TWI837303B - Liquid crystal polyester powder, liquid crystal polyester composition, film manufacturing method, and laminate manufacturing method - Google Patents

Abstract

A liquid crystal polyester powder comprises a liquid crystal polyester having a number average molecular weight of less than 10,000 and an average particle size of 0.5 to 20 μm.

Description

Liquid crystal polyester powder, liquid crystal polyester composition, film production method and laminate production method

The present invention relates to a method for producing a liquid crystal polyester powder, a liquid crystal polyester composition, a film, and a method for producing a laminate. This application claims priority based on application No. 2019-025664 filed in Japan on February 15, 2019 and application No. 2019-141072 filed in Japan on July 31, 2019, the contents of which are cited in this article.

Insulating materials are used in printed circuit boards on which electronic components are mounted. In recent years, due to the development of communication systems, it is expected that the physical properties of insulating materials such as dielectric properties will be further improved. For example, in Patent Document 1, an insulating resin composition including a silane-containing epoxy resin, a hardener, and an inorganic filler such as silicon oxide is described for the purpose of reducing dielectric loss. [Prior Technical Document] [Patent Document]

[Patent Document 1] Japanese Patent Application Publication No. 2017-66360

[Problems to be solved by the invention]

However, if an inorganic filler is added to the resin composition as described in Patent Document 1, there is a problem of reduced adhesion strength with the metal foil and reduced mechanical strength of the insulating substrate. And if the application to the next generation mobile communication system is considered, there is a high possibility that the dielectric properties of the previous substrate material will become insufficient at high frequencies.

Liquid crystal polyester film has attracted much attention as an electronic substrate material due to its excellent high-frequency characteristics and low water absorption.

The purpose of the present invention is to provide a liquid crystal polyester powder and a liquid crystal polyester composition that can produce a liquid crystal polyester film having a quality suitable for use as a film for electronic parts. In addition, the purpose of the present invention is to provide a method for producing a liquid crystal polyester film and a method for producing a laminate that can produce a liquid crystal polyester film having a quality suitable for use as a film for electronic parts. [Means for Solving the Problem]

As a result of the active research to solve the above-mentioned problems, the inventors of the present invention have found that a high-quality liquid crystal polyester film can be produced by using a liquid crystal polyester powder containing a liquid crystal polyester having a specific molecular weight and a specific average particle size, thereby completing the present invention. That is, one aspect of the present invention is the following liquid crystal polyester powder, liquid crystal polyester composition, film production method and laminate production method.

<1> A liquid crystal polyester powder, comprising a liquid crystal polyester having a number average molecular weight of 10,000 or less and an average particle size of 0.5 to 20 μm. <2> The liquid crystal polyester powder as described in <1> above, wherein the relative permittivity at a frequency of 1 GHz is 3 or less, and the dielectric tangent at a frequency of 1 GHz is 0.005 or less. <3> The liquid crystal polyester powder as described in <1> or <2> above, wherein the liquid crystal polyester has structural units comprising a naphthalene structure. <4> The liquid crystal polyester powder as described in <3> above, wherein the content of the structural units comprising a naphthalene structure is 40 mol% or more relative to 100 mol% of the total amount of all structural units in the liquid crystal polyester. <5> The liquid crystal polyester powder as described in <3> or <4> above, wherein the liquid crystal polyester has 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), (Ar ¹ represents 2,6-naphthalenediyl, 1,4-phenylene or 4,4'-biphenylene, Ar ² and Ar ³ independently represent 2,6-naphthalenediyl, 2,7-naphthalenediyl, 1,4-phenylene, 1,3-phenylene or 4,4'-biphenylene, and Ar ¹ , Ar ² or Ar ³ represents that the hydrogen atom of the aforementioned group may be independently substituted by a halogen atom, an alkyl group having 1 to 10 carbon atoms or an aryl group having 6 to 20 carbon atoms.) <6> A liquid crystal polyester composition comprising a medium and a liquid crystal polyester powder as described in any one of <1> to <5> above. <7> A method for producing a liquid crystal polyester film, comprising coating the liquid crystal polyester composition as described in <6> above on a support and performing a heat treatment to obtain a liquid crystal polyester film comprising the liquid crystal polyester. <8> A method for manufacturing a laminate, comprising coating the liquid crystal polyester composition of <6> on a support, performing heat treatment to form a liquid crystal polyester film containing liquid crystal polyester, and obtaining a laminate having the support and the liquid crystal polyester film.

That is, the present invention includes the following aspects. <1> A liquid crystal polyester powder, which contains a liquid crystal polyester with a number average molecular weight of less than 10,000 and an average particle size of 0.5 to 20 μm. <2> The liquid crystal polyester powder as described in <1> above, wherein the relative permittivity at a frequency of 1 GHz is less than 3, and the dielectric tangent at a frequency of 1 GHz is less than 0.005. <3> The liquid crystal polyester powder as described in <1> or <2> above, wherein the liquid crystal polyester has a structural unit containing a naphthalene structure. <4> The liquid crystal polyester powder as described in <3> above, wherein the content of the structural unit containing a naphthalene structure is greater than 40 mol % relative to the total amount of all structural units in the liquid crystal polyester of 100 mol %. <5> The liquid crystal polyester powder as described in <3> or <4> above, wherein 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), (Ar ¹ represents 2,6-naphthalenediyl, 1,4-phenylene or 4,4'-biphenylene, Ar 2 and Ar ³ represent 2,6-naphthalenediyl, 2,7-naphthalenediyl, 1,4-phenylene, 1,3-phenylene or 4,4'-biphenylene, and Ar ¹ , Ar ² or ^{Ar 3 represent} that the hydrogen atom of the aforementioned group may be independently substituted by a halogen atom, an alkyl group having 1 to 10 carbon atoms or an aryl group having 6 to 20 carbon atoms.) <6> The liquid crystal polyester powder as described in any one of <1> to <5> above, which is insoluble in an aprotic solvent. <7> A liquid crystal polyester composition comprising a medium and the liquid crystal polyester powder as described in any one of <1> to <6> above. <8> The liquid crystal polyester composition as described in <7> above, wherein the medium is an aprotic solvent. <9> A method for producing a liquid crystal polyester film, comprising coating the liquid crystal polyester composition of <7> or <8> on a support, and performing heat treatment to obtain a liquid crystal polyester film containing a liquid crystal polyester. <10> A method for producing a laminate, comprising coating the liquid crystal polyester composition of <7> or <8> on a support, and performing heat treatment to form a liquid crystal polyester film containing a liquid crystal polyester, thereby obtaining a laminate having the support and the liquid crystal polyester film. [Effect of the invention]

According to the present invention, a liquid crystal polyester powder and a liquid crystal polyester composition can be provided for producing a liquid crystal polyester film having a quality suitable for use as a film for electronic components. In addition, according to the present invention, a method for producing a liquid crystal polyester film and a method for producing a laminate can be provided for producing a liquid crystal polyester film having a quality suitable for use as a film for electronic components.

The following describes the implementation forms of the liquid crystal polyester powder, liquid crystal polyester composition, film production method and laminate production method of the present invention.

＜＜Liquid crystal polyester powder＞＞ The liquid crystal polyester powder of the embodiment comprises a liquid crystal polyester having a number average molecular weight of less than 10,000 and an average particle size of 0.5 to 20 μm. The liquid crystal polyester powder of the embodiment can be preferably used as a raw material for the manufacturing method of the liquid crystal polyester film or laminate of the embodiment. According to the liquid crystal polyester powder that meets the above requirements, a liquid crystal polyester film having a quality suitable for use as a film for electronic parts can be manufactured. As a quality standard, the isotropy, thickness and appearance (whether there are holes or through holes) of the film are given as examples. The details of the liquid crystal polyester film will be described later.

The average particle size of the liquid crystal polyester powder is less than 20μm, preferably less than 18μm, more preferably less than 15μm, and even more preferably less than 10μm. When the average particle size of the liquid crystal polyester powder exceeds 20μm, it is difficult to obtain a liquid crystal polyester film with good appearance. For example, as shown in the embodiment described below, when the average particle size of the liquid crystal polyester powder exceeds 20μm, through holes may occur on the liquid crystal polyester film produced. Through hole formation is easy to occur in the range of 50μm or less, which is a more suitable thickness range for thin films for electronic parts. That is, by making the average particle size of the liquid crystal polyester less than 20μm, a film with both appropriate thickness and appearance as a film for electronic parts can be easily produced. Moreover, from the viewpoint of easy handling of the powder, the average particle size of the liquid crystal polyester powder is preferably 0.5 μm or more, more preferably 3 μm or more, and even more preferably 5 μm or more. The upper limit and lower limit of the average particle size of the above-mentioned liquid crystal polyester powder can be freely combined. As an example of the numerical range of the average particle size of the above-mentioned liquid crystal polyester powder, it can be 0.5 μm or more and 20 μm or less, 3 μm or more and 18 μm or less, 5 μm or more and 15 μm or less, or 5 μm or more and 10 μm or less.

In this specification, the "average particle size" refers to the particle size value at the point where the cumulative volume is 50% when the total is set to 100% in the volume-based cumulative particle size distribution curve measured by the laser diffraction scattering method (50% cumulative volume particle size D ₅₀ ).

As a method for controlling the particle size within the above range, when a jet mill is used, for example, the particle size can be controlled by changing the rotation speed of the classifying drum, the pulverizing nozzle pressure, the processing speed, etc.

In addition, in the manufacturing method of the liquid crystal polyester film or laminate of the embodiment described below, since the liquid crystal polyester powder does not need to be dissolved in a solvent, a liquid crystal polyester powder with excellent dielectric properties can be used as a raw material. Liquid crystal polyester films with excellent dielectric properties can be manufactured from liquid crystal polyester powders with excellent dielectric properties. In this specification, the so-called "dielectric properties" refers to properties related to relative permittivity and dielectric tangent.

The relative capacitance of the liquid crystal polyester powder of the embodiment at a frequency of 1 GHz is preferably 3 or less, more preferably 2.9 or less, more preferably 2.8 or less, more preferably less than 2.8, still more preferably 2.78 or less, and particularly preferably 2.76 or less. In addition, the relative capacitance of the liquid crystal polyester powder may be 2.5 or more, 2.6 or more, or 2.7 or more. The upper limit and lower limit of the relative capacitance of the liquid crystal polyester powder may be freely combined. As an example of the numerical range of the relative capacitance of the liquid crystal polyester powder, it may be 2.5 or more and 3 or less, 2.6 or more and 2.78 or more, or 2.7 or more and 2.76 or less.

The dielectric tangent of the liquid crystal polyester powder in the embodiment at a frequency of 1 GHz is preferably 0.005 or less, 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. Moreover, the dielectric tangent of the liquid crystal polyester powder may be 0.0003 or more, 0.0005 or more, or 0.001 or more. The upper limit and lower limit of the dielectric tangent of the liquid crystal polyester powder may be freely combined. As an example of the numerical range of the dielectric tangent of the liquid crystal polyester powder, 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 0.002 or less. The relative capacitance and dielectric tangent of the liquid crystal polyester powder at a frequency of 1 GHz can be measured under the following conditions by the capacitance method using an impedance analyzer. The liquid crystal polyester microparticle powder is melted at a temperature 5°C higher than the melting point measured using a flow tester, and then cooled and solidified to prepare a tablet with a diameter of 1 cm and a thickness of 0.5 cm. The relative capacitance and dielectric tangent of the obtained tablet at 1 GHz are measured under the following conditions. ・Measurement method: capacitance method ・Electrode type: 16453A ・Measurement environment: 23°C, 50%RH ・Applied voltage: 1V

In addition, the relative permittivity and dielectric tangent of the liquid crystal polyester powder in the embodiment are sometimes different from those of the liquid crystal polyester film produced using the powder as a raw material. This is believed to be due to the difference in molecular weight of the liquid crystal polyester contained therein.

The liquid crystal polyester powder is preferably insoluble in the medium contained in the liquid crystal polyester composition described below, and more preferably insoluble in a protic solvent. Here, whether the liquid crystal polyester powder is insoluble in the medium can be confirmed by performing the following test. The following test method is explained for the case where the medium is a non-protic solvent.

・Test method The liquid crystal polyester powder (5 parts by weight) is placed in an aprotic solvent (medium) (95 parts by weight) at 180°C and stirred at 200 rpm using an anchor blade for 6 hours, then cooled to room temperature. Next, the mixture is filtered using a 5μm mesh membrane filter and a pressure filter, and the residue on the membrane filter is confirmed. At this time, if no solids are confirmed, it is judged to be soluble in the aprotic solvent (medium). If solids with a short diameter of 5μm or more are confirmed, it is judged to be insoluble in the aprotic solvent (medium). Solids with a short diameter of 5μm or more can be confirmed by observation under a microscope.

