JP2024082217A - Tetracarboxylic dianhydrides, polyesterimides, and polyesterimide films - Google Patents

Abstract

The present invention provides a tetracarboxylic dianhydride that can be used to produce polyesterimide having low water absorption and low dielectric tangent. The tetracarboxylic dianhydride is represented by the following general formula (1): TIFF2024082217000030.tif27161, in which Ar1 in the general formula (1) contains a 2,6-naphthalene structure. [Selected Figure] None

Description

TECHNICAL FIELD The present invention relates to a tetracarboxylic dianhydride, a polyesterimide, a polyesterimide film, a flexible printed wiring board for high-speed communication, and a heat-resistant insulating substrate.

Lightweight electronic circuit boards that can be repeatedly bent and unfolded, and can be folded into complex shapes for implementation;
In addition, flexible printed circuit boards (FPCs) have recently come to be widely used in personal computers, mobile phones, digital cameras, printers, hard disks, medical equipment, automotive electrical components, and the like.

FPCs are usually made by forming a copper circuit on an electrical insulating film (base film material) made of polyimide having solder heat resistance. For example, in order to ensure strong adhesion between the circuit and the polyimide film, the polyimide film and copper foil are bonded together using a strong adhesive such as an epoxy resin/acrylic rubber system to prepare a copper-clad laminate, and then the copper foil is etched (subtractive method) using photolithography and an _FeCl3 aqueous solution to produce the FPC.

で表される分子構造を有するＫａｐｔｏｎ^（Ｒ）Ｈフィルムである。これはＦＰＣのベー
スフィルム材に求められる基本的特性、即ち、短期耐熱性（ガラス転移温度：Ｔ_ｇ）、電
気絶縁信頼性、膜純度、機械的特性、耐薬品性、銅箔密着性および難燃性を全て満足して
いる。 The polyimide film, which is currently in the highest demand as a base film material for FPCs, is obtained from pyromellitic dianhydride (PMDA) as a tetracarboxylic dianhydride component and 4,4'-oxydianiline (4,4'-ODA) as a diamine component, represented by the following formula (8):

The ^Kapton® H film has a molecular structure represented by the following formula: This film satisfies all of the basic properties required for a base film material of an FPC, namely, short-term heat resistance (glass transition temperature: _Tg ), electrical insulation reliability, film purity, mechanical properties, chemical resistance, copper foil adhesion, and flame retardancy.

In recent years, as FPCs become more highly precise, the tolerance for misalignment of circuits has become stricter, and emphasis has been placed on the dimensional stability of the base film material (thermal dimensional stability in the XY directions) against the thermal cycle during device manufacturing. In order to ensure thermal dimensional stability, it is desirable that the _Tg of the base film material is much higher than the solder reflow temperature (260°C), and that the coefficient of linear thermal expansion (CTE) in the XY directions is sufficiently low in the glass region below _Tg .

Most common polymer films have insufficient heat resistance, and their _Tg is much lower than the solder reflow temperature. In addition, their CTE (50-100 ppm/K) is much higher than the CTE (17-18 ppm/K) of the copper foil used as the circuit material, resulting in poor thermal dimensional stability.
Although the ^apton® H film has a lower CTE than general polymer films, it is still higher than the CTE of copper foil, and there is room for improvement in terms of thermal dimensional stability.

で表される分子構造を有するポリイミドフィルム、Ｕｐｉｌｅｘ^（Ｒ）Ｓ等が知られてい
る。 Polyimide films with improved thermal dimensional stability are also available on the market.
and ^Kapton® EN, which is made from 3,3′,4,4′-biphenyltetracarboxylic dianhydride (s-BPDA) and p-phenylenediamine (p-PDA) and has a lower CTE than copper foil, represented by the following formula (9):

Polyimide films having a molecular structure represented by ^{the following formula (1)} and Upilex® S are known.

Furthermore, with the recent shift to 5G, a new communications standard that enables high-speed, large-capacity, and low-latency communications for mobile communications devices such as smartphones, it has become an urgent task to significantly reduce the dielectric loss originating from electrically insulating substrates at higher operating frequencies (≧3.6 GHz) than conventional ones for FPC components that connect the antenna unit and main circuit board of mobile communications devices.

In order to suppress the dielectric loss occurring in the insulating layer of the FPC, it is effective to keep the dielectric loss tangent (tan δ) of the polyimide film itself, which is the base film material, low. However, with the current polyimide film, there is a problem that it is difficult in principle to dramatically reduce the dielectric loss tangent in the microwave range. For example, it has been reported that a polyimide film produced in a laboratory from PMDA and 4,4'-ODA exhibits a high dielectric loss tangent (0.0140 at 10 GHz) (see, for example, Non-Patent Document 1). This is thought to be due to the polarized imide group (O=C-N-C=O) that exists at a high content in the molecular structure of the polyimide. Therefore, as long as a polyimide film containing a large amount of imide groups is selected as the base film material, it is difficult to reduce the dielectric loss tangent, and for the same reason, the polyimide film showing the above-mentioned low CTE is not suitable for high-speed communication FPC applications.

However, since the imide group is the source of strong intermolecular forces based on dipole-dipole interactions and is an essential group supporting the heat resistance (extremely high T _g ) of polyimides, there is a risk that the excellent physical heat resistance (short-term heat resistance), which is the greatest feature of polyimides, will be significantly impaired if the imide group is simply eliminated.

In addition, high water absorption can be a serious problem in conventional polyimide films. This is believed to be due to the presence of polarized imide groups contained in a high content in the polyimide structure, as is the cause of the increase in the dielectric tangent mentioned above. If the water absorption is high, there is a risk that the film will undergo dimensional changes that exceed the allowable range due to moisture absorption. In addition, the dielectric loss of water is very large, so that water adsorbed or absorbed into the film will accelerate the increase in the dielectric tangent of the polyimide film.

As described above, it is theoretically difficult to achieve high thermal dimensional stability (low CTE), low water absorption, and low dielectric tangent at a higher level while maintaining the excellent properties inherent to conventional polyimide films, as long as polyimide resin is selected as the base film material for FPCs. Therefore, a method has been proposed that uses modified polyimide, specifically polyesterimide, instead of polyimide to solve the above problem (see, for example, Non-Patent Document 2). Polyesterimide is a polymer having an ester group (ester bond) and an imide group (imide bond) in the polymer skeleton.

で表されるテトラカルボン酸二無水物（ＴＡ－ＨＱ）を用い、これと剛直な構造を有する
汎用ジアミン（例えばｐ－ＰＤＡ）を組み合わせることで、低熱膨張性を確保しながら、
従来のテトラカルボン酸二無水物（ＰＭＤＡ、ｓ－ＢＰＤＡ等）を用いた場合に比べて吸
水率の低い耐熱性フィルムが得られる。 According to this technique, a monomer having an aromatic ring linked at a para or similar bonding position via an ester group, such as a monomer represented by the following formula (10):

By combining this with a general-purpose diamine having a rigid structure (e.g., p-PDA), it is possible to obtain a low thermal expansion while maintaining the following:
A heat-resistant film having a lower water absorption rate can be obtained as compared to the case where a conventional tetracarboxylic dianhydride (PMDA, s-BPDA, etc.) is used.

In order to further reduce the water absorption rate while maintaining excellent physical heat resistance (high Tg) and excellent thermal dimensional stability (low CTE), it is effective to use tetracarboxylic acid dianhydrides represented by the following formulas (11) to (13), in which aromatic rings are increased and extended further in the longitudinal direction of the molecule than in TA-HQ via ester linking groups.

For example, by using a tetracarboxylic dianhydride represented by the above formula (13) in which the aromatic rings have been increased to six rings, and by co-polymerizing this with a diamine having a rigid structure (p-PDA) and a diamine having a bent structure (4,4'-ODA) in an appropriate ratio, a uniform and viscous precursor varnish of polyesterimide can be obtained without precipitation or gelation. This is applied to a substrate, dried, and then heated at a high temperature to cause a dehydration ring-closing reaction (thermal imidization), thereby obtaining a polyesterimide film having an extremely high _Tg , an ultralow CTE, a low water absorption rate, sufficient flexibility, and an extremely low dielectric tangent at 10 GHz.

The effect obtained by increasing the number of rings and extending the tetracarboxylic dianhydride structure in the longitudinal direction of the molecule (both the water absorption coefficient and the dielectric loss tangent are gradually decreased) is considered to be due to the relative decrease in the content of imide groups, which have large molar polarization, in the polyesterimide structure. Therefore, by using not only the tetracarboxylic dianhydride represented by the above formula (13) but also a tetracarboxylic dianhydride that has been further increased in number and extended, the water absorption coefficient and the dielectric loss tangent can be further reduced.
However, further ring-increasing measures result in a decrease in the content of carboxy groups in the polyimide precursor structure, which governs the solubility of the polyimide precursor in a solvent (solubility in a solvent may be referred to as "solvent solubility" in this specification). This results in a decrease in the content of carboxy groups in the polyimide precursor structure, which governs the solubility of the polyimide precursor in a solvent (solubility in a solvent may be referred to as "solvent solubility"
If the solvation of the resulting polyimide precursor becomes insufficient, precipitation or gelation may occur, which may make it difficult to carry out the subsequent film formation step.

Further ring-enhancing of the tetracarboxylic dianhydride also has the problem that it becomes difficult to carry out due to the more obvious obstacles described below.
For example, the tetracarboxylic dianhydride represented by the above formula (13) is generally reacted with trimellitic anhydride chloride ((a), trimellitic acid (TMAC) in reaction formula (14)) at room temperature or lower in an aprotic solvent in the presence of an acid acceptor according to the following reaction formula (14), to form a bisphenol (reaction formula (14):
In the above, (b)) can be reacted to obtain the above-mentioned compound.

In this case, the bisphenol (b) is designed to have a rigid and linear structure in order to impart low thermal expansion to the polyesterimide film, and therefore does not have very high solubility in solvents.
As expected, when the bisphenol (b) is further ring-multiplied and extended, the resulting bisphenol no longer has solubility in a solvent, and it is difficult to synthesize the bisphenol in advance. This is a major obstacle that prevents further ring-multiplication.

ACS Applied Polymer Materials,3, 362 (2021). Polymers for Advanced Technologies, 31, 389 (2020).

An object of the present invention is to provide a tetracarboxylic dianhydride that can be used for producing a polyesterimide having low water absorption and low dielectric tangent. Another object of the present invention is to provide a polyesterimide having low water absorption and low dielectric tangent. Still another object of the present invention is to provide
The present invention provides a flexible printed wiring board and a heat-resistant insulating board for high-speed communication, which are highly reliable and have reduced dielectric loss.

Based on the above findings and considerations, the present inventors have further intensively studied and found that, when the aromatic rings are multiplied and extended in the longitudinal direction of the molecule, a naphthalene structure having bonding positions at the 2- and 6-positions (2,6-naphthalene structure) can be introduced to ensure sufficient solvent solubility while maintaining the rigidity and linearity of the bisphenol structure, and that this structure can be used to synthesize a symmetric ester group-containing tetracarboxylic acid dianhydride with a large number of rings that has not been seen before in a simple and efficient manner. Furthermore, the present inventors have found that this structure can be used to obtain a polyesterimide film that is suitable as an insulating material for high-speed communication FPCs, which is extremely useful in terms of its characteristics, and have completed the present invention. In this specification, polyesterimide is a polymer having an ester group (ester bond) and an imide group (imide bond) in the polymer skeleton.

