JP6675509B2 - Film, resin composition and method for producing polyamideimide resin - Google Patents

Description

  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.

  At present, 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 the expansion of such uses, an image display device (flexible display) having flexible characteristics is required. The image display device includes a display element such as a liquid crystal display element or an organic EL display element, and components such as a polarizing plate, a retardation plate, and a front plate. In order to achieve a flexible display, all these components need to have flexibility.

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

  Therefore, utilization of a polymer material as a substitute for glass is being studied. Since the front plate made of a polymer material easily exhibits flexible characteristics, it can be expected to be used for various applications. There are various kinds of resins having flexibility, and one of them is a polyamideimide resin. Polyamideimide resins are used in various applications from the viewpoints of transparency and heat resistance, and various methods for producing the same have been studied.

For example, Patent Document 1 discloses a unit structure derived from TFDB (2,2′-bistrifluoromethyl-4,4′-biphenyldiamine) and 6FDA (4,4 ′-(hexafluoroisopropylidene) diphthalic dianhydride. A copolymerized polyamide-imide film is described, which contains a resin in which a unit structure derived from a TPC (tetrephthaloyl chloride; 1,4-benzenedicarbonyl chloride) is copolymerized.
Patent Document 2 discloses a copolymerized polyamide film having excellent mechanical properties such as pencil hardness.

JP-T-2015-521686 JP 2014-528490A

  Conventionally, in a film containing a polyamideimide resin used as a front plate, it is required to exhibit high transparency and high surface hardness of the film, but the evaluation result of the surface hardness depends on a film manufacturing method and film measurement conditions. However, there were problems such as a big difference.

  For example, the film described in Patent Document 1 has an average transmittance of at least 89% at a wavelength of 380 to 780 nm, but it is not clear whether the film has a sufficiently high surface hardness. Further, there is no suggestion about a form suitable for developing high surface hardness. Patent Document 2 describes that the film has a surface pencil hardness of 3H or more, but when the pencil hardness is evaluated, the result may differ depending on the illuminance condition used.

  Therefore, an object of the present invention is to provide a film having a high surface hardness, including a polyamideimide resin having a high imidization ratio, which is suitably used particularly as a front plate of a flexible display or the like.

  Means for Solving the Problems In order to solve the above-mentioned problems, the present inventors have conducted intensive studies on various characteristics of polyamide-imide resin, focusing on the imidization ratio of polyamide-imide resin and the surface hardness of the obtained film. As a result, they have found that the use of a polyamideimide resin satisfying specific requirements can increase the surface hardness of the film, 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 embodiments.
[1] An imidization ratio of at least 95% as measured by two-dimensional NMR, having at least a constituent unit derived from a diamine, a constituent unit derived from a dicarboxylic acid, and a constituent unit derived from a tetracarboxylic dianhydride. A film comprising a polyamide-imide resin A having the formula:
[2] The diamine is represented by the formula (3):

[In the formula (3), X is the 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 the above [1], comprising at least one compound represented by the following formula:
[3] The dicarboxylic acid has the formula (2):

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

Wherein (2a) and formula (2b), ^{U 1} represents 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—, and * represents a bond.
Wherein B ¹ and B ² each independently represent OH or a halogen atom]
The film according to the above [1] or [2], comprising at least one compound represented by the following formula:
[4] The tetracarboxylic dianhydride is represented by the formula (4):

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

[In the 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 the above [1] to [3], comprising at least one compound represented by the following formula:
[5] The film according to any of [1] to [4], wherein the polyamideimide resin A contains a fluorine atom.
[6] The film according to any of [1] to [5], having a YI of 3 or less.
[7] The film according to any one of [1] to [6], which has a pencil hardness of 3B or more as measured under illuminance conditions of 4,000 lux according to ASTM D3363.
[8] It has a constituent unit derived from a diamine, a constituent unit derived from a dicarboxylic acid, and a constituent unit derived from a tetracarboxylic dianhydride, and has an imidation ratio of 60% or more as measured by two-dimensional NMR. A resin composition comprising at least a polyamide-imide resin B having a solvent and a solvent.
[9] The diamine is represented by the formula (3):

[In the formula (3), X is the 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 the above [8], comprising at least one compound represented by the following formula:
[10] The dicarboxylic acid has the formula (2):

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

Wherein (2a) and formula (2b), ^{U 1} represents 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—, and * represents a bond.
Wherein B ¹ and B ² each independently represent OH or a halogen atom]
The resin composition according to the above [8] or [9], comprising at least one compound represented by the following formula:
[11] The tetracarboxylic dianhydride has the formula (4):

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

[In the 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 the above [8] to [10], comprising at least one compound represented by the following formula:
[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 polyamide-imide resin, comprising at least a step of adding a dehydrating agent and a tertiary amine to a solution containing at least a polyamide-imide resin precursor and heating at a temperature of 70 to 120 ° C. Assuming that the amount of water in the solvent at the start of (1) is w (ppm) and the heating time in step (2) is t (minutes), w and t are represented by the following formulas:

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

  ADVANTAGE OF THE INVENTION According to this invention, the film which has a high surface hardness containing the polyamideimide resin which has a high imidation ratio, and is preferably used as a front plate etc. in an image display apparatus etc. is obtained.

  Hereinafter, embodiments of the present invention will be described in detail. Note that the scope of the present invention is not limited to the embodiment described here, and various changes can be made without departing from the spirit of the present invention.

  The film of the present invention contains a polyamideimide resin A having an imidization ratio of 95% or more as measured by two-dimensional NMR. When the imidization ratio of the polyamide-imide resin A is lower than 95%, the polyamide-imide having an excessively flexible primary structure tends to be formed, so that the surface hardness of the film containing the polyamide-imide resin cannot be sufficiently increased. From the viewpoint of the stability of the polyamideimide varnish, the imidization ratio of the polyamideimide resin A is preferably 97% or more, more preferably 98% or more, and still more preferably 99% or more. The higher the imidization ratio, the better. The upper limit is not particularly limited, and may be 100% or less. Examples of the method for adjusting the imidation ratio of the polyamide-imide resin A to the above range include a method of producing a film using a polyamide resin composition described below, and then performing imidation, and a method of producing the film by a production method described below. And a method of producing a film using the composition containing the polyamideimide resin.

  The imidation ratio of the polyamide-imide resin A is a ratio of the number of moles of the imide bond in the polyamide-imide resin A to twice the value of the number of moles of the structural unit derived from the tetracarboxylic dianhydride in the polyamide-imide resin A. Which is measured by two-dimensional NMR in this specification. Conventionally, the measurement of the imidation ratio of a polyamide-imide resin has often been performed using an infrared spectrum. However, in this method, as described in JP-A-2004-338160, a resin containing imide is heated. However, it is necessary to measure a sufficiently imidized resin. However, it is necessary to heat at a high temperature in order to sufficiently imidize, and there is an error because a decomposition reaction of the resin may occur at the same time in the heating process, so that the imidation ratio can be accurately measured. Did not. The present inventors studied measuring the imidation ratio of the polyamide-imide resin with high accuracy using two-dimensional NMR, and as a result, a polyamide having a predetermined imidation ratio measured using two-dimensional NMR It has been found that a film containing imide resin A achieves high surface hardness. The imidation ratio of the polyamide imide resin A can be measured using two-dimensional NMR, using a predetermined solution obtained by dissolving the film in deuterated dimethyl sulfoxide (DMSO-d6) as a measurement sample. The details of the measurement conditions of the two-dimensional NMR are as shown in Examples.

  The pencil hardness (surface hardness) of the film of the present invention is preferably 3 B or more, more preferably 2 B or more, still more preferably B or more, and particularly preferably HB, measured according to ASTM D 3363 under an illumination condition of 4,000 lux. Above, very preferably H or more, most preferably 2H or more. When the pencil hardness of the film of the present invention is equal to or more than the above lower limit, it is easy to prevent the surface of the image display device from being damaged when used as a front plate (window film) of the image display device, and the film shrinks and expands. Is preferable because it is easy to prevent the The upper limit of the pencil hardness of the film of the present invention is not particularly limited. The pencil hardness is measured according to JIS K5600-5-4: 1999. Specifically, the measurement is performed at a load of 100 g and a scanning speed of 60 mm / min, and the evaluation is performed under an illuminance condition of a light amount of 4,000 lux. When the pencil hardness is evaluated, the result may vary depending on the illuminance condition used. Specifically, compared to the pencil hardness measured and evaluated under illuminance conditions of 4,000 lux, the pencil hardness measured and evaluated under illuminance conditions of lower light intensity is lower than that of lower light intensity. As a result, scratches on the film become less visible, so that there is a high possibility that a higher pencil hardness than actual is obtained. Therefore, the pencil hardness in the present specification is a value obtained by evaluation under an illuminance condition of a light amount of 4,000 lux.

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

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 further 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, and particularly preferably 90, as measured according to JIS K 7105: 1981. % Or more. When the total light transmittance is equal to or more than the above lower limit, visibility when the film of the present invention is incorporated in an image display device is easily increased. 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 according to 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 having a thickness of 50 to 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 it is preferable that the thickness be 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, still more preferably 5.2 GPa or less, particularly preferably 5.0 GPa or less, most preferably, from the viewpoint of the flexibility of the film. Is 4.5 GPa or less. When the elastic modulus is equal to or less than the above upper limit, when the flexible display is bent, it is easy to suppress damage to other members due to the film. The lower limit of the elastic modulus of the film of the present invention is not particularly limited, but is usually 2.0 GPa or more. The modulus of elasticity can be determined by, for example, measuring the SS curve of a 10-mm wide test piece under the conditions of a chuck-to-chuck distance of 500 mm and a pulling speed of 20 mm / min using an Autograph AG-IS manufactured by Shimadzu Corporation, and determining the slope. Can be measured.