The content ratio of the liquid crystal polyester relative to 100 mass % of the liquid crystal polyester powder of the embodiment can be 50-100 mass % or 80-95 mass %.

The number average molecular weight of the liquid crystal polyester in the liquid crystal polyester powder of the embodiment is 10,000 or less, preferably 3,000 to 10,000, 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 exceeds 10,000, the liquid crystal polyester composition becomes a gel, and it is difficult to process the film with excellent isotropy. The smaller the number average molecular weight of the liquid crystal polyester, the better the tendency of improving the thermal conductivity in the thickness direction of the film after heat treatment. If the number average molecular weight of the liquid crystal polyester is above the above lower limit, the heat resistance or strength and rigidity of the film after heat treatment are good.

In this specification, the so-called "number average molecular weight" is an absolute value measured using a gel penetration chromatography-multi-angle light scattering photometer.

The following describes the details of the liquid crystal polyester contained in the liquid crystal polyester powder of the embodiment.

(Liquid crystal polyester) Liquid crystal polyester is a liquid crystal polyester that exhibits liquid crystal properties in a molten state, preferably one that melts at a temperature below 450°C. 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. In addition, the term "derived from" in this specification means that the chemical structure of the functional group that contributes to the polymerization is changed in order to polymerize the raw material monomers, and other structures are not changed.

Typical examples of liquid crystal polyesters are as follows. 1) Polymerization (polycondensation) of (i) aromatic hydroxycarboxylic acid, (ii) aromatic dicarboxylic acid and (iii) at least one compound selected from the group consisting of aromatic diols, aromatic hydroxylamines and aromatic diamines. 2) Polymerization of a plurality of aromatic hydroxycarboxylic acids. 3) Polymerization of (i) aromatic dicarboxylic acid and (iii) at least one compound selected from the group consisting of aromatic diols, aromatic hydroxylamines and aromatic diamines. 4) Polymerization of (i) polyester such as polyethylene terephthalate and (ii) aromatic hydroxycarboxylic acid. Here, aromatic hydroxycarboxylic acid, aromatic dicarboxylic acid, aromatic diol, aromatic hydroxylamine and aromatic diamine may be replaced with their polymerizable derivatives, respectively, in part or in whole.

Examples of polymerizable derivatives of compounds having a carboxyl group such as aromatic hydroxycarboxylic acids and aromatic dicarboxylic acids include those in which the carboxyl group is converted to an alkoxycarbonyl group or an aryloxycarbonyl group (esters), those in which the carboxyl group is converted to a halogenated methyl group (acid halides), and those in which the carboxyl group is converted to an acyloxycarbonyl group (acid anhydrides). Examples of polymerizable derivatives of compounds having a hydroxyl group such as aromatic hydroxycarboxylic acids, aromatic diols, and aromatic hydroxylamines include those in which the hydroxyl group is acylated to be converted to an acyloxy group (acylates). Examples of polymerizable derivatives of compounds having an amine group such as aromatic hydroxyamines and aromatic diamines include those in which the amine group is acylated to be converted to an acylamine group (acylates).

The liquid crystal polyester preferably has a structural unit containing a divalent aromatic hydrocarbon group. Examples of the liquid crystal polyester having a structural unit containing a divalent aromatic hydrocarbon group include 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), or a structural unit represented by the following formula (2) and a structural unit represented by the following formula (3). (Ar ¹ , Ar ² and Ar ³ each independently represent a divalent aromatic hydrocarbon group, and the hydrogen atom of the aforementioned group represented by Ar ¹ , Ar ² or Ar ³ may be independently substituted by a halogen atom, an alkyl group having 1 to 10 carbon atoms or an aryl group having 6 to 20 carbon atoms).

Examples of the divalent aromatic hydrocarbon group in Ar ¹ , Ar ² and Ar ³ include phenylene, naphthylene, biphenylene and the like.

Here, the aforementioned halogen atom in Ar ¹ , Ar ² and Ar ³ is exemplified by fluorine atom, chlorine atom, bromine atom and iodine atom. Examples of the aforementioned alkyl group include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, t-butyl, n-hexyl, 2-ethylhexyl, n-octyl and n-decyl, and the carbon number of the group is usually 1 to 10. Examples of the aforementioned aryl group include phenyl, o-tolyl, m-tolyl, p-tolyl, 1-naphthyl and 2-naphthyl, and the carbon number of the group is usually 6 to 20. When the aforementioned hydrogen atom is substituted by these groups, the number of the aforementioned hydrogen atom in each of the aforementioned groups represented by Ar ¹ , Ar ² and Ar ³ is usually 2 or less, preferably 1 or less, respectively.

The liquid crystal polyester preferably has a structural unit containing a naphthalene structure. Examples of the liquid crystal polyester having a structural unit containing a divalent naphthalene structure include 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), or a structural unit represented by the following formula (2) and a structural unit represented by the following formula (3). [Ar ¹ , Ar ² and Ar ³ each independently represent a divalent aromatic hydrocarbon group (but at least one of the plural Ar ¹ , Ar ² and Ar ³ is a naphthyl group), and the hydrogen atom of Ar ¹ , Ar ² or Ar ³ each independently represents a halogen atom, an alkyl group having 1 to 10 carbon atoms or an aryl group having 6 to 20 carbon atoms].

Ar ¹ , Ar ² and Ar ³ may each independently represent a naphthylene group or a phenylene group (but at least one of the plural Ar ¹ , Ar ² and Ar ³ is a naphthylene group).

The liquid crystal polyester preferably has a structural unit represented by the above formula (1), a structural unit represented by the above formula (2), and a structural unit represented by the above formula (3), and when at least one of the plurality of Ar ¹ , Ar ² , and Ar ³ is a naphthylene group, at least one of the plurality of Ar ¹ and/or Ar ² is a naphthylene group. The liquid crystal polyester preferably has a structural unit represented by the above formula (2) and a structural unit represented by the above formula (3), and when at least one of the plurality of Ar ² and Ar ³ is a naphthylene group, at least one of the plurality of Ar ² is a naphthylene group.

The naphthylene group in Ar ¹ , Ar ² and Ar ³ is preferably 2,6-naphthalenediyl or 2,7-naphthalenediyl, more preferably 2,6-naphthalenediyl.

The content of the structural unit containing a naphthalene structure in the liquid crystal polyester is preferably 40 mol% or more, more preferably 50 mol% or more, and even more preferably 60 mol% or more, relative to the total amount of all structural units of the liquid crystal polyester of 100 mol% (the equivalent amount (molar) of the mass of each structural unit constituting the liquid crystal polyester is obtained by dividing the mass of each structural unit by the formula weight of each structural unit, and the total value is taken). By making the content of the structural unit containing a naphthalene structure above the above lower limit, the relative capacitance of the liquid crystal polyester can be further reduced. The content of the structural unit containing a naphthalene structure in the liquid crystal polyester is preferably 90 mol% or less, and more preferably 80 mol% or less, relative to the total amount of all structural units of the liquid crystal polyester of 100 mol%. By making the content of the structural unit containing the naphthalene structure below the above upper limit, the reaction stability when producing the liquid crystal polyester can be ensured. As an example of the numerical range of the content value of the structural unit containing the naphthalene structure, it can be 40 mol% to 90 mol%, 50 mol% to 80 mol%, or 60 mol% to 80 mol%.

The liquid crystal polyester may be a polyester having a structural unit represented by the above formula (2) and a structural unit represented by the above formula (3) among the structural units represented by the above formulas (1) to (3), or a polyester having all types of structural units represented by the above formulas (1) to (3). The liquid crystal polyester may be a polyester having a structural unit represented by the above formula (2) and a structural unit represented by the above formula (3) among the structural units represented by the above formulas (1) to (3), or a polyester having all types of structural units represented by the above formulas (1) to (3).

Examples of the liquid crystal polyester having the structural units represented by the above formulae (1) to (3) include a liquid crystal polyester having 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). (Ar ¹ , Ar ² and Ar ³ each independently represent a naphthalene diyl group, a phenylene group or a biphenylene group, and the hydrogen atom of the aforementioned groups represented by Ar ¹ , Ar ² or Ar ³ may be independently substituted by a halogen atom, an alkyl group having 1 to 10 carbon atoms or an aryl group having 6 to 20 carbon atoms).

The above-mentioned liquid crystal polyester includes the following liquid crystal polyester: A liquid crystal polyester having 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). (Ar ¹ represents 2,6-naphthalenediyl, 1,4-phenylene or 4,4'-biphenylene, Ar ² and Ar ³ represent 2,6-naphthalenediyl, 2,7-naphthalenediyl, 1,4-phenylene, 1,3-phenylene or 4,4'-biphenylene, and the hydrogen atom of Ar ¹ , Ar ² or Ar ³ represents the above groups may be substituted by a halogen atom, an alkyl group having 1 to 10 carbon atoms or an aryl group having 6 to 20 carbon atoms, respectively and independently).

Examples of the liquid crystal polyester having the structural units represented by the above formulae (1) to (3) include a liquid crystal polyester having 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). (Ar ¹ represents naphthalene diyl, Ar ² represents naphthalene diyl or phenylene, Ar ³ represents phenylene, Ar ¹ , Ar ² or Ar ³ represents that the hydrogen atom of the aforementioned groups may be independently substituted by a halogen atom, an alkyl group having 1 to 10 carbon atoms or an aryl group having 6 to 20 carbon atoms)

When the liquid crystal polyester has all types of structural units represented by the above formulae (1) to (3), the preferred content ratio of each structural unit in the liquid crystal polyester can be exemplified as follows.

The content ratio of the structural unit (1) in the liquid crystal polyester is preferably 30 mol% to 80 mol% relative to the total amount of all structural units in the liquid crystal polyester (100 mol%), more preferably 40 mol% to 70 mol% and even more preferably 45 mol% to 65 mol%. In addition, the content ratio of the structural unit (2) in the liquid crystal polyester is preferably 10 mol% to 35 mol% relative to the total amount of all structural units in the liquid crystal polyester (100 mol%), more preferably 15 mol% to 30 mol% and even more preferably 17.5 mol% to 27.5 mol%. Furthermore, the content ratio of the structural unit (3) in the liquid crystal polyester is preferably 10 mol% to 35 mol% relative to the total amount of all structural units in the liquid crystal polyester (100 mol%), more preferably 15 mol% to 30 mol%, and even more preferably 17.5 mol% to 27.5 mol%. Furthermore, the content of the structural unit (2) in the liquid crystal polyester is preferably equal to the content of the structural unit (3), but when the contents are different, the difference between the content of the structural unit (2) and the content of the structural unit (3) is expected to be 5 mol% or less.

An example of a liquid crystal polyester having high heat resistance or melt tension is one in which the content ratio of Ar ¹ in the structural unit (1) being a 2,6-naphthalenediyl group (e.g., a structural unit derived from 2-hydroxy-6-naphthoic acid) is preferably 40 mol % to 74.8 mol %, more preferably 40 mol % to 64.5 mol %, and even more preferably 50 mol % to 58 mol %, relative to the total amount of all structural units in the liquid crystal polyester.

In the liquid crystal polyester, the content ratio of Ar ² of the structural unit (2) being a 2,6-naphthalene diyl group (for example, a structural unit derived from 2,6-naphthalene dicarboxylic acid) is preferably from 10.0 mol % to 35 mol %, more preferably from 12.5 mol % to 30 mol %, and even more preferably from 15 mol % to 25 mol %, relative to the total amount of all structural units in the liquid crystal polyester.

In the liquid crystal polyester, the content ratio of Ar ² of the structural unit (2) being 1,4-phenylene (for example, a structural unit derived from terephthalic acid) is preferably 0.2 mol % to 15 mol %, more preferably 0.5 mol % to 12 mol %, and even more preferably 2 mol % to 10 mol %, relative to the total amount of all structural units in the liquid crystal polyester.

In the liquid crystal polyester, the content ratio of the structural unit (3) in which Ar ³ is 1,4-phenylene (e.g., a structural unit derived from hydroquinone) is preferably 12.5 mol% to 30 mol%, more preferably 17.5 mol% to 30 mol%, and even more preferably 20 mol% to 25 mol%, relative to the total amount of all structural units in the liquid crystal polyester. In the liquid crystal polyester, the content ratio of the structural unit ( ^{2) in which Ar 2 is 2,6} -naphthalenediyl is preferably 0.5 mol times or more, more preferably 0.6 mol times or more, relative to the total amount of the structural units derived from 2,6-naphthalenedicarboxylic acid and the structural units derived from terephthalic acid.

The blending ratio of each structural unit relative to 100 mol% of the total amount of all structural units in the above-mentioned liquid crystal polyester may be a blending ratio relative to 100 mol% of the total amount of all structural units derived from aromatic compounds in the liquid crystal polyester. The sum of the above-mentioned structural unit contents in the liquid crystal polyester does not exceed 100 mol%.

