JP6554599B1 - Optical film - Google Patents

Abstract

An optical film having excellent bending resistance and excellent optical property stability under high temperature and high humidity is provided. An optical film of the present invention comprises a polyamide-imide resin, and has the formula (1) ΔHz <0.5 (1) [where, ΔHz represents Hza-Hzb, and Hza is at room temperature. The haze (%) of the optical film after a mandrel test (conforming to JIS K 5600-5-1: 1999) is bent once at a bending radius of 1 mm and returned to a flat shape, and Hzb is the haze of the optical film before the mandrel test. (%) Is satisfied. [Selection figure] None

Description

  The present invention relates to an optical film used as a material for a flexible display.

  Image display devices such as liquid crystal display devices and organic EL display devices are widely used in various applications such as mobile phones and smart watches. Glass has been used as the front plate of such an image display device. However, since glass is very rigid and easily broken, it is difficult to use it as a front plate material for a flexible display. As one of materials to replace glass, there is a polyamideimide resin, and a polyamideimide film having high heat resistance and the like using the polyamideimide resin has been studied (for example, Patent Document 1).

Special table 2014-528490 gazette

  However, according to the study of the present inventor, when using such a polyamideimide film (optical film) as a flexible display material, the case where the bending resistance and the stability of the optical characteristics under high temperature and high humidity are not sufficient. I found out that

  Accordingly, an object of the present invention is to provide an optical film having excellent bending resistance and excellent optical properties under high temperature and high humidity.

［式（Ｉ）中、Ｒ^１及びＲ^２はそれぞれ独立に、ヒドロキシル基、メトキシ基、エトキシ基、ｎ−プロポキシ基、ｎ−ブトキシ基又は塩素原子を表し、Ｒ^３〜Ｒ^６はそれぞれ独立に、水素原子、炭素数１〜６のアルキル基又は炭素数６〜１２のアリール基を表し、Ｒ^３〜Ｒ^６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い］
で表される化合物由来の構成単位を含み、
式（２）
０＜Ｒ_Ｓｉ≦３２＋２／３×Ｒ_（Ｉ） （２）
［式（２）中、Ｒ_Ｓｉは光学フィルムの質量に対するシリカ粒子の含有量（質量％）を表し、Ｒ_（Ｉ）はポリアミドイミド樹脂を構成する全構成単位の総モル数に対する式（Ｉ）で表される化合物由来の構成単位の含有量（モル％）を表す］
の関係を満たす、［２］又は［３］に記載の光学フィルム。
［５］前記式（２）は、５≦Ｒ_Ｓｉ≦５０である、［４］に記載の光学フィルム。
［６］前記ポリアミドイミド樹脂を構成するテトラカルボン酸化合物由来の構成単位は、式（ＩＩ）

［式（ＩＩ）中、Ｒ^７〜Ｒ^１４はそれぞれ独立に、水素原子、炭素数１〜６のアルキル基又は炭素数６〜１２のアリール基を表し、Ｒ^７〜Ｒ^１４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い］
で表される化合物由来の構成単位を含み、及び前記ポリアミドイミド樹脂を構成するジアミン化合物由来の構成単位は、式（ＩＩＩ）

［式（ＩＩＩ）中、Ｒ^１５〜Ｒ^２２は、それぞれ独立に、水素原子、炭素数１〜６のアルキル基又は炭素数６〜１２のアリール基を表し、Ｒ^１５〜Ｒ^２２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い］
で表される化合物由来の構成単位を含む、［２］〜［５］のいずれかに記載の光学フィルム。
［７］ポリアミドイミド樹脂を構成するジカルボン酸化合物由来の構成単位は、式（ＩＶ）

