JP7118651B2 - Method for producing film, resin composition and polyamideimide resin - Google Patents

Description

TECHNICAL FIELD The present invention relates to a film containing a polyamideimide resin, a resin composition containing a polyamideimide resin, and a method for producing a polyamideimide resin.

2. Description of the Related Art Currently, image display devices such as liquid crystal display devices and organic EL display devices are widely used not only in televisions but also in various applications such as mobile phones and smart watches. With such expansion of applications, there is a demand for an image display device (flexible display) having a flexible characteristic. 2. Description of the Related Art An image display device is composed of a display element such as a liquid crystal display element or an organic EL display element, and constituent members such as a polarizing plate, a retardation plate and a front plate. All these components need to be flexible in order to achieve a flexible display.

Up to now, glass has been used as the front panel. Glass has high transparency and can exhibit high hardness depending on the type of glass, but it is very rigid and easily broken, so it is difficult to use it as a material for the front panel of a flexible display.

Therefore, utilization of polymeric materials is being studied as a material to replace glass. A front plate made of a polymer material can be expected to be used in various applications because it tends to exhibit flexible characteristics. Various resins are available as flexible resins, one of which is polyamide-imide resin. Polyamideimide resins are used in various applications from the viewpoint of transparency and heat resistance, and various production methods thereof have been studied.

For example, Patent Document 1 discloses a unit structure derived from TFDB (2,2′-bistrifluoromethyl-4,4′-biphenyldiamine), 6FDA (4,4′-(hexafluoroisopropylidene) diphthalic dianhydride, and a resin obtained by copolymerizing a unit structure derived from TPC (tetrephthaloyl chloride; 1,4-benzenedicarbonyl chloride).
Further, Patent Document 2 describes a copolymerized polyamide film having excellent mechanical properties such as pencil hardness.

Japanese Patent Publication No. 2015-521686 Japanese Patent Publication No. 2014-528490

Conventionally, films containing polyamide-imide resins, such as those used as front panels, are required to exhibit high surface hardness as well as high transparency. There was a problem that there was a big difference between

For example, the film described in Patent Document 1 has an average transmittance of 89% or more at a wavelength of 380 to 780 nm, but it has not been clarified whether the film has a sufficiently high surface hardness. Moreover, there is no suggestion of a form suitable for expressing high surface hardness. Although Patent Document 2 describes that the film has a surface pencil hardness of 3H or higher, the evaluation of the pencil hardness may result in different results depending on the illuminance conditions used.

Accordingly, an object of the present invention is to provide a film having a high surface hardness and containing a polyamide-imide resin having a high imidization rate, which is suitably used as a front panel of a flexible display.

In order to solve the above-described problems, the present inventors have made earnest studies on various properties of polyamide-imide resins, focusing on the imidization rate of polyamide-imide resins and the surface hardness of films obtained. As a result, the present inventors have found that the surface hardness of a film can be increased by using a polyamide-imide resin that satisfies specific requirements, and have completed the present invention.

［式（３）中、Ｘは式（３ｅ’）：

〔式（３ｅ’）中、Ｒ^１０～Ｒ^１７は、それぞれ独立に、水素原子、炭素数１～６のアルキル基または炭素数６～１２のアリール基を表し、Ｒ^１０～Ｒ^１７に含まれる水素原子は、それぞれ独立に、ハロゲン原子で置換されていてもよく、＊は結合手を表す〕
を表す］
で表される少なくとも１種の化合物を含む、前記［１］に記載のフィルム。
［３］ジカルボン酸は、式（２）：

［式（２）中、Ｚは式（２ａ）または（２ｂ）：

〔式（２ａ）および式（２ｂ）中、Ｕ^１は、単結合、－Ｏ－、－ＣＨ_２－、－ＣＨ_２－ＣＨ_２－、－ＣＨ（ＣＨ_３）－、－Ｃ（ＣＨ_３）_２－、－Ｃ（ＣＦ_３）_２－、－Ａｒ－、－ＳＯ_２－、－ＣＯ－、－Ｏ－Ａｒ－Ｏ－、－Ａｒ－Ｏ－Ａｒ－、－Ａｒ－ＣＨ_２－Ａｒ－、－Ａｒ－Ｃ（ＣＨ_３）_２－Ａｒ－または－Ａｒ－ＳＯ_２－Ａｒ－を表し、＊は結合手を表す〕
で表される基を表し、Ｂ^１およびＢ^２は、それぞれ独立して、ＯＨまたはハロゲン原子を表す］
で表される少なくとも１種の化合物を含む、前記［１］または［２］に記載のフィルム。
［４］テトラカルボン酸二無水物は、式（４）：

［式（４）中、Ｙは、式（４ｇ）：

〔式（４ｇ）中、Ｗ^１は、単結合、－Ｃ（ＣＨ_３）_２－または－Ｃ（ＣＦ_３）_２－を表し、＊は結合手を表す〕
を表す］
で表される少なくとも１種の化合物を含む、前記［１］～［３］のいずれかに記載のフィルム。
［５］ポリアミドイミド樹脂Ａはフッ素原子を含む、前記［１］～［４］のいずれかに記載のフィルム。
［６］３以下のＹＩを有する、前記［１］～［５］のいずれかに記載のフィルム。
［７］４，０００ルクスの照度条件下でＡＳＴＭ Ｄ ３３６３に従い測定して３Ｂ以上の鉛筆硬度を有する、前記［１］～［６］のいずれかに記載のフィルム。
［８］ジアミンに由来する構成単位、ジカルボン酸に由来する構成単位、および、テトラカルボン酸二無水物に由来する構成単位を有し、２次元ＮＭＲにより測定して６０％以上のイミド化率を有するポリアミドイミド樹脂Ｂ、および、溶剤を少なくとも含む、樹脂組成物。
［９］ジアミンは、式（３）：

［式（３）中、Ｘは式（３ｅ’）：

〔式（３ｅ’）中、Ｒ^１０～Ｒ^１７は、それぞれ独立に、水素原子、炭素数１～６のアルキル基または炭素数６～１２のアリール基を表し、Ｒ^１０～Ｒ^１７に含まれる水素原子は、それぞれ独立に、ハロゲン原子で置換されていてもよく、＊は結合手を表す〕
を表す］
で表される少なくとも１種の化合物を含む、前記［８］に記載の樹脂組成物。
［１０］ジカルボン酸は、式（２）：

［式（２）中、Ｚは次の式（２ａ）または式（２ｂ）：

〔式（２ａ）および式（２ｂ）中、Ｕ^１は、単結合、－Ｏ－、－ＣＨ_２－、－ＣＨ_２－ＣＨ_２－、－ＣＨ（ＣＨ_３）－、－Ｃ（ＣＨ_３）_２－、－Ｃ（ＣＦ_３）_２－、－Ａｒ－、－ＳＯ_２－、－ＣＯ－、－Ｏ－Ａｒ－Ｏ－、－Ａｒ－Ｏ－Ａｒ－、－Ａｒ－ＣＨ_２－Ａｒ－、－Ａｒ－Ｃ（ＣＨ_３）_２－Ａｒ－または－Ａｒ－ＳＯ_２－Ａｒ－を表し、＊は結合手を表す〕
で表される基を表し、Ｂ^１およびＢ^２は、それぞれ独立して、ＯＨまたはハロゲン原子を表す］
で表される少なくとも１種の化合物を含む、前記［８］または［９］に記載の樹脂組成物。
［１１］テトラカルボン酸二無水物は、式（４）：

［式（４）中、Ｙは、次の式（４ｇ）：

〔式（４ｇ）中、Ｗ^１は、単結合、－Ｃ（ＣＨ_３）_２－または－Ｃ（ＣＦ_３）_２－を表し、＊は結合手を表す〕
を表す］
で表される少なくとも１種の化合物を含む、前記［８］～［１０］のいずれかに記載の樹脂組成物。
［１２］ポリアミドイミド樹脂Ｂはフッ素原子を含む、前記［８］～［１１］のいずれかに記載の樹脂組成物。
［１３］前記［８］～［１２］のいずれかに記載の樹脂組成物の塗膜を乾燥させてなるフィルム。
［１４］（１）ジアミン、ジカルボン酸、および、テトラカルボン酸二無水物を溶剤中で共重合しポリアミドイミド樹脂前駆体を得る工程、および、
（２）ポリアミドイミド樹脂前駆体を少なくとも含む溶液に、脱水剤および第三級アミンを添加し、７０～１２０℃の温度で加熱する工程
を少なくとも含む、ポリアミドイミド樹脂の製造方法であって、工程（１）を開始する際の溶剤中の水分量をｗ（ｐｐｍ）とし、工程（２）における加熱時間をｔ（分）とすると、ｗおよびｔが次の式：

を満たす、製造方法。
［１５］工程（２）において添加される脱水剤のモル量は、工程（１）において添加されるテトラカルボン酸二無水物のモル量の２倍以上である、前記［１４］に記載の製造方法。 That is, the present invention includes the following preferred aspects.
[1] It has at least structural units derived from a diamine, a structural unit derived from a dicarboxylic acid, and a structural unit derived from a tetracarboxylic dianhydride, and has an imidization rate of 95% or more as measured by two-dimensional NMR. A film containing a polyamide-imide resin A having
[2] The diamine has the formula (3):

[In formula (3), X is formula (3e′):

[In formula (3e′), R ¹⁰ to R ¹⁷ each independently represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 12 carbon atoms, and are included in R ¹⁰ to R ¹⁷ Each hydrogen atom may be independently substituted with a halogen atom, and * represents a bond]
represents]
The film according to [1] above, comprising at least one compound represented by
[3] The dicarboxylic acid has the formula (2):

[In formula (2), Z is formula (2a) or (2b):

[In the formulas (2a) and (2b), U ¹ is a single bond, -O-, -CH ₂ -, -CH ₂ -CH ₂ -, -CH(CH ₃ )-, -C(CH ₃ ) _2- , -C(CF ₃ ) ₂ -, -Ar-, -SO ₂ -, -CO-, -O-Ar-O-, -Ar-O-Ar-, -Ar-CH ₂ -Ar-, -Ar-C(CH ₃ ) ₂ -Ar- or -Ar-SO ₂ -Ar-, * represents a bond]
and B ¹ and B ² each independently represent OH or a halogen atom]
The film according to [1] or [2] above, comprising at least one compound represented by
[4] The tetracarboxylic dianhydride has the formula (4):

[In the formula (4), Y is the formula (4g):

[In formula (4g), W ¹ represents a single bond, -C(CH ₃ ) ₂ - or -C(CF ₃ ) ₂ -, and * represents a bond]
represents]
The film according to any one of [1] to [3] above, comprising at least one compound represented by
[5] The film according to any one of [1] to [4], wherein the polyamideimide resin A contains a fluorine atom.
[6] The film according to any one of [1] to [5], which has a YI of 3 or less.
[7] The film of any one of [1] to [6] above, which has a pencil hardness of 3B or more as measured according to ASTM D 3363 under an illumination condition of 4,000 lux.
[8] It has a structural unit derived from a diamine, a structural unit derived from a dicarboxylic acid, and a structural unit derived from a tetracarboxylic dianhydride, and has an imidization rate of 60% or more as measured by two-dimensional NMR. and a resin composition containing at least a solvent.
[9] The diamine has the formula (3):

[In formula (3), X is formula (3e′):

[In formula (3e′), R ¹⁰ to R ¹⁷ each independently represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 12 carbon atoms, and are included in R ¹⁰ to R ¹⁷ Each hydrogen atom may be independently substituted with a halogen atom, and * represents a bond]
represents]
The resin composition according to [8] above, comprising at least one compound represented by:
[10] The dicarboxylic acid has the formula (2):

[In formula (2), Z is the following formula (2a) or formula (2b):

[In the formulas (2a) and (2b), U ¹ is a single bond, -O-, -CH ₂ -, -CH ₂ -CH ₂ -, -CH(CH ₃ )-, -C(CH ₃ ) _2- , -C(CF ₃ ) ₂ -, -Ar-, -SO ₂ -, -CO-, -O-Ar-O-, -Ar-O-Ar-, -Ar-CH ₂ -Ar-, -Ar-C(CH ₃ ) ₂ -Ar- or -Ar-SO ₂ -Ar-, * represents a bond]
and B ¹ and B ² each independently represent OH or a halogen atom]
The resin composition according to [8] or [9] above, comprising at least one compound represented by
[11] The tetracarboxylic dianhydride has the formula (4):

[In formula (4), Y is the following formula (4g):

[In formula (4g), W ¹ represents a single bond, -C(CH ₃ ) ₂ - or -C(CF ₃ ) ₂ -, and * represents a bond]
represents]
The resin composition according to any one of [8] to [10] above, comprising at least one compound represented by
[12] The resin composition according to any one of [8] to [11], wherein the polyamideimide resin B contains a fluorine atom.
[13] A film obtained by drying a coating film of the resin composition according to any one of [8] to [12].
[14] (1) a step of copolymerizing a diamine, a dicarboxylic acid, and a tetracarboxylic dianhydride in a solvent to obtain a polyamideimide resin precursor, and
(2) A method for producing a polyamideimide resin, comprising at least a step of adding a dehydrating agent and a tertiary amine to a solution containing at least a polyamideimide resin precursor and heating at a temperature of 70 to 120 ° C., Let w (ppm) be the water content in the solvent at the start of (1) and t (min) be the heating time in step (2), where w and t are given by the following equation:

A manufacturing method that satisfies
[15] The production according to [14] above, wherein the molar amount of the dehydrating agent added in step (2) is at least twice the molar amount of the tetracarboxylic dianhydride added in step (1). Method.

ADVANTAGE OF THE INVENTION According to this invention, the film which contains the polyamide-imide resin which has a high imidation rate, and is preferably used as a front plate etc. in image display apparatuses etc., and has high surface hardness is obtained.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail. The scope of the present invention is not limited to the embodiments described here, and various modifications can be made without departing from the gist of the present invention.

The film of the present invention contains a polyamideimide resin A having an imidization rate of 95% or more as measured by two-dimensional NMR. When the imidization rate of the polyamideimide resin A is lower than 95%, the polyamideimide tends to have an excessively flexible primary structure, so the surface hardness of the film containing the polyamideimide resin cannot be sufficiently increased. From the viewpoint of the stability of the polyamideimide varnish, the imidization rate of the polyamideimide resin A is preferably 97% or higher, more preferably 98% or higher, and even more preferably 99% or higher. The imidization rate is preferably as high as possible, and the upper limit is not particularly limited, and may be 100% or less. As a method for adjusting the imidization rate of the polyamide-imide resin A to the above range, for example, a method of producing a film using a polyamide resin composition described later and then imidizing it, or a manufacturing method described later. and a method of producing a film using a composition containing a polyamidoimide resin.

The imidization rate of polyamideimide resin A is the ratio of the number of moles of imide bonds in polyamideimide resin A to the value twice the number of moles of structural units derived from tetracarboxylic dianhydride in polyamideimide resin A. and is measured by two-dimensional NMR in this specification. Conventionally, the measurement of the imidization rate of polyamide-imide resins has often been carried out using an infrared spectrum. However, measurements of fully imidized resins are required. However, in order to achieve sufficient imidization, it is necessary to heat the resin at a high temperature, and the decomposition reaction of the resin may occur at the same time during the heating process. I didn't. The present inventors have investigated measuring the imidization rate of a polyamide-imide resin with high accuracy using two-dimensional NMR, and as a result, a polyamide having a predetermined imidization rate measured using two-dimensional NMR It has been found that a film containing imide resin A achieves high surface hardness. The imidization rate of the polyamideimide resin A can be measured by two-dimensional NMR using a predetermined solution obtained by dissolving a film in deuterated dimethylsulfoxide (DMSO-d6) as a measurement sample. The details of the two-dimensional NMR measurement conditions are as shown in Examples.

The pencil hardness (surface hardness) of the film of the present invention is preferably 3B or higher, more preferably 2B or higher, still more preferably B or higher, particularly preferably HB, as measured according to ASTM D 3363 under an illumination condition of 4,000 lux. Above, it is extremely preferably H or more, and most preferably 2H or more. When the pencil hardness of the film of the present invention is at least the above lower limit, it is easy to suppress damage to the surface of the image display device when used as a front plate (window film) of an image display device, and shrinkage and expansion of the film. It is preferable because it is easy to prevent The upper limit of the pencil hardness of the film of the invention is not particularly limited. Pencil hardness is measured according to JIS K5600-5-4:1999. Specifically, the measurement is performed with a load of 100 g and a scanning speed of 60 mm/min, and the evaluation is performed under an illumination condition of a light quantity of 4,000 lux. When evaluating the pencil hardness, the results may vary depending on the illuminance conditions used. Specifically, compared to the pencil hardness measured by evaluating under an illuminance condition of a light amount of 4,000 lux, the pencil hardness measured by evaluating under an illuminance condition of a lower light amount is a lower light amount. Because of this, scratches on the film become less visible, and as a result, there is a high possibility that a pencil hardness higher than the actual value will be obtained. Therefore, the pencil hardness in this specification is a value obtained by evaluating under an illuminance condition of a light amount of 4,000 lux.