The liquid crystal polyester of the embodiment can be produced by, for example, melt-condensing the monomers that obtain the structural units. At this time, as the aforementioned monomers, in order to quickly carry out melt-condensation, it is preferable to use their ester-forming derivatives.

Here, examples of ester-forming derivatives include compounds having a carboxyl group such as aromatic hydroxycarboxylic acids or aromatic dicarboxylic acids, wherein the carboxyl group is converted to a halogenated methyl ester group, the carboxyl group is converted to an acyloxycarbonyl group, or the carboxyl group is converted to an alkoxycarbonyl group or an aryloxycarbonyl group.

In the case of a compound having a hydroxyl group such as an aromatic hydroxycarboxylic acid or an aromatic diol, for example, a compound in which the hydroxyl group is converted to an acyloxy group can be used. Among them, a compound in which the hydroxyl group is converted to an acyloxy group is preferably used, that is, as an ester-forming derivative of an aromatic hydroxycarboxylic acid, an aromatic acyloxycarboxylic acid in which the hydroxyl group is acylated is preferably used, and as an ester-forming derivative of an aromatic diol, an aromatic diacyloxy compound in which the hydroxyl group is acylated is preferably used. Acylation preferably utilizes acetylation with acetic anhydride, and the acetylated ester-forming derivative can be deacetated and polymerized.

Melt polymerization can be carried out in the presence of a catalyst. Examples of the catalyst include metal compounds such as magnesium acetate, stannous acetate, tetrabutyl titanium, lead acetate, sodium acetate, potassium acetate, and antimony trioxide, or nitrogen-containing heterocyclic compounds such as 4-(dimethylamino)pyridine and 1-methylimidazole. Preferably, nitrogen-containing heterocyclic compounds are used. In addition, if necessary, melt polymerization can be further solid phase polymerization.

The liquid crystal polyester in the liquid crystal polyester powder of the embodiment preferably has a flow starting temperature of 250°C or higher, more preferably 250°C or higher and 350°C or lower, and even more preferably 260°C or higher and 330°C or lower. The higher the flow starting temperature of the liquid crystal polyester, the easier it is to improve the heat resistance or strength and rigidity. If it is too high, the crushing property becomes poor and it is difficult to obtain a powder of the target particle size.

The flow initiation temperature is also called the fluid temperature or the flow temperature. It is the temperature at which the liquid crystal polyester is melted by a capillary viscometer under a load of 9.8 MPa (100 kg/ ^cm2 ) while heating at a rate of 4°C/min. When the liquid crystal polyester is extruded from a nozzle with an inner diameter of 1 mm and a length of 10 mm, it displays a viscosity of 4800 Pa.s (48,000 poise). This temperature is the molecular weight standard of liquid crystal polyester (see Naoyuki Koide, "Liquid Crystal Polyester - Synthesis, Forming, and Application", CMC Co., Ltd., June 5, 1987, p. 95).

The liquid crystal polyester powder of the embodiment can be obtained by, for example, grinding a powder of a liquid crystal polyester having a number average molecular weight of 10,000 or less produced by the above-mentioned method for producing the liquid crystal polyester so that its average particle size becomes 0.5 to 20 μm by a jet mill or the like as needed.

The liquid crystal polyester powder of the embodiment may be a liquid crystal polyester powder containing a number average molecular weight of less than 10,000 and an average particle size of 0.5 to 20 μm (except for a liquid crystal polyester composed of structural units derived from 2-hydroxy-6-naphthoic acid, structural units derived from 2,6-naphthalene dicarboxylic acid, structural units derived from terephthalic acid, and structural units derived from hydroquinone, with a volume average particle size of 9 μm).

The liquid crystal polyester powder of the embodiment may be a liquid crystal polyester having a number average molecular weight of less than 10,000 and an average particle size of 0.5 to 20 μm (except for a liquid crystal polyester having a volume average particle size of 9 μm formed by a polymer obtained by reacting a mixture of 2-hydroxy-6-naphthoic acid (5.5 mol), 2,6-naphthalene dicarboxylic acid (1.75 mol), terephthalic acid (0.5 mol), hydroquinone (2.475 mol), acetic anhydride (12 mol) and 1-methylimidazole as a catalyst).

The liquid crystal polyester powder of the embodiment may be a liquid crystal polyester powder containing a number average molecular weight of less than 10,000 and an average particle size of 0.5 to 20 μm (except for a liquid crystal polyester powder having a volume average particle size of 9 μm obtained by crushing a liquid crystal polyester having a flow starting temperature of 265° C. composed of structural units derived from 2-hydroxy-6-naphthoic acid, structural units derived from 2,6-naphthalene dicarboxylic acid, structural units derived from terephthalic acid, and structural units derived from hydroquinone).

The liquid crystal polyester powder of the embodiment may be a liquid crystal polyester powder containing a number average molecular weight of less than 10,000 and an average particle size of 0.5 to 20 μm (but excluding liquid crystal polyester powder containing structural units derived from 2-hydroxy-6-naphthoic acid, structural units derived from 2,6-naphthalene dicarboxylic acid, structural units derived from terephthalic acid and structural units derived from hydroquinone and having a volume average particle size of 9 μm).

The liquid crystal polyester powder of the embodiment may be a liquid crystal polyester powder containing a number average molecular weight of less than 10,000 and an average particle size of 0.5 to 20 μm (except for a liquid crystal polyester powder having a volume average particle size of 9 μm and a polymer obtained by reacting a mixture of 2-hydroxy-6-naphthoic acid (5.5 mol), 2,6-naphthalene dicarboxylic acid (1.75 mol), terephthalic acid (0.5 mol), hydroquinone (2.475 mol), acetic anhydride (12 mol) and 1-methylimidazole as a catalyst).

The liquid crystal polyester powder of the embodiment may be a liquid crystal polyester powder containing a number average molecular weight of less than 10,000 and having an average particle size of 0.5 to 20 μm (except for a liquid crystal polyester powder having a volume average particle size of 9 μm obtained by crushing a liquid crystal polyester containing structural units derived from 2-hydroxy-6-naphthoic acid, structural units derived from 2,6-naphthalene dicarboxylic acid, structural units derived from terephthalic acid and structural units derived from hydroquinone and having a flow starting temperature of 265°C).

The liquid crystal polyester powder of the embodiment may be a liquid crystal polyester powder containing a number average molecular weight of less than 10,000 and an average particle size of 0.5 to 20 μm (except for a liquid crystal polyester powder having a volume average particle size of 9 μm obtained by reacting a mixture of 2-hydroxy-6-naphthoic acid (5.5 mol), 2,6-naphthalene dicarboxylic acid (1.75 mol), terephthalic acid (0.5 mol), hydroquinone (2.475 mol), acetic anhydride (12 mol) and 1-methylimidazole as a catalyst and having a flow starting temperature of 265°C).

The "volume average particle size" herein is measured for a dispersion of a liquid crystal polyester powder obtained by ultrasonically dispersing 0.01 g of the liquid crystal polyester powder in about 10 g of pure water for 5 minutes, using a scattering type particle size distribution measuring device (e.g., "LA-950V2" manufactured by HORIBA Co., Ltd.), with the refractive index of pure water being 1.333. The "volume average particle size" is the value of the particle size at the point where the cumulative volume becomes 50% when the total is set to 100% in the cumulative particle size distribution curve of the volume basis measured by the scattering type particle size distribution measuring device (50% cumulative volume particle size _D50 ).

In addition, acetic acid derived from acetic anhydride, which is a raw material of the liquid crystal polyester, may remain in the liquid crystal polyester powder of the embodiment, but the upper limit of the amount of residual acetic acid that can be contained in 100% by mass of the liquid crystal polyester powder of the embodiment is preferably 1% by mass or less, more preferably 500% by mass or less, and more preferably 300% by mass or less from the perspective of mechanical properties after processing into a film. In addition, the lower limit of the amount of residual acetic acid that can be contained in 100% by mass of the liquid crystal polyester powder of the embodiment is preferably 30% by mass or more, more preferably 50% by mass or more, and more preferably 100% by mass or more from the perspective of crushability. The upper limit and lower limit of the amount of residual acetic acid that can be contained in 100% by mass of the liquid crystal polyester powder can be freely combined. The amount of residual acetic acid contained in 100 mass % of the liquid crystal polyester powder may range from 30 mass ppm to 1 mass %, from 50 mass ppm to 500 mass ppm, or from 100 mass ppm to 300 mass ppm.

According to the liquid crystal polyester powder of the embodiment, a liquid crystal polyester film having a quality suitable for use as a film for electronic components can be manufactured. As a quality standard, the isotropy, thickness and appearance (whether there are holes or through holes) of the film can be cited as examples. By setting the number average molecular weight of the liquid crystal polyester in the liquid crystal polyester powder of the embodiment to a small value of 10,000 or less, the liquid crystal polyester composition becomes suitable for coating, and the melting state of the liquid crystal polyester film during heat treatment becomes good, and a liquid crystal polyester film with excellent isotropy can be manufactured, and film processing can be performed. Furthermore, by setting the average particle size of the liquid crystal polyester powder of the embodiment to 0.5~20μm, a high-quality polyester film with a thickness suitable for use as a film for electronic components and with suppressed holes or through holes can be obtained.

Liquid crystal polyester powder according to the implementation form can produce liquid crystal polyester film with excellent isotropy. In the past, liquid crystal polyester film was generally produced by melt forming or casting method in which liquid crystal polyester is melted. Melt forming is a method of forming a film by extruding a kneaded material from an extruder. However, in the film produced by the melt forming method, the liquid crystal polyester molecules are more oriented in the film forming direction (also called extrusion direction, Machine Direction (MD)) than in the transverse direction to the extrusion direction (the direction perpendicular to the extrusion direction and the film thickness direction, Transverse Direction (TD)), making it difficult to obtain liquid crystal polyester with excellent isotropy. In contrast, liquid crystal polyester powder according to the implementation form can produce liquid crystal polyester film with excellent isotropy. The liquid crystal polyester powder of the embodiment is suitable as a raw material for the manufacturing method of the liquid crystal polyester film of the embodiment. By applying the method, it is not necessary to use the above-mentioned extrusion molding operation, and a liquid crystal polyester film with excellent isotropy can be easily manufactured. Here, the so-called "excellent isotropy" of the liquid crystal polyester film means that the molecular orientation (MOR) value of the liquid crystal polyester film is in the range of 1 to 1.1.

According to the liquid crystal polyester powder of the implementation form, a liquid crystal polyester film having both dielectric properties and isotropy can be manufactured. Compared with the liquid crystal polyester film formed by the melt molding method, the liquid crystal polyester of the liquid crystal polyester film manufactured by the solution casting method is isotropic. However, when the solution casting method is applied, there is a limitation that a liquid crystal polyester having the property of being soluble in a solvent must be used. Liquid crystal polyester with high solubility in solvents may reduce dielectric properties due to, for example, increased polarity. In this way, it is difficult to have both dielectric properties and isotropy of a liquid crystal polyester film at a high level. In contrast, according to the liquid crystal polyester powder of the implementation form, a liquid crystal polyester film having both dielectric properties and isotropy can be manufactured. The liquid crystal polyester powder of the embodiment is suitable as a raw material for the method for producing the liquid crystal polyester film of the embodiment. By applying the method, it is not necessary to dissolve the liquid crystal polyester powder in a solvent, and a liquid crystal polyester film with excellent isotropy can be easily produced. In addition, since a liquid crystal polyester with excellent dielectric properties can be used as a raw material, a liquid crystal polyester film with excellent dielectric properties and isotropy can be easily produced.

<<Liquid crystal polyester composition>> The liquid crystal polyester composition of the embodiment contains a medium and liquid crystal polyester powder of the embodiment. The liquid crystal polyester composition is preferably used to produce a liquid crystal polyester film described later. The liquid crystal polyester composition of the embodiment preferably contains an aprotic solvent and a liquid crystal polyester powder insoluble in the aforementioned aprotic solvent.

The liquid crystal polyester powder may be exemplified by those described in the above-mentioned <<Liquid Crystalline Polyester Powder>>, and the description thereof will be omitted.

The medium is not particularly limited as long as it is a medium in which the liquid crystal polyester powder is insoluble, and is preferably a dispersion medium. The medium is preferably a fluid, and more preferably a liquid. The term "dispersion" here is used to distinguish it from the state in which the liquid crystal polyester powder is dissolved (except for the state in which the liquid crystal polyester powder is dissolved in the liquid crystal polyester composition). The distribution of the liquid crystal polyester powder in the composition may also be uneven. The state of the liquid crystal polyester powder in the composition is that the liquid crystal polyester composition can be coated on the support in the above-mentioned method for manufacturing the liquid crystal polyester film.