［式（ＩＶ）中、Ｒ^２３及びＲ^２４は、それぞれ独立に、ヒドロキシル基、メトキシ基、エトキシ基、ｎ−プロポキシ基、ｎ−ブトキシ基又は塩素原子を表し、Ｒ^２５〜Ｒ^３２は、それぞれ独立に、水素原子、炭素数１〜６のアルキル基又は炭素数６〜１２のアリール基を表し、Ｒ^２５〜Ｒ^３２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−、−ＣＨ_２−、−ＣＨ_２−ＣＨ_２−、−ＣＨ（ＣＨ_３）−、−Ｃ（ＣＨ_３）_２−、−Ｃ（ＣＦ_３）_２−、−ＳＯ_２−、−Ｓ−、−ＣＯ−又は−ＮＲ^３３−を表し、Ｒ^３３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の整数を表す］
で表される化合物由来の構成単位を含む、［２］〜［６］のいずれかに記載の光学フィルム。 As a result of intensive studies to solve the above problems, the present inventors have completed the present invention. That is, the following preferred embodiments are included in the present invention.
[1] An optical film comprising a polyamideimide resin, wherein
Formula (1)
ΔHz <0.5 (1)
[In the formula (1), ΔHz represents Hz _a -Hz _b , and Hz _a is bent at a bending radius of 1 mm at room temperature and bent once to return to a flat shape (according to JIS K 5600-5-1: 1999). Represents the haze (%) of the optical film and the Hz _b represents the haze (%) of the optical film before the mandrel test]
Optical film that satisfies the relationship of
[2] The polyamideimide resin is a resin including a structural unit derived from a dicarboxylic acid compound, a structural unit derived from a tetracarboxylic acid compound, and a structural unit derived from a diamine compound, and further has an average primary particle diameter of 100 nm or less. The optical film according to [1], comprising:
[3] The optical film according to [2], wherein the average primary particle diameter of the silica particles is 80 nm or less.
[4] The constituent unit derived from the dicarboxylic acid compound constituting the polyamideimide resin is represented by the formula (I)

[In formula (I), R ¹ and R ² each independently represent a hydroxyl group, a methoxy group, an ethoxy group, an n-propoxy group, an n-butoxy group or a chlorine atom, and R ^{3 to} R ⁶ each independently represent Represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an aryl group having 6 to 12 carbon atoms, and the hydrogen atoms contained in R ^{3 to} R ⁶ may be each independently substituted with a halogen atom.
Comprising a structural unit derived from a compound represented by
Formula (2)
0 <R _Si ≦ 32 + 2/3 × R _(I) (2)
[In formula (2), R _Si represents the content (% by mass) of silica particles with respect to the mass of the optical film, and R _(I) represents the formula (I) with respect to the total number of moles of all constituent units constituting the polyamideimide resin Represents the content (mol%) of the constituent unit derived from the compound represented by
The optical film as described in [2] or [3] which satisfy | fills the relationship of.
[5] The optical film according to [4], wherein the formula (2) satisfies 5 ≦ R _Si ≦ 50.
[6] The constituent unit derived from the tetracarboxylic acid compound constituting the polyamideimide resin is represented by the formula (II)

[In Formula ^(II), the R 7 ^{to R 14} are each independently a hydrogen atom, an alkyl group or an aryl group having 6 to 12 carbon atoms having 1 to 6 carbon ^atoms, hydrogen atoms contained in R 7 ^{to R 14} Each may be independently substituted with a halogen atom]
And a constituent unit derived from a diamine compound constituting the polyamideimide resin and having a constituent unit derived from a compound represented by formula (III):

Wherein ^{(III), R} 15 ~R ²² independently represent a hydrogen atom, an alkyl group or an aryl group having 6 to 12 carbon atoms having 1 to 6 carbon ^atoms, hydrogen contained in R 15 ^{to R 22} Each atom may be independently substituted with a halogen atom]
The optical film in any one of [2]-[5] containing the structural unit derived from the compound represented by these.
[7] The structural unit derived from the dicarboxylic acid compound constituting the polyamideimide resin has the formula (IV)

[In Formula (IV), R ²³ and R ²⁴ each independently represent a hydroxyl group, a methoxy group, an ethoxy group, an n-propoxy group, an n-butoxy group, or a chlorine atom, and R ^{25 to} R ³² each represent Independently, it represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an aryl group having 6 to 12 carbon atoms, and the hydrogen atoms contained in R ^{25 to} R ³² may be each independently substituted by a halogen atom well, a is _{independently, -O -, - CH 2 -} , - CH 2 -CH 2 -, - CH (CH 3) -, - C (CH 3) 2 -, - C (CF 3) 2 _{-, - SO 2 -, -} S -, - CO- or ^{-NR 33} - ^{represents, R 33} represents a hydrocarbon group having 1 to 12 carbon atoms which may be substituted with a halogen atom, m is 1 Represents an integer of 4]
The optical film in any one of [2]-[6] containing the structural unit derived from the compound represented by these.