The YI value of the film of the invention is preferably 3.5 or less, more preferably 3.0 or less, and even more preferably 2.5 or less. When the YI value is equal to or less than the above upper limit, the visibility of the film can be further enhanced. In addition, the lower limit of the YI value is not particularly limited, and is usually 0 or more. YI value represents the yellowness of the film (Yellow Index: YI value), in accordance with JIS K 7373: 2006, spectrophotometer (manufactured by JASCO Corporation UV-visible near-infrared spectrophotometer V-670 ). Specifically, it is calculated based on the following formula from the tristimulus values (X, Y, Z) obtained by measuring the transmittance for light of 300 to 800 nm. For the measurement, for example, a film with a thickness of 50-55 μm can be used. The thickness of the film of the present invention is not particularly limited as long as the YI value is within the above range, but the thickness range described below is preferably within the above range.

The thickness of the film of the present invention is preferably 20 μm or more, more preferably 30 μm or more, and still more preferably 40 μm or more, from the viewpoint that the pencil hardness also affects the film thickness.
The thickness of the film of the present invention is preferably 300 μm or less, more preferably 200 μm or less, and even more preferably 100 μm or less, from the viewpoint of bending resistance. The thickness is measured using a contact-type digimatic indicator.

The total light transmittance (Tt) of the film of the present invention is preferably 70% or more, more preferably 80% or more, still more preferably 85% or more, particularly preferably 90%, as measured according to JIS K 7105:1981. % or more. When the total light transmittance is equal to or higher than the above lower limit, it is easy to improve visibility when the film of the present invention is incorporated in an image display device. In addition, the upper limit of the total light transmittance of the film of the present invention is usually 100% or less. The total light transmittance is measured in accordance with JIS K 7105:1981 using, for example, a fully automatic direct-reading haze computer HGM-2DP manufactured by Suga Test Instruments Co., Ltd. For the measurement, for example, a film with a thickness of 50-55 μm can be used. The thickness of the film of the present invention is not particularly limited as long as the total light transmittance is within the above range, but the thickness is preferably within the above range.

The elastic modulus of the film of the present invention is preferably 5.9 GPa or less, more preferably 5.5 GPa or less, even more preferably 5.2 GPa or less, particularly preferably 5.0 GPa or less, and most preferably, from the viewpoint of film flexibility. is 4.5 GPa or less. When the elastic modulus is equal to or less than the above upper limit, it is easy to suppress damage to other members due to the film when the flexible display is bent. Although the lower limit of the elastic modulus of the film of the present invention is not particularly limited, it is usually 2.0 GPa or more. The elastic modulus is obtained by measuring the SS curve of a 10 mm wide test piece under the conditions of a chuck distance of 500 mm and a tensile speed of 20 mm/min using, for example, an Autograph AG-IS manufactured by Shimadzu Corporation. can be measured.

From the viewpoint of the bending resistance of the film, the number of times of reciprocating bending of the film is preferably 10,000 times measured until the film breaks under the conditions of R = 1 mm, 135°, a load of 0.75 kgf, and a speed of 175 cpm. Above, more preferably 20,000 times or more, still more preferably 30,000 times or more, particularly preferably 40,000 times or more, most preferably 50,000 times or more. When the number of times of reciprocating folding of the film of the present invention is at least the above lower limit, it is easy to suppress creases that may occur when the film is bent. Although the upper limit of the number of reciprocating bending times of the film of the present invention is not particularly limited, it is generally sufficiently practical if it can be bent about 1,000,000 times or less. The number of times of reciprocating bending can be obtained by using, for example, an MIT folding endurance tester (type 0530) manufactured by Toyo Seiki Seisakusho Co., Ltd., and a test piece cut out from a film having a thickness of 50 μm and a width of 10 mm as a measurement sample.

The polyamide-imide resin A contained in the film of the present invention has at least structural units derived from a diamine, structural units derived from a dicarboxylic acid, and structural units derived from a tetracarboxylic dianhydride.

［式（３）中、Ｘは２価の有機基を表す。］ Polyamideimide resin A contained in the film of the present invention has structural units derived from diamine. Examples of diamines include compounds represented by formula (3). The polyamideimide resin A may have structural units derived from one type of diamine, or may have structural units derived from two or more types of diamines.

[In Formula (3), X represents a divalent organic group. ]

In a preferred embodiment, the polyamideimide resin A contained in the film of the present invention has a structural unit derived from a diamine represented by formula (3), the amount of the structural unit is the total amount of the structural unit contained in the polyamideimide resin A Based on the unit, it is preferably 47.5 mol % or more, more preferably 49.0 mol % or more, and even more preferably 49.5 mol % or more. When the amount of the structural unit derived from the diamine represented by formula (3) is at least the above lower limit, it is easy to obtain a polyamide-imide resin with a high molecular weight, and it is easy to develop high surface hardness. Further, the amount of structural units derived from the diamine represented by formula (3) is preferably 50.5 mol% or less, more preferably 50.0 mol, based on all structural units contained in polyamideimide resin A. % or less, more preferably 49.99 mol % or less. When the amount of structural units derived from the diamine represented by formula (3) is equal to or less than the above upper limit, high transparency and low yellowness are likely to be exhibited.

X in formula (3) represents a divalent organic group, preferably an organic group in which a hydrogen atom in the organic group may be substituted with a hydrocarbon group or a fluorine-substituted hydrocarbon group. The divalent organic group includes groups represented by formulas (3a) to (3i); hydrogen atoms in the groups represented by formulas (3a) to (3i) are methyl groups, fluoro groups, and chloro groups. or a group substituted with a trifluoromethyl group; and a divalent chain hydrocarbon group having 6 or less carbon atoms.

[In the formulas (3a) to (3i),
* represents a bond,
V ¹ to V ³ are each independently a single bond, —O—, —S—, —CH ₂ —, —CH ₂ —CH ₂ —, —CH(CH ₃ )—, —C(CH ₃ ) represents _2- , -C(CF ₃ ) ₂ -, -SO ₂ - or -CO-; ]
One example is V ¹ and V ³ are a single bond, -O- or -S- and V ² is -CH ₂ -, -C(CH ₃ ) ₂ -, -C(CF ₃ ) ₂ - or -SO ₂ -. The bonding positions of V ¹ and V ² to each ring and the bonding positions of V ² and V ³ to each ring are preferably meta-positions or para-positions with respect to each ring. It is more preferable to have

Among the groups represented by formulas (3a) to (3i), from the viewpoint of the surface hardness and flexibility of the film of the present invention, groups represented by formulas (3d) to (3h) are preferable, and the groups represented by formula ( Groups represented by formulas 3e) to (3g) are more preferred. From the viewpoint of the surface hardness and flexibility of the film of the present invention, V ¹ to V ³ are each independently preferably a single bond, —O— or —S—, and a single bond or —O— is more preferable.

Specific examples of diamines represented by formula (3) include aliphatic diamines, aromatic diamines, and mixtures thereof. In the present embodiment, the term "aromatic diamine" refers to a diamine in which an amino group is directly bonded to an aromatic ring, and part of its structure may contain an aliphatic group or other substituents. This aromatic ring may be a single ring or a condensed ring, and examples include, but are not limited to, benzene ring, naphthalene ring, anthracene ring and fluorene ring. Among these, a benzene ring is preferred. The term "aliphatic diamine" refers to a diamine in which an amino group is directly bonded to an aliphatic group, and part of its structure may contain an aromatic ring or other substituents.

Aliphatic diamines include, for example, acyclic aliphatic diamines such as hexamethylenediamine, as well as 1,3-bis(aminomethyl)cyclohexane, 1,4-bis(aminomethyl)cyclohexane, norbornanediamine and 4,4' - Cycloaliphatic diamines such as diaminodicyclohexylmethane. These can be used alone or in combination of two or more.

Aromatic diamines include, for example, p-phenylenediamine, m-phenylenediamine, 2,4-toluenediamine, m-xylylenediamine, p-xylylenediamine, 1,5-diaminonaphthalene, and 2,6-diamino aromatic diamines having one aromatic ring such as naphthalene; 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylpropane, 4,4'-diaminodiphenyl ether (ODA), 3,4'-diaminodiphenyl ether, 3,3′-diaminodiphenyl ether, 4,4′-diaminodiphenyl sulfone, 3,4′-diaminodiphenyl sulfone, 3,3′-diaminodiphenyl sulfone, 1,4-bis(4-aminophenoxy)benzene, 1, 3-bis(4-aminophenoxy)benzene, 4,4'-diaminodiphenylsulfone, bis[4-(4-aminophenoxy)phenyl]sulfone, bis[4-(3-aminophenoxy)phenyl]sulfone, 2, 2-bis[4-(4-aminophenoxy)phenyl]propane, 2,2-bis[4-(3-aminophenoxy)phenyl]propane, 2,2′-dimethylbenzidine (MB), 2,2′- Bis(trifluoromethyl)benzidine (TFMB), 4,4′-bis(4-aminophenoxy)biphenyl, 9,9-bis(4-aminophenyl)fluorene, 9,9-bis(4-amino-3- Aromatics having two or more aromatic rings, such as methylphenyl)fluorene, 9,9-bis(4-amino-3-chlorophenyl)fluorene, and 9,9-bis(4-amino-3-fluorophenyl)fluorene diamines. These can be used alone or in combination of two or more.

Preferred aromatic diamines include 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylpropane, 4,4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl ether, 4,4'-diaminodiphenyl sulfone, 3,3′-diaminodiphenyl sulfone, 1,4-bis(4-aminophenoxy)benzene, bis[4-(4-aminophenoxy)phenyl]sulfone, bis[4-(3-aminophenoxy)phenyl]sulfone, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, 2,2-bis[4-(3-aminophenoxy)phenyl]propane, 2,2′-dimethylbenzidine, 2,2′-bis (trifluoromethyl)benzidine, 4,4'-bis(4-aminophenoxy)biphenyl, more preferably 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylpropane, 4,4'-diaminodiphenyl ether , 4,4′-diaminodiphenyl sulfone, 1,4-bis(4-aminophenoxy)benzene, bis[4-(4-aminophenoxy)phenyl]sulfone, 2,2-bis[4-(4-aminophenoxy ) phenyl]propane, 2,2′-dimethylbenzidine, 2,2′-bis(trifluoromethyl)benzidine, 4,4′-bis(4-aminophenoxy)biphenyl. These can be used individually or in combination of 2 or more types.

Among the above diamine compounds, one or more selected from the group consisting of aromatic diamines having a biphenyl structure can be used from the viewpoint of the surface hardness, flexibility, bending resistance, transparency and yellowness of the film of the present invention. preferably selected from the group consisting of 2,2'-dimethylbenzidine, 2,2'-bis(trifluoromethyl)benzidine, 4,4'-bis(4-aminophenoxy)biphenyl and 4,4'-diaminodiphenyl ether It is more preferable to use one or more, and it is even more preferable to use 2,2'-bis(trifluoromethyl)benzidine.

［式（３ｅ’）中、Ｒ^１０～Ｒ^１７は、それぞれ独立に、水素原子、炭素数１～６のアルキル基または炭素数６～１２のアリール基を表し、Ｒ^１０～Ｒ^１７に含まれる水素原子は、それぞれ独立に、ハロゲン原子で置換されていてもよく、＊は結合手を表す。］ From the viewpoint of easily increasing the surface hardness and transparency of the film of the present invention, the polyamideimide resin A may have at least a structural unit derived from a diamine represented by the formula (3e′) where X in the formula (3) is preferable.

[In formula (3e′), R ¹⁰ to R ¹⁷ each independently represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 12 carbon atoms, and are included in R ¹⁰ to R ¹⁷ Each hydrogen atom may be independently substituted with a halogen atom, and * represents a bond. ]

In formula (3e′), R ¹⁰ to R ¹⁷ each independently represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 12 carbon atoms, preferably a hydrogen atom or 1 to 1 carbon atoms. 6 alkyl group, more preferably a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, wherein the hydrogen atoms contained in R ¹⁰ to R ¹⁷ are each independently substituted with a halogen atom; good too. From the viewpoint of surface hardness, flexibility and transparency of the film of the present invention, R ¹⁰ to R ¹⁷ are each independently more preferably a hydrogen atom, a methyl group, a fluoro group, a chloro group or a trifluoromethyl group. , particularly preferably a hydrogen atom or a trifluoromethyl group.

［式（３ｅ”）中、＊は結合手を表す。］ In this embodiment, polyamideimide resin A is derived from a diamine (2,2′-bis(trifluoromethyl)benzidine, also referred to as TFMB) represented by formula (3e″) where X in formula (3) is In this case, the film of the present invention has high transparency, and at the same time, the polyamideimide resin A has a fluorine element-containing skeleton, so that the polyamideimide resin is resistant to the solvent. Since the solubility is improved and the viscosity of the polyamideimide varnish used in producing the film of the present invention can be kept low, the production of the film of the present invention becomes easier.

[In formula (3e″), * represents a bond.]

When the polyamideimide resin A has structural units derived from two or more diamines, X in formula (3) is a structural unit derived from a diamine represented by formula (3e′), preferably formula (3e″). From the viewpoint of improving the transparency and ease of production of the film of the present invention, the amount is preferably 30 mol% or more, more preferably based on the total structural units derived from the diamine contained in the polyamideimide resin A. is 50 mol% or more, more preferably 70 mol% or more.X in formula (3) is represented by formula (3e′), preferably formula (3e″). The upper limit is not particularly limited, and may be 100 mol % or less based on the entire constituent units derived from the diamine contained in the polyamideimide resin A. The ratio of structural units derived from diamines represented by formula (3e′) or (3e″) where X in formula (3) can be measured using, for example, two-dimensional NMR, or the charging ratio of raw materials can also be calculated from

［式（２）中、Ｚは２価の有機基を表し、Ｂ^１およびＢ^２は、それぞれ独立して、ＯＨまたはハロゲン原子、好ましくは塩素原子を表す。］ Polyamideimide resin A contained in the film of the present invention has structural units derived from dicarboxylic acid. When the polyamideimide resin A contained in the film of the present invention has a structural unit derived from a dicarboxylic acid, and is replaced with a structural unit derived from a trivalent or higher carboxylic acid such as 1,3,5-benzenetricarboxylic acid The solubility in solvents tends to be less likely to decrease. The structural unit derived from dicarboxylic acid is preferably a structural unit derived from dicarboxylic acid dichloride. Examples of dicarboxylic acids include compounds represented by formula (2). Polyamideimide resin A may have structural units derived from one type of dicarboxylic acid, or may have structural units derived from two or more types of dicarboxylic acids.

[In formula (2), Z represents a divalent organic group, and B ¹ and B ² each independently represent OH or a halogen atom, preferably a chlorine atom. ]

In the polyamideimide resin A, the amount of structural units derived from the dicarboxylic acid represented by formula (2) is preferably 5 mol% or more, more preferably 15, based on all structural units contained in the polyamideimide resin A. mol % or more, more preferably 20 mol % or more. When the amount of structural units derived from the dicarboxylic acid represented by formula (2) is at least the above lower limit, high surface hardness tends to be exhibited. Further, the amount of structural units derived from the dicarboxylic acid represented by formula (2) is preferably 45 mol% or less, more preferably 40 mol% or less, based on all structural units contained in the polyamideimide resin A. More preferably, it is 30 mol % or less. When the amount of the structural unit derived from the dicarboxylic acid represented by formula (2) is equal to or less than the above upper limit, the film tends to exhibit high flexibility, and the flex resistance tends to be improved.

Z in formula (2) represents a divalent organic group, preferably an organic group in which a hydrogen atom in the organic group may be substituted with a hydrocarbon group or a fluorine-substituted hydrocarbon group. The divalent organic group includes groups represented by formulas (2a) and (2b); hydrogen atoms in the groups represented by formulas (2a) and (2b) are methyl groups, fluoro groups, and chloro groups. or a group substituted with a trifluoromethyl group; and a divalent chain hydrocarbon group having 6 or less carbon atoms.