  The number of times of reciprocating bending of the film of the present invention is measured from the viewpoint of the bending resistance of the film under conditions of R = 1 mm, 135 °, a load of 0.75 kgf, and a speed of 175 cpm until the film breaks, and is preferably 10,000 times. The number is preferably 20,000 or more, more preferably 30,000 or more, particularly preferably 40,000 or more, and most preferably 50,000 or more. When the number of reciprocating bendings of the film of the present invention is equal to or more than the above lower limit, it is easy to suppress weaving wrinkles that may occur when the film is bent. The upper limit of the number of times of reciprocating bending of the film of the present invention is not particularly limited, but it is usually sufficiently practical if the film can be bent about 1,000,000 times or less. The number of times of reciprocating bending can be determined as a measurement sample using a MIT folding fatigue tester (Model 0530) manufactured by Toyo Seiki Seisaku-sho, Ltd., as a measurement sample cut out from a film having a thickness of 50 μm and a width of 10 mm.

  The polyamideimide resin A contained in the film of the present invention has 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.

［式（３）中、Ｘは２価の有機基を表す。］ The polyamide imide resin A contained in the film of the present invention has a structural unit derived from a diamine. Examples of the diamine include a compound represented by the formula (3). The polyamide imide resin A may have a structural unit derived from one kind of diamine, or may have a structural unit derived from two or more kinds of diamine.

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

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

X in the formula (3) represents a divalent organic group, and preferably represents 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. Examples of the divalent organic group include groups represented by formulas (3a) to (3i); hydrogen atoms in the groups represented by formulas (3a) to (3i) are methyl, fluoro, 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 (3a) to (3i),
* Represents a bond,
V ¹ ~V ³ are each independently a single _{bond, -O -, - S -,} - CH 2 -, - CH 2 -CH 2 -, - CH (CH 3) -, - C (CH 3) _{2 -, - C (CF 3} ) 2 -, - representing the or -CO- - SO _2. ]
One example is a single bond ^{V 1} and ^{V 3,} -O- or -S-, and, ^{V 2} is _{-CH 2 -, - C (CH} 3) 2 -, - C (CF 3) 2 — Or —SO ₂ —. The bonding position of V ¹ and V ² to each ring and the bonding position of V ² and V ³ to each ring are preferably at the meta or para position with respect to each ring. More preferably, there is.

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

  Specific examples of the diamine represented by the formula (3) include an aliphatic diamine, an aromatic diamine, and a mixture thereof. In the present embodiment, “aromatic diamine” refers to a diamine in which an amino group is directly bonded to an aromatic ring, and a part of the structure may include an aliphatic group or another substituent. This aromatic ring may be a single ring or a condensed ring, and examples thereof include a benzene ring, a naphthalene ring, an anthracene ring, and a fluorene ring, but are not limited thereto. Among these, a benzene ring is preferred. The “aliphatic diamine” refers to a diamine in which an amino group is directly bonded to an aliphatic group, and may have an aromatic ring or another substituent in a part of its structure.

  Examples of the aliphatic diamine include acyclic aliphatic diamines such as hexamethylene diamine, and 1,3-bis (aminomethyl) cyclohexane, 1,4-bis (aminomethyl) cyclohexane, norbornanediamine, and 4,4 ′. And cycloaliphatic diamines such as diaminodicyclohexylmethane. These can be used alone or in combination of two or more.

  Examples of the aromatic diamine include p-phenylenediamine, m-phenylenediamine, 2,4-toluenediamine, m-xylylenediamine, p-xylylenediamine, 1,5-diaminonaphthalene, and 2,6-diamino Aromatic diamine 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′-diaminodiphenylsulfone, 3,4′-diaminodiphenylsulfone, 3,3′-diaminodiphenylsulfone, 1,4-bis (4-aminophenoxy) benzene, 1, 3-bis (4-aminophenoxy) benzene, 4,4 ' Diaminodiphenyl sulfone, 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-methylphenyl) fluorene, 9,9-bis (4-amino-3 -Chlorophenyl) fluorene and 9,9-bis (4-amino-3-fluorophenyl) fluorene and the like having two or more aromatic rings. Family diamine. These can be used alone or in combination of two or more.

  As the aromatic diamine, preferably 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylpropane, 4,4'-diaminodiphenylether, 3,3'-diaminodiphenylether, 4,4'-diaminodiphenylsulfone, 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'-diaminodiphenylether, 4,4'-diaminodiphenylsulfone, 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 (tri Fluoromethyl) benzidine and 4,4′-bis (4-aminophenoxy) biphenyl. These can be used alone or in combination of two or more.

  Among the above-mentioned diamine compounds, from the viewpoint of the surface hardness, flexibility, bending resistance, transparency and yellowness of the film of the present invention, at least one selected from the group consisting of aromatic diamines having a biphenyl structure may be used. Preferably, it is 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 kinds, 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 that the polyamideimide resin A can easily increase the surface hardness and transparency of the film of the present invention, X in the formula (3) may have at least a structural unit derived from a diamine represented by the formula (3e ′). 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 the 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 preferably a hydrogen atom or 1 to carbon atoms. 6 represents an 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. Is also good. From the viewpoint of the 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. And particularly preferably a hydrogen atom or a trifluoromethyl group.

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

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

  When the polyamideimide resin A has a structural unit derived from two or more diamines, X in the formula (3) is a structural unit derived from a diamine represented by the formula (3e ′), preferably the formula (3e ″). Is preferably at least 30 mol%, more preferably at least 30 mol%, based on the entire structural units derived from the diamine contained in the polyamideimide resin A, from the viewpoint of improving the transparency and the ease of production of the film of the present invention. Is 50 mol% or more, more preferably 70 mol% or more.In the formula (3), X is the amount of the structural unit derived from the diamine represented by the formula (3e ′), preferably the formula (3e ″). The upper limit is not particularly limited, and may be 100 mol% or less based on the entire structural units derived from the diamine contained in the polyamideimide resin A. The ratio of structural units derived from a diamine where X in the formula (3) is represented by the formula (3e ′) or (3e ″) can be measured using, for example, two-dimensional NMR, or the charge 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。］ The polyamide imide resin A contained in the film of the present invention has a structural unit 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. Than the solubility in a solvent. The structural unit derived from dicarboxylic acid is preferably a structural unit derived from dicarboxylic acid dichloride. Examples of the dicarboxylic acid include a compound represented by the formula (2). The polyamide imide resin A may have a structural unit derived from one kind of dicarboxylic acid, or may have a structural unit derived from two or more kinds of dicarboxylic acids.

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

Z in the formula (2) represents a divalent organic group, and preferably represents 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. Examples of the divalent organic group include groups represented by the formulas (2a) and (2b); hydrogen atoms in the groups represented by the formulas (2a) and (2b) are methyl, fluoro, 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 (2a) and (2b),
* Represents a bond,
U ¹ represents 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 preferably a single bond, -O-, or represents a -Ar-O-Ar-. Ar represents an arylene group having 6 to 20 carbon atoms in which a hydrogen atom may be substituted by a fluorine atom, and specific examples include a phenylene group. ]

Specific examples of the dicarboxylic acid represented by the formula (2) include aromatic dicarboxylic acids, aliphatic dicarboxylic acids and their related acid chloride compounds, acid anhydrides, and the like. May be. Specific examples include dicarboxylic acid compounds of terephthalic acid; isophthalic acid; naphthalenedicarboxylic acid; 4,4′-biphenyldicarboxylic acid; 3,3′-biphenyldicarboxylic acid; a chain hydrocarbon having 8 or less carbon atoms; One of benzoic acid is a single _{bond, -CH 2 -, - C (} CH 3) 2 -, - C (CF 3) 2 -, - SO 2 -, - O -, - S -, - NR 9 -, - C (= O)-or a compound linked by a phenylene group; and their acid chloride compounds. 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 the formula (2) preferably contains at least one selected from terephthalic acid, 4,4′-biphenyldicarboxylic acid, 4,4′-oxybisbenzoic acid, and an acid chloride compound thereof. And more preferably 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, it is more preferable to include 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 polyamideimide resin A preferably has at least Z in the formula (2) having a structural unit represented by the formula (1).

[In the 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 hydrogen contained in R ^{1 to} R ⁸ The atoms may be each independently substituted with a halogen atom,
A is independently, -O -, - S -, - CO- or -NR ⁹ - represents, ^{R 9} represents a hydrocarbon group having 1 to 12 carbon atoms which may be substituted with a halogen atom,
m is an integer of 1 to 4,
* Represents a bond. ]

The symbols in the equation (1) will be described below.
A is independently, -O -, - S -, - CO- or -NR ⁹ - represents, wherein, ^{R 9} is a hydrocarbon group having 1 to 12 carbon atoms which may be substituted with a halogen atom Represents From the viewpoint of the flexibility of the film of the present invention, A preferably independently represents -O- or -S-, and more preferably represents -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 viewpoints of flexibility and surface hardness of the film of the present invention, R ^{1 to} R ⁸ each independently preferably represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, more preferably a hydrogen atom or a carbon atom. Represents an alkyl group of 1 to 3, more preferably a hydrogen atom. Here, the hydrogen atoms contained in R ^{1 to} R ⁸ may be each independently substituted with a halogen atom.
m is an integer in the range of 1 to 4, and is preferably an integer in the range of 1 to 3, more preferably 1 or 2, and still more preferably 1, from the viewpoint of availability of raw materials. When m is within the above range, the availability of raw materials is good, and the flexibility of the film of the present invention is easily increased.

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

  In a preferred embodiment in which the polyamideimide resin A contained in the film of the present invention has a structural unit represented by the formula (1) or (1 ′), the amount of the structural unit is included in the polyamideimide resin A. Based on all structural units, it is preferably at least 3 mol%, more preferably at least 5 mol%, further preferably at least 10 mol%, particularly preferably at least 20 mol%. When the amount of the structural unit represented by the formula (1) or the formula (1 ') is equal to or more than the above lower limit, the resin film tends to exhibit high flexibility, and thus the bending resistance is easily improved. The amount of the structural unit represented by the formula (1) or (1 ′) is preferably 45 mol% or less, more preferably 40 mol% or less, based on all the structural units contained in the polyamideimide resin A. , More preferably 30 mol% or less. When the amount of the structural unit represented by the formula (1) or the 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, a structural unit in which Z in the formula (2) is derived from a dicarboxylic acid represented by the formula (1) It is preferable to have at least. When the polyamide-imide resin has a structural unit derived from two or more dicarboxylic acids, and Z in the formula (2) has a structural unit derived from the dicarboxylic acid represented by the formula (1), the formula (1) The amount of the structural unit derived from the dicarboxylic acid represented by the formula (1) is preferably based on the entire structural unit derived from the dicarboxylic acid contained in the polyamideimide resin A, from the viewpoint of the surface hardness, elastic modulus, and flexibility of the film. Is at least 5 mol%, more preferably at least 7 mol%, further preferably at least 9 mol%, particularly preferably at least 11 mol%. The upper limit of the amount of the structural unit derived from the dicarboxylic acid represented by the formula (1) is not particularly limited as Z in the formula (2), and is based on the entire structural unit derived from the dicarboxylic acid contained in the polyamideimide resin A. 100 mol% or less. The ratio of the structural unit derived from the dicarboxylic acid in which Z in the formula (2) is represented by the formula (1) can be measured using, for example, two-dimensional NMR, or can be calculated from the charging ratio of the raw materials. it can.