で表され、
前記一般式（１）中、Ａｒ_１が、下記式（２）～（６）：

のいずれかで表される、
テトラカルボン酸二無水物。
［２］ 下記一般式（７）：

で表される構造単位を含み、
前記一般式（７）中、Ａｒ_１は前記式（２）～（６）のいずれかで表され、Ａｒ_２は２
価の芳香族基、２価の脂肪族基、または芳香族基と脂肪族基の少なくとも一方を含む２価
の基である、
ポリエステルイミド。
［３］ 上記［２］に記載のポリエステルイミドを含む、フィルム（本明細書において、
「ポリエステルイミドフィルム」という場合がある。）。
［４］ 熱機械分析によって測定された１００～２００℃の間の平均線熱膨張係数が、３
０ｐｐｍ／Ｋ以下である、上記［３］に記載のフィルム。
［５］ 動的粘弾性分析により測定されたガラス転移温度が、３００℃以上であるかまた
は検出されない、上記［３］に記載のフィルム。
［６］ 吸水率が、０．５％以下である、上記［３］に記載のフィルム。
［７］ 動作周波数１０ＧＨｚにおける誘電正接が、０．００３以下である、上記［３］に記載のフィルム。
［８］ 上記［３］～［７］のいずれか１項に記載のフィルムを含む、高速通信用フレキ
シブルプリント配線基板。
［９］ 上記［３］～［７］のいずれか１項に記載のフィルムを含む、耐熱絶縁基板。 The present invention includes the following embodiments, but is not limited to the following embodiments.
[1] The following general formula (1):

It is expressed as
In the general formula (1), Ar ₁ is represented by the following formulas (2) to (6):

It is represented by either
Tetracarboxylic dianhydride.
[2] The following general formula (7):

The structural unit represented by
In the general formula (7), Ar ₁ is represented by any one of the formulas (2) to (6), and Ar ₂ is
a divalent aromatic group, a divalent aliphatic group, or a divalent group containing at least one of an aromatic group and an aliphatic group,
Polyesterimide.
[3] A film comprising the polyesterimide according to [2] above (in the present specification,
It is sometimes called "polyesterimide film."
[4] The average linear thermal expansion coefficient between 100 and 200 ° C. measured by thermomechanical analysis is 3
The film according to the above [3], wherein the film has a viscosity of 0 ppm/K or less.
[5] The film according to the above [3], which has a glass transition temperature of 300° C. or higher or not detectable as measured by dynamic viscoelastic analysis.
[6] The film according to the above [3], having a water absorption rate of 0.5% or less.
[7] The film according to the above [3], having a dielectric loss tangent of 0.003 or less at an operating frequency of 10 GHz.
[8] A flexible printed circuit board for high-speed communication, comprising the film according to any one of [3] to [7] above.
[9] A heat-resistant insulating substrate comprising the film according to any one of the above [3] to [7].

According to an embodiment of the present invention, a tetracarboxylic dianhydride that can be used for producing a polyesterimide having low water absorption and low dielectric loss tangent can be provided. According to another embodiment of the present invention, a polyesterimide having low water absorption and low dielectric loss tangent can be provided.
According to still another embodiment of the present invention, it is possible to provide a flexible printed wiring board and a heat-resistant insulating substrate for high-speed communication, which are highly reliable and have reduced dielectric loss.

FIG. 1 is an infrared absorption spectrum of a thin film of the polyesterimide precursor described in Example 5. FIG. 2 is an infrared absorption spectrum of the polyesterimide thin film described in Example 5. FIG. 3 is an infrared absorption spectrum of the polyesterimide precursor thin film described in Example 8. FIG. 4 is an infrared absorption spectrum of the polyesterimide thin film described in Example 8.

In the numerical ranges described in stages in this specification, the upper limit or lower limit described in a certain numerical range may be replaced with the upper limit or lower limit of another numerical range. In addition, the upper limit or lower limit of the numerical range described in this specification may be replaced with a value shown in an example. A certain numerical value may be selected from the upper limit numerical value and the lower limit numerical value described in stages in this specification to form a stepped numerical range. In addition, the upper limit numerical value and the lower limit numerical value described in this specification may be replaced with a value shown in an example.
In the present specification, each component may contain multiple types of the corresponding substance. When multiple types of substances corresponding to each component are present in the composition, the content or amount of each component means the total content or amount of the multiple substances present in the composition, unless otherwise specified.
In this specification, the term "process" includes not only a process that is independent of other processes, but also a process that cannot be clearly distinguished from other processes, as long as the initial effect of the process is achieved.
In this specification, the term "film" includes a continuous film and a discontinuous film. The thickness of the "film" may be uniform or non-uniform. The outer edge in the plane direction and the outer edge in the thickness direction of the "film" are
Each of these can be either clear or unclear. The same goes for "layers."

The present invention provides a novel tetracarboxylic dianhydride having a ring length increased and extended in the longitudinal direction of the molecule through a series of ester linking groups, and a polyesterimide film obtained by using the same. First, the novel tetracarboxylic dianhydride and a method for producing the same are described below. However, the method for producing the novel tetracarboxylic dianhydride is not limited to the following.

<Tetracarboxylic acid dianhydride and its production method>
The tetracarboxylic dianhydride according to one embodiment of the present invention is represented by the above general formula (1). In the general formula (1), Ar ₁ is any one of the above formulas (2) to (6).

The tetracarboxylic acid dianhydride represented by the general formula (1) is a symmetric ester group-containing tetracarboxylic acid dianhydride having an unprecedented large ring extension containing a 2,6-naphthalene structure, and has sufficient solubility in a solvent while maintaining rigidity and linearity.

Ar ₁ may be any one of formulas (3) to (6), preferably any one of formulas (4) to (6), more preferably formula (4) or (6), and even more preferably formula (6).

A method for producing the tetracarboxylic dianhydride represented by the general formula (1) will be described below, but the method is not limited thereto. In the following production method, sufficient solubility in a solvent can be ensured by introducing a 2,6-naphthalene structure during ring growth and elongation in the longitudinal direction of the molecule, so that the tetracarboxylic dianhydride represented by the general formula (1) can be synthesized simply and efficiently.

Among the tetracarboxylic dianhydrides represented by the general formula (1), one example is a tetracarboxylic dianhydride represented by the following formula (15):
A method for producing the tetracarboxylic dianhydride represented by the formula (I) is described below.

The tetracarboxylic dianhydride represented by the above formula (15) is synthesized via a route represented by the following reaction formula (16).

First, in the presence of a strong acid catalyst, the hydroxy group of the starting material, 6-hydroxy-2-naphthalenecarboxylic acid ((d) in the above reaction formula (16)) is acetylated and protected with acetic anhydride (Ac ₂ O) to give 6-acetoxy-2-naphthalenecarboxylic acid ((c) in the above reaction formula (16)).
(e)) is obtained.
Specifically, the starting material (d), an excess amount of acetic anhydride, and a catalytic amount of acid (eg, concentrated sulfuric acid) are placed in a reaction vessel, and refluxed in a nitrogen atmosphere at 80 to 140° C. for 1 to 5 hours to obtain a homogeneous solution.
This is cooled to room temperature to precipitate the product. The precipitate is collected by filtration, washed, and
Drying in vacuum at .about.150.degree. C. for 1-24 hours gives the acetylated product (e).

Next, a process for obtaining an ester group-containing diacetoxy compound (h) by esterification of an acetylated compound (e) with 2,6-dihydroxynaphthalene (g) will be described. In the esterification reaction, the carboxyl group of the acetylated compound (e) is converted to obtain an acid chloride (f), which is then reacted with 2,6-dihydroxynaphthalene (g) (acid halide method), or a method of esterification using a condensing agent can be used. The acid halide method will be described below.

The chlorinating agent used in the chlorination reaction of the acetylated compound (e) is not particularly limited, and examples thereof include thionyl chloride, sulfuryl chloride, oxalyl chloride, N-chlorosuccinimide,
Examples of the chlorinating agent include phosgene, methanesulfonyl chloride, methoxyacetyl chloride, phosphorus trichloride, phosphorus pentachloride, phosphorus oxychloride, N-chlorophthalimide, trichloroisocyanuric acid, trichloromethanesulfonyl chloride, and 1,3-dichloro-5,5-dimethylhydantoin. The reactivity may be increased by adding a catalytic amount of N,N-dimethylformamide (DMF) or pyridine to the chlorinating agent to generate a Vilsmeier reagent in the reaction system. Thionyl chloride is preferably used from the viewpoints of safety, economy, ease of removal of the chlorinating agent when an excessive amount is added, and ease of removal of by-products.

When the chlorinating agent used is liquid, such as thionyl chloride, it is possible to use the chlorinating agent as both the chlorinating agent and the solvent without using a solvent. When the liquid chlorinating agent is easy to remove by distillation, the chlorinating agent may be added in a large excess amount relative to the substrate. When removing the excess chlorinating agent by distillation, an azeotropic agent may be used. For example, when removing the excess thionyl chloride after the reaction is completed, the efficiency of the removal by distillation can be improved by using toluene or benzene as an azeotropic agent.

In the above chlorination, a solvent may be used as necessary. The solvent that can be used is not particularly limited as long as it does not react with the chlorinating agent and dissolves the acetylated product (e). Examples of the solvent include dichloromethane, chloroform, toluene, benzene, N,N-dimethylformamide, and tetrahydrofuran. It is preferable that these solvents are dehydrated.
These may be used in combination of two or more kinds. When a solvent is used, the amount of the chlorinating agent added is, for example, 1.1 to 10, preferably 2 to 5, per mole of the acetylated compound (e).
The reaction temperature during chlorination varies depending on the boiling point of the chlorinating agent and the boiling point of the solvent used, but is, for example, 20 to 150° C., preferably 50 to 100° C. The reaction time is, for example, 30 minutes to 6 hours, preferably 1 to 4 hours.

After the chlorination reaction is completed, the excess chlorinating agent, solvent, and by-products are removed to obtain the target acid chloride (f) almost quantitatively. For example, when chlorination is performed with thionyl chloride using DMF as a catalyst, the by-product is a gas (sulfur dioxide), so that after the reaction is completed, high-purity acid chloride (f) can be obtained simply by adding benzene or toluene to the reaction solution and azeotropically removing the excess liquid. However, the acid chloride (f) may be purified by recrystallization from a suitable solvent. In this case, the solvent that can be used is not particularly limited as long as it does not react with the acid chloride (f) and allows the recrystallization operation to be performed. For example, n-hexane, cyclohexane, benzene,
non-polar hydrocarbon solvents such as toluene; ester solvents such as methyl acetate, ethyl acetate, propyl acetate, and γ-butyrolactone; ketone solvents such as acetone, methyl ethyl ketone, diethyl ketone, cyclopentanone, and cyclohexanone; ether solvents such as tetrahydrofuran, 1,4-dioxane, and diethyl ether; N,N-dimethylformamide, N,N
Examples of suitable solvents include amide solvents such as N-dimethylacetamide, N-methylpyrrolidone, and 1,3-dimethyl-2-imidazolidinone, and sulfone solvents such as dimethylsulfoxide and sulfolane. Two or more of these may be mixed and used. It is preferable that these solvents are sufficiently dehydrated. From the viewpoint of the water content in the solvent and the recrystallization efficiency, cyclohexane,
Hydrocarbon solvents such as benzene and toluene are preferably used.

In the reaction of acid chloride (f) with 2,6-dihydroxynaphthalene (g), a predetermined amount of 2,6-dihydroxynaphthalene (g) and an acid acceptor are dissolved in a dehydrated solvent in a well-dried reaction vessel, and the vessel is sealed with a septum cap to obtain liquid A. Next, a predetermined amount of acid chloride (f) is dissolved in a dehydrated solvent, and the vessel is sealed with a septum cap to obtain liquid B. Liquid B is set to a predetermined temperature and stirred, while liquid A is gradually added to liquid B with a syringe. During this process,
The total solute concentration after addition of Solution A is, for example, 5 to 50% by mass, preferably 7 to 30% by mass. The reaction is carried out, for example, at −20 to 70° C., preferably 0 to 50° C., for example, for 1 to 72 hours, preferably 2 to 48 hours.