[In formulas (2a) and (2b),
* represents a bond,
U ¹ is a single bond, —O—, —CH ₂ —, —CH ₂ —CH ₂ —, —CH(CH ₃ )—, —C(CH ₃ ) ₂ —, —C(CF ₃ ) ₂ —, -Ar-, -SO ₂ -, -CO-, -O-Ar-O-, -Ar-O-Ar-, -Ar-CH ₂ -Ar-, -Ar-C(CH ₃ ) ₂ -Ar- or -Ar-SO ₂ -Ar-, preferably a single bond, -O- or -Ar-O-Ar-. Ar represents an arylene group having 6 to 20 carbon atoms in which a hydrogen atom may be substituted with a fluorine atom, and specific examples thereof include a phenylene group. ]

Specific examples of the dicarboxylic acid represented by formula (2) include aromatic dicarboxylic acids, aliphatic dicarboxylic acids and their analogous acid chloride compounds, acid anhydrides, and the like, and two or more of these may be used in combination. You may Specific examples include terephthalic acid; isophthalic acid; naphthalenedicarboxylic acid; 4,4′-biphenyldicarboxylic acid; 3,3′-biphenyldicarboxylic acid; one benzoic acid is a single bond, -CH ₂ -, -C(CH ₃ ) ₂ -, -C(CF ₃ ) ₂ -, -SO ₂ -, -O-, -S-, -NR ⁹ -, -C compounds linked by (=O)- or phenylene groups; and acid chloride compounds thereof. Here, R ⁹ represents a hydrocarbon group having 1 to 12 carbon atoms which may be substituted with a halogen atom.

The dicarboxylic acid represented by formula (2) preferably contains at least one selected from terephthalic acid, 4,4'-biphenyldicarboxylic acid, 4,4'-oxybisbenzoic acid, and acid chloride compounds thereof. is more preferred, and contains at least one selected from the group consisting of terephthaloyl chloride (TPC), 4,4'-biphenyldicarbonyl chloride (BPDOC) and 4,4'-oxybis(benzoyl chloride) (OBBC) more preferably, including 4,4'-oxybis(benzoyl chloride) (OBBC).

［式（１）中、Ｒ^１～Ｒ^８は、それぞれ独立に、水素原子、炭素数１～６のアルキル基または炭素数６～１２のアリール基を表し、Ｒ^１～Ｒ^８に含まれる水素原子は、それぞれ独立に、ハロゲン原子で置換されていてもよく、
Ａは、それぞれ独立に、－Ｏ－、－Ｓ－、－ＣＯ－または－ＮＲ^９－を表し、Ｒ^９はハロゲン原子で置換されていてもよい炭素数１～１２の炭化水素基を表し、
ｍは１～４の整数であり、
＊は結合手を表す。］ From the viewpoint of easily increasing the surface hardness and transparency of the film of the present invention, the polyamide-imide resin A preferably has at least a structural unit represented by formula (1) for Z in formula (2).

[In formula (1), R ¹ to R ⁸ each independently represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 12 carbon atoms, and the hydrogen contained in R ¹ to R ⁸ each atom may be independently substituted with a halogen atom,
A each independently represents -O-, -S-, -CO- or -NR ⁹ -, R ⁹ represents a hydrocarbon group having 1 to 12 carbon atoms which may be substituted with a halogen atom,
m is an integer from 1 to 4,
* represents a bond. ]

Symbols in formula (1) are described below.
A each independently represents -O-, -S-, -CO- or -NR ⁹ -, where R ⁹ is a hydrocarbon group having 1 to 12 carbon atoms optionally substituted with a halogen atom represents From the viewpoint of the flexibility of the film of the present invention, each A preferably independently represents -O- or -S-, more preferably -O-.
R ¹ to R ⁸ each independently represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 12 carbon atoms. From the viewpoint of the flexibility and surface hardness of the film of the present invention, each of R ¹ to R ⁸ independently represents preferably a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, more preferably a hydrogen atom or a It represents 1 to 3 alkyl groups, more preferably a hydrogen atom. Here, hydrogen atoms contained in R ¹ to R ⁸ may each independently be substituted with a halogen atom.
m is an integer in the range of 1 to 4, preferably an integer in the range of 1 to 3, more preferably 1 or 2, still more preferably 1 from the viewpoint of raw material availability. When m is within the above range, the availability of raw materials is favorable, and the flexibility of the film of the present invention is likely to be enhanced.

In a preferred embodiment of the present invention, formula (1) is a structural unit represented by formula (1'). In this case, the film of the present invention tends to exhibit high surface hardness, low elastic modulus, and high flexibility.

Polyamideimide resin A contained in the film of the present invention in a preferred embodiment having a structural unit represented by formula (1) or formula (1'), the amount of the structural unit is contained in the polyamideimide resin A It is preferably 3 mol % or more, more preferably 5 mol % or more, even more preferably 10 mol % or more, and particularly preferably 20 mol % or more, based on all structural units. When the amount of the structural unit represented by formula (1) or formula (1') is at least the above lower limit, the resin film tends to exhibit high flexibility, and thus its flex resistance is likely to be improved. Further, the amount of structural units represented by formula (1) or formula (1') is preferably 45 mol% or less, more preferably 40 mol% or less, based on all structural units contained in polyamideimide resin A. , more preferably 30 mol % or less. When the amount of the structural unit represented by formula (1) or formula (1') is equal to or less than the above upper limit, the glass transition temperature of the resin film tends to be improved.

As the polyamide-imide resin A, from the viewpoint of easily increasing the surface hardness, elastic modulus and flexibility of the film of the present invention, Z in formula (2) is a structural unit derived from a dicarboxylic acid represented by formula (1). It is preferable to have at least When the polyamideimide resin has a structural unit derived from two or more dicarboxylic acids, and Z in formula (2) has a structural unit derived from a dicarboxylic acid represented by formula (1), the formula (1 ) is based on the entire structural units derived from dicarboxylic acid contained in the polyamideimide resin A, from the viewpoint of surface hardness, elastic modulus and flexibility of the film, preferably is 5 mol % or more, more preferably 7 mol % or more, still more preferably 9 mol % or more, and particularly preferably 11 mol % or more. The upper limit of the amount of structural units derived from the dicarboxylic acid represented by Z in formula (2) is not particularly limited, and based on the entire structural units derived from the dicarboxylic acid contained in polyamideimide resin A 100 mol % or less. The ratio of structural units derived from the dicarboxylic acid represented by formula (1) where Z in formula (2) can be measured using, for example, two-dimensional NMR, or can be calculated from the feed ratio of raw materials. can.

［式（４）中、Ｙは、４価の有機基を表す。］ Polyamideimide resin A contained in the film of the present invention has structural units derived from tetracarboxylic dianhydride. Examples of tetracarboxylic dianhydrides include compounds represented by Formula (4). The polyamideimide resin A may have a structural unit derived from one type of tetracarboxylic dianhydride, or may have a structural unit derived from two or more types of tetracarboxylic dianhydride. good.

[In Formula (4), Y represents a tetravalent organic group. ]

In the polyamideimide resin A contained in the film of the present invention, the amount of structural units derived from the tetracarboxylic dianhydride represented by formula (4) is based on all structural units contained in the polyamideimide resin A, It is preferably 5 mol % or more, more preferably 10 mol % or more, still more preferably 20 mol % or more. When the amount of the structural unit derived from the tetracarboxylic dianhydride represented by the formula (4) is at least the above lower limit, the ratio of the structural unit derived from the dicarboxylic acid can be suppressed, and the Tg is 370°C or less. of polyamidoimide resin is easily obtained. Further, the amount of structural units derived from the tetracarboxylic dianhydride represented by formula (4) is based on all structural units contained in the polyamideimide resin A, preferably 45 mol% or less, more preferably 40 mol % or less, more preferably 30 mol % or less. When the amount of structural units derived from the tetracarboxylic dianhydride represented by formula (4) is equal to or less than the above upper limit, the proportion of structural units derived from dicarboxylic acid can be increased, and high surface hardness can be obtained. Cheap.

Y in formula (4) represents a tetravalent organic group, preferably an organic group in which a hydrogen atom in the organic group may be substituted with a hydrocarbon group or a fluorine-substituted hydrocarbon group. The organic group is preferably a hydrocarbon group or an organic group optionally substituted with a fluorine-substituted hydrocarbon group. The organic group is preferably a tetravalent organic group having 4 to 40 carbon atoms. The hydrocarbon group and fluorine-substituted hydrocarbon group preferably have 1 to 8 carbon atoms. The tetravalent organic group includes groups represented by formulas (4a) to (4j); hydrogen atoms in the groups represented by formulas (4a) to (4j) are methyl groups, fluoro groups, and chloro groups. or a group substituted with a trifluoromethyl group; and a tetravalent chain hydrocarbon group having 6 or less carbon atoms.

[In formulas (4a) to (4j),
* represents a bond,
W ¹ is a single bond, —O—, —CH ₂ —, —CH ₂ —CH ₂ —, —CH(CH ₃ )—, —C(CH ₃ ) ₂ —, —C(CF ₃ ) ₂ —, -Ar-, -SO ₂ -, -CO-, -O-Ar-O-, -Ar-O-Ar-, -Ar-CH ₂ -Ar-, -Ar-C(CH ₃ ) ₂ -Ar- or -Ar-SO ₂ -Ar-. Ar represents an arylene group having 6 to 20 carbon atoms in which a hydrogen atom may be substituted with a fluorine atom, and specific examples thereof include a phenylene group. ]

Among the groups represented by formulas (4a) to (4j), from the viewpoint of the surface hardness and flexibility of the film of the present invention, the groups represented by formulas (4g), (4i) and (4j) is preferred, and a group represented by formula (4g) is more preferred. W ¹ is a single bond, —O—, —CH ₂ —, —CH ₂ —CH ₂ —, —CH(CH ₃ )—, —C, from the viewpoint of surface hardness and flexibility of the film of the present invention. (CH ₃ ) ₂ - or -C(CF ₃ ) ₂ - is preferred, a single bond, -O-, -CH ₂ -, -CH(CH ₃ )-, -C(CH ₃ ) ₂ - or It is more preferably -C(CF ₃ ) ₂ -, more preferably a single bond, -C(CH ₃ ) ₂ - or -C(CF ₃ ) ₂ -, a single bond or -C(CF ₃ ) _2- is particularly preferred.

Specific examples of the tetracarboxylic dianhydrides represented by formula (4) include aromatic tetracarboxylic dianhydrides and aliphatic tetracarboxylic dianhydrides. One type of tetracarboxylic dianhydride may be used, or two or more types may be used in combination.

Specific examples of aromatic tetracarboxylic dianhydrides include non-condensed polycyclic aromatic tetracarboxylic dianhydrides, monocyclic aromatic tetracarboxylic dianhydrides and condensed polycyclic aromatic tetracarboxylic dianhydrides. Carboxylic acid dianhydrides are mentioned. Non-fused polycyclic aromatic tetracarboxylic dianhydrides include 4,4′-oxydiphthalic dianhydride (OPDA), 3,3′,4,4′-benzophenonetetracarboxylic dianhydride, 2 ,2′,3,3′-benzophenonetetracarboxylic dianhydride, 3,3′,4,4′-biphenyltetracarboxylic dianhydride (BPDA), 2,2′,3,3′-biphenyltetracarboxylic dianhydride Carboxylic acid dianhydride, 3,3′,4,4′-diphenylsulfonetetracarboxylic acid dianhydride, 2,2-bis(3,4-dicarboxyphenyl)propane dianhydride, 2,2-bis( 2,3-dicarboxyphenyl)propane dianhydride, 2,2-bis(3,4-dicarboxyphenoxyphenyl)propane dianhydride, 4,4′-(hexafluoroisopropylidene)diphthalic dianhydride, 1,2-bis(2,3-dicarboxyphenyl)ethane dianhydride, 1,1-bis(2,3-dicarboxyphenyl)ethane dianhydride, 1,2-bis(3,4-dicarboxy Phenyl)ethane dianhydride, 1,1-bis(3,4-dicarboxyphenyl)ethane dianhydride, bis(3,4-dicarboxyphenyl)methane dianhydride, bis(2,3-dicarboxyphenyl) ) methane dianhydride, 4,4′-(p-phenylenedioxy)diphthalic dianhydride, 4,4′-(m-phenylenedioxy)diphthalic dianhydride. Further, the monocyclic aromatic tetracarboxylic dianhydride includes 1,2,4,5-benzenetetracarboxylic dianhydride. The condensed polycyclic aromatic tetracarboxylic dianhydride includes 2,3,6,7-naphthalenetetracarboxylic dianhydride. These can be used alone or in combination of two or more.

Among these, preferably 4,4'-oxydiphthalic dianhydride, 3,3',4,4'-benzophenonetetracarboxylic dianhydride, 2,2',3,3'-benzophenonetetracarboxylic dianhydride anhydride, 3,3′,4,4′-biphenyltetracarboxylic dianhydride, 2,2′,3,3′-biphenyltetracarboxylic dianhydride, 3,3′,4,4′-diphenyl Sulfonetetracarboxylic dianhydride, 2,2-bis(3,4-dicarboxyphenyl)propane dianhydride, 2,2-bis(2,3-dicarboxyphenyl)propane dianhydride, 2,2- Bis(3,4-dicarboxyphenoxyphenyl)propane dianhydride, 4,4'-(hexafluoroisopropylidene)diphthalic dianhydride (6FDA), 1,2-bis(2,3-dicarboxyphenyl) Ethane dianhydride, 1,1-bis(2,3-dicarboxyphenyl)ethane dianhydride, 1,2-bis(3,4-dicarboxyphenyl)ethane dianhydride, 1,1-bis(3 ,4-dicarboxyphenyl)ethane dianhydride, bis(3,4-dicarboxyphenyl)methane dianhydride, bis(2,3-dicarboxyphenyl)methane dianhydride, 4,4′-(p- phenylenedioxy)diphthalic dianhydride and 4,4'-(m-phenylenedioxy)diphthalic dianhydride. More preferably 4,4'-oxydiphthalic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 2,2',3,3'-biphenyltetracarboxylic dianhydride, 4,4′-(hexafluoroisopropylidene)diphthalic dianhydride (6FDA), bis(3,4-dicarboxyphenyl)methane dianhydride and 4,4′-(p-phenylenedioxy)diphthalic dianhydride Anhydrides are mentioned. These can be used individually or in combination of 2 or more types.

Aliphatic tetracarboxylic dianhydrides include cyclic or acyclic aliphatic tetracarboxylic dianhydrides. The cyclic aliphatic tetracarboxylic dianhydride is a tetracarboxylic dianhydride having an alicyclic hydrocarbon structure, and specific examples thereof include 1,2,4,5-cyclohexanetetracarboxylic dianhydride. 1,2,3,4-cyclobutanetetracarboxylic dianhydride, cycloalkanetetracarboxylic dianhydride such as 1,2,3,4-cyclopentanetetracarboxylic dianhydride, bicyclo[2.2 .2] oct-7-ene-2,3,5,6-tetracarboxylic dianhydride, dicyclohexyl 3,3'-4,4'-tetracarboxylic dianhydride and positional isomers thereof . These can be used alone or in combination of two or more. Specific examples of the acyclic aliphatic tetracarboxylic dianhydride include 1,2,3,4-butanetetracarboxylic dianhydride and 1,2,3,4-pentanetetracarboxylic dianhydride. and these can be used alone or in combination of two or more. A cyclic aliphatic tetracarboxylic dianhydride and an acyclic aliphatic tetracarboxylic dianhydride may also be used in combination.

Among the above tetracarboxylic dianhydrides, 4,4'-oxydiphthalic dianhydride, 3,3 from the viewpoint of easily increasing the surface hardness, flexibility, bending resistance, and transparency of the film and easily reducing the yellowness. ',4,4'-benzophenonetetracarboxylic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 2,2',3,3'-biphenyltetracarboxylic dianhydride , 3,3′,4,4′-diphenylsulfonetetracarboxylic dianhydride, 2,2-bis(3,4-dicarboxyphenyl)propane dianhydride, 4,4′-(hexafluoroisopropylidene) Diphthalic dianhydrides, and mixtures thereof are preferred, 3,3′,4,4′-biphenyltetracarboxylic dianhydride (BPDA) and 4,4′-(hexafluoroisopropylidene)diphthalic dianhydride (6FDA), and mixtures thereof are more preferred, and 4,4'-(hexafluoroisopropylidene)diphthalic dianhydride is even more preferred.