［式（４）中、Ｙは、４価の有機基を表す。］ The polyamide imide resin A contained in the film of the present invention has a structural unit derived from tetracarboxylic dianhydride. Examples of the tetracarboxylic dianhydride include a compound represented by the formula (4). The polyamide imide resin A may have a structural unit derived from one kind of tetracarboxylic dianhydride, or may have a structural unit derived from two or more kinds of tetracarboxylic dianhydride. Good.

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

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

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

[In equations (4a) to (4j),
* Represents a bond,
W ¹ represents 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 an _-Ar-SO 2 -Ar-. Ar represents an arylene group having 6 to 20 carbon atoms in which a hydrogen atom may be substituted by a fluorine atom, and specific examples include a phenylene group. ]

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

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

  Specific examples of the aromatic tetracarboxylic dianhydride include non-condensed polycyclic aromatic tetracarboxylic dianhydrides, monocyclic aromatic tetracarboxylic dianhydrides and condensed polycyclic aromatic tetracarboxylic acids. Carboxylic dianhydrides are mentioned. Non-fused polycyclic aromatic tetracarboxylic dianhydrides include 4,4′-oxydiphthalic dianhydride (OPDA), 3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride, , 2 ', 3,3'-benzophenonetetracarboxylic dianhydride, 3,3', 4,4'-biphenyltetracarboxylic dianhydride (BPDA), 2,2 ', 3,3'-biphenyltetra Carboxylic dianhydride, 3,3 ′, 4,4′-diphenylsulfonetetracarboxylic 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-di (Carboxyphenyl) ethane dianhydride, 1,1-bis (3,4-dicarboxyphenyl) ethane dianhydride, bis (3,4-dicarboxyphenyl) methane dianhydride, bis (2,3-dicarboxy) Phenyl) methane dianhydride, 4,4 ′-(p-phenylenedioxy) diphthalic dianhydride, and 4,4 ′-(m-phenylenedioxy) diphthalic dianhydride. In addition, examples of the monocyclic aromatic tetracarboxylic dianhydride include 1,2,4,5-benzenetetracarboxylic dianhydride. Examples of the condensed polycyclic aromatic tetracarboxylic dianhydride include 2,3,6,7-naphthalenetetracarboxylic dianhydride. These can be used alone or in combination of two or more.

  Of these, 4,4'-oxydiphthalic dianhydride, 3,3 ', 4,4'-benzophenonetetracarboxylic dianhydride, and 2,2', 3,3'-benzophenonetetracarboxylic dianhydride are preferred. 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) Nyl) 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. These can be used alone or in combination of two or more.

  Examples of the aliphatic tetracarboxylic dianhydride include cyclic and acyclic aliphatic tetracarboxylic dianhydrides. The cycloaliphatic tetracarboxylic dianhydride is a tetracarboxylic dianhydride having an alicyclic hydrocarbon structure, and specific examples thereof include 1,2,4,5-cyclohexanetetracarboxylic dianhydride. , Cycloalkanetetracarboxylic dianhydride such as 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 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. Further, a cycloaliphatic tetracarboxylic dianhydride and an acyclic aliphatic tetracarboxylic dianhydride may be used in combination.

  Among the above-mentioned 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 lowering 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 dianhydride and mixtures thereof are preferred, and 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride (BPDA) and 4,4'-(hexafluoroisopro Isopropylidene) diphthalic acid dianhydride (6FDA), and more preferably mixtures thereof, 4,4 '- (hexafluoro isopropylidene) diphthalic anhydride are 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。］ It is preferable that the polyamideimide resin A has at least a structural unit in which Y in the formula (4) is derived from a tetracarboxylic dianhydride represented by the formula (4g ′). In this case, at the same time that the film of the present invention has high transparency, the polyamideimide resin A has a high flexibility skeleton, so that the solubility of the polyamideimide resin in the solvent is improved, and the film of the present invention is produced. Since the viscosity of the polyamide imide varnish used at that time can be suppressed to be 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 the 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 1 to carbon atoms. 6 represents an alkyl group, more preferably represents 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. Is also good. In light of the surface hardness and the 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, and particularly preferably. Is a hydrogen atom or a trifluoromethyl group.

［式（４ｇ”）中、＊は結合手を表す。］ In one preferred embodiment described above, the polyamideimide resin A preferably has at least a structural unit in which Y in the formula (4) is derived from a tetracarboxylic dianhydride represented by the formula (4g ″). In this case, at the same time that the film of the present invention has high transparency, the polyamideimide resin A has a skeleton containing a fluorine element, whereby 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 the process can be suppressed to be low, the film of the present invention can be easily produced.

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

  When the polyamide-imide resin A has a structural unit derived from two or more kinds of tetracarboxylic dianhydrides, Y in the formula (4) is a tetravalent group represented by the formula (4g ′), preferably the formula (4g ″). The amount of the structural unit derived from the carboxylic dianhydride is, from the viewpoint of improving the transparency and ease of production of the film, the entire structural unit derived from the tetracarboxylic dianhydride contained in the polyamideimide resin A. Y is preferably at least 50 mol%, more preferably at least 60 mol%, even more preferably at least 70 mol% based on the formula (4g ′), preferably (4g ″). The upper limit of the amount of the structural unit derived from the tetracarboxylic dianhydride represented is not particularly limited, and is 100 based on the entire structural unit derived from the tetracarboxylic dianhydride contained in the polyamideimide resin. And it may be less than or equal to Le%. The ratio of the structural unit derived from the diamine represented by the formula (4g ′) or (4g ″) where X in the formula (4) can be measured, for example, using two-dimensional NMR, or It can also be calculated from the ratio.

The polyamide-imide resin A contained in the film of the present invention may further have a structural unit derived from tricarboxylic acid. Examples of the tricarboxylic acid include an aromatic tricarboxylic acid, an aliphatic tricarboxylic acid, and acid chloride compounds and acid anhydrides which are analogs thereof. One type of tricarboxylic acid may be used, or two or more types may be used in combination. Specific examples include anhydrides of 1,2,4-benzenetricarboxylic acid; 2,3,6-naphthalenetricarboxylic acid-2,3-anhydride; a single bond of phthalic anhydride and benzoic acid; _{, -CH 2 -, - C (} CH 3) 2 -, - C (CF 3) 2 -, - SO 2 - or a compound linked 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 comprises dicarboxylic acid (an analog of dicarboxylic acid such as acid chloride), diamine and tetracarboxylic acid (acid chloride, tetracarboxylic dianhydride). And the like, and optionally with a tricarboxylic acid (an analog of a tricarboxylic acid compound such as an acid chloride compound or a tricarboxylic anhydride). In this embodiment, the polyamide-imide resin A has a structural unit represented by the formula (5) and a structural unit represented by the following formula (6).

[In the formula (5), X and Y are as defined above. ]

[In the formula (6), X and Z are as defined above. ]
X, Y and Z in the formulas (5) and (6) have the same meanings as X in the formula (3), Y in the formula (4) and Z in the formula (2), respectively. The preferable description described above with respect to X, Y and Z in 2) to (4) similarly applies to X, Y and Z in formulas (5) and (6). The structural unit represented by the formula (5) is usually a structural unit derived from a diamine and a tetracarboxylic acid, and the structural unit represented by the formula (6) is generally a structural unit derived from a diamine and a dicarboxylic acid. It 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 the formula (7) and / or a structural unit represented by the following formula (8). May have.

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

[In the formula (8), X ² represents a divalent organic group, and Y ² represents a trivalent organic group. ]

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

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

In the formulas (7) and (8), X ¹ and X ² are each independently a divalent organic group, preferably a hydrocarbon in which a hydrogen atom in the organic group is a hydrocarbon group or a fluorine-substituted hydrocarbon. An organic group which may be substituted with a group. X ¹ and X ² are groups represented by the formulas (3a) to (3i); hydrogen atoms in the groups represented by the formulas (3a) to (3i) are a methyl group, a fluoro group, and a chloro group. 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 comprises a structural unit represented by the formula (5) and the formula (6), and optionally a formula (7) and / or a formula (7) It is composed of the structural unit represented by 8). In this embodiment, from the viewpoint of easily increasing the flexibility and surface hardness of the film, the amounts of the structural units represented by the formulas (5) and (6) included in the polyamideimide resin A are determined by the formulas (5) and (6). 6), and optionally 80% or more, more preferably 90% or more, and still more preferably 95% or more, based on all the structural units represented by the formulas (7) and (8). The upper limit of the amount of the structural units represented by the formulas (5) and (6) contained in the polyamideimide resin A is determined by the formulas (5) and (6), and optionally the formulas (7) and (6). It is usually 100% or less based on all the structural units represented by the formula (8). The ratio can be measured using, for example, two-dimensional NMR, or can be calculated from the charge ratio of the raw materials.

    The glass transition temperature Tg of the polyamideimide resin A contained in the film of the present invention calculated by tan δ in dynamic viscoelasticity measurement (DMA measurement) is preferably less than 380 ° C., more preferably 379 ° C. or less, and further preferably It is 378 ° C or less, for example, 370 ° C or less. When the glass transition temperature Tg of the polyamide-imide resin A is lower than the upper limit or lower than the upper limit, the film of the present invention easily exhibits high surface hardness, and at the same time, easily reduces the elastic modulus and easily increases flexibility. . The lower limit of the glass transition temperature Tg is not particularly limited, but is usually 300 ° C. or higher. The method of calculating the glass transition temperature from tan δ in the dynamic viscoelasticity measurement (DMA measurement) can be specifically performed as in the examples.