The solvents of the A solution and the B solution used in the above reaction may be the same or different. The solvent that can be used is not particularly limited as long as it does not react with the added acid chloride (f), 2,6-dihydroxynaphthalene (g) and acid acceptor and dissolves them well. For example, ester solvents such as methyl acetate, ethyl acetate, propyl acetate, and γ-butyrolactone (GBL) and the like, amide solvents such as N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, and 1,3-dimethyl-2-imidazolidinone, sulfone solvents such as dimethylsulfoxide and sulfolane, ether solvents such as tetrahydrofuran and 1,4-dioxane, and ketone solvents such as acetone, methyl ethyl ketone, diethyl ketone, cyclopentanone, and cyclohexanone, and the like can be mentioned. Two or more of these may be mixed and used. It is preferable that these solvents are sufficiently dehydrated. GBL is preferably used from the viewpoint of dissolving power.

In the above esterification reaction, in order to avoid the production of undesired monoesters,
The amount of f) used is preferably set to be slightly more than the equivalent amount (2 times the molar amount) of the diol. When the diol is taken as 1 mole, the molar ratio is, for example, 2.01 to 5, preferably 2.01 to 5.
From the standpoint of economy and separation efficiency, it is preferable that the acid chloride (f) is not used in excess, and that the molar ratio is 5 or less.

In the above esterification reaction, an organic tertiary amine can be used as an acid acceptor to be added, and although there is no particular limitation, examples that can be used include pyridine, picoline, quinoline, N,N-dimethylaniline, N,N-diethylaniline, triethylamine, tripropylamine, and tributylamine. Pyridine is preferably used from the viewpoints of toxicity, economy, and ease of separation of the acid acceptor added in excess and the by-product hydrochloride. The amount of the acid acceptor to be added is, for example, 1 to 10 times the molar amount, preferably 2 to 5 times the theoretical amount (mol) of hydrogen chloride to be generated.
It is double the molar amount.

After the esterification reaction, the precipitate is first washed with a non-polar solvent such as toluene to remove excess acid chloride (f), then washed with a small amount of the reaction solvent, and then washed with water to remove the by-product hydrochloride, and is repeatedly washed with water using a 1% aqueous silver nitrate solution until no white precipitate of silver chloride is observed in the wash.

The esterification reaction can be carried out by the acid halide method described above, or by a method using a dehydration condensation agent.
Usable condensation agents are not particularly limited, but examples thereof include dicyclohexylcarbodiimide (D
Examples of the carbodiimide-based condensing agent include carbodiimide-based condensing agents such as diisopropylcarbodiimide (DIC) and 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC). These may be used in combination with 4-dimethylaminopyridine or 1-hydroxybenzotriazole. In addition to the carbodiimide-based condensing agents, imidazole-based condensing agents such as N,N'-carbonyldiimidazole, 4-(4,6-dimethoxy-1,3,5-triazine-2-
In terms of reaction efficiency, economic efficiency, and ease of removing by-products, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide, N,N'-diisopropylcarbodiimide, and the like are preferably used as the condensation agent.

Next, the terminal acetoxy group of the ester group-containing diacetoxy compound (h) obtained as described above is hydrolyzed with an alkali to deprotect the compound, thereby obtaining an ester group-containing bisphenol (i).
The above reaction is specifically carried out as follows: The ester group-containing diacetoxy compound (h) is dissolved in a solvent, a base is added thereto, and the mixture is stirred, for example, at 0 to 50° C. for 5 minutes to 3 hours to complete the hydrolysis of the terminal acetoxy group. The completion of the reaction is confirmed by thin layer chromatography (T
The reaction can then be monitored by LC. After that, the reaction is neutralized by adding acid to obtain bisphenol (i
) was precipitated, filtered, washed, and vacuum dried to obtain bisphenol (i) in an almost quantitative yield.
is obtained.

During the hydrolysis, the diacetoxy body (h) may be dissolved in a solvent, and an aqueous alkali solution may be added to the solution. The solvent that can be used in this case is not particularly limited as long as it is stable to bases, is miscible with an aqueous alkali solution, and dissolves the diacetoxy body (h). Examples of the solvent include amide solvents such as N,N-dimethylformamide, N,N-dimethylacetamide, and N-methyl-2-pyrrolidone, sulfone solvents such as dimethylsulfoxide and sulfolane, cyclic ester solvents such as γ-butyrolactone, ether solvents such as tetrahydrofuran and 1,4-dioxane, alcohol solvents such as methanol and ethanol, and glycol solvents such as ethylene glycol. Two or more of these may be mixed and used.

During the hydrolysis, sodium hydrogen sulfate may be added to suppress oxidation of the terminal hydroxyl groups of bisphenol (i) produced by the hydrolysis. The amount of sodium hydrogen sulfate added is not particularly limited, but is, for example, about 0.1 to 1% by mass based on the total volume.

In the hydrolysis reaction, concentrated aqueous ammonia (28% by mass) is preferably used as the base, but dilute solutions of strong inorganic bases such as sodium hydroxide and potassium hydroxide can also be used. The concentration of the aqueous solution of strong inorganic base is not particularly limited, and is, for example, 0.1 to 2N. The hydrolysis reaction is carried out, for example, at -20 to 50°C, preferably 0 to 30°C, for example, for 5 minutes to 12 hours, preferably 10 minutes to 20 minutes.
When using a strong inorganic base as the base, it is possible to obtain the ethoxylated form (
Not only the terminal acetoxy group of h) but also the ester group can be prevented from being hydrolyzed.

The acid used in the neutralization reaction after the hydrolysis reaction is not particularly limited, and an aqueous solution of an inorganic acid such as hydrochloric acid or an organic acid such as acetic acid can be used. The concentration of the acid used is not particularly limited, and is, for example, 0.1 to 2N. After the hydrolysis, in order to precipitate bisphenol (i), an acid is added so that the reaction solution becomes weakly acidic. The pH of the solution is not particularly limited, and is, for example, pH 2 to 5, preferably pH 5.
Adjust to 3-4.

The esterification step for obtaining the tetracarboxylic dianhydride represented by the general formula (1) using the bisphenol (i) obtained as described above will be described below. In addition to the acid halide method using trimellitic anhydride chloride (TMAC), a method of directly esterifying the carboxy group of trimellitic anhydride (TMA) and the hydroxy group of bisphenol (i) using a condensing agent can be applied to this reaction. Since TMAC is available at low cost,
From the viewpoints of economy and reaction efficiency, the acid halide method is preferably used, and will be described below.

In a well-dried reaction vessel, a predetermined amount of bisphenol (i) and an acid acceptor are dissolved in a dehydrated solvent, and the vessel is sealed with a septum cap to obtain liquid A. Next, a predetermined amount of TMAC is dissolved in a dehydrated solvent, and the vessel is sealed with a septum cap to obtain liquid B. Liquid B is set to a predetermined temperature and stirred, while liquid A is gradually added to liquid B with a syringe. At that time, the total solute concentration after the addition of liquid A is, for example, 5 to 50 mass%, preferably 7 to 30 mass%. The reaction is carried out, for example, at -20 to 70°C, preferably 0 to 50°C, for example, for 1 to 72 hours, preferably 2 to 48 hours. After the reaction is completed, the precipitate is filtered, washed, and dried to obtain the desired tetracarboxylic dianhydride (j).

The solvents for the A and B solutions used in the above reaction may be the same or different. The solvents that can be used are not particularly limited as long as they do not react with the added TMAC, bisphenol (i) and acid acceptor and dissolve them well. Examples of suitable solvents include N,N-dimethylformamide, N,N-dimethylacetamide (DMAc), N-methylpyrrolidone (N
Examples of suitable solvents include amide solvents such as dimethylsulfoxide and sulfolane, ester solvents such as methyl acetate, ethyl acetate, propyl acetate and γ-butyrolactone (GBL), ether solvents such as tetrahydrofuran and 1,4-dioxane, and ketone solvents such as acetone, methyl ethyl ketone, diethyl ketone, cyclopentanone and cyclohexanone. Two or more of these may be mixed and used. It is preferable that these solvents are sufficiently dehydrated. Solubility, economy,
From the viewpoints of safety and ease of processing, NMP and GBL are preferably used.

In the above esterification reaction, in order to avoid the formation of undesired monoesters, and in order to avoid the formation of TMA
Considering that C is inexpensively available and easy to remove, it is desirable to set the amount of TMAC used to be in excess of the equivalent amount (2 times the molar amount) to bisphenol (i). When bisphenol (i) is taken as 1 mole, the molar ratio is, for example, 2.05 to 5, and preferably 2.1 to 1.
The answer is 3.

In the above esterification reaction, an organic tertiary amine can be used as the acid acceptor to be added, and although there is no particular limitation, examples that can be used include pyridine, picoline, quinoline, N,N-dimethylaniline, N,N-diethylaniline, triethylamine, tripropylamine, and tributylamine. It is preferable that these are dehydrated in advance. From the viewpoints of toxicity, economy, and ease of separation of the excess acid acceptor added and the by-product hydrochloride, pyridine is preferably used. The amount of acid acceptor to be added is determined based on the theoretical amount (mol) of hydrogen chloride to be generated.
The molar amount is, for example, 1 to 10 times, and preferably 2 to 5 times, that of the above.

After the esterification reaction, the precipitate was first washed with a non-polar solvent such as toluene to remove excess T.
The MAC is removed, and then the by-product hydrochloride is removed by washing with water, using a 1% aqueous silver nitrate solution and repeatedly washing with water until no white precipitate of silver chloride is observed in the washings. When washing with water, some of the terminal acid anhydride groups are hydrolyzed and ring-opened. This can be dried in a vacuum at, for example, 150 to 250°C, preferably 170 to 220°C, for example, for 1 to 24 hours, preferably 2 to 12 hours, to completely close the ring of some of the ring-opened groups.

In addition to the acid halide method, the above esterification reaction can also be carried out using a method using a dehydration condensation agent. The condensation agent that can be used is not particularly limited, and examples thereof include carbodiimide-based condensation agents such as dicyclohexylcarbodiimide (DCC), diisopropylcarbodiimide (DIC), and 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC). These may be added in combination with 4-dimethylaminopyridine, 1-hydroxybenzotriazole, or the like. In addition to carbodiimide-based condensation agents, imidazole-based condensation agents such as N,N'-carbonyldiimidazole, 4-(4,6-dimethoxy-1,3,5-triazine-
A triazine-based condensing agent such as 1-(2-yl)-4-methylmorpholinium chloride n-hydrate can also be used. From the viewpoints of reaction efficiency, economy, and ease of removing by-products, 1-(2-yl)-4-methylmorpholinium chloride n-hydrate is preferably used as the condensing agent.
N,N'-ethyl-3-(3-dimethylaminopropyl)carbodiimide, N,N'-diisopropylcarbodiimide, and the like are preferably used.

The tetracarboxylic dianhydride (j) obtained as described above has a sufficiently high purity and can be directly used in the method for producing a polyesterimide precursor described later, but can also be further purified by recrystallization from a suitable solvent. In this case, the recrystallization solvent is not particularly limited as long as it does not react with the tetracarboxylic dianhydride (j) and can perform the recrystallization operation, and examples of the recrystallization solvent include cyclic ester solvents such as γ-butyrolactone (GBL), amide solvents such as N,N-dimethylformamide, N,N-dimethylacetamide, and N-methylpyrrolidone, and sulfone solvents such as dimethylsulfoxide. Two or more of these may be mixed and used. It is preferable that the solvent is sufficiently dehydrated. From the viewpoints of dissolving power, safety, and recrystallization efficiency, amide solvents such as NMP and GBL are preferably used.

