JP6619487B1 - Liquid crystal polyester film, liquid crystal polyester liquid composition, and method for producing liquid crystal polyester film - Google Patents

Abstract

A liquid crystal polyester film having a low coefficient of linear expansion and high mechanical strength. A liquid crystal polyester film including at least a liquid crystal polyester, the liquid crystal polyester film having at least a first direction relative to a first direction parallel to a main surface of the liquid crystal polyester film and a first degree of orientation of the liquid crystal polyester. The ratio of the second degree of orientation of the liquid crystal polyester to the second direction perpendicular to the second direction is 0.95 to 1.04, and is measured in a direction parallel to the main surface 2 by a wide-angle X-ray scattering method. The liquid crystal polyester film 1 wherein the third degree of orientation of the liquid crystal polyester is 60.0% or more. [Selection diagram] Fig. 1

Description

  The present invention relates to a liquid crystal polyester film, a liquid crystal polyester liquid composition, and a method for producing a liquid crystal polyester film.

  The liquid crystal polyester film has attracted attention as an electronic substrate material because it has excellent high-frequency characteristics and low water absorption. As a method for producing a liquid crystal polyester film, a melt molding method and a solution casting method are known.

  The melt molding method is a method of forming a kneaded product into a film by extruding it from an extruder. The film formed by the melt molding method has a molecular chain in the extrusion direction (MD, Machine Direction) rather than in the transverse direction to the extrusion direction (direction perpendicular to the extrusion direction and the film thickness direction, TD, Transverse Direction). Easy to align. In particular, in the case of a liquid crystal polyester film, the liquid crystal polyester molecules are easily oriented in MD as compared with other resins. Therefore, the liquid crystal polyester film has a difference in physical properties between MD and TD. For example, a liquid crystal polyester film manufactured by a melt molding method has a large difference in mechanical strength between TD and MD.

  On the other hand, according to the solution casting method, a liquid crystal polyester film can be obtained by casting a liquid composition containing liquid crystal polyester on a support and then removing the solvent contained in the liquid composition. For example, Patent Document 1 discloses a method for producing a liquid crystal polyester film using a liquid crystal polyester liquid composition containing liquid crystal polyester and an aprotic solvent. Patent Document 2 discloses a method for producing a liquid crystal polyester film in which a liquid crystal polyester liquid composition containing liquid crystal polyester and an aprotic solvent is used, and heat treatment is performed at 350 ° C. or more and 400 ° C. or less after removing the solvent. The liquid crystal polyester film produced by the solution casting method is isotropic because the liquid crystal polyester does not align in one direction.

Japanese Patent No. 4470390 Japanese Patent No. 4543851

  According to the method described in Patent Document 1, it is possible to produce an isotropic liquid crystal polyester film, but the coefficient of linear expansion tends to be higher than that of a liquid crystal polyester film produced by a melt molding method. is there. On the other hand, in the method described in Patent Document 2, the linear expansion coefficient of the liquid crystal polyester film is reduced by performing a heat treatment at 350 ° C. or more and 400 ° C. or less after removing the solvent. There is a need for improvement.

  The present invention has been made in view of the above circumstances, and a liquid crystal polyester film having a low coefficient of linear expansion and a high mechanical strength, a liquid crystal polyester liquid composition capable of producing this liquid crystal polyester film, and a liquid crystal polyester film It is an object to provide a manufacturing method.

The present invention includes the following aspects.
[1] A liquid crystal polyester film containing at least liquid crystal polyester, wherein the first orientation degree is an orientation degree with respect to a first direction parallel to the main surface of the liquid crystal polyester film, and a second orientation degree is the main orientation degree. The first orientation degree / the ratio of the first orientation degree and the second orientation degree when the orientation degree is a parallel direction to the second direction perpendicular to the first direction. The second orientation degree is 0.95 or more and 1.04 or less, and the third orientation degree of the liquid crystal polyester measured by the wide angle X-ray scattering method in the direction parallel to the main surface is 60.0% or more. There is a liquid crystal polyester film.
[2] The liquid crystal polyester film according to [1], wherein the third degree of orientation is 60.0% or more and 80.0% or less.
[3] The total of repeating units represented by the formulas (1), (2) and (3), wherein the liquid crystalline polyester includes the repeating units represented by the formulas (1), (2) and (3). The content of the repeating unit represented by the formula (1) with respect to the amount is 30 mol% or more and 80 mol% or less, and the total of the repeating units represented by the formulas (1), (2) and (3) The content of the repeating unit represented by the formula (2) with respect to the amount is 10 mol% or more and 35 mol% or less, and the total of the repeating units represented by the formulas (1), (2) and (3) The liquid crystal polyester film according to [1] or [2], wherein the content of the repeating unit represented by the formula (3) with respect to the amount is 10 mol% or more and 35 mol% or less.
(1) —O—Ar ¹ —CO—
(2) —CO—Ar ² —CO—
⁽³⁾ -X-Ar 3 -Y-
(In the formulas (1) to (3), Ar ¹ represents a phenylene group, a naphthylene group or a biphenylylene group, and Ar ² and Ar ³ are each independently a phenylene group, a naphthylene group, a biphenylene group or the following formula (4): X and Y each independently represents an oxygen atom or an imino group, and each hydrogen atom in the group represented by Ar ¹ , Ar ² and Ar ³ is independently a halogen atom. (It may be substituted with an atom, an alkyl group or an aryl group.)
(4) -Ar ⁴ -Z-Ar ^5-
(In Formula (4), Ar ⁴ and Ar ⁵ each independently represent a phenylene group or a naphthylene group. Z represents an oxygen atom, a sulfur atom, a carbonyl group, a sulfonyl group, or an alkylidene group.)
[4] A liquid crystal polyester liquid composition comprising a liquid crystal polyester and a solvent, wherein the liquid crystal polyester contains repeating units represented by the formulas (1), (2) and (3), and the formula (1) ), The content of the repeating unit represented by the formula (1) with respect to the total amount of the repeating units represented by (2) and (3) is 30 mol% or more and 80 mol% or less, and the formula (1) ), (2) and the content of the repeating unit represented by the formula (2) with respect to the total amount of the repeating units represented by the formula (3) is 10 mol% or more and 35 mol% or less, and the formula (1) ), The content of the repeating unit represented by the formula (3) with respect to the total amount of the repeating units represented by (2) and (3) is 10 mol% or more and 35 mol% or less, and the liquid crystalline polyester liquid The viscosity at 23 ° C. of the composition is 100 mPa · s or more and 100 The liquid crystal polyester liquid composition has a temperature A [° C.] and a retention time B [hr] after reaching the temperature A [° C.] of the mixture containing the liquid crystal polyester and the solvent. A liquid crystal polyester liquid composition obtained by heating and stirring under conditions satisfying (5), (6) and (7).
(1) —O—Ar ¹ —CO—
(2) —CO—Ar ² —CO—
⁽³⁾ -X-Ar 3 -Y-
(In the formulas (1) to (3), Ar ¹ represents a phenylene group, a naphthylene group or a biphenylylene group, and Ar ² and Ar ³ are each independently a phenylene group, a naphthylene group, a biphenylylene group or the following formula (4): X and Y each independently represents an oxygen atom or an imino group, and each hydrogen atom in the group represented by Ar ¹ , Ar ² and Ar ³ is independently a halogen atom. (It may be substituted with an atom, an alkyl group or an aryl group.)
(4) -Ar ⁴ -Z-Ar ^5-
(In Formula (4), Ar ⁴ and Ar ⁵ each independently represent a phenylene group or a naphthylene group. Z represents an oxygen atom, a sulfur atom, a carbonyl group, a sulfonyl group, or an alkylidene group.)
(5) 120 ≦ A <200
(6) 3 ≦ B
(7) 19 ≦ (0.1A + B) <30
[5] The liquid crystalline polyester liquid composition according to [4], further obtained by heating and stirring under conditions satisfying the formula (8).
(8) 130 ≦ A <180
[6] The liquid crystalline polyester liquid composition described in [4] or [5] is cast on a support to form a coating film, the solvent is removed from the coating film, and the solvent is removed. The manufacturing method of the liquid-crystal polyester film which heats the said coating film and isolate | separates the said heated coating film and the said support body.

  ADVANTAGE OF THE INVENTION According to this invention, the liquid crystal polyester film which has a low linear expansion coefficient and high mechanical strength, the liquid crystal polyester liquid composition which can manufacture this liquid crystal polyester film, and the manufacturing method of a liquid crystal polyester film can be provided. .