  The weight average molecular weight (Mw) of the polyamide imide resin A contained in the film of the present invention is preferably 5,000 or more, more preferably 10,000 or more, further preferably 50,000 or more, and particularly preferably 70,000 or more. , 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 lower limit described above, the film of the present invention is likely to have higher bending resistance. When the weight average molecular weight (Mw) of the polyamide imide resin A is equal to or less than the above upper limit, the solubility of the polyamide imide resin in the solvent is improved, and the viscosity of the polyamide imide varnish used when producing the film of the present invention is reduced. Since it can be suppressed low, the film of the present invention can be easily manufactured. Further, since the film can be easily stretched, the workability is good. The weight average molecular weight (Mw) can be determined, for example, by performing GPC measurement and converting it to standard polystyrene, and specifically, it can be determined by the method described in Examples.

  The polyamide imide resin A contained in the film of the present invention preferably contains a halogen atom, and more preferably contains a fluorine atom. Specific examples of the fluorine-containing substituent include a fluoro group and a trifluoromethyl group. When the polyamideimide resin A contains a halogen atom, the yellowness (YI value) of the film of the present invention is easily reduced, and it is easy to achieve both higher flexibility and flex resistance. The halogen atom is preferably a fluorine atom from the viewpoints of reducing the yellowness (improving transparency), reducing the water absorption and bending resistance of the film of the present invention. From the above viewpoint, the polyamideimide resin A preferably has at least a structural unit derived from a fluorine atom-containing diamine and / or a fluorine atom-containing tetracarboxylic dianhydride.

  The content of the halogen atom in the polyamide-imide resin A is determined based on the mass of the polyamide-imide resin A contained in the film of the present invention, from the viewpoints of reducing yellowness (improving transparency), reducing water absorption, and suppressing deformation of the film. Is preferably 1 to 40% by mass, more preferably 3 to 35% by mass, and still 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 polyamideimide resin. Examples of the additive having a light absorption function include an ultraviolet absorber and a bluing agent. It is preferable that the additive having a light absorbing function is selected from the group consisting of an ultraviolet absorber and a bluing agent because the visibility and quality of the film of the present invention are easily improved. The film of the present invention may contain one kind of additive having a light absorbing function, or may contain two or more kinds of additives having a light absorbing function. Here, when an additive having a light absorbing function such as an ultraviolet absorber and a bluing agent is added to a film containing a conventional polyamideimide resin, these additives have low heat resistance. There is a problem that decomposition and the like occur in the step of heating the containing film under a high temperature condition, and the quality of the film is deteriorated. Therefore, for example, it was necessary to add such additives to a layer different from the layer containing the polyamide-imide resin, and to adhere the additive to a polyamide-imide film. For example, when a film is produced 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 ratio of the polyamideimide resin contained in the resin composition is increased in advance. Can be kept. Therefore, even when the film is manufactured under relatively low temperature heating conditions, the imidization ratio can be increased, and a sufficiently high surface hardness can be achieved. Therefore, even when additives having a light absorbing function are added to the same layer as the layer containing the polyamide-imide resin, decomposition of these additives and the like can be suppressed, and deterioration in film quality can be suppressed.

  The ultraviolet absorber may be appropriately selected from those commonly used as ultraviolet absorbers in the field of resin materials. The ultraviolet absorber may include a compound that absorbs light having 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 polyamideimide resin is suppressed, so that the visibility of the film can be improved. In this specification, the “system compound” refers to a derivative of the compound to which the “system compound” is attached. For example, “benzophenone-based compound” refers to a compound having benzophenone as a parent skeleton and a substituent bonded to 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 the ultraviolet absorber to be used, but as a guide, based on the total weight of the film, preferably 1 mass % Or more, more preferably 2% by mass or more, still more preferably 3% by mass or more, preferably 10% by mass or less, more preferably 8% by mass or less, and still more preferably 6% by mass or less. The preferred amount of addition varies depending on the ultraviolet absorber used, but adjusting the amount of addition so that the light transmittance at 400 nm is about 20 to 60% can easily enhance the light resistance of the film of the present invention and can improve the transparency. This is preferable because it is easy to obtain a film having a high film thickness.

  The bluing agent may be appropriately selected from those commonly used as bluing agents in the field of resin materials. The 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, and includes, for example, ultramarine, navy blue, cobalt blue, and the like. Inorganic dyes and pigments, for example, 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 the condensed polycyclic bluing agent 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 the bluing agent may be appropriately selected depending on the kind of the bluing agent to be used. 01 mass% or more, more preferably 0.02 mass% or more, still more preferably 0.03 mass% or more, preferably 1.0 mass% or less, more preferably 0.5 mass% or less, and still more preferably 0 mass% or less. 0.2 mass% or less.

  The film of the present invention may further contain an inorganic material such as inorganic particles in addition to the polyamideimide resin. Examples of the inorganic material 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 linked by a molecule having a siloxane bond.

  The average primary particle diameter of the inorganic particles is preferably from 10 to 100 nm, more preferably from 20 to 80 nm, from the viewpoints of transparency and mechanical properties of the film and suppression of aggregation of the inorganic particles. In the present invention, the average primary particle diameter can be determined by measuring ten points in a fixed direction with a transmission electron microscope (TEM) and calculating the average value thereof.

  When the film of the present invention contains an inorganic material, the content of the inorganic material in the film is preferably from 0 to 90% by mass, more preferably from 0 to 60% by mass, and still more preferably 0 to 90% by mass, based on the total mass of the film. ４０40% by mass. When the content of the inorganic material is within the above range, the transparency and mechanical properties of the film tend to be compatible.

  The film of the present invention may contain other additives. Other additives include, for example, antioxidants, release agents, stabilizers, flame retardants, pH adjusters, silica dispersants, lubricants, thickeners, leveling agents, and the like. When the film of the present invention contains another additive, the content of the other additive is preferably from 0% by mass to 20% by mass, more preferably 0% by mass, based on the mass of the film of the present invention. Not less than 10% by mass.

(Layer structure)
The layer configuration of the film of the present invention is not particularly limited, and may be a single layer or a multilayer of two or more layers. When the film of the present invention further contains an additive such as an additive having a light absorbing function, from the viewpoint of reducing the thickness of the image display device and economy, the additive and the polyamideimide resin are combined into one layer. It is preferred 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 polyamideimide resin. When the film of the present invention further contains an additive such as an additive having a light absorbing 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 polyamideimide resin.

  The film of the present invention may be a polyamide-imide laminate in which one or more functional layers are further laminated on the above layer. Examples of the functional layer 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. The film of the present invention may have one or more functional layers. Further, one functional layer may have a plurality of functions. For example, a film having a multilayer structure may be obtained by forming the functional layer on a film containing a polyamideimide 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 imidation ratio of 60% or more as measured by two-dimensional NMR. And a resin composition containing at least a polyamideimide resin B having a solvent and a solvent. The film of the present invention containing the polyamide-imide resin A is produced, for example, using the resin composition of the present invention containing at least the polyamide-imide resin B and a solvent.

  The resin composition of the present invention contains a polyamideimide resin B having an imidization ratio 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 polyamide-imide resin, and contains a polyamide-imide resin B having a high imidation ratio as described above. Can sufficiently increase the imidization ratio of the polyamideimide resin contained in the resin, and as a result, a polyamideimide film having a sufficiently high surface hardness can be obtained. When the imidation ratio of the polyamideimide resin contained in the resin composition is lower than 60%, the polyamideimide having an excessively flexible primary structure tends to have a primary structure. Can not be increased. From the viewpoint of surface hardness, the imidization ratio of the polyamide-imide resin B is preferably 80% or more, more preferably 90% or more, and even more preferably 95% or more. The higher the imidization ratio, the better. The upper limit is not particularly limited, and may be 100% or less.

  The imidation ratio of the polyamide-imide resin B is the ratio of the number of moles of the imide bond in the polyamide-imide resin B to the value of twice the number of moles of the structural unit derived from the tetracarboxylic dianhydride in the polyamide-imide resin B. Which is measured by two-dimensional NMR in this specification. The imidation rate of the polyamide-imide resin B is determined by dissolving the polyamide-imide resin B precipitated and dried by reprecipitation by adding a poor solvent to the resin composition (varnish) in deuterated dimethyl sulfoxide (DMSO-d6). The measurement can be performed using two-dimensional NMR with the predetermined solution obtained as a measurement sample.

  Examples of the poor solvent include an alcohol solvent, water, a saturated hydrocarbon solvent, an aromatic solvent, and the like, and preferably include an alcohol solvent and water. Examples of 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, glycerin and the like, preferably methanol, ethanol, 1-propanol and 2-propanol, more preferably methanol and ethanol. Further, two or more of these poor solvents may be mixed.

The imidation ratio is represented by the formula (9).

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

  In order to obtain an imidation ratio with high accuracy, a conventionally known or commonly used technique is applied. Such techniques include, for example, increasing the signal-to-noise (S / N) ratio and accurately integrating the resulting two-dimensional NMR spectrum. In order to obtain the imidation ratio with higher accuracy, the S / N ratio is preferably 6 or more. Examples of methods for increasing the S / N ratio include increasing the sample concentration, increasing the number of integrations, and using a highly sensitive NMR measurement device. Examples of a highly sensitive NMR measurement apparatus include an NMR apparatus having a stronger magnetic field and an NMR apparatus using a cryoprobe. In addition, examples of a method of accurately integrating a two-dimensional NMR spectrum include performing phase correction and performing baseline correction. Further, when signals on a two-dimensional NMR spectrum derived from a different structure from the repeating unit having an amic acid and the repeating unit having an imide bond overlap with each other, the signal can be accurately integrated by excluding the intensity of the signal. An imidization rate can be obtained.