  The optical film of the present invention has excellent bending resistance and excellent stability of optical characteristics under high temperature and high humidity.

  The optical film of the present invention comprises a polyamideimide resin.

<Polyamide imide resin>
In the present specification, a polyamideimide resin refers to a polymer containing both a repeating structural unit containing an imide group and a repeating structural unit containing an amide group. The polyamideimide resin is preferably a resin in which a dicarboxylic acid compound, a tetracarboxylic acid compound, and, if necessary, a carboxylic acid compound containing a tricarboxylic acid compound, and a diamine compound are copolymerized. Therefore, the polyamideimide resin of the present invention comprises a structural unit derived from a dicarboxylic acid compound, a structural unit derived from a tetracarboxylic acid compound, and, if necessary, a structural unit derived from a carboxylic acid compound and a diamine. And a structural unit derived from a compound. In the present specification, “a structural unit derived from a compound” may be simply referred to as “unit”. For example, a dicarboxylic acid “compound-derived structural unit” is referred to as a dicarboxylic acid “unit”, a tetracarboxylic acid “compound-derived structural unit” is referred to as a tetracarboxylic acid “unit”, and a diamine “compound-derived structural unit” is referred to as a diamine. Sometimes referred to as “unit”.

［式（Ｉ）中、Ｒ^１及びＲ^２はそれぞれ独立に、ヒドロキシル基、メトキシ基、エトキシ基、ｎ−プロポキシ基、ｎ−ブトキシ基又は塩素原子を表し、Ｒ^３〜Ｒ^６はそれぞれ独立に、水素原子、炭素数１〜６のアルキル基又は炭素数６〜１２のアリール基を表し、Ｒ^３〜Ｒ^６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い］
で表される化合物由来の構成単位（ジカルボン酸化合物（Ｉ）由来の構成単位と称する場合がある）を含むことが好ましい。 The structural unit derived from the dicarboxylic acid compound constituting the polyamideimide resin has the formula (I)

[In Formula (I), R ¹ and R ² each independently represent a hydroxyl group, a methoxy group, an ethoxy group, an n-propoxy group, an n-butoxy group or a chlorine atom, and R ^{3 to} R ⁶ each independently represent , A hydrogen atom, an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 12 carbon atoms, and the hydrogen atoms contained in R ^{3 to} R ⁶ may be each independently substituted with a halogen atom]
It is preferable to include a constituent unit derived from the compound represented by (sometimes referred to as a constituent unit derived from a dicarboxylic acid compound (I)).

［式（ＩＩ）中、Ｒ^７〜Ｒ^１４はそれぞれ独立に、水素原子、炭素数１〜６のアルキル基又は炭素数６〜１２のアリール基を表し、Ｒ^７〜Ｒ^１４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い］
で表される化合物由来の構成単位（テトラカルボン酸化合物（ＩＩ）由来の構成単位と称する場合がある）を含むことが好ましく、ポリアミドイミド樹脂を構成するジアミン化合物由来の構成単位は、式（ＩＩＩ）

