2-CO- (3)-O-Ar3-O- (Ar1 represents a naphthylene group, Ar2 represents a naphthylene group or a phenylene group, and Ar3 represents a phenylene group.) The hydrogen atoms in the groups represented by Ar1, Ar2, or Ar3 may each be independently substituted with halogen atoms, C1-C10 alkyl groups, or C6-C20 aryl groups.

[0051] In liquid crystal polyester, the content of structural units containing naphthalene structures 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 (calculated by dividing the mass of each structural unit constituting the liquid crystal polyester by the formula weight of that structural unit to obtain the equivalent amount of substance (moles) of each structural unit, and then summing them up). By having a content of structural units containing naphthalene structures above the above lower limit, it is possible to further reduce the dielectric constant of the liquid crystal polyester. In liquid crystal polyester, the content of structural units containing naphthalene structures is preferably 90 mol% or less, more preferably 85 mol% or less, and even more preferably 80 mol% or less, relative to the total amount of all structural units in the liquid crystal polyester (100 mol%). By having a content of structural units containing naphthalene structures below the above upper limit, reaction stability during the production of liquid crystal polyester can be ensured. Examples of numerical ranges for the content of structural units containing the naphthalene structure described above include 40 mol% to 90 mol%, 50 mol% to 85 mol%, 55 mol% to 85 mol%, and 60 mol% to 80 mol%.

[0052] In the embodiment, the liquid crystal polyester preferably has Ar1 as a 2,6-naphthylene group. A liquid crystal polyester in which Ar1 is a 2,6-naphthylene group preferably has the above structural unit (1), the above structural unit (2), and the above structural unit (3). The liquid crystal polyester according to this embodiment may contain 40 mol% or more of structural units in which Ar1 is a 2,6-naphthylene group, relative to the total amount of all structural units in the liquid crystal polyester, or it may contain 40 mol% to 90 mol%, 50 mol% to 85 mol%, or 55 mol% to 85 mol%.

[0053] Structural unit (1) is a structural unit derived from an aromatic hydroxycarboxylic acid. Examples of the aromatic hydroxycarboxylic acids include 4-hydroxybenzoic acid, meta-hydroxybenzoic 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 in the aromatic ring of these aromatic hydroxycarboxylic acids are 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 liquid crystal polyesters. The structural unit (1) is preferably one in which Ar1 is a 1,4-phenylene group (for example, a structural unit derived from 4-hydroxybenzoic acid) and one in which Ar1 is a 2,6-naphthylene group (for example, a structural unit derived from 6-hydroxy-2-naphthoic acid).

[0054] Structural unit (2) is a structural unit derived from an aromatic dicarboxylic acid. Examples of the aforementioned aromatic dicarboxylic acids include terephthalic acid, isophthalic acid, biphenyl-4,4'-dicarboxylic acid, 2,6-naphthalenedicarboxylic acid, diphenyl ether-4,4'-dicarboxylic acid, diphenylthioether-4,4'-dicarboxylic acid, and aromatic dicarboxylic acids in which some of the hydrogen atoms in the aromatic ring of these aromatic dicarboxylic acids are substituted with substituents selected from the group consisting of alkyl groups, aryl groups, and halogen atoms. The aforementioned aromatic dicarboxylic acids may be used alone or in combination of two or more in the production of liquid crystal polyesters. The structural unit (2) is preferably one in which Ar2 is a 1,4-phenylene group (for example, a structural unit derived from terephthalic acid), one in which Ar2 is a 1,3-phenylene group (for example, a structural unit derived from isophthalic acid), one in which Ar2 is a 2,6-naphthylene group (for example, a structural unit derived from 2,6-naphthalenedicarboxylic acid), and one in which Ar2 is a diphenyl ether-4,4'-diyl group (for example, a structural unit derived from diphenyl ether-4,4'-dicarboxylic acid).

[0055] Structural unit (3) is a structural unit derived from an aromatic diol, aromatic hydroxyamine, or 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 aforementioned aromatic diol, aromatic hydroxyamine, or aromatic diamine may be used alone or in combination of two or more in the production of liquid crystal polyester. As structural unit (3), those in which Ar3 is a 1,4-phenylene group (for example, structural units derived from hydroquinone, 4-aminophenol, or 1,4-phenylenediamine) and those in which Ar3 is a 4,4'-biphenylylene group (for example, structural units derived from 4,4'-dihydroxybiphenyl, 4-amino-4'-hydroxybiphenyl, or 4,4'-diaminobiphenyl) are preferred.

[0056] Furthermore, if the liquid crystal polyester film obtained from the liquid crystal polyester composition of the embodiment requires particularly good heat resistance, it is preferable to have fewer substituents, and it is especially preferable that it does not have substituents such as alkyl groups.

[0057] Next, examples of liquid crystal polyesters particularly suitable for application to the liquid crystal polyester composition of the embodiment are given below. Specific examples of preferred liquid crystal polyesters include copolymers composed of structural units derived from monomers in the following combinations.

[0058] 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 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.

[0059] The content of the structural units (1) of 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 especially preferably 55 to 70 mol%, relative to the total amount of all structural units constituting the liquid crystal polyester (the amount of substance equivalent (moles) of each structural unit obtained by dividing the mass of each structural unit constituting the liquid crystal polyester by the formula weight of each structural unit, and then summing them up). When the content of structural unit (1) of the liquid crystal polyester is 30 mol% or more, the heat resistance and hardness of the film obtained using the liquid crystal polyester composition of this embodiment tend to improve. Furthermore, when the content of structural unit (1) is 80 mol% or less, the melt viscosity can be lowered. As a result, the temperature required for molding the liquid crystal polyester tends to be lower.

[0060] The content of the liquid crystal polyester structural units (2) 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%, relative to the total amount of all structural units constituting the liquid crystal polyester.

[0061] The content of the liquid crystal polyester structural units (3) 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%, relative to the total amount of all structural units constituting the liquid crystal polyester.

[0062] In liquid crystal polyester, the ratio of the content of structural unit (2) to the content of structural unit (3) is expressed as [content of structural unit (2)] / [content of structural unit (3)] (moles / moles), and is preferably 0.9 to 1.1, more preferably 0.95 to 1.05, and even more preferably 0.98 to 1.02.

[0063] In liquid crystal polyester, the ratio of the content of structural unit (3) to the content of structural unit (1) is expressed as [content of structural unit (3)] / [content of structural unit (1)] (moles / moles), and is preferably 0.2 to 1.0, more preferably 0.25 to 0.85, and even more preferably 0.3 to 0.75.

[0064] The liquid crystal polyester may have only one type of structural unit (1) to (3), or two or more types, independently. Furthermore, the liquid crystal polyester may have one or more structural units other than structural units (1) to (3), but their content is preferably 10 mol% or less, more preferably 5 mol% or less, relative to the total amount of all structural units of the liquid crystal polyester.

[0065] The sum of the content of structural unit (1) of the liquid crystal polyester resin, the content of structural unit (2) of the liquid crystal polyester, and the content of structural unit (3) of the liquid crystal polyester shall not exceed 100 mol%.

[0066] In this embodiment, it is also possible to use a liquid crystal polyester mixture in which multiple types of liquid crystal polyesters are mixed. Here, a liquid crystal polyester resin mixture is a mixture of liquid crystal polyester resins having different flow initiation temperatures. In the liquid crystal polyester resin mixture, the one with the highest flow initiation temperature is designated as the first liquid crystal polyester resin, and the one with the lowest flow initiation temperature is designated as the second liquid crystal polyester resin. A liquid crystal polyester resin mixture consisting substantially of the first liquid crystal polyester and the second liquid crystal polyester is preferred.

[0067] Furthermore, 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, per 100 parts by mass of the first liquid crystal polyester.

[0068] The liquid crystal polyester contained in the liquid crystal polyester powder of this embodiment preferably has a flow initiation temperature of 255°C or less, more preferably less than 250°C, and even more preferably 245°C or less, as determined by the method described below. Liquid crystal polyester powder containing liquid crystal polyester exhibiting a flow initiation temperature below the above upper limit has the excellent property of not easily increasing the viscosity of the composition containing the liquid crystal polyester powder.

[0069] The flow initiation temperature of the liquid crystal polyester contained in the liquid crystal polyester powder of this embodiment, as determined by the method described below, may be 220°C or higher, 225°C or higher, or 230°C or higher, from the viewpoint of increasing the mechanical strength of the resulting liquid crystal polyester film. Furthermore, by using liquid crystal polyester with a flow initiation temperature above the lower limit, the resulting film will have high heat resistance.

[0070] An example of the temperature range for the liquid crystal polyester's flow initiation temperature in the liquid crystal polyester powder of this embodiment is that it may be 220°C or more and 255°C or less, 225°C or more and less than 250°C, or 230°C or more and 245°C or less.

[0071] Furthermore, if the liquid crystal polyester powder of the embodiment contains two or more liquid crystal polyester resins with different flow initiation temperatures, the flow initiation temperature of the liquid crystal polyester can be the flow initiation temperature of the mixture of the two or more liquid crystal polyester resins.

[0072] Here, the flow initiation temperature is defined as 9.8 MPa (100 kg / cm²) using a capillary rheometer fitted with a die with an inner diameter of 1 mm and a length of 10 mm. 2 The flow initiation temperature is the temperature at which the melt viscosity reaches 4800 Pa·s (48000 poise) when liquid crystal polyester is extruded from a nozzle at a heating rate of 4°C / min under a load of ). The flow initiation temperature is an index representing the molecular weight of liquid crystal polyester, which is well known in this art (see Naoyuki Koide (ed.), "Synthesis, Molding, and Applications of Liquid Crystalline Polymers," pp. 95-105, CMC, published June 5, 1987). As an apparatus for measuring the flow initiation temperature, for example, the flow characteristic evaluation device "Flow Tester CFT-500D" manufactured by Shimadzu Corporation can be used.

[0073] (Method of manufacturing liquid crystal polyester) Next, an example of a method for manufacturing liquid crystal polyester according to this embodiment will be described.

[0074] The liquid crystal polyester of this embodiment is preferably manufactured by the following acylation and polymerization steps.

[0075] The acylation process is a process in which an acylated product is obtained by acyling the phenolic hydroxyl group of a raw material monomer with a fatty acid anhydride (for example, acetic anhydride).