  The glass transition temperature Tg of the polyamideimide resin B calculated by tan δ in dynamic viscoelasticity measurement (DMA measurement) is preferably less than 380 ° C, more preferably 379 ° C or less, further preferably 378 ° C or less, for example, 370 ° C. It is as follows. When the glass transition temperature Tg of the polyamide-imide resin B is less than the above upper limit or equal to or less than the above upper limit, in the film obtained by using the resin composition of the present invention, it is easy to exhibit high surface hardness, and at the same time, the elastic modulus is increased. It is easy to drop and increase flexibility. The lower limit of the glass transition temperature Tg is not particularly limited, but is usually 300 ° C. or higher. The method of calculating the glass transition temperature from tan δ in the dynamic viscoelasticity measurement (DMA measurement) can be specifically performed as in the 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, further preferably 50,000 or more, and particularly preferably 70,000 or more. , 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 lower limit described above, the film obtained using the resin composition of the present invention can easily increase the bending resistance. When the weight average molecular weight (Mw) of the polyamide-imide resin B is equal to or less than the upper limit, the solubility of the polyamide-imide resin in a solvent is improved, and the viscosity of the resin composition of the present invention can be suppressed to be low. Films are easier to manufacture. Further, since the film can be easily stretched, the workability is good. The weight average molecular weight (Mw) can be determined, for example, by performing GPC measurement and converting it to standard polystyrene, and specifically, it can be determined by the method described in Examples.

  The polyamide imide resin B contained in the resin composition of the present invention has a constituent unit derived from a diamine, a constituent unit derived from a dicarboxylic acid, and a constituent unit derived from a tetracarboxylic dianhydride. Regarding specific examples and preferred embodiments of the diamine, dicarboxylic acid and tetracarboxylic dianhydride, the above description regarding the polyamideimide resin A similarly applies. The polyamide imide resin B contained in the resin composition of the present invention may also have a structural unit derived from a tricarboxylic acid, similarly to the polyamide imide resin A. As for the tricarboxylic acid, the above description regarding the polyamideimide resin A similarly applies.

［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 contains dicarboxylic acid (an analog of dicarboxylic acid such as acid chloride), diamine and tetracarboxylic acid (acid chloride, tetracarboxylic acid dicarboxylic acid). It is a condensation polymer which is a polycondensation product with a tetracarboxylic acid analog such as an anhydride) and optionally with a tricarboxylic acid (an acid chloride compound or a tricarboxylic acid analog such as a tricarboxylic anhydride). . In this embodiment, the polyamide-imide resin B has a structural unit represented by the formula (5) and a structural unit represented by the formula (6), similarly to the polyamide-imide resin A.

[In the formula (5), X and Y are as defined above. ]

[In the formula (6), X and Z are as defined above. ]
X, Y and Z in the formulas (5) and (6) have the same meanings as X in the formula (3), Y in the formula (4) and Z in the formula (2), respectively. The preferable description described above with respect to X, Y and Z in 2) to (4) similarly applies to X, Y and Z in formulas (5) and (6). The structural unit represented by the formula (5) is usually a structural unit derived from a diamine and a tetracarboxylic acid, and the structural unit represented by the formula (6) is generally a structural unit derived from a diamine and a dicarboxylic acid. It 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 further comprises a structural unit represented by the formula (7) and / or a structural unit represented by the following formula (8) It may have a unit.

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

[In the formula (8), X ² represents a divalent organic group, and Y ² represents a trivalent organic group. ]

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

In the formula (8), Y ² is each independently a trivalent organic group, and preferably a hydrogen atom in the organic group may be substituted with a hydrocarbon group or a fluorine-substituted hydrocarbon group. Organic group. The organic group is preferably a trivalent organic group having 4 to 40 carbon atoms. The hydrocarbon group and the fluorine-substituted hydrocarbon group preferably have 1 to 8 carbon atoms. Further, the organic group preferably has 4 to 40 carbon atoms. Y ² is a group in which any one of the bonds of the groups represented by the above formulas (4a) to (4j) is replaced by a hydrogen atom, and a trivalent chain hydrocarbon group having 6 or less carbon atoms. Is exemplified. The polyamide-imide resin B may have one type of the structural unit represented by the formula (8), or is represented by two or more types of the formula (7) different from each other in Y ² and / or X ² . It may have a structural unit. The example of W ^{1 in} the formula is the same as the example of W ^{1 in} the description about Y ¹ .

In the formulas (7) and (8), X ¹ and X ² are each independently a divalent organic group, preferably a hydrocarbon in which a hydrogen atom in the organic group is a hydrocarbon group or a fluorine-substituted hydrocarbon. An organic group which may be substituted with a group. The organic group is preferably a divalent organic group having 4 to 40 carbon atoms. The hydrocarbon group and the fluorine-substituted hydrocarbon group preferably have 1 to 8 carbon atoms. Further, the organic group preferably has 4 to 40 carbon atoms. X ¹ and X ² are groups represented by the formulas (3a) to (3i); hydrogen atoms in the groups represented by the formulas (3a) to (3i) are a methyl group, a fluoro group, and a chloro group. 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 polyamide imide resin B contained in the resin composition of the present invention contains structural units represented by the formulas (5) and (6), and optionally the formula (7) and / or It consists of the structural unit represented by the formula (8). In this embodiment, from the viewpoint of easily increasing the flexibility and surface hardness of the film, the amounts of the structural units represented by the formulas (5) and (6) included in the polyamideimide resin B are determined by the formulas (5) and (6). 6), and optionally 80% or more, more preferably 90% or more, and still more preferably 95% or more, based on all the structural units represented by the formulas (7) and (8). The upper limit of the amount of the structural units represented by the formulas (5) and (6) contained in the polyamideimide resin B is determined by the formulas (5) and (6), and optionally the formulas (7) and (6). It is usually 100% or less based on all the structural units represented by the formula (8). The ratio can be measured using, for example, two-dimensional NMR, or can be calculated from the charge ratio of the raw materials.

  The polyamide-imide resin B contained in the resin composition of the present invention preferably contains a halogen atom as in the case of the polyamide-imide resin A, and more preferably contains a fluorine atom. Specific examples of the fluorine-containing substituent include a fluoro group and a trifluoromethyl group. When the polyamideimide resin B contains a halogen atom, the yellowness (YI value) of the film obtained by using the resin composition of the present invention is easily reduced, and it is easy to achieve both high flexibility and bending resistance. The halogen atom is preferably a fluorine atom from the viewpoints of reducing the yellowness of the film (improving transparency), reducing the water absorption, and bending resistance. From the above viewpoint, the polyamideimide resin B preferably has at least a structural unit derived from a fluorine atom-containing diamine and / or a fluorine atom-containing tetracarboxylic dianhydride.

  The content of the halogen atom in the polyamide-imide resin B is selected from the viewpoints of reducing yellowness (improving transparency), reducing water absorption, and suppressing deformation of the film. Is preferably 1 to 40% by mass, more preferably 3 to 35% by mass, and still more preferably 5 to 32% by mass, based on the mass of

  The solvent contained in the resin composition of the present invention is not particularly limited as long as the polyamideimide resin B can be dissolved. Examples of such a solvent include amide solvents such as N, N-dimethylacetamide (DMAc) and N, N-dimethylformamide; lactone solvents such as γ-butyrolactone and γ-valerolactone; dimethyl sulfone, dimethyl sulfoxide, sulfolane and the like. A carbonate-based solvent such as ethylene carbonate and propylene carbonate; and a combination thereof (mixed solvent). Among these solvents, amide solvents or lactone solvents are preferred, and solvents containing dimethylacetamide are more preferred. Further, the polyamideimide 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 can be included in the above-described film of the present invention.

  Next, a method for producing the polyamide-imide resin A contained in the film of the present invention and the polyamide-imide resin contained in the resin composition of the present invention B will be described. The polyamide imide resin A and the polyamide imide resin B are, for example, copolymerized (polycondensed) with the above-mentioned dicarboxylic acid, diamine and tetracarboxylic acid as main raw materials, optionally together with the above-mentioned tricarboxylic acid. Can be manufactured.

The method for producing the polyamide-imide resin A contained in the film of the present invention and the polyamide-imide resin B contained in the resin composition of the present invention is not particularly limited as long as a polyamide-imide 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 polyamide-imide resin precursor; and
(2) It can be manufactured 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 polyamide-imide resin precursor; and
(2) At least a step of adding a dehydrating agent and a tertiary amine to a solution containing at least a polyamide-imide resin precursor and heating at a temperature of 70 to 120 ° C., in a solvent at the start of step (1) If the amount of water is w (ppm) and the heating time in the step (2) is t (minutes), a method for producing a polyamideimide resin in which w and t satisfy the following formula is also provided.

  The polyamide-imide resin obtained by the production method of the present invention may be, for example, a polyamide-imide resin A or a polyamide-imide resin B, and the above description for the polyamide-imide resin A and the polyamide-imide resin B similarly applies. In addition, it is also possible to obtain the resin composition of the present invention by the production method of the present invention and produce the film of the present invention using the resin composition.

  In this embodiment, the polyamide-imide resin obtained by the production method of the present invention and the polyamide-imide resin B contained in the resin composition of the present invention are the same resin. Further, the polyamide-imide resin B contained in the resin composition of the present invention and the polyamide-imide resin A contained in the film of the present invention may be the same resin in the imidation ratio and the constituent units of the resin. Resins different in imidation ratio may be used.

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

  In the step (1), an imidization catalyst may be used. Examples of the imidization catalyst include aliphatic amines such as tripropylamine, dibutylpropylamine, and 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 such as nonane (polycyclic); and pyridine, 2-methylpyridine, 3-methylpyridine, 4-methylpyridine, 2-ethylpyridine, 3-ethylpyridine, 4-ethylpyridine, 2, 4-dimethylpyridine, 2,4,6-trimethylpyridine, 3,4-cyclopentenopyridine 5,6,7,8-tetrahydroisoquinoline, and include aromatic amines isoquinoline.