Examples of the medium include halogenated hydrocarbons such as dichloromethane, chloroform, 1,1-dichloroethane, 1,2-dichloroethane, 1,1,2,2-tetrachloroethane, 1-chlorobutane, chlorobenzene, o-dichlorobenzene, etc.; halogenated phenols such as p-chlorophenol, pentachlorophenol, pentafluorophenol, etc.; ethers such as diethyl ether, tetrahydrofuran, 1,4-dioxane, etc.; ketones such as acetone, cyclohexanone, etc.; esters such as ethyl acetate, γ-butyrolactone, etc.; carbonates such as ethyl carbonate, propyl carbonate, etc. Esters; 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; urea compounds such as tetramethylurea; nitro compounds such as nitromethane and nitrobenzene; sulfur compounds such as dimethyl sulfoxide and cyclobutane sulfone; and phosphorus compounds such as hexamethylphosphamide and tri-n-butylphosphoric acid, and two or more of these may be used.

As the medium, based on low corrosivity and easy handling, it is preferred to use an aprotic compound, especially a medium having an aprotic compound without halogen atoms as the main component. The ratio of the aprotic compound in the whole medium is preferably 50-100% by mass, more preferably 70-100% by mass, and even more preferably 90-100% by mass. In addition, as the aforementioned aprotic compound, it is preferred to use amides such as N,N-dimethylformamide, N,N-dimethylacetamide, tetramethylurea, N-methylpyrrolidone, or esters such as γ-butyrolactone, and more preferably N,N-dimethylformamide, N,N-dimethylacetamide and N-methylpyrrolidone.

Furthermore, as a medium, based on easy removal, it is preferred to use a compound having a boiling point of 220°C or less at 1 atmosphere as a main component, and the proportion of the compound having a boiling point of 220°C or less at 1 atmosphere in the entire medium is preferably 50-100 mass%, more preferably 70-100 mass%, and even more preferably 90-100 mass%. It is preferred to use a compound having a boiling point of 220°C or less at 1 atmosphere as the aforementioned aprotic compound.

The ratio of the liquid crystal polyester powder to the total solid content in the liquid crystal polyester composition can be, for example, 50-100% by mass, 70-100% by mass, or 90-100% by mass.

The ratio of the liquid crystal polyester powder contained in the liquid crystal polyester composition to the total amount of the liquid crystal polyester powder and the medium is preferably 0.1-60% by mass, more preferably 1-50% by mass, still more preferably 3-40% by mass, and particularly preferably 5-30% by mass.

The liquid crystal polyester composition can be obtained by mixing the medium, liquid crystal polyester powder and other components used as needed at once or in a proper order.

The liquid crystal polyester composition may also contain one or more fillers, additives, and other components such as resins other than liquid crystal polyester.

Examples of fillers include inorganic fillers such as silicon oxide, aluminum oxide, titanium oxide, barium titanate, strontium titanate, aluminum hydroxide, and calcium carbonate; and organic fillers such as hardened epoxy resins, crosslinked phenylguanidine resins, and crosslinked acrylic resins. The content thereof can be 0, preferably less than 100 parts by mass, relative to 100 parts by mass of liquid crystal polyester.

Examples of additives include leveling agents, defoaming agents, antioxidants, ultraviolet absorbers, flame retardants and colorants, and their content can be 0, preferably 5 parts by mass or less, relative to 100 parts by mass of the liquid crystal polyester.

Examples of resins other than liquid crystal polyesters include thermoplastic resins other than liquid crystal polyesters such as polypropylene, polyamide, polyesters other than liquid crystal polyesters, polyphenylene sulfide, polyether ketone, polycarbonate, polyether sulfide, polyphenylene ether and its modified products, polyether imide, etc.; elastomers such as copolymers of glycidyl methacrylate and polyethylene; and thermosetting resins such as phenol resins, epoxy resins, polyimide resins, and cyanate resins, and the content thereof may be 0, preferably 20 parts by mass or less, relative to 100 parts by mass of the liquid crystal polyester.

The liquid crystal polyester composition of the embodiment may contain more than 70 mass % and less than 100 mass % relative to the total mass % of the liquid crystal polyester contained, or may be 80-100 mass %. The liquid crystal polyester is exemplified in the liquid crystal polyester powder of the embodiment, but may be a liquid crystal polyester not corresponding to the following component (X) in the liquid crystal polyester described in the paragraph (liquid crystal polyester) of the embodiment, or may be, for example, a liquid crystal polyester of 1) to 4) above, or a liquid crystal polyester having the structural unit represented by the above formula (1), the structural unit represented by the above formula (2), and the structural unit represented by the above formula (3), or a liquid crystal polyester having the structural unit represented by the above formula (2) and the structural unit represented by the above formula (3).

The liquid crystal polyester composition in the embodiment may contain a medium and liquid crystal polyester powder (however, the content of the liquid crystal polyester soluble in the aprotic solvent is less than 5% by mass relative to 100% by mass of the total liquid crystal polyester).

The liquid crystal polyester composition in the embodiment may contain a medium and liquid crystal polyester powder (however, in the case of containing liquid crystal polyester powder as the resin powder, it excludes liquid crystal polyester soluble in aprotic solvent).

The liquid crystal polyester soluble in an aprotic solvent may be a liquid crystal polyester containing a structural unit derived from 4'-hydroxyacetaniline.

The liquid crystal polyester soluble in an aprotic solvent may be a liquid crystal polyester containing a structural unit derived from 6-hydroxy-2-naphthoic acid, a structural unit derived from 4'-hydroxyacetoaniline, and a structural unit derived from isophthalic acid.

The liquid crystal polyester soluble in an aprotic solvent may be a polymer obtained by reacting a mixture of 6-hydroxy-2-naphthoic acid (0.5 mol), 4'-hydroxyacetaniline (2.5 mol), isophthalic acid (2.5 mol) and acetic anhydride (8.4 mol).

The following is an explanation of liquid crystal polyesters soluble in aprotic solvents.

<<(X) ingredient>>

Component (X) is a liquid crystal polyester soluble in an aprotic solvent. Here, "soluble in an aprotic solvent" can be confirmed by performing the following test.

‧Test method

The liquid crystal polyester was stirred in an aprotic solvent at a temperature ranging from 120°C to 180°C for 1 to 6 hours, and then cooled to room temperature (23°C). Next, the residues remaining on the membrane filter were confirmed after filtering using a 5μm membrane filter and a pressure filter. At this time, if no solid matter was confirmed, it was judged to be soluble in the aprotic solvent.

More specifically, 1 part by mass of liquid crystal polyester was added to 99 parts by mass of aprotic solvent, stirred at 140°C for 4 hours, and then cooled to 23°C. Next, the mixture was filtered using a 5μm membrane filter and a pressure filter, and the residue remaining on the membrane filter was confirmed. At this time, if no solid matter was confirmed, it was judged to be soluble in the aprotic solvent.

The liquid crystal polyester (X) preferably contains structural units represented by the following formulae (X1), (X2) and (X3) as structural units.

As a point of view, relative to the total content of all structural units constituting component (X), the content of the structural unit represented by formula (X1) is 30~80 mol%, 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 unit represented by the aforementioned formula (X1), the structural unit represented by the aforementioned formula (X2), and the structural unit represented by the aforementioned formula (X3) shall not exceed 100 mol%.

(X1)-O-Ar1-CO-

(X2)-CO-Ar2-CO-

(X3)-X-Ar3-Y-

(In X1~X3, Ar1 represents 1,4-phenylene, 2,6-naphthalenediyl or 4,4'-biphenylene, Ar2 represents 1,4-phenylene, 1,3-phenylene or 2,6-naphthalenediyl, Ar3 represents 1,4-phenylene or 1,3-phenylene, X represents -NH-, and Y represents -O- or -NH-).

The structural unit (X1) is a structural unit derived from an aromatic hydroxycarboxylic acid, the structural unit (X2) is a structural unit derived from an aromatic dicarboxylic acid, and the structural unit (X3) is a structural unit derived from an aromatic diamine or an aromatic diamine having a phenolic hydroxyl group. The component (X) may also replace the above structural units with ester or amide-forming derivatives of the above structural units.

In this embodiment, preferably, Ar1 is 2,6-naphthalenediyl, Ar2 is 1,3-phenylene, Ar3 is 1,4-phenylene, and Y is -O-.

Examples of ester-forming derivatives of carboxylic acids include derivatives with high reactivity such as acyl chlorides and acid anhydrides that promote the reaction of carboxyl groups to form polyesters, and derivatives that form esters with alcohols or ethylene glycol, etc., such as carboxyl groups to form polyesters through ester exchange reactions. Examples of ester-forming derivatives of phenolic hydroxyl groups include esters formed by phenolic hydroxyl groups and carboxylic acids. Examples of amide-forming derivatives of amino groups include amides formed by amino groups and carboxylic acids.

The repeating structural unit of the component (X) used in the present embodiment can be exemplified by the following, but is not limited thereto.

Examples of structural units represented by formula (X1) include structural units derived from p-hydroxybenzoic acid, 6-hydroxy-2-naphthoic acid or 4'-hydroxy-4-biphenylcarboxylic acid, and the total structural units may contain two or more of the aforementioned structural units. Among the structural units, it is preferred to use component (X) containing structural units derived from 6-hydroxy-2-naphthoic acid. The content of structural unit (X1) is 30 mol% to 80 mol%, preferably 40 mol% to 70 mol%, and more preferably 45 mol% to 65 mol%, relative to the content of all structural units constituting component (X). When the structural unit (X1) is more, the solubility in the solvent tends to be significantly reduced, and when it is too little, the liquid crystal property tends not to be shown. That is, when the content of the structural unit (X1) is within the above range, the solubility in the solvent is good and liquid crystallinity is easily exhibited.

Examples of structural units represented by formula (X2) include structural units derived from terephthalic acid, isophthalic acid or 2,6-naphthalene dicarboxylic acid, and the total structural units may contain two or more of the aforementioned structural units. Among these structural units, liquid crystal polyesters containing structural units derived from isophthalic acid are preferably used 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%. When the structural unit (X2) is too much, the liquid crystal properties tend to decrease, and when it is too little, the solubility in solvents tends to decrease. That is, when the content of the structural unit (X2) is within the above range, the liquid crystal properties are good and the solubility in the solvent is also good.

Examples of structural units represented by formula (X3) include structural units derived from 3-aminophenol, 4-aminophenol, 1,4-phenylenediamine or 1,3-phenylenediamine, and the total structural units may contain two or more of the aforementioned structural units. Among these structural units, liquid crystal polyesters containing structural units derived from 4-aminophenol are preferably used from the viewpoint of reactivity.

The content of the structural unit (X3) is preferably 10 mol% to 35 mol% relative to the content of all structural units constituting the component (X), more preferably 15 mol% to 30 mol%, and particularly preferably 17.5 mol% to 27.5 mol%. When the structural unit (X3) is too much, the liquid crystal properties tend to be reduced, and when it is too little, the solubility in the solvent tends to be reduced. That is, if the content of the structural unit (X3) is within the above range, the liquid crystal properties become good and the solubility in the solvent is also good.

The structural unit (X3) is preferably used in substantially the same amount as the structural unit (X2), but the degree of polymerization of the liquid crystal polyester can be controlled by setting the content of the structural unit (X3) to -10 to +10 mol % relative to the content of the structural unit (X2).

The method for producing the component (X) of the present embodiment is not particularly limited, but examples thereof include a method in which an aromatic hydroxy acid corresponding to the structural unit (X1), an aromatic amine having a phenolic hydroxyl group corresponding to the structural unit (X3), or an acylate obtained by acylation of the phenolic hydroxyl group or amine group of an aromatic diamine with an excess of fatty acid anhydride, and an aromatic dicarboxylic acid corresponding to the structural unit (X2) are subjected to ester-amide exchange (polycondensation) and melt polymerization (see Japanese Patent Application Publication Nos. 2002-220444 and 2002-146003).

In the acylation reaction, the amount of fatty acid anhydride added is preferably 1.0 to 1.2 equivalents, more preferably 1.05 to 1.1 equivalents, relative to the total amount of phenolic hydroxyl groups and amine groups. When the amount of fatty acid anhydride added is too small, acylation products or raw material monomers will sublimate during ester-amide exchange (polymerization), and the reaction system will tend to be easily blocked, and when it is too large, the color of the resulting liquid crystal polyester will tend to become noticeable. That is, if the amount of fatty acid anhydride added is within the above range, the reaction of acylation products or raw material monomers during ester-amide exchange (polymerization) will be good, and the resulting liquid crystal polyester will not be overly colored.

The acylation reaction is preferably carried out at 130-180°C for 5 minutes to 10 hours, more preferably at 140-160°C for 10 minutes to 3 hours.