It is a model perspective view of the liquid-crystal polyester film in one Embodiment of this invention.

  The liquid crystal polyester film in one embodiment of the present invention is a liquid crystal polyester film containing at least a liquid crystal polyester, wherein the first orientation degree is an orientation degree with respect to a first direction parallel to the principal surface of the liquid crystal polyester film, When the degree of orientation of 2 is the degree of orientation with respect to a second direction that is parallel to the main surface and orthogonal to the first direction, the ratio between the first degree of orientation and the second degree of orientation. The first orientation degree / second orientation degree is 0.95 or more and 1.04 or less, and the third orientation of the liquid crystal polyester is measured by a wide angle X-ray scattering method in a direction parallel to the main surface. The degree is 60.0% or more.

  FIG. 1 is a schematic perspective view of a liquid crystal polyester film in the present embodiment. In FIG. 1, the first direction x is parallel to the main surface 2 of the liquid crystal polyester film 1. The second direction y is perpendicular to the first direction x and is parallel to the main surface 2 of the liquid crystal polyester film 1. The third direction z is perpendicular to the first direction x and the second direction y.

  In the present specification, the orientation degree of the liquid crystal polyester with respect to the first direction x is defined as the first orientation degree. Similarly, the orientation degree of the liquid crystal polyester with respect to the second direction is defined as the second orientation degree. The degree of orientation of the liquid crystal polyester with respect to the xy plane, that is, the main surface 2 is defined as a third degree of orientation. A method for measuring the first to third orientation degrees will be described later.

Such a liquid crystal polyester film can be manufactured using the liquid crystal polyester liquid composition in one embodiment of the present invention. The liquid crystal polyester liquid composition according to one embodiment of the present invention is a liquid crystal polyester liquid composition containing a liquid crystal polyester and a solvent, and the liquid crystal polyester is represented by formulas (1), (2), and (3). The content of the repeating unit represented by the formula (1) with respect to the total amount of the repeating units represented by the formulas (1), (2) and (3) is 30 mol% or more and 80 The content of the repeating unit represented by the formula (2) with respect to the total amount of the repeating units represented by the formulas (1), (2) and (3) is 10 mol% or more and 35% or less. The content of the repeating unit represented by the formula (3) with respect to the total amount of the repeating units represented by the formulas (1), (2) and (3) is 10 mol% or more and 35% or less. The liquid crystal polyester liquid composition is not more than mol%. The viscosity at 23 ° C. is 100 mPa · s or more and 1000 mPa · s or less, and the liquid crystal polyester liquid composition is obtained by mixing a mixture containing the liquid crystal polyester and the solvent after reaching the temperature A [° C.] and the temperature A [° C.]. The retention time B [hr] is obtained by heating and stirring under conditions satisfying the formulas (5), (6) and (7).
(1) —O—Ar ¹ —CO—
(2) —CO—Ar ² —CO—
⁽³⁾ -X-Ar 3 -Y-
(In the formulas (1) to (3), Ar ¹ represents a phenylene group, a naphthylene group or a biphenylylene group, and Ar ² and Ar ³ are each independently a phenylene group, a naphthylene group, a biphenylylene group or the following formula (4): X and Y each independently represents an oxygen atom or an imino group, and each hydrogen atom in the group represented by Ar ¹ , Ar ² and Ar ³ is independently a halogen atom. (It may be substituted with an atom, an alkyl group or an aryl group.)
(4) -Ar ⁴ -Z-Ar ^5-
(In Formula (4), Ar ⁴ and Ar ⁵ each independently represent a phenylene group or a naphthylene group. Z represents an oxygen atom, a sulfur atom, a carbonyl group, a sulfonyl group, or an alkylidene group.)
(5) 120 ≦ A <200
(6) 3 ≦ B
(7) 19 ≦ (0.1A + B) <30

  In this specification, the temperature A may be referred to as a dissolution temperature, and the retention time B may be referred to as a dissolution retention time.

The method for producing a liquid crystal polyester film includes casting the liquid crystal polyester liquid composition on a support to form a coating film, removing the solvent from the coating film, and heating the coating film from which the solvent has been removed. And separating the heated coating film and the support.
Hereinafter, one embodiment of the present invention will be described in order.

(Liquid crystal polyester)
The liquid crystalline polyester is a liquid crystalline polyester that exhibits liquid crystallinity in a molten state, and is preferably melted at a temperature of 450 ° C. or lower. The liquid crystal polyester may be a liquid crystal polyester amide, a liquid crystal polyester ether, a liquid crystal polyester carbonate, or a liquid crystal polyester imide. The liquid crystal polyester is preferably a wholly aromatic liquid crystal polyester using only an aromatic compound as a raw material monomer.

The following are mentioned as a typical example of liquid crystalline polyester.
1) (i) an aromatic hydroxycarboxylic acid, (ii) an aromatic dicarboxylic acid, and (iii) at least one compound selected from the group consisting of an aromatic diol, an aromatic hydroxyamine, and an aromatic diamine. Polymerized (polycondensed).
2) A product obtained by polymerizing plural kinds of aromatic hydroxycarboxylic acids.
3) A polymer obtained by polymerizing (i) an aromatic dicarboxylic acid and (ii) at least one compound selected from the group consisting of aromatic diols, aromatic hydroxyamines and aromatic diamines.
4) A polymer obtained by polymerizing (i) a polyester such as polyethylene terephthalate and (ii) an aromatic hydroxycarboxylic acid.
Here, the aromatic hydroxycarboxylic acid, the aromatic dicarboxylic acid, the aromatic diol, the aromatic hydroxyamine, and the aromatic diamine are each independently replaced with a part or all of the polymerizable derivative. Also good.

  Examples of polymerizable derivatives of a compound having a carboxy group such as an aromatic hydroxycarboxylic acid and an aromatic dicarboxylic acid include those obtained by converting a carboxy group into an alkoxycarbonyl group or an aryloxycarbonyl group (ester), carboxy Examples include those obtained by converting a group into a haloformyl group (acid halide), and those obtained by converting a carboxy group into an acyloxycarbonyl group (acid anhydride). Examples of polymerizable derivatives of compounds having a hydroxy group such as aromatic hydroxycarboxylic acids, aromatic diols and aromatic hydroxyamines are those obtained by acylating a hydroxy group and converting it to an acyloxy group (acylated product) Is mentioned. Examples of polymerizable derivatives of amino group-containing compounds such as aromatic hydroxyamines and aromatic diamines include those obtained by acylating an amino group and converting it to an acylamino group (acylated product).

  The liquid crystalline polyester preferably has a repeating unit represented by the following formula (1) (hereinafter sometimes referred to as “repeating unit (1)”), and the repeating unit (1) and the following formula (2) A repeating unit represented (hereinafter sometimes referred to as “repeating unit (2)”) and a repeating unit represented by the following formula (3) (hereinafter sometimes referred to as “repeating unit (3)”). It is more preferable to have.

(1) —O—Ar ¹ —CO—
(2) —CO—Ar ² —CO—
⁽³⁾ -X-Ar 3 -Y-

(Ar ¹ represents a phenylene group, a naphthylene group, or a biphenylylene group. Ar ² and Ar ³ each independently represent a phenylene group, a naphthylene group, a biphenylylene group, or a group represented by the following formula (4). X And Y each independently represents an oxygen atom or an imino group (—NH—), and the hydrogen atoms in the groups represented by Ar ¹ , Ar ² and Ar ³ each independently represent a halogen atom or an alkyl group. Alternatively, it may be substituted with an aryl group.)

(4) -Ar ⁴ -Z-Ar ^5-

(Ar ⁴ and Ar ⁵ each independently represent a phenylene group or a naphthylene group. Z represents an oxygen atom, a sulfur atom, a carbonyl group, a sulfonyl group, or an alkylidene group.)

As said halogen atom, a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom are mentioned. Examples of the alkyl group include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, s-butyl group, t-butyl group, n-hexyl group, 2-ethylhexyl group, An n-octyl group and n-decyl group are mentioned, The carbon number is 1-10 normally. Examples of the aryl group include a phenyl group, an o-tolyl group, an m-tolyl group, a p-tolyl group, a 1-naphthyl group, and a 2-naphthyl group, and the number of carbon atoms is usually 6 to 20. . When the hydrogen atom is substituted with these groups, the number is usually 2 or less for each group represented by Ar ¹ , Ar ² or Ar ³ , and preferably 1 It is as follows.

  Examples of the alkylidene group include a methylene group, an ethylidene group, an isopropylidene group, an n-butylidene group, and a 2-ethylhexylidene group, and the number of carbon atoms is usually 1 to 10.

