JP2022156738A - laminate - Google Patents

Abstract

To provide a laminate that can exhibit relative dielectric constants and dielectric loss tangents at lower levels as compared to the case where a polyimide film is used alone.SOLUTION: A laminate has a polyimide film, and a polyester layer that is laminated on at least one side of the polyimide film and is composed of a solvent-soluble liquid crystal polyester.SELECTED DRAWING: None

Description

The present invention relates to laminates.

In recent years, full-scale introduction of the 5th generation mobile communication system (hereinafter referred to as “5G”) has progressed. High-frequency and high-speed communication equipment in the GHz band used for such 5G (millimeter-wave radar for automobiles, antennas for smartphones, etc.) suffers greater transmission loss as the frequency increases. , the use of low-dielectric materials with low dielectric constants and low dielectric loss tangents for substrates and the like. Polyimide films have been mainly used as such low dielectric materials so far, but there is a demand for new materials having even lower dielectric constants and dielectric loss tangents. On the other hand, in recent years, attention has also been paid to liquid crystalline polyester as a low dielectric material having a low dielectric constant and a low dielectric loss tangent. For example, in Japanese Unexamined Patent Application Publication No. 2006-88426 (Patent Document 1), at least one structural unit selected from the group consisting of structural units derived from aromatic diamines and structural units derived from aromatic amines having a phenolic hydroxyl group is completely It has been proposed to produce a base film for a flexible printed wiring board using a liquid crystalline polyester containing 10 to 35 mol % of the structural unit.

JP-A-2006-88426

However, although Patent Document 1 describes up to the application of a liquid crystalline polyester composition using glass or a metal plate as a support, there is no mention of the idea of laminating the liquid crystalline polyester on a resin film. do not have.

The present invention has been made in view of the above-described problems of the prior art, and provides a laminate that can exhibit a lower dielectric constant and dielectric loss tangent than when a polyimide film is used alone. intended to provide

As a result of intensive research to achieve the above object, the present inventors have found that the laminate is a polyester composed of a polyimide film and a solvent-soluble liquid crystal polyester laminated on at least one surface of the polyimide film. The inventors have found that a lower dielectric constant and a lower dielectric loss tangent can be exhibited by providing a layer, and have completed the present invention.

That is, the laminate of the present invention includes a polyimide film,
A polyester layer made of a solvent-soluble liquid crystal polyester laminated on at least one surface of the polyimide film;
It is characterized by comprising

In the laminate of the present invention, the liquid crystalline polyester soluble in the solvent is
The following monomers (A) to (C):
[Monomer (A)] bifunctional aromatic hydroxycarboxylic acid,
[Monomer (B)] bifunctional aromatic dicarboxylic acid,
[Monomer (C)] at least one compound selected from the group consisting of bifunctional aromatic diols and bifunctional aromatic hydroxylamines;
At least one of the monomer (B) and the monomer (C) contains a compound for forming a flexible structural unit, and the content of the compound for forming a flexible structural unit is the above 20 to 40 mol % of the linear liquid crystal polymer chains relative to the total molar amount of the monomers (A) to (C) are the following monomers (D):
[Monomer (D)] an aromatic compound having 3 to 8 functional groups of at least one selected from the group consisting of a hydroxy group, a carboxyl group and an amino group;
and the content of the monomer (D) is 0.01 to 10 mol per 100 mol of the total molar amount of the monomers (A) to (C). Preferably.

Further, in the laminate of the present invention,
the monomer (A) is at least one selected from the group consisting of 4-hydroxybenzoic acid, 4-(4-hydroxyphenyl)benzoic acid, and 2-hydroxy-6-naphthoic acid;
The monomer (B) is at least one selected from the group consisting of 2,6-naphthalenedicarboxylic acid, isophthalic acid, terephthalic acid, 4,4'-biphenyldicarboxylic acid and diphenyl ether-4,4'-dicarboxylic acid. can be,
The monomer (C) is 3-aminophenol, 4-aminophenol, 1-amino-7-naphthol, 4,4′-biphenol, bisphenolfluorene, biscresolfluorene, 1,1′-bi-2-naphthol, At least one selected from the group consisting of methylhydroquinone, phenylhydroquinone, and 6-methyl-3-aminophenol, and
The compound for forming the flexible structural unit includes isophthalic acid, diphenyl ether-4,4′-dicarboxylic acid, 3-aminophenol, 6-methyl-3-aminophenol, 1-amino-7-naphthol, bisphenolfluorene, bis It is preferably at least one selected from the group consisting of cresol fluorene and 1,1'-bi-2-naphthol.

Further, in the laminate of the present invention, the monomer (D) is 3,5-dihydroxybenzoic acid, 1,3,5-trihydroxybenzene, 2,5-dihydroxyterephthalic acid, 1,5-dihydroxynaphthalene. -2,6-dicarboxylic acid, 1,6-dihydroxynaphthalene-2,5-dicarboxylic acid, 1,4-dihydroxy-2-naphthoic acid, 1,3,5-benzenetricarboxylic acid, 5-hydroxyisophthalic acid, and , and benzenetetracarboxylic acid.

ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to provide the laminated body which can exhibit a lower dielectric constant and a dielectric loss tangent compared with the case where a polyimide film is utilized independently.

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will now be described in detail with reference to its preferred embodiments. In this specification, unless otherwise specified, the notation "X to Y" for numerical values X and Y means "X or more and Y or less". In such notation, when only the numerical value Y is given a unit, the unit is applied to the numerical value X as well.

The laminate of the present invention comprises a polyimide film; and a polyester layer composed of a liquid crystalline polyester soluble in a solvent and laminated on at least one side of the polyimide film.

(polyimide film)
The polyimide film according to the present invention is not particularly limited, and any known polyimide film can be used as appropriate. In addition, as such a polyimide film, a commercially available product may be used. (registered trademark), Xenomax (registered trademark) manufactured by Toyobo Co., Ltd., and the like.

The thickness of such a polyimide film is not particularly limited, but the laminate can be used as a high frequency flexible printed circuit board, a high frequency flexible copper clad laminate, a high frequency flexible thin multilayer substrate, a high frequency component, Wi-Fi. (registered trademark) RF lines, Wi-Fi (registered trademark) antennas, millimeter wave band antennas, digital lines, millimeter wave radar parts, etc. 10 μm to 250 μm).

(polyester layer)
The polyester layer according to the present invention is made of solvent-soluble liquid crystalline polyester. Thus, the polyester layer according to the present invention is a layer formed of liquid crystalline polyester soluble in a solvent.

The liquid crystalline polyester that constitutes such a polyester layer is not particularly limited, and any liquid crystalline polyester having a property of being soluble in a solvent may be used. can. Liquid crystalline polyesters suitable for use in the present invention are described below.

<Liquid crystal polyester>
As liquid crystalline polyesters soluble in solvents, the following monomers (A) to (C):
[Monomer (A)] bifunctional aromatic hydroxycarboxylic acid,
[Monomer (B)] bifunctional aromatic dicarboxylic acid,
[Monomer (C)] at least one compound selected from the group consisting of bifunctional aromatic diols and bifunctional aromatic hydroxylamines;
can be suitably used. Examples of the liquid crystal polyester having a structural portion obtained by polymerizing such monomers (A) to (C) include, in addition to the polymers of the monomers (A) to (C), the monomers (A) to (C) ) having a liquid crystal polymer chain obtained by polymerization.

Further, such a liquid crystalline polyester soluble in a solvent is composed of the monomers (A) to (C), and at least one of the monomer (B) and the monomer (C) forms a flexible structural unit. and the content of the compound for forming the flexible structural unit is 20 to 40 mol% relative to the total molar amount of the monomers (A) to (C). The liquid crystal polymer chain is the following monomer (D):
[Monomer (D)] an aromatic compound having 3 to 8 functional groups of at least one selected from the group consisting of a hydroxy group, a carboxyl group and an amino group;
A liquid crystal polyester ( Such a liquid crystalline polyester is hereinafter sometimes simply referred to as "liquid crystalline polyester (I)"). Hereinafter, such monomers (A) to (D) will be described separately.

[Monomer (A)]
The monomer (A) is a bifunctional aromatic hydroxycarboxylic acid. Such a bifunctional aromatic hydroxycarboxylic acid is not particularly limited, and any known bifunctional aromatic hydroxycarboxylic acid that can be used in the production of a liquid crystal polyester can be appropriately used. Formula: HO-Ar-COOH (Ar represents a divalent aromatic group. Such a divalent aromatic group may have a substituent.) Use a compound represented by be able to. In the aromatic hydroxycarboxylic acid represented by such a formula: HO-Ar-COOH, Ar in the formula is, for example, a phenylene group, a naphthylene group, a biphenylene group, each of which may have a substituent. groups, terphenylene groups, and the like. In addition, the substituent that the divalent aromatic group as Ar may have is not particularly limited, and examples thereof include a fluorine atom, a chlorine atom, a bromine atom, a methyl group, an ethyl group, a propyl group, and a trifluoromethyl group. and a phenyl group.

As such a monomer (A), the following formula (1):
HO—Ar ¹ —COOH (1)
[Ar ¹ in the formula is a group selected from the group consisting of 1,4-phenylene, 2,6-naphthylene and 4,4′-biphenylene. ]
At least one compound selected from the group of compounds represented by can be preferably used. P-hydroxybenzoic acid, 4-(4-hydroxyphenyl)benzoic acid, and 2-hydroxy-6-naphthoic acid are preferable as the compound represented by formula (1). Moreover, as such a monomer (A), one type may be used alone, or two or more types may be used in combination.

[Monomer (B)]
The monomer (B) is a bifunctional aromatic dicarboxylic acid. Such a bifunctional aromatic dicarboxylic acid is not particularly limited, and any known bifunctional aromatic dicarboxylic acid that can be used in the production of liquid crystalline polyesters can be appropriately used. A compound represented by HOOC-Ar-COOH (Ar represents a divalent aromatic group, and the divalent aromatic group may have a substituent) can be used. In the aromatic dicarboxylic acid represented by the formula: HOOC-Ar-COOH, Ar has the same meaning as explained in the formula of the monomer (A). Further, in such a monomer (B), Ar in the formula: HOOC-Ar-COOH is not particularly limited, but for example, the following formula:

(wherein each R is independently one selected from the group consisting of a hydrogen atom, a fluorine atom, a chlorine atom, a bromine atom, a methyl group, an ethyl group, a propyl group, a trifluoromethyl group and a phenyl group, Z is a single bond or formula: -O-, -O-(CH ₂ ) ₂ -O-, -O-(CH ₂ ) ₆ -O-, -C(CF ₃ ) ₂ , -CO- and -SO ₂ is one group selected from the group consisting of groups represented by -.)
Groups selected from the groups represented by can be mentioned as suitable ones. In addition, a compound in which a carboxylic acid is bonded to adjacent carbon atoms in Ar (a divalent aromatic group) (for example, when Ar is naphthylene, 1,2-substituted or 2,2-substituted carboxylic acid groups are present adjacently) 3-substituted, 1,8-substituted compounds, etc.) are represented by the formula: HOOC-Ar-COOH, since acid dianhydride formation may proceed in parallel during the production of the liquid crystalline polyester depending on the reaction conditions employed. A compound in which a carboxylic acid is not bonded to an adjacent carbon atom in Ar can be more preferably used as the compound.