The fatty acid anhydride used in the acylation reaction is not particularly limited, but examples thereof include acetic anhydride, propionic anhydride, butyric anhydride, isobutyric anhydride, valeric anhydride, caproic anhydride, 2-ethylhexanoic anhydride, monochloroacetic anhydride, dichloroacetic anhydride, trichloroacetic anhydride, monobromoacetic anhydride, dibromoacetic anhydride, tribromoacetic anhydride, monofluoroacetic anhydride, difluoroacetic anhydride, trifluoroacetic anhydride, glutaric anhydride, maleic anhydride, succinic anhydride, β-bromopropionic anhydride, etc., and two or more of these can be used in combination. In the present embodiment, acetic anhydride, propionic anhydride, butyric anhydride or isobutyric anhydride is preferred, and acetic anhydride is more preferred.

In the ester-amide exchange (polycondensation), the acyl group of the acylated product is preferably 0.8 to 1.2 times the equivalent of the carboxyl group.

The ester-amide exchange (polymerization) is preferably carried out while raising the temperature to 400°C at a rate of 1-50°C/min, and more preferably carried out while raising the temperature to 350°C at a rate of 0.3-5°C/min.

When the acylated product and the carboxylic acid are subjected to ester-amide exchange (polycondensation), the by-produced fatty acid and the unreacted fatty acid anhydride are preferably evaporated and distilled out of the system.

Furthermore, the acylation reaction and ester-amide exchange (polycondensation) can also be carried out in the presence of a catalyst. As the aforementioned catalyst, those that have been known as catalysts for polyester polymerization in the past can be used, such as metal salt catalysts such as magnesium acetate, stannous acetate, tetrabutyl titanium ester, lead acetate, sodium acetate, potassium acetate, antimony trioxide, and organic compound catalysts such as N,N-dimethylaminopyridine and N-methylimidazole. Among these catalysts, heterocyclic compounds containing at least two nitrogen atoms such as N,N-dimethylaminopyridine and N-methylimidazole are preferably used (see Japanese Patent Publication No. 2002-146003). The aforementioned catalyst is usually added when the monomers are added, and there is no need to remove it after acylation. If the aforementioned catalyst is not removed, the ester exchange can be directly carried out.

The polycondensation of ester exchange and amide exchange is usually carried out by melt polymerization, but melt polymerization and solid phase polymerization can also be used together. Solid phase polymerization is preferably carried out by known solid phase polymerization methods after the melt polymerization step, after extracting the polymer, and then crushing it into powder or flakes. Specifically, for example, a method of heat treatment in a solid phase state for 1 to 30 hours at 20 to 350°C in an inert environment such as nitrogen. Solid phase polymerization can also be carried out while stirring or in a static state without stirring. In addition, by having an appropriate stirring mechanism, the melt polymerization tank and the solid phase polymerization tank can also be set as the same reaction tank. After solid phase polymerization, the obtained liquid crystal polyester can also be granulated and formed by known methods. And it can also be crushed by known methods.

The production of liquid crystal polyester can be carried out using, for example, batch equipment, continuous equipment, etc.

When the liquid crystal polyester (X) is made into powder, the volume average particle size is preferably 100~2000μm. The volume average particle size of the powdered liquid crystal polyester (X) can be measured by dry screening method (such as RPS-105 manufactured by SEISHIN Enterprise Co., Ltd.).

From one perspective, the content of component (X) is preferably 5-10% by mass relative to the total mass of the liquid crystal polyester liquid composition.

[Production example of liquid crystal polyester (X)]

In a reactor equipped with a stirring device, a torque sensor, a nitrogen inlet tube, a thermometer and a reflux cooler, 940.9 g (5.0 mol) of 6-hydroxy-2-naphthoic acid, 377.9 g (2.5 mol) of 4'-hydroxyacetaniline, 415.3 g (2.5 mol) of isophthalic acid and 867.8 g (8.4 mol) of acetic anhydride were fed. After the gas in the reactor was replaced with nitrogen, the temperature was raised from room temperature (23°C) to 140°C over 60 minutes under a nitrogen flow while stirring, and refluxed at 140°C for 3 hours. Next, the temperature was raised from 150°C to 300°C over 5 hours while removing byproduct acetic acid and unreacted acetic anhydride. After being kept at 300°C for 30 minutes, the contents were taken out of the reactor and cooled to room temperature (23°C). The obtained solid was crushed with a grinder to obtain a powdered liquid crystal polyester (X-1). The flow starting temperature of the liquid crystal polyester (X-1) was 193.3°C.

Liquid crystal polyester (X-1) was heated from room temperature (23°C) to 160°C in a nitrogen environment for 2 hours and 20 minutes, then heated from 160°C to 180°C for 3 hours and 20 minutes, and kept at 180°C for 5 hours to perform solid phase polymerization, then cooled to 23°C, and then pulverized with a pulverizer to obtain a powdered liquid crystal polyester (X-2). The flow starting temperature of the liquid crystal polyester (X-2) is 220°C.

Liquid crystal polyester (X-2) was heated from room temperature to 180°C in a nitrogen environment for 1 hour and 25 minutes, then heated from 180°C to 255°C for 6 hours and 40 minutes, and kept at 255°C for 5 hours to perform solid phase polymerization, and then cooled to 23°C to obtain a powdered liquid crystal polyester (X) with a volume average particle size of 871μm. The volume average particle size of the liquid crystal polyester (X) was measured by RPS-105 manufactured by SEISHIN Enterprise Co., Ltd. The flow starting temperature of the liquid crystal polyester (X) was 302°C.

[Preparation of liquid crystal polyester solution (X’)]

Add 8 parts by mass of liquid crystal polyester (X) to 92 parts by mass of N-methylpyrrolidone (boiling point (1 atmosphere) 204°C), stir at 140°C for 4 hours in a nitrogen environment to prepare a liquid crystal polyester solution (X'). The viscosity of the liquid crystal polyester solution (X') is 955mPa‧s.

<<Method for producing liquid crystal polyester film>

The manufacturing method of the liquid crystal polyester film of the embodiment includes coating the liquid crystal polyester composition of the embodiment on a support body, performing heat treatment, and obtaining the liquid crystal polyester film containing the liquid crystal polyester.

The manufacturing method may also include the following steps. A step of coating a liquid crystal polyester composition in an implementation form on a support to form a precursor of a liquid crystal polyester film on the support (coating step). A step of heat-treating the precursor of the liquid crystal polyester film to obtain a liquid crystal polyester film (heat-treating step).

The coating step in the method for producing a liquid crystal polyester film may include a step of removing a medium from the coated liquid crystal polyester composition (drying step) after coating the liquid crystal polyester composition in the implemented form on the support. That is, the method for producing a liquid crystal polyester film in the implemented form may also include coating the liquid crystal polyester composition in the implemented form on the support, removing the medium from the coated liquid crystal polyester composition, and performing heat treatment to obtain a liquid crystal polyester film containing liquid crystal polyester.

In addition, the method for producing the liquid crystal polyester film may further include a step of separating the support from the laminate (separation step). In addition, the liquid crystal polyester film may be preferably used as a film for electronic components in a state where the laminate is formed on the support, so the separation step is not an essential step in the production step of the liquid crystal polyester film.

The following reference figures illustrate an example of a method for manufacturing a liquid crystal polyester film according to an embodiment.

FIG1 is a schematic diagram showing an example of the manufacturing process of the liquid crystal polyester film and laminate in the implementation form. First, the liquid crystal polyester composition 30 is coated on the support 12 (FIG1(a) coating step). The liquid crystal polyester composition 30 contains liquid crystal polyester powder 1 and medium 3. The coating of the liquid crystal polyester composition on the support can be carried out by roller coating, immersion coating, spray coating, rotary coating, curtain coating, slit coating and screen printing. A method that can coat the surface of the support smoothly and uniformly can be appropriately selected. Furthermore, in order to make the distribution of the liquid crystal polyester powder uniform, the liquid crystal polyester composition may be stirred before coating.

The support 12 is preferably in the shape of a plate, sheet or film, and examples thereof include a glass plate, a resin film or a metal foil. Among them, resin films or metal foils are preferred, especially due to their excellent heat resistance, ease of coating of liquid compositions, and ease of removal from liquid crystal polyester films, and copper foils are preferred. Examples of commercially available polyimide (PI) films include "U-PILEX S" and "U-PILEX R" from Ube Industries, "KAPTON" from DuPont Toray, and "IF30", "IF70" and "LV300" from SKC KOLON PI. The thickness of the resin film is preferably 25 μm to 75 μm, and 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.

Next, the medium 3 is removed from the liquid crystal polyester composition 30 coated on the support 12 (drying step in FIG. 1(b)). The liquid crystal polyester composition from which the medium 3 is removed becomes the liquid crystal polyester film precursor 40 to be subjected to heat treatment. Furthermore, the medium 3 does not have to be completely removed from the liquid crystal polyester composition, and a portion of the medium contained in the liquid crystal polyester composition may be removed, or the medium may be completely removed. The ratio of the solvent 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, relative to the total mass of the liquid crystal polyester film precursor. By making the solvent content in the liquid crystal polyester film precursor above the above lower limit, the risk of reduced thermal conductivity of the liquid crystal polyester film can be reduced. Furthermore, by making the solvent content in the liquid crystal polyester film precursor below the above upper limit, the risk of degradation of the appearance of the liquid crystal polyester film due to foaming during heat treatment can be reduced.

The removal of the medium is preferably performed by evaporating the medium, and examples of such methods include heating, decompression and ventilation, and these methods may also be combined. In addition, the removal of the medium may be performed continuously or in a single piece. From the perspective of productivity and operability, the removal of the medium is preferably performed by continuous heating, and more preferably by continuous heating while ventilation. The temperature for removing the medium is preferably a temperature below the melting point of the liquid crystal polyester powder, for example, from 40°C to 200°C, and preferably from 60°C to 200°C. The time for removing the medium is appropriately adjusted, for example, so that the medium content in the liquid crystal polyester film precursor becomes 3 to 12% by mass. The time for removing the medium is, for example, from 0.2 hours to 12 hours, and preferably from 0.5 hours to 8 hours.

The laminate precursor 22 having the support 12 and the liquid crystal polyester film precursor 40 thus obtained is heat-treated to obtain a laminate 20 having the support 12 and the liquid crystal polyester film 10 (the film after the liquid crystal polyester film precursor 40 is heat-treated) (Figure 1 (c) heat-treatment step). At this time, the liquid crystal polyester film 10 formed on the support is obtained. The heat treatment conditions can be exemplified by, for example, heating from -50°C, the boiling point of the medium, to reach the heat treatment temperature, and then heat-treating at a temperature above the melting point of the liquid crystal polyester. During the temperature rise, the polymerization reaction of the liquid crystal polyester may be carried out by heating, but by accelerating the temperature rise rate to the heat treatment temperature, the increase in the molecular weight of the liquid crystal polyester in the liquid crystal polyester powder can be suppressed to a certain extent, so that the melting of the liquid crystal polyester powder becomes good, and a high-quality film can be easily obtained. The temperature rise rate from -50°C, the boiling point of the medium, to the heat treatment temperature is preferably 3°C/minute or more, and more preferably 5°C/minute or more. The heat treatment temperature is preferably above the melting point of the liquid crystal polyester, and more preferably a temperature higher than the melting point of the liquid crystal polyester, and more preferably a temperature of the melting point of the liquid crystal polyester + 5°C or more is set as the heat treatment temperature. The heat treatment temperature can be appropriately set according to the type of liquid crystal polyester, but as an example, it is preferably 230°C or more and 400°C or less, more preferably 300°C or more and 380°C or less, and more preferably 320°C or more and 350°C or less. By heat treating at a temperature higher than the melting point of the liquid crystal polyester, the liquid crystal polyester powder can be melted well, and a high-quality 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. In addition, the boiling point of the medium here refers to the boiling point under pressure during heating. In addition, when the heating of the laminate precursor 22 starts from -50°C, which is not the melting point of the medium, the heating rate can be determined within the range from -50°C, which is the melting point of the medium, to the heat treatment temperature. The time until the melting point of the medium is -50°C is reached is arbitrary. In addition, the time after the heat treatment temperature is reached can be considered as the heat treatment time. The heat treatment time may be, for example, 0.5 hours or longer, 1 hour or longer and 24 hours or shorter, or 3 hours or longer and 12 hours or shorter.

Heat treatment, like media removal, can be performed in a continuous manner or in a single-chip manner. However, from the perspective of productivity and operability, it is preferably performed in a continuous manner, and more preferably, performed in a continuous manner following media removal.