<Method of producing polyesterimide precursor>
A polyesterimide containing a structural unit represented by general formula (7) can be obtained by dehydrating and ring-closing a polyesterimide precursor. Since the polyesterimide precursor contains a structure represented by any one of formulas (2) to (6) into which a 2,6-naphthalene structure has been introduced, it is possible to prepare the polyesterimide precursor while avoiding precipitation and gelation.

A method for producing a polyesterimide precursor will be described below, but the method is not limited thereto and any known method can be used.
First, a diamine is dissolved in a polymerization solvent, and then a powder of a tetracarboxylic dianhydride represented by the general formula (1) is added thereto. The mixture is sealed and stirred at, for example, 0 to 100° C., preferably 20 to 60° C., for example, for 1 to 100 hours, preferably 2 to 72 hours.

In the above polymerization reaction, the molar ratio of diamine to tetracarboxylic dianhydride charged in a reaction vessel is 0.8 to 1.1, preferably 0.9 to 1.1, and more preferably 0.95 to 1.05, per 1 part of diamine. When the diamine and tetracarboxylic dianhydride are charged in substantially equimolar amounts, the degree of polymerization of the polyesterimide precursor can be increased.

The raw material monomer (solid content) concentration at the start of polymerization is, for example, 5 to 50 mass %, preferably 10 to 40 mass %. When the viscosity of the polymerization solution increases due to an increase in the degree of polymerization of the polyesterimide precursor, causing an impediment to effective stirring, the polymerization solution may be appropriately diluted with the same dehydrated solvent. The raw material monomer contains at least a tetracarboxylic acid anhydride represented by the general formula (1) and a diamine.

The solvent used in the polymerization reaction is not particularly limited as long as it sufficiently dissolves the raw material monomers and the polyesterimide precursor produced and does not react with them. For example, N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone (NMP),
Amide solvents such as 1,3-dimethyl-2-imidazolidinone and hexamethylphosphortriamide, cyclic ester solvents such as γ-butyrolactone (GBL), sulfone solvents such as dimethylsulfoxide and sulfolane, ketone solvents such as cyclopentanone and cyclohexanone, m
Phenol-based solvents such as 1-cresol, p-cresol, 3-chlorophenol, 4-chlorophenol, etc. can be used. Two or more of these may be mixed and used. NMP is preferably used from the viewpoints of dissolving power, safety, and economy.

In the above polymerization reaction, it is desirable to select an aromatic diamine that can be used within a range that does not impair the polymerization reactivity, the uniformity of the reaction solution, and the required properties of the polyesterimide film. In this specification, the aromatic diamine contains at least an aromatic group in the molecule, and may contain an aromatic group and an aliphatic group. Usable aromatic diamines are not particularly limited, but examples thereof include p-phenylenediamine, m-phenylenediamine, 2,4-diaminotoluene,
2,5-diaminotoluene, 2,4-diaminoxylene, 2,4-diaminodurene, 4
, 4'-methylenedianiline, 4,4'-methylenebis(3-methylaniline), 4,4
'-methylenebis(3-ethylaniline), 4,4'-methylenebis(2-methylaniline), 4,4'-methylenebis(2-ethylaniline), 4,4'-methylenebis(3,
5-dimethylaniline), 4,4'-methylenebis(3,5-diethylaniline), 4,
4'-methylenebis(2,6-dimethylaniline), 4,4'-methylenebis(2,6-
diethylaniline), 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl ether, 2,4'-diaminodiphenyl ether, 2,2'-diaminodiphenyl ether, 4,4'-diamino-2,2'-
Bis(trifluoromethyl)diphenyl ether, 4,4'-diaminodiphenyl sulfone, 3,3'-diaminodiphenyl sulfone, 4,4'-diaminobenzophenone, 3,
3'-Diaminobenzophenone, 4,4'-diaminobenzanilide, benzidine, 3,
3'-Dihydroxybenzidine, 3,3'-dimethoxybenzidine, o-tolidine, m-
tolidine, 2,2'-bis(trifluoromethyl)benzidine, 1,4-bis(4-aminophenoxy)benzene, 1,4-bis(3-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, 1,3-bis(3-aminophenoxy)benzene, 4,4'-bis(4-aminophenoxy)biphenyl, bis(4-(3-aminophenoxy)phenyl)sulfone, bis(4-(4-aminophenoxy)phenyl)sulfone,
2,2-bis(4-(4-aminophenoxy)phenyl)propane, 2,2-bis(4-
Examples of such an aminophenyl ester include 4-aminophenyl hexafluoropropane, 2,2-bis(4-aminophenyl)hexafluoropropane, p-terphenylenediamine, 4-aminophenyl 4-aminobenzoate, 4-amino-2-methylphenyl 4-aminobenzoate, hydroquinone bis(4-aminobenzoate), methylhydroquinone bis(4-aminobenzoate), methoxyhydroquinone bis(4-aminobenzoate), phenylhydroquinone bis(4-aminobenzoate), bis(4-aminophenyl)terephthalate, and bis(4-amino-2-methylphenyl)terephthalate. Two or more of these may be used in combination (copolymerized).

In the polymerization reaction, it is desirable to select an aliphatic diamine that can be used within a range that does not impair the polymerization reactivity, the uniformity of the reaction solution, and the required properties of the polyesterimide film. In this specification, the aliphatic diamine contains at least an aliphatic group and does not contain an aromatic group in the molecule. The usable aliphatic diamine is not particularly limited, but for example, trans-
1,4-cyclohexanediamine (t-CHDA), cis-1,4-cyclohexanediamine, 4,4'-methylenebis(cyclohexylamine), 4,4'-methylenebis(3
-methylcyclohexylamine), 4,4'-methylenebis(3-ethylcyclohexylamine), 4,4'-methylenebis(3,5-dimethylcyclohexylamine), 4,4
'-Methylenebis(3,5-diethylcyclohexylamine), isophoronediamine, 1
, 4-cyclohexanebis(methylamine), 2,5-bis(aminomethyl)bicyclo[
2.2.1]heptane, 2,6-bis(aminomethyl)bicyclo[2.2.1]heptane, 3,8-bis(aminomethyl)tricyclo[5.2.1.0]decane, 1,3-diaminoadamantane, 2,2-bis(4-aminocyclohexyl)propane, 2,2-bis(
4-aminocyclohexyl)hexafluoropropane, 1,3-propanediamine, 1,
4-Tetramethylenediamine, 1,5-Pentamethylenediamine, 1,6-Hexamethylenediamine, 1,7-Heptamethylenediamine, 1,8-Octamethylenediamine, 1,
9-nonamethylenediamine, siloxane-containing diamine, etc. Two or more of these may be used in combination (copolymerization). Furthermore, these aliphatic diamines may be used in combination with the aromatic diamines described above.

In the above polymerization reaction, aromatic tetracarboxylic dianhydrides other than the tetracarboxylic dianhydride represented by the general formula (1) can be used as a copolymerization component in the range that does not impair the polymerization reactivity, the uniformity of the reaction solution, and the required properties of the polyesterimide film. The aromatic tetracarboxylic dianhydride that can be used in this case is not particularly limited, but examples thereof include pyromellitic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 1,2,3',4,4'-biphenyltetracarboxylic dianhydride, 1,2,3',4,4'-biphenyltetracarboxylic dianhydride, 1,3,4',5 ...
,4-phenylenebis(trimellitate anhydride), 2-methyl-1,4-phenylenebis(trimellitate anhydride), 2-methoxy-1,4-phenylenebis(trimellitate anhydride), 3,3',4,4'-benzophenonetetracarboxylic dianhydride, 3,3',4,4'-biphenylethertetracarboxylic dianhydride, 3,3',4,4'-biphenylsulfonetetracarboxylic dianhydride, 2,2'
-bis(3,4-dicarboxyphenyl)hexafluoropropanoic dianhydride, 2,2'
Examples of the copolymerizable components include 1,4,5,8-naphthalenetetracarboxylic dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, and the like. Two or more of these may be used. The amount of these copolymerizable components used is, for example, 0.1 to 50 mol %, preferably 1.0 to 50 mol %, based on the total amount of tetracarboxylic dianhydride.
The range is 40 mol %.

In the above polymerization reaction, aliphatic tetracarboxylic dianhydrides can be used in combination as copolymerization components in addition to the tetracarboxylic dianhydride represented by the general formula (1) within the scope of not impairing the polymerization reactivity, the uniformity of the reaction solution, and the required properties of the polyesterimide film. The aliphatic tetracarboxylic dianhydrides that can be used in this case are not particularly limited, but examples thereof include bicyclo[2.2.2]oct-7-ene-2,3,5,6-tetracarboxylic dianhydride, bicyclo[2.2.2]octane-2,3,5,6-tetracarboxylic dianhydride, bicyclo[2.2.2]heptane tetracarboxylic dianhydride, tetrahydrofuran-2,4-dicarboxylic dianhydride, and the like.
, 3,4,5-tetracarboxylic dianhydride, 3c-carboxymethylcyclopentane-1
r,2c,4c-tricarboxylic acid 1,4:2,3-dianhydride, bicyclo-3,3',4,
Examples of the dianhydride include 4'-tetracarboxylic acid dianhydride, 1,2,4,5-cyclohexanetetracarboxylic acid dianhydride (1,2,3,4-cyclobutanetetracarboxylic acid dianhydride, 1,3-dimethyl-1,2,3,4-cyclobutanetetracarboxylic acid dianhydride, and 1,2,3,4-cyclopentanetetracarboxylic acid dianhydride. Two or more of these may be used. The amount of the aliphatic tetracarboxylic acid dianhydride (copolymerization component) used is, for example, in the range of 0.1 to 40 mol %, and preferably 1 to 30 mol %, of the total tetracarboxylic acid dianhydrides. The aliphatic tetracarboxylic acid dianhydride (copolymerization component) and the aromatic tetracarboxylic acid dianhydride (copolymerization component) may be used in combination.

From the viewpoint of handling of the polyesterimide precursor varnish and the physical properties of the polyesterimide film, the intrinsic viscosity of the polyesterimide precursor is preferably in the range of 0.5 to 5.0 dL/g, and more preferably in the range of 1.0 to 3.0 dL/g. The intrinsic viscosity of the polyesterimide precursor is a value obtained by measuring a solution of the polyesterimide precursor adjusted to a solids concentration of 0.5 mass % at 30° C. with an Ostwald viscometer.

The polyesterimide precursor varnish obtained by the above-mentioned production method may be appropriately diluted with a solvent, for example, for the purpose of adjusting the solution viscosity to an appropriate level for the cast film-forming process. The above-mentioned polymerization solvents can be used for dilution. Usually, the varnish is diluted with the same solvent as that used for polymerization, but it may be diluted with a different solvent as long as the uniformity of the varnish is not impaired. In addition, two or more types of solvents may be mixed and used as the dilution solvent. It is preferable that these dilution solvents are dehydrated in advance.

The polyesterimide precursor varnish obtained by the above-mentioned manufacturing method can be used as it is, or after being appropriately diluted with the above-mentioned dilution solvent, it can be dropped into a large amount of poor solvent such as water or methanol to precipitate as a fibrous powder, and then filtered, washed, and dried to isolate the polyesterimide precursor. The isolated powder can be dissolved again in a solvent to obtain a uniform varnish. In this case, the above-mentioned polymerization solvent can be used for redissolution. Usually, it is dissolved in the same solvent as that used in polymerization, but it may be dissolved in a different solvent as long as the uniformity of the varnish is not impaired. In addition, two or more types of solvents may be mixed and used as the solvent for redissolution (sometimes referred to as "redissolution solvent" in this specification). It is desirable that these redissolution solvents have been dehydrated in advance. In order to promote redissolution, the solution is heated, for example, at 30 to 120°C, preferably 40 to 80°C, for example, for 1 minute to 4 hours, preferably for 5 minutes to 120°C.
May be heated for 1 hour.