［式（ＩＩＩ）中、Ｒ^１５〜Ｒ^２２は、それぞれ独立に、水素原子、炭素数１〜６のアルキル基又は炭素数６〜１２のアリール基を表し、Ｒ^１５〜Ｒ^２２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い］
で表される化合物由来の構成単位（ジアミン化合物（ＩＩＩ）由来の構成単位と称する場合がある）を含むことが好ましい。ここで、ポリアミドイミド樹脂において、ジカルボン酸化合物（Ｉ）由来の構成単位は、ジカルボン酸化合物（Ｉ）とジアミン化合物との反応（重縮合）により形成されたアミド基を介して、ジアミン化合物由来の構成単位と結合し得る。テトラカルボン酸化合物（ＩＩ）由来の構成単位は、テトラカルボン酸化合物（ＩＩ）とジアミン化合物との反応（重縮合）により形成されたイミド基を介して、ジアミン化合物由来の構成単位と結合し得る。ジアミン化合物（ＩＩＩ）由来の構成単位は、ジアミン化合物（ＩＩＩ）とジカルボン酸、トリカルボン酸又はテトラカルボン酸との反応（重縮合）により形成されたアミド基又はイミド基を介して、ジカルボン酸化合物由来の構成単位、トリカルボン酸化合物由来の構成単位又はテトラカルボン酸化合物由来の構成単位と結合し得る。 The structural unit derived from the tetracarboxylic acid compound constituting the polyamideimide resin is represented by the formula (II)

[In Formula ^(II), the R 7 ^{to R 14} are each independently a hydrogen atom, an alkyl group or an aryl group having 6 to 12 carbon atoms having 1 to 6 carbon ^atoms, hydrogen atoms contained in R 7 ^{to R 14} Each may be independently substituted with a halogen atom]
It is preferable to include a constituent unit derived from a compound represented by (sometimes referred to as a constituent unit derived from tetracarboxylic acid compound (II)), and a constituent unit derived from a diamine compound constituting the polyamideimide resin is represented by the formula (III )

Wherein ^{(III), R} 15 ~R ²² independently represent a hydrogen atom, an alkyl group or an aryl group having 6 to 12 carbon atoms having 1 to 6 carbon ^atoms, hydrogen contained in R 15 ^{to R 22} Each atom may be independently substituted with a halogen atom]
It is preferable that the structural unit derived from the compound represented by (it may be called the structural unit derived from diamine compound (III)) is included. Here, in the polyamideimide resin, the structural unit derived from the dicarboxylic acid compound (I) is derived from the diamine compound via the amide group formed by the reaction (polycondensation) between the dicarboxylic acid compound (I) and the diamine compound. It can be combined with a building block. The structural unit derived from the tetracarboxylic acid compound (II) can be bonded to the structural unit derived from the diamine compound via an imide group formed by the reaction (polycondensation) of the tetracarboxylic acid compound (II) and the diamine compound. . The structural unit derived from the diamine compound (III) is derived from the dicarboxylic acid compound via the amide group or imide group formed by the reaction (polycondensation) of the diamine compound (III) with dicarboxylic acid, tricarboxylic acid or tetracarboxylic acid. And a structural unit derived from a tricarboxylic acid compound or a structural unit derived from a tetracarboxylic acid compound.

  A dicarboxylic acid unit (preferably, a constituent unit derived from a dicarboxylic acid compound (I)), a tetracarboxylic acid unit (preferably, a constituent unit derived from a tetracarboxylic acid compound (II)) and a diamine unit (preferably a constituent unit of the polyamideimide resin) Is a structural unit derived from the diamine compound (III)), each of which may be contained in one kind or two or more kinds.

In formula (I), R ¹ and R ² are each independently a hydroxyl group (—OH), a methoxy group (—OMe), an ethoxy group (—OEt), an n-propoxy group (—OPr), or an n-butoxy group. (—OBu) or a chlorine atom (—Cl), preferably a chlorine atom (—Cl).

In the formula (I), R ³ , R ⁴ , R ⁵ and R ⁶ each independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 12 carbon atoms. Examples of the alkyl group having 1 to 6 carbon atoms include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, sec-butyl group, tert-butyl group, n-pentyl group, 2-methyl- Examples thereof include a butyl group, a 3-methylbutyl group, a 2-ethyl-propyl group, and an n-hexyl group.

As a C6-C12 aryl group, a phenyl group, a tolyl group, xylyl group, a naphthyl group, a biphenyl group etc. are mentioned, for example. The hydrogen atoms contained in R ^{3 to} R ⁶ may be each independently substituted with a halogen atom, and examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom and an iodine atom. Moreover, as a C6-C12 aryl group substituted by the halogen atom, the chlorophenyl group, the dichlorophenyl group, the bromophenyl group, the dibromophenyl group, the chlorobromophenyl group, the chlorobiphenyl group, the dichlorobiphenyl group, the bromophenyl is mentioned, for example Group, dibromophenyl group, chloronaphthyl group, dichloronaphthyl group, bromonaphthyl group, dibromonaphthyl group and the like.