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

  The dehydrating agent used in the step (2) is a substance capable of promoting the copolymerization of a diamine, a dicarboxylic acid, and a tetracarboxylic dianhydride, which are polycondensation reactions accompanied by dehydration, in a solvent. Examples of the dehydrating agent include acetic anhydride, propionic anhydride, isobutyric anhydride, pivalic anhydride, butyric anhydride, isovaleric anhydride and the like. Preferably, the dehydrating agent is 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 the tertiary amine include, for example, the aforementioned aromatic amines and aliphatic amines. Preferably, the tertiary amine is 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, assuming that the amount of water in the solvent at the start of the step (1) is w (ppm) and the heating time in the step (2) is t (min), w and t are represented by the following formulas. Meet.

1 / t (w + 167) is preferably 5.0 or less, more preferably 4.0 or less, and still more preferably 3.0 or less. Copolymerization of a diamine, dicarboxylic acid, and tetracarboxylic dianhydride in a solvent for producing a polyamideimide resin is a polycondensation reaction involving dehydration. Therefore, the polycondensation reaction (especially the imidization reaction) can proceed efficiently by reducing the amount of water present in the reaction system or adjusting the heating time, and as a result, the resulting product is obtained. The imidization ratio in the polyamide-imide resin can be increased. Therefore, according to the above-mentioned production method of the present invention, it is possible to produce a polyamide-imide resin having a higher imidation ratio than before. Note that it is difficult to sufficiently increase the imidization ratio of the polyamide-imide resin by the conventionally known manufacturing method. Therefore, a process of preparing a film using a polyamide imide varnish containing a polyamide imide resin having a relatively low imidation ratio and heating the film under a high temperature condition to progress imidation is performed. However, as described above, when heating is performed in the state of a film to increase the imidization ratio, a sufficiently high imidization ratio cannot be achieved, sufficient surface hardness cannot be obtained, and heating conditions In some cases, the imidization ratio of the polyamide-imide resin varies, and the imidization ratio is not stable. ADVANTAGE OF THE INVENTION According to the manufacturing method of this invention, the imidation rate of a polyamide imide resin can be easily increased sufficiently at the synthesis | combination stage before processing into a film, and the above-mentioned problem is solved.

  The production method of the present invention is not particularly limited as long as it includes at least the step (1) and the step (2). As a method for producing a resin composition containing a polyamide-imide resin obtained by the production method of the present invention, for example, a mixed solution containing the polyamide-imide resin obtained in the step (1) and the step (2) is further added with a solvent and By adding an additive 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. A poor solvent is added to the mixed solution containing the polyamide-imide resin obtained in the step (2) to precipitate the polyamide-imide resin by a reprecipitation method, dried and taken out as a precipitate, and the taken-out polyamide-imide resin precipitate is dissolved in a solvent. Thus, a resin composition containing at least a polyamideimide resin and a solvent may be obtained.

The film of the present invention comprises, for example, (1) a step of applying the polyamideimide resin composition obtained as described above to a support, and
(2-1) a step of removing a coating film of the composition from a support after drying, or
(2-2) The composition can be produced by a production method including at least a step of drying a coating film of the composition from a 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 polyamideimide resin composition obtained as described above.

  For example, by forming a coating film of a polyamideimide varnish by applying a polyamideimide varnish on a support such as a resin substrate, a SUS belt, or a glass substrate by a known roll-to-roll or batch method. Can be. Examples of the support include a PET film, a PEN film, a polyimide film, and a polyamideimide film. Among them, a PET film, a PEN film, a polyimide film, and another polyamideimide film are preferable from the viewpoint of excellent heat resistance. From the viewpoints of adhesion to the film of the present invention and cost, a PET film is more preferable.

  Next, in the step (2-1) or the step (2-2), the coating film of the polyamideimide varnish is dried, and after the drying, the coating is separated from the support. Drying of the coating film can be performed at a temperature of preferably 50 to 240 ° C, more preferably 200 to 240 ° C. If necessary, the coating film may be dried under an inert atmosphere or under reduced pressure. By peeling the coating film from the support after drying, the film of the present invention can be obtained. As described in the step (2-2), a step of further heating the peeled film may be performed, for example, 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.

  A surface treatment step of performing a surface treatment on at least one surface of the film manufactured as described above may be performed. Examples of the surface treatment include UV ozone treatment, plasma treatment, and corona discharge treatment.

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

  The film of the present invention may further include a functional layer. Examples of the functional layer 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. The film of the present invention may have one or more functional layers. Further, one functional layer may have a plurality of functions.

  The hard coat layer is preferably disposed on the viewing side surface of the film. The hard coat layer may have a single-layer structure or a multilayer structure. The hard coat layer contains a hard coat layer resin. Examples of the hard coat layer resin include an acrylic resin, an epoxy resin, a urethane resin, a benzyl chloride resin, a vinyl resin, a silicone resin, or a mixture thereof. Examples of the resin include an ultraviolet curable resin, an electron beam curable resin, and a thermosetting resin such as a resin. In particular, the hard coat layer preferably contains an acrylic resin from the viewpoint of mechanical properties such as surface hardness and the like, and from an industrial viewpoint. In one preferred embodiment of the present invention, the film of the present invention has a high surface hardness, and therefore has a sufficient surface hardness for use in an image display device or the like without a hard coat layer. For this reason, 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 light, for example, a main material selected from an ultraviolet-curable transparent resin, an electron beam-curable transparent resin, and a thermosetting transparent resin, and the main material And a dispersed ultraviolet absorber. By providing an ultraviolet absorbing layer as a functional layer, a change in yellowness due to light irradiation can be easily suppressed.

  The adhesive layer is a layer having an adhesive function, and has a function of bonding the film of the present invention to another member. As a material for forming the adhesive layer, a generally known material can be used. 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 constituting the adhesive layer after the film is brought into close contact with another member. The adhesive strength between the film of the present invention and the pressure-sensitive adhesive layer may be 0.1 N / cm or more, or 0.5 N / cm or more.

  The adhesive layer may include 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 after the fact.

  The pressure-sensitive adhesive layer may be a layer composed of an adhesive called a pressure-sensitive adhesive (Pressure Sensitive Adhesive, PSA), which is attached to an object by pressing. The pressure-sensitive adhesive may be a pressure-sensitive adhesive that is “a substance that is tacky at room temperature and adheres to an adherend with light pressure” (JIS K6800), and “a protective film (microcapsule) containing a specific component”. And an adhesive capable of maintaining stability until the film is broken by an appropriate means (pressure, heat, etc.) (JIS K6800).

  The hue adjustment layer is a layer having a hue adjustment function, and is a layer that can adjust the film of the present invention to a desired hue. The hue adjustment layer is a layer containing, for example, a resin and a colorant. Examples of the coloring agent include inorganic pigments such as titanium oxide, zinc oxide, red iron oxide, baked titanium oxide pigment, ultramarine, cobalt aluminate, and carbon black; azo compounds, quinacridone compounds, anthraquinone compounds, Organic pigments such as perylene compounds, isoindolinone compounds, phthalocyanine compounds, quinophthalone compounds, sulene 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 polyamideimide 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 be. The refractive index adjustment layer may be, for example, a resin layer containing an appropriately selected resin and optionally a pigment, or may be a thin metal film.

  Examples of the pigment for adjusting the refractive index include 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. When the average primary particle diameter of the pigment is 0.1 μm or less, irregular reflection of light passing through the refractive index adjusting layer can be prevented, and a decrease in transparency can be prevented.

  Examples of the metal used for the refractive index adjustment 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 are mentioned.

  The film of the present invention is an optical film useful as, for example, a front plate of an image display device, particularly a front plate (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 plate has a function of protecting the image display element in the flexible display.

  Examples of the image display device include a wearable device such as a television, a smartphone, a mobile phone, a car navigation, a tablet PC, a portable game machine, an electronic paper, an indicator, a bulletin board, a clock, and a smart watch. Examples of the flexible display include the above-described image display devices having flexible characteristics.

  Hereinafter, the present invention will be described in more detail with reference to examples. "%" And "parts" in the examples mean% by mass and parts by mass unless otherwise specified. First, the evaluation method will be described.

<Measurement of weight average molecular weight (Mw)>
The weight average molecular weight (Mw) of the polyamideimide resin was determined by gel permeation chromatography (GPC) measurement in terms of standard polystyrene. Specific measurement conditions were as follows.
(1) Pretreatment method A DMF eluent (10 mM lithium bromide solution) was added to the obtained polyamideimide resin so as to have a concentration of 2 mg / mL, and the mixture was heated with stirring at 80 ° C for 30 minutes. The solution obtained by filtration using a membrane filter having an opening of 0.45 μm was used as a measurement solution.
(2) Measurement condition column: TSKgel SuperAWM-H × 2 + SuperAW2500 × 1 (6.0 mm ID × 150 mm × 3) (all manufactured by Tosoh Corporation)
Eluent: DMF (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 a DMA Q800 manufactured by TA Instrument, measurement was performed under the following samples and conditions to obtain a tan δ curve which is a ratio of a value of a loss modulus to a value of a storage modulus. The Tg of the polyamideimide 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
Experimental mode detailed conditions:
(1) Clamp: Tension: Film
(2) Amplitude: 5 μm
(3) Frequency: 10 Hz (no change in all temperature sections)
(4) Preload Force: 0.01N
(5) Force Track: 125N
Temperature conditions: (1) Heating range: room temperature to 400 ° C, (2) Heating rate: 5 ° C / min Main collected data: (1) Storage modulus (E '), (2) Loss modulus (Loss modulus, E "), (3) tan δ (E" / E ')

<Measurement of imidation ratio>
The imidation ratio of the polyimide resin and the polyamideimide resin used in Examples and Comparative Examples was measured by NMR, and was calculated using a signal derived from the partial structure shown in Formula (10). The method of calculating the imidation ratio from the measurement conditions and the obtained results is as follows.

(Method for preparing measurement sample)
Polyamide imide resin B:
A resin obtained by adding a large excess of methanol as a poor solvent to a resin composition (varnish) containing at least a solvent, and precipitating and drying by reprecipitation method, is dissolved in deuterated dimethyl sulfoxide (DMSO-d6). A 2% by weight solution was used as a measurement sample.
Polyamide imide resin A:
A film containing the resin was dissolved in deuterated dimethyl sulfoxide (DMSO-d6) to form a 2% by mass solution, which was used as a measurement sample.