［式（４ｇ’）中、Ｒ^１８～Ｒ^２５は、それぞれ独立に、水素原子、炭素数１～６のアルキル基または炭素数６～１２のアリール基を表し、Ｒ^１８～Ｒ^２５に含まれる水素原子は、それぞれ独立に、ハロゲン原子で置換されていてもよく、＊は結合手を表す。］ The polyamideimide resin A preferably has at least a structural unit derived from a tetracarboxylic dianhydride represented by the formula (4g') where Y in the formula (4) is. In this case, the film of the present invention has high transparency, and at the same time, the polyamideimide resin A has a highly flexible skeleton, so that the solubility of the polyamideimide resin in a solvent is improved, and the film of the present invention is produced. Since the viscosity of the polyamide-imide varnish used in this case can be kept low, the film of the present invention can be easily produced.

[In formula (4g′), R ¹⁸ to R ²⁵ each independently represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 12 carbon atoms, and are included in R ¹⁸ to R ²⁵ Each hydrogen atom may be independently substituted with a halogen atom, and * represents a bond. ]

In formula (4g′), R ¹⁸ to R ²⁵ each independently represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 12 carbon atoms, preferably a hydrogen atom or 6 alkyl group, more preferably a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, wherein the hydrogen atoms contained in R ¹⁸ to R ²⁵ are each independently substituted with a halogen atom; good too. From the viewpoint of the surface hardness and flexibility of the film of the present invention, R ¹⁸ to R ²⁵ are each independently more preferably a hydrogen atom, a methyl group, a fluoro group, a chloro group or a trifluoromethyl group, particularly preferably is a hydrogen atom or a trifluoromethyl group.

［式（４ｇ”）中、＊は結合手を表す。］ In the preferred embodiment described above, the polyamideimide resin A preferably has at least a structural unit derived from a tetracarboxylic dianhydride represented by the formula (4g″) where Y in the formula (4). In the case, the film of the present invention has high transparency, and at the same time, the polyamideimide resin A has a fluorine element-containing skeleton, so that the solubility of the polyamideimide resin in a solvent is improved, and the film of the present invention is produced. Since the viscosity of the polyamide-imide varnish used for coating can be kept low, the film of the present invention can be easily produced.

[In formula (4g″), * represents a bond.]

When the polyamideimide resin A has structural units derived from two or more tetracarboxylic dianhydrides, Y in formula (4) is a tetracarboxylic acid represented by formula (4g′), preferably formula (4g″). The amount of structural units derived from carboxylic acid dianhydride, from the viewpoint of improving the transparency and ease of production of the film, to the entire structural unit derived from the tetracarboxylic acid dianhydride contained in the polyamideimide resin A based on, preferably 50 mol% or more, more preferably 60 mol% or more, still more preferably 70 mol% or more. Y in formula (4) is formula (4g'), preferably formula (4g'') The upper limit of the amount of structural units derived from the tetracarboxylic dianhydride represented is not particularly limited, based on the total structural units derived from the tetracarboxylic dianhydride contained in the polyamideimide resin 100 mol% or less I wish I had. The ratio of structural units derived from the diamine represented by formula (4g′) or (4g″) where X in formula (4) can be measured using, for example, two-dimensional NMR, or It can also be calculated from the ratio.

Polyamideimide resin A contained in the film of the present invention may further have structural units derived from tricarboxylic acid. Examples of tricarboxylic acids include aromatic tricarboxylic acids, aliphatic tricarboxylic acids and their analogues such as acid chloride compounds and acid anhydrides. One type of tricarboxylic acid may be used, or two or more types may be used in combination. Specific examples include anhydride of 1,2,4-benzenetricarboxylic acid; 2,3,6-naphthalenetricarboxylic acid-2,3-anhydride; a single bond between phthalic anhydride and benzoic acid; , —CH ₂ —, —C(CH ₃ ) ₂ —, —C(CF ₃ ) ₂ —, —SO ₂ —, or compounds linked by a phenylene group.

［式（５）中、ＸおよびＹは前記と同義である。］

［式（６）中、ＸおよびＺは前記と同義である。］
式（５）および式（６）中のＸ、ＹおよびＺは、それぞれ、式（３）中のＸ、式（４）中のＹおよび式（２）中のＺと同義であり、式（２）～式（４）中のＸ、ＹおよびＺに関して上記に述べた好ましい記載が、式（５）および式（６）中のＸ、ＹおよびＺについても同様にあてはまる。式（５）で表される構成単位は、通常、ジアミンおよびテトラカルボン酸に由来する構成単位であり、式（６）で表される構成単位は、通常、ジアミンおよびジカルボン酸に由来する構成単位である。 In a preferred embodiment of the present invention, the polyamideimide resin A contained in the film of the present invention includes dicarboxylic acids (dicarboxylic acid analogues such as acid chloride), diamines and tetracarboxylic acids (acid chlorides, tetracarboxylic dianhydrides (tetracarboxylic acid analogues such as tricarboxylic acid analogues) and, optionally, tricarboxylic acid (tricarboxylic acid compound analogues such as acid chloride compounds and tricarboxylic anhydrides). In this aspect, the polyamideimide resin A has a structural unit represented by formula (5) and a structural unit represented by formula (6) below.

[In Formula (5), X and Y have the same definitions as above. ]

[In formula (6), X and Z have the same definitions as above. ]
X, Y and Z in formula (5) and formula (6) are respectively synonymous with X in formula (3), Y in formula (4) and Z in formula (2); 2) The preferred statements made above for X, Y and Z in formulas (4) also apply to X, Y and Z in formulas (5) and (6). The structural unit represented by formula (5) is usually a structural unit derived from diamine and tetracarboxylic acid, and the structural unit represented by formula (6) is usually a structural unit derived from diamine and dicarboxylic acid. is.

［式（７）中、Ｘ^１は２価の有機基を表し、Ｙ^１は４価の有機基を表す。］

［式（８）中、Ｘ^２は２価の有機基を表し、Ｙ^２は３価の有機基を表す。］ In a preferred embodiment of the present invention, the polyamideimide resin A contained in the film of the present invention further comprises a structural unit represented by formula (7) and/or a structural unit represented by formula (8) below. may have.

[In Formula (7), X ¹ represents a divalent organic group, and Y ¹ represents a tetravalent organic group. ]

[In Formula (8), X2 represents a ^divalent organic group, and ^Y2 represents a trivalent organic group. ]

In formula (7), each Y ¹ is independently a tetravalent organic group, preferably a hydrogen atom in the organic group may be substituted with a hydrocarbon group or a fluorine-substituted hydrocarbon group. It is an organic group. Examples of Y ¹ include groups represented by formulas (4a) to (4j) and tetravalent chain hydrocarbon groups having 6 or less carbon atoms. Polyamideimide resin A may have one structural unit represented by formula (7), or may be represented by two or more types of formula (7) different from each other in Y ¹ and / or X ¹ You may have a structural unit.

In formula (8), each Y ² is independently a trivalent organic group, preferably a hydrogen atom in the organic group may be substituted with a hydrocarbon group or a fluorine-substituted hydrocarbon group It is an organic group. Examples of Y ² include a group in which one of the bonds of the groups represented by formulas (4a) to (4j) is replaced with a hydrogen atom, and a trivalent chain hydrocarbon group having 6 or less carbon atoms. be done. Polyamideimide resin A may have one structural unit represented by formula (8), or may be represented by two or more types of formula (7) different from each other in Y ² and / or X ² You may have a structural unit.

In formulas (7) and (8), X ¹ and X ² are each independently a divalent organic group, preferably a hydrocarbon group or a hydrocarbon in which a hydrogen atom in the organic group is substituted with fluorine. It is an organic group optionally substituted with a group. X ¹ and X ² are groups represented by formulas (3a) to (3i); hydrogen atoms in the groups represented by formulas (3a) to (3i) are methyl groups, fluoro groups, and chloro groups. or a group substituted with a trifluoromethyl group; and a chain hydrocarbon group having 6 or less carbon atoms.

In a preferred embodiment of the present invention, the polyamideimide resin A contained in the film of the present invention is a structural unit represented by formula (5) and formula (6), and optionally formula (7) and / or formula ( 8) consists of structural units represented by In this aspect, from the viewpoint of easily increasing the flexibility and surface hardness of the film, the amount of the structural units represented by the formulas (5) and (6) contained in the polyamideimide resin A is the amount of the formula (5) and the formula ( 6), and optionally 80% or more, more preferably 90% or more, and even more preferably 95% or more, based on all structural units represented by formulas (7) and (8). Note that the upper limit of the amount of the structural units represented by the formulas (5) and (6) contained in the polyamideimide resin A is the formulas (5) and (6), and optionally the formulas (7) and Based on all structural units represented by formula (8), it is usually 100% or less. The above ratio can be measured using, for example, two-dimensional NMR, or can be calculated from the charging ratio of raw materials.

Polyamideimide resin A contained in the film of the present invention, glass transition temperature Tg calculated by tan δ in dynamic viscoelasticity measurement (DMA measurement) is preferably less than 380 ° C., more preferably 379 ° C. or less, more preferably 378° C. or less, for example 370° C. or less. When the glass transition temperature Tg of the polyamideimide resin A is less than the above upper limit or the above upper limit or less, the film of the present invention tends to exhibit high surface hardness, while the elastic modulus tends to decrease and flexibility tends to increase. . Although the lower limit of the glass transition temperature Tg is not particularly limited, it is usually 300° C. or higher. Specifically, the method of calculating the glass transition temperature from tan δ in dynamic viscoelasticity measurement (DMA measurement) can be carried out as in Examples.

The weight average molecular weight (Mw) of the polyamideimide resin A contained in the film of the present invention is preferably 5,000 or more, more preferably 10,000 or more, still more preferably 50,000 or more, and particularly preferably 70,000 or more. is preferably 800,000 or less, more preferably 600,000 or less, still more preferably 500,000 or less, and particularly preferably 450,000 or less. When the weight average molecular weight (Mw) of the polyamide-imide resin A is at least the above lower limit, the bending resistance of the film of the present invention can be easily increased. When the weight average molecular weight (Mw) of the polyamideimide resin A is the above upper limit or less, the solubility of the polyamideimide resin in a solvent is improved, and the viscosity of the polyamideimide varnish used in producing the film of the present invention is reduced. Since it can be suppressed low, it becomes easy to manufacture the film of the present invention. In addition, since the film can be easily stretched, the processability is good. The weight average molecular weight (Mw) can be determined by, for example, GPC measurement and standard polystyrene conversion, and specifically can be determined by the method described in Examples.

The polyamide-imide resin A contained in the film of the present invention preferably contains halogen atoms, more preferably fluorine atoms. Specific examples of fluorine-containing substituents include a fluoro group and a trifluoromethyl group. When the polyamide-imide resin A contains a halogen atom, the yellowness index (YI value) of the film of the present invention can be easily reduced, and high flexibility and bending resistance can be easily achieved at the same time. From the viewpoints of reduction in yellowness (improvement in transparency), reduction in water absorption, and flexibility of the film of the present invention, the halogen atom is preferably a fluorine atom. From the above viewpoint, the polyamideimide resin A preferably has at least structural units derived from a fluorine atom-containing diamine and/or a fluorine atom-containing tetracarboxylic dianhydride.

The content of halogen atoms in the polyamideimide resin A is the mass of the polyamideimide resin A contained in the film of the present invention from the viewpoint of reducing yellowness (improving transparency), reducing water absorption, and suppressing deformation of the film. based on, preferably 1 to 40% by mass, more preferably 3 to 35% by mass, even more preferably 5 to 32% by mass.

From the viewpoint of improving the visibility and quality of the film of the present invention, the film of the present invention may contain an additive having a light absorbing function in addition to the polyamide-imide resin. Additives having a light absorption function include, for example, ultraviolet absorbers, bluing agents, and the like. The additive having a light absorption function is preferably selected from the group consisting of an ultraviolet absorber and a bluing agent, since the visibility and quality of the film of the present invention can be easily improved. The film of the present invention may contain one type of additive having a light absorbing function, or may contain two or more types of additives having a light absorbing function. Here, when additives having a light absorption function such as ultraviolet absorbers and bluing agents are added to films containing conventional polyamideimide resins, these additives have low heat resistance. In the process of heating the containing film under high temperature conditions, there is a problem that decomposition or the like occurs and the quality of the film deteriorates. Therefore, for example, it was necessary to add these additives to a layer separate from the layer containing the polyamide-imide resin and bond it to the polyamide-imide film. For example, when producing a film using the resin composition of the present invention or a composition containing a polyamideimide resin obtained by the production method of the present invention, the imidization rate of the polyamideimide resin contained in the resin composition is increased in advance. can be kept Therefore, even when the film is produced under relatively low-temperature heating conditions, the imidization rate can be increased, and a sufficiently high surface hardness can be achieved. Therefore, even when an additive having a light absorption function is added to the same layer as the layer containing the polyamide-imide resin, decomposition of these additives can be suppressed, and deterioration of film quality can be suppressed.

As the ultraviolet absorber, it may be used by appropriately selecting from those commonly used as ultraviolet absorbers in the field of resin materials. The ultraviolet absorber may contain a compound that absorbs light with a wavelength of 400 nm or less. Examples of the ultraviolet absorber include at least one compound selected from the group consisting of benzophenone-based compounds, salicylate-based compounds, benzotriazole-based compounds, and triazine-based compounds. When the film of the present invention contains an ultraviolet absorber, deterioration of the polyamide-imide resin is suppressed, so the visibility of the film can be enhanced. In addition, in this specification, a "system compound" refers to the derivative of the compound to which the said "system compound" is attached. For example, a "benzophenone-based compound" refers to a compound having benzophenone as a parent skeleton and a substituent attached to the benzophenone.

When the film of the present invention contains an ultraviolet absorber, the amount of the ultraviolet absorber to be added may be appropriately selected depending on the type of ultraviolet absorber used. % or more, more preferably 2 mass % or more, still more preferably 3 mass % or more, preferably 10 mass % or less, more preferably 8 mass % or less, still more preferably 6 mass % or less. A suitable addition amount varies depending on the ultraviolet absorber used, but adjusting the addition amount so that the light transmittance at 400 nm is about 20 to 60% makes it easy to increase the light resistance of the film of the present invention, and transparency. It is preferable because it is easy to obtain a film having a high

The bluing agent may be appropriately selected from those commonly used as bluing agents in the field of resin materials. A bluing agent is an additive (dye, pigment) that absorbs light in a wavelength region such as orange to yellow in the visible light region and adjusts the hue. inorganic dyes and pigments, and organic dyes and pigments such as phthalocyanine bluing agents and condensed polycyclic bluing agents. The bluing agent is not particularly limited, but from the viewpoint of heat resistance, light resistance and solubility, a condensed polycyclic bluing agent is preferable, and an anthraquinone bluing agent is more preferable. From the viewpoint of heat resistance, the bluing agent preferably has a thermal decomposition temperature of 200°C or higher. Examples of condensed polycyclic bluing agents include anthraquinone bluing agents, indigo bluing agents, and phthalocyanine bluing agents.

When the film of the present invention contains a bluing agent, the amount of bluing agent to be added may be appropriately selected according to the type of bluing agent used. 01% by mass or more, more preferably 0.02% by mass or more, still more preferably 0.03% by mass or more, preferably 1.0% by mass or less, more preferably 0.5% by mass or less, further preferably 0 .2% by mass or less.

The film of the present invention may further contain an inorganic material such as inorganic particles in addition to the polyamide-imide resin. Examples of inorganic materials include inorganic particles such as titania particles, alumina particles, zirconia particles and silica particles, and silicon compounds such as quaternary alkoxysilanes such as tetraethyl orthosilicate. From the viewpoint of the stability of the polyamideimide varnish, the inorganic material is preferably inorganic particles, particularly silica particles. The inorganic particles may be bonded together by molecules having siloxane bonds.

The average primary particle size of the inorganic particles is preferably 10 to 100 nm, more preferably 20 to 80 nm, from the viewpoints of film transparency, mechanical properties, and inhibition of aggregation of the inorganic particles. In the present invention, the average primary particle diameter can be determined by measuring 10 directional diameters with a transmission electron microscope (TEM) and calculating their average value.

When the film of the present invention contains an inorganic material, the content of the inorganic material in the film is preferably 0 to 90% by mass, more preferably 0 to 60% by mass, more preferably 0% by mass, based on the total mass of the film. ~40% by mass. When the content of the inorganic material is within the above range, it tends to be easy to achieve both transparency and mechanical properties of the film.