[0076] In the polymerization step, it is preferable to obtain a liquid crystal polyester by polymerizing the acyl group of the acylated product obtained in the acylation step with the carboxyl group of the acylated product of aromatic dicarboxylic acid and aromatic hydroxycarboxylic acid in a manner that involves transesterification.

[0077] The acylation step and polymerization step may be carried out in the presence of a heterocyclic organic base compound represented by the following formula (5).

[0078] [ka]

[0079] In equation (5) above, R 1 ~R 4 Each of these independently represents a hydrogen atom, a C1-C4 alkyl group, a hydroxymethyl group, a cyano group, a cyanoalkyl group with C1-C4 alkyl groups, a cyanoalkoxy group with C1-C4 alkoxy groups, a carboxyl group, an amino group, an aminoalkyl group with C1-C4, an aminoalkoxy group with C1-C4, a phenyl group, a benzyl group, a phenylpropyl group, or a formyl group.

[0080] The heterocyclic organic base compound in formula (5) above is R 1 is an alkyl group having 1 to 4 carbon atoms, and R 2 ~R 4 Preferably, each of these is an imidazole derivative 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. Furthermore, it can improve the color tone of the film obtained using the liquid crystal polyester composition of this embodiment.

[0081] Among heterocyclic organic base compounds, 1-methylimidazole and 1-ethylimidazole, or both, are particularly preferred due to their availability.

[0082] Furthermore, it is preferable that the amount of heterocyclic organic base compound used be 0.005 to 1 part by mass when the total amount of raw material monomers for the liquid crystal polyester (i.e., aromatic dicarboxylic acid, aromatic diol, and aromatic hydroxycarboxylic acid) is 100 parts by mass. Moreover, from the viewpoint of the color tone of the molded article and productivity, it is more preferable that the amount be 0.05 to 0.5 parts by mass per 100 parts by mass of raw material monomers.

[0083] The heterocyclic organic base compound only needs to be present at some point during the acylation and transesterification reactions. Its addition may occur immediately before the start of the acylation reaction, during the acylation reaction, or between the acylation and transesterification reactions. The resulting liquid crystal polyester has very high melt fluidity and excellent thermal stability.

[0084] The amount of fatty acid anhydride (e.g., acetic anhydride) used should be determined considering the amount of aromatic diol and aromatic hydroxycarboxylic acid used as raw material monomers. Specifically, it is preferable to use an amount of 1.0 to 1.2 equivalents relative to the total amount of phenolic hydroxy groups contained in these raw material monomers, 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.

[0085] When the amount of fatty acid anhydride used is 1.0 equivalent or more relative to the total amount of phenolic hydroxyl groups in the raw material monomers, the acylation reaction proceeds easily, less unreacted raw material monomers remain in the subsequent polymerization step, and as a result, polymerization proceeds efficiently. Furthermore, when the acylation reaction proceeds sufficiently in this way, there is less possibility that unacylated raw material monomers will sublimate and clog the fractional distiller used during polymerization. On the other hand, when the amount of fatty acid anhydride used is 1.2 equivalent or less, the resulting liquid crystal polyester is less likely to be colored.

[0086] The acylation reaction in the acylation step described above is preferably carried out at a temperature range of 130°C to 180°C for 30 minutes to 20 hours, and more preferably at 140°C to 160°C for 1 to 5 hours.

[0087] The aromatic dicarboxylic acid used in the polymerization step described above may be present in the reaction system during the acylation step. That is, the aromatic diol, aromatic hydroxycarboxylic acid, and aromatic dicarboxylic acid may be present in the same reaction system during the acylation step. This is because the carboxyl group and optionally substituted substituents on the aromatic dicarboxylic acid are not affected in any way by the fatty acid anhydride.

[0088] Therefore, the process may involve sequentially carrying out the acylation and polymerization steps after charging the aromatic diol, aromatic hydroxycarboxylic acid, and aromatic dicarboxylic acid into a reactor, or it may involve charging the aromatic diol and aromatic dicarboxylic acid into a reactor, carrying out the acylation step, and then further charging the aromatic dicarboxylic acid into the reactor to carry out the polymerization step. From the viewpoint of simplifying the manufacturing process, the former method is preferred.

[0089] The transesterification reaction in the polymerization step described above is preferably carried out while increasing the temperature from 130°C to 400°C at a heating rate of 0.1 to 50°C / min, and more preferably while increasing the temperature from 150°C to 350°C at a heating rate of 0.3 to 5°C / min.

[0090] Furthermore, when carrying out the transesterification reaction in the polymerization process, it is preferable to evaporate and distill off by-product fatty acids (e.g., acetic acid) and unreacted fatty acid anhydrides (e.g., acetic anhydride) to shift the equilibrium. At this time, by refluxing a portion of the distilled fatty acids and returning them to the reactor, it is also possible to condense or backsublimate the raw material monomers that evaporate or sublimate along with the fatty acids and return them to the reactor.

[0091] In the acylation reaction of the acylation step and the transesterification reaction of the polymerization step, either a batch reactor or a continuous reactor may be used. Regardless of which reactor is used, a liquid crystal polyester suitable for use in this embodiment can be obtained.

[0092] For example, by appropriately adjusting the reaction time in the polymerization process described above, a liquid crystal polyester having a desired flow initiation temperature can be obtained.

[0093] After the polymerization step described above, a step may be performed to increase the molecular weight of the liquid crystal polyester resin obtained in this polymerization step. For example, by cooling the liquid crystal polyester resin obtained in the polymerization step and then grinding it to produce a powdered liquid crystal polyester resin, and then heating this powder, it is possible to increase the molecular weight of the liquid crystal polyester resin.

[0094] Alternatively, the liquid crystal polyester resin may be made into pellets by granulating the powdered liquid crystal polyester resin obtained by cooling and pulverization, and then the molecular weight of the liquid crystal polyester resin may be increased by heating the pellets. In this technical field, the process of increasing molecular weight using these methods is called solid-phase polymerization.

[0095] Solid-phase polymerization is particularly effective as a method for increasing the molecular weight of liquid crystal polyester resins. By increasing the molecular weight of liquid crystal polyester resins through solid-phase polymerization, it is possible to easily obtain liquid crystal polyester resins that satisfy the flow initiation temperature of the liquid crystal polyester according to the embodiment.

[0096] The reaction conditions for the solid-phase polymerization typically involve heat-treating the solid resin under an inert gas atmosphere or reduced pressure for 1 to 20 hours. The polymerization conditions for this solid-phase polymerization can be appropriately optimized after determining the flow initiation temperature of the resin obtained by the melt polymerization. Examples of equipment used for this heat treatment include known dryers, reactors, inert ovens, and electric furnaces.

[0097] Liquid crystal polyesters that satisfy the above-mentioned flow initiation temperature can be easily obtained by appropriately optimizing the structural units that constitute the liquid crystal polyester. In other words, improving the linearity of the molecular chains of the liquid crystal polyester tends to raise its flow initiation temperature.

[0098] For example, structural units derived from terephthalic acid improve the linearity of liquid crystal polyester molecular chains. On the other hand, structural units derived from isophthalic acid improve the flexibility (decreasing linearity) of liquid crystal polyester molecular chains. Therefore, by controlling the copolymerization ratio of terephthalic acid and isophthalic acid, it is possible to obtain liquid crystal polyester with a desired flow initiation temperature.

[0099] When using the above-mentioned liquid crystal polyester mixture, it is preferable that at least one of the liquid crystal polyesters is a polymer obtained by polymerizing raw material monomers containing an aromatic hydroxycarboxylic acid in the presence of an imidazole compound. The liquid crystal polyester obtained in this way has very high fluidity when melted and excellent thermal stability.

[0100] In the liquid crystal polyester powder according to the embodiment, the number average molecular weight of the liquid crystal polyester is preferably 10,000 or less, more preferably 3,000 to 10,000, even more preferably 4,000 to 8,000, and particularly preferably 5,000 to 7,000. When the number average molecular weight of the liquid crystal polyester in the liquid crystal polyester powder is 10,000 or less, it is easy to process it into a film with excellent isotropy. Furthermore, the smaller the number average molecular weight of the liquid crystal polyester, the more likely it is that the thermal conductivity in the thickness direction of the film after heat treatment will improve, which is preferable. When the number average molecular weight of the liquid crystal polyester is above the lower limit mentioned above, the heat resistance of the film after heat treatment will be higher, and the strength and rigidity will also be higher.

[0101] In this specification, "number-average molecular weight" refers to the absolute value measured using a gel permeation chromatograph-multi-angle light scattering photometer.

[0102] (characteristic) In the embodiment, the liquid crystal polyester powder may have primary particles that constitute the liquid crystal polyester powder having a fibril-like form. The liquid crystal polyester powder may have at least a portion of its primary particles having a fibril-like form, or the entire primary particle may have a fibril-like form. Examples of fibril-like forms include those with a fiber diameter (diameter) of preferably 0.1 μm or more and 10 μm or less, more preferably 0.5 μm or more and 5 μm or less, and preferably a fiber length / fiber diameter value of 2 or more.

[0103] The fibrilized nature of liquid crystal polyester powder can be determined, for example, by observing the liquid crystal polyester powder with a scanning electron microscope (SEM). The fiber diameter and fiber length of a fibril can be determined by measuring the diameter and length of 100 fibrils randomly selected from SEM images, and then using the average of these 100 measurements.

[0104] The higher the flow initiation temperature of liquid crystal polyester, the more likely the liquid crystal polyester powder is to have a fibril-like morphology with finer fiber diameters and longer fiber lengths.

[0105] According to the liquid crystal polyester powder of this embodiment, if the flow initiation temperature of the liquid crystal polyester is above the predetermined value mentioned above (for example, 220°C or higher), fibrillation of the liquid crystal polyester powder is favorable, and the fibrils of the liquid crystal polyester powder intertwine appropriately, which is thought to further improve the mechanical strength of the resulting liquid crystal polyester film. Furthermore, if the flow initiation temperature of the liquid crystal polyester is below the predetermined value mentioned above (for example, 255°C or lower), fibrillation of the liquid crystal polyester powder is likely suppressed, making it difficult to increase the viscosity of the composition.