In addition, as such a monomer (B), from the viewpoint of being able to more efficiently achieve liquid crystal development and low dielectric loss tangent, and from the viewpoint of being able to further improve solvent solubility, the following Formula (2):
HOOC-Ar2-COOH ( ² )
[Ar ² in the formula has at least one substituent selected from the group consisting of a fluorine atom, a chlorine atom, a bromine atom, a methyl group, an ethyl group, a propyl group, a trifluoromethyl group and a phenyl group; 1,4-phenylene, 1,3-phenylene, 1,4-naphthylene, 1,5-naphthylene, 1,7-naphthylene (also known as 2,8-naphthylene), 1,3-naphthylene ( Also known as: 2,4-naphthylene), 1,6-naphthylene (also known as 2,5-naphthylene), 2,6-naphthylene, 2,7-naphthylene, and the following formula (2-1):

(Z in the formula is a single bond or formula: -O-, -O-(CH ₂ ) ₂ -O-, -O-(CH ₂ ) ₆ -O-, -C(CF ₃ ) ₂ - is one group selected from the group consisting of groups represented by -CO- and -SO ₂ -, wherein the bonds represented by *1 and *2 are respectively the It is a bond that bonds with the COOH group.)
is a group selected from the group consisting of groups represented by (thus, each group that can be selected as Ar ² (including the group represented by the above formula (2-1)) is unsubstituted or may have at least one of the substituents, i.e., each group that can be selected as Ar ² is an unsubstituted group or substituted with at least one of the substituents It becomes the base that was made.). ]
At least one compound selected from the group of compounds represented by is preferred. As described above, each group that can be selected as Ar ² (including the group represented by the above formula (2-1)) includes a fluorine atom, a chlorine atom, a bromine atom, a methyl group, an ethyl group, and a propyl group. , a trifluoromethyl group and a phenyl group.

Further, when Ar ² is a group represented by the above formula (2-1), Z in formula (2-1) is a single bond or the formula: -O-, -O-(CH ₂ ) ₂ -O-, -O-(CH ₂ ) ₆ -O-, -C(CF ₃ ) ₂ -, -CO- and one selected from the group consisting of groups represented by -SO ₂ - is the base. As Z in such formula (2-1), since it is possible to obtain a higher effect from the viewpoint of lowering the dielectric loss tangent and improving solvent solubility, a group represented by the formula: -O- -CO- and -SO ₂ - are preferred, and a group represented by the formula: -O- is more preferred. Furthermore, when Ar ² is a group represented by the above formula ( ^2-1 ), it is possible to obtain a higher effect from the viewpoint of lowering the dielectric loss tangent. -1), Z is a single bond, and the bonds represented by *1 and *2 are bonded to the 3,3′ or 4,4′ positions (i.e., 3,3'-biphenylene, 4,4'-biphenylene) can be preferably used. Each group selected as Ar ² has at least one substituent selected from the group consisting of a fluorine atom, a chlorine atom, a bromine atom, a methyl group, an ethyl group, a propyl group, a trifluoromethyl group and a phenyl group. You may have one. That is, each group selected as Ar ² may be a group in which at least one of the substituents is substituted with a hydrogen atom. As such a substituent, a methyl group, a phenyl group, and a trifluoromethyl group are more preferable, since it is possible to obtain a higher effect from the viewpoint of lowering the dielectric loss tangent and improving solvent solubility. more preferably a phenyl group.

In addition, the compound represented by the formula (2) has the viewpoint that it is possible to more efficiently achieve liquid crystallinity and low dielectric loss tangent, and it is possible to further improve solvent solubility. From the viewpoint of terephthalic acid, isophthalic acid, 4,4'-biphenyldicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid , diphenyl ether-4,4′-dicarboxylic acid (also known as 4,4′-dicarboxydiphenyl ether) is more preferable, and terephthalic acid, isophthalic acid, and 2,6-naphthalenedicarboxylic acid are more preferable.

In the compound represented by the formula (2), the compound for forming the flexible structural unit includes Ar ² being a fluorine atom, a chlorine atom, a bromine atom, a methyl group, an ethyl group, a propyl group, a trifluoro It may have at least one substituent selected from the group consisting of a methyl group and a phenyl group, and 1,3-phenylene, 1,7-naphthylene (also known as 2,8-naphthylene), 1,3- Naphthylene (also known as 2,4-naphthylene), 1,6-naphthylene (also known as 2,5-naphthylene), wherein Z is a single bond and the bonds represented by *1 and *2 are 3,4' A group represented by the formula (2-1) bonded to the position, 3,3′ position, 3,2′ position or 2,2′ position, and Z is the formula: —O—, from the group consisting of groups represented by -O-(CH ₂ ) ₂ -O-, -O-(CH ₂ ) ₆ -O-, -C(CF ₃ ) ₂ -, -CO- and -SO ₂ - A compound represented by the above formula (2), which is a group selected from the group consisting of groups represented by the above formula (2-1), which is one selected type, can be mentioned. Here, the "compound for forming a flexible structural unit" means, for example, a compound having a structural moiety such as 1,3-phenylene, when the compound is used to form a structure within the liquid crystal polymer chain. In addition, it is possible for the polymer chain to form a bent chain due to the structure derived from the compound instead of having a straight linear structure, and forms a bent structural portion (structural unit) in the polymer chain. A compound used for On the other hand, in the compound represented by the formula (2), the compound for forming the linear structural portion (structural unit) (other than the compound for forming the flexible structural unit) has Ar ² as a fluorine atom , a chlorine atom, a bromine atom, a methyl group, an ethyl group, a propyl group, a trifluoromethyl group and a phenyl group. ,4′-biphenylene, 1,4-naphthylene, 1,5-naphthylene, 2,6-naphthylene, and 2,7-naphthylene, represented by the above formula (2), which is a group selected from the group consisting of can be mentioned.

In addition, among the compounds represented by the formula (2), it is said that it is possible to more efficiently achieve liquid crystal development and low dielectric loss tangent, and that it is possible to further improve solvent solubility. From the point of view, 2,6-naphthalenedicarboxylic acid, isophthalic acid, terephthalic acid, 4,4′-biphenyldicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid , 4,4′-dicarboxydiphenyl ether is preferred, 2,6-naphthalenedicarboxylic acid, isophthalic acid, terephthalic acid, 4,4′-biphenyldicarboxylic acid, 4,4′-dicarboxydiphenyl ether are more preferred, and 2,6 -naphthalenedicarboxylic acid and 4,4'-dicarboxydiphenyl ether are more preferred, and 2,6-naphthalenedicarboxylic acid is particularly preferred.

Further, when at least one of the compounds used as such a monomer (B) is a compound for forming a flexible structural unit, the compound for forming a flexible structural unit may have liquid crystallinity or low liquid crystallinity. From the viewpoint that the dielectric loss tangent can be more efficiently achieved, and the viewpoint that the solvent solubility can be further improved, isophthalic acid, 1,7-naphthalenedicarboxylic acid, 1,3-naphthalenedicarboxylic acid , 1,6-naphthalenedicarboxylic acid and 4,4′-dicarboxydiphenyl ether are preferred, and isophthalic acid is particularly preferred.

[Monomer (C)]
The monomer (C) is at least one compound selected from the group consisting of bifunctional aromatic diols and bifunctional aromatic hydroxyamines.

Such a bifunctional aromatic diol is not particularly limited, and a known bifunctional aromatic diol that can be used in the production of liquid crystalline polyesters can be appropriately used. A compound represented by Ar-OH (Ar represents a divalent aromatic group, and the divalent aromatic group may have a substituent) can be used. In the aromatic diol represented by the formula: HO--Ar--OH, Ar has the same meaning as explained in the formula of the monomer (A). Further, in such a monomer (C), Ar in the formula: HO-Ar-OH is not particularly limited, but for example, the following formula:

(wherein each R is independently one selected from the group consisting of a hydrogen atom, a fluorine atom, a chlorine atom, a bromine atom, a methyl group, an ethyl group, a propyl group, a trifluoromethyl group and a phenyl group, Z is a single bond or formula: -O-, -CH ₂ -, -CH(CH ₃ )-, -C(CH ₃ ) ₂ -, -C(CF ₃ ) ₂ -, -CPh ₂ -, -CO- , -S- and -SO ₂ -.)
Groups selected from the groups represented by can be mentioned as suitable ones.

In addition, the bifunctional aromatic diol used as such a monomer (C) has the viewpoint of being able to more efficiently achieve liquid crystallinity and low dielectric loss tangent, and further improving solvent solubility. is possible, the following formula (3):
HO—Ar ³ —OH (3)
[Ar ³ in the formula has at least one substituent selected from the group consisting of a fluorine atom, a chlorine atom, a bromine atom, a methyl group, an ethyl group, a propyl group, a trifluoromethyl group and a phenyl group; 1,4-phenylene, 1,3-phenylene, 1,2-phenylene, 1,2-naphthylene, 1,4-naphthylene, 1,5-naphthylene, 1,7-naphthylene (also known as 2 ,8-naphthylene), 1,8-naphthylene, 2,3-naphthylene, 1,3-naphthylene (also known as 2,4-naphthylene), 1,6-naphthylene (also known as 2,5-naphthylene), 2, 6-naphthylene, 2,7-naphthylene, and the following formula (3-1):

(Z in the formula is a single bond or formula: -O-, -CH ₂ -, -CH(CH ₃ )-, -C(CH ₃ ) ₂ -, -C(CF ₃ ) ₂ -, - one group selected from the group consisting of groups represented by CPh ₂ -, -CO-, -S- and -SO ₂ -, wherein the group represented by the formula: -CPh ₂ - Ph represents a phenyl group, and the bonds represented by *1 and *2 are the bonds bonded to the OH group in formula (3).)
A group selected from the group consisting of groups represented by (thus, each group that can be selected as Ar ³ (including the group represented by the above formula (3-1)) is unsubstituted or may have at least one of said substituents, i.e., each group that can be selected as Ar ³ is an unsubstituted group or substituted with at least one of said substituents It becomes the base that was made.)]
At least one compound selected from the group of compounds represented by is preferred. As described above, each group that can be selected as Ar ³ (including the group represented by formula (3-1) above) includes a fluorine atom, a chlorine atom, a bromine atom, a methyl group, an ethyl group, and a propyl group. , a trifluoromethyl group and a phenyl group.

Further, when Ar ³ is a group represented by the above formula (3-1), Z in formula (3-1) is a single bond or the formula: -O-, -CH ₂ -, - Group consisting of groups represented by CH(CH ₃ )—, —C(CH ₃ ) ₂ —, —C(CF ₃ ) ₂ —, —CPh ₂ —, —CO—, —S— and —SO ₂ — is one group selected from As Z in such formula (3-1), since it is possible to obtain a higher effect from the viewpoint of lowering the dielectric loss tangent and improving solvent solubility, a single bond, -O- or -CO- A single bond or -CO- is more preferred. In addition, as the group represented by the above formula (3-1) when Z is a single bond, the bonds represented by 1 and *2 are at the 2,2' positions, 3,3' positions, or Groups bonded to the 4,4' positions (ie, 2,2'-biphenylene, 3,3'-biphenylene, 4,4'-biphenylene) can be preferably used. Each group selected as Ar ³ has at least one substituent selected from the group consisting of a fluorine atom, a chlorine atom, a bromine atom, a methyl group, an ethyl group, a propyl group, a trifluoromethyl group and a phenyl group. You may have one. That is, each group selected as Ar ³ may be a group in which at least one of the substituents is substituted with a hydrogen atom. As such a substituent, a methyl group, a phenyl group, and a trifluoromethyl group are more preferable, since it is possible to obtain a higher effect from the viewpoint of lowering the dielectric loss tangent and improving solvent solubility. more preferably a phenyl group.

In addition, as such an aromatic diol, resorcinol, catechol, etc., can be used from the viewpoint of being able to more efficiently achieve liquid crystallinity and low dielectric loss tangent, and from the viewpoint of being able to further improve solvent solubility. , hydroquinone, 1,2-dihydroxynaphthalene, 1,3-dihydroxynaphthalene, 1,4-dihydroxynaphthalene, 1,5-dihydroxynaphthalene, 1,7-dihydroxynaphthalene, 1,8-dihydroxynaphthalene, 2,3-dihydroxy naphthalene, 1,6-dihydroxynaphthalene, 2,6-dihydroxynaphthalene, 2,7-dihydroxynaphthalene, 1,1′-bi-2-naphthol (BINOL), bisphenolfluorene, biscresolfluorene, methylhydroquinone (MHQ), Phenylhydroquinone (PhHQ), 1,4-dihydroxy-2-methylnaphthalene, 4,4′-biphenol are more preferred, resorcinol, catechol, hydroquinone, 2,3-dihydroxynaphthalene, BINOL, bisphenolfluorene, biscresolfluorene, MHQ , PhHQ and 4,4'-biphenol are more preferred, and resorcinol, catechol, hydroquinone, 2,3-dihydroxynaphthalene, BINOL, bisphenolfluorene, biscresolfluorene, MHQ and 4,4'-biphenol are particularly preferred.