The repeating unit (1) is a repeating unit derived from a predetermined aromatic hydroxycarboxylic acid. As the repeating unit (1), Ar ¹ is a p-phenylene group (a repeating unit derived from p-hydroxybenzoic acid), and Ar ¹ is a 2,6-naphthylene group (6-hydroxy-2). A repeating unit derived from naphthoic acid) or a 4,4′-biphenylylene group (repeating unit derived from 4′-hydroxy-4-biphenylcarboxylic acid) is preferred.

The repeating unit (2) is a repeating unit derived from a predetermined aromatic dicarboxylic acid. As the repeating unit (2), Ar ² is a p-phenylene group (a repeating unit derived from terephthalic acid), Ar ² is an m-phenylene group (a repeating unit derived from isophthalic acid), Ar ² Is a 2,6-naphthylene group (repeating unit derived from 2,6-naphthalenedicarboxylic acid), and Ar ² is a diphenyl ether-4,4′-diyl group (diphenyl ether- 4,4′-dicarboxylic acid-derived repeating units) are preferred.

The repeating unit (3) is a repeating unit derived from a predetermined aromatic diol, aromatic hydroxylamine or aromatic diamine. As the repeating unit (3), Ar ³ is a p-phenylene group (repeating unit derived from hydroquinone, p-aminophenol or p-phenylenediamine), and Ar ³ is an m-phenylene group (isophthalic acid). And a group in which Ar ³ is a 4,4′-biphenylylene group (derived from 4,4′-dihydroxybiphenyl, 4-amino-4′-hydroxybiphenyl, or 4,4′-diaminobiphenyl). Repeating units) are preferred.

  The content of the repeating unit (1) is the total amount of all repeating units (the mass equivalent amount of each repeating unit (moles by dividing the mass of each repeating unit constituting the liquid crystal polyester by the formula amount of each repeating unit). ) And the total value thereof) is usually 30 mol% or more, preferably 30 to 80 mol%, more preferably 30 to 60 mol%, still more preferably 30 to 40 mol%. The content of the repeating unit (2) is usually 35 mol% or less, preferably 10 to 35 mol%, more preferably 20 to 35 mol%, still more preferably 30 to 35 mol, based on the total amount of all repeating units. %. The content of the repeating unit (3) is usually 35 mol% or less, preferably 10 to 35 mol%, more preferably 20 to 35 mol%, still more preferably 30 to 35 mol, based on the total amount of all repeating units. %. As the content of the repeating unit (1) is increased, the heat resistance, strength and rigidity are likely to be improved. However, when the content is too large, the solubility in a solvent is likely to be lowered.

  The ratio between the content of the repeating unit (2) and the content of the repeating unit (3) is expressed as [content of repeating unit (2)] / [content of repeating unit (3)] (mol / mol). The ratio is usually 0.9 / 1 to 1 / 0.9, preferably 0.95 / 1 to 1 / 0.95, and more preferably 0.98 / 1 to 1 / 0.98.

  In addition, liquid crystalline polyester may have 2 or more types of repeating units (1)-(3) each independently. Further, the liquid crystalline polyester may have a repeating unit other than the repeating units (1) to (3), but the content thereof is usually 10 mol% or less with respect to the total amount of all repeating units, preferably 5 mol% or less.

  The liquid crystalline polyester has a repeating unit (3) in which X and / or Y is an imino group, that is, a repeating unit derived from a predetermined aromatic hydroxylamine and / or a repeating unit derived from an aromatic diamine. It is preferable that it has a solubility in a solvent, and it is more preferable that the repeating unit (3) has only those in which X and / or Y is an imino group.

  The liquid crystalline polyester is preferably produced by melt polymerization of raw material monomers corresponding to the repeating units constituting the liquid crystalline polyester. The melt polymerization may be carried out in the presence of a catalyst. Examples of the catalyst include magnesium acetate, stannous acetate, tetrabutyl titanate, lead acetate, sodium acetate, potassium acetate, and metal compounds such as antimony trioxide. And nitrogen-containing heterocyclic compounds such as 4- (dimethylamino) pyridine and 1-methylimidazole, and nitrogen-containing heterocyclic compounds are preferably used. Note that the melt polymerization may be further solid-phase polymerized as necessary.

  The liquid crystal polyester that can be used as a raw material in the present embodiment has a flow initiation temperature of preferably 250 ° C. or higher, more preferably 250 ° C. or higher and 350 ° C. or lower, and further preferably 260 ° C. or higher and 330 ° C. or lower. The higher the flow start temperature of the liquid crystalline polyester, the easier it is to improve the heat resistance, strength and rigidity. However, if it is too high, the solubility in the solvent tends to be low, and the viscosity of the solution tends to increase.

The flow start temperature is also called flow temperature or flow temperature, and melts the liquid crystalline polyester using a capillary rheometer while increasing the temperature at a rate of 4 ° C./min under a load of 9.8 MPa (100 kg / cm ² ). And a temperature indicating a viscosity of 4800 Pa · s (48000 poise) when extruded from a nozzle having an inner diameter of 1 mm and a length of 10 mm, which is a measure of the molecular weight of the liquid crystalline polyester (“Naked Liquids”, “Liquid Crystal Polymer” -See "Synthesis / Molding / Application-", CMC Corporation, June 5, 1987, p. 95).

  Moreover, it is preferable that the weight average molecular weight is 13000 or less, as for the liquid crystalline polyester used for a raw material by this invention obtained in this way, it is more preferable that it is 3000-13000, it is further more preferable that it is 5000-12000, 5000- It is especially preferable that it is 10,000. The smaller the weight average molecular weight of this liquid crystalline polyester, the better the thermal conductivity in the thickness direction of the film after heat treatment, but if it is too small, the heat resistance, strength and rigidity of the film will be insufficient even after heat treatment. Easy to be.

  The weight average molecular weight can be measured by gel permeation chromatography (GPC).

(solvent)
A liquid composition is obtained by dissolving or dispersing the above-mentioned liquid crystalline polyester in a solvent, preferably by dissolving in a solvent. As the solvent, a liquid crystal polyester to be used is soluble or dispersible, preferably soluble, specifically at a concentration of 1% by mass or more at 50 ° C. ([liquid crystal polyester] / [liquid crystal polyester + solvent]). Those that can be dissolved are appropriately selected and used.

  Examples of the solvent include halogenated hydrocarbons such as dichloromethane, chloroform, 1,1-dichloroethane, 1,2-dichloroethane, 1,1,2,2-tetrachloroethane, 1-chlorobutane, chlorobenzene, o-dichlorobenzene; Halogenated phenols such as p-chlorophenol, pentachlorophenol and pentafluorophenol; ethers such as diethyl ether, tetrahydrofuran and 1,4-dioxane; ketones such as acetone and cyclohexanone; esters such as ethyl acetate and γ-butyrolactone; ethylene Carbonates such as carbonate and propylene carbonate; amines such as triethylamine; nitrogen-containing heterocyclic aromatic compounds such as pyridine; nitriles such as acetonitrile and succinonitrile; N, N-dimethylformamide; -Amides such as dimethylacetamide and N-methylpyrrolidone; Urea compounds such as tetramethylurea; Nitro compounds such as nitromethane and nitrobenzene; Sulfur compounds such as dimethylsulfoxide and sulfolane; and Hexamethylphosphoric acid amide, Tri n-butylphosphoric acid And two or more of them may be used.

  As the solvent, since it is low in corrosivity and easy to handle, an aprotic compound, particularly a solvent mainly composed of an aprotic compound having no halogen atom is preferred, and the proportion of the aprotic compound in the entire solvent is: Preferably it is 50-100 mass%, More preferably, it is 70-100 mass%, More preferably, it is 90-100 mass%. In addition, as the aprotic compound, since liquid crystalline polyester is easily dissolved, amides such as N, N-dimethylformamide, N, N-dimethylacetamide, tetramethylurea, N-methylpyrrolidone, and γ-butyrolactone are used. It is preferable to use an ester, and N, N-dimethylformamide, N, N-dimethylacetamide, and N-methylpyrrolidone are more preferable.

  Moreover, as a solvent, since it is easy to melt | dissolve liquid crystalline polyester, the solvent which has a compound whose dipole moment is 3-5 as a main component is preferable, and the ratio of the compound whose dipole moment which occupies for the whole solvent is 3-5 Is preferably 50 to 100% by mass, more preferably 70 to 100% by mass, and still more preferably 90 to 100% by mass, and a compound having a dipole moment of 3 to 5 is used as the aprotic compound. Is preferred.