Next, by separating the liquid crystal polyester film 10 from the laminate 20 having the support 12 and the liquid crystal polyester film 10, the liquid crystal polyester film 10 can be obtained as a single-layer film (separation step in FIG. 1(d)). When a glass plate is used as the support 12, the liquid crystal polyester film 10 can be separated from the laminate 20 by simply peeling off the liquid crystal polyester film 10 from the laminate 20. When a resin film is used as the support 12, the separation can be performed by simply peeling off the resin film or the liquid crystal polyester film 10 from the laminate 20. When a metal foil is used as the support 12, the separation can be performed by simply removing the metal foil by etching. If a resin film, especially a polyimide film, is used as a support, it is easy to peel off the polyimide film or liquid crystal polyester film from the laminate 20, and a liquid crystal polyester film with good appearance is obtained. In the case of using a metal foil as a support, the liquid crystal polyester film can be used as a metal copper laminate for a printed wiring board without separating the liquid crystal polyester film from the laminate 20.

According to the manufacturing method of the liquid crystal polyester film of the embodiment, a liquid crystal polyester film with excellent isotropy can be manufactured. The liquid crystal polyester film is manufactured by the conventional melt forming method by forming the melted liquid crystal polyester into a film. However, the manufacturing method of the embodiment is different from the conventional film manufacturing method in that the liquid crystal polyester powder is pre-arranged on the support and then melted. According to the manufacturing method of the liquid crystal polyester film or laminate of the embodiment, the liquid crystal polyester powder is pre-arranged thinly on the support and made into a film. Therefore, the physical force that causes the segregation of the molecular orientation in extrusion molding, etc. is not applied, and a liquid crystal polyester film with excellent isotropy can be manufactured. Furthermore, by making the number average molecular weight of the aforementioned liquid crystal polyester in the liquid crystal polyester powder a relatively small value of 10,000 or less, the liquid crystal polyester composition becomes suitable for coating, and the melting state of the liquid crystal polyester film during heat treatment becomes good, and a high-quality liquid crystal polyester film with excellent isotropy suitable for use as a film for electronic parts can be produced. Furthermore, by using a liquid crystal polyester powder with an average particle size of 0.5 to 20 μm as a raw material, a high-quality polyester film with a thickness suitable for use as a film for electronic parts and suppressed pores or through holes can be easily produced. Moreover, in the liquid crystal polyester composition, since there is no restriction that the liquid crystal polyester powder should be soluble in the medium, a liquid crystal polyester with excellent dielectric properties can be used, and a liquid crystal polyester film with excellent dielectric properties and isotropy can be easily obtained.

<< Manufacturing method of laminated body>> The manufacturing method of the laminated body of the embodiment comprises coating the liquid crystal polyester composition of the embodiment on a support body, performing heat treatment to form a liquid crystal polyester film containing liquid crystal polyester, and obtaining a laminated body having the aforementioned support body and the aforementioned liquid crystal polyester film.

The manufacturing method may also include the following steps. A step of coating a liquid crystal polyester composition in an implementation form on a support to form a liquid crystal polyester film precursor on the support (coating step). A step of subjecting the aforementioned liquid crystal polyester film precursor to heat treatment to obtain a laminate having the aforementioned support and the aforementioned liquid crystal polyester film (heat treatment step).

Similar to the above-mentioned method for producing a liquid crystal polyester film, the coating step in the method for producing a laminate may also include a step of removing a medium from the coated liquid crystal polyester composition (drying step) after coating the liquid crystal polyester composition in the implemented form on the support. That is, the method for producing a laminate in the implemented form may also include coating the liquid crystal polyester composition in the implemented form on the support, removing the medium from the coated liquid crystal polyester composition, and performing heat treatment to form a liquid crystal polyester film containing a liquid crystal polyester, thereby obtaining a laminate having the aforementioned support and the aforementioned liquid crystal polyester film.

Fig. 1 is a schematic diagram showing an example of a method for manufacturing a liquid crystal polyester film and a laminate. In the method for manufacturing a laminate shown in Fig. 1, except that the above-mentioned separation step (Fig. 1(d)) is not performed, it is the same as the description in the above-mentioned "Method for Manufacturing Liquid Crystal Polyester Film" and therefore the description is omitted.

According to the manufacturing method of the laminate of the embodiment, a laminate of the liquid crystal polyester film having the embodiment can be manufactured.

<<Film>> In the above-mentioned method for manufacturing liquid crystal polyester film or laminate, although liquid crystal polyester powder is used as a raw material, a film with excellent dielectric properties and isotropy can be obtained by using a thermoplastic resin with excellent dielectric properties as a raw material instead of liquid crystal polyester.

FIG. 2 is a schematic diagram showing the structure of the film 11 of an embodiment.

The film of the embodiment includes a thermoplastic resin, and the relative permittivity at a frequency of 1 GHz is less than 3, the dielectric tangent at a frequency of 1 GHz is less than 0.005, and the molecular orientation (MOR) value measured by a microwave orientation meter is in the range of 1 to 1.1. The film that meets the above requirements has a suitable quality as a film for electronic components. As the quality standard, the above relative permittivity, dielectric tangent and molecular orientation (isotropy of the film) are considered, and the thickness and appearance (whether there are holes or through holes) are also considered. As an example, the relative permittivity and dielectric tangent values of the film can be controlled according to the type of thermoplastic resin. And as an example, the degree of isotropy of the film can be controlled by the film manufacturing method.

The relative capacitance of the film of the embodiment at a frequency of 1 GHz is 3 or less, preferably 2.9 or less, more preferably 2.8 or less, still more preferably 2.7 or less, and particularly preferably 2.6 or less. Moreover, the relative capacitance of the film may be 2.3 or more, 2.4 or more, or 2.5 or more. The upper limit and lower limit of the relative capacitance of the film may be freely combined. As an example of the numerical range of the relative capacitance of the film, it may be 2.3 or more and 3 or less, 2.4 or more and 2.9 or less, 2.5 or more and 2.8 or less, 2.5 or more and 2.7 or more, or 2.5 or more and 2.6 or less.

The dielectric tangent of the film in the embodiment at a frequency of 1 GHz is 0.005 or less, preferably 0.004 or less, more preferably 0.003 or less, still more preferably 0.002 or less, and particularly preferably 0.001 or less. The dielectric tangent of the liquid crystal polyester film may be 0.0003 or more, 0.0005 or more, or 0.0007 or more. The upper limit and lower limit of the dielectric tangent of the above film may be freely combined. As an example of the numerical range of the dielectric tangent of the above film, 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. The relative capacitance and dielectric tangent of the film at a frequency of 1 GHz can be measured by the capacitance method using an impedance analyzer under the following conditions. The film was melted at 350°C using a flow tester and then cooled and solidified to produce a tablet with a diameter of 1 cm and a thickness of 0.5 cm. The relative capacitance and dielectric tangent of the obtained tablet at 1 GHz were measured under the following conditions. ・Measurement method: capacitance method ・Electrode type: 16453A ・Measurement environment: 23°C, 50%RH ・Applied voltage: 1V

The molecular orientation ratio (MOR) of the film of the embodiment measured by a microwave orienter is in the range of 1-1.1, preferably in the range of 1-1.08, more preferably in the range of 1-1.06, and even more preferably in the range of 1-1.04.

The molecular orientation ratio (MOR) is measured by a microwave molecular orientation meter (e.g., MOA-5012A manufactured by Oji Instruments Co., Ltd.). The microwave molecular orientation meter is a device that uses different microwave transmission intensities in the orientation direction and the right-angle direction according to the molecular orientation. Specifically, the sample is rotated while being irradiated with microwaves of a certain frequency (12GHz is used), and the intensity of the transmitted microwaves that changes due to the molecular orientation is measured, and the ratio of the maximum value to the minimum value is set as the MOR. The interaction between the microwave electric field of a certain frequency and the dipoles that constitute the molecules is related to the vector product of the two. Due to the anisotropy of the sample's dielectric constant, the microwave intensity changes with the angle at which the sample is configured, so the orientation ratio can be known.

The linear expansion coefficient of the film of the embodiment is preferably 85ppm/℃ or less, more preferably 50ppm/℃ or less, still more preferably 40ppm/℃ or less, and particularly preferably 30ppm/℃ or less under the condition of a heating rate of 5℃/min. The lower limit of the linear expansion coefficient is not particularly limited, but for example, it is 0ppm/℃ or more. And for example, in the case where copper foil and film are laminated, since the linear expansion coefficient of copper foil is 18ppm/℃, the linear expansion coefficient of the film of the embodiment is preferably close to the value thereof. That is, the linear expansion coefficient of the film of the embodiment is preferably 0ppm/℃ or more and 50ppm/℃ or less, more preferably 10ppm/℃ or more and 40ppm/℃ or less, and still more preferably 20ppm/℃ or more and 30ppm/℃ or less. The linear expansion coefficient varies depending on the film direction or location, and the higher value is used as the linear expansion coefficient of the film. The linear expansion coefficient of the film can be measured using a thermomechanical analyzer (e.g., RIGAKU Co., Ltd., model: TMA8310). The film of the embodiment that meets the above numerical range has a low linear expansion coefficient and high dimensional stability.

A film with excellent isotropy is one with a smaller difference in linear expansion coefficients in the measured directions. In the above linear expansion coefficients of the film in the implementation form, the difference between the linear expansion coefficients in MD and TD (MD-TD when MD>TD, TD-MD when TD>MD) is preferably 2ppm/℃ or less, and more preferably 1ppm/℃ or less. For films formed by casting, the so-called MD is the coating direction of the dispersion. The calculation of the above difference in linear expansion coefficients is actually only required to determine the linear expansion coefficients in different directions. Therefore, when the MD and TD of the film are unknown, the direction can be set in such a way that the difference in linear expansion coefficients in the individual directions becomes the largest when an arbitrary direction of the film is set as MD and the direction intersecting it by 90° is set as TD. The film having the embodiment satisfying the above numerical range has excellent isotropy of linear expansion and high dimensional stability in the longitudinal and transverse directions.

The film of the embodiment has a suitable appearance as a film for electronic parts, and preferably has no holes or through holes. If there are holes or through holes, there is a possibility that the plating liquid will penetrate into the holes or through holes during plating. The liquid crystal polyester film made of liquid crystal polyester powder as a raw material in the embodiment has a suitable thickness as a film for electronic parts and has high quality with the occurrence of holes or through holes suppressed.

The thickness of the film in the embodiment is not particularly limited, but the preferred thickness for the film for electronic components is preferably 5 to 50 μm, more preferably 7 to 40 μm, still more preferably 10 to 33 μm, and particularly preferably 15 to 20 μm. In addition, in this specification, the so-called "thickness" is the average value of the thickness of 10 randomly selected locations measured in accordance with JIS standard (K7130-1992).

By selecting a raw material resin having excellent dielectric properties made of any thermoplastic resin, a film having excellent dielectric properties can be obtained.

The content of the thermoplastic resin can be 50-100% by mass, or 80-95% by mass, relative to the total mass of the film of the embodiment of 100% by mass.

Examples of the thermoplastic resin include polypropylene, polyamide, polyester, polysulfone, polyphenylene sulfide, polyether ketone, polycarbonate, polyphenylene ether, and polyetherimide.

Liquid crystal polyester is preferably used as the thermoplastic resin because of its particularly excellent dielectric properties. The above-mentioned description of <<Liquid crystal polyester powder>> can be used as an example for liquid crystal polyester, and the description is omitted. The content ratio of liquid crystal polyester can be 50-100% by mass or 80-95% by mass relative to the total mass of the film in the embodiment of 100% by mass.

When the film of the embodiment includes a liquid crystal polyester, the liquid crystal polyester of the embodiment may contain more than 70 mass % and less than 100 mass %, or may contain 80-100 mass %, relative to 100 mass % of the total liquid crystal polyester contained in the film. The liquid crystal polyester may be exemplified by the liquid crystal polyester powder of the embodiment described above, such as the liquid crystal polyester of 1) to 4) above, or a liquid crystal polyester having a structural unit represented by the above formula (1), a structural unit represented by the above formula (2), and a structural unit represented by the above formula (3), or a liquid crystal polyester having a structural unit represented by the above formula (2) and a structural unit represented by the above formula (3).

The film of the embodiment can be the following film: containing a thermoplastic resin, having a relative permittivity of less than 3 at a frequency of 1 GHz, a dielectric tangent of less than 0.005 at a frequency of 1 GHz, and a molecular orientation (MOR) value measured by a microwave orientation meter in the range of 1 to 1.1 (but when containing liquid crystal polyester as the thermoplastic resin, the content of liquid crystal polyester soluble in aprotic solvents is less than 5 mass% relative to 100 mass% of the total amount of liquid crystal polyester.

The film of the embodiment can be the following film: comprising a thermoplastic resin, having a relative permittivity of less than 3 at a frequency of 1 GHz, a dielectric tangent of less than 0.005 at a frequency of 1 GHz, and a molecular orientation ratio (MOR) value measured by a microwave orientation meter in the range of 1 to 1.1 (but excluding liquid crystal polyesters soluble in aprotic solvents).