The film of the invention may contain other additives. Other additives include, for example, antioxidants, release agents, stabilizers, flame retardants, pH adjusters, silica dispersants, lubricants, thickeners and leveling agents. When the film of the present invention contains other additives, the content of the other additives is preferably 0% by mass or more and 20% by mass or less, more preferably 0% by mass, based on the mass of the film of the present invention. It is more than 10 mass % or less.

(Layer structure)
The layer structure of the film of the present invention is not particularly limited, and may be a single layer or multiple layers of two or more layers. When the film of the present invention further contains an additive such as an additive having a light absorption function, the additive and the polyamideimide resin are combined into one layer from the viewpoint of thinning of the image display device and economic efficiency. It is preferable to contain. In this case, the film of the present invention is more preferably a single layer containing the additive and the polyamideimide resin, or a laminate having at least a layer containing the additive and the polyamideimide resin. From the viewpoint of impact resistance, the film of the present invention preferably has a multilayer structure of two or more layers including at least a layer containing a polyamide-imide resin. When the film of the present invention further contains an additive such as an additive having a light absorption function, it is a laminate having at least a layer containing the additive and a polyamideimide resin, or a layer containing the additive, It may be a laminate having at least a layer containing a polyamide-imide resin.

The film of the present invention may be a polyamide-imide laminate obtained by laminating one or more functional layers on the above layer. Examples of functional layers include layers having various functions such as a hard coat layer, an ultraviolet absorbing layer, an adhesive layer, a refractive index adjusting layer, and a primer layer. Films of the present invention may comprise one or more functional layers. Also, one functional layer may have multiple functions. For example, a film having a multilayer structure may be obtained by forming the functional layer on a film containing a polyamide-imide resin.

The present invention has a structural unit derived from a diamine, a structural unit derived from a dicarboxylic acid, and a structural unit derived from a tetracarboxylic dianhydride, and has an imidization rate of 60% or more as measured by two-dimensional NMR. and a resin composition comprising at least a solvent. The film of the present invention containing the polyamideimide resin A is produced, for example, using the resin composition of the present invention containing at least the polyamideimide resin B and a solvent.

The resin composition of the present invention contains a polyamideimide resin B having an imidization rate of 60% or more as measured by two-dimensional NMR. The resin composition of the present invention is a composition used for producing a film containing a polyamideimide resin, and contains a polyamideimide resin B having a high imidization rate as described above, so that the finally obtained film can sufficiently increase the imidization rate of the polyamide-imide resin contained in, and as a result, a polyamide-imide film having a sufficiently high surface hardness can be obtained. When the imidization rate of the polyamideimide resin contained in the resin composition is lower than 60%, the polyamideimide tends to have an excessively flexible primary structure, so that the surface hardness of the finally obtained polyamideimide film is sufficiently increased. cannot be raised to From the viewpoint of surface hardness, the imidization rate of polyamide-imide resin B is preferably 80% or more, more preferably 90% or more, and even more preferably 95% or more. The imidization rate is preferably as high as possible, and the upper limit is not particularly limited, and may be 100% or less.

The imidization rate of the polyamideimide resin B is the ratio of the number of moles of imide bonds in the polyamideimide resin B to the value twice the number of moles of the structural units derived from the tetracarboxylic dianhydride in the polyamideimide resin B. and is measured by two-dimensional NMR in this specification. The imidization rate of the polyamideimide resin B is obtained by adding a poor solvent to the resin composition (varnish) and depositing and drying the polyamideimide resin B by a reprecipitation method, and dissolving it in deuterated dimethyl sulfoxide (DMSO-d6). Using the predetermined solution obtained by the method as a measurement sample, it can be measured using two-dimensional NMR.

Examples of the poor solvent include alcoholic solvents, water, saturated hydrocarbon solvents and aromatic solvents, preferably alcoholic solvents and water. Alcohol solvents include methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, 1-isobutanol, 1-heptanol, 2-heptanol, 3-heptanol, 1-hexanol and 2-hexanol. , 3-hexanol, ethylene glycol and glycerin, preferably methanol, ethanol, 1-propanol and 2-propanol, more preferably methanol and ethanol. Two or more of these poor solvents may be mixed.

The imidization rate is represented by Formula (9).

For polyimide resins or polyimide films, the molar ratio can be obtained by appropriately integrating the signal derived from the repeating unit having an amic acid and the signal derived from the repeating unit having an imide bond on the ¹ H-NMR spectrum. can be obtained, and the imidization rate can be obtained by applying the formula (9). Here, an amic acid contains an amide bond and a carboxyl group, which are precursors of an imide bond.
Polyamideimide resin or polyamideimide film is obtained by appropriately integrating signals derived from repeating units having an amic acid and repeating units having an imide bond on a two-dimensional NMR spectrum using DMSO-d6 as a solvent. By doing so, the imidization rate can be obtained. Examples of the conversion method include applying a correlation equation between the imidization rate obtained by the ¹ H-NMR spectrum and the value.

Conventionally known or commonly used techniques are applied to obtain the imidization rate with high accuracy. Such techniques include, for example, increasing the S/N ratio, which is the signal-to-noise ratio, and integrating the obtained two-dimensional NMR spectrum with high accuracy. The S/N ratio is preferably 6 or more in order to obtain the imidization rate more accurately. Methods for increasing the S/N ratio include, for example, increasing the sample concentration, increasing the number of times of integration, and using a highly sensitive NMR measurement device. High-sensitivity NMR measurement devices include, for example, NMR devices with stronger magnetic fields and NMR devices using cryoprobes. Further, as a method for accurately integrating a two-dimensional NMR spectrum, for example, performing phase correction and performing baseline correction can be mentioned. Furthermore, when the signals on the two-dimensional NMR spectrum derived from a structure different from the repeating unit having an amic acid and the repeating unit having an imide bond overlap, integration is performed without including the intensity of the signal with high accuracy. The imidization rate can be obtained.

Polyamideimide resin B, glass transition temperature Tg calculated by tan δ in dynamic viscoelasticity measurement (DMA measurement) is preferably less than 380 ° C., more preferably 379 ° C. or less, more preferably 378 ° C. or less, for example 370 ° C. It is below. When the glass transition temperature Tg of the polyamideimide resin B is less than the above upper limit or the above upper limit or less, the film obtained using the resin composition of the present invention tends to exhibit high surface hardness, and at the same time, the elastic modulus is increased. Easy to lower and easy to increase flexibility. Although the lower limit of the glass transition temperature Tg is not particularly limited, it is usually 300° C. or higher. Specifically, the method of calculating the glass transition temperature from tan δ in dynamic viscoelasticity measurement (DMA measurement) can be carried out as in Examples.

The weight average molecular weight (Mw) of the polyamideimide resin B contained in the film of the present invention is preferably 5,000 or more, more preferably 10,000 or more, still more preferably 50,000 or more, and particularly preferably 70,000 or more. is preferably 800,000 or less, more preferably 600,000 or less, still more preferably 500,000 or less, and particularly preferably 450,000 or less. When the weight average molecular weight (Mw) of the polyamide-imide resin B is at least the above lower limit, the bending resistance of the film obtained using the resin composition of the present invention can be easily increased. When the weight average molecular weight (Mw) of the polyamideimide resin B is the above upper limit or less, the solubility of the polyamideimide resin in a solvent is improved, and the viscosity of the resin composition of the present invention can be suppressed low. Easier to manufacture films. In addition, since the film can be easily stretched, the processability is good. The weight average molecular weight (Mw) can be determined by, for example, GPC measurement and standard polystyrene conversion, and specifically can be determined by the method described in Examples.

The polyamideimide resin B contained in the resin composition of the present invention has structural units derived from a diamine, structural units derived from a dicarboxylic acid, and structural units derived from a tetracarboxylic dianhydride. With respect to specific examples and preferred embodiments of diamines, dicarboxylic acids and tetracarboxylic dianhydrides, the above descriptions regarding polyamideimide resin A apply similarly. Similarly to the polyamideimide resin A, the polyamideimide resin B contained in the resin composition of the present invention may further have structural units derived from a tricarboxylic acid. As for the tricarboxylic acid, the above description regarding the polyamide-imide resin A applies similarly.

［式（５）中、ＸおよびＹは前記と同義である。］

［式（６）中、ＸおよびＺは前記と同義である。］
式（５）および式（６）中のＸ、ＹおよびＺは、それぞれ、式（３）中のＸ、式（４）中のＹおよび式（２）中のＺと同義であり、式（２）～式（４）中のＸ、ＹおよびＺに関して上記に述べた好ましい記載が、式（５）および式（６）中のＸ、ＹおよびＺについても同様にあてはまる。式（５）で表される構成単位は、通常、ジアミンおよびテトラカルボン酸に由来する構成単位であり、式（６）で表される構成単位は、通常、ジアミンおよびジカルボン酸に由来する構成単位である。 In a preferred embodiment of the present invention, the polyamideimide resin B contained in the resin composition of the present invention comprises dicarboxylic acid (dicarboxylic acid analog such as acid chloride), diamine and tetracarboxylic acid (acid chloride, tetracarboxylic acid di It is a condensation-type polymer that is a polycondensation product of a tetracarboxylic acid analogue such as an anhydride) and optionally a tricarboxylic acid (a tricarboxylic acid compound analogue such as an acid chloride compound or tricarboxylic anhydride). . In this embodiment, the polyamideimide resin B, like the polyamideimide resin A, has a structural unit represented by formula (5) and a structural unit represented by formula (6).

[In Formula (5), X and Y have the same definitions as above. ]

[In formula (6), X and Z have the same definitions as above. ]
X, Y and Z in formula (5) and formula (6) are respectively synonymous with X in formula (3), Y in formula (4) and Z in formula (2); 2) The preferred statements made above for X, Y and Z in formulas (4) also apply to X, Y and Z in formulas (5) and (6). The structural unit represented by formula (5) is usually a structural unit derived from diamine and tetracarboxylic acid, and the structural unit represented by formula (6) is usually a structural unit derived from diamine and dicarboxylic acid. is.

［式（７）中、Ｘ^１は２価の有機基を表し、Ｙ^１は４価の有機基を表す。］

［式（８）中、Ｘ^２は２価の有機基を表し、Ｙ^２は３価の有機基を表す。］ In a preferred embodiment of the present invention, the polyamideimide resin B contained in the resin composition of the present invention is further a structural unit represented by the formula (7) and / or a structure represented by the following formula (8) May have units.

[In Formula (7), X ¹ represents a divalent organic group, and Y ¹ represents a tetravalent organic group. ]

[In Formula (8), X2 represents a ^divalent organic group, and ^Y2 represents a trivalent organic group. ]

In formula (7), each Y ¹ is independently a tetravalent organic group, preferably a hydrogen atom in the organic group may be substituted with a hydrocarbon group or a fluorine-substituted hydrocarbon group. It is an organic group. Examples of Y ¹ include groups represented by formulas (4a) to (4j) and tetravalent chain hydrocarbon groups having 6 or less carbon atoms. Polyamideimide resin B may have one structural unit represented by formula (7), or may be represented by two or more types of formula (7) different from each other in Y ¹ and / or X ¹ You may have a structural unit.

In formula (8), each Y ² is independently a trivalent organic group, preferably a hydrogen atom in the organic group may be substituted with a hydrocarbon group or a fluorine-substituted hydrocarbon group It is an organic group. The organic group is preferably a trivalent organic group having 4 to 40 carbon atoms. The hydrocarbon group and fluorine-substituted hydrocarbon group preferably have 1 to 8 carbon atoms. Also, the number of carbon atoms in the organic group is preferably 4 to 40. Y ² is a group in which one of the bonds of the groups represented by the above formulas (4a) to (4j) is replaced with a hydrogen atom, and a trivalent chain hydrocarbon group having 6 or less carbon atoms. are exemplified. Polyamideimide resin B may have a structural unit represented by one type of formula (8), or represented by two or more types of formula (7) different from each other in Y ² and / or X ² You may have a structural unit. Examples of W ¹ in the formulas are the same as those of W ¹ in the description of Y ¹ .

In formulas (7) and (8), X ¹ and X ² are each independently a divalent organic group, preferably a hydrocarbon group or a hydrocarbon in which a hydrogen atom in the organic group is substituted with fluorine. It is an organic group optionally substituted with a group. The organic group is preferably a divalent organic group having 4 to 40 carbon atoms. The hydrocarbon group and fluorine-substituted hydrocarbon group preferably have 1 to 8 carbon atoms. Also, the number of carbon atoms in the organic group is preferably 4 to 40. X ¹ and X ² are groups represented by formulas (3a) to (3i); hydrogen atoms in the groups represented by formulas (3a) to (3i) are methyl groups, fluoro groups, and chloro groups. or a group substituted with a trifluoromethyl group; and a chain hydrocarbon group having 6 or less carbon atoms.

In a preferred embodiment of the present invention, the polyamideimide resin B contained in the resin composition of the present invention is a structural unit represented by formula (5) and formula (6), and optionally formula (7) and / or It consists of structural units represented by the formula (8). In this aspect, from the viewpoint of easily increasing the flexibility and surface hardness of the film, the amount of the structural units represented by the formulas (5) and (6) contained in the polyamideimide resin B is the formula (5) and the formula ( 6), and optionally 80% or more, more preferably 90% or more, and even more preferably 95% or more, based on all structural units represented by formulas (7) and (8). The upper limit of the amount of structural units represented by formulas (5) and (6) contained in the polyamideimide resin B is formulas (5) and (6), and optionally formulas (7) and Based on all structural units represented by formula (8), it is usually 100% or less. The above ratio can be measured using, for example, two-dimensional NMR, or can be calculated from the charging ratio of raw materials.

The polyamideimide resin B contained in the resin composition of the present invention also preferably contains a halogen atom like the polyamideimide resin A, and more preferably contains a fluorine atom. Specific examples of fluorine-containing substituents include a fluoro group and a trifluoromethyl group. By including a halogen atom in the polyamide-imide resin B, it is easy to reduce the yellowness (YI value) of the film obtained using the resin composition of the present invention, and to achieve both high flexibility and bending resistance. The halogen atom is preferably a fluorine atom from the viewpoints of reduction in yellowness (improvement in transparency) of the film, reduction in water absorption, and flexibility. From the above viewpoint, the polyamideimide resin B preferably has at least structural units derived from a fluorine atom-containing diamine and/or a fluorine atom-containing tetracarboxylic dianhydride.

The content of halogen atoms in the polyamideimide resin B is the polyamideimide resin B contained in the resin composition of the present invention from the viewpoint of reducing yellowness (improving transparency), reducing water absorption, and suppressing film deformation. based on the weight of, preferably 1 to 40% by weight, more preferably 3 to 35% by weight, even more preferably 5 to 32% by weight.

The solvent contained in the resin composition of the present invention is not particularly limited as long as it can dissolve the polyamideimide resin B. Examples of such solvents include amide solvents such as N,N-dimethylacetamide (DMAc) and N,N-dimethylformamide; lactone solvents such as γ-butyrolactone and γ-valerolactone; dimethylsulfone, dimethylsulfoxide, sulfolane, and the like. carbonate-based solvents such as ethylene carbonate and propylene carbonate; and combinations thereof (mixed solvents). Among these solvents, amide-based solvents or lactone-based solvents are preferred, and solvents containing dimethylacetamide are more preferred. Further, the polyamide-imide varnish may contain water, an alcohol solvent, a ketone solvent, an acyclic ester solvent, an ether solvent, and the like. The resin composition of the present invention may further contain additives that the film of the present invention described above may contain.

Next, the method for producing the polyamide-imide resin A contained in the film of the present invention and the method for producing the polyamide-imide resin B contained in the resin composition of the present invention will be described below. Polyamideimide resin A and polyamideimide resin B are, for example, the above-mentioned dicarboxylic acid, diamine and tetracarboxylic acid as main raw materials, and optionally further with the above-described tricarboxylic acid Copolymerization (polycondensation) It can be manufactured by

The method for producing the polyamideimide resin A contained in the film of the present invention and the polyamideimide resin B contained in the resin composition of the present invention is not particularly limited as long as the polyamideimide resin having the above properties is obtained.
(1) a step of copolymerizing a diamine, a dicarboxylic acid, and a tetracarboxylic dianhydride in a solvent to obtain a polyamideimide resin precursor;
(2) It can be produced by a method including at least a step of adding a dehydrating agent and a tertiary amine to a solution containing at least a polyamideimide resin precursor and heating at a temperature of 70 to 120°C.