Among these, from the viewpoint of the bending resistance of the optical film, R ^{3 to} R ⁶ are preferably each independently a hydrogen atom, a methyl group, a fluoro group, a chloro group or a trifluoromethyl group, particularly a hydrogen atom Is preferred. In the present invention, the bending resistance (bending resistance) indicates a characteristic in which scratches, cracks, white turbidity, and the like hardly occur in the optical film when the optical film is continuously bent and returned.

で表される化合物由来の構成単位（ジカルボン酸化合物（Ｉ’）由来の構成単位と称する場合がある）である。ポリアミドイミド樹脂がジカルボン酸化合物（Ｉ’）由来の構成単位を含むと、光学フィルムの機械的強度、例えば弾性率や耐屈曲性を向上しやすい。 In a further preferred embodiment of the present invention, the constituent unit derived from the compound represented by formula (I) is a compound of formula (I ′)

A structural unit derived from a compound represented by the formula (sometimes referred to as a structural unit derived from a dicarboxylic acid compound (I ′)). When the polyamideimide resin contains a structural unit derived from the dicarboxylic acid compound (I ′), the mechanical strength of the optical film, for example, the elastic modulus and the bending resistance can be easily improved.

In the formula (II), R ⁷ , R ⁸ , R ⁹ , R ¹⁰ , R ¹¹ , R ¹² , R ¹³ and R ¹⁴ are each independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or 6 to 6 carbon atoms. 12 represents an aryl group. Examples of the alkyl group having 1 to ⁶ carbon atoms include those exemplified as the alkyl group having 1 to ⁶ carbon atoms of R ^{3 to} R ⁶ . Examples of the aryl group having 6 to 12 carbon atoms include those exemplified as the aryl group having 6 to 12 carbon atoms of R ^{3 to} R ⁶ . Hydrogen atoms contained in R ⁷ to R ¹⁴ each independently may be substituted with a halogen atom, the halogen atom, fluorine atom, chlorine atom, bromine atom, and an iodine atom. The aryl group having 6 to 12 carbon atoms which is substituted by halogen atoms, examples are mentioned as the aryl group having 6 to 12 carbon atoms which is substituted with a halogen atom R ³ to R ^6.

Among these, from the viewpoint of easily improving the bending resistance and transparency of the optical film, each of R ^{7 to} R ¹⁴ independently represents a hydrogen atom, a methyl group, a fluoro group, a chloro group or a trifluoromethyl group. R ⁷ , R ⁸ , R ⁹ , R ¹² , R ¹³ and R ¹⁴ are each a hydrogen atom, R ¹⁰ and R ^{11 each} is a hydrogen atom, a methyl group, a fluoro group, a chloro group or a trifluoromethyl group In particular, R ¹⁰ and R ¹¹ are preferably a methyl group or a trifluoromethyl group.

で表される化合物由来の構成単位（テトラカルボン酸化合物（ＩＩ’）由来の構成単位と称する場合がある）である。ポリアミドイミド樹脂がテトラカルボン酸化合物（ＩＩ’）由来の構成単位を含むと、光学フィルムの耐屈曲性及び透明性（例えば、ヘイズ、全光線透過率）を向上できる。さらに、フッ素元素を含有する骨格によりポリアミドイミド樹脂の溶媒への溶解性を向上し、ポリアミドイミドワニスの粘度を低く抑制することができ、また光学フィルムの製造が容易となる。 In a preferred embodiment of the present invention, the structural unit derived from the compound represented by formula (II) is represented by formula (II ′).

A structural unit derived from a compound represented by the formula (sometimes referred to as a structural unit derived from a tetracarboxylic acid compound (II ′)). When the polyamideimide resin contains a structural unit derived from the tetracarboxylic acid compound (II ′), the flex resistance and transparency (for example, haze, total light transmittance) of the optical film can be improved. Furthermore, the solubility of the polyamideimide resin in the solvent can be improved by the skeleton containing a fluorine element, the viscosity of the polyamideimide varnish can be suppressed to a low level, and the production of the optical film becomes easy.