[0106] The liquid crystal polyester powder of the embodiment may contain primary particles having a fibril-like morphology in an amount of 50% to 100%, 60% to 95%, or 70% to 90% relative to the primary particles contained in the liquid crystal polyester powder, based on the number of particles.

[0107] Furthermore, in the method for manufacturing a liquid crystal polyester film or laminate according to the embodiment described later, there is no need to dissolve the liquid crystal polyester powder in a medium, so liquid crystal polyester powder with excellent dielectric properties can be used as a raw material. A liquid crystal polyester film with excellent dielectric properties can be manufactured from liquid crystal polyester powder with excellent dielectric properties. In this specification, "dielectric properties" refers to properties relating to relative permittivity and dielectric loss tangent.

[0108] The liquid crystal polyester powder of the embodiment preferably has a relative permittivity of 3 or less at a frequency of 1 GHz, preferably 2.9 or less, preferably 2.8 or less, more preferably less than 2.8, even more preferably 2.78 or less, and particularly preferably 2.76 or less. Furthermore, the relative permittivity of the liquid crystal polyester powder may be 2.5 or more, 2.6 or more, or 2.7 or more. The upper and lower limits of the relative permittivity value of the liquid crystal polyester powder can be freely combined. An example of the numerical range for the relative permittivity value of the liquid crystal polyester powder is that it may be 2.5 or more and 3 or less, 2.6 or more and 2.78 or less, or 2.7 or more and 2.76 or less.

[0109] The liquid crystal polyester powder of the embodiment preferably has a dielectric loss tangent of 0.005 or less at a frequency of 1 GHz, preferably 0.004 or less, more preferably 0.003 or less, even more preferably 0.0025 or less, and particularly preferably 0.002 or less. Furthermore, the dielectric loss tangent of the liquid crystal polyester powder may be 0.0003 or more, 0.0005 or more, or 0.001 or more. The upper and lower limits of the dielectric loss tangent value for the liquid crystal polyester powder described above can be freely combined. An example of the numerical range for the dielectric loss tangent value for the liquid crystal polyester powder described above is that it may be 0.0003 or more and 0.005 or less, 0.0005 or more and 0.004 or less, 0.001 or more and 0.003 or less, 0.001 or more and 0.0025 or less, or 0.001 or more and 0.002 or less.

[0110] Furthermore, the relative permittivity and dielectric loss tangent of liquid crystal polyester powder at a frequency of 1 GHz can be measured using the capacitance method with an impedance analyzer under the following conditions. A tablet with a diameter of 1 cm and a thickness of 0.5 cm is prepared by melting liquid crystal polyester fine particle powder at a temperature 5°C higher than the melting point measured using a flow tester, and then cooling and solidifying it. The relative permittivity and dielectric loss tangent of the obtained tablet are measured at 1 GHz under the following conditions. ·Measurement method: Capacitive method ·Electrode model: 16453A • Measurement environment: 23℃, 50%RH • Applied voltage: 1V

[0111] Note that the relative permittivity and dielectric loss tangent of the liquid crystal polyester powder in the embodiment may differ from those of a liquid crystal polyester film manufactured using the powder as a raw material. This is thought to be due to differences in the molecular weight of the liquid crystal polyester contained.

[0112] The liquid crystal polyester powder is preferably insoluble in the medium contained in the liquid crystal polyester composition described later, and more preferably insoluble in aprotic solvents. As an example of a liquid crystal polyester powder that is insoluble in the medium, a liquid crystal polyester having structural units represented by the above formulas (1) to (3) can be cited. Whether or not a substance is insoluble in the medium can be confirmed by performing the following test. The following test method describes the case where the medium is an aprotic solvent.

[0113] • Test method Liquid crystal polyester powder (5 parts by weight) is stirred in an aprotic solvent (medium) (95 parts by weight) at 180°C for 6 hours using an anchor blade at 200 rpm, and then cooled to room temperature. Next, the mixture is filtered using a 5 μm mesh membrane filter and a pressurized filter, and the residue on the membrane filter is checked. If no solid material is found, it is considered soluble in the aprotic solvent (medium). If solid material is found, it is considered insoluble in the aprotic solvent (medium). The solid material can be confirmed by microscopic observation.

[0114] (Method for manufacturing liquid crystal polyester powder) The liquid crystal polyester powder of the embodiment is obtained by grinding a liquid crystal polyester resin containing liquid crystal polyester, as described in D 90 A liquid crystal polyester powder with a particle size of 20 μm or less can be obtained.

[0115] The above-mentioned liquid crystal polyester resin may contain components that make up the liquid crystal polyester powder of the embodiment.

[0116] One method for crushing liquid crystal polyester resin is, for example, the D of liquid crystal polyester powder. 90 The liquid crystal polyester powder of this embodiment can be obtained by grinding it using a jet mill or the like so that the particle size becomes 20 μm or less. As a method for controlling the particle size of liquid crystal polyester powder to the aforementioned range, the particle size of the liquid crystal polyester powder can be controlled by changing the rotation speed of the classification rotor, the pressure of the grinding nozzle, the processing speed, etc. Alternatively, after the grinding process, the particles may be classified using a sieve with a mesh opening corresponding to the desired particle size.

[0117] ≪Liquid crystal polyester composition≫ The liquid crystal polyester composition of the embodiment contains a medium and liquid crystal polyester powder. Examples of liquid crystal polyester powder can be found in the section above titled "Liquid Crystal Polyester Powder".

[0118] <medium> The medium contained in the liquid crystal polyester composition of the embodiment is preferably a substance that is in a liquid state at 1 atm (1013.25 hPa) and 25°C. The medium is preferably a volatile component that is a substance that can be volatilized during the formation of the liquid crystal polyester film.

[0119] The medium is preferably a dispersion medium in which the liquid crystal polyester powder is insoluble and which disperses the liquid crystal polyester powder. In the embodiment, the liquid crystal polyester composition is preferably a dispersion in which the liquid crystal polyester powder is insoluble in the medium and dispersed in the liquid medium.

[0120] Here, "dispersion" refers to a state in which the liquid crystal polyester powder is suspended or floating in a dispersion medium, and is a term used to distinguish it from a state in which the liquid crystal polyester powder is dissolved (excluding the state in which the liquid crystal polyester powder is completely dissolved in the liquid crystal polyester composition). There may be non-uniform areas in the distribution of the liquid crystal polyester powder in the composition. The state of the liquid crystal polyester powder in the composition is sufficient to allow the liquid crystal polyester composition to be applied to the support in the liquid crystal polyester film manufacturing method described later.

[0121] Examples of media include aliphatic polyhydric alcohols such as glycerin, neopentyl glycol, ethylene glycol, propylene glycol, butanediol, hexylene glycol, polyethylene glycol, and polypropylene glycol; halogenated hydrocarbons such as dichloromethane, chloroform, 1,1-dichloroethane, 1,2-dichloroethane, 1,1,2,2-tetrachloroethane, 1-chlorobutane, chlorobenzene, and o-dichlorobenzene; halogenated phenols such as p-chlorophenol, pentachlorophenol, and pentafluorophenol; ethers such as diethyl ether, di-(2-chloroethyl) ether, tetrahydrofuran, and 1,4-dioxane; and Examples include ketones such as cetone, cyclohexanone, and isophorone; esters such as ethyl acetate, butyl lactate, and γ-butyrolactone; carbonates such as ethylene carbonate and propylene carbonate; amines such as triethylamine; nitrogen-containing heterocyclic aromatic compounds such as pyridine; nitriles such as acetonitrile and succinonitrile; amides such as N,N-dimethylformamide, N,N-dimethylacetamide, and N-methylpyrrolidone, and urea compounds such as tetramethylurea; nitro compounds such as nitromethane and nitrobenzene; sulfur compounds such as dimethyl sulfoxide and sulfolane; and phosphorus compounds such as hexamethylphosphate and tri-n-butyl phosphate. Two or more of these may be used.

[0122] The medium may be an aprotic solvent. An aprotic solvent is a solvent that contains aprotic compounds. Examples of such aprotic solvents include halogenated solvents such as 1-chlorobutane, chlorobenzene, 1,1-dichloroethane, 1,2-dichloroethane, chloroform, and 1,1,2,2-tetrachloroethane; ether solvents such as diethyl ether, tetrahydrofuran, and 1,4-dioxane; ketone solvents such as acetone and cyclohexanone; ester solvents such as ethyl acetate; lactone solvents such as γ-butyrolactone; carbonate solvents such as ethylene carbonate and propylene carbonate; amine solvents such as triethylamine and pyridine; nitrile solvents such as acetonitrile and succinonitrile; amide solvents such as N,N-dimethylformamide, N,N-dimethylacetamide, tetramethylurea, and N-methylpyrrolidone; nitro solvents such as nitromethane and nitrobenzene; sulfide solvents such as dimethyl sulfoxide and sulfolane; and phosphoric acid solvents such as hexamethylphosphate and tri-n-butyl phosphate.

[0123] The liquid crystal polyester composition of the embodiment may include a medium with a specific gravity of 0.90 or higher as a medium with excellent dispersibility for liquid crystal polyester powder. In this specification, the "specific gravity" of a medium refers to the specific gravity measured in accordance with JIS Z 8804, with water as the reference substance. Here, specific gravity is defined as the density of the sample liquid divided by the density of water at a pressure of 101325 Pa (1 atmosphere). The liquid crystal polyester composition of the embodiment preferably contains a medium with a specific gravity of 0.90 or higher, more preferably a medium with a specific gravity of 0.95 or higher, even more preferably a medium with a specific gravity of 1.03 or higher, particularly preferably a medium with a specific gravity of 1.1 or higher, and especially preferably a medium with a specific gravity of 1.3 or higher. When the specific gravity of the medium is above the above lower limit, the dispersibility of the liquid crystal polyester powder is excellent. The upper limit of the specific gravity mentioned above may be, for example, 1.84 or less. The liquid crystal polyester composition of the embodiment may contain a medium with a specific gravity of 1.84 or less, a medium with a specific gravity of 1.68 or less, a medium with a specific gravity of 1.58 or less, or a medium with a specific gravity of 1.48 or less. If the specific gravity of the medium is below the above upper limit, the liquid crystal polyester powder will not float on the surface of the liquid medium, which would make dispersion difficult. The upper and lower limits of the specific gravity values ​​of the above-mentioned media can be freely combined. As an example of the numerical range of the specific gravity values ​​of the above-mentioned media, the liquid crystal polyester composition of the embodiment may include media with a specific gravity of 0.90 or more and 1.84 or less, media with a specific gravity of 0.95 or more and 1.68 or less, media with a specific gravity of 1.03 or more and 1.58 or less, and media with a specific gravity of 1.1 or more and 1.48 or less.