The present invention also provides
(1) a step of copolymerizing a diamine, a dicarboxylic acid, and a tetracarboxylic dianhydride in a solvent to obtain a polyamideimide resin precursor;
(2) including at least a step of adding a dehydrating agent and a tertiary amine to a solution containing at least a polyamideimide resin precursor and heating at a temperature of 70 to 120 ° C., in a solvent when starting step (1) Also provided is a method for producing a polyamideimide resin, wherein w and t satisfy the following formula, where w (ppm) is the water content of and t (minutes) is the heating time in step (2).

The polyamideimide resin obtained by the production method of the present invention may be, for example, polyamideimide resin A or polyamideimide resin B, and the above description of polyamideimide resin A and polyamideimide resin B applies similarly. It is also possible to obtain the resin composition of the present invention by the production method of the present invention and to produce the film of the present invention using the resin composition.

In this aspect, the polyamideimide resin obtained by the production method of the present invention and the polyamideimide resin B contained in the resin composition of the present invention are the same resin. Further, the polyamideimide resin B contained in the resin composition of the present invention and the polyamideimide resin A contained in the film of the present invention may be the same resin in terms of the imidization rate and the structural units of the resin. , resins having different imidization ratios.

In step (1) above, a diamine, a dicarboxylic acid, and a tetracarboxylic dianhydride are copolymerized in a solvent to obtain a polyamideimide resin precursor. The reaction temperature for copolymerization is not particularly limited, but is, for example, 50 to 350°C. The reaction time is also not particularly limited, but is, for example, about 30 minutes to 10 hours. If desired, the reaction may be conducted under conditions of inert atmosphere or reduced pressure. Examples of the solvent used in step (1) include the solvents contained in the resin composition of the present invention described above.

In step (1), an imidization catalyst may be used. Examples of imidization catalysts include aliphatic amines such as tripropylamine, dibutylpropylamine, ethyldibutylamine; N-ethylpiperidine, N-propylpiperidine, N-butylpyrrolidine, N-butylpiperidine, and N-propylhexahydro Alicyclic amines (monocyclic) such as azepine; azabicyclo[2.2.1]heptane, azabicyclo[3.2.1]octane, azabicyclo[2.2.2]octane, and azabicyclo[3.2. 2] Alicyclic amines (polycyclic) such as nonane; Aromatic amines such as 4-dimethylpyridine, 2,4,6-trimethylpyridine, 3,4-cyclopentenopyridine, 5,6,7,8-tetrahydroisoquinoline, and isoquinoline.

Next, in step (2), a dehydrating agent and a tertiary amine are added to the solution containing at least the polyamide-imide resin precursor and heated at a temperature of 70 to 120°C. In this step, the imidization of the polyamide-imide resin precursor proceeds. The heating time in this step may be appropriately selected according to the scale of the reaction and the type and amount of reagents used, but is usually 1 to 48 hours. Finally yellowness is reduced, from the viewpoint of easily obtaining a polyamideimide film having a high surface hardness, in the process, the imidization rate of the polyamideimide resin contained in the polyamideimide resin composition is preferably 60% or more. , more preferably 80% or more, still more preferably 95% or more, step (2) may be performed.

The dehydrating agent used in step (2) is a substance capable of promoting copolymerization of diamine, dicarboxylic acid, and tetracarboxylic dianhydride in a solvent, which is a polycondensation reaction involving dehydration. Examples of dehydrating agents include acetic anhydride, propionic anhydride, isobutyric anhydride, pivalic anhydride, butyric anhydride and isovaleric anhydride. The dehydrating agent is preferably selected from the group consisting of acetic anhydride and propionic anhydride, more preferably acetic anhydride.

The tertiary amine used in step (2) is a substance that acts as an imidization catalyst. Examples of tertiary amines include the aforementioned aromatic amines and aliphatic amines. Tertiary amines are preferably selected from the group consisting of triethylamine, tripropylamine, N-ethylpiperidine, N-propylpiperidine, pyridine, methylpyridine, ethylpyridine, dimethylpyridine and isoquinoline.

１／ｔ（ｗ＋１６７）は、好ましくは５．０以下、より好ましくは４．０以下、さらに好ましくは３．０以下である。ポリアミドイミド樹脂を製造するためのジアミン、ジカルボン酸、および、テトラカルボン酸二無水物を溶剤中で共重合は、脱水を伴う重縮合反応である。そのため、反応系中に存在する水の量を少なくしたり、加熱時間を調整したりすることによって、効率的に重縮合反応（特にイミド化反応）を進行させることができ、その結果、得られるポリアミドイミド樹脂におけるイミド化率を高めることができる。したがって、本発明の上記製造方法によれば、従来よりも高いイミド化率を有するポリアミドイミド樹脂を製造することができる。なお、従来知られている製造方法では、ポリアミドイミド樹脂のイミド化率を十分に高くすることは困難である。そのため、比較的低いイミド化率を有するポリアミドイミド樹脂を含むポリアミドイミドワニスを用いてフィルムを作製し、このフィルムを高温条件下で加熱してイミド化を進行させる工程が行われている。しかし、上記に述べたように、フィルムの状態で加熱を行い、イミド化率を高める場合には、十分に高いイミド化率が達成できず、十分な表面硬度が得られず、また、加熱条件によってはポリアミドイミド樹脂のイミド化率のばらつきが生じ、イミド化率が安定しないなどの問題があった。本発明の製造方法によれば、ポリアミドイミド樹脂のイミド化率を、フィルムに加工する前の合成段階で十分に高めやすく、上記のような問題が解決される。 In the production method of the present invention, w (ppm) is the water content in the solvent at the start of step (1), and t (minutes) is the heating time in step (2). meet.

1/t(w+167) is preferably 5.0 or less, more preferably 4.0 or less, and even more preferably 3.0 or less. Copolymerization of diamine, dicarboxylic acid, and tetracarboxylic dianhydride in a solvent for producing a polyamide-imide resin is a polycondensation reaction accompanied by dehydration. Therefore, by reducing the amount of water present in the reaction system or adjusting the heating time, the polycondensation reaction (especially the imidization reaction) can be efficiently advanced, and as a result, the obtained It is possible to increase the imidization rate in the polyamide-imide resin. Therefore, according to the production method of the present invention, it is possible to produce a polyamide-imide resin having a higher imidization rate than conventionally. It should be noted that it is difficult to sufficiently increase the imidization rate of the polyamide-imide resin by the conventionally known production methods. Therefore, a process is performed in which a film is produced using a polyamide-imide varnish containing a polyamide-imide resin having a relatively low imidization rate, and the film is heated under high-temperature conditions to promote imidization. However, as described above, when heating is performed in the state of a film to increase the imidization rate, a sufficiently high imidization rate cannot be achieved, and a sufficient surface hardness cannot be obtained. In some cases, the imidization rate of the polyamide-imide resin varies, and there is a problem that the imidization rate is not stable. According to the production method of the present invention, the imidization rate of the polyamide-imide resin can be sufficiently increased in the synthesis stage before being processed into a film, and the above problems can be solved.

The production method of the present invention is not particularly limited as long as it includes at least steps (1) and (2). As a method for producing a resin composition containing a polyamideimide resin obtained by the production method of the present invention, for example, a mixture containing a polyamideimide resin obtained in steps (1) and (2) is further added with a solvent and necessary By adding additives according to and stirring, a resin composition containing at least a polyamideimide resin and a solvent (hereinafter, also referred to as "polyamideimide varnish") may be produced, and the step (1) and A poor solvent is added to the mixture containing the polyamideimide resin obtained in step (2) to precipitate the polyamideimide resin by a reprecipitation method, dried and taken out as a precipitate, and the taken out polyamideimide resin precipitate is dissolved in a solvent. to obtain a resin composition containing at least a polyamide-imide resin and a solvent.

The film of the present invention, for example, (1) a step of applying the polyamideimide resin composition obtained as described above to a support, and
(2-1) a step of peeling off the coating film of the composition from the support after drying, or
(2-2) It can be produced by a production method including at least a step of peeling the coating film of the composition from the support after drying, and a step of heating the peeled film. Thus, the film of the present invention is obtained by drying the coating film of the polyamide-imide resin composition obtained as described above.

For example, by a known roll-to-roll or batch method, a coating film of polyamideimide varnish is formed by applying polyamideimide varnish on a support such as a resin substrate, SUS belt, or glass substrate. can be done. Examples of supports include PET film, PEN film, polyimide film, polyamideimide film, and the like. Among them, PET film, PEN film, polyimide film, and other polyamideimide films are preferable from the viewpoint of excellent heat resistance. A PET film is more preferable from the viewpoint of adhesion with the film of the present invention and cost.

Next, in step (2-1) or step (2-2), the coating film of polyamide-imide varnish is dried and peeled off from the support after drying. Drying of the coating film can be carried out at a temperature of preferably 50 to 240°C, more preferably 200 to 240°C. Drying of the coating may be carried out under conditions of an inert atmosphere or reduced pressure, if desired. The film of the present invention can be obtained by peeling the coating from the support after drying. In addition, as described in step (2-2), for example, a step of further heating the peeled film may be performed for the purpose of further increasing the surface hardness (pencil hardness) of the film of the present invention. The heating temperature is preferably 240° C. or lower.

At least one surface of the film produced as described above may be subjected to a surface treatment step. Surface treatments include, for example, UV ozone treatment, plasma treatment, and corona discharge treatment.

In a preferred embodiment of the present invention, the film of the present invention contains an additive such as an additive having a light absorption function, when the film of the present invention contains a polyamideimide resin and the additive in the same layer, such The layer can be produced in the same manner as described above by using a polyamideimide varnish obtained by adding the additive to a composition (polyamideimide varnish) containing at least a polyamideimide resin and a solvent. In a preferred embodiment of the present invention in which an additive such as an additive having a light absorption function and a polyamide-imide resin are contained in one layer, it is preferable to use an additive having a thermal decomposition temperature of at least 200° C. or higher.

The film of the invention may further comprise functional layers. Examples of functional layers include layers having various functions such as a hard coat layer, an ultraviolet absorbing layer, an adhesive layer, a refractive index adjusting layer, and a primer layer. Films of the present invention may comprise one or more functional layers. Also, one functional layer may have multiple functions.

The hard coat layer is preferably arranged on the viewer side surface of the film. The hard coat layer may have a single layer structure or a multilayer structure. The hard coat layer comprises a hard coat layer resin, and examples of the hard coat layer resin include acrylic resins, epoxy resins, urethane resins, benzyl chloride resins, vinyl resins, silicone resins, or mixtures thereof. UV curable, electron beam curable, or thermosetting resins such as resins may be used. In particular, the hard coat layer preferably contains an acrylic resin from the viewpoint of mechanical properties such as surface hardness and from an industrial point of view. In a preferred embodiment of the present invention, since the film of the present invention has a high surface hardness, it has sufficient surface hardness to be used in image display devices and the like even without a hard coat layer. Therefore, when the film of the present invention further has a hard coat layer, it is possible to further increase the surface hardness of the film.

The ultraviolet absorbing layer is a layer having a function of absorbing ultraviolet rays. It is composed of dispersed ultraviolet absorbers. By providing an ultraviolet absorption layer as a functional layer, it is possible to easily suppress a change in yellowness due to light irradiation.

The adhesive layer is a layer having an adhesive function, and has a function of adhering the film of the present invention to another member. Commonly known materials can be used as the material for forming the adhesive layer. For example, a thermosetting resin composition or a photocurable resin composition can be used.

The adhesive layer may be composed of a resin composition containing a component having a polymerizable functional group. In this case, strong adhesion can be realized by further polymerizing the resin composition that constitutes the adhesive layer after the film is adhered to another member. The adhesive strength between the film of the present invention and the adhesive layer may be 0.1 N/cm or more, or 0.5 N/cm or more.

The adhesive layer may contain a thermosetting resin composition or a photocurable resin composition as a material. In this case, the resin composition can be polymerized and cured by supplying energy afterward.

The adhesive layer may be a layer composed of an adhesive called Pressure Sensitive Adhesive (PSA), which is adhered to an object by pressing. The pressure-sensitive adhesive may be a pressure-sensitive adhesive that is "a substance that has adhesiveness at room temperature and adheres to the adherend with light pressure" (JIS K6800), and "a specific component is a protective coating (microcapsule) It may be a capsule-type adhesive that is "adhesive that can maintain stability until the coating is destroyed by appropriate means (pressure, heat, etc.)" (JIS K6800).

The hue-adjusting layer is a layer having a hue-adjusting function and capable of adjusting the hue of the film of the present invention to a desired hue. The hue adjusting layer is, for example, a layer containing a resin and a colorant. Examples of the coloring agent include inorganic pigments such as titanium oxide, zinc oxide, red iron oxide, titanium oxide-based calcined pigments, ultramarine blue, cobalt aluminate, and carbon black; azo-based compounds, quinacridone-based compounds, anthraquinone-based compounds, Organic pigments such as perylene compounds, isoindolinone compounds, phthalocyanine compounds, quinophthalone compounds, threne compounds, and diketopyrrolopyrrole compounds; extender pigments such as barium sulfate and calcium carbonate; and basic dyes, Dyes such as acid dyes and mordant dyes can be mentioned.

The refractive index adjusting layer is a layer having a function of adjusting the refractive index, has a different refractive index from the layer containing the polyamide-imide resin A in the film of the present invention, and imparts a predetermined refractive index to the film of the present invention. It is a layer that can The refractive index adjusting layer may be, for example, a resin layer containing an appropriately selected resin and optionally a pigment, or may be a metal thin film.

Pigments that adjust the refractive index include, for example, silicon oxide, aluminum oxide, antimony oxide, tin oxide, titanium oxide, zirconium oxide, and tantalum oxide. The average primary particle size of the pigment may be 0.1 μm or less. By setting the average primary particle size of the pigment to 0.1 μm or less, it is possible to prevent diffused reflection of light passing through the refractive index adjusting layer and to prevent a decrease in transparency.

Examples of metals used for the refractive index adjusting layer include metals such as titanium oxide, tantalum oxide, zirconium oxide, zinc oxide, tin oxide, silicon oxide, indium oxide, titanium oxynitride, titanium nitride, silicon oxynitride, and silicon nitride. Oxides or metal nitrides may be mentioned.

The film of the present invention is an optical film useful as, for example, the front panel of an image display device, particularly the front panel (window film) of a flexible display. The film of the present invention can be arranged as a front plate on the viewing side surface of an image display device, particularly a flexible display. This front panel has a function of protecting the image display element in the flexible display.

Image display devices include televisions, smartphones, mobile phones, car navigation systems, tablet PCs, portable game machines, electronic paper, indicators, bulletin boards, watches, and wearable devices such as smart watches. Flexible displays include image display devices such as those described above that have flexible characteristics.

The present invention will be described in more detail below with reference to examples. Unless otherwise specified, "%" and "parts" in the examples mean % by mass and parts by mass. First, the evaluation method will be explained.

<Measurement of weight average molecular weight (Mw)>
The weight-average molecular weight (Mw) of the polyamide-imide resin was determined by gel permeation chromatography (GPC) and converted to standard polystyrene. Specific measurement conditions were as follows.
(1) Pretreatment method DMF eluent (10 mM lithium bromide solution) was added to the obtained polyamideimide resin so that the concentration was 2 mg / mL, heated at 80 ° C. for 30 minutes with stirring, cooled, and then dried. A solution obtained by filtering using a membrane filter with an opening of 0.45 μm was used as a measurement solution.
(2) Measurement conditions Column: TSKgel SuperAWM-H × 2 + SuperAW2500 × 1 (6.0 mm ID × 150 mm × 3) (both manufactured by Tosoh Corporation)
Eluent: DMF (with 10 mM lithium bromide added)
Flow rate: 1.0 mL/min.
Detector: RI detector Column temperature: 40°C
Injection volume: 100 μL
Molecular weight standard: standard polystyrene

<Measurement of glass transition temperature (Tg)>
Using DMA Q800 manufactured by TA Instruments, measurements were made under the following samples and conditions to obtain a tan δ curve, which is the ratio of loss modulus to storage modulus. The Tg of the polyamide-imide resin was calculated from the highest peak of the tan δ curve.
Sample (film): length 5-15 mm, width 5 mm
Experimental mode: DMA Multi-Frequency-Strain
Experiment mode detailed conditions:
(1) Clamp: Tension: Film
(2) Amplitude: 5 μm
(3) Frequency: 10 Hz (no change in all temperature intervals)
(4) Preload Force: 0.01N
(5) Force Track: 125N
Temperature conditions: (1) Range of temperature rise: Normal temperature to 400°C, (2) Rate of temperature rise: 5°C/min Main collected data: (1) Storage modulus (E'), (2) Loss modulus (Loss modulus, E"), (3) tan δ (E"/E')

<Measurement of imidization rate>
The imidization ratios of the polyimide resins and polyamideimide resins used in Examples and Comparative Examples were measured by NMR and calculated using the signal derived from the partial structure shown in formula (10). A method for calculating the imidization ratio from the measurement conditions and the obtained results is as follows.