In addition, the bifunctional aromatic hydroxyamine used as the monomer (C) is not particularly limited, and a known bifunctional aromatic hydroxyamine that can be used for the production of liquid crystalline polyester can be appropriately used. can be formed, for example, by the formula: HO--Ar--NH ₂ (wherein Ar represents a divalent aromatic group. The divalent aromatic group may have a substituent.) Compounds represented are available. In the aromatic hydroxyamine represented by the formula: HO--Ar--NH ₂ , Ar has the same meaning as explained in the formula of the monomer (A). Ar in the formula: HO-Ar- _NH2 is

(In the formula, each R is independently one selected from the group consisting of a hydrogen atom, a fluorine atom, a chlorine atom, a bromine atom, a methyl group, an ethyl group, a propyl group, a trifluoromethyl group and a phenyl group. )
Groups selected from the groups represented by can be mentioned as suitable ones. In addition, a compound in which a hydroxy group and an amino group are bonded to adjacent carbon atoms in Ar (a divalent aromatic group) (for example, when Ar is naphthylene, a hydroxy group and an amino group are adjacent to each other 1, Disubstituted, 2,3-substituted, 1,8-substituted compounds, etc.), depending on the reaction conditions employed, oxazolization may proceed in parallel, so the above formula: HO-Ar-NH ₂ As the compound represented by, a compound in which a hydroxyl group and an amino group are not bonded to adjacent carbon atoms in Ar can be used more preferably.

In addition, as such a bifunctional aromatic hydroxyamine, it is possible to more efficiently achieve the development of liquid crystallinity and a low dielectric loss tangent, and the viewpoint that it is possible to further improve solvent solubility. From, the following formula (4):
HO-Ar4- _NH2 ( ⁴ )
[Ar ⁴ in the formula has at least one substituent selected from the group consisting of a fluorine atom, a chlorine atom, a bromine atom, a methyl group, an ethyl group, a propyl group, a trifluoromethyl group and a phenyl group; 1,4-phenylene, 1,3-phenylene, 3,3′-biphenylene, 4,4′-biphenylene, 1,4-naphthylene, 1,5-naphthylene, 1,7-naphthylene, 2 ,8-naphthylene, 1,3-naphthylene, 2,4-naphthylene, 1,6-naphthylene, 2,5-naphthylene, 2,6-naphthylene, and a group selected from the group consisting of 2,7-naphthylene is. ]
At least one compound selected from the group of compounds represented by is preferred. Each group that can be selected as Ar ⁴ is a substituent selected from the group consisting of a fluorine atom, a chlorine atom, a bromine atom, a methyl group, an ethyl group, a propyl group, a trifluoromethyl group and a phenyl group, as described above. It may have at least one group. That is, each group selected as Ar ⁴ may be a group in which at least one of the substituents is substituted with a hydrogen atom. As such a substituent, a methyl group, a phenyl group, and a trifluoromethyl group are more preferable, since it is possible to obtain a higher effect from the viewpoint of lowering the dielectric loss tangent and improving solvent solubility. more preferably a phenyl group.

It should be noted that the compound represented by the formula (4) has the viewpoint that it is possible to more efficiently achieve liquid crystallinity and low dielectric loss tangent, and that it is possible to further improve solvent solubility. From the point of view, 3-aminophenol, 4-aminophenol, 1-amino-3-naphthol (alias: 4-amino-2-naphthol), 1-amino-4-naphthol (alias: 4-amino-1-naphthol) , 2-amino-4-naphthol (alias: 3-amino-1-naphthol), 2-amino-6-naphthol (alias: 6-amino-2-naphthol), 2-amino-7-naphthol (7-amino -2-naphthol), 2-amino-8-naphthol (7-amino-1-naphthol), 1-amino-5-naphthol (alias: 5-amino-1-naphthol), 8-amino-2-naphthol ( Alias: 1-amino-7-naphthol), 6-amino-1-naphthol (alias: 2-amino-5-naphthol), 5-amino-2-naphthol (alias: 1-amino-6-naphthol), 6 -Methyl-3-aminophenol (6-Me-3-AP), 3-methyl-4-aminophenol (3-Me-4-AP) are more preferred, 3-aminophenol, 4-aminophenol, 8- Amino-2-naphthol, 6-Me-3-AP and 3-Me-4-AP are more preferred, and 3-aminophenol, 4-aminophenol and 8-amino-2-naphthol are particularly preferred.

In the compound represented by the above formula (3) and the compound represented by the above formula (4), the compound for forming the flexible structural unit includes, for example, Ar ³ in the formula is a fluorine atom, a chlorine atom, It may have at least one substituent selected from the group consisting of a bromine atom, a methyl group, an ethyl group, a propyl group, a trifluoromethyl group and a phenyl group, and 1,3-phenylene, 1,2 -phenylene, 1,2-naphthylene, 1,7-naphthylene (also known as 2,8-naphthylene), 1,8-naphthylene, 2,3-naphthylene, 1,3-naphthylene (also known as 2,4-naphthylene) , 1,6-naphthylene (also known as 2,5-naphthylene), 2,7-naphthylene, said Z is a single bond and the bonds represented by *1 and *2 are at positions 3,4′, 3 , a group represented by the formula (3-1) bonded to the 3′ position, the 3,2′ position or the 2,2′ position, and the Z is the formula: —O—, —CH ₂ — , -CH(CH ₃ )-, -C(CH ₃ ) ₂ -, -C(CF ₃ ) ₂ -, -CPh ₂ -, -CO-, -S- and -SO ₂ - A compound represented by the above formula ( ³ ), which is a group selected from the group consisting of groups represented by the above formula (3-1), which is one selected from the group consisting of: may have at least one substituent selected from the group consisting of a fluorine atom, a chlorine atom, a bromine atom, a methyl group, an ethyl group, a propyl group, a trifluoromethyl group and a phenyl group; - phenylene, 1,7-naphthylene, 2,8-naphthylene, 1,3-naphthylene, 2,4-naphthylene, 1,6-naphthylene, 2,5-naphthylene, 2,7-naphthylene The compound represented by the above formula (4) can be mentioned. On the other hand, in the compound represented by the above formula (3) and the compound represented by the above formula (4), a compound for forming a structural portion (structural unit) having a linear structure (other than a compound for forming a flexible structural unit) ) is represented by, for example, any formula (each formula) selected from the above formula (3) and the above formula (4), and Ar ³ or Ar ⁴ in the formula is fluorine 1,4-phenylene, optionally having at least one substituent selected from the group consisting of an atom, a chlorine atom, a bromine atom, a methyl group, an ethyl group, a propyl group, a trifluoromethyl group and a phenyl group; 4,4′-biphenylene, 1,4-naphthylene, 1,5-naphthylene, 2,6-naphthylene, and 4,4 where Z is a single bond and the bonds represented by *1 and *2 are 4,4 Examples include compounds that are groups selected from the group consisting of the groups represented by the formula (3-1) bonded to the '-position, the 3,5'-position, or the 5,3'-position.

In addition, as the bifunctional aromatic hydroxyamine, it is possible to more efficiently achieve the development of liquid crystallinity and a low dielectric loss tangent, and from the viewpoint that it is possible to further improve solvent solubility. , among others, 3-aminophenol, 4-aminophenol, 1-amino-5-naphthol (alias: 5-amino-1-naphthol), 8-amino-2-naphthol (alias: 1-amino-7-naphthol) , 6-amino-1-naphthol (alias: 2-amino-5-naphthol), 5-amino-2-naphthol (alias: 1-amino-6-naphthol), 6-methyl-3-aminophenol (6- Me-3-AP), 3-methyl-4-aminophenol (3-Me-4-AP) are more preferred, 3-aminophenol, 4-aminophenol, 8-amino-2-naphthol (alias: 1- amino-7-naphthol), 6-amino-1-naphthol (alias: 2-amino-5-naphthol), 5-amino-2-naphthol (alias: 1-amino-6-naphthol), 6-methyl-3 -Aminophenol (6-Me-3-AP), 3-methyl-4-aminophenol (3-Me-4-AP) are more preferred, 3-aminophenol, 4-aminophenol, 8-amino-2- Naphthol (also known as 1-amino-7-naphthol) is particularly preferred.

In addition, as the bifunctional aromatic diol, from the viewpoint of being able to more efficiently achieve liquid crystallinity and low dielectric loss tangent, and from the viewpoint of being able to further improve solvent solubility, resorcinol, catechol, hydroquinone, 1,4-dihydroxynaphthalene, 1,5-dihydroxynaphthalene, 1,7-dihydroxynaphthalene, 1,8-dihydroxynaphthalene, 2,3-dihydroxynaphthalene, 1,6-dihydroxynaphthalene, 2, 6-dihydroxynaphthalene and 2,7-dihydroxynaphthalene, BINOL, bisphenolfluorene, biscresolfluorene, methylhydroquinone (MHQ), phenylhydroquinone (PhHQ), 1,4-dihydroxy-2-methylnaphthalene, 4,4' -biphenol is more preferred, resorcinol, catechol, hydroquinone, 2,3-dihydroxynaphthalene, BINOL, bisphenolfluorene, biscresolfluorene, MHQ, PhHQ, 4,4'-biphenol is more preferred, resorcinol, catechol, 2,3- Dihydroxynaphthalene is particularly preferred.

Further, when at least one of the compounds used as such monomers (C) is a compound for forming a flexible structural unit, the compound for forming a flexible structural unit may exhibit liquid crystallinity or reduce liquid crystallinity. From the viewpoint that the dielectric loss tangent can be achieved more efficiently and that the solvent solubility can be further improved, 3-aminophenol, 1-amino-7-naphthol (also known as 8-amino -2-naphthol) and 6-methyl-3-aminophenol are preferred, and 3-aminophenol and 1-amino-7-naphthol (also known as 8-amino-2-naphthol) are particularly preferred.

[Monomer (D)]
The monomer (D) is an aromatic compound having 3 to 8 functional groups of at least one selected from the group consisting of hydroxy groups, carboxy groups and amino groups. In the aromatic compound having 3 to 8 such functional groups, the functional group can exhibit higher effects in terms of liquid crystal development, low dielectric loss tangent, and solvent solubility. , hydroxy group and carboxy group are preferred.

Examples of such a monomer (D) include the following general formula (I):

(In the formula, each X independently represents a hydroxy group (hydroxyl group), a carboxy group, an amino group or hydrogen, and at least one of the plurality of X is selected from the group consisting of a hydroxy group, a carboxy group and an amino group. represents one type of functional group, and n represents an integer of 0 to 2.)
and compounds represented by the following general formula (II):

(Wherein Y is a single bond, or formulas: -O-, -CO-, -S-, -SO ₂ -, -CH ₂ -, -C(CH ₃ ) ₂ - and -C(CF ₃ ) ₂ - is one group selected from the group consisting of groups represented by -, each X independently represents a hydroxy group (hydroxyl group), a carboxy group, an amino group or hydrogen, and at least three of a plurality of X represents at least one functional group selected from the group consisting of a hydroxy group, a carboxy group and an amino group.)
A compound represented by can be preferably used.