[0124] The ratio of liquid crystal polyester powder content to the total mass of the liquid crystal polyester composition of the embodiment is preferably 1 to 40% by mass, more preferably 5 to 30% by mass, and even more preferably 7 to 20% by mass.

[0125] The ratio of the media content to the total mass of the liquid crystal polyester composition in the embodiment is preferably 50 to 99% by mass, more preferably 60 to 95% by mass, and even more preferably 70 to 90% by mass.

[0126] An example of the liquid crystal polyester composition of the embodiment is, relative to the total mass (100% by mass) of the liquid crystal polyester composition, A liquid crystal polyester composition is preferred in which the liquid crystal polyester powder content is 1 to 40% by mass and the medium content is 50 to 99% by mass. A liquid crystal polyester composition having a liquid crystal polyester powder content of 5 to 30% by mass and a medium content of 60 to 95% by mass is more preferable. A liquid crystal polyester composition is more preferably one in which the liquid crystal polyester powder content is 7 to 20% by mass and the medium content is 70 to 90% by mass.

[0127] Another example of the liquid crystal polyester composition of the embodiment is, with respect to the total mass (100% by mass) of the liquid crystal polyester composition, A liquid crystal polyester composition is preferred in which the liquid crystal polyester powder content is 1 to 40% by mass and the medium content is 60 to 99% by mass. A liquid crystal polyester composition having a liquid crystal polyester powder content of 5 to 30% by mass and a medium content of 70 to 95% by mass is more preferable. A liquid crystal polyester composition is more preferably one in which the liquid crystal polyester powder content is 7 to 20% by mass and the medium content is 80 to 93% by mass.

[0128] The ratio of solid content to the total mass of the liquid crystal polyester composition of the embodiment is preferably 1 to 50% by mass, more preferably 5 to 40% by mass, and even more preferably 10 to 30% by mass.

[0129] An example of the liquid crystal polyester composition of the embodiment is, relative to the total mass (100% by mass) of the liquid crystal polyester composition, A liquid crystal polyester composition is preferred in which the solid content is 1 to 50% by mass and the medium content is 50 to 99% by mass. A liquid crystal polyester composition having a solid content of 5 to 40% by mass and a medium content of 60 to 95% by mass is more preferable. A liquid crystal polyester composition having a solid content of 10 to 30% by mass and a medium content of 70 to 90% by mass is even more preferred.

[0130] The ratio of liquid crystal polyester powder content to the total mass (100% by mass) of solids contained in the liquid crystal polyester composition may, for example, be 30 to 100% by mass, 40 to 90% by mass, or 50 to 80% by mass. The term "solids" in the liquid crystal polyester composition of the embodiment refers to non-volatile components excluding substances that can volatilize during the formation of the liquid crystal polyester film, etc.

[0131] The ratio of the liquid crystal polyester powder content to the total mass (100% by mass) of the media-insoluble components contained in the liquid crystal polyester composition may be 50-100% by mass, 60-99% by mass, or 80-95% by mass.

[0132] In addition to the medium and liquid crystal polyester powder, the liquid crystal polyester composition may optionally contain one or more other components such as fillers, additives, or other resins that are not liquid crystal polyester powder.

[0133] Examples of fillers include inorganic fillers such as silica, alumina, titanium oxide, barium titanate, strontium titanate, aluminum hydroxide, and calcium carbonate; and organic fillers such as cured epoxy resin, crosslinked benzoguanamine resin, and crosslinked acrylic resin. The content of these fillers may be 0 parts by mass or less, and is preferably 100 parts by mass or less, per 100 parts by mass of liquid crystal polyester.

[0134] Examples of additives include leveling agents, defoaming agents, antioxidants, ultraviolet absorbers, flame retardants, and colorants. The amount of these additives may be 0, and preferably 5 parts by mass or less, per 100 parts by mass of liquid crystal polyester.

[0135] Examples of other resins besides liquid crystal polyester include thermoplastic resins other than liquid crystal polyester such as polypropylene, polyamide, polyesters other than liquid crystal polyester, polyphenylene sulfide, polyether ketone, polycarbonate, polyether sulfone, polyphenylene ether and its modified products, and polyetherimide; elastomers such as copolymers of glycidyl methacrylate and polyethylene; and thermosetting resins such as phenolic resins, epoxy resins, polyimide resins, and cyanate resins. Fluororesins are also preferred examples of other resins. "Fluororesin" refers to resins containing fluorine atoms in their molecules, and includes polymers having structural units containing fluorine atoms. The content of other resins may be 0, and preferably 20 parts by mass or less, per 100 parts by mass of liquid crystal polyester powder. It is preferable that the other resins are soluble in the medium.

[0136] The other resins mentioned above may be any resin that does not fall under the category of liquid crystal polyester powder, and may be liquid crystal polyester. The liquid crystal polyester is preferably soluble in the medium, and more preferably soluble in an aprotic solvent.

[0137] The liquid crystal polyester composition of the embodiment may contain a medium, a liquid crystal polyester powder of the embodiment that is insoluble in the medium, and a liquid crystal polyester that is soluble in the medium. In this case, the content of liquid crystal polyester soluble in the medium relative to 100 parts by mass of liquid crystal polyester powder insoluble in the medium in the liquid crystal polyester composition may be 10 to 200 parts by mass, 20 to 150 parts by mass, or 30 to 100 parts by mass.

[0138] An example of the liquid crystal polyester composition of the embodiment is, relative to the total mass (100% by mass) of the liquid crystal polyester composition, A liquid crystal polyester composition is preferred in which the content of the medium is 50 to 98% by mass, the content of liquid crystal polyester soluble in the medium is 1 to 40% by mass, and the content of liquid crystal polyester powder insoluble in the medium is 1 to 40% by mass. A liquid crystal polyester composition is more preferably one in which the content of the medium is 60 to 90% by mass, the content of liquid crystal polyester soluble in the medium is 5 to 30% by mass, and the content of liquid crystal polyester powder insoluble in the medium is 5 to 30% by mass. A liquid crystal polyester composition is more preferably one in which the content of the medium is 70 to 90% by mass, the content of liquid crystal polyester soluble in the medium is 5 to 15% by mass, and the content of liquid crystal polyester powder insoluble in the medium is 5 to 15% by mass.

[0139] In a liquid crystal polyester composition, it is preferable that the medium in which the liquid crystal polyester soluble in the medium is dissolved is in a liquid state at 1 atm (1013.25 hPa) and 25°C.

[0140] Furthermore, whether or not liquid crystal polyester is soluble in a medium can be confirmed by performing the following test.

[0141] • Test method Liquid crystal polyester powder (5 parts by mass) is stirred in a medium (95 parts by mass) at 180°C for 6 hours using an anchor blade at 200 rpm, and then cooled to room temperature (23°C). Next, the mixture is filtered using a 5 μm mesh membrane filter and a pressurized filter, and the residue on the membrane filter is checked. If no solid material is found, the mixture is considered soluble in the medium. If solid material is found, the mixture is considered insoluble in the medium. Solid material can be identified by microscopic observation.

[0142] Below, as an example of a liquid crystal polyester soluble in a medium, we will describe liquid crystal polyester (X) soluble in aprotic solvents.

[0143] The liquid crystal polyester (X) (hereinafter also referred to as component (X)) preferably contains structural units represented by the following formulas (X1), (X2), and (X3).

[0144] As one aspect, the content of the structural unit represented by formula (X1) is 30-80 mol% of the total content of all structural units constituting component (X), the content of the structural unit represented by formula (X2) is 35-10 mol%, and the content of the structural unit represented by formula (X3) is 35-10 mol%. However, the total content of the structural units represented by formula (X1), formula (X2), and formula (X3) shall not exceed 100 mol%. (X1) -O-Ar1'-CO- (X2) -CO-Ar2'-CO- (X3) ―X-Ar3'-Y- (In X1-X3, Ar1' represents a 1,4-phenylene group, a 2,6-naphthylene group, or a 4,4'-biphenylene group. Ar2' represents a 1,4-phenylene group, a 1,3-phenylene group, or a 2,6-naphthylene group. Ar3' represents a 1,4-phenylene group or a 1,3-phenylene group. X is -NH-, and Y is -O- or -NH-.)

[0145] Structural unit (X1) is a structural unit derived from an aromatic hydroxycarboxylic acid, structural unit (X2) is a structural unit derived from an aromatic dicarboxylic acid, and structural unit (X3) is a structural unit derived from an aromatic diamine or an aromatic amine having a phenolic hydroxyl group. Component (X) may use esters or amide-forming derivatives of the above-mentioned structural units instead of the above-mentioned structural units.

[0146] In this embodiment, it is preferable that Ar1' is a 2,6-naphthylene group, Ar2' is a 1,3-phenylene group, Ar3' is a 1,4-phenylene group, and Y is -O-.

[0147] Examples of ester-forming derivatives of carboxylic acids include those in which the carboxyl group is a highly reactive derivative such as an acid chloride or acid anhydride that promotes the reaction of producing polyester, and those in which the carboxyl group forms esters with alcohols or ethylene glycol, etc., that produce polyester through transesterification reactions. Examples of ester-forming derivatives of phenolic hydroxyl groups include those in which the phenolic hydroxyl group forms an ester with carboxylic acids. Examples of amide-forming derivatives of amino groups include those in which the amino group forms an amide with carboxylic acids.

[0148] Examples of structural units of component (X) used in this embodiment include, but are not limited to, the following.

[0149] Examples of structural units represented by formula (X1) include structural units derived from 4-hydroxybenzoic acid, 6-hydroxy-2-naphthoic acid, or 4'-hydroxy-4-biphenylcarboxylic acid, and two or more of these structural units may be included in the total structural units. Among these structural units, it is preferable to use component (X) which contains a structural unit derived from 6-hydroxy-2-naphthoic acid. The content of structural unit (X1) is preferably 30 mol% to 80 mol%, more preferably 40 mol% to 70 mol%, and more preferably 45 mol% to 65 mol%, relative to the total content of structural units constituting component (X). A high concentration of structural units (X1) tends to significantly reduce solubility in the solvent, while too little tends to result in a lack of liquid crystalline properties. In other words, when the content of structural units (X1) is within the above range, solubility in the solvent is good, and liquid crystalline properties are easily observed.