In the formula (III), R ¹⁵ , R ¹⁶ , R ¹⁷ , R ¹⁸ , R ¹⁹ , R ²⁰ , R ²¹ , and R ²² are each independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or a carbon number 6 to 12 aryl groups are represented. Examples of the alkyl group having 1 to ⁶ carbon atoms include those exemplified as the alkyl group having 1 to ⁶ carbon atoms of R ^{3 to} R ⁶ . The aryl group having 6 to 12 carbon ^atoms, examples are mentioned as the aryl group having 6 to 12 carbon atoms R 3 to R ^6. Hydrogen atoms contained in R ¹⁵ to R ²² each independently may be substituted with a halogen atom, the halogen atom, such as fluorine atom, chlorine atom, bromine atom, and an iodine atom. The aryl group having 6 to 12 carbon atoms which is substituted by halogen atoms, examples are mentioned as the aryl group having 6 to 12 carbon atoms which is substituted with a halogen atom R ³ to R ^6.

Among these, from the viewpoint of easily improving the transparency of the optical film, R ^{15 to} R ²² are preferably each independently a hydrogen atom, a methyl group, a fluoro group, a chloro group or a trifluoromethyl group, and more preferably preferably ^{R 15, R 17, R 18} , R 19, R 20, and ^{R 22} is a hydrogen ^{atom, R 16} and ^{R 21} is a hydrogen atom, a methyl group, fluoro group, chloro group or a trifluoromethyl group, especially R ¹⁶ and R ²¹ are preferably a methyl group or a trifluoromethyl group.

で表される化合物由来の構成単位（ジアミン化合物（ＩＩＩ’）由来の構成単位と称する場合がある）である。ポリアミドイミド樹脂がジアミン化合物（ＩＩＩ’）由来の構成単位を含むと、光学フィルムの機械的強度（例えば、弾性率、耐屈曲性）及び透明性を向上できる。さらに、フッ素元素を含有する骨格によりポリアミドイミド樹脂の溶媒への溶解性を向上し、ポリアミドイミドワニスの粘度を低く抑制することができ、また光学フィルムの製造が容易となる。 In a preferred embodiment of the present invention, the structural unit derived from the compound represented by formula (III) is represented by formula (III ′).

Or a constituent unit derived from the compound represented by (sometimes referred to as a constituent unit derived from a diamine compound (III ′)). When the polyamideimide resin contains a structural unit derived from the diamine compound (III ′), the mechanical strength (for example, elastic modulus and flex resistance) and transparency of the optical film can be improved. Furthermore, the solubility of the polyamideimide resin in the solvent can be improved by the skeleton containing the fluorine element, the viscosity of the polyamideimide varnish can be suppressed low, and the production of the optical film is facilitated.

［式（ＩＶ）中、Ｒ^２３及びＲ^２４は、それぞれ独立に、ヒドロキシル基、メトキシ基、エトキシ基、ｎ−プロポキシ基、ｎ−ブトキシ基又は塩素原子を表し、Ｒ^２５〜Ｒ^３２は、それぞれ独立に、水素原子、炭素数１〜６のアルキル基又は炭素数６〜１２のアリール基を表し、Ｒ^２５〜Ｒ^３２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−、−ＣＨ_２−、−ＣＨ_２−ＣＨ_２−、−ＣＨ（ＣＨ_３）−、−Ｃ（ＣＨ_３）_２−、−Ｃ（ＣＦ_３）_２−、−ＳＯ_２、−Ｓ−、−ＣＯ−又は−ＮＲ^３３−を表し、Ｒ^３３は水素原子、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の整数を表す］
で表される化合物由来の構成単位（ジカルボン酸化合物（ＩＶ）由来の構成単位と称する場合がある）を含むことが好ましい。 From the viewpoint of easily improving the flex resistance and transparency of the optical film, the polyamideimide resin contained in the optical film of the present invention has two or more aromatic hydrocarbon rings as single bonds and aromatic groups as dicarboxylic acid units. It is preferable that the structural unit derived from the aromatic dicarboxylic acid compound connected by the bivalent group except is included. Examples of the aromatic hydrocarbon ring include a monocyclic hydrocarbon ring such as a benzene ring; a fused bicyclic hydrocarbon ring such as a naphthalene; and a polycyclic hydrocarbon ring such as a ring-aggregated hydrocarbon ring such as a biphenyl And preferably a benzene ring. Specifically, the formula (IV)