  Moreover, as a solvent, since it is easy to remove, the solvent which has as a main component the compound whose boiling point in 1 atmosphere is 220 degrees C or less is preferable, and the ratio of the compound whose boiling point in 1 atmosphere in the whole solvent is 220 degrees C or less Is preferably 50 to 100% by mass, more preferably 70 to 100% by mass, and still more preferably 90 to 100% by mass, and a compound having a boiling point of 220 ° C. or less at 1 atm is used as the aprotic compound. It is preferable.

(Liquid crystal polyester liquid composition)
The liquid crystal polyester liquid composition according to one embodiment of the present invention is a liquid crystal polyester liquid composition containing a liquid crystal polyester and a solvent, and the liquid crystal polyester is represented by formulas (1), (2), and (3). The ratio of the repeating unit represented by the formula (1) to the total molar amount of the repeating units represented by the formulas (1), (2) and (3) is 30 mol% or more and 80% or more. The ratio of the repeating unit represented by the formula (2) to the total molar amount of the repeating units represented by the formulas (1), (2) and (3) is 10 mol% or more and 35% or less. The ratio of the repeating unit represented by the formula (3) to the total molar amount of the repeating units represented by the formulas (1), (2) and (3) is 10 mol% or more and 35% or less. The liquid crystal polyester liquid composition is not more than mol%. The viscosity at 23 ° C. is 100 mPa · s or more and 1000 mPa · s or less, and the liquid crystal polyester liquid composition contains a mixture containing the liquid crystal polyester and the solvent at a temperature A [° C.] and a retention time after the temperature A is reached. B [hr] is a liquid crystal polyester liquid composition obtained by heating and stirring under conditions satisfying the formulas (5), (6) and (7).
(1) —O—Ar ¹ —CO—
(2) —CO—Ar ² —CO—
⁽³⁾ -X-Ar 3 -Y-
(In the formulas (1) to (3), Ar ¹ represents a phenylene group, a naphthylene group or a biphenylylene group, and Ar ² and Ar ³ are represented by a phenylene group, a naphthylene group, a biphenylene group or the following formula (4). X and Y each independently represent an oxygen atom or an imino group, and the hydrogen atoms in the groups represented by Ar ¹ , Ar ² and Ar ³ each independently represent a halogen atom or an alkyl group. And may be substituted with a group or an aryl group.)
(4) -Ar ⁴ -Z-Ar ^5-
(In Formula (4), Ar ⁴ and Ar ⁵ each independently represent a phenylene group or a naphthylene group. Z represents an oxygen atom, a sulfur atom, a carbonyl group, a sulfonyl group, or an alkylidene group.)
(5) 120 ≦ A <200
(6) 3 ≦ B
(7) 19 ≦ (0.1A + B) <30

  The ratio of the liquid crystal polyester contained in the liquid crystal polyester liquid composition is usually 5 to 60% by mass, preferably 5 to 50% by mass, and more preferably 5 to 45% by mass with respect to the total amount of the liquid crystal polyester and the solvent. .

  A liquid composition can mix liquid crystal polyester, an organic solvent, and the other component used as needed at once or in an appropriate order. When using a filler as another component, it is preferable to prepare by dissolving liquid crystal polyester in a solvent to obtain a liquid crystal polyester solution, and dispersing the filler in this liquid crystal polyester solution.

The liquid composition includes a liquid crystal polyester, an organic solvent, and a mixture containing other components used as necessary, and the temperature A [° C.] and the retention time B [hr] after reaching the temperature A [° C.] are expressed by the formula (5). ), (6) and (7).
(5) 120 ≦ A <200
(6) 3 ≦ B
(7) 19 ≦ (0.1A + B) <30

The temperature A [° C.] preferably further satisfies the formula (8).
(8) 130 ≦ A <180
The temperature A [° C.] is particularly preferably 130 ≦ A ≦ 170.

  The holding time B [hr] after reaching the temperature A [° C.] is determined so as to satisfy 3 ≦ B and 19 ≦ (0.1A + B) <30.

  A liquid crystal polyester liquid composition having a viscosity at 23 ° C. of 100 mPa · s or more and 1000 mPa · s or less by heating and stirring a mixture containing the liquid crystal polyester liquid composition and a solvent under the conditions satisfying the formulas (5) to (7) Things are obtained.

  The viscosity of the liquid crystal polyester liquid composition is a value measured at 23 ° C. using a B-type viscometer (for example, “TVL-20 type”, rotor No. 21, rotation speed 5 rpm, manufactured by Toki Sangyo Co., Ltd.).

  A liquid crystal polyester film produced using a liquid crystal polyester liquid composition obtained by heating and stirring a mixture containing a liquid crystal polyester and a solvent under conditions satisfying the formulas (5) to (7) has a low linear expansion coefficient and a high Has mechanical strength. Details of the liquid crystal polyester film will be described later.

  The liquid crystal polyester liquid composition may contain one or more other components such as a filler, an additive, and a resin other than the liquid crystal polyester.

  Examples of fillers include inorganic fillers such as silica, alumina, titanium oxide, barium titanate, strontium titanate, aluminum hydroxide, calcium carbonate; and organic fillers such as cured epoxy resins, crosslinked benzoguanamine resins, and crosslinked acrylic resins The material may be mentioned, and the content thereof may be 0, preferably 100 parts by mass or less, with respect to 100 parts by mass of the liquid crystalline polyester.

  Examples of the additive include a leveling agent, an antifoaming agent, an antioxidant, an ultraviolet absorber, a flame retardant, and a colorant, and the content thereof is 0 with respect to 100 parts by mass of the liquid crystalline polyester. Preferably, it is 5 mass parts or less.

  Examples of resins other than liquid crystal polyester include polypropylene, polyamide, polyester other than liquid crystal polyester, polyphenylene sulfide, polyether ketone, polycarbonate, polyether sulfone, polyphenylene ether and modified products thereof, and heat other than liquid crystal polyester such as polyether imide. Examples include plastic resins; 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 is 100 parts by mass of the liquid crystalline polyester. And may be 0, preferably 20 parts by mass or less.

(Production method of liquid crystal polyester film)
The liquid crystal polyester film can be produced using the liquid crystal polyester liquid composition described above. First, a liquid crystal polyester liquid composition is cast on a support. The liquid crystal polyester liquid composition can be cast on a support by a method such as a roller coating method, a dip coating method, a spray coating method, a spinner coating method, a curtain coating method, a slot coating method, and a screen printing method. And a method capable of casting the surface smoothly and uniformly on the support is appropriately selected. The liquid crystal polyester liquid composition may be filtered as necessary before casting to remove foreign substances contained in the liquid composition.

  As a support body, a glass plate, a resin film, or metal foil is mentioned, for example. Among them, a resin film is preferable, and a polyimide (PI) film is particularly preferable because of excellent heat resistance, easy application of a liquid composition, and easy peeling from a liquid crystal polyester film. Examples of commercially available polyimide (PI) films include “U-Pyrex S” and “U-Pyrex R” from Ube Industries, Ltd., “Kapton” from Toray DuPont Co., Ltd., and “ IF30 ”,“ IF70 ”and“ LV300 ”. The thickness of the resin film is usually 25 μm or more and 75 μm or less, preferably 50 μm or more and 75 μm.

  Next, a part of the solvent is removed from the cast film-like liquid crystal polyester liquid composition (coating film) to form a liquid crystal polyester film precursor on the support. A liquid crystal polyester film precursor is a film formed by removing a part of a solvent from a coating film. The ratio of the solvent contained in the liquid crystal polyester film precursor is 3% by mass or more and 12% by mass or less with respect to the total mass of the liquid crystal polyester film precursor. If the solvent content in the liquid crystal polyester film precursor is less than 3% by mass, the thermal conductivity of the liquid crystal polyester film tends to be lowered. On the other hand, when the solvent content in the liquid crystal polyester film precursor exceeds 12% by mass, the appearance of the liquid crystal polyester film is likely to deteriorate due to foaming during heat treatment. The proportion of the solvent contained in the liquid crystal polyester film precursor is preferably 5% by mass or more and 10% by mass or less with respect to the total mass of the liquid crystal polyester film precursor.