Examples of aromatic compounds having 3 to 8 such functional groups include 2,5-dihydroxyterephthalic acid (2,5-DHTPA), 1,5-dihydroxynaphthalene-2,6-dicarboxylic acid ( 1,5-DONDC), 1,6-dihydroxynaphthalene-2,5-dicarboxylic acid, 1,4-dihydroxy-2-naphthoic acid, tetrahydroxyterephthalic acid, 1,3,5-benzenetricarboxylic acid (also known as trimesin acid (1,3,5-BTCA)), 3,5-dihydroxybenzoic acid (alias: α-resorcylic acid (3,5-DHBA)), 1,3,5-trihydroxybenzene (alias: phloroglucinol (1,3,5-BTOH)), benzenetetracarboxylic acid, benzenepentacarboxylic acid, benzenehexacarboxylic acid, naphthalenetricarboxylic acid, naphthalenetetracarboxylic acid, naphthalenepentacarboxylic acid, naphthalenehexacarboxylic acid, naphthaleneheptacarboxylic acid, naphthalene octacarboxylic acid, 5-hydroxyisophthalic acid, diaminobenzenedicarboxylic acid, diaminonaphthalenedicarboxylic acid, dihydroxyanthracenedicarboxylic acid, diaminoanthracenedicarboxylic acid, 3,3′-dihydroxybenzidine, 4,6-dihydroxy-1,3-phenylene diamine, 4,4′-sulfonylbis(2-aminophenol), 4,4′-(propane-2,2-diyl)bis(2-aminophenol), 4,4′-(perfluoropropane-2, 2-diyl)bis(2-aminophenol), 3,3′,4,4′-tetraaminodiphenyl ether, 5,5′-methylenebis(2-aminobenzoic acid) and the like can be mentioned as suitable ones.

In addition, among aromatic compounds (monomer (D)) having 3 to 8 such functional groups, it is possible to obtain higher effects in terms of liquid crystal development, low dielectric loss tangent, and solvent solubility. Therefore, 3,5-dihydroxybenzoic acid, 1,3,5-trihydroxybenzene, 2,5-dihydroxyterephthalic acid, 1,5-dihydroxynaphthalene-2,6-dicarboxylic acid, 1,6-dihydroxy More preferred are naphthalene-2,5-dicarboxylic acid, 1,4-dihydroxy-2-naphthoic acid, 1,3,5-benzenetricarboxylic acid, 5-hydroxyisophthalic acid, and benzenetetracarboxylic acid, and 2,5-dihydroxyterephthalic acid. acid, 1,5-dihydroxynaphthalene-2,6-dicarboxylic acid, 1,6-dihydroxynaphthalene-2,5-dicarboxylic acid, 1,4-dihydroxy-2-naphthoic acid, 1,3,5-benzenetricarboxylic acid is more preferred, and 2,5-dihydroxyterephthalic acid, 1,5-dihydroxynaphthalene-2,6-dicarboxylic acid, and 1,6-dihydroxynaphthalene-2,5-dicarboxylic acid are more preferred, and 2,5-dihydroxyterephthalic acid is particularly preferred.

Next, the liquid crystalline polyester obtained by using such monomers (A) to (D) will be described. In the present invention, the solvent-soluble liquid crystalline polyester is a polymer of the monomers (A) to (C) or a liquid crystal polymer chain obtained by polymerizing the monomers (A) to (C), as described above. Among them, the liquid crystalline polyester (I) is preferable. The liquid crystalline polyester (I) suitable as a liquid crystalline polyester soluble in a solvent is composed of the monomers (A) to (C), and at least one of the monomers (B) and (C) is bent. a compound for forming a flexible structural unit, and the content of the compound for forming a flexible structural unit is 20 to 40 mol% relative to the total molar amount of the monomers (A) to (C). Linear liquid crystal polymer chains are bonded via the monomer (D), and the content of the monomer (D) is based on the total molar amount of 100 mol of the monomers (A) to (C). It is a liquid crystalline polyester with a ratio of 0.01 to 10 moles. The liquid crystalline polyester (I) suitable for the present invention will be described below.

<Regarding the structure of the liquid crystal polyester (I)>
The liquid crystal polyester (I) has a structure in which specific linear liquid crystal polymer chains composed of the monomers (A) to (C) are bonded through the monomer (D).

<Linear Liquid Crystal Polymer Chain>
The linear liquid crystal polymer chain is a polymer chain composed of the above monomers (A) to (C). That is, such a linear liquid crystal polymer chain includes the structural unit (i) derived from the monomer (A), the structural unit (ii) derived from the monomer (B), and the monomer (C). It contains the derived structural unit (iii).

As the structural unit (i) derived from such monomer (A), the following formula (i):
-O-Ar-CO- (i)
[Ar in the formula represents a divalent aromatic group (more preferably, such Ar is Ar ¹ in the above formula (1)). In addition, the said divalent aromatic group may have a substituent. ]
Structural units represented by can be mentioned as suitable ones. Further, as the structural unit (ii) derived from the monomer (B), the following formula (ii):
-OC-Ar-CO- (ii)
[Ar in the formula represents a divalent aromatic group (more preferably, such Ar is Ar ² in the above formula (2)). In addition, the said divalent aromatic group may have a substituent. ]
Structural units represented by can be mentioned as suitable ones. Furthermore, as the structural unit (iii) derived from the monomer (C), the following formulas (iii) to (iv):
-O-Ar-O- (iii)
-O-Ar-NH- (iv)
[Ar in each formula represents a divalent aromatic group (wherein Ar in formula (iii) is more preferably Ar ³ in formula (3) above, and Ar in formula (iv) is Ar ⁴ in the above formula (4) is more preferable). In addition, the said divalent aromatic group may have a substituent. ]
Structural units represented by can be mentioned as suitable ones.

In such a linear liquid crystal polymer chain, the content of the monomer (A) is preferably 20 to 70 mol% relative to the total molar amount of the monomers (A) to (C). More preferably ~60 mol%. By setting the content of the monomer (A) within the above range, there is a tendency to obtain higher effects in terms of the development of liquid crystallinity, lower dielectric loss tangent, and solvent solubility. In particular, by setting the content of the monomer (A) to the above lower limit or more, it is possible to further improve the effects such as the development of liquid crystallinity and the reduction of the dielectric loss tangent. can be improved.

In the linear liquid crystal polymer chain, the content of the monomer (B) is preferably 10 to 50 mol% with respect to the total molar amount of the monomers (A) to (C). More preferably ~40 mol%. By setting the content of the monomer (B) within the above range, there is a tendency to obtain higher effects in terms of the development of liquid crystallinity, low dielectric loss tangent, and solvent solubility. In particular, by setting the content of the monomer (B) to the lower limit or more, the solvent solubility can be further improved. It becomes possible.

Furthermore, in the linear liquid crystal polymer chain, the content of the monomer (C) is preferably 10 to 50 mol% with respect to the total molar amount of the monomers (A) to (C). More preferably ~40 mol%. By setting the content of the monomer (C) within the above range, there is a tendency to obtain higher effects in terms of the development of liquid crystallinity, low dielectric loss tangent, and solvent solubility. In particular, by setting the content of the monomer (C) to the above lower limit or more, it is possible to further improve solvent solubility. can be improved. In the present invention, the preferred range of the content of each structural unit derived from the monomers (A) to (C) is the same as the content of the monomers (A) to (C).

Furthermore, in such a linear liquid crystal polymer chain, the total amount of the monomers (B) to (C) with respect to 100 parts by weight of the monomer (A) is 50 to 200 parts by weight (more preferably 55 to 190 parts by weight, More preferably 60 to 180). When the total amount of the monomers (B) to (C) is within the above range, it is possible to develop liquid crystallinity, reduce dielectric loss tangent, and further improve solvent solubility. In particular, by setting the total amount of the monomers (B) to (C) to the above lower limit or more, it is possible to further improve the solvent solubility, and on the other hand, by setting the total amount to the above upper limit or less, the liquid crystallinity and the low dielectric loss tangent can be further improved. can be improved.

Further, in the linear liquid crystal polymer chain composed of the monomers (A) to (C), at least one of the monomer (B) and the monomer (C) contains a compound for forming a flexible structural unit. I'm in. In order to satisfy such conditions, for example, a monomer (A), a monomer (B) containing a compound for forming a flexible structural unit, and a monomer (C) containing no compound for forming a flexible structural unit are mixed. It may be used in combination, and the monomer (A), the monomer (B) that does not contain a compound for forming a flexible structural unit, and the monomer (C) that contains a compound for forming a flexible structural unit are used in combination. Alternatively, the monomer (A), the monomer (B) containing the compound for forming the flexible structural unit, and the monomer (C) containing the compound for forming the flexible structural unit may be used in combination. . Further, when the monomer (B) is used as one containing a compound for forming a flexible structural unit, the monomer (B) may consist only of a compound for forming a flexible structural unit, or may be It may consist of a compound for forming structural units and other compounds. Similarly, when the monomer (C) is used as containing a compound for forming a flexible structural unit, the monomer (C) may consist only of a compound for forming a flexible structural unit, or may be It may be composed of a compound for forming a structural unit and a compound other than that.

Thus, the "compound contained as the monomer (B)" constituting the linear liquid crystal polymer chain and the "compound contained as the monomer (C)" constituting the linear liquid crystal polymer chain By using at least one of them as a compound for forming the flexible structural unit, it is possible to include a flexible structural portion in the linear liquid crystal polymer chain, thereby improving liquid crystallinity and solvent solubility. can be expressed. In the compound for forming such a flexible structural unit, Ar ² is selected from the group consisting of a fluorine atom, a chlorine atom, a bromine atom, a methyl group, an ethyl group, a propyl group, a trifluoromethyl group and a phenyl group. and 1,3-phenylene, 1,7-naphthylene (also known as 2,8-naphthylene), 1,3-naphthylene (also known as 2,4-naphthylene ), and 1,6-naphthylene (also known as 2,5-naphthylene), wherein Z is a single bond and the bonds represented by *1 and *2 are at positions 3,4′ and 3,3′. , the group represented by the formula (2-1) bonded to the positions 3, 2' or 2, 2', and the Z is the formula: -O-, -O-(CH ₂ ) ₂ -O-, -O-(CH ₂ ) ₆ -O-, -C(CF ₃ ) ₂ -, -CO- and -SO ₂ - is one selected from the group consisting of groups represented by A group of compounds represented by the above formula (2), which is a group selected from the group consisting of groups represented by the above formula (2-1); Ar ³ is a fluorine atom, a chlorine atom, a bromine atom, a methyl group, or an ethyl group, propyl group, trifluoromethyl group and phenyl group, and 1,3-phenylene, 1,2-phenylene, 1,2- Naphthylene, 1,7-naphthylene (also known as 2,8-naphthylene), 1,8-naphthylene, 2,3-naphthylene, 1,3-naphthylene (also known as 2,4-naphthylene), 1,6-naphthylene ( Also known as: 2,5-naphthylene) and a group selected from the group consisting of 2,7-naphthylene (more preferably 1,3-phenylene, 1,7-naphthylene (also known as 2,8-naphthylene), 1 ,3-naphthylene (also known as 2,4-naphthylene) and 1,6-naphthylene (also known as 2,5-naphthylene)), wherein Z is a single bond and *1 and * A group represented by the above formula (3-1) in which the bond represented by 2 is bonded to the 3,4′ position, the 3,3′ position, the 3,2′ position or the 2,2′ position , and Z is of the formula: —O—, —CH ₂ —, —CH(CH ₃ )—, —C(CH ₃ ) ₂ —, —C(CF ₃ ) ₂ —, —CPh ₂ —, —CO The above formula which is a group selected from the group consisting of the groups represented by the above formula (3-1), which is one selected from the group consisting of groups represented by -, -S- and -SO ₂ - Group of compounds represented by (3); , Ar ⁴ may have at least one substituent selected from the group consisting of a fluorine atom, a chlorine atom, a bromine atom, a methyl group, an ethyl group, a propyl group, a trifluoromethyl group and a phenyl group; and 1,3-phenylene, 1,7-naphthylene, 2,8-naphthylene, 1,3-naphthylene, 2,4-naphthylene, 1,6-naphthylene, 2,5-naphthylene and 2,7- At least one compound selected from the group consisting of the group of compounds represented by the above formula (4), which is a group selected from the group consisting of naphthylene, can be preferably used.