[In Formula (IV), R ²³ and R ²⁴ each independently represent a hydroxyl group, a methoxy group, an ethoxy group, an n-propoxy group, an n-butoxy group, or a chlorine atom, and R ^{25 to} R ³² each represent Independently, it represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an aryl group having 6 to 12 carbon atoms, and the hydrogen atoms contained in R ^{25 to} R ³² may be each independently substituted by a halogen atom well, a is _{independently, -O -, - CH 2 -} , - CH 2 -CH 2 -, - CH (CH 3) -, - C (CH 3) 2 -, - C (CF 3) 2 —, —SO ₂ , —S—, —CO— or —NR ³³ —, wherein R ³³ represents a hydrogen atom or a hydrocarbon group having 1 to 12 carbon atoms which may be substituted with a halogen atom; Represents an integer of 1 to 4]
It is preferable to include a constituent unit derived from the compound represented by (sometimes referred to as a constituent unit derived from a dicarboxylic acid compound (IV)).

In formula (IV), A is a drying temperature tends to lower temperatures, and from easy in view of the optical film is obtained having good flexibility, _{independently, -O -, - CH 2 -} , - CH 2 - _{CH 2 -, - CH (CH} 3) -, - C (CH 3) 2 -, - C (CF 3) 2 -, - SO 2 -, - S -, - CO- or ^{-NR 33} - represents, From the viewpoint of easily obtaining an optical film excellent in bending resistance, -O-, -CH _2- , -C (CH ₃ ) _2- , -C (CF ₃ ) _2- , -SO ₂ or -S is preferable. -, more preferably _{-O -, - CH 2 -,} - C (CH 3) 2 - or -SO ₂ - represents, more preferably a -O-. R ²³ and R ²⁴ each independently represent a hydroxyl group, a methoxy group, an ethoxy group, an n-propoxy group, an n-butoxy group or a chlorine atom, and R ²⁵ , R ²⁶ , R ²⁷ , R ²⁸ , R ²⁹ , R ^{30, R 31,} and ^{R 32} each independently represent a hydrogen atom, an alkyl group or an aryl group having 6 to 12 carbon atoms having 1 to 6 carbon atoms. The alkyl group having 1 to 6 carbon ^atoms, examples are mentioned as the alkyl group having 1 to 6 carbon atoms R 3 to R ^6. The aryl group having 6 to 12 carbon ^atoms, examples are mentioned as the aryl group having 6 to 12 carbon atoms R 3 to R ^6. The hydrogen atoms contained in R ^{25 to} R ³² may be each independently substituted with a halogen atom, and examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom and an iodine atom. The aryl group having 6 to 12 carbon atoms which is substituted by halogen atoms, examples are mentioned as the aryl group having 6 to 12 carbon atoms which is substituted with a halogen atom R ³ to R ^6. R ³³ represents a hydrocarbon group having 1 to 12 carbon atoms which may be substituted with a halogen atom. Examples of the hydrocarbon group having 1 to 12 carbon atoms include those exemplified as the alkyl group having 1 to ⁶ carbon atoms of R ^{3 to} R ⁶ and those exemplified as the aryl group having 6 to 12 carbon atoms.

  In the formula (IV), m represents an integer of 1 to 4, and when m is within this range, an optical film having good bending resistance and elastic modulus is easily obtained. In the formula (IV), m is preferably an integer of 1 to 3, more preferably 1 or 2, and more preferably 1. When m is in this range, the elastic modulus is more easily improved.