Here, as the liquid crystal polyester soluble in the aprotic solvent, there can be cited those exemplified in the liquid crystal polyester powder of the embodiment.

The method for producing the film of the embodiment is not particularly limited, but the film of the embodiment can be produced by the above-mentioned <<Method for producing a liquid crystal polyester film>>. In the above-mentioned <<Method for producing a liquid crystal polyester film>>, although the liquid crystal polyester is described in detail as a raw material, in this method, by replacing the liquid crystal polyester with any thermoplastic resin, a film of the embodiment containing any thermoplastic resin can be produced.

The film of the embodiment can be preferably used as a film for electronic components such as printed wiring boards. The film of the embodiment can be provided as a substrate (such as a flexible substrate) or a laminate (such as a flexible copper laminate) having the film as an insulating material, a printed substrate, a printed wiring board, a printed circuit board, etc.

<<Laminate>> The laminate of the embodiment has a metal layer and a thin film of the embodiment laminated on the metal layer. Fig. 3 is a schematic diagram showing the structure of a laminate 21 of an embodiment of the present invention. The laminate 21 has a metal layer 13 and a thin film 11 laminated on the metal layer 13. The thin film of the laminate is exemplified by the above-mentioned examples, and the description thereof is omitted. The metal layer of the laminate is exemplified by the above-mentioned <<Method for producing liquid crystal polyester film>> and <<Method for producing laminate>> as a support, preferably a metal foil. As the metal constituting the metal layer, copper foil is preferably used as the metal foil from the viewpoint of electrical conductivity or cost.

The thickness of the laminate in the embodiment is not particularly limited, but is preferably 5 to 130 μm, more preferably 10 to 70 μm, and even more preferably 15 to 60 μm.

The manufacturing method of the laminate of the embodiment is not particularly limited, but the laminate of the embodiment can be manufactured by the above-mentioned <<manufacturing method of laminate>>. In the above-mentioned <<manufacturing method of laminate>>, it is described in detail that liquid crystal polyester is used as a raw material, but in this method, by replacing the liquid crystal polyester with an arbitrary thermoplastic resin, a laminate of the embodiment having a film containing an arbitrary thermoplastic resin can be manufactured.

The multilayer body of the embodiment can be preferably used as a thin film for electronic components such as printed wiring boards. [Example]

Next, embodiments are shown to illustrate the present invention in more detail, but the present invention is not limited to the following embodiments.

<Measurement method> [Measurement of the flow initiation temperature of liquid crystal polyester] Using a flow tester ("CFT-500" produced by Shimadzu Corporation), about 2 g of liquid crystal polyester was filled in a cylinder mounted on a nozzle having an inner diameter of 1 mm and a length of 10 mm. The liquid crystal polyester was melted while being heated at a rate of 4°C/min under a load of 9.8 MPa (100 kg/ ^cm2 ). The liquid crystal polyester was extruded from the nozzle and the temperature (FT) at which the viscosity of 4800 Pa.s (48000P) was measured.

[Determination of melting point of liquid crystal polyester] Using a differential scanning calorimeter (DSC-50 from Shimadzu Corporation), the temperature was raised at a rate of 10°C/min to confirm the position of the endothermic peak, and the temperature at the top of the endothermic peak was determined as the melting point of the liquid crystal polyester.

[Determination of molecular weight of liquid crystal polyester contained in liquid crystal polyester microparticle powder] The molecular weight of liquid crystal polyester was determined using a gel permeation chromatography-multi-angle light scattering photometer (differential refractometer (Shimadzu Corporation: RID-20A), multi-angle light scattering detector (EOS, Wyatt Technology), column (Showa Denko: Shodex K-G, K-806M (2 pieces), K-802 (1 piece) (φ8.0mm×30cm)), solvent (pentafluorophenol/chloroform (weight ratio 35/65)), the number average molecular weight of the liquid crystal polyester contained in the liquid crystal polyester microparticle powder was measured. The test sample solution was prepared by adding 2 mg of the sample to 1.4 g of pentafluorophenol, dissolving it at 80°C for 2 hours, cooling it to room temperature, adding 2.6 g of chloroform, and further diluting it twice with the solvent (pentafluorophenol/chloroform (weight ratio 35/65)), and filtering it with a filter with a pore size of 0.45μm.

[Analysis of residual acetic acid in liquid crystal polyester microparticle powder] The residual acetic acid in liquid crystal polyester microparticle powder was analyzed using a headspace gas chromatograph (Shimadzu Corporation: GC-2014) under extraction conditions of 120°C for 20 hours and analysis conditions of 200°C for 1 hour.

[Measurement of relative capacitance and dielectric tangent of liquid crystal polyester microparticle powder] The liquid crystal polyester microparticle powder was melted at a temperature 5°C higher than the melting point measured by a flow tester ("CFT-500" from Shimadzu Corporation), and then cooled and solidified to prepare a tablet with a diameter of 1 cm and a thickness of 0.5 cm. The relative capacitance and dielectric tangent of the obtained tablet were measured at 1 GHz under the following conditions. ・Measurement method: capacitance method (device: impedance analyzer (Agilent model: E4991A)) ・Electrode type: 16453A ・Measurement environment: 23°C, 50%RH ・Applied voltage: 1V

[Measurement of average particle size of liquid crystal polyester microparticle powder] Weigh 0.01 g of liquid crystal polyester microparticle powder and disperse it in about 10 g of pure water. The prepared dispersion of liquid crystal polyester microparticle powder is dispersed by ultrasound for 5 minutes. Using a scattering particle size distribution measuring device (HORIBA Co., Ltd. "LA-950V2"), the volume-based cumulative particle size distribution of the liquid crystal polyester microparticle powder is measured with the refractive index of pure water as 1.333, and the average particle size (D ₅₀ ) is calculated.

[Measurement of relative capacitance and dielectric tangent of liquid crystal polyester film] The liquid crystal polyester film was melted at 350°C using a flow tester ("CFT-500" from Shimadzu Corporation) and then cooled to solidify, thereby preparing a tablet with a diameter of 1 cm and a thickness of 0.5 cm. The relative capacitance and dielectric tangent of the obtained tablet were measured at 1 GHz under the following conditions. ・Measurement method: capacitance method (device: impedance analyzer (Agilent model: E4991A)) ・Electrode type: 16453A ・Measurement environment: 23°C, 50%RH ・Applied voltage: 1V

[Measurement of molecular orientation of liquid crystal polyester film] The film was cut into 5 cm squares and placed on a holder. The molecular orientation was measured using a molecular orientation meter (manufactured by Oji Instruments Co., Ltd., model: MOA-5012A) at a frequency of 12 GHz and a rotation speed of 1 rpm.

[Measurement of linear expansion coefficient of liquid crystal polyester film] The linear expansion coefficient was measured at a heating rate of 5°C/min from 50°C to 100°C using a thermomechanical analyzer (RIGAKU Co., Ltd., model: TMA8310). The measurement was performed in the running direction (MD) and the perpendicular direction (TD) of the liquid crystal polyester film. In addition, in the liquid crystal polyester film of each embodiment or comparative example formed by the casting method, the running direction (MD) was set as the coating direction of the dispersion.

<Production of Liquid Crystal Polyester Microparticle Powder> [Example 1] ・Production of Liquid Crystal Polyester (A) Into a reactor equipped with a stirrer, a torque sensor, a nitrogen inlet pipe, a thermometer and a reflux cooler, 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 relative to 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 fed. After the gas in the reactor was replaced with nitrogen, the temperature was raised from room temperature to 145°C in 15 minutes while stirring under nitrogen flow, and refluxed at 145°C for 1 hour. Secondly, while removing the by-product acetic acid and unreacted acetic anhydride, the temperature was raised from 145°C to 310°C in 3 hours and 30 minutes, and after being kept at 310°C for 3 hours, the solid liquid crystal polyester was taken out and cooled to room temperature to obtain liquid crystal polyester (A). The flow starting temperature of the liquid crystal polyester (A) was 268°C. The liquid crystal polyester (A) was crushed with a cutting mill VM-16 manufactured by ORIENT Pulverizer (Co., Ltd.) to obtain a liquid crystal polyester (A) powder with an average particle size of 394μm.

・Production of liquid crystal polyester microparticle powder Next, a jet mill ("KJ-200" manufactured by Kurimoto Iron Works, grinding nozzle diameter: 4.5 mm) was used to grind the powder of liquid crystal polyester (A) at a graded drum rotation speed of 10,000 rpm, a grinding nozzle pressure of 0.64 MPa, and a processing speed of 2.1 kg/hour to obtain the liquid crystal polyester microparticle powder of Example 1. The average particle size of the liquid crystal polyester microparticle powder was 8 μm. In addition, the melting point of the liquid crystal polyester microparticle powder of Example 1 was measured using a differential scanning calorimeter and the result was 290°C.

[Example 2] Except that the processing conditions of the jet mill ("KJ-200" manufactured by Kurimoto Iron Works) were set to 10,000 rpm of the graded drum rotation speed, 0.63 MPa of the pulverizing nozzle pressure, and 2.6 kg/hour of the processing speed, the liquid crystal polyester fine particle powder of Example 2 was obtained in the same manner as the preparation of the liquid crystal polyester fine particle powder of Example 1. The average particle size of the liquid crystal polyester fine particle powder was 10 μm.

[Example 3] Except that the processing conditions of the jet mill ("KJ-200" manufactured by Kurimoto Iron Works) were set to 10,000 rpm of graded drum rotation, 0.60 MPa of pulverizing nozzle pressure, and 4.0 kg/hour of processing speed to pulverize the liquid crystal polyester powder, the liquid crystal polyester fine particle powder of Example 3 was obtained in the same manner as the preparation of the liquid crystal polyester fine particle powder of Example 1. The average particle size of the liquid crystal polyester fine particle powder was 15 μm.

[Comparative Example 1] The liquid crystal polyester fine particle powder of Comparative Example 1 was obtained in the same manner as in Example 1 except that a freeze-impact mill (LINREX MILL manufactured by HOSKAWA) was used instead of a jet mill to pulverize the liquid crystal polyester powder at a processing speed of 10 kg/hour. The average particle size of the liquid crystal polyester fine particle powder was 27 μm.

[Comparative Example 2] ・Production of Liquid Crystal Polyester (D) The powder of the liquid crystal polyester (A) obtained in Example 1 was filled on a SUS plate and heat treated at 290°C for 6 hours to obtain a liquid crystal polyester (D).

・Production of liquid crystal polyester microparticle powder Next, the liquid crystal polyester microparticle powder of Comparative Example 2 was obtained in the same manner as in the production of the liquid crystal polyester microparticle powder of Example 1, except that the liquid crystal polyester microparticle powder was pulverized using a jet mill ("KJ-200" manufactured by Kurimoto Iron Works) with the settings of 10,000 rpm for the rotation of the graded drum, 0.60 MPa for the pulverizing nozzle pressure, and 0.1 kg/hour for the processing speed. The average particle size of the liquid crystal polyester microparticle powder was 7 μm.

The relative permittivity and dielectric tangent of each of the obtained liquid crystal polyester microparticle powders were measured.

Table 1 shows the above items and their test results.

<Production of liquid crystal polyester film> [Examples 1-1 to 3-1, Comparative Examples 1-1 to 2-1] ・Preparation of dispersion liquid 8 parts by weight of each liquid crystal polyester fine particle powder of Examples 1 to 3 and Comparative Examples 1 to 2 were added to 92 parts by weight of N-methyl-2-pyrrolidone (boiling point (1 atmosphere) 204°C), and stirred using a stirring degassing machine AR-500 manufactured by TKINKY Co., Ltd. to obtain each dispersion liquid.

・Manufacturing of liquid crystal polyester film Using a thin film applicator with a micrometer (SHEEN "SA204") and an automatic coating device (TESTER Industrial Co., Ltd. "I Type"), the above dispersions were cast on the roughened surface of a copper foil (Mitsui Metal Mining Co., Ltd. 3EC-VLP 18μm) in such a way that the thickness of the cast film became 300μm, and then dried at 40°C and normal pressure (1 atmosphere) for 4 hours to remove the solvent from the cast film. Regarding Comparative Example 2-1, the dispersion became gel-like and could not be cast, and could not be made into a thin film.

After the drying, the film was heated from room temperature to 310°C at 7°C/min in a hot air oven under a nitrogen atmosphere and kept at the temperature for 6 hours to obtain a liquid crystal polyester film with copper foil.

The obtained liquid crystal polyester film with copper foil was immersed in an aqueous solution of ferric chloride, and the copper foil was etched away to obtain a single-layer film. The appearance of each film was confirmed. The liquid crystal polyester film of Comparative Example 1-1 had many holes on the surface and a poor appearance, which was not suitable for the film used for electronic components.