In addition, among such compounds for forming a flexible structural unit, isophthalic acid (monomer (B) one), diphenyl ether-4,4'-dicarboxylic acid (one of the monomers (B)), 3-aminophenol (one of the monomers (C)), 6-methyl-3-aminophenol ( 1 type of monomer (C)), 1-amino-7-naphthol (also known as "8-amino-2-naphthol": 1 type of monomer (C)), resorcinol (1 type of monomer (C)), bisphenol fluorene (one of the monomers (C)), biscresol fluorene (one of the monomers (C)), 2,3-dihydroxynaphthalene (one of the monomers (C)), catechol (one of the monomers (C)), BINOL (one type of monomer (C)) is preferred, isophthalic acid, 3-aminophenol, 1-amino-7-naphthol (also known as "8-amino-2-naphthol") is more preferred, 3-aminophenol, 1 -amino-7-naphthol (also known as "8-amino-2-naphthol") is particularly preferred.

In such a linear liquid crystal polymer chain, the content of the compound for forming the flexible structural unit is 20 to 40 mol% ( more preferably 22 to 38 mol %, still more preferably 24 to 36 mol %). If the content of such a compound for forming a flexible structural unit is less than the lower limit, solvent solubility is reduced. It becomes difficult to plan

Thus, since the content of the compound for forming the flexible structural unit is 20 to 40 mol% with respect to the total molar amount of the monomers (A) to (C), the linear liquid crystal polymer chain contains 20 to 40 mol % of monomer units (structural units) derived from the flexible structural unit-forming compound relative to the total amount of monomer units forming the liquid crystal polymer chain. As a result, the shape of the liquid crystal polymer chain is not straight, but rather a bent line that is moderately bent. This makes it possible to dissolve in a solvent and achieve a low dielectric loss tangent while exhibiting liquid crystallinity. becomes.

Further, in the linear liquid crystal polymer chain composed of such monomers (A) to (C), the monomer (A) is 4-hydroxybenzoic acid, 4-(4-hydroxyphenyl)benzoic acid, and At least one selected from the group consisting of 2-hydroxy-6-naphthoic acid,
The monomer (B) is at least one selected from the group consisting of 2,6-naphthalenedicarboxylic acid, isophthalic acid, terephthalic acid, 4,4'-biphenyldicarboxylic acid and diphenyl ether-4,4'-dicarboxylic acid. can be,
The monomer (C) is 3-aminophenol, 4-aminophenol, 1-amino-7-naphthol, 4,4′-biphenol, bisphenolfluorene, biscresolfluorene, 1,1′-bi-2-naphthol, At least one selected from the group consisting of methylhydroquinone, phenylhydroquinone, and 6-methyl-3-aminophenol,
At least one of the monomer (B) and the monomer (C) contains a compound for forming a flexible structural unit, and
The compound for forming the flexible structural unit includes isophthalic acid, diphenyl ether-4,4′-dicarboxylic acid, 3-aminophenol, 6-methyl-3-aminophenol, 1-amino-7-naphthol, bisphenolfluorene, bis It is preferably at least one selected from the group consisting of cresol fluorene and 1,1'-bi-2-naphthol. Further, among the linear liquid crystal polymer chains composed of such monomers (A) to (C), linear liquid crystal polymer chains formed by combining monomers as exemplified in the following (1) to (12) Liquid crystal polymer chains are more preferred.
(Examples of suitable combinations of monomers (A) to (C))
(1) 2-hydroxy-6-naphthoic acid/2,6-naphthalenedicarboxylic acid/3-aminophenol (2) 4-hydroxybenzoic acid/2,6-naphthalenedicarboxylic acid/3-aminophenol (3) 2- Hydroxy-6-naphthoic acid/isophthalic acid/4-aminophenol (4) 2-hydroxy-6-naphthoic acid/isophthalic acid/3-aminophenol (5) 2-hydroxy-6-naphthoic acid/2,6-naphthalene Dicarboxylic acid/1-amino-7-naphthol (6) 2-hydroxy-6-naphthoic acid/2,6-naphthalenedicarboxylic acid/bisphenol fluorene (7) 2-hydroxy-6-naphthoic acid/2,6-naphthalenedicarboxylic acid Acid/biscresol fluorene (8) 2-hydroxy-6-naphthoic acid/2,6-naphthalenedicarboxylic acid/BINOL
(9) 2-hydroxy-6-naphthoic acid/isophthalic acid/1-amino-7-naphthol (10) 4-hydroxybenzoic acid/2,6-naphthalene dicarboxylic acid/1-amino-7-naphthol (11) 2 -hydroxy-6-naphthoic acid/terephthalic acid/1-amino-7-naphthol (12) 2-hydroxy-6-naphthoic acid/terephthalic acid/3-aminophenol (13) 2-hydroxy-6-naphthoic acid/isophthalic acid/methylhydroquinone (14) 2-hydroxy-6-naphthoic acid/isophthalic acid/phenylhydroquinone (15) 2-hydroxy-6-naphthoic acid/diphenylether-4,4'-dicarboxylic acid/methylhydroquinone (16) 2- Hydroxy-6-naphthoic acid/2,6-naphthalenedicarboxylic acid/6-methyl-3-aminophenol (17) 2-hydroxy-6-naphthoic acid/isophthalic acid/4,4'-biphenyldicarboxylic acid/methylhydroquinone ( 18) 2-hydroxy-6-naphthoic acid/isophthalic acid/4,4'-biphenyldicarboxylic acid/methylhydroquinone/4,4'-biphenol (19) 2-hydroxy-6-naphthoic acid/isophthalic acid/methylhydroquinone/ 4,4'-biphenol (20) 2-hydroxy-6-naphthoic acid/diphenyl ether-4,4'-dicarboxylic acid/4,4'-biphenyldicarboxylic acid/methylhydroquinone (21) 2-hydroxy-6-naphthoic acid /diphenyl ether-4,4'-dicarboxylic acid/4,4'-biphenyldicarboxylic acid/methyl hydroquinone/4,4'-biphenol (22) 2-hydroxy-6-naphthoic acid/diphenyl ether-4,4'-dicarboxylic acid /methylhydroquinone/4,4'-biphenol.

<Regarding the structure in which the linear liquid crystal polymer chain is bonded via the monomer (D)>
The liquid crystal polyester (I) is formed by bonding the linear liquid crystal polymer chains via the monomer (D). In such a liquid crystal polyester (I), the content of the monomer (D) is 0.01 to 10 mol per 100 mol of the total molar amount of the monomers (A) to (C). That is, in such a liquid crystal polyester (I), when the total molar amount of the monomers (A) to (C) is converted to 100 mol, the total molar amount of the monomers (A) to (C) is 100 mol. The monomer (D) is contained at a ratio of 0.01 to 10 mol with respect to (converted value). If the content of the monomer (D) is less than the lower limit, it will be difficult to achieve a low dielectric loss tangent, and the pot life (usable time) of the resin solution will be reduced. , solid content remains when dissolved in a solvent, and a high degree of solubility cannot be obtained.

Further, in the liquid crystal polyester (I), the content ratio of the monomer (D) (the content ratio of structural units derived from the monomer (D)) is relative to the total molar amount of 100 mol of the monomers (A) to (C). Although it is necessary to set the ratio to 0.01 to 10 mol, when the content ratio of the monomer (D) is smaller (for example, the total molar amount of the monomers (A) to (C) is 100 mol, the monomer When the content ratio of (D) is about 5 mol or less), a so-called dendrimer (hyperbranched polymer or star A multi-branched structure such as burst polymer), that is, the central molecule (core) is derived from the monomer (D), and the linear liquid crystal polymer chain is bound to the core It is considered possible to have a multi-branched structure that serves as a side chain. Since the monomer (D) is a polyfunctional monomer, it can form a multi-branched structure with the monomer (D) as the central molecule, depending on the number of functional groups. Further, when the content ratio of the monomer (D) is relatively large within the range of 0.01 to 10 mol with respect to the total molar amount of 100 mol of the monomers (A) to (C) (for example, the monomer (A ) to (C) at a content ratio of about 6 mol or more per 100 mol of the total molar amount of (C)), it is considered that a network-like structure can be formed at least partially. In addition, when the content ratio of the monomer (D) in the liquid crystal polyester is set to an amount (percentage) exceeding 10 mol with respect to the total molar amount of 100 mol (converted value) of the monomers (A) to (C), The present inventors presume that the formed network structure becomes dense, and as a result, the solubility in the solvent does not become high.

Here, from the viewpoint of lowering the dielectric loss tangent value and further improving the solubility, the content ratio of the monomer (D) with respect to the total molar amount of 100 mol of the monomers (A) to (C) is 0. .1 to 5 mol, more preferably 0.5 to 4 mol. On the other hand, from the viewpoint of further improving the toughness of the resin and the solution stability of the resin solution at the stage of low degree of polymerization, the content ratio of the monomer (D) with respect to the total molar amount of 100 mol of the monomers (A) to (C) is preferably 6 to 10 mol, more preferably 7 to 9 mol.

Further, in such a liquid crystal polyester, the total amount of the monomers (A) to (C) constituting the linear liquid crystal polymer chain is 90.0 to 99 with respect to the total amount of the monomers (A) to (D). It is preferably 0.9 mol %, more preferably 93.0 to 99.4 mol %. When the total amount of such monomers (A) to (C) (the content of the linear liquid crystal polymer chain) is within the above range, the development of liquid crystallinity, low dielectric loss tangent, and solvent solubility can be achieved. It tends to be more well-balanced.

The liquid crystal polyester (I) has liquid crystallinity (optical anisotropy) due to the linear liquid crystal polymer chain, and such liquid crystallinity can be confirmed by observation with a polarizing microscope. Here, the linear liquid crystal polymer chain has liquid crystallinity (optical anisotropy) depending on the type of monomer used and the content of the compound for forming the flexible structural unit. When the obtained liquid crystalline polyester is determined to have liquid crystallinity, it can be determined that the linear polymer chain composed of the monomers (A) to (C) also has liquid crystallinity.

Although the method for producing such a liquid crystal polyester (I) is not particularly limited, for example, it contains the monomers (A) to (D), and the At least one of them contains a compound for forming a flexible structural unit, and the content of the compound for forming a flexible structural unit is 20 to 20 with respect to the total molar amount of the monomers (A) to (C). Polycondensation of a raw material mixture having a content of 40 mol% and a content ratio of the monomer (D) in a ratio of 0.1 to 10 mol per 100 mol of the total molar amount of the monomers (A) to (C). A method of obtaining a liquid crystal polyester (I) in which a linear liquid crystal polymer chain composed of the monomers (A) to (C) is bonded via the monomer (D) by allowing the In some cases, a method called “manufacturing method (I)”) can be employed.

The raw material mixture used in method (I) contains the monomers (A) to (D). In such a raw material mixture, at least one of the monomer (B) and the monomer (C) contains a compound for forming a flexible structural unit. The form of such a raw material mixture is not particularly limited, and the monomer (B) containing the compound for forming the flexible structural unit may be combined with another monomer, or the compound for forming the flexible structural unit may be combined. The monomer (C) containing may be combined with other monomers, and furthermore, the monomer (B) containing the compound for forming the flexible structural unit and the monomer (C) containing the compound for forming the flexible structural unit A combination with other monomers may also be used.