In order to stabilize the viscosity of the polyesterimide precursor varnish obtained by polymerization or to appropriately lower the molecular weight of the polyesterimide precursor, the polyesterimide precursor varnish obtained by polymerization is diluted or redissolved, and then diluted with water to a concentration of, for example, 50 to 100 ml.
It may be heated at 30° C., preferably 70 to 120° C., for example, for 10 minutes to 6 hours, preferably 30 minutes to 4 hours.

For the purpose of partially imidizing the polyesterimide precursor, the polyesterimide precursor varnish obtained by polymerization is heated, either directly or after dilution or after redissolution, at, for example, 70 to 160° C., preferably 80 to 100° C., while taking care not to cause precipitation or gelation.
The mixture may be heated at 150° C. for, for example, 10 minutes to 6 hours, preferably 30 minutes to 4 hours.

For the purpose of partially imidizing the polyesterimide precursor, a chemical imidization agent containing an organic tertiary amine and a dehydrating ring-closing agent is added to the polyesterimide precursor varnish obtained by polymerization, either directly or after dilution or after redissolution, while taking care not to cause precipitation or gelation, and the mixture is heated at, for example, 0 to 100° C., preferably 20 to 60° C., for example, at 1 to 48° C.
The mixture may be stirred for a period of time, preferably for 2 to 24 hours.

The organic tertiary amine in the chemical imidization agent is not particularly limited, but for example, pyridine, picoline, N,N-dimethylaniline, N,N-diethylaniline, triethylamine, tripropylamine, tributylamine, etc. can be used. From the viewpoints of toxicity and economy, pyridine is preferably used. Furthermore, the dehydration ring-closing agent in the chemical imidization agent is not particularly limited, but for example, acid anhydrides such as acetic anhydride, propionic anhydride, butyric anhydride, isobutyric anhydride, etc. can be used. From the viewpoints of ease of removal and economy, acetic anhydride is preferably used.

The mixing ratio (mass ratio) of the dehydrating ring-closing agent and the organic tertiary amine in the chemical imidization agent is not particularly limited. When the mass of the dehydrating ring-closing agent is 1 g, the mass of the organic tertiary amine is, for example, in the range of 0.1 to 2 g, and preferably in the range of 0.2 to 1 g.

The amount of the chemical imidizing agent added when partially imidizing the polyesterimide precursor is
The amount of the dehydrating ring-closing agent contained therein is added in a molar amount in the range of 0.05 to 0.2 times the amount of carboxy groups in the polyesterimide precursor, i.e., the theoretical amount of dehydration (molar amount).
This can prevent precipitation from occurring in the reaction solution and prevent gelation from occurring.

Various additives, such as a polymer other than polyesterimide, an inorganic filler, an adhesion promoter, a release agent, a flame retardant, an ultraviolet stabilizer, a surfactant, a leveling agent, an antifoaming agent, a fluorescent brightening agent, a crosslinking agent, a polymerization initiator, and a photosensitizer, may be added to the varnish of the polyesterimide precursor obtained as described above, so long as the additives do not impair the required properties of the polyesterimide film.

<Polyesterimide and its manufacturing method>
A polyesterimide according to one embodiment of the present invention contains a structural unit represented by the above general formula (7). In the general formula (7), Ar ₁ is represented by any one of the above formulas (2) to (6), and Ar ₂ is
is a divalent aromatic group, a divalent aliphatic group, or a divalent group containing at least one of an aromatic group and an aliphatic group. The divalent group containing at least one of an aromatic group and an aliphatic group may be a group containing an aromatic group, a group containing an aliphatic group, or a group containing an aromatic group and an aliphatic group. The divalent group containing at least one of an aromatic group and an aliphatic group may further contain any group. The "divalent group containing at least one of an aromatic group and an aliphatic group" may be a group other than a "divalent aromatic group" and a "divalent aliphatic group".

A polyesterimide containing a structural unit represented by general formula (7) has a low water absorption rate because the concentration of imide groups is reduced by introducing an ester group, and also has a low dielectric tangent because it contains a structural unit in which aromatic rings are increased along the polymer chain by a 2,6-naphthalene structure.

Ar ₁ may be any of formulas (3) to (6), preferably any of formulas (4) to (6), more preferably formula (4) or (6), and even more preferably formula (6). Ar ₁ may be a structure derived from a tetracarboxylic dianhydride represented by general formula (1).

From the viewpoint of obtaining a polyesterimide film having low water absorption, low dielectric tangent, low thermal expansion, and high elasticity, Ar ₂ is preferably a divalent aromatic group, and more preferably a phenylene group. From the viewpoint of obtaining a polyesterimide film having a particularly low dielectric tangent, _{Ar 2} is preferably a divalent group containing an aromatic group and an oxy group (ether bond), and more preferably a diphenyl ether group (-Ph-O-Ph- group (Ph is a phenylene group)). From the viewpoint of obtaining a polyesterimide film having a particularly low water absorption and dielectric tangent, Ar ₂ is preferably a divalent group containing an aromatic group and an oxycarbonyl group (ester bond). From the viewpoint of reducing the dielectric constant, Ar ₂ is preferably a divalent group containing an aromatic group, an oxy group (ether bond), and an isopropylidene group, and more preferably a bis(phenoxyphenyl)propane group (-Ph-O-Ph-C ₃ H ₆ -Ph-O-Ph- group (Ph is a phenylene group)). The aromatic group and the aliphatic group in the divalent aromatic group, the divalent aliphatic group, or the divalent group containing at least one of an aromatic group and an aliphatic group may each be substituted or unsubstituted. The divalent aromatic group, the divalent aliphatic group, or the divalent group containing at least one of an aromatic group and an aliphatic group, which is _Ar2 , may each have a structure derived from the above-mentioned aromatic diamine or aliphatic diamine.

The polyesterimide may further include a structural unit including a structure derived from an aromatic tetracarboxylic dianhydride other than the tetracarboxylic dianhydride represented by general formula (1), a structural unit including a structure derived from an aliphatic tetracarboxylic dianhydride, or both of these structural units.

The polyesterimide represented by the general formula (7) can be produced by dehydrating and ring-closing the polyesterimide precursor. The method for dehydrating and ring-closing the polyesterimide precursor is not particularly limited.
Known methods such as thermal imidization and chemical imidization can be applied. The thermal imidization is preferred because it is simple, and the heating temperature is, for example, 230 to 400° C., preferably 250 to 370° C.
It is.

<Polyesterimide film>
The polyesterimide film according to one embodiment of the present invention contains at least polyesterimide, and may contain various additives such as polymers other than polyesterimide, inorganic fillers, adhesion promoters, release agents, flame retardants, UV stabilizers, surfactants, leveling agents, defoamers, fluorescent brighteners, crosslinking agents, polymerization initiators, and photosensitizers depending on the application.

The following is an example of a method for producing a polyesterimide film, but the method is not limited thereto. A cast film-forming method can be preferably used for producing a polyesterimide film. A uniform varnish of the polyesterimide precursor obtained as described above is applied onto a support (substrate) made of various materials, such as glass, copper, aluminum, stainless steel, silicon, etc., and
In a hot air dryer, for example, at 40 to 150° C., preferably 50 to 130° C., for example, for 10 minutes to 4
The film is dried for a period of time, preferably 30 minutes to 2 hours, to obtain a film of the polyesterimide precursor.

A polyesterimide film can be produced by heating the polyesterimide precursor film obtained as described above on a substrate in vacuum or in an inert gas such as nitrogen at, for example, 230 to 400° C., preferably 250 to 370° C. The temperature may be raised stepwise. Thermal imidization is preferably carried out in vacuum or in an inert gas, but may be carried out in air as long as the imidization temperature is not too high.

The imidization of the polyesterimide precursor film is usually carried out by heating at a high temperature as described above, but it can also be carried out by immersing the polyesterimide precursor film in a bath of the above-mentioned chemical imidization agent. The immersed film may be washed and dried, and then further heat-treated.

After the thermal imidization step, the laminate of the polyesterimide film and the substrate may be immersed in a water or alcohol bath, etc., and the polyesterimide film may be peeled off from the substrate to form a free-standing film, which may then be further heat-treated in vacuum, in an inert gas, or in air for the purpose of removing residual strain, etc. In this case, the temperature conditions of the heat treatment may be appropriately selected in order to suppress adverse effects such as deformation of the polyesterimide film and an increase in CTE due to relaxation of orientation.

The polyesterimide film has an average linear thermal expansion coefficient between 100 and 200°C measured by thermomechanical analysis of, for example, 60 ppm/K or less, preferably 30 ppm/K or less, more preferably 10 ppm/K or less. The lower limit is not particularly limited. The average linear thermal expansion coefficient is a value in the film surface (XY) direction of a polyesterimide film (25 μm thick) obtained as an average value in the range of 100 to 200°C from the elongation of a test piece (e.g., length: 20 mm, width: 5 mm, chuck length: 15 mm) at a temperature increase rate of 5°C/min, with a static load of 0.5 g per 1 μm of film thickness applied to the test piece using a thermomechanical analyzer.

The polyesterimide film has a glass transition temperature measured by dynamic viscoelastic analysis of:
For example, it is preferable that the temperature is 300° C. or higher or not detected, and more preferably 340° C. or higher.
The glass transition temperature is preferably 350° C. or higher, and more preferably 350° C. or higher. The glass transition temperature can be determined from the peak temperature of a loss modulus curve measured using a dynamic viscoelasticity measuring device in a nitrogen atmosphere, at a frequency of 0.1 Hz, at a heating rate of 5° C./min, and in a temperature range of room temperature to 450° C.

The polyesterimide film has a water absorption rate of, for example, 1.0% or less, preferably 0.5% or less.
The water absorption is preferably 0.3% or less, more preferably 0.3% or less. The lower limit is not particularly limited.
According to the method of Example 1, K 7209, the mass (W ₀ ) of a polyesterimide film that has been vacuum dried at 50° C. for 24 hours is weighed, and the film is then immersed in water at 23° C. for 24 hours, after which excess water is wiped off and the mass (W) is weighed, and the mass can be calculated from the formula: W _A =(W−W ₀ )/W ₀ ×100(%).

The polyesterimide film has a dielectric loss tangent of, for example, 0.05% at an operating frequency of 10 GHz.
The dielectric loss tangent is 0.004 or less, preferably 0.003 or less, and more preferably 0.002 or less. There is no particular lower limit.
After placing it in an environment of 100 MPa (relative humidity) for 24 hours, it can be measured by the cavity resonator perturbation method under the same temperature and humidity conditions.

Polyesterimide film is used for high-speed transmission FPC substrates, heat-resistant insulating substrates, high-speed transmission FP
The film can be suitably used as a heat-resistant insulating substrate (base film) for C, etc. The operating frequency of high-speed transmission FPC is, for example, 3.6 GHz or more. These substrates are extremely beneficial in terms of characteristics, since the polyesterimide film has low water absorption and low dielectric tangent, and can simultaneously improve reliability and reduce dielectric loss. The thickness of the film is not particularly limited and can be adjusted as appropriate. When used as a heat-resistant insulating substrate for FPC, the film thickness is 10 to 6
The preferred range is 0 μm.

The present invention will be described in detail below with reference to examples, but is not limited to these examples. The physical properties in the examples were measured by the following methods.

<Infrared absorption (FT-IR) spectrum>
The infrared absorption spectra of the synthesized monomer (tetracarboxylic anhydride) and its intermediates were measured using a Fourier transform infrared spectrophotometer (FT-IR4100 manufactured by JASCO Corporation) with KBr.
The infrared absorption spectra of the polyesterimide precursor and a thin film (about 5 μm thick) of polyesterimide were measured by a transmission method.