  The removal of the solvent is preferably carried out by evaporating the solvent. Examples of the method include heating, decompression and ventilation, and these may be combined. Moreover, the removal of a solvent may be performed by a continuous type and may be performed by a single wafer type. From the viewpoint of productivity and operability, the removal of the solvent is preferably performed by heating in a continuous manner, and more preferably by heating with continuous ventilation. The solvent removal temperature is usually 40 ° C. or higher and 200 ° C. or lower, preferably 60 ° C. or higher and 200 ° C. The time for removing the solvent is appropriately adjusted so that the solvent content in the liquid crystal polyester film precursor is 3 to 12% by mass. The time for removing the solvent is, for example, from 0.2 hours to 12 hours, and preferably from 0.5 hours to 8 hours.

  In order to adjust the thickness of the liquid crystal polyester film precursor, casting may be performed twice or more. In addition, when performing casting twice or more, after casting a liquid-crystal polyester liquid composition on a support body and removing a part of solvent on the said drying conditions, a second casting and drying are implemented. .

  The laminate (hereinafter sometimes referred to as laminate (a)) having the support thus obtained and the liquid crystal polyester film precursor was heated from the boiling point of the solvent from −50 ° C. to 280 ° C. within 5 minutes. Then, it is heat-treated at 230 ° C. or higher and 320 ° C. or lower, and may be referred to as a laminate (hereinafter referred to as laminate (b)) having a support and a liquid crystal polyester film (a film obtained by heat-treating a liquid crystal polyester film precursor). ) The temperature range of the heat treatment is more preferably 250 ° C. or higher and 320 ° C. or lower, and further preferably 270 ° C. or higher and 300 ° C. or lower. In this way, by heating from a predetermined temperature to a predetermined temperature in a short time, and then heat-treating at the predetermined temperature, a liquid crystal polyester molecular chain forms a domain in which liquid crystal is aligned, and the thermal conductivity, particularly the thickness A liquid crystal polyester film having excellent thermal conductivity in the direction and excellent in appearance and bending workability can be obtained. In addition, the boiling point of a solvent here means the boiling point in the pressure at the time of temperature rising. When the heating of the laminate (a) is started from less than −50 ° C. of the boiling point of the solvent, the time from reaching −50 ° C. of the boiling point of the solvent to 230 ° C. should be within 5 minutes. Good. The time until the boiling point of the solvent reaches −50 ° C. is arbitrary. Moreover, what is necessary is just to consider the time after reaching 230 degreeC as heat processing time.

  The heat treatment may be carried out continuously or in a single wafer manner, similar to the removal of the solvent, but is preferably carried out continuously from the viewpoint of productivity and operability, following the removal of the solvent. More preferably, it is carried out continuously.

  The liquid crystal polyester film can be obtained as a single layer film by separating the liquid crystal polyester film from the laminate (b) having the support and the liquid crystal polyester film thus obtained. When the glass plate is used as the support, the separation of the liquid crystal polyester film from the laminate (b) is preferably performed by peeling the liquid crystal polyester film from the laminate (b). When a resin film is used as the support, the resin film or the liquid crystal polyester film is preferably peeled from the laminate (b). When metal foil is used as the support, the metal foil is preferably removed from the laminate (b) by etching away. It is preferable to use a resin film, particularly a polyimide film, as the support because the polyimide film or the liquid crystal polyester film is easily peeled off from the laminate (b) and a liquid crystal polyester film having a good appearance can be obtained. When metal foil is used as the support, the laminate (b) may be used as a metal-clad laminate for printed wiring boards without separating the liquid crystal polyester film from the laminate (b).

(Liquid crystal polyester film)
The liquid crystal polyester in one embodiment of the present invention can be manufactured by the above-described method for manufacturing a liquid crystal polyester film.
The liquid crystal polyester film in one embodiment of the present invention is a liquid crystal polyester film containing at least a liquid crystal polyester, wherein the first orientation degree is an orientation degree with respect to a first direction parallel to the principal surface of the liquid crystal polyester film, When the degree of orientation of 2 is the degree of orientation with respect to a second direction that is parallel to the main surface and orthogonal to the first direction, the ratio between the first degree of orientation and the second degree of orientation. The first orientation degree / second orientation degree is 0.95 or more and 1.04 or less, and the third orientation of the liquid crystal polyester is measured by a wide angle X-ray scattering method in a direction parallel to the main surface. The degree is 60.0% or more.

  As described above, as shown in FIG. 1, in the liquid crystal polyester film 1 in one embodiment of the present invention, the first direction x is parallel to the main surface 2 of the liquid crystal polyester film 1. The second direction y is perpendicular to the first direction x and is parallel to the main surface 2 of the liquid crystal polyester film 1. The third direction z is perpendicular to the first direction x and the second direction y. The first direction may be parallel to the casting direction of the liquid crystal polyester liquid composition when the liquid crystal polyester film 1 is manufactured.

  The first orientation degree and the second orientation degree are measured by a microwave molecular orientation meter (for example, MOA-5012A manufactured by Oji Scientific Instruments). The microwave molecular orientation meter is a device that utilizes the fact that the microwave transmission intensity differs between the orientation direction and the perpendicular direction depending on the orientation of the molecules. Specifically, while rotating the sample, a microwave having a certain frequency (generally 4 GHz or 12 GHz is used) is irradiated, and the intensity of the transmitted microwave that changes depending on the molecular orientation is measured. The interaction between the microwave electric field having a constant frequency and the dipoles constituting the molecule is related to the inner product of both vectors. Since the intensity of the microwave changes depending on the angle at which the sample is arranged due to the anisotropy of the dielectric constant of the sample, it is possible to know the degree of orientation.

  Using the above measurement results, the ratio between the first orientation degree and the second orientation degree, that is, the value of the first orientation degree / the second orientation degree is calculated. The value of the first degree of orientation / second degree of orientation is preferably 0.95 or more and 1.04 or less, and more preferably 0.98 or more and 1.02 or less. If the value of the first orientation degree / second orientation degree is 0.95 or more and 1.04 or less, the difference between the mechanical strength in the first direction and the mechanical strength in the second direction of the liquid crystal polyester film is small. That is, the mechanical strength as a liquid crystal polyester film is high. When the value of the first orientation degree / second orientation degree is larger than 1, it means that the liquid crystal polyester film is oriented in the first direction, that is, the casting direction of the liquid crystal polyester liquid composition.

  The third degree of orientation is measured by a wide angle X-ray scattering method in a direction parallel to the main surface 2 of the liquid crystal polyester film 1. The measurement by the wide angle X-ray scattering method is performed as follows, for example. An imaging plate is installed in an X-ray small angle scattering apparatus (for example, NanoSTAR manufactured by Bruker Akex S, Inc.). X-rays are generated at an output of 50 kV and 100 mA using a rotating anti-cathode X-ray generator of a Cu target, and irradiated to the liquid crystal polyester film so as to be parallel to the main surface 2 of the liquid crystal polyester film 1. X-rays are liquid crystal polyester through an X-ray optical system consisting of a cross-coupled gobel mirror and three pinhole slits (the diameters of the slits are 500 μmφ, 150 μmφ, and 500 μmφ from the X-ray generator side). Irradiate the film. X-rays scattered by the liquid crystal polyester film are detected using an imaging plate (IP). The camera length from the sample to the IP is 15 cm. The degree of vacuum in the X-ray small angle scattering apparatus at the time of measurement is 40 Pa or less.

The molecular chain orientation degree (%) (that is, the third orientation degree) of the liquid crystal polymer is a diffraction peak between Debye obtained by measurement by the wide-angle X-ray scattering method (diffraction peak appearing in the vicinity of diffraction angle 2θ = 19.8 °). ), The peak intensity half-value width x ° (peak width at half the peak height) obtained from the intensity profile from 0 ° to 180 ° in each direction is calculated using the formula (I). The
Third degree of orientation (%) = {(180−x) / 180} × 100 (I)

  In the present embodiment, the third orientation degree of the liquid crystal polyester measured by the wide angle X-ray scattering method in the direction parallel to the main surface 2 is preferably 60.0% or more. The upper limit value of the third degree of orientation is not particularly limited, and is preferably 80.0% and more preferably 75.0%. The upper limit value and lower limit value of the third orientation degree can be arbitrarily combined. For example, the third degree of orientation is preferably 60.0% or more and 80.0% or less, and more preferably 60.0% or more and 75.0% or less. A liquid crystal polyester film having a third degree of orientation of 60.0% or more has a low linear expansion coefficient and a high mechanical strength. When the third orientation degree is 80% or less, the value of the first orientation degree / the second orientation degree and the maximum point stress can be maintained in an appropriate range.