In such a raw material mixture, the content of the compound for forming the flexible structural unit is 20 to 40 mol% (more preferably 22 to 38 mol %, more preferably 24 to 36 mol %). If the content of such a compound for forming a flexible structural unit is less than the lower limit, solvent solubility is reduced. It becomes difficult to plan

Furthermore, in such a raw material mixture, the content ratio of the monomer (D) is 0.01 to 10 mol per 100 mol of the total molar amount of the monomers (A) to (C). If the content of the monomer (D) is less than the above lower limit, polycondensation of the raw material mixture will not form a multi-branched structural portion and the desired dielectric loss tangent will not be obtained. On the other hand, when the content of the monomer (D) exceeds the upper limit, the probability of contact between the monomer (D) and the monomers (A) to (C) increases when the raw material mixture is polycondensed. A dense network structure is formed and the solubility in solvents is reduced.

In addition, the content ratio of the monomer (D) is the total moles of the monomers (A) to (C) because the liquid crystal appearance, the low dielectric loss tangent, and the solvent solubility are well-balanced. More preferably, the ratio is 0.1 to 5 mol (more preferably 0.5 to 4 mol) per 100 mol. In this way, when the content ratio of the monomer (D) in the raw material mixture is set to a lower value such that the total molar amount of the monomers (A) to (C) is 100 mol or less, 5 mol or less Since the probability of contact between the monomer (D) and other monomers is reduced, a structure in which a linear liquid crystalline polyester chain composed of monomers (A) to (C) is bonded through the core monomer (D). can be made into a so-called dendrimer type structure. On the other hand, from the viewpoint of further improving the toughness of the resin and the solution stability (pot life) of the resin solution at the stage of low degree of polymerization, the monomer (D ) is preferably 6 to 10 mol, more preferably 7 to 9 mol.

In addition, the content of the monomer (A), the content of the monomer (B), and the content of the monomer (C) in the linear liquid crystal polymer chain in the obtained liquid crystal polyester are each within the above-mentioned suitable ranges. Therefore, in the raw material mixture, the content of the monomer (A) with respect to the total molar amount of the monomers (A) to (C) is 20 to 70 mol% (more preferably 30 to 60 mol%), and the content of the monomer (B) with respect to the total molar amount of the monomers (A) to (C) is 10 to 50 mol% (more preferably 20 to 40 mol%). It is preferable to set the content of the monomer (C) to 10 to 50 mol% (more preferably 20 to 40 mol%) with respect to the total molar amount of the monomers (A) to (C). Further, the total amount of the monomers (B) to (C) with respect to 100 parts by mass of the monomer (A) is 50 to 200 parts by mass (more preferably 55 to 190 parts by mass, more preferably 60 to 180 parts by mass). preferable.

Furthermore, the raw material mixture preferably further contains an acid anhydride from the viewpoint of an industrial production method (decarboxylation polymerization). Suitable acid anhydrides include acetic anhydride, propionic anhydride, butyric anhydride, and isobutyric anhydride. is more preferred. The content of such an acid anhydride is 1.00 to 1.20 molar equivalents (more preferably 1.01 to 1.10 molar equivalents).

In addition, in such a raw material mixture, if necessary, catalysts, other monomers, condensing agents, known additive components that can be used for polyester polycondensation such as azeotropic solvents, oligomers, polymers, etc. You may let

As such a catalyst, conventionally known polyester polymerization catalysts can be used, and examples thereof include magnesium acetate, stannous acetate, tetrabutyl titanate, lead acetate, sodium acetate, potassium acetate, and antimony trioxide. metal salt catalysts such as N-methylimidazole; organic compound catalysts such as nitrogen-containing heterocyclic compounds such as N-methylimidazole; The amount of such a catalyst to be used is not particularly limited, but is preferably 0.0001 to 0.1 parts by weight with respect to 100 parts by weight of the total amount of monomers.

Further, as a method of polycondensing (reacting) the raw material mixture, the functional groups (hydroxy group, carboxy group, amino group, etc.) possessed by each of the monomers (A) to (D) are reacted with each other to polycondense. For example, a known polycondensation method capable of forming an ester bond and/or an amide bond can be used as appropriate.

In addition, when the raw material mixture is polycondensed (reacted), it is possible to further improve the reaction efficiency and product yield while reducing the number of steps. Polycondensation is preferred. In addition, the reaction conditions for such polycondensation are not particularly limited and can be appropriately selected from known conditions used for forming a liquid crystalline polyester depending on the type of monomer used. It is preferable to carry out polycondensation by melt polymerization by reacting the raw material mixture for 0.1 to 100 hours under temperature conditions of 0 to 400° C. (more preferably 100 to 380° C.).

In such polycondensation, from the viewpoint of improving the degree of polymerization and physical properties, the raw material mixture is reacted under a first temperature condition of 100 to 400 ° C. (more preferably 120 to 380 ° C.) to obtain a polymer with a low degree of polymerization. After forming the (prepolymer), the raw material mixture is further reacted under a second temperature condition of 150 to 400 ° C. (more preferably 160 to 380 ° C.) to polycondense by melt polymerization or solid state polymerization. It is preferable to adopt The reaction time under such first temperature conditions is preferably 0.1 to 50 hours (more preferably 0.5 to 30 hours), and the reaction time under the second temperature conditions is 0.1 hour. It is preferably 5 to 50 hours (more preferably 1.0 to 30 hours). By setting the first and second temperature conditions and each reaction time within the above ranges, it is possible to improve the degree of polymerization and physical properties.

In addition, after obtaining a prepolymer by melt polymerization or the like in which the reaction is performed under the first temperature condition, the prepolymer is cooled and solidified, and then pulverized into powder or flakes, followed by a known solid phase polymerization method. (For example, a method such as heat-treating a prepolymer resin in an inert atmosphere such as nitrogen or under vacuum at a temperature range of 100 to 400° C. for 1 to 30 hours) may be used for polycondensation.

In addition, the polymerization reaction apparatus that can be used when performing such polycondensation (preferably melt polymerization) is not particularly limited, and for example, a known reaction apparatus that is used for reactions of high-viscosity fluids may be used as appropriate. . Such reactors include, for example, an anchor type, multi-stage type, spiral band type, spiral shaft type, etc., or a stirred tank polymerization reactor having a stirring device with stirring blades of various shapes modified from these, or Mixing devices such as kneaders, roll mills, and Banbury mixers used for kneading resins can be used.

In this way, by polycondensing the raw material mixture, a liquid crystal polyester (I ) can be obtained.

The liquid crystalline polyester (I) suitable for the present invention has been described above, but the liquid crystalline polyester according to the present invention may be any as long as it is soluble in a solvent, and its structure is not limited to the above structure. Further, the liquid crystal polyester (preferably liquid crystal polyester (I)) according to the present invention preferably has a number average molecular weight (Mn) of 10,000 to 1,000,000, more preferably 50,000 to 500,000. It preferably has a molecular weight (Mw) of 20,000 to 2,000,000, more preferably 100,000 to 1,000,000. Further, in the liquid crystal polyester, the ratio (Mw/Mn) between the number average molecular weight (Mn) and the weight average molecular weight (Mw) is in the range of 1.0 to 15.0 (more preferably 2.0 to 10.0). is preferred. When such Mn and Mw are within the above ranges, it tends to be possible to form a more uniform and stronger film when formed. Such molecular weights can be measured by GPC (gel permeation chromatography) analysis. As a specific measuring method, the same method as that employed in the method for measuring the number average molecular weight of the liquid crystalline polyester obtained in the examples described later can be employed.

Further, when the liquid crystalline polyester according to the present invention has a melting point of 100 to 400° C., it may exhibit an optical anisotropic melting phase after thermally melting at such a temperature. Such an optically anisotropic molten phase state can be observed with a polarizing microscope.

Moreover, the liquid crystalline polyester according to the present invention is soluble in a solvent (solvent). In the present invention, when 4 g of liquid crystalline polyester is mixed with 16 g of N-methyl-2-pyrrolidone (NMP) and heated at 100° C. for 2 hours, the solid content of the polyester cannot be visually confirmed. In that case, the liquid crystalline polyester is judged to be soluble in the solvent (soluble in the solvent). Thus, since the liquid crystalline polyester according to the present invention is soluble in solvents, it can be dissolved in various solvents and used as a resin solution, thereby further improving workability during molding. It is also possible to let

Next, a polyester layer made of liquid crystalline polyester soluble in such a solvent will be described.

In the present invention, the polyester layer may be laminated on at least one surface of the polyimide film. Since the polyimide constituting the polyimide film has a highly polar (water-absorbing) imide skeleton, when it is used alone, it absorbs moisture etc. in the atmospheric gas under the usage environment, and the relative dielectric constant There is a demerit that the dielectric loss tangent becomes large. On the other hand, the polyester layer has relatively low water absorption due to the structure of the liquid crystalline polyester that constitutes the layer. In the laminate of the present invention, since the polyester layer is formed on at least one surface of such a polyimide film, it is possible to further reduce the intrusion of moisture from the surface side where the polyester layer is formed. It is possible. Thus, the laminate of the present invention can further reduce water absorption during use due to its structure, and can maintain a low dielectric constant and dielectric loss tangent for a long period of time. . Moreover, regarding the laminate of the present invention, it is preferable that the polyester layer is laminated on both sides of the polyimide film from the viewpoint of further suppressing water absorption.

The thickness of such a polyester layer is not limited, but the laminate can be used for high frequency flexible printed circuit boards, high frequency flexible copper clad laminates, high frequency flexible thin multilayer boards, high frequency components, Wi-Fi (registered). From the viewpoint of application to applications such as RF lines for trademark), Wi-Fi (registered trademark) antennas, millimeter wave band antennas, digital lines, millimeter wave radar parts, etc., 0.1 μm to 500 μm (more preferably, 1 μm to 200 μm).

Moreover, such a polyester layer may be a layer made of a liquid crystalline polyester soluble in the solvent, and such a layer may contain an additive component together with the liquid crystalline polyester. Such additive components include antioxidants, ultraviolet absorbers/hindered amine light stabilizers, nucleating agents/clarifying agents, inorganic fillers (glass fibers, hollow glass spheres, talc, mica, alumina, titania, silica, etc.). , heavy metal deactivators/additives for filler-filled plastics, flame retardants, processability improvers/lubricants/water-dispersible stabilizers, permanent antistatic agents, toughness improvers, surfactants, carbon fibers, and the like.

In addition, the method for producing the laminate of the present invention is not particularly limited. It is possible to manufacture to As a method that can be suitably used as a method for producing such a laminate, for example, the resin solution (varnish) is applied to at least one surface of the polyimide film to form a coating film, and such coating A method of manufacturing by curing a film can be exemplified. A method for producing a laminate using such a resin solution will be briefly described below.

The resin solution (varnish) comprises liquid crystal polyester soluble in the solvent and a solvent (solvent). The solvent (solvent) used for such a resin solution (varnish) is not particularly limited as long as it is capable of dissolving the liquid crystalline polyester. For example, halogen solvents (1-chlorobutane, chlorobenzene, 1,1-dichloroethane, 1,2-dichloroethane, chloroform, 1,1,2,2-tetrachloroethane, etc.), ether solvents (diethyl ether, tetrahydrofuran, 1, 4-dioxane, etc.), ketone solvents (acetone, cyclohexanone, etc.), ester solvents (ethyl acetate, etc.), lactone solvents (γ-butyrolactone, etc.), carbonate solvents (ethylene carbonate, propylene carbonate, etc.), amine solvents (triethylamine, pyridine, etc.), nitrile solvents (benzonitrile, acetonitrile, succinonitrile, etc.), amide solvents (N,N'-dimethylformamide, N,N'-dimethylacetamide, tetramethylurea, 1,3- dimethyl-2-imidazolidinone, N-methyl-2-pyrrolidone (NMP), etc.), nitro solvents (nitromethane, nitrobenzene, etc.), sulfide solvents (dimethyl sulfoxide, sulfolane, etc.), phosphoric acid solvents (hexamethylphosphorus acid amide, tri-n-butyl phosphate, etc.). Among such solvents, from the viewpoint of obtaining higher solubility, N,N'-dimethylformamide, N,N'-dimethylacetamide, tetramethylurea, 1,3-dimethyl-2-imidazolidinone, Alternatively, N-methyl-2-pyrrolidone (NMP) is more preferred, and N-methyl-2-pyrrolidone (NMP) is particularly preferred. Such solvents may be used singly or in combination of two or more.