< ^1H -NMR spectrum>
^{The 1} H-NMR spectra of the synthesized monomers and their intermediates were measured using a JEOL NMR spectrometer.
Using a spectrophotometer (ECP400), deuterated dimethyl sulfoxide (DMSO-d ₆ )
Alternatively, the measurements were performed using deuterated chloroform (CDCl ₃ ) as a solvent.

<Elemental analysis>
Organic trace elemental analyzer (MICRO CORDER J manufactured by J Science Labs)
M10) was used to analyze the C, H, and N chemical composition of the synthesized monomer and its intermediates.

<Differential scanning calorimetry (melting point)>
The melting points of the synthesized monomers and their intermediates were measured using a differential scanning calorimeter (DSC3100, manufactured by Netsch Japan) or a thermogravimetric analyzer (TG-DTA20, manufactured by Netsch Japan).
00S) in a nitrogen atmosphere at a heating rate of 5° C./min. The peak temperature of the thermogram was determined.

<Intrinsic Viscosity (η _inh )>
The reduced viscosity (η _red ) of the polyesterimide precursor was measured at 30° C. using an Ostwald viscometer after diluting a varnish obtained by polymerization of a polyamic acid, which is a polyesterimide precursor, with a polymerization solvent to prepare a solution with a solid content concentration of 0.5% by mass. This value can be regarded as substantially the intrinsic viscosity (η _inh ), and the higher this value, the higher the molecular weight of the polyamic acid. Usually, if the reduced viscosity measured under these conditions is 1.0 dL/g or more, it can be regarded as a sufficiently high molecular weight.

<Glass transition temperature ( _Tg )>
The glass transition temperature (T g ) of the polyesterimide film (25 μm thick) was calculated from the peak temperature of the loss modulus curve measured in a nitrogen atmosphere at a frequency of 0.1 Hz, a heating rate of 5° C./min, and a temperature range of room temperature to 450° C. using a dynamic viscoelasticity measuring device ( _Q800 ) manufactured by TA Instruments.
A higher _Tg indicates better physical heat resistance (short-term heat resistance).

<Coefficient of Linear Thermal Expansion (CTE)>
Using a thermomechanical analyzer (TMA4000) manufactured by Netzsch Japan or a thermomechanical analyzer (TMA8311) manufactured by Rigaku Corporation, a static load of 0.5 g per 1 μm of film thickness was applied to a test piece (length: 20 mm, width: 5 mm, chuck length: 15 mm), and the CTE in the film plane (XY) direction of the polyesterimide film (25 μm thick) was determined as the average value in the range of 100 to 200° C. from the elongation of the test piece at a heating rate of 5° C./min. The lower this value, the more excellent the thermal dimensional stability in the glassy temperature range.

<5% weight loss temperature (T _d ⁵ )>
Using a thermogravimetric analyzer (TG-DTA2000S) manufactured by Netsch Japan, the temperature at which the weight of a polyesterimide film (25 μm thick) lost 5% of its initial weight during heating in nitrogen and air flow at a heating rate of 10° C./min was measured. The higher the T _d ⁵ value measured in nitrogen, the higher the chemical heat resistance (thermal stability) and the more the generation of volatile organic compounds (VOCs) is suppressed up to higher temperatures.

<Mechanical properties: tensile modulus (E), breaking elongation (ε _b ), breaking strength (σ _b )>
The mechanical properties of the polyesterimide film (test piece: 30 mm long × 3 mm wide × 25 μm thick) were measured at a stretching speed of 8 mm/min using a tensile tester (Tensilon UTM-2) manufactured by A&D Co., Ltd. The tensile modulus (E) was calculated from the initial gradient of the stress-strain curve, and the breaking elongation (ε _b ) and breaking strength (σ _b ) were calculated from the elongation and stress at the time the film broke.

<Water absorption rate ( _WA )>
According to JIS K 7209, the mass (W ₀ ) of a polyesterimide film (film thickness 20 to 30 μm) that had been vacuum dried at 50° C. for 24 hours was weighed, and the film was then immersed in water at 23° C. for 24 hours, after which excess water was wiped off and the mass (W) was weighed. W _A =(W −W ₀ ).
The water absorption rate ( _WA ) was calculated from the following equation:/ _W0 ×100(%).

<High-frequency dielectric properties: dielectric constant (ε _r ), dielectric tangent (tan δ)>
The high frequency dielectric properties (10 GHz) of polyesterimide film are as follows:
After placing it in an environment of 50% RH (relative humidity) for 24 hours, it was measured under the same temperature and humidity conditions by a cavity resonator perturbation method (compliant with IEC62810, PNA network analyzer N5222B manufactured by Keysight Technologies, and cavity resonator for 10 GHz CP531 manufactured by Kanto Electronics Application Development Co., Ltd.).

<Synthesis of tetracarboxylic dianhydride>
[Example 1: Synthesis of 8-ring tetracarboxylic dianhydride (TDCA) monomer]
The tetracarboxylic dianhydride of Example 1 was synthesized according to the following reaction formula (16') and the procedure shown below.

[Acetylation]
First, 6-hydroxy-2-naphthalenecarboxylic acid ((d) in reaction formula (16')) was acetylated as follows.
In a 300 mL three-neck flask, 6-hydroxy-2-naphthalenecarboxylic acid (17.11 g
The mixture was stirred with a magnetic stirrer under nitrogen atmosphere at 100°C for 3 hours to obtain a brown transparent solution. The solution was cooled to room temperature to separate a precipitate, which was then filtered and washed with water and then with toluene, and then vacuum dried at 120°C for 12 hours to obtain a cream-colored product (yield 78%).

The analytical results of this product are as follows: FT-IR (KBr plate method, cm ⁻¹ ): 3
053 (aromatic C-H stretch), 2987/2845 (aliphatic C-H stretch), 2684 (hydrogen bonded carboxyl group, O-H stretch), 1761 (acetoxy group, C=O stretch), 168
0 (hydrogen-bonded carboxy group, C=O stretch), 1223 (acetoxy group, C-O stretch).
^1H -NMR (400MHz, DMSO- _d6 , δ, ppm): 13.11 (s, 1H(
Relative integrated intensity: 0.90H), COOH), 8.64 (s, 1H (1.15H), 1-proton of 6-acetoxy-2-naphthalene carboxylic acid unit (6A2NA), 8.1
8 (d, 1H (1.07H), J = 8.9 Hz, 8-proton of 6A2NA), 8.03
-7.99 (m, 2H (2.27H), 3-proton + 4-proton of 6A2NA), 7
.77 (sd, 1H (1.15H), J = 2.2 Hz, 5-proton of 6A2NA), 7
.42 (dd, 1H (1.09H), J=8.9, 2.2Hz, 7-proton of 6A2NA), 2.34 (s, 3H (3.00H), CH ₃ ). Melting point (TG-DTA): 203°C
From these analytical results, it was found that the product was the desired acetylated product (in reaction formula (16'), (e
)) was confirmed.

[Chlorination]
Next, the acetylated product (e) obtained as above was chlorinated as follows.
In a 300 mL eggplant-shaped flask, 15.37 g (49 mmol) of the acetylated product (e), thionyl chloride (30 mL, 300 mmol), and N,N-dimethylformamide (
The mixture was refluxed at 80°C for 3 hours in a nitrogen atmosphere to obtain a yellow transparent solution. After the reaction, benzene was added as an azeotropic agent to remove thionyl chloride by azeotropic distillation to precipitate a yellow powder. This was recrystallized from cyclohexane, and the crystals were filtered and dried in vacuum at 60°C for 12 hours to obtain yellow crystals (yield 78%).

The analytical results of this product are as follows: FT-IR (KBr plate method, cm ⁻¹ ): 3
⁰⁶³ (aromatic C-H stretch), 1741 (acetoxy group + acid chloride, C=O stretch).
H-NMR (400 MHz, CDCl ₃ , δ, ppm): 8.74 (s, 1H (1.04
H), 6-acetoxy-2-naphthalenecarboxylic acid chloride unit (6A2NC)
-proton), 8.08-8.02 (m, 2H (2.18H), 8-proton + 3-proton of 6A2NC), 7.88 (d, 1H (1.09H), J = 8.7 Hz, 6A2NC
4-proton of 6A2NC), 7.65 (sd, 1H (1.04H), 5-proton of 6A2NC,
J = 2.0 Hz), 7.37 (dd, 1H (1.06H), J = 8.9, 2.2 Hz, 6
A2NC 7-proton), 2.38 (s, 3H (3.00H), CH ₃ ). Melting point (TG
-DTA): 127° C. From these analytical results, it was confirmed that the product was the desired acid chloride ((f) in reaction formula (16′)).

[Bisesterification]
Next, an esterification reaction was carried out using the acid chloride (f) obtained as described above and 2,6-dihydroxynaphthalene (g).
In a 100 mL eggplant-shaped flask, 4.80 g (2
9.9 mmol) was dissolved in 20 mL of dehydrated γ-butyrolactone (GBL), and 8 mL (100 mmol) of pyridine was added as an acid acceptor, and the mixture was sealed with a septum cap to obtain solution A. Next, in a 500 mL eggplant-shaped flask, 16.93 g of acid chloride (f) was added.
(68 mmol) was dissolved in 210 mL of GBL and sealed with a septum cap to obtain liquid B. While stirring liquid B at room temperature, liquid A was gradually added to liquid B using a syringe, and stirring was continued for 12 hours. The precipitate was filtered off, washed with toluene and then with GBL to remove excess acid chloride, and finally washed thoroughly with water to completely remove the by-product pyridine hydrochloride. This was vacuum dried at 160°C for 12 hours to obtain a cream-colored product (yield 82%).

In the above reaction, if the solvent solubility of the monoesterified intermediate (monoacetoxy body) in which only one of the two terminal hydroxy groups of 2,6-dihydroxynaphthalene has reacted with the acid chloride is extremely low, the precipitation of the unintended monoesterified intermediate (monoacetoxy body) occurs in parallel with the production of the desired bisesterified body, and a pure bisesterified body (diacetoxy body) cannot be obtained. However, in reality, when examined by TLC, the precipitated product did not contain the monoesterified intermediate. This suggests that both the monoesterified intermediate and the bisesterified body had sufficient solvent solubility. This is thought to be due to the unexpectedly large solubility-promoting effect of the introduction of the 2,6-naphthalene structure.

The analytical results of the product obtained are shown below: FT-IR (KBr plate method, cm ^-1 )
: 3068 (aromatic C-H stretch), 1757 (acetoxy group + acid chloride, C=O stretch)
, 1736 (aromatic ester group, C=O stretch). ¹ H-NMR (400 MHz, DMSO
-d ₆ , δ, ppm): 8.97 (sd, 2H (2.00H), J = 0.84 Hz, 1 of terminal 6-acetoxy-2-naphthalenecarboxylate unit (terminal 6A2NCE),
1'-proton), 8.32 (d, 2H (1.97H), J = 9.2 Hz, terminal 6A2N
CE 8,8'-protons), 8.22 (dd, 2H (1.91H), J = 8.6, 1.
7 Hz, 3,3'-protons of terminal 6A2NCE), 8.15-8.10 (m, 4H(4
.04H), 4,4'-protons of terminal 6A2NCE + 4,8-protons of central 2,6-naphthalene unit (central 26NA), 8.02 (sd, 2H (1.97H), J = 2
.4 Hz, 5,5'-protons of terminal 6A2NCE), 7.86 (sd, 2H (2.01
H), J = 2.4 Hz, 1,5-proton at the center of 26 NA), 7.62 (dd, 2H (1
95H), J = 8.9, 2.4 Hz, 7,7'-protons of terminal 6A2NCE), 7.
50 (dd, 2H (1.97H), J=8.8, 2.3 Hz, 3,7-protons at the center of 26 NA), 2.37 (s, 6H (5.94H), CH ₃ ). Melting point (TG-DTA): 22
0° C. From these analytical results, it was confirmed that the product was the desired pure ester group-containing diacetoxy compound ((h) in reaction formula (16′)).