[0150] Examples of structural units represented by formula (X2) include structural units derived from terephthalic acid, isophthalic acid, or 2,6-naphthalenedicarboxylic acid, and two or more of these structural units may be included in the total number of structural units. Among these structural units, it is preferable to use a liquid crystal polyester containing structural units derived from isophthalic acid from the viewpoint of solubility in solvents. The content of structural unit (X2) is preferably 10 mol% to 35 mol%, more preferably 15 mol% to 30 mol%, and particularly preferably 17.5 mol% to 27.5 mol%, relative to the total content of structural units constituting component (X). Too much structural unit (X2) tends to reduce liquid crystalline properties, while too little tends to reduce solubility in the solvent. In other words, when the content of structural unit (X2) is within the above range, both liquid crystalline properties and solubility in the solvent are good.

[0151] Examples of structural units represented by formula (X3) include structural units derived from acetaminophen, 3-aminophenol, 4-aminophenol, 1,4-phenylenediamine, or 1,3-phenylenediamine, and two or more of these structural units may be included in the total number of structural units. Among these structural units, it is preferable to use a liquid crystal polyester containing structural units derived from 4-aminophenol from the viewpoint of reactivity.

[0152] The content of structural unit (X3) is preferably 10 mol% to 35 mol%, more preferably 15 mol% to 30 mol%, and particularly preferably 17.5 mol% to 27.5 mol%, relative to the total content of structural units constituting component (X). Too much structural unit (3) tends to reduce liquid crystalline properties, while too little tends to reduce solubility in the solvent. In other words, when the content of structural unit (X3) is within the above range, both liquid crystalline properties and solubility in the solvent are good.

[0153] It is preferable that structural unit (X3) is used in substantially equal amounts to structural unit (X2), but the degree of polymerization of the liquid crystal polyester can also be controlled by setting the content of structural unit (X3) to -10 to +10 mol% relative to the content of structural unit (X2).

[0154] Liquid crystal polyester soluble in a medium can be produced by the same method as illustrated in the above embodiment as a method for producing liquid crystal polyester powder. If the liquid crystal polyester (X) is in powder form, D 50 The diameter is preferably 100 to 2000 μm. 50 This can be measured by a dry sieving method (for example, RPS-105 manufactured by Seishin Corporation).

[0155] One aspect is that the content of component (X) is preferably 5 to 10% by mass relative to the total mass of the liquid crystal polyester composition.

[0156] According to the liquid crystal polyester composition containing the liquid crystal polyester powder of the embodiment, the liquid crystal polyester powder is D 90 Because the thickness is 20 μm or less, it is possible to manufacture liquid crystal polyester films with excellent mechanical strength with high efficiency.

[0157] The liquid crystal polyester composition of the embodiment can be provided as a liquid crystal polyester composition for film, used in the method for manufacturing the liquid crystal polyester film of the embodiment.

[0158] Furthermore, according to the embodiment of the liquid crystal polyester composition in which the liquid crystal polyester powder is insoluble in the medium and the liquid crystal polyester powder is dispersed in the liquid medium, a liquid crystal polyester film with excellent dielectric properties can be easily manufactured. While using liquid crystal polyester with enhanced solubility in solvents is advantageous in that it allows for the formation of films with isotropic molecular orientation, it can sometimes lead to a decrease in dielectric properties, for example, due to increased polarity. On the other hand, the liquid crystal polyester composition of the embodiment can easily improve the dielectric properties of the film by including liquid crystal polyester powder that is insoluble in the medium.

[0159] ≪Method for manufacturing liquid crystal polyester composition≫ The liquid crystal polyester composition of the embodiment can be obtained by mixing the medium, liquid crystal polyester powder, and other components used as needed, either all at once or in an appropriate order.

[0160] Examples of the medium and liquid crystal polyester powder can be found in the sections described above under "Liquid Crystal Polyester Powder" and "Liquid Crystal Polyester Composition."

[0161] One embodiment includes mixing a medium with liquid crystal polyester powder, wherein the liquid crystal polyester powder has a particle size D such that the cumulative volume ratio from the smallest particles is 90% in the volume-based cumulative particle size distribution curve obtained by laser diffraction / scattering particle size distribution measurement. 90 When this is the case, the above D 90 The present invention provides a method for producing a liquid crystal polyester composition in which the particle size is 20 μm or less.

[0162] ≪Method for manufacturing liquid crystal polyester film≫ The method for producing the liquid crystal polyester film of the embodiment includes applying the liquid crystal polyester composition of the embodiment onto a support, and then heat-treating it to obtain a liquid crystal polyester film containing liquid crystal polyester.

[0163] Examples of liquid crystal polyester compositions include those described in the section above titled "Liquid Crystal Polyester Compositions."

[0164] The manufacturing method may include the following steps: A step (coating step) in which a liquid crystal polyester composition according to the embodiment is applied to a support to form a precursor of a liquid crystal polyester film on the support. A step of obtaining a liquid crystal polyester film by heat-treating the precursor of the liquid crystal polyester film (heat treatment step).

[0165] In the method for manufacturing a liquid crystal polyester film, the coating step may include a step of coating the liquid crystal polyester composition of the embodiment onto a support, and then removing the medium from the coated liquid crystal polyester composition (drying step). In other words, the method for manufacturing the liquid crystal polyester film of the embodiment may include applying the liquid crystal polyester composition of the embodiment onto a support, removing the medium from the applied liquid crystal polyester composition, and heat-treating it to obtain a liquid crystal polyester film containing liquid crystal polyester.

[0166] Furthermore, the method for manufacturing a liquid crystal polyester film may also include a step of separating the support from the laminate in which the support and the liquid crystal polyester film are laminated (separation step). However, since the liquid crystal polyester film can be suitably used as a film for electronic components even when formed on the support as a laminate, the separation step is not an essential step in the manufacturing process of the liquid crystal polyester film.

[0167] An example of a method for manufacturing a liquid crystal polyester film according to an embodiment will be described below with reference to the drawings.

[0168] Figures 1A to 1D are schematic diagrams showing an example of the manufacturing process of the liquid crystal polyester film and laminate according to the embodiment. First, the liquid crystal polyester composition 30 is applied onto the support 12 (Figure 1A, application process). The liquid crystal polyester composition 30 includes liquid crystal polyester powder 1, a medium 3, and a resin 4 (a resin not corresponding to the liquid crystal polyester powder) dissolved in the medium. The liquid crystal polyester composition can be applied to the support by methods such as roller coating, dip coating, spray coating, spinner coating, curtain coating, slot coating, and screen printing, and a method that allows for a smooth and uniform application on the support can be appropriately selected. In addition, to homogenize the distribution of the liquid crystal polyester powder, the liquid crystal polyester composition may be stirred before application.

[0169] The support 12 is preferably in the shape of a plate, sheet, or film, and examples include a glass plate, a resin film, or a metal foil. Among these, a resin film or a metal foil is preferred, and copper foil is particularly preferred because it has excellent heat resistance, is easy to coat with the liquid crystal polyester composition, and is easy to remove from the liquid crystal polyester film. Examples of resin films include polyimide (PI) films. Examples of commercially available products include Ube Industries, Ltd.'s "Yupirex S" and "Yupirex R", Toray DuPont Co., Ltd.'s "Kapton", and SKC Kolon PI's "IF30", "IF70", and "LV300". The thickness of the resin film is preferably 25 μm to 75 μm, more preferably 50 μm to 75 μm. The thickness of the metal foil is preferably 3 μm to 75 μm, more preferably 5 μm to 30 μm, and even more preferably 10 μm to 25 μm.

[0170] Next, the medium 3 is removed from the liquid crystal polyester composition 30 coated on the support 12 (Drying step, Figure 1B) to obtain the liquid crystal polyester film precursor 40 to be heat-treated. Note that the medium 3 does not need to be completely removed from the liquid crystal polyester composition; some of the medium contained in the liquid crystal polyester composition may be removed, or all of the medium may be removed. Also, typically, the components of the resin 4 dissolved in the medium are not removed. The proportion of the medium contained in the liquid crystal polyester film precursor 40 is preferably 50% by mass or less, more preferably 3% by mass or more and 12% by mass or less, and even more preferably 5% by mass or more and 10% by mass or less, based on the total mass of the liquid crystal polyester film precursor. By having a medium content in the liquid crystal polyester film precursor above the lower limit, the risk of a decrease in the thermal conductivity of the liquid crystal polyester film is reduced. Furthermore, by having a medium content in the liquid crystal polyester film precursor below the upper limit, the risk of a deterioration in the appearance of the liquid crystal polyester film due to foaming during heat treatment is reduced.

[0171] The removal of the medium is preferably carried out by evaporation, and methods for this include heating, reduced pressure, and ventilation, which may be combined. The removal of the medium may be carried out in a continuous or single-wafer manner. From the viewpoint of productivity and operability, the removal of the medium is preferably carried out by continuous heating, and more preferably by continuous heating with ventilation. The removal temperature of the medium is preferably below the melting point of the liquid crystal polyester powder, for example, 40°C to 200°C, and preferably 60°C to 200°C. The time for removal of the medium is, for example, 0.2 hours to 12 hours, and preferably 0.5 hours to 8 hours.