The content of the liquid crystalline polyester in such a resin solution (varnish) is not particularly limited, but is preferably 0.1 to 80% by mass (more preferably 1 to 50% by mass). By setting such a content within the above range, it can be more suitably used as a varnish for producing a resin film (such a resin film may be used as a resin layer laminated on a substrate) or the like. From the viewpoint of using such a resin solution (varnish) as a solution for forming a film, it is preferable that the mass of the solvent is 2 to 100 times the mass of the liquid crystalline polyester. In addition, such a resin solution contains, for example, the above-mentioned additive components (antioxidants, ultraviolet absorbers, hindered amine light stabilizers, etc.) as appropriate, depending on the design of the intended polyester layer and the use of the laminate. You may let

The method for applying such a resin solution (varnish) to at least one surface of the polyimide film is not particularly limited, but examples include spin coating, roller coating, spray coating, curtain coating, and dip coating. , slot coating method, dropping method, gravure printing method, screen printing method, letterpress printing method, die coating method, curtain coating method, ink jet method and the like can be appropriately employed. For example, when the dip coating method is employed and the polyimide film is immersed in the resin solution, the resin solution is applied to both sides of the polyimide film to form a coating film on both sides of the polyimide film. The liquid crystalline polyester can be easily formed on both sides.

Further, the resin solution (varnish) is applied to at least one surface of the polyimide film to form a coat film, and then the coat film is cured to obtain a laminate in which liquid crystal polyester layers are laminated. can. The method for curing such a coating film is not particularly limited, but for example, a method of curing by heating the coating film (coating film) at a temperature of about 100 to 400 ° C. for 0.1 to 50 hours (heating curing method) may be employed. Moreover, a step of removing the solvent from the coating film (coating film) may be performed before heat curing by such a method. Such a solvent removal step is not particularly limited, and can be carried out by appropriately setting the conditions according to the type of solvent (for example, the coating film is heated at a temperature of 20 to 200° C. for 0.1 to 50 hours. You may adopt the method of standing still). In the solvent removal step, it is preferable to adopt a method of heating while flowing an inert gas (inert gas) or heating while reducing pressure. It is preferable to employ a temperature above the boiling point.

In addition, such a laminate of the present invention may further have other layers or the like depending on its use. Such other layers are not particularly limited, and include metal layers such as copper foil and aluminum foil, semiconductor layers such as polysilicon, amorphous silicon, LTPS, LTPO, and IGZO, transparent conductive film layers such as ITO, glass layers, and the like. be done.

Further, the use of the laminate of the present invention is not particularly limited. RF line, Wi-Fi (registered trademark) antenna, millimeter wave band antenna, digital line, parts for millimeter wave radar, flexible liquid crystal display substrate, flexible organic EL display substrate, flexible micro LED substrate, flexible quantum dot display substrate, organic EL Lighting substrates, flexible solar cell substrates, and the like can be mentioned.

EXAMPLES The present invention will be described in more detail below based on examples and comparative examples, but the present invention is not limited to the following examples.

[Regarding the raw material compounds used in each example etc.]
Abbreviations and the like of compounds (monomers) used in Examples and the like are shown below. In the descriptions (including tables) of Examples and the like below, the following abbreviations are used to represent compounds.

<Monomer (A): Bifunctional Aromatic Hydroxycarboxylic Acid>
・ 2,6-HNA: 2-hydroxy-6-naphthoic acid (manufactured by Ueno Pharmaceutical Co., Ltd.)
<Monomer (B): Bifunctional Aromatic Dicarboxylic Acid>
・ 2,6-NDCA: 2,6-naphthalene dicarboxylic acid (manufactured by Ueno Pharmaceutical Co., Ltd.)
・ IPA: isophthalic acid (manufactured by Mitsubishi Gas Chemical Company, Inc.)
· DCDPE: diphenyl ether-4,4'-dicarboxylic acid (manufactured by Tokyo Chemical Industry Co., Ltd.)
<Monomer (C): Bifunctional Aromatic Hydroxamine>
・ 3-AP: 3-aminophenol (manufactured by Aldrich)
・ 4-AP: 4-aminophenol (manufactured by Aldrich)
1,7-ANL: 1-amino-7-naphthol (manufactured by Aldrich: 8-amino-2-naphthol)
・ MHQ: Methyl hydroquinone (manufactured by Seiko Chemical Co., Ltd.)
<Monomer (D): polyfunctional (tetrafunctional) aromatic compound>
・ 2,5-DHTPA: 2,5-dihydroxyterephthalic acid (manufactured by Tokyo Chemical Industry Co., Ltd.)
・ 1,5-DONDC: 1,5-dihydroxynaphthalene-2,6-dicarboxylic acid (manufactured by Sugai Chemical Industry Co., Ltd.)
・ 1,3,5-BTCA: 1,3,5-benzenetricarboxylic acid (manufactured by Tokyo Chemical Industry Co., Ltd.)
・ 5H-IPA: 5-hydroxyisophthalic acid (manufactured by Tokyo Chemical Industry Co., Ltd.)
・ 3,5-DHBA: 3,5-dihydroxybenzoic acid (manufactured by Tokyo Chemical Industry Co., Ltd.)
・ 1,3,5-BTOH: 1,3,5-trihydroxybenzene (anhydrous, manufactured by Tokyo Chemical Industry Co., Ltd.)
"IPA", "3-AP", "1,7-ANL" and "DCDPE" used as the monomer (B) or (C) are all compounds for forming flexible structural units.

[Method for evaluating properties of polyester prepared in each example]
Regarding the polyester used for producing the laminate in each example, its structure, properties, etc. were evaluated as follows.

<Evaluation of Structure of Liquid Crystal Polyester>
For the liquid crystal polyester obtained in each example, a Fourier transform infrared (FT-IR) spectrophotometer manufactured by Thermo SCIENTIFIC (trade name "NICOLET is10") and a trade name "MicromATR vision" manufactured by Czitek were used as measuring devices. was used to characterize the structure by making IR measurements under conditions of total reflection (ATR). Since the absorption spectrum near 1700 cm ^-1 in IR measurement is derived from the C=O stretching of esters and amides, the absorption spectrum near 1700 cm ^-1 in IR measurement confirms the existence of C=O stretching of the ester. The polyester was evaluated to have been formed through the progress of esterification or the like due to the reaction of the monomers.

<Evaluation of liquid crystallinity of liquid crystalline polyester>
The presence or absence of liquid crystallinity was evaluated by observing the liquid crystalline polyester obtained in each example with a polarizing microscope. That is, using a polarizing microscope manufactured by Olympus (trade name: "BHS-751-P-100") and a heating stage system (HS82) manufactured by Mettler Toledo, the liquid crystal polyester is heated and melted on the microscope heating stage. After heating, the liquid crystallinity was confirmed by observing the presence or absence of optical anisotropy.

<Measurement of number average molecular weight of liquid crystalline polyester>
The number average molecular weight (Mn) was determined by performing GPC (gel permeation chromatography) measurement on the liquid crystalline polyester obtained in each example. That is, an NMP solution of liquid crystalline polyester (content of liquid crystalline polyester: 20 wt%) was prepared, and one drop (about 15 mg) was added to 1.0 mL of GPC eluent (1.0 L of N,N-dimethylacetamide). solution to which 10 mmol of lithium chloride was added), and TOSOH EcoSEC HLC-8320GPC (GPC column: TOSOH TSKgel super AW 2500 × 2 + TOSOH TSKgel super AW 3000 × 1 + TOSOH TSKgel super AW 4000 × 1 + TOSOH TSKgel guardcolumn super AW-L x 1) was used, and the analysis was performed under the conditions of a flow rate of 0.5 ml/min. Analysis was performed using both a refractometer (RI) and an ultraviolet analyzer (UV: 275 nm) as detectors, and the number average molecular weight (Mn) was obtained from the RI data.

<Evaluation of Solubility of Liquid Crystal Polyester>
4.0 g of the liquid crystal polyester obtained in each example was mixed with 16.0 g of N-methyl-2-pyrrolidone (NMP), the resulting mixture was heated at 100 ° C. for 2 hours, and then the mixture Visually confirm whether or not the solid content of the polyester remains inside, and if there is no solid content remaining, it is evaluated as having solvent solubility. It was evaluated that there is no Such evaluation was also performed during the process of preparing the resin solution.

<Measurement of Melting Point of Liquid Crystal Polyester>
The melting point of the liquid crystalline polyester obtained in each example was determined by DSC measurement. That is, the melting point was measured with a differential scanning calorimeter (DSC-7020) manufactured by Seiko SII in accordance with the test methods of ISO11357 and ASTM D3418. In this measurement, the polymer was completely melted by heating from room temperature to 300 to 380° C. at a heating rate of 10° C./min under a nitrogen stream (200 mL/min), and then at a rate of 10° C./min. The apex of the endothermic peak obtained when the temperature was lowered to 30° C. and then raised to 360° C. at a rate of 10° C./min was determined as the melting point (Tm).

(Example 1)
<Preparation process of liquid crystalline polyester>
2,6-HNA (0.205 mol, 38.59 g), 2,6-NDCA (0.137 mol, 29.56 g), 3-AP (0.137 mol, 14.92 g) were placed in a 500 ml separable flask. , 2,5-DHTPA (0.003 mol, 0.68 g), acetic anhydride (0.482 mol, 49.55 g) were added. Next, the obtained raw material mixture was heated in a separable flask at 200° C. for 1 hour to cause polycondensation, then heated to 330° C. and held at 330° C. for 30 minutes to further polycondense. After the polycondensation reaction of the raw material mixture in this way, the molten resin (liquid crystal polyester) is extracted from the separable flask and cooled to room temperature (25 ° C.) to form a massive liquid crystal polyester (number average molecular weight ( GPC): 115240, mp 319°C).

From the results of IR measurement of the obtained liquid crystalline polyester, the obtained resin was found to be a polyester resin because the C=O stretching vibration of the aromatic polyester was confirmed at 1726 cm ^-1 (it should be noted that , the C═O stretching vibration of aromatic amides was identified at 1672 cm ⁻¹ ). In addition, it was also found that the obtained resin had a dendrimer-type structure (dendrimer-type liquid crystalline polyester) instead of a network structure, because the GPC measurement results showed a single peak in the spectrum. Furthermore, it was confirmed that the obtained liquid crystalline polyester exhibited liquid crystallinity (it was thermotropic liquid crystal), and it was also found that in the dendrimer-type liquid crystalline polyester, the branched polymer chain portion has liquid crystallinity. Table 1 shows the properties of the obtained polyester.

<Resin solution preparation process>
After crushing the bulky liquid crystalline polyester (dendrimer-type liquid crystalline polyester) obtained as described above with a mallet, NMP (16.0 g) was added to the liquid crystalline polyester powder (4.0 g), followed by heating at 100° C. for 2 hours. A resin solution was obtained by dissolving by heating for a period of time. In addition, solid content was not visually confirmed in such a resin solution. Since the liquid crystalline polyester was completely dissolved in NMP as described above, it was found that the liquid crystalline polyester obtained as described above has solvent solubility.

<Laminate preparation process>
The resin solution obtained in the previous section is applied to both sides of a polyimide film (trade name “UPILEX-25S” manufactured by Ube Industries, length: 80 mm, width 3 mm, thickness 25 μm, film punched with dumbbell cutter of Dumbbell Co., Ltd.) , Dip coating so that the total thickness of the coating film on both sides after heating is 22 μm (the thickness of the coating film on one side is 11 μm, and the total thickness of the laminate is 47 μm), and the coating film is coated on the polyimide film. formed. After that, the polyimide film having the coating film formed thereon was placed in an inert oven (nitrogen flow rate: 5 L/min), heated under a nitrogen atmosphere at a temperature of 80°C for 0.5 hours, and heated at a temperature of 240°C for 60 minutes. After heating for 1 minute to bake the coating film, the film was cooled to 80° C. in a nitrogen atmosphere to obtain a laminate in which thin films made of polyester (polyester layers) were laminated on both sides of the polyimide film.