  The 3rd orientation degree in this specification shows the orientation degree measured by a wide-angle X-ray scattering method in the direction parallel to main surface 2 as mentioned above. It shows the ratio of liquid crystal polyester having a predetermined azimuth angle with respect to the z-axis direction with respect to all liquid crystal polyester. The predetermined azimuth angle may be 90 ° (that is, parallel to the xy plane) with respect to the z-axis direction, or may be other than that.

  The linear expansion coefficient of the liquid crystal polyester film having the above first to third orientation degrees is 35 ppm / K or less, preferably 34 ppm / K or less. Although the lower limit of the linear expansion coefficient of a liquid crystal polyester film is not specifically limited, For example, it is 0 ppm / K or more. That is, the linear expansion coefficient of the liquid crystal polyester film is 0 ppm / K or more and 35 ppm / K or less, preferably 5 ppm / K or more and 34 ppm / K or less. That is, the liquid crystal polyester film having the first to third orientation degrees has a low linear expansion coefficient and high dimensional stability.

  The linear expansion coefficient of the liquid crystal polyester film is measured as follows. Using a thermomechanical analyzer (for example, TMA manufactured by Rigaku Corporation), the temperature inside the thermomechanical analyzer is increased at 5 ° C./min under a nitrogen stream, and the linear expansion coefficient of the liquid crystal polyester film at 50 to 100 ° C. Measure.

  The maximum point stress of the liquid crystal polyester film having the above-described first to third orientation degrees is 125 MPa or more, and preferably 130 MPa or more. Although the upper limit of the maximum point stress of a liquid crystal polyester film is not specifically limited, For example, it is 1000 MPa or less. That is, the maximum point stress of the liquid crystal polyester film is 125 MPa or more and 800 MPa or less, and preferably 130 MPa or more and 600 MPa or less. As described above, the liquid crystal polyester film having the first to third orientation degrees has high mechanical strength.

  The maximum point stress of the liquid crystal polyester film is measured as follows. The liquid crystal polyester film was cut into a tensile test No. 3 dumbbell having a parallel part width of 5 mm and a length of 20 mm based on JIS K6251, and in accordance with JIS K7161, a tensile tester (for example, Autograph AG-manufactured by Shimadzu Corporation) It is obtained by conducting a tensile test at a tensile speed of 5 mm / min using IS).

The liquid crystal polyester film is produced using the liquid crystal polyester liquid composition as described above. Therefore, in the liquid crystal polyester film of one embodiment of the present invention, the liquid crystal polyester includes repeating units represented by the formulas (1), (2), and (3), and the formulas (1), (2), and (3) The content of the repeating unit represented by the formula (1) with respect to the total amount of the repeating unit represented by (1) is 30 mol% or more and 80 mol% or less, and the formulas (1), (2) and (3) ) The content of the repeating unit represented by the formula (2) with respect to the total amount of the repeating units represented by the formula (10) is from 10 mol% to 35 mol%, and the formulas (1), (2) and (3) The content of the repeating unit represented by the formula (3) with respect to the total amount of the repeating unit represented by () is 10 mol% or more and 35 mol% or less.
(1) —O—Ar ¹ —CO—
(2) —CO—Ar ² —CO—
⁽³⁾ -X-Ar 3 -Y-
(In the formulas (1) to (3), Ar ¹ represents a phenylene group, a naphthylene group or a biphenylylene group, and Ar ² and Ar ³ are each independently a phenylene group, a naphthylene group, a biphenylene group or the following formula (4): X and Y each independently represents an oxygen atom or an imino group, and the hydrogen atoms in the groups represented by Ar ¹ , Ar ² and Ar ³ are each independently a halogen atom. , May be substituted with an alkyl group or an aryl group.)
(4) -Ar ⁴ -Z-Ar ^5-
(In Formula (4), Ar ⁴ and Ar ⁵ each independently represent a phenylene group or a naphthylene group. Z represents an oxygen atom, a sulfur atom, a carbonyl group, a sulfonyl group, or an alkylidene group.)

  The thickness of the liquid crystal polyester film is usually 5 μm or more and 50 μm or less, preferably 10 μm or more and 50 μm or less. In addition, the thickness of a liquid crystal polyester film is obtained by measuring an arbitrary five places with a high-precision digital length measuring machine (manufactured by Mitutoyo Corporation, VL-50AS) and calculating an average value thereof.

  The liquid crystal polyester film thus obtained has a low linear expansion coefficient, high mechanical strength, and excellent performance such as high frequency characteristics and low water absorption inherent in liquid crystal polyester. It can be suitably used for film applications for electronic parts such as plates.

  EXAMPLES Hereinafter, although this invention is demonstrated more concretely using an Example, this invention is not limited by an Example.

<Evaluation method>
[Measurement of flow start temperature of liquid crystalline polyester]
Using a flow tester (Shimadzu Corporation, CFT-500 type), about 2 g of liquid crystal polyester was filled into a cylinder equipped with a die having a nozzle having an inner diameter of 1 mm and a length of 10 mm, and 9.8 MPa (100 kg / cm ^2). ), The liquid crystal polyester was melted while being heated at a rate of 4 ° C./min, extruded from a nozzle, and a temperature showing a viscosity of 4800 Pa · s (48000 P) was measured.

[Measurement of viscosity of liquid crystal polyester liquid composition]
Using a B-type viscometer (TV-22 manufactured by Toki Sangyo Co., Ltd.), the viscosity of the liquid crystal polyester liquid composition was measured at 23 ° C.

[Measurement of ratio of second orientation degree to first orientation degree of liquid crystal polyester film]
By irradiating microwaves of 12.5 to 12.6 GHz with a microwave molecular orientation meter (MOA-5012A, manufactured by Oji Scientific Instruments Co., Ltd.), the second orientation degree relative to the first orientation degree of the liquid crystal polyester film The ratio of was measured.

[Measurement of third degree of orientation of liquid crystal polyester film]
The wide-angle X-ray diffraction measurement was performed by measuring the second orientation degree of the liquid crystal polyester film using a small-angle X-ray scattering apparatus (Bruker AXS Co., Ltd., NanoSTAR) provided with an imaging plate. X-rays were generated at an output of 50 kV and 100 mA using a rotating anti-cathode X-ray generator with a Cu target, and irradiated to the liquid crystal polyester film so as to be parallel to the main surface of the liquid crystal polyester film. X-rays are liquid crystal via an X-ray optical system consisting of a cross-coupled Gabel mirror and three pinhole slits (the diameters of the slits were 500 μmφ, 150 μmφ, and 500 μmφ from the X-ray generator side). The polyester film was irradiated. X-rays scattered by the liquid crystal polyester film were detected using an imaging plate (IP). The camera length from the sample to the IP was 15 cm. The degree of vacuum in the X-ray small angle scattering apparatus at the time of measurement was 40 Pa or less.

[Measurement of linear expansion coefficient of liquid crystal polyester film]
Using a thermomechanical analyzer (manufactured by Rigaku Denki Co., Ltd., TMA), the temperature inside the thermomechanical analyzer is increased at 5 ° C / min in a nitrogen stream, and the linear expansion coefficient of the liquid crystal polyester film at 50-100 ° C is measured did.

[Maximum stress measurement of liquid crystal polyester film]
The liquid crystal polyester film was cut into a tensile test No. 3 dumbbell having a parallel part width of 5 mm and a length of 20 mm based on JIS K6251, and based on JIS K7161, a tensile tester (for example, Autograph AG-manufactured by Shimadzu Corporation) It was determined by carrying out a tensile test at a tensile speed of 5 mm / min using (IS).

<Manufacture of liquid crystal polyester liquid composition>
[Production of liquid crystalline polyester]
(Production Example 1)
In a reactor equipped with a stirrer, a torque meter, a nitrogen gas inlet tube, a thermometer and a reflux condenser, 940.9 g (5.0 mol) of 6-hydroxy-2-naphthoic acid, 4-hydroxyacetaminophen 377. 9 g (2.5 mol), 415.3 g (2.5 mol) of isophthalic acid and 867.8 g (8.4 mol) of acetic anhydride were added, and the gas in the reactor was replaced with nitrogen gas. Under stirring, the temperature was raised from room temperature to 143 ° C. over 60 minutes and refluxed at 143 ° C. for 1 hour. Next, while distilling off by-product acetic acid and unreacted acetic anhydride, the temperature was raised from 150 ° C. to 300 ° C. over 5 hours and held at 300 ° C. for 30 minutes. Cooled down. The obtained solid was pulverized with a pulverizer to obtain a powdered liquid crystal polyester (1). The liquid crystal polyester (1) had a flow start temperature of 191 ° C.
Liquid crystalline polyester (1) was heated from room temperature to 160 ° C. over 2 hours and 20 minutes in a nitrogen atmosphere, then heated from 160 ° C. to 180 ° C. over 3 hours and 20 minutes, and held at 180 ° C. for 5 hours. Thus, after solid-phase polymerization, it was cooled and then pulverized by a pulverizer to obtain a powdery liquid crystalline polyester (2). The liquid crystal polyester (2) had a flow start temperature of 220 ° C.