(NMR measurement conditions)
Measuring device: Bruker 600MHz NMR device AVANCE600
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。 (Method of calculating imidation ratio of polyimide resin)
In a ¹ H-NMR spectrum obtained using a solution containing a polyimide resin as a measurement sample, the integral value of the signal derived from the proton (A) in the formula (10) is represented by Int _A and the integral value of the signal derived from the proton (B). The value was Int _B. From these values, the imidation ratio (%) was determined by the following formula (NMR-1).

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

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

Then, in an HSQC spectrum obtained using a solution containing a polyamideimide resin as a measurement sample, a β value was determined by the formula (NMR-2) in the same manner as described above. By substituting this β value into the above-mentioned correlation formula (NMR-3), the imidation ratio (%) of the polyamideimide resin was obtained.

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

<Measurement of yellowness (YI value)>
The yellow 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 in the absence of the sample, the sample was set on a sample holder, and the transmittance for light having a wavelength of 300 to 800 nm was measured to determine the tristimulus values (X, Y, Z). The YI value was calculated based on the following equation.

<Measurement of surface hardness>
The pencil hardness of the sample surface was measured as the surface hardness of the obtained polyamideimide film in accordance with JIS K5600-5-4: 1999. The measurement was performed under the conditions of a load of 100 g and a scanning speed of 60 mm / min, and the evaluation was made under the illuminance condition of the light amount of 4,000 lux to evaluate the presence or absence of a scratch, and the pencil hardness was determined.

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

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

[Example 1]
In a 1 L separable flask equipped with a stirring blade under a nitrogen atmosphere, 52 g (162.38 mmol) of 2,2′-bis (trifluoromethyl) benzidine (TFMB) and N, N-dimethylacetamide adjusted to have a water content of 500 ppm were added. (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. 9.57 g (32.52 mmol) of (BPDA) was added, and the mixture was stirred at room temperature for 3 hours. Thereafter, 13.21 g (63.10 mmol) of terephthaloyl chloride (TPC) was added to the flask, and the mixture was 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 the mixture was stirred at room temperature for 30 minutes, and then heated to 70 ° C. using an oil bath. After stirring for an hour, a reaction solution was obtained.
The obtained reaction solution was cooled to room temperature, poured into a large amount of methanol in a thread form, 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 polyamideimide resin.
DMAc was added to the obtained polyamide-imide resin so as to have a concentration of 15% by mass to prepare a polyamide-imide varnish. The obtained polyamideimide varnish is applied on a smooth surface of a polyester base material (trade name “A4100”, manufactured by Toyobo Co., Ltd.) using an applicator so that the thickness of the self-standing film is 55 μm, and is applied at 50 ° C. 30 After drying at 140 ° C. for 15 minutes, a free-standing film was obtained. The self-standing film was fixed on a metal frame, and further dried at 300 ° C. for 30 minutes in the air to obtain a polyamideimide film having a 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 heating at 70 ° C. was changed to 1 hour to obtain a polyamideimide resin, A polyamide imide film was obtained.

[Example 3]
In a 1 L separable flask equipped with a stirring blade under a nitrogen atmosphere, 52 g (162.38 mmol) of 2,2′-bis (trifluoromethyl) benzidine (TFMB) and N, N-dimethylacetamide adjusted to have a water content of 500 ppm were added. (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 the mixture was stirred at room temperature for 3 hours. Thereafter, 19.81 g (97.57 mmol) of terephthaloyl chloride (TPC) was added to the flask, and the mixture was stirred at room temperature for 1 hour. Next, 7.49 g (94.65 mmol) of pyridine and 14.61 g (143.11 mmol) of acetic anhydride were added to the flask, and the mixture was stirred at room temperature for 30 minutes. Then, the temperature was raised to 70 ° C. using an oil bath. After stirring for an hour, a reaction solution was obtained.
The obtained reaction solution was cooled to room temperature, poured into a large amount of methanol in a thread form, 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 polyamideimide resin.
DMAc was added to the obtained polyamide-imide resin so as to have a concentration of 15% by mass to prepare a polyamide-imide varnish. The obtained polyamideimide varnish is applied on a smooth surface of a polyester base material (trade name “A4100”, manufactured by Toyobo Co., Ltd.) using an applicator so that the thickness of the self-standing film is 55 μm, and is applied at 50 ° C. 30 After drying at 140 ° C. for 15 minutes, a free-standing film was obtained. The self-standing film was fixed on a metal frame, and further dried at 300 ° C. for 30 minutes in the air to obtain a polyamideimide film having a thickness of 50 μm.

[Example 4]
In a 1 L separable flask equipped with a stirring blade under a nitrogen atmosphere, 52 g (162.38 mmol) of 2,2′-bis (trifluoromethyl) benzidine (TFMB) and N, N-dimethylacetamide adjusted to have a water content of 500 ppm were added. (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 the mixture was stirred at room temperature for 3 hours. Thereafter, 19.81 g (97.57 mmol) of terephthaloyl chloride (TPC) was added to the flask, and the mixture was stirred at room temperature for 1 hour. Next, 7.49 g (94.65 mmol) of pyridine and 14.61 g (143.11 mmol) of acetic anhydride were added to the flask, and the mixture was stirred at room temperature for 30 minutes. Then, the temperature was raised to 70 ° C. using an oil bath. After stirring for an hour, a reaction solution was obtained.
The obtained reaction solution was cooled to room temperature, poured into a large amount of methanol in a thread form, 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 polyamideimide resin.
DMAc was added to the obtained polyamide-imide resin so as to have a concentration of 15% by mass to prepare a polyamide-imide varnish. The obtained polyamideimide varnish is applied on a smooth surface of a polyester base material (trade name “A4100”, manufactured by Toyobo Co., Ltd.) using an applicator so that the thickness of the self-standing film is 55 μm, and is applied at 50 ° C. 30 After drying at 140 ° C. for 15 minutes, a free-standing film was obtained. The self-standing film was fixed on a metal frame, and further dried at 230 ° C. for 30 minutes in the atmosphere to obtain a 50 μm-thick polyamideimide film.

[Example 5]
In a 1 L separable flask equipped with a stirring blade under a nitrogen atmosphere, 52 g (162.38 mmol) of 2,2′-bis (trifluoromethyl) benzidine (TFMB) and N, N-dimethylacetamide adjusted to have a water content of 500 ppm were added. (DMAc) 733.40 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 the mixture was stirred at room temperature for 3 hours. Thereafter, 28.80 g (97.57 mmol) of 4,4′-oxybis (benzoyl chloride) (OBBC) was added to the flask, and the mixture was stirred at room temperature for 1 hour. Next, 7.49 g (94.65 mmol) of pyridine and 14.61 g (143.11 mmol) of acetic anhydride were added to the flask, and the mixture was stirred at room temperature for 30 minutes. Then, the temperature was raised to 70 ° C. using an oil bath. After stirring for an hour, a reaction solution was obtained.
The obtained reaction solution was cooled to room temperature, poured into a large amount of methanol in a thread form, 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 polyamideimide resin.
DMAc was added to the obtained polyamide-imide resin so as to have a concentration of 15% by mass to prepare a polyamide-imide varnish. The obtained polyamideimide varnish is applied on a smooth surface of a polyester base material (trade name “A4100”, manufactured by Toyobo Co., Ltd.) using an applicator so that the thickness of the self-standing film is 55 μm, and is applied at 50 ° C. 30 After drying at 140 ° C. for 15 minutes, a free-standing film was obtained. The self-standing film was fixed on a metal frame, and further dried at 300 ° C. for 30 minutes in the air to obtain a polyamideimide film having a thickness of 50 μm.

[Example 6]
In a 1 L separable flask equipped with a stirring blade under a nitrogen atmosphere, 52 g (162.38 mmol) of 2,2′-bis (trifluoromethyl) benzidine (TFMB) and N, N-dimethylacetamide adjusted to have a water content of 500 ppm were added. (DMAc) 733.40 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 the mixture was stirred at room temperature for 3 hours. Thereafter, 28.80 g (97.57 mmol) of 4,4′-oxybis (benzoyl chloride) (OBBC) was added to the flask, and the mixture was stirred at room temperature for 1 hour. Next, 7.49 g (94.65 mmol) of pyridine and 26.56 g (260.2 mmol) of acetic anhydride were added to the flask, and the mixture was stirred at room temperature for 30 minutes, and then heated to 70 ° C. using an oil bath. After stirring for an hour, a reaction solution was obtained.
The obtained reaction solution was cooled to room temperature, poured into a large amount of methanol in a thread form, 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 polyamideimide resin.
DMAc was added to the obtained polyamide-imide resin so as to have a concentration of 15% by mass to prepare a polyamide-imide varnish. The obtained polyamideimide varnish is applied on a smooth surface of a polyester base material (trade name “A4100”, manufactured by Toyobo Co., Ltd.) using an applicator so that the thickness of the self-standing film is 55 μm, and is applied at 50 ° C. 30 After drying at 140 ° C. for 15 minutes, a free-standing film was obtained. The self-standing film was fixed on a metal frame, and further dried at 300 ° C. for 30 minutes in the air to obtain a polyamideimide film having a thickness of 50 μm.

[Example 7]
In a 1 L separable flask equipped with a stirring blade under a nitrogen atmosphere, 52 g (162.38 mmol) of 2,2′-bis (trifluoromethyl) benzidine (TFMB) and N, N-dimethylacetamide adjusted to have a water content of 500 ppm were added. (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 the mixture was stirred at room temperature for 3 hours. Thereafter, 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 the mixture was stirred at room temperature for 1 hour. . Then, 8.73 g (110.42 mmol) of pyridine and 10.96 g (107.33 mmol) of acetic anhydride were added to the flask, and the mixture was stirred at room temperature for 30 minutes, and then heated to 70 ° C. using an oil bath, and further heated for 5 minutes. After stirring for an hour, a reaction solution was obtained.
The obtained reaction solution was cooled to room temperature, poured into a large amount of methanol in a thread form, 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 polyamideimide resin.
DMAc was added to the obtained polyamide-imide resin so as to have a concentration of 15% by mass to prepare a polyamide-imide varnish. The obtained polyamideimide varnish is applied on a smooth surface of a polyester base material (trade name “A4100”, manufactured by Toyobo Co., Ltd.) using an applicator so that the thickness of the self-standing film is 55 μm, and is applied at 50 ° C. 30 After drying at 140 ° C. for 15 minutes, a free-standing film was obtained. The self-standing film was fixed on a metal frame, and further dried at 300 ° C. for 30 minutes in the air to obtain a polyamideimide film having a thickness of 50 μm.