Table 1 shows the above items and their measurement results.

Comparative Example 2-1, which uses the liquid crystal polyester microparticle powder of Comparative Example 2 containing a liquid crystal polyester having a number average molecular weight of less than 10,000 as a raw material, cannot produce a liquid crystal polyester film. In contrast, the liquid crystal polyester microparticle powders of Examples 1 to 3 containing a liquid crystal polyester having a number average molecular weight of less than 10,000 as a raw material can produce liquid crystal polyester films of Examples 1-1 to 3-1. Moreover, the liquid crystal polyester film of Comparative Example 1-1, which is produced using the liquid crystal polyester microparticle powder of Comparative Example 1 not satisfying the average particle size range of 0.5 to 20 μm as a raw material, has many holes on the surface and a poor appearance. In contrast, the liquid crystal polyester films of Examples 1-1 to 3-1 produced using the liquid crystal polyester fine particle powders of Examples 1 to 3 having an average particle size of 0.5 to 20 μm as raw materials are thinner and have excellent appearance. The appearance evaluation results of the liquid crystal polyester films of Examples 1-1 to 3-1 and Comparative Example 1-1 are as follows: those with no voids and excellent appearance are recorded as "G" in Table 1, and those with many voids and poor appearance are recorded as "F".

<Production of Liquid Crystal Polyester Film> The liquid crystal polyester fine particle powder of the liquid crystal polyester (A) obtained in the above-mentioned Example 1 was used as a raw material, and the heat treatment conditions were changed to produce the liquid crystal polyester films of Examples 1-1 to 1-5. In addition, the liquid crystal polyester film of Example 1-1 was obtained by the same production method as that of the above-mentioned Example 1-1.

[Example 1-1] ・Preparation of dispersion 8 parts by mass of the liquid crystal polyester fine particle powder of the liquid crystal polyester (A) obtained in Example 1 above was added to 92 parts by mass of N-methyl-2-pyrrolidone, and stirred using a stirring defoamer AR-500 manufactured by TKINKY Co., Ltd. to obtain each dispersion.

・Manufacturing of liquid crystal polyester film Using a thin film applicator with a micrometer (SA204 from Sheen) and an automatic coating device (Type I from Tester Industries, Ltd.), the above dispersions were cast on the roughened surface of a copper foil (3EC-VLP 18μm manufactured by Mitsui Metal Mining Co., Ltd.) in such a way that the thickness of the cast film became 300μm, and then dried at 40°C and normal pressure (1 atmosphere) for 4 hours to remove the solvent from the cast film. After the above drying, the temperature was further raised from room temperature to 310°C at 7°C/min in a hot air oven under a nitrogen environment, and the temperature was maintained for 6 hours for heat treatment to obtain the liquid crystal polyester film with copper foil of Example 1-1.

[Example 1-2] Except that the heat treatment conditions are set to 7°C/min from room temperature to 330°C, the liquid crystal polyester film with copper foil of Example 1-2 is obtained in the same manner as the preparation of the liquid crystal polyester film with copper foil of Example 1-1.

[Example 1-3] Except that the heat treatment conditions are set to 4°C/min from room temperature to 310°C, the liquid crystal polyester film with copper foil of Example 1-3 is obtained in the same manner as the preparation of the liquid crystal polyester film with copper foil of Example 1-1.

[Example 1-4] Except that the heat treatment conditions are set to 7°C/min from room temperature to 300°C, the liquid crystal polyester film with copper foil of Example 1-4 is obtained in the same manner as the preparation of the liquid crystal polyester film with copper foil of Example 1-1.

[Example 1-5] Except that the heat treatment conditions are set to 3°C/min from room temperature to 310°C, the liquid crystal polyester film with copper foil of Example 1-5 is obtained in the same manner as the preparation of the liquid crystal polyester film with copper foil of Example 1-1.

[Comparison Example 3]

Liquid crystal polyester soluble in organic solvents is manufactured and used as raw material to manufacture the liquid crystal polyester film of Comparative Example 3 as follows.

‧Manufacturing of Liquid Crystal Polyester (B)

In a reactor equipped with a stirring device, a torque sensor, a nitrogen inlet tube, a thermometer and a reflux cooler, 940.9g (5.0 mol) of 6-hydroxy-2-naphthoic acid, 377.9g (2.5 mol) of 4'-hydroxyacetaniline, 415.3g (2.5 mol) of isophthalic acid and 867.8g (8.4 mol) of acetic anhydride were fed. After the gas in the reactor was replaced with nitrogen, the temperature was raised from room temperature to 140°C in 60 minutes under a nitrogen flow while stirring, and refluxed at 140°C for 3 hours.

Next, the temperature was raised from 150°C to 300°C over 5 hours while removing byproduct acetic acid and unreacted acetic anhydride. After being kept at 300°C for 30 minutes, the contents were taken out of the reactor and cooled to room temperature. The obtained solid was crushed with a grinder to obtain a powdered liquid crystal polyester (B1). The flow starting temperature of the liquid crystal polyester (B1) was 193.3°C.

The liquid crystal polyester (B1) obtained above was heated from room temperature to 160°C in 2 hours and 20 minutes under a nitrogen environment, and then heated from 160°C to 180°C in 3 hours and 20 minutes, and kept at 180°C for 5 hours to perform solid phase polymerization, and then cooled and pulverized by a pulverizer to obtain a powdered liquid crystal polyester (B2). The flow starting temperature of the liquid crystal polyester (B2) is 220°C.

The liquid crystal polyester (B2) obtained above was heated from room temperature to 180°C in a nitrogen environment for 1 hour and 25 minutes, and then heated from 180°C to 255°C for 6 hours and 40 minutes, and kept at 255°C for 5 hours to perform solid phase polymerization, and then cooled to obtain a powdered liquid crystal polyester (B). The flow starting temperature of the liquid crystal polyester (B) is 302°C. The melting point of the liquid crystal polyester (B) measured using a differential scanning calorimeter was 311°C.

‧Preparation of liquid crystal polyester solution

8 parts by mass of liquid crystal polyester (B) was added to 92 parts by mass of N-methylpyrrolidone (boiling point (1 atmosphere) 204°C), and stirred at 140°C for 4 hours in a nitrogen environment to prepare a liquid crystal polyester solution. The viscosity of the liquid crystal polyester solution was 955 mPa‧s.

‧Manufacturing of liquid crystal polyester film

Using a thin film applicator with a micrometer (SHEEN's "SA204") and an automatic coating device (TESTER Industries, Ltd.'s "Type I"), the liquid crystal polyester solution was cast on the roughened surface of a copper foil (Mitsui Metal Mining Co., Ltd. 3EC-VLP 18μm) to a thickness of 300μm, and then dried at 40°C and normal pressure (1 atmosphere) for 4 hours to remove the solvent from the cast film. The second casting was then performed on the surface of the dried liquid crystal polyester (B) to a thickness of 300μm, and then dried at 40°C and normal pressure (1 atmosphere) for 4 hours to remove the solvent from the cast film.

After the above drying, the temperature was raised from room temperature to 270°C at 1°C/min in a hot air oven under a nitrogen environment and maintained at this temperature for 2 hours for heat treatment to obtain the liquid crystal polyester film with copper foil of Comparative Example 3.

[Comparison Example 4]

・Manufacturing of Liquid Crystal Polyester (C)

The powder of the liquid crystal polyester (A) obtained in Example 1 was filled on a SUS plate and heat treated at 280°C for 6 hours to obtain a liquid crystal polyester (C). The flow initiation temperature of the obtained liquid crystal polyester (C) was 306°C.

・Manufacturing of liquid crystal polyester film 100 parts by weight of the obtained liquid crystal polyester (C) was granulated at 325°C using a double-screw extruder ("PCM-30" manufactured by Ikegai Iron Works Co., Ltd.) to obtain granules. The melting point of the granules was measured using a differential scanning calorimeter and found to be 319°C.

The obtained pellets were melt extruded by a single-axis extruder and then blown into film using an annular blow molding die with a die diameter of 30 mm and a slit interval of 0.25 mm. At this time, a filter device (blade type filter, manufactured by Nippon Seisen Co., Ltd.) connected to the inlet of the annular blow molding die was used to filter the dissolved liquid crystal polyester while forming the film. The filter device was a stack of 16 NASLON filter sheets LF4-0 NF2M-05D2 (manufactured by Nippon Seisen Co., Ltd., filtration accuracy 5.0 μm, blade type) used.

The liquid crystal polyester film of Comparative Example 4 was extruded from an annular blow molding die heated to 340°C under the condition that the stretching ratio in TD was 4.3 relative to the stretching ratio in MD.

The liquid crystal polyester film with copper foil obtained in Examples 1-1 to 1-5 and Comparative Examples 3 to 4 was immersed in an aqueous solution of ferric chloride, and the copper foil was etched away to obtain a single-layer film.

Table 2 shows the above items and their measurement results.

The liquid crystal polyester films of Examples 1-1 to 1-5 are obtained by casting a dispersion of liquid crystal polyester microparticle powder on a copper foil and then performing a heat treatment (abbreviated as "dispersion casting" in the table), so they have excellent dielectric properties and low molecular orientation (MOR). The liquid crystal polyester film of Comparative Example 3 is obtained by casting a solution of liquid crystal polyester microparticle powder on a copper foil (abbreviated as "solution casting" in the table), so it is non-oriented. However, the solution casting method is limited to using liquid crystal polyester that can be dissolved in a solvent as a raw material, so it tends to have poor dielectric properties. Since the liquid crystal polyester film of Comparative Example 4 is obtained by the blow molding method, it tends to have a high molecular orientation (MOR), resulting in poor linear expansion in MD and TD.

The configurations and combinations of the embodiments are examples, and additions, omissions, substitutions, and other changes to the configurations may be made without departing from the gist of the invention. The invention is not limited to the embodiments but only to the scope of the patent application (claim).

1: Liquid crystal polyester powder 3: Medium 30: Liquid crystal polyester composition 10: Liquid crystal polyester film 11: Film 12: Support 13: Metal layer 20,21: Laminated body 22: Laminated body precursor 40: Liquid crystal polyester film precursor

[FIG. 1] is a schematic diagram showing the manufacturing process of a liquid crystal polyester film and a laminate according to an embodiment of the present invention. [FIG. 2] is a schematic diagram showing the film structure according to an embodiment of the present invention. [FIG. 3] is a schematic diagram showing the laminate structure according to an embodiment of the present invention.

1: Liquid crystal polyester powder

3: Media

10: Liquid crystal polyester film

12: Support body

20: Layered body

22: Laminated precursors

30: Liquid crystal polyester composition

40: Liquid crystal polyester film precursor

Claims (7)

A liquid crystal polyester composition, comprising a medium and a liquid crystal polyester powder; the liquid crystal polyester powder comprises a liquid crystal polyester with a number average molecular weight of less than 10,000 and an average particle size of 0.5 to 20 μm; the medium comprises an aprotic compound; the proportion of the aprotic compound in the entire medium is 50 to 100% by mass; the liquid crystal polyester powder is insoluble in the medium. The liquid crystal polyester composition of claim 1, wherein the relative capacitance of the liquid crystal polyester powder at a frequency of 1 GHz is less than 3, and the dielectric tangent at a frequency of 1 GHz is less than 0.005. A liquid crystal polyester composition as claimed in claim 1 or 2, wherein the liquid crystal polyester has a structural unit containing a naphthalene structure. The liquid crystal polyester composition of claim 3, wherein the content of the structural units containing the naphthalene structure is 40 mol% or more relative to the total amount of all structural units in the liquid crystal polyester (100 mol%). The liquid crystal polyester composition of claim 3, wherein 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): (1) -O-Ar ¹ -CO- (2) -CO-Ar ² -CO- (3) -O-Ar ³ -O- (Ar ¹ represents 2,6-naphthalenediyl, 1,4-phenylene or 4,4'-biphenylene, Ar ² and Ar ³ independently represent 2,6-naphthalenediyl, 2,7-naphthalenediyl, 1,4-phenylene, 1,3-phenylene or 4,4'-biphenylene, and the hydrogen atom of Ar ¹ , Ar ² or Ar ³ represents the aforementioned groups may be independently substituted by a halogen atom, an alkyl group having 1 to 10 carbon atoms or an aryl group having 6 to 20 carbon atoms). A method for manufacturing a liquid crystal polyester film, comprising coating a liquid crystal polyester composition as claimed in claim 1 or 2 on a support, and performing heat treatment to obtain a liquid crystal polyester film containing liquid crystal polyester. A method for manufacturing a laminate, comprising coating a liquid crystal polyester composition as claimed in claim 1 or 2 on a support, performing heat treatment to form a liquid crystal polyester film containing liquid crystal polyester, and obtaining a laminate having the support and the liquid crystal polyester film.

Images