  Next, the liquid crystalline polyester (2) was heated from room temperature to 180 ° C. over 1 hour and 20 minutes in a nitrogen atmosphere, then heated from 180 ° C. to 240 ° C. over 5 hours, and then at 240 ° C. for 5 hours. By holding, solid phase polymerization was performed, followed by cooling to obtain a powdery liquid crystal polyester. The liquid crystal polyester had a flow initiation temperature of 285 ° C.

(Production Example 2)
A liquid crystal polyester (2) was obtained in the same manner as in Production Example 1.
Next, the liquid crystal polyester (2) was heated from room temperature to 180 ° C. over 1 hour and 20 minutes in a nitrogen atmosphere, then heated from 180 ° C. to 245 ° C. over 5 hours and 25 minutes, and heated at 245 ° C. for 5 hours. By maintaining for a period of time, solid-state polymerization was performed, and then cooled to obtain a powdery liquid crystal polyester. The liquid crystal polyester had a flow starting temperature of 294 ° C.

(Production Example 3)
A liquid crystal polyester (2) was obtained in the same manner as in Production Example 1.
Next, the liquid crystalline polyester (2) was heated from room temperature to 180 ° C. over 1 hour and 20 minutes in a nitrogen atmosphere, then heated from 180 ° C. to 250 ° C. over 5 hours and 50 minutes, and at 250 ° C. for 5 hours. By maintaining for a period of time, solid-state polymerization was performed, followed by cooling to obtain a powdery liquid crystal polyester. The liquid crystal polyester had a flow start temperature of 303 ° C.

(Production Example 4)
In a reactor equipped with a stirrer, a torque meter, a nitrogen gas inlet tube, a thermometer, and a reflux condenser, 103.499 g (5.5 mol) of 6-hydroxy-2-naphthoic acid and 272.52 g (2.475) of hydroquinone were added. Mole, 0.225 mole excess charge), 37.33 g (1.75 mole) 2,6-naphthalenedicarboxylic acid, 83.07 g (0.5 mole) terephthalic acid, 1226.87 g (12 mole) acetic anhydride, and As a catalyst, 0.17 g of 1-methylimidazole was added and stirred at room temperature for 15 minutes.
Next, while distilling off the by-product acetic acid to be distilled off and unreacted acetic anhydride, the temperature was raised from 145 ° C. to 310 ° C. over 3 hours and 30 minutes and kept at 310 ° C. for 3 hours to obtain a liquid crystal polyester. . The liquid crystal polyester thus obtained was cooled to room temperature and pulverized with a pulverizer to obtain a powdered liquid crystal polyester (prepolymer) having a particle size of about 0.1 to 1 mm.
The prepolymer was heated from 25 ° C. to 250 ° C. over 1 hour, and then heated from 250 ° C. to 310 ° C. over 10 hours. Thereafter, the mixture was kept at 310 ° C. for 5 hours for solid phase polymerization, and further cooled to obtain a powdery liquid crystal polyester. The flow starting temperature of the liquid crystalline polyester was 333 ° C.
Using powdered liquid crystal polyester, granulation is performed at a temperature 10 ° C. higher than the flow start temperature to the flow start temperature of the liquid crystal polyester powder by a twin screw extruder (manufactured by Ikekai Co., Ltd., PCM-30) to obtain pellets It was. When the melt viscosity of the obtained pellet at a measurement temperature of 340 ° C. was measured, it was 101 Pa · s.

[Production of liquid crystal polyester liquid composition]
(Example 1)
The liquid crystal polyester (32 g) obtained in Production Example 1 was added to N-methylpyrrolidone (368 g) and heated with stirring to a dissolution temperature of 140 ° C. After reaching 140 ° C., it was maintained at 140 ° C. for 7 hours. A liquid crystal polyester liquid composition was obtained by heating and stirring.

(Examples 2-6, Comparative Examples 1-6)
The liquid crystal polyester, the dissolution temperature and the dissolution holding time were changed as shown in Tables 1 and 2, and the liquid crystal polyester liquid compositions of Examples 2 to 6 and Comparative Examples 1 to 6 were prepared by the method described in Example 1. Obtained.

[Production of liquid crystal polyester film]
The liquid crystal polyester liquid composition of Example 1 was subjected to a film applicator with a micrometer (manufactured by SHEN Co., SA204) and an automatic coating apparatus on a copper foil (manufactured by Mitsui Metal Mining Co., Ltd., 3EC-VLP (thickness: 18 μm)). After casting using (type I, manufactured by Tester Sangyo Co., Ltd.), the solvent is partially removed from the coating film by drying at 60 ° C. and normal pressure (1 atm) for 4 hours, and then the second time The casting and drying were performed in the same order as the first casting. Thereby, the liquid crystalline polyester film precursor was formed. A heat treatment was performed in a hot air oven under a nitrogen atmosphere from room temperature to 270 ° C. over 4 hours and maintained at 270 ° C. for 2 hours. The copper foil was removed from the resulting laminate of the liquid crystal polyester film and the copper foil by etching using a ferric chloride solution to obtain a single-layer liquid crystal polyester film.

  The liquid crystal polyester liquid composition of Example 1 except that the liquid crystal polyester liquid compositions of Examples 2 to 6 and Comparative Examples 1 to 6 were cast so that the thickness of the liquid crystal polyester film had the values shown in Table 3 or Table 4. A liquid crystal polyester film was produced by the same procedure as the method for producing a liquid crystal polyester film using the composition.

  Measurement of the ratio between the first orientation degree and the second orientation degree of the liquid crystal polyester film using the liquid crystal polyester liquid compositions of Examples 1 to 6 and Comparative Examples 1 to 6, measurement of the third orientation degree, line Tables 3 and 4 show the results of the expansion coefficient measurement and the maximum point stress measurement. In Table 4, “Unmeasurable” indicates that the liquid crystal polyester liquid composition was too low in viscosity to be formed as a film, and each evaluation item could not be measured.

  The evaluation results of the liquid crystal polyester film produced by melt molding are shown in Table 4 as Comparative Example 8. Specifically, the pellet obtained in Production Example 4 is kneaded with a single screw extruder (manufactured by Yamaguchi Seisakusho Co., Ltd.), and an annular inflation die (manufactured by Yamaguchi Seisakusho Co., Ltd.) having a die diameter of 30 mm and a slit interval of 0.25 mm. At the inlet of the filter, a filtration device (manufactured by Nippon Seisen Co., Ltd., leaf disk type filter) is connected, extruded from an annular inflation die heated to 340 ° C., and stretched in a direction perpendicular to the take-up direction with respect to the draw ratio in the take-up direction. A liquid crystal polyester film was obtained under conditions where the magnification was 4.1 times. When the film thickness of the obtained liquid crystal polyester film was measured at a plurality of locations, all were 25 μm. The filtration device used was a stack of 16 NASLON filters LF4-0 NF2M-05D2 (manufactured by Nippon Seisen Co., Ltd., filtration accuracy 5.0 μm, leaf disk type).

  The liquid crystal polyester films using the liquid crystal polyester liquid compositions of Examples 1 to 6 had a maximum point stress in the range of 130 MPa or more and 140 MPa or less, which was larger than those of Comparative Examples 1 to 5. Moreover, the liquid crystal polyester film using the liquid crystal polyester liquid composition of Examples 1-6 has a linear expansion coefficient in the range of 32 ppm / K or more and 34 ppm / K or less, and is a small value compared with Comparative Examples 1-6. became. The liquid crystal polyester film using the liquid crystal polyester liquid composition of Examples 1 to 6 is the third orientation of the liquid crystal polyester film while maintaining the ratio of the first orientation degree and the second orientation degree around 1.00. The degree was 61.9 to 65.0%, which was larger than Comparative Examples 1 to 5 and 8.