(Method for preparing measurement sample)
Polyamideimide resin B:
A resin composition (varnish) containing at least a solvent is added with a large excess amount of methanol as a poor solvent, and the resin is precipitated and dried by a reprecipitation method, and the resin is dissolved in deuterated dimethyl sulfoxide (DMSO-d6). A 2% by mass solution was prepared as a measurement sample.
Polyamideimide resin A:
A measurement sample was prepared by dissolving a resin-containing film in deuterated dimethyl sulfoxide (DMSO-d6) to obtain a 2% by mass solution.

(NMR measurement conditions)
Measuring device: 600 MHz NMR device AVANCE600 manufactured by Bruker
Sample temperature: 303K
Measurement method: 1H-NMR, HSQC

（ポリアミドイミド樹脂のイミド化率の算出方法）
ポリイミド樹脂を含む溶液を測定試料として得られたＨＳＱＣスペクトルにおいて、式（１０ＸＸＸ）中のプロトン（Ｃ）に由来するシグナルの積分値をＩｎｔ_Ｃ、プロトン（Ｄ）およびプロトン（Ｅ）に由来するシグナルの積分値の平均値をＩｎｔ_ＤＥとした。これらの値から、以下の式（ＮＭＲ－２）によりβ値を求めた。

次に、複数のポリイミド樹脂について、式（ＮＭＲ－２）によるβ値および式（ＮＭＲ－１）によるイミド化率（％）を求め、この結果から以下の相関式（ＮＭＲ－３）を得た。

そして、ポリアミドイミド樹脂を含む溶液を測定試料として得られたＨＳＱＣスペクトルにおいて、上記と同様にして式（ＮＭＲ－２）によりβ値を求めた。このβ値を上記の相関式（ＮＭＲ－３）へ代入することにより、ポリアミドイミド樹脂のイミド化率（％）を得た。 (Calculation method of imidization rate of polyimide resin)
In the ¹ H-NMR spectrum obtained by using a solution containing a polyimide resin as a measurement sample, Int _A is the integral value of the signal derived from proton (A) in formula (10), and the integral of the signal derived from proton (B) The value was taken as Int _B. From these values, the imidization rate (%) was determined by the following formula (NMR-1).

(Method for calculating imidization rate of polyamide-imide resin)
In the HSQC spectrum obtained by using a solution containing a polyimide resin as a measurement sample, the integral value of the signal derived from proton (C) in formula (10XXX) is Int _C , the signal derived from proton (D) and proton (E) Int _DE is the average value of the integrated values of . From these values, the β value was determined by the following formula (NMR-2).

Next, for a plurality of polyimide resins, the β value according to the formula (NMR-2) and the imidization rate (%) according to the formula (NMR-1) were obtained, and from these results the following correlation formula (NMR-3) was obtained. .

Then, in the HSQC spectrum obtained by using the solution containing the polyamide-imide resin as the measurement sample, the β value was determined by the formula (NMR-2) in the same manner as described above. By substituting this β value into the above correlation formula (NMR-3), the imidization rate (%) of the polyamide-imide resin was obtained.

<Measurement of total light transmittance (Tt)>
The total light transmittance Tt of the obtained polyamide-imide film was measured according to JIS K7105:1981 using a fully automatic direct-reading haze computer HGM-2DP manufactured by Suga Test Instruments Co., Ltd.

<Measurement of yellowness index (YI value)>
The yellowness index (Yellow Index: YI value) of the obtained polyamideimide film is measured using an ultraviolet-visible near-infrared spectrophotometer V-670 manufactured by JASCO Corporation in accordance with JIS K 7373:2006. did. After the background measurement was performed without the sample, the sample was set in the sample holder and the transmittance was measured with respect to light of 300 to 800 nm to obtain tristimulus values (X, Y, Z). The YI value was calculated based on the following formula.

<Measurement of surface hardness>
As the surface hardness of the obtained polyamideimide film, the pencil hardness of the sample surface was measured according to JIS K5600-5-4:1999. The measurement was carried out under the conditions of a load of 100 g and a scanning speed of 60 mm/min, and the presence or absence of scratches was evaluated under an illumination condition of a light quantity of 4,000 lux to determine the pencil hardness.

<Measurement of elastic modulus>
The elastic modulus of the resulting polyamide-imide film was measured using Autograph AG-IS manufactured by Shimadzu Corporation. A film cut into a width of 10 mm was used as a test piece, and an SS curve was measured under conditions of a distance between chucks of 500 mm and a tensile speed of 20 mm/min, and the elastic modulus was calculated from the slope.

<Measurement of bending resistance>
As the bending resistance of the obtained polyamide-imide film, the number of times of reciprocating bending was measured using an MIT folding fatigue tester (model 0530) manufactured by Toyo Seiki Seisakusho Co., Ltd. A film cut to a thickness of 50 μm and a width of 10 mm was used as a test piece, and the number of times of reciprocating bending until the film broke was measured under the conditions of R=1 mm, 135°, a load of 0.75 kgf, and a speed of 175 cpm.

[Example 1]
Under a nitrogen atmosphere, 52 g (162.38 mmol) of 2,2′-bis(trifluoromethyl)benzidine (TFMB) and N,N-dimethylacetamide adjusted to a water content of 500 ppm were placed in a 1 L separable flask equipped with a stirring blade. (DMAc) 693.8 g was added and TFMB was dissolved in DMAc with stirring at room temperature. Next, 28.90 g (65.05 mmol) of 4,4′-(hexafluoroisopropylidene)diphthalic dianhydride (6FDA) and 3,3′,4,4′-biphenyltetracarboxylic dianhydride were placed in a flask. (BPDA) 9.57 g (32.52 mmol) was added and stirred at room temperature for 3 hours. After that, 13.21 g (63.10 mmol) of terephthaloyl chloride (TPC) was added to the flask and stirred at room temperature for 1 hour. Next, 4.99 g (63.10 mmol) of pyridine and 21.91 g (214.66 mmol) of acetic anhydride were added to the flask and stirred at room temperature for 30 minutes. After stirring for hours, a reaction solution was obtained.
The resulting reaction solution was cooled to room temperature and thrown into a large amount of methanol in the form of a thread, and the deposited precipitate was taken out, immersed in methanol for 6 hours, and washed with methanol. Next, the precipitate was dried under reduced pressure at 100° C. to obtain a polyamide-imide resin.
DMAc was added to the resulting polyamide-imide resin to a concentration of 15% by mass to prepare a polyamide-imide varnish. The obtained polyamide-imide varnish was applied on a smooth surface of a polyester base material (manufactured by Toyobo Co., Ltd., trade name "A4100") using an applicator so that the film thickness of the self-supporting film was 55 μm, and was heated at 50 ° C.30. minutes, then 140° C. for 15 minutes to obtain a self-supporting film. The self-supporting film was fixed to a metal frame and dried in the atmosphere at 300° C. for 30 minutes to obtain a polyamide-imide film with a film thickness of 50 μm.

[Example 2]
In the same manner as in Example 1, except that the water content of DMAc in Example 1 was adjusted to 100 ppm, and the heating time after the temperature was raised to 70 ° C. was changed to 1 hour to obtain a polyamideimide resin. A polyamideimide film was obtained.

[Example 3]
Under a nitrogen atmosphere, 52 g (162.38 mmol) of 2,2′-bis(trifluoromethyl)benzidine (TFMB) and N,N-dimethylacetamide adjusted to a water content of 500 ppm were placed in a 1 L separable flask equipped with a stirring blade. (DMAc) 657.63 g was added and TFMB was dissolved in DMAc with stirring at room temperature. Next, 21.67 g (48.79 mmol) of 4,4′-(hexafluoroisopropylidene)diphthalic dianhydride (6FDA) and 3,3′,4,4′-biphenyltetracarboxylic dianhydride were placed in a flask. (BPDA) 4.78 g (16.26 mmol) was added and stirred at room temperature for 3 hours. After that, 19.81 g (97.57 mmol) of terephthaloyl chloride (TPC) was added to the flask and stirred at room temperature for 1 hour. Then, 7.49 g (94.65 mmol) of pyridine and 14.61 g (143.11 mmol) of acetic anhydride were added to the flask and stirred at room temperature for 30 minutes. After stirring for hours, a reaction solution was obtained.
The resulting reaction solution was cooled to room temperature and thrown into a large amount of methanol in the form of a thread, and the deposited precipitate was taken out, immersed in methanol for 6 hours, and washed with methanol. Next, the precipitate was dried under reduced pressure at 100° C. to obtain a polyamide-imide resin.
DMAc was added to the resulting polyamide-imide resin to a concentration of 15% by mass to prepare a polyamide-imide varnish. The obtained polyamide-imide varnish was applied on a smooth surface of a polyester base material (manufactured by Toyobo Co., Ltd., trade name "A4100") using an applicator so that the film thickness of the self-supporting film was 55 μm, and was heated at 50 ° C.30. minutes, then 140° C. for 15 minutes to obtain a self-supporting film. The self-supporting film was fixed to a metal frame and dried in the atmosphere at 300° C. for 30 minutes to obtain a polyamide-imide film with a film thickness of 50 μm.

[Example 4]
Under a nitrogen atmosphere, 52 g (162.38 mmol) of 2,2′-bis(trifluoromethyl)benzidine (TFMB) and N,N-dimethylacetamide adjusted to a water content of 500 ppm were placed in a 1 L separable flask equipped with a stirring blade. (DMAc) 673.93 g was added and TFMB was dissolved in DMAc with stirring at room temperature. Next, 28.90 g (65.05 mmol) of 4,4′-(hexafluoroisopropylidene)diphthalic dianhydride (6FDA) was added to the flask and stirred at room temperature for 3 hours. After that, 19.81 g (97.57 mmol) of terephthaloyl chloride (TPC) was added to the flask and stirred at room temperature for 1 hour. Then, 7.49 g (94.65 mmol) of pyridine and 14.61 g (143.11 mmol) of acetic anhydride were added to the flask and stirred at room temperature for 30 minutes. After stirring for hours, a reaction solution was obtained.
The resulting reaction solution was cooled to room temperature and thrown into a large amount of methanol in the form of a thread, and the deposited precipitate was taken out, immersed in methanol for 6 hours, and washed with methanol. Next, the precipitate was dried under reduced pressure at 100° C. to obtain a polyamide-imide resin.
DMAc was added to the resulting polyamide-imide resin to a concentration of 15% by mass to prepare a polyamide-imide varnish. The obtained polyamide-imide varnish was applied on a smooth surface of a polyester base material (manufactured by Toyobo Co., Ltd., trade name "A4100") using an applicator so that the film thickness of the self-supporting film was 55 μm, and was heated at 50 ° C.30. minutes, then 140° C. for 15 minutes to obtain a self-supporting film. The self-supporting film was fixed to a metal frame and dried in the atmosphere at 230° C. for 30 minutes to obtain a polyamide-imide film with a thickness of 50 μm.

[Example 5]
Under a nitrogen atmosphere, 52 g (162.38 mmol) of 2,2′-bis(trifluoromethyl)benzidine (TFMB) and N,N-dimethylacetamide adjusted to a water content of 500 ppm were placed in a 1 L separable flask equipped with a stirring blade. (DMAc) 734.10 g was added and TFMB was dissolved in DMAc with stirring at room temperature. Next, 28.90 g (65.05 mmol) of 4,4′-(hexafluoroisopropylidene)diphthalic dianhydride (6FDA) was added to the flask and stirred at room temperature for 3 hours. After that, 28.80 g (97.57 mmol) of 4,4′-oxybis(benzoyl chloride) (OBBC) was added to the flask and stirred at room temperature for 1 hour. Then, 7.49 g (94.65 mmol) of pyridine and 14.61 g (143.11 mmol) of acetic anhydride were added to the flask and stirred at room temperature for 30 minutes. After stirring for hours, a reaction solution was obtained.
The resulting reaction solution was cooled to room temperature and thrown into a large amount of methanol in the form of a thread, and the deposited precipitate was taken out, immersed in methanol for 6 hours, and washed with methanol. Next, the precipitate was dried under reduced pressure at 100° C. to obtain a polyamide-imide resin.
DMAc was added to the resulting polyamide-imide resin to a concentration of 15% by mass to prepare a polyamide-imide varnish. The obtained polyamide-imide varnish was applied on a smooth surface of a polyester base material (manufactured by Toyobo Co., Ltd., trade name "A4100") using an applicator so that the film thickness of the self-supporting film was 55 μm, and was heated at 50 ° C.30. minutes, then 140° C. for 15 minutes to obtain a self-supporting film. The self-supporting film was fixed to a metal frame and dried in the atmosphere at 300° C. for 30 minutes to obtain a polyamide-imide film with a film thickness of 50 μm.

[Example 6]
Under a nitrogen atmosphere, 52 g (162.38 mmol) of 2,2′-bis(trifluoromethyl)benzidine (TFMB) and N,N-dimethylacetamide adjusted to a water content of 500 ppm were placed in a 1 L separable flask equipped with a stirring blade. (DMAc) 734.10 g was added and TFMB was dissolved in DMAc with stirring at room temperature. Next, 28.90 g (65.05 mmol) of 4,4′-(hexafluoroisopropylidene)diphthalic dianhydride (6FDA) was added to the flask and stirred at room temperature for 3 hours. After that, 28.80 g (97.57 mmol) of 4,4′-oxybis(benzoyl chloride) (OBBC) was added to the flask and stirred at room temperature for 1 hour. Then, 7.49 g (94.65 mmol) of pyridine and 26.56 g (260.2 mmol) of acetic anhydride were added to the flask and stirred at room temperature for 30 minutes. After stirring for hours, a reaction solution was obtained.
The resulting reaction solution was cooled to room temperature and thrown into a large amount of methanol in the form of a thread, and the deposited precipitate was taken out, immersed in methanol for 6 hours, and washed with methanol. Next, the precipitate was dried under reduced pressure at 100° C. to obtain a polyamide-imide resin.
DMAc was added to the resulting polyamide-imide resin to a concentration of 15% by mass to prepare a polyamide-imide varnish. The obtained polyamide-imide varnish was applied on a smooth surface of a polyester base material (manufactured by Toyobo Co., Ltd., trade name "A4100") using an applicator so that the film thickness of the self-supporting film was 55 μm, and was heated at 50 ° C.30. minutes, then 140° C. for 15 minutes to obtain a self-supporting film. The self-supporting film was fixed to a metal frame and dried in the atmosphere at 300° C. for 30 minutes to obtain a polyamide-imide film with a film thickness of 50 μm.

[Example 7]
Under a nitrogen atmosphere, 52 g (162.38 mmol) of 2,2′-bis(trifluoromethyl)benzidine (TFMB) and N,N-dimethylacetamide adjusted to a water content of 500 ppm were placed in a 1 L separable flask equipped with a stirring blade. (DMAc) 667.75 g was added and TFMB was dissolved in DMAc with stirring at room temperature. Next, 21.67 g (48.79 mmol) of terephthaloyl chloride (TPC) 4,4′-(hexafluoroisopropylidene)diphthalic dianhydride (6FDA) was added to the flask and stirred at room temperature for 3 hours. After that, 9.60 g (32.52 mmol) of 4,4′-oxybis(benzoyl chloride) (OBBC) and 16.51 g (81.31 mmol) of terephthaloyl chloride (TPC) were added to the flask and stirred at room temperature for 1 hour. . Next, 8.73 g (110.42 mmol) of pyridine and 10.96 g (107.33 mmol) of acetic anhydride were added to the flask and stirred at room temperature for 30 minutes. After stirring for hours, a reaction solution was obtained.
The resulting reaction solution was cooled to room temperature and thrown into a large amount of methanol in the form of a thread, and the deposited precipitate was taken out, immersed in methanol for 6 hours, and washed with methanol. Next, the precipitate was dried under reduced pressure at 100° C. to obtain a polyamide-imide resin.
DMAc was added to the resulting polyamide-imide resin to a concentration of 15% by mass to prepare a polyamide-imide varnish. The obtained polyamide-imide varnish was applied on a smooth surface of a polyester base material (manufactured by Toyobo Co., Ltd., trade name "A4100") using an applicator so that the film thickness of the self-supporting film was 55 μm, and was heated at 50 ° C.30. minutes, then 140° C. for 15 minutes to obtain a self-supporting film. The self-supporting film was fixed to a metal frame and dried in the atmosphere at 300° C. for 30 minutes to obtain a polyamide-imide film with a film thickness of 50 μm.