[0172] The laminate precursor 22 having the support 12 and the liquid crystal polyester film precursor 40 is heat-treated to obtain a laminate 20 having the support 12 and the liquid crystal polyester film 10 (a film formed by heat-treating the liquid crystal polyester film precursor 40) (Figure 1C: Heat treatment process). At this time, a liquid crystal polyester film 10 formed on the support is obtained. Heat treatment may further advance the polymerization reaction (solid-phase polymerization) of the liquid crystal polyester contained in the liquid crystal polyester film precursor. Heat treatment conditions include, for example, raising the temperature from -50°C (the boiling point of the medium) to the heat treatment temperature, and then performing heat treatment at a temperature above the melting point of the liquid crystal polyester. During this heating process, the polymerization reaction of the liquid crystal polyester may proceed due to heating. However, by increasing the heating rate until the heat treatment temperature is reached, the increase in the molecular weight of the liquid crystal polyester in the liquid crystal polyester powder can be suppressed to some extent, resulting in better melting of the liquid crystal polyester powder and easy acquisition of high-quality films. The heating rate from the boiling point of the solvent, -50°C, to the heat treatment temperature is preferably 3°C / min or more, and more preferably 5°C / min or more. The heat treatment temperature is preferably above the melting point of the liquid crystal polyester, more preferably higher than the melting point of the liquid crystal polyester, and even more preferably 5°C or higher than the melting point of the liquid crystal polyester. The heat treatment temperature can be appropriately determined depending on the type of liquid crystal polyester, but as an example, 230°C to 400°C is preferred, 300°C to 380°C is more preferred, and 320°C to 350°C is even more preferred. By performing heat treatment at a temperature higher than the melting point of the liquid crystal polyester, the liquid crystal polyester powder melts well, and a high-quality liquid crystal polyester film can be formed. The melting of the liquid crystal polyester powder can be confirmed by the transparency of the liquid crystal polyester film precursor 40. The boiling point of the medium referred to here is the boiling point at the pressure during heating. Furthermore, if heating of the laminate precursor 22 is started below -50°C (the boiling point of the medium), the heating rate should be determined within the range from when it reaches -50°C (the boiling point of the medium) to when it reaches the heat treatment temperature. The time it takes to reach -50°C (the boiling point of the medium) is arbitrary. The time after reaching the heat treatment temperature should be considered as the heat treatment time. The heat treatment time may be, for example, 0.5 hours or more, 1 hour to 24 hours or less, or 3 hours to 12 hours or less.

[0173] For example, the heat treatment can be performed at a heat treatment temperature of 230°C to 400°C for a heat treatment time of 0.5 hours or more.

[0174] The heat treatment, like the removal of the media, may be carried out in a continuous or single-wafer manner. However, from the standpoint of productivity and ease of operation, it is preferable to carry it out in a continuous manner, and it is even more preferable to carry it out in a continuous manner immediately following the removal of the media.

[0175] Next, the liquid crystal polyester film 10 can be obtained as a single-layer film by separating it from the laminate 20 having the support 12 and the liquid crystal polyester film 10 (Figure 1D Separation process). When a glass plate is used as the support 12, the liquid crystal polyester film 10 is preferably separated from the laminate 20 by peeling it off. When a resin film is used as the support 12, the separation is preferably performed by peeling the resin film or liquid crystal polyester film 10 off the laminate 20. When a metal foil is used as the support 12, the separation is preferably performed by etching and removing the metal foil from the laminate 20. When a resin film, especially a polyimide film, is used as the support, the polyimide film or liquid crystal polyester film is easily peeled off from the laminate 20, and a liquid crystal polyester film with a good appearance can be obtained. When a metal foil is used as the support, the laminate 20 may be used as a metal-clad laminate for printed circuit boards without separating the liquid crystal polyester film from the laminate 20.

[0176] According to the method for manufacturing a liquid crystal polyester film of the embodiment, the liquid crystal polyester powder is D 90 Having a thickness of 20 μm or less enables the highly efficient production of liquid crystal polyester films with excellent mechanical strength.

[0177] Furthermore, in the film manufacturing method of the embodiment, the degree of fibrillation of the liquid crystal polyester powder can be appropriately adjusted by setting the flow start temperature of the liquid crystal polyester to a value above, for example, the lower limit (220°C or higher). The fibrils of the liquid crystal polyester powder intertwine appropriately, and this also effectively increases the mechanical strength of the manufactured film.

[0178] According to the method for manufacturing a liquid crystal polyester film of this embodiment, the liquid crystal polyester powder may be insoluble in the medium, and a liquid crystal polyester film with excellent isotropy can be easily obtained.

[0179] Furthermore, according to the method for manufacturing a liquid crystal polyester film of the embodiment, by using a liquid crystal polyester composition of the embodiment in which the liquid crystal polyester powder is insoluble in the medium and the liquid crystal polyester powder is dispersed in the liquid medium, a liquid crystal polyester film with excellent dielectric properties can be easily manufactured.

[0180] ≪Method for manufacturing laminates≫ The method for manufacturing the laminate of the embodiment includes applying the liquid crystal polyester composition of the embodiment onto a support, heat-treating it to form a liquid crystal polyester film containing liquid crystal polyester, thereby obtaining a laminate comprising the support and the liquid crystal polyester film.

[0181] The manufacturing method may include the following steps: A step (coating step) in which a liquid crystal polyester composition according to the embodiment is applied to a support to form a liquid crystal polyester film precursor on the support. A step of heat-treating the liquid crystal polyester film precursor to obtain a laminate comprising the support and the liquid crystal polyester film (heat treatment step).

[0182] Similar to the method for manufacturing the liquid crystal polyester film described above, the coating step in the method for manufacturing the laminate may include a step of coating the liquid crystal polyester composition of the embodiment onto a support, and then removing the medium from the coated liquid crystal polyester composition (drying step). In other words, the method for manufacturing the laminate of the embodiment may include applying the liquid crystal polyester composition of the embodiment onto a support, removing the medium from the applied liquid crystal polyester composition, and heat-treating it to form a liquid crystal polyester film containing liquid crystal polyester, thereby obtaining a laminate comprising the support and the liquid crystal polyester film.

[0183] Figures 1A to 1D are schematic diagrams showing an example of the manufacturing process for the liquid crystal polyester film and laminate of the embodiment. The manufacturing method for the laminate illustrated in Figures 1A to 1C is the same as described in the above-mentioned "Method for Manufacturing Liquid Crystal Polyester Film," except that the separation step (Figure 1D) is not performed, so the explanation is omitted.

[0184] According to the manufacturing method of the embodiment, it is possible to manufacture a laminate having the liquid crystal polyester film of the embodiment.

[0185] <Liquid crystal polyester film> Figure 2 is a schematic diagram showing the configuration of the liquid crystal polyester film 11 of the embodiment.

[0186] With liquid crystal polyester powder, it is possible to manufacture a liquid crystal polyester film with good mechanical strength from a composition containing the liquid crystal polyester powder. Tensile strength and tensile strain values ​​can be used as indicators of the mechanical strength of the liquid crystal polyester film.

[0187] The liquid crystal polyester film of the embodiment (hereinafter sometimes simply referred to as "film") may have a tensile strength value determined in accordance with JIS K7161 that is, for example, 120 MPa or more, 120 MPa to 200 MPa, or 130 MPa to 160 MPa.

[0188] The liquid crystal polyester film of the embodiment may have a tensile strength strain value determined in accordance with JIS K7161 that is, for example, 10% or more, 11% to 20%, or 13% to 15%.

[0189] The tensile strength and tensile strain values ​​of liquid crystal polyester film can be obtained by the following method. Tensile strength and tensile strain are measured on a single-layer liquid crystal polyester film. For example, if copper foil is laminated on one side of the liquid crystal polyester film, the copper foil is etched off using a ferric chloride solution or the like to obtain a single-layer liquid crystal polyester film. The single-layer liquid crystal polyester film is cut into a dumbbell-shaped No. 3 test piece (parallel section width 5 mm, length 20 mm) according to JIS K6251, and a tensile test is performed using a tensile testing machine (e.g., Shimadzu Autograph AG-IS) in accordance with JIS K7161 at a tensile speed of 5 mm / min to determine the tensile strength (Pa) and tensile strain (%) of the liquid crystal polyester film at 23°C and 50% RH humidity.

[0190] The relative permittivity of the film in this embodiment may be 3 or less at a frequency of 1 GHz, preferably 2.9 or less, more preferably 2.8 or less, even more preferably 2.7 or less, and particularly preferably 2.6 or less. Furthermore, the relative permittivity of the film may be 2.3 or more, 2.4 or more, or 2.5 or more. Examples of the numerical range for the relative permittivity of the above film include 2.3 to 3, 2.4 to 2.9, 2.5 to 2.8, 2.5 to 2.7, and 2.5 to 2.6.

[0191] The film of the embodiment preferably has a dielectric loss tangent of 0.005 or less at a frequency of 1 GHz, preferably 0.004 or less, more preferably 0.003 or less, even more preferably 0.002 or less, and particularly preferably 0.001 or less. The dielectric loss tangent of the liquid crystal polyester film may be 0.0003 or more, 0.0005 or more, or 0.0007 or more. An example of the numerical range for the dielectric loss tangent value of the above film is that it may be 0.0003 or more and 0.005 or less, 0.0005 or more and 0.004 or less, 0.0007 or more and 0.003 or less, 0.0007 or more and 0.002 or less, or 0.0007 or more and 0.001 or less. Furthermore, the relative permittivity and dielectric loss tangent of the film at a frequency of 1 GHz can be measured using the capacitance method with an impedance analyzer under the following conditions. A tablet with a diameter of 1 cm and a thickness of 0.5 cm is prepared by melting the film at 350°C using a flow tester and then cooling and solidifying it. The relative permittivity and dielectric loss tangent of the obtained tablet are measured at 1 GHz under the following conditions. ·Measurement method: Capacitive method ·Electrode model: 16453A • Measurement environment: 23℃, 50%RH • Applied voltage: 1V

[0192] As an example of the liquid crystal polyester film of the embodiment, we will illustrate a film containing liquid crystal polyester, having a relative permittivity of 3 or less at a frequency of 1 GHz, and a dielectric loss tangent of 0.005 or less at a frequency of 1 GHz.

[0193] The film of the embodiment preferably has a molecular orientation degree (MOR) value measured by a microwave orientation meter in the range of 1 to 1.3, more preferably in the range of 1 to 1.1, more preferably in the range of 1 to 1.08, even more preferably in the range of 1 to 1.06, and particularly preferably in the range of 1 to 1.04.