  The reason why such a result was obtained in the liquid crystal polyester film using the liquid crystal polyester liquid composition of Examples 1 to 6 was that both the dissolution temperature and the dissolution holding time of the liquid crystal polyester when the liquid crystal polyester liquid composition was produced. It is thought that it was effective to control. Specifically, in the production of the liquid crystal polyester liquid composition, when the mixture containing the liquid crystal polyester and the organic solvent is heated and stirred, the temperature A [° C.] (that is, the dissolution temperature) and the holding time after reaching the temperature A [° C.]. B [hr] (that is, dissolution retention time) satisfies the formulas (5) to (7), and the viscosity at 23 ° C. is set to 100 mPa · s or more and 1000 mPa · s or less.

(5) 120 ≦ A <200
(6) 3 ≦ B
(7) 19 ≦ (0.1A + B) <30

  As shown in Examples 1 to 6, by producing the liquid crystal polyester liquid composition under the conditions satisfying the formulas (5) to (7), the liquid crystal polyester molecules in the liquid crystal polyester liquid composition are entangled and individually The liquid crystal polyester molecules are considered to be easily separated. As a result, it is considered that the third degree of orientation tends to increase in the heat treatment of the liquid crystal polyester film precursor.

  In the liquid crystal polyester liquid composition, when the temperature A is low or the retention time B is short, the formulas (5) to (7) are not satisfied, or the viscosity at 23 ° C. is not 100 mPa · s to 1000 mPa · s. It is considered that the entanglement between the liquid crystal polyester molecules is not sufficiently released, and the third degree of orientation is hardly increased in the heat treatment of the liquid crystal polyester film precursor.

  For example, when Example 4 and Comparative Example 1 are compared, in Example 4, the temperature A is 160 ° C. and the third orientation degree is 61.9%, but in Comparative Example 1, the dissolution retention time B is In spite of being the same as Example 4, since the temperature A is 120 ° C., the third degree of orientation is 58.4%. Further, when Example 2 and Comparative Examples 3 to 5 are compared, in Example 2, the dissolution retention time B is 15 hours and the third degree of orientation is 62.8%. Since the holding time B is 0 to 4 hours, the third orientation degree is 58.8 to 59.2%.

  If the temperature A is high or the holding time B is long and the formulas (5) to (7) cannot be satisfied, the solution viscosity of the liquid crystal polyester liquid composition is too low to be formed as a film. .

  For example, when Example 1 and Comparative Example 7 were compared, in Example 1, the temperature A was 140 ° C., so it could be formed as a film, but in Comparative Example 7, the dissolution retention time was 3 hours. In spite of being shorter than Example 1, since the temperature A was 180 ° C., the solution viscosity was excessively lowered and could not be formed as a film. In addition, when Example 3 and Comparative Example 6 were compared, in Example 3, the dissolution retention time B was 3 hours, so that it could be formed as a film. In Comparative Example 6, the dissolution retention time B was 15 Since it was time, the solution viscosity was too low to be formed as a film.

  The temperature A [° C.] when the mixture containing the liquid crystal polyester and the organic solvent is heated and stirred, and the holding time B [hr] after reaching the temperature A [° C.] satisfy the formulas (5) to (7), and 23 A liquid crystalline polyester film having a low linear expansion coefficient and a high mechanical strength is produced by producing a liquid crystalline polyester film using a liquid crystalline polyester liquid composition produced under a condition that the viscosity at 100 ° C. is 100 mPa · s or more and 1000 mPa · s or less. Can be achieved.

  In addition, the liquid crystal polyester film of Comparative Example 8 manufactured by melt molding is excellent in the maximum point stress and the linear expansion coefficient as in Examples 1 to 6, but the first degree of orientation and the second degree of orientation are The ratio is 2 or more, and anisotropy is strong. Therefore, the mechanical strength in the second direction relative to the mechanical strength in the first direction of the liquid crystal polyester film is small, and the stability of the mechanical strength of the entire liquid crystal polyester film is poor.

1 ... Liquid crystal polyester film, 2 ... Main surface.

Claims (5)

A liquid crystal polyester film containing at least liquid crystal polyester,
The first degree of orientation is the degree of orientation with respect to the first direction parallel to the main surface of the liquid crystal polyester film, and the second degree of orientation is parallel to the main surface and orthogonal to the first direction. When the degree of orientation with respect to the second direction is set, the first degree of orientation / second degree of orientation, which is the ratio of the first degree of orientation to the second degree of orientation, is 0.95 to 1.04. Yes,
Third der degree of orientation than 60.0% of the liquid crystal polyester as measured by wide-angle X-ray scattering method in a direction parallel to the main surface is,
The liquid crystalline polyester includes repeating units represented by the formulas (1), (2) and (3),
The content of the repeating unit represented by the formula (1) with respect to the total amount of the repeating units represented by the formulas (1), (2) and (3) is 30 mol% or more and 80 mol% or less,
The content of the repeating unit represented by the formula (2) with respect to the total amount of the repeating units represented by the formulas (1), (2) and (3) is 10 mol% or more and 35 mol% or less,
The content of the repeating unit represented by the formula (3) with respect to the total amount of the repeating units represented by the formulas (1), (2) and (3) is 10 mol% or more and 35 mol% or less. Liquid crystalline polyester film.
(1) —O—Ar ¹ —CO—
(2) —CO—Ar ² —CO—
⁽³⁾ -X-Ar 3 -Y-
(In the formulas (1) to (3), Ar ¹ represents a phenylene group, a naphthylene group or a biphenylylene group, and Ar ² and Ar ³ are each independently a phenylene group, a naphthylene group, a biphenylene group or the following formula (4): X and Y each independently represents an oxygen atom or an imino group , and each hydrogen atom in the group represented by Ar ¹ , Ar ² and Ar ³ is independently a halogen atom. (It may be substituted with an atom, an alkyl group or an aryl group.)
^{(4) -Ar 4 -Z-Ar} 5 -
(In Formula (4), Ar ⁴ and Ar ⁵ each independently represent a phenylene group or a naphthylene group. Z represents an oxygen atom, a sulfur atom, a carbonyl group, a sulfonyl group, or an alkylidene group.)   The liquid crystal polyester film according to claim 1, wherein the third orientation degree is 60.0% or more and 80.0% or less. A liquid crystal polyester liquid composition comprising a liquid crystal polyester and a solvent,
The liquid crystalline polyester includes repeating units represented by the formulas (1), (2) and (3),
The content of the repeating unit represented by the formula (1) with respect to the total amount of the repeating units represented by the formulas (1), (2) and (3) is 30 mol% or more and 80 mol% or less,
The content of the repeating unit represented by the formula (2) with respect to the total amount of the repeating units represented by the formulas (1), (2) and (3) is 10 mol% or more and 35 mol% or less,
The content of the repeating unit represented by the formula (3) with respect to the total amount of the repeating units represented by the formulas (1), (2) and (3) is 10 mol% or more and 35 mol% or less,
The liquid crystal polyester liquid composition has a viscosity at 23 ° C. of 100 mPa · s or more and 1000 mPa · s or less,
In the liquid crystal polyester liquid composition, a mixture containing the liquid crystal polyester and the solvent has a temperature A [° C.] and a retention time B [hr] after reaching the temperature A [° C.] in formulas (5) and (6). And a liquid crystal polyester liquid composition obtained by heating and stirring under conditions satisfying (7).
(1) —O—Ar ¹ —CO—
(2) —CO—Ar ² —CO—
⁽³⁾ -X-Ar 3 -Y-
(In the formulas (1) to (3), Ar ¹ represents a phenylene group, a naphthylene group or a biphenylylene group, and Ar ² and Ar ³ are each independently a phenylene group, a naphthylene group, a biphenylene group or the following formula (4): X and Y each independently represents an oxygen atom or an imino group, and each hydrogen atom in the group represented by Ar ¹ , Ar and Ar ³ is independently a halogen atom. , May be substituted with an alkyl group or an aryl group.)
(4) -Ar ⁴ -Z-Ar ^5-
(In Formula (4), Ar ⁴ and Ar ⁵ each independently represent a phenylene group or a naphthylene group. Z represents an oxygen atom, a sulfur atom, a carbonyl group, a sulfonyl group, or an alkylidene group.)
(5) 120 ≦ A <200
(6) 3 ≦ B
(7) 19 ≦ (0.1A + B) <30 Furthermore, the liquid-crystal polyester liquid composition of Claim 3 obtained by heating and stirring on the conditions which satisfy | fill Formula (8).
(8) 130 ≦ A <180 A liquid crystal polyester liquid composition according to claim 3 or 4 is cast on a support to form a coating film,
Removing the solvent from the coating film,
Heating the coating film from which the solvent has been removed;
A method for producing a liquid crystal polyester film, comprising: separating the heated coating film and the support.

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