(Examples 2 to 15)
The types of monomers (B) to (D) are changed to those shown in Table 1 or Table 2, respectively, and the amounts (molar amounts) of monomers (A) to (D) used are shown in Table 1 or Table 2, respectively. The thickness of the coating film is changed so as to satisfy the conditions of the molar ratio, and furthermore, in the preparation process of the laminate, the thickness of the coating film is such that the total thickness of the laminate becomes the thickness shown in Table 1 or Table 2 at the time of dip coating. Except for changing the "liquid crystal polyester preparation process", "resin solution preparation process" and "laminate preparation process" adopted in Example 1, adopting the same steps as the liquid crystal polyester After preparing , a resin solution was prepared, and then a laminate was prepared. As is clear from Tables 1 and 2, in Examples 1 to 12 and 14 to 15, the molar ratio of monomers (A) to (C) (monomer (A):monomer (B): Each monomer was utilized so that the ratio of monomer (C)) was 1.5:1.0:1.0, and in Example 13, the molar ratio of monomers (A) to (C) (monomer (A ) : Monomer (B) : Monomer (C) were used so that the ratio was 2.0: 1.0: 1.0.In Example 15, Monomer (D) was not used. A liquid crystalline polyester was prepared.The characteristics of the polyester obtained in each example (existence of liquid crystallinity and solvent solubility, etc.) are shown in Table 1 or Table 2.In the same manner as in Example 1, IR measurement, etc. As a result of evaluating the characteristics etc., it was confirmed that all the polymers obtained in the preparation process of the liquid crystalline polyester used in Examples 2 to 15 were polyesters and liquid crystalline (thermotropic liquid crystal It was confirmed that the liquid crystal polyesters obtained in Examples 2 to 15 were completely dissolved in NMP without visually confirming the solid content in the resin solution preparation process. Therefore, it was found that all of the liquid crystalline polyesters obtained in the liquid crystalline polyester preparation steps employed in Examples 2 to 15 have solvent solubility.

As shown in Tables 1 and 2, in Examples 1 to 14, regarding the monomers used for the preparation of the liquid crystalline polyester constituting the polyester layer, the "flexible structural unit The content of the "compound for formation" was 29 mol% (Examples 1 to 12 and 14) or 25 mol% (Example 13), and the content of the monomer (D) was the monomers (A) to (C ) was 0.7 mol, 1.0 mol or 7 mol per 100 mol of the total amount of

(Comparative example 1)
A commercially available polyimide film (trade name “UPILEX-25S” manufactured by Ube Industries, Ltd., length: 80 mm, width 3 mm, thickness 25 μm, film punched with a dumbbell cutter of Dumbbell Co., Ltd.) was used as a film for comparison. did.

[Evaluation of properties of the laminates obtained in Examples 1 to 15 and the polyimide film used as Comparative Example 1]
<Measurement method of dielectric loss tangent (Df) and dielectric constant (Dk)>
Using the laminates obtained in Examples 1 to 15 and the polyimide film of Comparative Example 1 as sample pieces, a cavity resonator manufactured by AET Co., Ltd. was analyzed with a spectrum network analyzer MS46122B manufactured by Anritsu Co., Ltd. Using a measuring device connected to , under the conditions of 25° C., 50% relative humidity, and 10 GHz, the cavity resonator method was adopted to measure the dielectric constant and the dielectric loss tangent. In the measurement, the sample piece was dried at 100°C for 2 hours, then left in a constant temperature and humidity chamber at 25°C and 50% humidity for 1 day and night (24 hours) before measurement. used. The results obtained are shown in Tables 1 and 2.

As is clear from the results shown in Tables 1 and 2, in the laminates (Examples 1 to 15) provided with polyester layers (PEs layers) made of solvent-soluble liquid crystal polyester on both sides of the polyimide film, Also, compared with the case of using the polyimide film alone (Comparative Example 1), it became possible to make the dielectric constant and the dielectric loss tangent lower values. In addition, when comparing Example 3 and Example 15, which have the same monomer configuration except for the use of the monomer (D), by using the monomer (D), the relative dielectric constant and dielectric loss tangent are further reduced. It was found that it is possible to From these results, the laminates obtained in Examples 1 to 14, which utilize a specific amount of monomer (D) together with monomers (A) to (C), have lower dielectric constants and dielectric loss tangents. It was also found that it is possible to set the value

<Evaluation test for water absorption>
Regarding Example 1, Example 13, and Example 14, the resin solution prepared in each example was used to prepare a liquid crystal polyester film in the following manner, and a sample was prepared from the film, and each example The water absorption rate of the liquid crystalline polyester constituting the polyester layer (PEs layer) in the laminate was obtained. In addition, a sample was also prepared from the commercially available polyimide film (manufactured by Ube Industries, Ltd., trade name "UPILEX-25S") used in Comparative Example 1, and the water absorption rate of the polyimide constituting the polyimide film was also obtained for comparison. rice field. Hereinafter, first, the preparation process of the liquid crystalline polyester film will be explained, and then the method for measuring the water absorption will be explained.

(Preparation process of liquid crystalline polyester film)
Films were prepared in the following manner using the resin solutions obtained in the "resin solution preparation step" of Examples 1, 13 and 14, respectively. That is, first, the resin solution is coated on the surface of a glass substrate [large slide glass (manufactured by Matsunami Glass Industry Co., Ltd., product name "S9213", length: 76 mm, width 52 m, thickness 1.3 mm)] after heating. A coating film was formed on the glass substrate by spin coating so that the thickness of the film was 25 μm. Thereafter, the glass substrate having the coating film formed thereon was placed on a hot plate at 70° C. and allowed to stand still for 0.5 hour to evaporate and remove the solvent from the coating film (solvent removal treatment). After such a solvent removal treatment, the glass substrate with the coating film formed thereon was placed in an inert oven (nitrogen flow rate: 5 L/min), and placed under a nitrogen atmosphere at a temperature of 80°C for 0.5 hours. After heating at 240° C. for 60 minutes, the glass substrate was cooled to 80° C. in a nitrogen atmosphere to obtain polyester-coated glass in which a polyester thin film was coated on the glass substrate. Next, the polyester-coated glass thus obtained was immersed in hot water at 90° C., and the polyester film was peeled off from the glass substrate to obtain a polyester film (length 76 mm, width 52 mm, thickness 25 μm). sized film) was obtained.

(Method for measuring water absorption)
A liquid crystal polyester film (thickness 25 μm) obtained as described above and a commercially available polyimide film (trade name “UPILEX-25S” manufactured by Ube Industries, Ltd., thickness 25 μm) were used, respectively, and cut into 1 cm squares. Each sample was prepared. Next, the obtained samples were each dried in a vacuum oven set at 100° C. for 1 hour, and then precisely weighed to measure the dry mass of each sample. After that, each sample was immersed in distilled water for 24 hours, then the sample was taken out from the distilled water, and the attached water was wiped off with a paper cloth (manufactured by Nippon Paper Crecia Co., Ltd., trade name "Kimwipe (registered trademark)"). By weighing, the mass of each sample at the time of water absorption was measured. Then, for each sample, from the weight at the time of water absorption and the weight at the time of drying, the following formula:
[Water absorption (mass%)] = ([mass at the time of water absorption] - [mass at the time of drying]) / [mass at the time of drying]
(calculated by dividing the difference between the weight of the sample at the time of water absorption and the weight at the time of drying by the weight at the time of drying) to obtain the water absorption.

As a result of such water absorption measurement, the water absorption of the liquid crystalline polyester constituting the polyester layers laminated on both sides of the substrates obtained in Examples 1, 13 and 14 was 1.0. % by mass (Example 1), 0.6% by mass (Example 13), and 0.2% by mass (Example 14), and the water absorption of the polyimide for comparison was 1.5% by mass. From these results, in the laminates (Examples 1, 13 and 14) in which polyester layers are formed on both sides of the polyimide film (base material), the water absorption rate is lower than that when the polyimide film is used as it is. was found to be lower. Therefore, according to the laminate of the present invention (Examples 1 to 15), it is possible to suppress the increase in the dielectric constant and dielectric loss tangent due to the influence of moisture at a higher level. It was also found that the relative permittivity and dielectric loss tangent can be made lower values than when they are used as they are.

INDUSTRIAL APPLICABILITY As described above, according to the present invention, it is possible to provide a laminate capable of exhibiting a lower dielectric constant and dielectric loss tangent than when a polyimide film is used alone. . Therefore, the laminate of the present invention is particularly useful for high-frequency flexible printed circuit boards, high-frequency flexible copper clad laminates, high-frequency flexible thin multilayer boards, high-frequency components, Wi-Fi (registered trademark) RF lines, and Wi-Fi (Registered Trademark) antennas, millimeter wave band antennas, digital lines, and base films used for parts for millimeter wave radars.

Claims (4)

a polyimide film;
A polyester layer made of a solvent-soluble liquid crystal polyester laminated on at least one surface of the polyimide film;
A laminate comprising: Liquid crystalline polyester soluble in the solvent,
The following monomers (A) to (C):
[Monomer (A)] bifunctional aromatic hydroxycarboxylic acid,
[Monomer (B)] bifunctional aromatic dicarboxylic acid,
[Monomer (C)] at least one compound selected from the group consisting of bifunctional aromatic diols and bifunctional aromatic hydroxylamines;
At least one of the monomer (B) and the monomer (C) contains a compound for forming a flexible structural unit, and the content of the compound for forming a flexible structural unit is the above 20 to 40 mol % of the linear liquid crystal polymer chains relative to the total molar amount of the monomers (A) to (C) are the following monomers (D):
[Monomer (D)] an aromatic compound having 3 to 8 functional groups of at least one selected from the group consisting of a hydroxy group, a carboxyl group and an amino group;
and the content of the monomer (D) is 0.01 to 10 mol per 100 mol of the total molar amount of the monomers (A) to (C). The laminate according to claim 1, characterized in that there is a the monomer (A) is at least one selected from the group consisting of 4-hydroxybenzoic acid, 4-(4-hydroxyphenyl)benzoic acid and 2-hydroxy-6-naphthoic acid;
The monomer (B) is at least one selected from the group consisting of 2,6-naphthalenedicarboxylic acid, isophthalic acid, terephthalic acid, 4,4'-biphenyldicarboxylic acid and diphenyl ether-4,4'-dicarboxylic acid. can be,
The monomer (C) is 3-aminophenol, 4-aminophenol, 1-amino-7-naphthol, 4,4′-biphenol, bisphenolfluorene, biscresolfluorene, 1,1′-bi-2-naphthol, At least one selected from the group consisting of methylhydroquinone, phenylhydroquinone, and 6-methyl-3-aminophenol, and
The compound for forming the flexible structural unit includes isophthalic acid, diphenyl ether-4,4′-dicarboxylic acid, 3-aminophenol, 6-methyl-3-aminophenol, 1-amino-7-naphthol, bisphenolfluorene, bis 3. The laminate according to claim 2, which is at least one selected from the group consisting of cresol fluorene and 1,1'-bi-2-naphthol. The monomer (D) is 3,5-dihydroxybenzoic acid, 1,3,5-trihydroxybenzene, 2,5-dihydroxyterephthalic acid, 1,5-dihydroxynaphthalene-2,6-dicarboxylic acid, 1,6 -dihydroxynaphthalene-2,5-dicarboxylic acid, 1,4-dihydroxy-2-naphthoic acid, 1,3,5-benzenetricarboxylic acid, 5-hydroxyisophthalic acid, and benzenetetracarboxylic acid 4. The laminate according to claim 2 or 3, wherein the laminate is at least one kind.