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

[Comparative Example 2]
A polyamide-imide film was obtained in the same manner as in Example 3, except that the stirring time after heating at 70 ° C. was changed to 1 hour to obtain a polyamide-imide resin.

[Comparative Example 3]
In a 1 L separable flask equipped with a stirring blade under a nitrogen atmosphere, 52 g (162.38 mmol) of 2,2′-bis (trifluoromethyl) benzidine (TFMB) and N, N-dimethylacetamide adjusted to have a water content of 500 ppm were added. 831.46 g of (DMAc) 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 the mixture was 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 the mixture was stirred at room temperature for 30 minutes, and then heated to 70 ° C. using an oil bath. After stirring for an hour, a reaction solution was obtained.
The obtained reaction solution was cooled to room temperature, poured into a large amount of methanol in a thread form, 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 as to have a concentration of 15% by mass to prepare a polyimide varnish. The obtained polyimide varnish is applied on a smooth surface of a polyester substrate (manufactured by Toyobo Co., Ltd., trade name “A4100”) using an applicator so that the thickness of the self-supporting film becomes 55 μm, and is applied at 50 ° C. for 30 minutes. Then, drying was performed at 140 ° C. for 15 minutes to obtain a free-standing film. The self-supporting film was fixed on a metal frame, and further dried at 300 ° C. for 30 minutes in the atmosphere to obtain a polyimide film having a thickness of 50 μm.

[Comparative Example 4]
In a 1 L separable flask equipped with a stirring blade under a nitrogen atmosphere, 52 g (162.38 mmol) of 2,2′-bis (trifluoromethyl) benzidine (TFMB) and N, N-dimethylacetamide adjusted to have a water content of 500 ppm were added. (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 the mixture was 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 the mixture was stirred at room temperature for 30 minutes, and then heated to 70 ° C. using an oil bath. After stirring for an hour, a reaction solution was obtained.
The obtained reaction solution was cooled to room temperature, poured into a large amount of methanol in a thread form, 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 as to have a concentration of 15% by mass to prepare a polyimide varnish. The obtained polyimide varnish is applied on a smooth surface of a polyester substrate (manufactured by Toyobo Co., Ltd., trade name “A4100”) using an applicator so that the thickness of the self-supporting film becomes 55 μm, and is applied at 50 ° C. for 30 minutes. Then, drying was performed at 140 ° C. for 15 minutes to obtain a free-standing film. The self-supporting film was fixed on a metal frame, and further dried at 300 ° C. for 30 minutes in the atmosphere to obtain a polyimide film having a thickness of 50 μm.

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

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

[Comparative Example 7]
A polyamide-imide film was obtained in the same manner as in Example 5, except that the stirring time after heating at 70 ° C. was changed to 30 minutes in Example 5, and a polyamide-imide resin was obtained.

[Comparative Example 8]
A polyamide-imide film was obtained in the same manner as in Example 7, except that the stirring time after heating at 70 ° C. was changed to 30 minutes and a polyamide-imide resin was obtained.

Example 8
In a 1 L separable flask equipped with a stirring blade under a nitrogen gas atmosphere, 45 g (140.5 mmol) of 2,2′-bis (trifluoromethyl) benzidine (TFMB) and N, N-dimethyl having a water content adjusted to 200 ppm were added. 600.9 g of acetamide (DMAc) was added, and TFMB was dissolved in DMAc while 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 the mixture was stirred at room temperature for 2.5 hours. 25.01 g (56.3 mmol) of-(hexafluoroisopropylidene) diphthalic dianhydride (6FDA) was added, and the mixture was 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 the mixture was 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, and the mixture was stirred at room temperature for 30 minutes, and then heated to 70 ° C. using an oil bath. The mixture was stirred for 3 hours to obtain a reaction solution.
After the obtained reaction solution was cooled to room temperature, 647 g of methanol and 180 g of ion-exchanged water were added to obtain a precipitate of polyamideimide. It was immersed 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 polyamideimide resin. Table 1 shows the molar ratio of each component.
DMAc was added to the obtained polyamide-imide resin so as to have a concentration of 15% by mass to prepare a polyamide-imide varnish. The obtained polyamideimide varnish is applied on a smooth surface of a polyester base material (trade name “A4100”, manufactured by Toyobo Co., Ltd.) using an applicator so that the thickness of the self-standing film is 55 μm, and is applied at 50 ° C. 30 After drying at 140 ° C. for 15 minutes, a free-standing film was obtained. The self-standing film was fixed on a metal frame, and further dried at 300 ° C. for 30 minutes in the air to obtain a polyamideimide film having a thickness of 50 μm.

[Example 9]
Under a nitrogen gas atmosphere, in a 1 L separable flask equipped with a stirring blade, 14.2 g (45.8 mmol) of 2,2′-bis (trifluoromethyl) benzidine (TFMB) and N and N adjusted to have a water content of 200 ppm were added. -233.3 g of dimethylacetamide (DMAc) 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 the mixture was stirred at room temperature for 16.5 hours. Thereafter, 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 the mixture was 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, and the mixture was stirred at room temperature for 30 minutes, and then heated to 70 ° C. using an oil bath. The mixture was stirred for 3 hours to obtain a reaction solution.
After the obtained reaction solution was cooled to room temperature, 360 g of methanol and 170 g of ion-exchanged water were added to obtain a polyamideimide precipitate. It was immersed 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 polyamideimide resin. Table 1 shows the molar ratio of each component.
In the same manner as in Example 8, a polyamide-imide film having a thickness of 50 μm was obtained from the polyamide-imide resin obtained in Example 9.

[Example 10]
6.140 g of 4,4 ′-(hexafluoroisopropylidene) diphthalic dianhydride (6FDA) was replaced with 4.283 g of 4,4′-oxydiphthalic dianhydride (OPDA), and 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). In the same manner as in Example 9, a polyamideimide resin was obtained. Table 1 shows the molar ratio of each component.
In the same manner as in Example 8, a polyamide-imide film having a thickness of 50 μm was obtained from the polyamide-imide resin obtained in Example 10.

[Example 11]
Polyamideimide was prepared 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.
In the same manner as in Example 8, a polyamide-imide film having a thickness of 50 μm was obtained from the polyamide-imide resin obtained in Example 11.

  The following Table 1 shows the ratio of each structural unit and the synthesis conditions in the polyamide-imide resin (B) contained in the polyamide-imide varnish obtained in the above example and the resin (B) contained in the varnish obtained in the comparative example. Table 1 also shows the results obtained by measuring the imidation ratio of the polyamide-imide resin (B) and the resin (B) according to the above-described measurement method. In Table 1, the imidation ratio of the polyamide-imide resin (B) and the resin (B) is “imidation ratio B”, the amount of water in the solvent at the start of the step (1) is “w [ppm]”, The heating time in the step (2) is “t [min]”, and the ratio of the molar amount of the dehydrating agent added in the step (2) to the molar amount of the tetracarboxylic dianhydride added in the step (1) is “ Dehydrating agent addition amount ". Here, in the measurement of the imidation ratio B of the polyimide resin B obtained in Comparative Examples 3 and 4, a polyimide resin B was prepared in the same manner as the polyamide imide resin B except that the resin was changed.

  The results obtained by measuring the imidation ratio of the polyamide-imide resin (A) contained in the polyamide-imide film obtained in the above example and the resin (A) contained in the film obtained in the above-mentioned comparative example in accordance with the above-mentioned measurement method are shown in the table. 2 is shown as "Imidation ratio A". Here, in the measurement of the imidation ratio of the polyimide resin A contained in the polyimide films obtained in Comparative Examples 3 and 4, a polyimide resin A was prepared in the same manner as the polyamide imide resin A except that the resin was changed. Further, the films obtained in Examples and Comparative Examples were measured for pencil hardness, yellowness (YI), total light transmittance (Tt), elastic modulus and bending resistance (number of reciprocating bendings) in accordance with the above-mentioned measuring methods. Table 1 shows the obtained results. The proportions of the respective constituent units in the polyamide-imide resin (A) contained in the polyamide-imide film and the resin (A) contained in the film obtained in the above comparative example correspond to the respective polyamide-imides shown in Table 1. It is the same as the ratio of the constituent units in the resin (B) and the resin (B). Further, in Examples 10 and 11, it was confirmed that signals derived from structures different from the repeating unit having an amic acid and the repeating unit having an imide bond overlap. For this reason, 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 (6)

(1) a step of copolymerizing a diamine, a dicarboxylic acid, and a tetracarboxylic dianhydride in a solvent to obtain a polyamide-imide 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 the solution at a temperature of 70 to 120 ° C. Assuming that the amount of water in the solvent at the start of (1) is w (ppm) and the heating time in step (2) is t (min), w and t are represented by the following formulas:

Meet the manufacturing method.   The method according to claim 1, wherein the molar amount of the dehydrating agent added in the step (2) is at least twice the molar amount of the tetracarboxylic dianhydride added in the step (1). The diamine has the formula (3):

[In the formula (3), X is the 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 production method according to claim 1, comprising at least one compound represented by the formula: The dicarboxylic acid has the formula (2):

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

Wherein (2a) and formula (2b), ^{U 1} represents 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— , wherein Ar represents an arylene group having 6 to 20 carbon atoms in which a hydrogen atom may be substituted by a fluorine atom; * Represents a bond)
Wherein B ¹ and B ² each independently represent OH or a halogen atom]
The production method according to claim 1, comprising at least one compound represented by the following formula: The tetracarboxylic dianhydride has the formula (4):

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

[In the formula (4g), W ¹ represents a single bond, -C (CH ₃ ) ₂ -or -C (CF ₃ ) _2- , and * represents a bond]
Represents]
The production method according to claim 1, comprising at least one compound represented by the following formula:   The method according to claim 1, wherein the polyamideimide resin has an imidization ratio of 60% or more.