[Hydrolysis of terminal diacetoxy groups]
Next, the terminal diacetoxy group of the ester group-containing diacetoxy compound (h) obtained as above was hydrolyzed to obtain bisphenol, as follows.

In a 500 mL eggplant-shaped flask, 4.55 g (8.4
The mixture was heated to 150°C and completely dissolved. The mixture was then cooled to 0°C and concentrated aqueous ammonia (
40 mL of 1N hydrochloric acid (28% by mass) was slowly added and the mixture was stirred at 0° C. for 20 minutes. After the reaction was completed, 60 mL of 1N hydrochloric acid was added to the solution to make it weakly acidic, causing a precipitate to form. The precipitate was separated by filtration and thoroughly washed with water. The mixture was vacuum-dried at 160° C. for 12 hours to obtain a cream-colored product (yield 94%).

The analytical results of this product are as follows: FT-IR (KBr plate method, cm ⁻¹ ): 3
419 (terminal hydroxyl group, O-H stretch), 3069 (aromatic C-H stretch), 1717 (
Ester group, C=O stretch). ^1H -NMR (400MHz, DMSO- _d6 , δ, ppm
): 10.33 (s, 2H (2.00H), OH), 8.79 (sd, 2H (1.95H)
), J = 1.4 Hz, terminal 6-hydroxy-2-naphthalenecarboxylate unit (
1,1'-protons of terminal 6H2NCE), 8.10-8.05 (m, 6H (5.94
H), 8,8'-protons + 3,3'-protons + 4,4'-protons of the terminal 6H2NCE), 7.97 (sd, 2H (1.87H), J = 2.4 Hz, 5,
5'-proton), 7.88 (d, 2H (1.99H), J = 8.8 Hz, central 26 NA
4,8-protons), 7.58 (dd, 2H (1.98H), J = 8.5, 2.5 Hz
, 7,7'-protons of terminal 6H2NCE), 7.27-7.22 (m, 4H (4.06
H), 1,5-proton + 3,7-proton of central 26NA). Melting point (TG-DTA):
From these analytical results, it was determined that the product was the desired ester group-containing bisphenol (
It was confirmed that the reaction was (i) in reaction formula (16').

[Esterification reaction of ester group-containing bisphenol with TMAC]
Next, the ester group-containing bisphenol (i) obtained as above was subjected to an esterification reaction with trimellitic anhydride chloride (TMAC) to obtain a tetracarboxylic dianhydride, as described below.

In a 100 mL eggplant-shaped flask, 3.58 g (7.
16 mmol) was dissolved in 20 mL of dehydrated NMP, and 5 mL (63 mmol) of pyridine was added as an acid acceptor. The mixture was sealed with a septum cap to obtain solution A.
In a 100 mL eggplant flask, 6.34 g (30 mmol) of TMAC was dissolved in 20 mL of NMP and sealed with a septum cap to obtain liquid B. While stirring liquid B at room temperature, liquid A was gradually added to liquid B using a syringe, and stirring was continued for 12 hours. The precipitate was filtered off, washed with toluene and then with GBL to remove excess acid chloride, and finally washed thoroughly with water to completely remove the by-product pyridine hydrochloride. This was vacuum dried at 200°C for 12 hours to obtain a light brown product (yield 68%).

When the ester group-containing bisphenol used in the above reaction has a significantly low solvent solubility, the bisesterification reaction must be carried out at a low concentration, which significantly reduces the reaction efficiency, product yield, and purity. However, in reality, the ester group-containing bisphenol used had a sufficiently high solvent solubility, so the above reaction could be carried out at a sufficiently high concentration. In addition, only one of the two terminal hydroxyl groups of the ester group-containing bisphenol was T.
When the solvent solubility of the monoesterified intermediate reacted with MAC is extremely low, precipitation of the monoesterified intermediate occurs simultaneously with the production of the desired bisesterified product, making it impossible to obtain a pure target product. However, in reality, the product did not contain the monoesterified intermediate. This suggests that the monoesterified intermediate retained sufficiently high solvent solubility. This is thought to be due to the unexpectedly large solubility enhancing effect of the introduction of the 2,6-naphthalene structure.

The analytical results of the product obtained are shown below: FT-IR (KBr plate method, cm ^-1 )
: 3065 (aromatic C-H stretch), 1858/1784 (anhydride group, C=O stretch), 1
737 (ester group, C=O stretch). ¹ H-NMR (400 MHz, DMSO-d ₆ , δ
, ppm): 9.04 (sd, 2H (2.00H), J = 1.8 Hz, 6H2NCE
, 1'-proton), 8.73-8.70 (m, 4H (4.17H), 3,3'-proton + 6,6'-proton of terminal phthalic anhydride unit (PAn), 8.42 (d, 2H
(1.83H), J = 8.6 Hz, 8,8'-protons of 6H2NCE), 8.33 (d
d, 2H (1.65H), J = 7.7, 0.8 Hz, 5,5'-protons of PAn), 8
． 27 (dd, 2H (2.37H), J = 8.4, 1.7 Hz, 6H2NCE 3,3'
-proton), 8.21 (d, 2H (2.18H), J = 8.6 Hz, 6H2NCE 4
, 4'-proton), 8.14-8.12 (m, 4H (3.88H), 6H2NCE 5
, 5'-proton + 1,5-proton of central 26NA), 8.04 (d, 2H (2.14
H), J = 8.6 Hz, 4,8-protons at the center of 26 NA), 7.77 (dd, 2H (1
. 74H), J = 8.7, 2.1 Hz, 7,7'-protons of 6H2NCE), 7.65
(dd, 2H (2.38H), J=8.6, 2.1 Hz, 3,7-protons at center 26 NA). Elemental analysis (C ₅₀ H ₂₄ O ₁₄ , molecular weight 848.73): Estimated C; 70.76%
, H; 2.85%, Analysis value C; 70.61%, H; 3.06%. Melting point (TG-DTA):
284° C. From these analytical results, it was confirmed that the product was the target tetracarboxylic dianhydride represented by the following formula (15) ((j) in reaction formula (16′)).

[Example 2: Synthesis of 7-ring TCDA monomer]
Except for using hydroquinone instead of 2,6-dihydroxynaphthalene (g),
The tetracarboxylic dianhydride of Example 2 was synthesized according to the above reaction formula (16'). In Example 2, too, no undesirable precipitation of monoesterified intermediates was observed in the step of synthesizing the ester group-containing bisphenol or in the step of reacting the bisphenol with TMAC to synthesize the tetracarboxylic dianhydride. This is thought to be due to the unexpectedly large solubility enhancing effect of the introduction of the 2,6-naphthalene structure, as in the case of Example 1.

The analytical results of the product obtained are shown below: FT-IR (KBr plate method, cm ^-1 )
: 3072 (aromatic C-H stretch), 1853/1779 (anhydride group, C=O stretch), 1
742 (ester group, C=O stretch). ¹ H-NMR (400 MHz, DMSO-d ₆ , δ
, ppm): 8.99 (s, 2H (2.13H), 1,1'-protons of 6H2NCE)
, 8.73-8.69 (m, 4H (3.86H), 3,3'-protons of PAn + 6,6
'-protons), 8.41 (d, 2H (2.07H), J = 9.0 Hz, 8,8'-protons of 6H2NCE), 8.33 (dd, 2H (2.22H), J = 7.8, 0.7 Hz
, 5,5'-protons of PAn), 8.25-8.2 (m, 4H (4.19H), 6H2
3,3'-protons + 4,4'-protons of NCE), 8.14 (sd, 2H (2.12
H), J = 1.9 Hz, 5,5'-protons of 6H2NCE), 7.76 (dd, 2H(
2.11H), J = 8.7, 2.3 Hz, 7,7'-protons of 6H2NCE), 7.5
2 (s, 4H (4.00H), 2,3,5,6-protons of the central hydroquinone unit). Elemental analysis (C ₄₆ H ₂₂ O ₁₄ , molecular weight 798.67): Estimated value C; 69.18%,
H: 2.78%, Analysis C: 68.78%, H: 3.13%. Melting point (DSC): 306°C
From these analytical results, it was confirmed that the product was the desired tetracarboxylic dianhydride represented by the following formula (17).

[Comparative Example 1: Synthesis of 8-ring TCDA monomer not having a 2,6-naphthalene structure]
A diacetoxy compound containing an ester group and a six-ring aromatic ring is synthesized by a bis-esterification reaction of 4,4'-biphenol and 4-(4-acetoxyphenyl)benzoic acid chloride.
The terminal diacetoxy group is then hydrolyzed to convert it into bisphenol, which is then mixed with TM
We attempted to synthesize a tetracarboxylic dianhydride having eight rings from AC. However,
In the first bis-esterification reaction, the precipitated product was mainly composed of an undesired one-side monoesterified intermediate (monoacetoxy compound), and it was difficult to obtain the desired bis-acetoxy compound containing a six-ring ester group, because the one-side monoesterified intermediate (monoacetoxy compound) has extremely low solubility in solvents.

<Polymerization of polyesterimide precursor, thermal imidization, and evaluation of polyesterimide film properties>
[Example 3: Preparation and evaluation of 8-ring TCDA/p-PDA-based polyesterimide film]
A polyesterimide precursor was polymerized from the tetracarboxylic dianhydride represented by the above formula (15) described in Example 1 and p-phenylenediamine (p-PDA) in the following manner.

In a well-dried sealed reaction vessel, p-PDA (2 mmol) was filtered through molecular sieves 4A.
The tetracarboxylic dianhydride powder (2 mmol) described in Example 1 was added to this solution while stirring with a magnetic stirrer, and stirring was continued (initial total solids concentration: 30% by mass). As the polymerization proceeded, the viscosity of the solution increased and it became impossible to stir sufficiently, so NMP was added appropriately, and finally, the solution was stirred at room temperature for 141 hours to obtain a uniform and viscous polyesterimide precursor varnish (final total solids concentration: 15.9% by mass).
The reduced viscosity of the polyesterimide precursor measured at 30° C. and a concentration of 0.5% by mass using an Ostwald viscometer was 1.24 dL/g, and a polyesterimide precursor with a sufficiently high molecular weight was obtained.

This polyesterimide precursor varnish was applied to a glass substrate and dried in a hot air dryer at 80° C. for 3 hours.
The film was then dried for 1 hour to obtain a cast film of polyesterimide precursor. The film was placed together with the glass substrate in an electric furnace and heated in a vacuum at 250°C for 1 hour and then at 350°C for 1 hour to perform thermal imidization. To remove residual stress, the film was peeled off from the glass substrate and further heat-treated in a vacuum at 350°C for 1 hour to obtain a clear, flexible polyesterimide film with a thickness of 25 μm. The physical properties of the obtained film were measured according to the above-mentioned methods.

Separately, infrared absorption spectra were measured for the thin film sample before and after thermal imidization. The thermal imidization treatment completely eliminated the amide group C=O stretching vibration absorption bands at around 1680 and 1530 cm ^-1 derived from the polyesterimide precursor, confirming that the thermal imidization reaction was completed under these heating conditions.