[0194] The degree of molecular orientation (MOR) is measured using a microwave molecular orientometer (e.g., MOA-5012A, manufactured by Oji Instruments Co., Ltd.). A microwave molecular orientometer is a device that utilizes the fact that the transmission intensity of microwaves differs depending on the orientation of the molecules, with the transmission intensity differing in the direction perpendicular to the orientation. Specifically, while rotating the sample, microwaves with a constant frequency (12 GHz is used) are irradiated, and the intensity of the transmitted microwaves, which changes according to the molecular orientation, is measured. The ratio of the maximum value to the minimum value is defined as the MOR. The interaction between the microwave electric field with a constant frequency and the dipoles that make up the molecules is related to the dot product of their vectors. Due to the anisotropy of the dielectric constant of the sample, the microwave intensity changes depending on the angle at which the sample is positioned, making it possible to determine the degree of orientation.

[0195] The linear expansion coefficient of the film in the embodiment is preferably 85 ppm / °C or less, more preferably 50 ppm / °C or less, even more preferably 40 ppm / °C or less, and particularly preferably 30 ppm / °C or less, as determined in a temperature range of 50 to 100°C under a heating rate of 5°C / min. The lower limit of the linear expansion coefficient is not particularly limited, but for example, it is 0 ppm / °C or higher. Furthermore, for example, when copper foil and film are laminated, since the linear expansion coefficient of copper foil is 18 ppm / °C, it is preferable that the linear expansion coefficient of the film in the embodiment be close to that value. In other words, the linear expansion coefficient of the film in the embodiment is preferably 0 ppm / °C or more and 50 ppm / °C or less, more preferably 10 ppm / °C or more and 40 ppm / °C or less, and even more preferably 20 ppm / °C or more and 30 ppm / °C or less. If the linear expansion coefficient differs depending on the direction or part of the film, the higher value shall be adopted as the linear expansion coefficient of the film. The coefficient of linear expansion of the film can be measured using a thermomechanical analyzer (for example, Rigaku Corporation, model: TMA8310). Films of embodiments that satisfy the above numerical range have a low coefficient of linear expansion and high dimensional stability.

[0196] A film with excellent isotropy exhibits a small difference in the coefficient of linear expansion depending on the measurement direction. In the embodiment, the film preferably has a linear expansion coefficient of 2 ppm / °C or less, and more preferably 1 ppm / °C or less, where the difference between the linear expansion coefficient of MD and the linear expansion coefficient of TD (MD-TD if MD > TD, and TD-MD if TD > MD) is 2 ppm / °C or less. In a film manufactured by the casting method, MD refers to the coating direction of the dispersion. As shown in the calculation of the difference in linear expansion coefficients above, in practice, it is sufficient to know the linear expansion coefficients in different directions. Therefore, if the MD and TD of the film are unknown, the direction should be set such that the difference in linear expansion coefficients in each direction is maximized when any direction of the film is designated as MD and the direction intersecting it at 90° is designated as TD. The film of the embodiment that satisfies the above numerical range exhibits excellent isotropy in linear expansion and high dimensional stability in the longitudinal and transverse directions.

[0197] The film of the embodiment preferably has no holes or through-holes, as this gives it a suitable appearance for use as a film for electronic components. If it has holes or through-holes, there is a possibility that the plating solution may seep into the holes or through-holes during the plating process. The liquid crystal polyester film manufactured using the liquid crystal polyester powder according to the embodiment is of high quality, having a suitable thickness for use as a film for electronic components while suppressing the occurrence of holes or through-holes.

[0198] The thickness of the film in the embodiment is not particularly limited, but a suitable thickness for an electronic component film is preferably 5 to 50 μm, more preferably 7 to 40 μm, even more preferably 10 to 33 μm, and particularly preferably 15 to 20 μm. In this specification, "thickness" refers to the average value obtained by measuring the thickness at 10 randomly selected locations in accordance with the JIS standard (K7130-1992).

[0199] By selecting a raw material with excellent dielectric properties from among any liquid crystal polyester, a film with excellent dielectric properties can be obtained. The liquid crystal polyester content relative to 100% of the total mass of the film in the embodiment may be 50 to 100% by mass, or 80 to 95% by mass.

[0200] Films that meet the above specifications have suitable quality for use as films for electronic components. The quality criteria include the relative permittivity and dielectric loss tangent mentioned above, as well as other factors such as molecular orientation (isotropy of the film), tensile strength, tensile strain, thickness, and appearance (presence or absence of holes or through-holes).

[0201] The method for manufacturing the film of the embodiment is not particularly limited, but the film of the embodiment can be manufactured by the method described above in "Method for Manufacturing Crystalline Polyester Film". For example, the relative permittivity and dielectric loss tangent values ​​of a film can be controlled by the type of liquid crystal polyester used. Also, for example, the degree of isotropy of a film can be controlled by the film manufacturing method.

[0202] The film of this embodiment can be suitably used as a film for electronic components such as printed circuit boards. The film of this embodiment can be provided as a substrate (e.g., a flexible substrate), a laminate (e.g., a flexible copper-clad laminate), a printed circuit board, a printed wiring board, a printed circuit board, etc., which incorporate the film as an insulating material.

[0203] <Laminate> The laminate of the embodiment comprises a metal layer and a film according to the embodiment laminated on the metal layer. Figure 3 is a schematic diagram showing the configuration of a laminate 21 according to one embodiment of the present invention. The laminate 21 comprises a metal layer 13 and a film 11 laminated on the metal layer 13. The films incorporated into the laminate are exemplified above, and their explanation will be omitted. Regarding the metal layer included in the laminate, examples of the support in the above-mentioned <<Method for Producing Liquid Crystal Polyester Film>> and <<Method for Producing Laminate>> can be mentioned, and a metal foil is preferred. As the metal constituting the metal layer, copper is preferred from the viewpoints of conductivity and cost, and as the metal foil, a copper foil is preferred.

[0204] Although the thickness of the laminate of the embodiment is not particularly limited, it is preferably 5 to 130 μm, more preferably 10 to 70 μm, and even more preferably 15 to 60 μm.

[0205] Although the method for producing the laminate of the embodiment is not particularly limited, the laminate of the embodiment can be produced by the above-mentioned <<Method for Producing Laminate>>.

[0206] The laminate of the embodiment can be suitably used for film applications for electronic components such as printed wiring boards.

Examples

[0207] Next, examples will be shown to explain the present invention in more detail, but the present invention is not limited to the following examples.

[0208] 〔Measurement of Flow Initiation Temperature of Liquid Crystal Polyester〕 Using a flow tester (''CFT-500 type'' manufactured by Shimadzu Corporation), about 2 g of liquid crystal 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, and under a load of 9.8 MPa (100 kg / cm 2 ), while raising the temperature at a rate of 4 °C / min, the liquid crystal polyester was melted, extruded from the nozzle, and the temperature (FT) at which a viscosity of 4800 Pa·s (4800 P) was exhibited was measured.

[0209] 〔Measurement of Particle Diameter of Liquid Crystal Polyester Powder〕 0.01 g of liquid crystal polyester powder was weighed and dispersed in approximately 10 g of pure water. The prepared dispersion of liquid crystal polyester powder was dispersed by ultrasound for 5 minutes. Using a laser diffraction / scattering particle size distribution analyzer ("LA-950V2" from HORIBA Corporation), the volume-based cumulative particle size distribution of the liquid crystal polyester powder was measured, with the refractive index of pure water set to 1.333. The particle size (μm) at which the cumulative volume percentage from the smallest particles became 90% was defined as D 90 It was calculated as follows. Furthermore, from the obtained cumulative particle size distribution, the percentage (by volume) of particles with a particle size of 30 μm or larger and the percentage (by volume) of particles with a particle size of 20 μm or larger were calculated relative to the total volume of liquid crystal polyester powder used for measurement.

[0210] [Measurement of tensile strength of liquid crystal polyester film] The copper foil of a single-sided copper-clad liquid crystal polyester film was etched off using a ferric chloride solution to obtain a single-layer liquid crystal polyester film. The obtained liquid crystal polyester film was cut into dumbbell-shaped test pieces (parallel section width 5 mm, length 20 mm) according to JIS K6251, and a tensile test was performed using a tensile testing machine (Shimadzu Corporation, Autograph AG-IS) in accordance with JIS K7161 at a tensile speed of 5 mm / min. The tensile strength (MPa) and tensile strain (%) of the liquid crystal polyester film were determined at 23°C and 50% RH humidity.

[0211] [Manufacturing of liquid crystal polyester (A)] In a reactor equipped with a stirrer, torque meter, nitrogen gas inlet tube, thermometer, and reflux condenser, 940.9 g (5.0 mol) of 6-hydroxy-2-naphthoic acid, 377.9 g (2.5 mol) of acetaminophen, 415.3 g (2.5 mol) of isophthalic acid, and 867.8 g (8.4 mol) of acetic anhydride were added. After replacing the gas in the reactor with nitrogen gas, the temperature was raised from room temperature to 140°C over 60 minutes while stirring under a nitrogen gas flow, and then refluxed at 140°C for 3 hours. Next, while distilling off the by-product acetic acid and unreacted acetic anhydride, the temperature was raised from 150°C to 300°C over 5 hours, and held at 300°C for 30 minutes. After that, the contents were removed from the reactor and cooled to room temperature. The obtained solid was pulverized to obtain powdered liquid crystal polyester (A1). The flow initiation temperature of this liquid crystal polyester (A1) was 193.3°C.

[0212] Liquid crystal polyester (A1) was heated in a nitrogen atmosphere from room temperature to 160°C over 2 hours and 20 minutes, then heated from 160°C to 180°C over 3 hours and 20 minutes, and held at 180°C for 5 hours to undergo solid-phase polymerization. After cooling, it was pulverized in a pulverizer to obtain powdered liquid crystal polyester (A2). The flow initiation temperature of this liquid crystal polyester (A2) was 220°C.

[0213] Liquid crystal polyester (A2) was heated in a nitrogen atmosphere from room temperature to 180°C over 1 hour and 25 minutes, then heated from 180°C to 255°C over 6 hours and 40 minutes, and held at 255°C for 5 hours to undergo solid-phase polymerization. After cooling, powdered liquid crystal polyester (A) was obtained. The flow initiation temperature of liquid crystal polyester (A) was 302°C.

[0214] [Preparation of liquid crystal polyester solution] Eight parts by mass of liquid crystal polyester (A) were added to 92 parts by mass of N-methylpyrrolidone (boiling point (1 atm) 204°C), and the mixture was stirred at 140°C for 4 hours under a nitrogen atmosphere to prepare a liquid crystal polyester solution. Liquid crystal polyester (A) was soluble in N-methylpyrrolidone. The viscosity of this liquid crystal polyester solution at 23°C was 955 mPa·s.