[Comparative Example 1]
A polyamideimide film was obtained in the same manner as in Example 1 except that the stirring time after the temperature was raised to 70° C. was changed to 1 hour to obtain a polyamideimide resin.

[Comparative Example 2]
A polyamideimide film was obtained in the same manner as in Example 3 except that the stirring time after the temperature was raised to 70° C. in Example 3 was changed to 1 hour to obtain a polyamideimide resin.

[Comparative Example 3]
Under a nitrogen atmosphere, 52 g (162.38 mmol) of 2,2′-bis(trifluoromethyl)benzidine (TFMB) and N,N-dimethylacetamide adjusted to a water content of 500 ppm were placed in a 1 L separable flask equipped with a stirring blade. (DMAc) 831.46 g was added and TFMB was dissolved in DMAc with stirring at room temperature. Next, 72.24 g (162.62 mmol) of 4,4′-(hexafluoroisopropylidene)diphthalic dianhydride (6FDA) was added to the flask and stirred at room temperature for 3 hours. Next, 6.43 g (81.31 mmol) of pyridine and 36.52 g (357.77 mmol) of acetic anhydride were added to the flask and stirred at room temperature for 30 minutes. After stirring for hours, a reaction solution was obtained.
The resulting reaction solution was cooled to room temperature and thrown into a large amount of methanol in the form of a thread, and the deposited precipitate was taken out, immersed in methanol for 6 hours, and washed with methanol. Next, the precipitate was dried under reduced pressure at 100° C. to obtain a polyimide resin.
DMAc was added to the obtained polyimide resin so that the concentration was 15% by mass to prepare a polyimide varnish. The obtained polyimide varnish was applied on a smooth surface of a polyester base material (manufactured by Toyobo Co., Ltd., trade name "A4100") using an applicator so that the film thickness of the self-supporting film was 55 μm, and was applied at 50° C. for 30 minutes. Then, it was dried at 140° C. for 15 minutes to obtain a self-supporting film. The self-supporting film was fixed to a metal frame and dried in the atmosphere at 300° C. for 30 minutes to obtain a polyimide film having a thickness of 50 μm.

[Comparative Example 4]
Under a nitrogen atmosphere, 52 g (162.38 mmol) of 2,2′-bis(trifluoromethyl)benzidine (TFMB) and N,N-dimethylacetamide adjusted to a water content of 500 ppm were placed in a 1 L separable flask equipped with a stirring blade. (DMAc) 733.51 g was added and TFMB was dissolved in DMAc with stirring at room temperature. Next, 28.90 g (65.05 mmol) of 4,4′-(hexafluoroisopropylidene)diphthalic dianhydride (6FDA) and 3,3′,4,4′-biphenyltetracarboxylic dianhydride were placed in a flask. (BPDA) 28.71 g (97.57 mmol) was added and stirred at room temperature for 3 hours. Next, 6.43 g (81.31 mmol) of pyridine and 36.52 g (357.77 mmol) of acetic anhydride were added to the flask and stirred at room temperature for 30 minutes. After stirring for hours, a reaction solution was obtained.
The resulting reaction solution was cooled to room temperature and thrown into a large amount of methanol in the form of a thread, and the deposited precipitate was taken out, immersed in methanol for 6 hours, and washed with methanol. Next, the precipitate was dried under reduced pressure at 100° C. to obtain a polyimide resin.
DMAc was added to the obtained polyimide resin so that the concentration was 15% by mass to prepare a polyimide varnish. The obtained polyimide varnish was applied on a smooth surface of a polyester base material (manufactured by Toyobo Co., Ltd., trade name "A4100") using an applicator so that the film thickness of the self-supporting film was 55 μm, and was applied at 50° C. for 30 minutes. Then, it was dried at 140° C. for 15 minutes to obtain a self-supporting film. The self-supporting film was fixed to a metal frame and dried in the atmosphere at 300° C. for 30 minutes to obtain a polyimide film having a thickness of 50 μm.

[Comparative Example 5]
A polyamideimide film was obtained in the same manner as in Example 1, except that the moisture content of DMAc was changed to 1,000 ppm to obtain a polyamideimide resin.

[Comparative Example 6]
A polyamideimide film was prepared in the same manner as in Example 1 except that the moisture content of DMAc in Example 1 was changed to 1,700 ppm and the stirring time after heating to 70 ° C. was changed to 5 hours to obtain a polyamideimide resin. Obtained.

[Comparative Example 7]
A polyamideimide film was obtained in the same manner as in Example 5 except that the stirring time after the temperature was raised to 70° C. in Example 5 was changed to 30 minutes to obtain a polyamideimide resin.

[Comparative Example 8]
A polyamideimide film was obtained in the same manner as in Example 7, except that the stirring time after the temperature was raised to 70° C. was changed to 30 minutes to obtain a polyamideimide resin.

[Example 8]
In a nitrogen gas atmosphere, 45 g (140.5 mmol) of 2,2′-bis(trifluoromethyl)benzidine (TFMB) and N,N-dimethyl prepared to have a water content of 200 ppm were placed in a 1 L separable flask equipped with a stirring blade. 600.9 g of acetamide (DMAc) was added and TFMB was dissolved in DMAc with stirring at room temperature. Next, 4.14 g (14.1 mmol) of 3,3′,4,4′-biphenyltetracarboxylic dianhydride (BPDA) was added to the flask and stirred at room temperature for 2.5 hours. 25.01 g (56.3 mmol) of -(hexafluoroisopropylidene)diphthalic dianhydride (6FDA) was added and stirred at room temperature for 15 hours. Further, 4.15 g (14.1 mmol) of 4,4′-oxybis(benzoyl chloride) (OBBC) and 11.43 g (56.3 mmol) of terephthaloyl chloride (TPC) were added to the flask and stirred at room temperature for 1 hour. . Next, 21.55 g (211.1 mmol) of acetic anhydride and 3.28 g (35.2 mmol) of 4-picoline were added to the flask, stirred at room temperature for 30 minutes, heated to 70° C. using an oil bath, and further After stirring for 3 hours, a reaction solution was obtained.
After cooling the resulting reaction solution to room temperature, 647 g of methanol and 180 g of ion-exchanged water were added to obtain a polyamideimide precipitate. It was soaked in methanol for 12 hours, collected by filtration and washed with methanol. Next, the precipitate was dried under reduced pressure at 100° C. to obtain a polyamide-imide resin. Table 1 shows the molar ratio of each component.
DMAc was added to the resulting polyamide-imide resin to a concentration of 15% by mass to prepare a polyamide-imide varnish. The obtained polyamide-imide varnish was applied on a smooth surface of a polyester base material (manufactured by Toyobo Co., Ltd., trade name "A4100") using an applicator so that the film thickness of the self-supporting film was 55 μm, and was heated at 50 ° C. and 30 ° C. minutes and then at 140° C. for 15 minutes to obtain a self-supporting film. The self-supporting film was fixed to a metal frame and dried in the atmosphere at 300° C. for 30 minutes to obtain a polyamide-imide film having a thickness of 50 μm.

[Example 9]
In a nitrogen gas atmosphere, 14.67 g (45.8 mmol) of 2,2′-bis(trifluoromethyl)benzidine (TFMB) and N,N prepared to have a water content of 200 ppm were placed in a 1 L separable flask equipped with a stirring blade. -Dimethylacetamide (DMAc) 233.3 g was added and TFMB was dissolved in DMAc with stirring at room temperature. Next, 4.283 g (13.8 mmol) of 4,4'-oxydiphthalic dianhydride (OPDA) was added to the flask and stirred at room temperature for 16.5 hours. After that, 1.359 g (4.61 mmol) of 4,4′-oxybis(benzoyl chloride) (OBBC) and 5.609 g (27.6 mmol) of terephthaloyl chloride (TPC) were added to the flask and stirred at room temperature for 1 hour. . Next, 4.937 g (48.35 mmol) of acetic anhydride and 1.501 g (16.12 mmol) of 4-picoline were added to the flask, stirred at room temperature for 30 minutes, heated to 70°C using an oil bath, and further After stirring for 3 hours, a reaction solution was obtained.
After cooling the resulting reaction solution to room temperature, 360 g of methanol and 170 g of ion-exchanged water were added to obtain a polyamideimide precipitate. It was soaked in methanol for 12 hours, collected by filtration and washed with methanol. Next, the precipitate was dried under reduced pressure at 100° C. to obtain a polyamide-imide resin. Table 1 shows the molar ratio of each component.
A polyamideimide film having a thickness of 50 μm was obtained from the polyamideimide resin obtained in Example 9 in the same manner as in Example 8.

[Example 10]
4,4'-Oxydiphthalic dianhydride (OPDA) 4.283 g was changed to 4,4'-(hexafluoroisopropylidene) diphthalic dianhydride (6FDA) 6.140 g, 2,2'-bis( except that 8.809 g (27.5 mmol) of TFMB and 3.889 g (18.3 mmol) of 2,2′-dimethylbenzidine (MB) were used instead of 14.67 g (45.8 mmol) of trifluoromethyl)benzidine (TFMB). obtained a polyamideimide resin in the same manner as in Example 9. Table 1 shows the molar ratio of each component.
A polyamideimide film having a thickness of 50 μm was obtained from the polyamideimide resin obtained in Example 10 in the same manner as in Example 8.

[Example 11]
Polyamideimide in the same manner as in Example 9, except that 3.670 g (18.3 mmol) of 4,4'-diaminodiphenyl ether (ODA) was used instead of 3.889 g of 2,2'-dimethylbenzidine (MB). A resin was obtained. Table 1 shows the molar ratio of each component.
A polyamideimide film having a thickness of 50 μm was obtained from the polyamideimide resin obtained in Example 11 in the same manner as in Example 8.

Table 1 below shows the ratio of each structural unit in the polyamideimide resin (B) contained in the polyamideimide varnish obtained in the above example and the resin (B) contained in the varnish obtained in the comparative example and the synthesis conditions. Table 1 also shows the results of measuring the imidization rate of the polyamide-imide resin (B) and the resin (B) according to the above measuring method. In Table 1, the imidization rate of the polyamideimide resin (B) and the resin (B) is "imidization rate B", the water content in the solvent at the time of starting the step (1) is "w [ppm]", The heating time in step (2) is "t [minute]", and the ratio of the molar amount of the dehydrating agent added in step (2) to the molar amount of tetracarboxylic dianhydride added in step (1) is " Amount of dehydrating agent added”. Polyimide resin B was prepared in the same manner as polyamide-imide resin B, except that the resin used in the measurement of imidization ratio B of polyimide resin B obtained in Comparative Examples 3 and 4 was changed.

The results of measuring the imidization rate of the polyamideimide resin (A) contained in the polyamideimide film obtained in the above example and the resin (A) contained in the film obtained in the above comparative example according to the above measurement method are shown in Table. 2 as "imidization rate A". Here, in the measurement of the imidization rate of polyimide resin A contained in the polyimide films obtained in Comparative Examples 3 and 4, polyimide resin A was prepared in the same manner as polyamideimide resin A except that the resin was changed. Further, the films obtained in Examples and Comparative Examples were measured for pencil hardness, yellowness index (YI), total light transmittance (Tt), elastic modulus and bending resistance (number of times of reciprocating bending) according to the above measuring methods. Table 1 shows the results obtained. In addition, the ratio of the ratio of each structural unit in the polyamideimide resin (A) contained in the polyamideimide film and the resin (A) contained in the film obtained in the above comparative example corresponds to the polyamideimide shown in Table 1. It is the same as the resin (B) and the ratio of the structural units in the resin (B). Moreover, in Examples 10 and 11, it was confirmed that signals derived from structures other than the repeating unit having an amic acid and the repeating unit having an imide bond overlapped. Therefore, in the signal, the intensity of the non-overlapping portion was integrated, the original signal intensity was obtained from the area ratio of the portion, and the imidization ratios A and B were calculated.

Claims (13)

An imide having at least a structural unit derived from a diamine, a structural unit derived from a dicarboxylic acid, and a structural unit derived from a tetracarboxylic dianhydride, containing a fluorine atom, and having a proportion of 95% or more as measured by two-dimensional NMR. A film containing a polyamideimide resin A having a conversion rate ,
It has a structural unit derived from a diamine, a structural unit derived from a dicarboxylic acid, and a structural unit derived from a tetracarboxylic dianhydride, contains a fluorine atom, and is imidized by 60% or more as measured by two-dimensional NMR. and a resin composition containing at least a solvent . The diamine has the formula (3):

[In formula (3), X is formula (3e′):

[In formula (3e′), R ¹⁰ to R ¹⁷ each independently represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 12 carbon atoms, and are included in R ¹⁰ to R ¹⁷ Each hydrogen atom may be independently substituted with a halogen atom, and * represents a bond]
represents]
2. The film of claim 1, comprising at least one compound represented by: The dicarboxylic acid has the formula (2):

[In formula (2), Z is formula (2a) or formula (2b)

[In the formulas (2a) and (2b), U ¹ is a single bond, -O-, -CH ₂ -, -CH ₂ -CH ₂ -, -CH(CH ₃ )-, -C(CH ₃ ) _2- , -C(CF ₃ ) ₂ -, -Ar-, -SO ₂ -, -CO-, -O-Ar-O-, -Ar-O-Ar-, -Ar-CH ₂ -Ar-, -Ar-C(CH ₃ ) ₂ -Ar- or -Ar-SO ₂ -Ar-, Ar represents an arylene group having 6 to 20 carbon atoms, hydrogen atoms of which may be substituted with fluorine atoms, * represents a bond]
and B ¹ and B ² each independently represent OH or a halogen atom]
3. A film according to claim 1 or 2, comprising at least one compound represented by The tetracarboxylic dianhydride has the formula (4):

[In the formula (4), Y is the formula (4g):

[In formula (4g), W ¹ represents a single bond, -C(CH ₃ ) ₂ - or -C(CF ₃ ) ₂ -, and * represents a bond]
represents]
The film according to any one of claims 1 to 3, comprising at least one compound represented by The film of any one of claims 1-4 , having a YI of 3 or less. 6. The film of any of claims 1-5 , having a pencil hardness of 3B or greater measured according to ASTM D 3363 under 4,000 lux illumination conditions. It has a structural unit derived from a diamine, a structural unit derived from a dicarboxylic acid, and a structural unit derived from a tetracarboxylic dianhydride , contains a fluorine atom, and is imidized by 60% or more as measured by two-dimensional NMR. and a resin composition containing at least a solvent. The diamine has the formula (3):

[In formula (3), X is formula (3e′):

[In formula (3e′), R ¹⁰ to R ¹⁷ each independently represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 12 carbon atoms, and are included in R ¹⁰ to R ¹⁷ Each hydrogen atom may be independently substituted with a halogen atom, and * represents a bond]
represents]
The resin composition according to claim 7 , comprising at least one compound represented by. The dicarboxylic acid has the formula (2):

[In formula (2), Z is formula (2a) or formula (2b):

[In the formulas (2a) and (2b), U ¹ is a single bond, -O-, -CH ₂ -, -CH ₂ -CH ₂ -, -CH(CH ₃ )-, -C(CH ₃ ) _2- , -C(CF ₃ ) ₂ -, -Ar-, -SO ₂ -, -CO-, -O-Ar-O-, -Ar-O-Ar-, -Ar-CH ₂ -Ar-, -Ar-C(CH ₃ ) ₂ -Ar- or -Ar-SO ₂ -Ar-, Ar represents an arylene group having 6 to 20 carbon atoms, hydrogen atoms of which may be substituted with fluorine atoms, * represents a bond]
and B ¹ and B ² each independently represent OH or a halogen atom]
The resin composition according to claim 7 or 8 , comprising at least one compound represented by. The tetracarboxylic dianhydride has the formula (4):

[In the formula (4), Y is the formula (4g):

[In formula (4g), W ¹ represents a single bond, -C(CH ₃ ) ₂ - or -C(CF ₃ ) ₂ -, and * represents a bond]
represents]
The resin composition according to any one of claims 7 to 9 , comprising at least one compound represented by A film obtained by drying a coating film of the resin composition according to any one of claims 7 to 10 . A method for producing a film, comprising at least a step of drying a coating film of the resin composition according to any one of claims 7 to 10. 7. The film according to any one of claims 1 to 6, which is a film for a front panel of an image display device.