The polyesterimide film of Example 3 (film thickness 25 μm) had a very high glass transition temperature (371° C.) and an extremely low linear thermal expansion coefficient (3.8 pm/K). As a result of evaluating the mechanical properties, the tensile modulus (Young's modulus) was 7.70 GPa, indicating an ultra-high modulus of elasticity. The observed ultra-low thermal expansion and high elasticity are believed to be due to the rigidity and linearity of the polyesterimide main chain due to the use of monomers with rigid structures, both the tetracarboxylic dianhydride and the diamine, and the high degree of in-plane orientation of the main chain induced by thermal imidization. The 5% weight loss temperature was 467° C. in nitrogen, and the film also retained sufficiently high chemical heat resistance (long-term heat resistance). In addition, the polyesterimide film of Example 3 showed a very low water absorption rate (0.26%). This is believed to be due to the use of a novel tetracarboxylic dianhydride in which the ring is increased and extended in the longitudinal direction by introducing a 2,6-naphthalene structure, dramatically reducing the content of imide groups with high molar polarization contained in the polyesterimide structure. Furthermore, the 10 GH
The dielectric constant at z was 3.20, and the dielectric loss tangent was 0.00246. This dielectric loss tangent was a low value comparable to that of liquid crystal polyester. The physical properties are summarized in Table 1. Thus, the polyesterimide film of Example 3 had properties suitable for use as a heat-resistant insulating film material for high-speed communication FPC. In Table 1, items that were not evaluated are left blank.

[Example 4: Preparation and evaluation of 8-ring TCDA/4,4'-ODA based polyesterimide film]
As a diamine, 4,4'-oxydianiline (4,4'-ODA) was used instead of p-PDA.
A polyesterimide film was prepared by polymerization of the polyesterimide precursor, cast film formation, and thermal imidization in the same manner as in Example 3, except that a polyesterimide precursor was used, and the film properties were evaluated. The polyesterimide film had a very low water absorption (0.27%) like the polyesterimide film described in Example 3. The dielectric loss tangent was an extremely low value (0.00170), which was even lower than that of the polyesterimide film described in Example 3.

[Example 5: Preparation and evaluation of 7-ring TCDA/p-PDA-based polyesterimide film]
A polyesterimide precursor was polymerized and cast into a film in the same manner as in Example 3, except that the tetracarboxylic dianhydride represented by the formula (17) in Example 2 was used instead of the tetracarboxylic dianhydride represented by the formula (15) in Example 1.
A polyesterimide film was prepared by thermal imidization, and the film properties were evaluated. The film had excellent properties similar to those of the polyesterimide film described in Example 3. FIG. 1 shows the infrared absorption spectrum of the thin film sample (film of polyesterimide precursor) before thermal imidization.
FIG. 2 shows the infrared absorption spectrum of the thin film sample (polyesterimide film) after thermal imidization.

[Example 6: Preparation and evaluation of 7-ring TCDA/4,4′-ODA-based polyesterimide film]
A polyesterimide film was prepared by polymerization of a polyesterimide precursor, cast film formation, and thermal imidization in the same manner as in Example 3, except that the tetracarboxylic dianhydride represented by the above formula (17) described in Example 2 was used as the tetracarboxylic dianhydride and 4,4'-ODA was used as the diamine, and the film properties were evaluated. As with the polyesterimide film described in Example 4, the film had excellent properties in terms of low water absorption and low dielectric loss tangent.

Comparative Example 2: Preparation and Evaluation of TA-HQ/p-PDA-Based Polyesterimide Film
A polyesterimide film was prepared by polymerizing a polyesterimide precursor, casting the precursor, and thermally imidizing the precursor in the same manner as in Example 3, except that a tetracarboxylic dianhydride containing ester groups having a total of three rings, 1,4-phenylenebis(trimellitate anhydride) (TA-HQ), was used as the tetracarboxylic dianhydride, and p-PDA was used as the diamine. Some of the film properties were measured. The water absorption rate of the film in Comparative Example 2 was Kap
Although the value was lower than that of the ton ^(R) H film (2.5%), it was still high. This is because the ring multiplication of the TA-HQ used was insufficient, resulting in a small number of aromatic rings, and because it did not contain a 2,6-naphthalene structure, the imide group content in the obtained polyesterimide structure was still high.

[Example 2a: Synthesis of 6-ring TCDA monomer]
The tetracarboxylic dianhydride of Example 2a was synthesized according to the above reaction formula (16'), except that 4-acetoxybenzoic acid was used instead of the acetylated compound (e) (6-acetoxy-2-naphthalenecarboxylic acid). In Example 2a, as in Examples 1 and 2, no undesirable precipitation of monoesterified intermediates was observed.

The analytical results of the product obtained are as follows: FT-IR (KBr plate method, cm ⁻¹ ): 3111/3068 (aromatic C—H stretching), 1860/1781 (anhydride group, C═O stretching), 1747/1736 (ester group, C═O stretching), 1509 (1,4-phenylene). ¹ H-NMR (400 MHz, DMSO-d ₆ , δ, ppm): 8.70-8.68 (m, 4H (4.04H), 3,3'-protons + 6,6'-protons of PAn), 8.35 (d, 4H (3.92H), J = 8.9 Hz, 2,2',6,6'-protons of oxybenzoate (OBA) units), 8.31 (dd, 2H (2.11H), J = 7.6, 1.0 Hz, 5,5'-protons of PAn), 8.10 (d, 2H (2.13H), J = 8.8 Hz, 4,8-proton of central naphthalene (NA), 7.98 (sd, 2H (2.00H), J = 2.4 Hz, 1,5-proton of NA), 7.70 (d, 4H (3.86H), J = 8.8 Hz, 3,3',5,5' _- proton of OBA), 7.60 (dd, 2H (1.93H), J = 8.8, 2.6 Hz, 3,7-proton of NA). Elemental analysis ( _{C42H20O14 ,} molecular weight 748.61): estimated value C; 67.39%, H; 2.69%, analyzed value C; 67.71%, H; 2.89%. Melting point (DSC): 283°C. From these analytical results, it was confirmed that the product was the desired tetracarboxylic dianhydride represented by the following formula (18).

Comparative Example 3: Preparation and Evaluation of PMDA/4,4'-ODA-Based Polyimide Film
Except for using pyromellitic dianhydride (PMDA) and 4,4'-oxydianiline (4,4'-ODA), which are general-purpose monomers, polymerization was performed in accordance with the method described in Example 3 to obtain a uniform varnish of polyamic acid, which was then cast into a film and thermally imidized to produce a polyimide film, and several film properties were measured. The dielectric constant at 10 GHz was 3.17 and the dielectric loss tangent was 0.01140. Since such a very high dielectric loss tangent value was shown, it can be seen that the conventional polyimide film shown in Comparative Example 3 is not suitable as a heat-resistant insulating film material for high-speed communication FPCs.

[Example 7: Preparation and evaluation of 8-ring TDCA/APAB-based polyesterimide film]
The tetracarboxylic dianhydride described in Example 1, represented by the above formula (15), and 4-aminophenyl 4-aminobenzoate (APAB) as a diamine were polymerized according to the method described in Example 3 to obtain a uniform varnish of polyamic acid, which was then cast into a film and thermally imidized to produce a polyesterimide film, and the film properties were evaluated. This polyesterimide film had very excellent properties in terms of high heat resistance, low water absorption, and low dielectric tangent, similar to the polyesterimide films described in Examples 3 to 6. Table 2 summarizes the physical properties. In Table 2, items that were not evaluated are left blank.

[Example 8: Preparation and evaluation of 8-ring TDCA/ATAB-based polyesterimide film]
The tetracarboxylic dianhydride described in Example 1, represented by the above formula (15), and 4-amino-2-methylphenyl 4-aminobenzoate (ATAB) as a diamine were polymerized according to the method described in Example 3 to obtain a uniform varnish of polyamic acid, which was then cast into a film and thermally imidized to produce a polyesterimide film, and the film properties were evaluated. This polyesterimide film had excellent properties in terms of high heat resistance, low water absorption, and low dielectric tangent, similar to the polyesterimide films described in Examples 3 to 7. Figure 3 shows the infrared absorption spectrum of the thin film sample (film of polyesterimide precursor) before thermal imidization, and Figure 4 shows the infrared absorption spectrum of the thin film sample (polyesterimide film) after thermal imidization.

[Example 9: Preparation and evaluation of 8-ring TCDA/ATAB(70);BAPP(30) copolymer-based polyesterimide film]
The tetracarboxylic dianhydride described in Example 1, represented by the above formula (15), and 4-amino-2-methylphenyl 4-aminobenzoate (ATAB) (70 mol%) and 2,2-bis[4-(4-aminophenoxy)phenyl]propane (BAPP) (30 mol%) as diamines were polymerized according to the method described in Example 3 to obtain a uniform varnish of polyamic acid, which was then cast into a film and thermally imidized to produce a polyesterimide film, and the film properties were evaluated. This polyesterimide film had excellent properties in terms of high heat resistance, low water absorption, and low dielectric tangent, similar to the polyesterimide films described in Examples 3 to 8.

[Example 10: Preparation and evaluation of 6-ring TCDA/p-PDA-based polyesterimide film]
The tetracarboxylic dianhydride described in Example 2a, represented by the above formula (18), and p-phenylenediamine (p-PDA) were polymerized according to the method described in Example 3 to obtain a uniform varnish of polyamic acid, which was then cast into a film and thermally imidized to produce a polyesterimide film, and the film properties were evaluated. This polyesterimide film had excellent properties in terms of high heat resistance, low water absorption, and low dielectric tangent, similar to the polyesterimide films described in Examples 3 to 9.

[Example 11: Preparation and evaluation of 6-ring TCDA/4,4'-ODA based polyesterimide film]
The tetracarboxylic dianhydride represented by formula (18) and described in Example 2a and 4,4'-ODA were polymerized according to the method described in Example 3 to obtain a uniform varnish of polyamic acid, which was then cast into a film and thermally imidized to produce a polyesterimide film, and the film properties were evaluated. This polyesterimide film had excellent properties in terms of high heat resistance, low water absorption, and low dielectric tangent, similar to the polyesterimide films described in Examples 3 to 10.

[Example 12: Preparation and evaluation of 6-ring TCDA/p-PDA (75); 4,4′-ODA (25) copolymer-based polyesterimide film]
The tetracarboxylic dianhydride described in Example 2a, represented by the above formula (18), p-PDA (75 mol%) and 4,4'-ODA (25 mol%) were used to polymerize in accordance with the method described in Example 3 to obtain a uniform varnish of polyamic acid, which was then cast into a film and thermally imidized to produce a polyesterimide film, whose film properties were evaluated. This polyesterimide film had excellent properties in terms of high heat resistance, low water absorption and low dielectric tangent, similar to the polyesterimide films described in Examples 3 to 11.

Claims (9)

The following general formula (1):

It is expressed as
In the general formula (1), Ar ₁ is represented by the following formulas (2) to (6):

It is represented by either
Tetracarboxylic dianhydride. The following general formula (7):

The structural unit represented by
In the general formula (7), Ar ₁ is represented by any one of the formulas (2) to (6), and Ar ₂ is
a divalent aromatic group, a divalent aliphatic group, or a divalent group containing at least one of an aromatic group and an aliphatic group,
Polyesterimide. A film comprising the polyesterimide according to claim 2. The average linear thermal expansion coefficient between 100 and 200°C measured by thermomechanical analysis is 30pp.
4. The film of claim 3, wherein the viscosity is less than or equal to m/K. 4. The film of claim 3, which has a glass transition temperature of 300° C. or more or not detectable as measured by dynamic viscoelastic analysis. The film according to claim 3, which has a water absorption rate of 0.5% or less. The film of claim 3, having a dielectric loss tangent of 0.003 or less at an operating frequency of 10 GHz. A flexible printed wiring board for high-speed communication, comprising the film according to any one of claims 3 to 7. A heat-resistant insulating substrate comprising the film according to any one of claims 3 to 7.