[0215] [Manufacturing of liquid crystal polyester (B1)] In a reactor equipped with a stirrer, torque meter, nitrogen gas inlet tube, thermometer, and reflux condenser, 1034.99 g (5.5 mol) of 2-hydroxy-6-naphthoic acid, 378.33 g (1.75 mol) of 2,6-naphthalenedicarboxylic acid, 83.07 g (0.5 mol) of terephthalic acid, 272.52 g (2.475 mol, 0.225 mol excess of the total molar amount of 2,6-naphthalenedicarboxylic acid and terephthalic acid), 1226.87 g (12 mol) of acetic anhydride, and 0.17 g of 1-methylimidazole as a catalyst were added. After replacing the gas in the reactor with nitrogen gas, the temperature was raised from room temperature to 145°C over 15 minutes while stirring under a nitrogen gas stream, and then refluxed at 145°C for 1 hour.

[0216] Next, while distilling off the by-product acetic acid and unreacted acetic anhydride, the temperature was raised from 145°C to 310°C over 3 hours and 30 minutes. After holding at 310°C for 10 minutes, the solid liquid crystal polyester (B1) was extracted and cooled to room temperature. The flow initiation temperature of this polyester (B1) was 251.6°C.

[0217] [Powder of Example 1: Production of liquid crystal polyester powder (B2)] Using a jet mill (KJ-200 from Kurimoto Iron Works), the liquid crystal polyester (B1) was pulverized with a classification rotor rotation speed of 10,000 rpm, a pulverizing nozzle pressure of 0.71 MPa, and a processing speed of 1.1 kg / hour to obtain the liquid crystal polyester powder (B2) of Example 1. D of this liquid crystal polyester powder (B2) 90 The percentage of particles with a diameter of 8 μm or larger, 30 μm or larger, was 0 volume%, and the percentage of particles with a diameter of 20 μm or larger was also 0 volume%.

[0218] [Powder of Example 2: Production of liquid crystal polyester powder (B3)] Using a jet mill (KJ-200 from Kurimoto Iron Works), the liquid crystal polyester (B1) was pulverized with a classification rotor rotation speed of 10,000 rpm, a grinding nozzle pressure of 0.73 MPa, and a processing speed of 1.8 kg / hour to obtain the liquid crystal polyester powder (B3) of Example 2. 90 The percentage of particles with a diameter of 13 μm or larger, 30 μm or larger, was 0 volume%, and the percentage of particles with a diameter of 20 μm or larger was 1.7 volume%.

[0219] [Comparative Example 1 Powder: Manufacturing of liquid crystal polyester powder (B4)] Using a jet mill (KJ-200 from Kurimoto Iron Works), the liquid crystal polyester (B1) was pulverized with a classification rotor rotation speed of 10,000 rpm, a grinding nozzle pressure of 0.74 MPa, and a processing speed of 2.7 kg / hour to obtain the liquid crystal polyester powder (B4) of Comparative Example 1. 90 The percentage of particles with a diameter of 24 μm or larger, 30 μm or larger, was 4.9 volume%, and the percentage of particles with a diameter of 20 μm or larger was 15.6 volume%.

[0220] [Preparation of dispersion] Each of the liquid crystal polyester solutions obtained above contained 85.2 parts by mass of NMP, 7.4 parts by mass of liquid crystal polyester (A), and 7.4 parts by mass of each of the liquid crystal polyester powders (B2) to (B4) of each example and comparative example. A liquid crystal polyester solution containing liquid crystal polyester (A) and one of the liquid crystal polyester powders (B2) to (B4) were added to each solution, and dispersions (liquid crystal polyester compositions) containing each powder from Examples 1 and 2 and Comparative Example 1 were prepared using a stirring and defoaming apparatus (Keyence Corporation HM-500).

[0221] [Manufacturing of liquid crystal polyester film] Each dispersion liquid prepared above was cast onto the roughened surface of a copper foil (3EC-VLP 18 μm manufactured by Mitsui Mining & Smelting Co., Ltd.) so that the thickness of the cast film became 280 μm, using a film applicator with a micrometer ("SA204" manufactured by SHEEN) and an automatic coating device ("Type I" manufactured by Tester Sangyo Co., Ltd.). Thereafter, the solvent was partially removed from the cast film by drying at 40 °C and normal pressure (1 atm) for 4 hours.

[0222] The film with the dried copper foil prepared above was further heated from room temperature to 310 °C in 4 hours in a hot air oven under a nitrogen atmosphere and heat-treated by holding at that temperature for 2 hours. As a result, a heat-treated film with a copper foil was obtained. The copper foil of this film with a copper foil was removed by etching using a ferric chloride solution to obtain a single-layer liquid crystal polyester film. The thickness of the liquid crystal polyester film (film of Example 1) using the powder of Example 1 was 23 μm, the thickness of the liquid crystal polyester film (film of Example 2) using the powder of Example 2 was 24 μm, and the thickness of the liquid crystal polyester film (film of Comparative Example 1) using the powder of Comparative Example 1 was 30 μm. Tensile strength and tensile strength strain were measured for these single-layer liquid crystal polyester films. The results are shown in Table 1.

[0223]

Table 1

[0224] As shown in the above results, D of the liquid crystal polyester powder 90 was 20 μm or less, and the films of Example 1 and Example 2 to which the present invention was applied showed excellent film strength (tensile strength and tensile strength strain) compared to the film of Comparative Example 1.

[0225] Also, the smaller the value of D of the liquid crystal polyester powder 90 , the more improved the film strength of the obtained liquid crystal polyester film was.

[0226] Furthermore, the film strength of the resulting liquid crystal polyester film was improved by reducing the proportion of particles with a particle size of 30 μm or larger in the liquid crystal polyester powder.

[0227] Similarly, when examining the proportion of particles with a particle size of 20 μm or larger in the liquid crystal polyester powder, the lower the proportion, the higher the film strength of the resulting liquid crystal polyester film.

[0228] Each configuration and combination thereof in each embodiment is merely an example, and additions, omissions, substitutions, and other modifications are possible without departing from the spirit of the present invention. Furthermore, the present invention is not limited by each embodiment, but is limited only by the scope of the claims. [Explanation of Symbols]

[0229] 1...Liquid crystal polyester powder, 3...Medium, 4...Resin, 30...Liquid crystal polyester composition, 10,11...Liquid crystal polyester film, 12...Support, 13...Metal layer, 20,21...Laminate, 22...Laminate precursor, 40...Liquid crystal polyester film precursor

Claims

1. A liquid crystal polyester powder containing liquid crystal polyester, In a volume-based cumulative particle size distribution curve obtained by laser diffraction / scattering particle size distribution measurement, the particle size at which the cumulative volume proportion from the smallest particles accounts for 90% is defined as D. ９０ When that happens, The aforementioned D ９０ It is 20 μm or less, The liquid crystal polyester has a flow initiation temperature of 220°C or higher and 255°C or lower. The liquid crystal polyester has structural units including a naphthalene structure, The content of structural units including the naphthalene structure is 40 mol% or more relative to the total amount of all structural units in the liquid crystal polyester, which is 100 mol%. The liquid crystal polyester has a structural unit represented by the following formula (1), a structural unit represented by the following formula (2), and a structural unit represented by the following formula (3), Liquid crystal polyester powder having a ratio expressed as [content of structural unit (2)] / [content of structural unit (3)] (moles / moles) of 0.9 or more and 1.1 or less. (1) -O-Ar1-CO- (2) -CO-Ar2-CO- (3) -X-Ar3-Y- [In formulas (1) to (3), Ar1 represents a phenylene group, a naphthylene group, or a biphenylylene group.] Ar2 and Ar3 independently represent a phenylene group, a naphthylene group, a biphenylylene group, or a group represented by the following formula (4). X and Y independently represent an oxygen atom or an imino group (-NH-). One or more hydrogen atoms in the group represented by Ar1, Ar2, or Ar3 may be independently substituted with a halogen atom, a C1-C10 alkyl group, or a C6-C20 aryl group. (4)-Ar4-Z-Ar5- [In formula (4), Ar4 and Ar5 independently represent a phenylene group or a naphthylene group. 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 independently substituted with a halogen atom, a C1-C10 alkyl group, or a C6-C20 aryl group.

2. The liquid crystal polyester powder according to claim 1, wherein the D 90 is 10 μm or less.

3. The liquid crystal polyester powder according to claim 1 or 2, wherein the D90 is 8 μm or less.

4. The liquid crystal polyester powder according to any one of claims 1 to 3, wherein the proportion of particles with a particle diameter of 30 μm or more, as measured by laser diffraction / scattering particle size distribution measurement, is 3% by volume or less with respect to the total volume of the liquid crystal polyester powder.

5. The liquid crystal polyester powder according to any one of claims 1 to 4, wherein the proportion of particles with a particle diameter of 20 μm or more, as measured by laser diffraction / scattering particle size distribution measurement, is 7 volume% or less of the total volume of the liquid crystal polyester powder.

6. A liquid crystal polyester composition comprising a medium and the liquid crystal polyester powder described in any one of claims 1 to 5.

7. The liquid crystal polyester composition according to claim 6, wherein the liquid crystal polyester powder is insoluble in the medium.

8. Furthermore, the liquid crystal polyester composition according to claim 6 or 7, further comprising a resin soluble in the medium.

9. The liquid crystal polyester composition according to claim 8, wherein the resin soluble in the medium is a liquid crystal polyester soluble in the medium.

10. A method for producing a liquid crystal polyester composition according to any one of claims 6 to 9, comprising mixing a medium with a liquid crystal polyester powder according to any one of claims 1 to 5.

11. A method for producing a liquid crystal polyester film, comprising applying a liquid crystal polyester composition according to any one of claims 6 to 9 onto a support, and heat-treating it to obtain a liquid crystal polyester film containing liquid crystal polyester.

12. A method for manufacturing a laminate, comprising applying a liquid crystal polyester composition according to any one of claims 6 to 9 onto a support, heat-treating it to form a liquid crystal polyester film containing liquid crystal polyester, thereby obtaining a laminate comprising the support and the liquid crystal polyester film.

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