Among these, from the viewpoint of easily increasing the flex resistance of the optical film, R ^{25 to} R ³² are preferably a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and a hydrogen atom or an alkyl having 1 to 3 carbon atoms. It is more preferably a group, and further preferably a hydrogen atom.

で表される化合物由来の構成単位（ジカルボン酸化合物（ＩＶ’）由来の構成単位と称する場合がある）である。ポリアミドイミド樹脂がジカルボン酸化合物（ＩＶ’）由来の構成単位を含むと、光学フィルムの耐屈曲性及び透明性を向上できる。さらに、フッ素元素を含有する骨格によりポリアミドイミド樹脂の溶媒への溶解性を向上し、ポリアミドイミドワニスの粘度を低く抑制することができ、また光学フィルムの製造が容易となる。 In a preferred embodiment of the present invention, the structural unit derived from the compound represented by formula (IV) is represented by formula (IV ′).

A structural unit derived from a compound represented by the formula (sometimes referred to as a structural unit derived from a dicarboxylic acid compound (IV ′)). When the polyamideimide resin contains a structural unit derived from the dicarboxylic acid compound (IV ′), the flexibility and transparency of the optical film can be improved. Furthermore, the solubility of the polyamideimide resin in the solvent can be improved by the skeleton containing a fluorine element, the viscosity of the polyamideimide varnish can be suppressed to a low level, and the production of the optical film becomes easy.

  In a preferred embodiment of the present invention, the polyamideimide resin of the present invention is a resin containing a structural unit derived from a dicarboxylic acid compound, a structural unit derived from a tetracarboxylic acid compound, and a structural unit derived from a diamine compound. Further, in a more preferred aspect of the present invention, the polyamideimide resin of the present invention comprises a structural unit derived from a dicarboxylic acid compound (I), a structural unit derived from a tetracarboxylic acid compound (II), and a structure derived from a diamine compound (III) It is resin which consists of a unit and the structural unit derived from dicarboxylic acid compound (IV). In a further preferred aspect of the present invention, the polyamideimide resin of the present invention comprises a structural unit derived from a dicarboxylic acid compound (I ′), a structural unit derived from a tetracarboxylic acid compound (II ′), and a diamine compound (III ′) It is resin which consists of a structural unit and a structural unit derived from dicarboxylic acid compound (IV '). An optical film containing a polyamide-imide resin having such a structural unit is advantageous in terms of bending resistance and transparency (particularly, maintenance of transparency in a high temperature / high humidity environment).

  In one embodiment of the present invention, the polyamideimide resin is a structural unit derived from the dicarboxylic acid compound (I) and a structural unit derived from the dicarboxylic acid compound (IV), as long as various physical properties of the optical film are not impaired. Other structural units other than the structural unit derived from the tetracarboxylic acid compound (II) and the structural unit derived from the diamine compound (III) may be included.

  As another structural unit, for example, a structural unit derived from a dicarboxylic acid compound (I) and a structural unit derived from another dicarboxylic acid compound other than a structural unit derived from a dicarboxylic acid compound (IV), a tetracarboxylic acid compound (II) Other structural units derived from tetracarboxylic acid compounds other than the structural units, structural units derived from tricarboxylic acid compounds, structural units derived from other diamine compounds other than the structural units derived from diamine compound (III), and the like can be mentioned. The dicarboxylic acid compound represents a dicarboxylic acid or a dicarboxylic acid derivative (for example, an acid chloride or acid anhydride of a dicarboxylic acid), and the tricarboxylic acid compound represents a tricarboxylic acid or a tricarboxylic acid derivative (for example, an acid chloride or acid of a tricarboxylic acid). The tetracarboxylic acid compound represents a tetracarboxylic acid or a tetracarboxylic acid derivative (for example, an acid chloride or acid anhydride of tetracarboxylic acid).

で表される化合物由来の構成単位（ジカルボン酸化合物（Ｖ）由来の構成単位と称する場合がある）が挙げられる。ジカルボン酸単位として、ジカルボン酸化合物（Ｖ）由来の構成単位が１種類又は２種類以上含まれていてもよく、２種類以上含まれる場合、それぞれのジカルボン酸化合物（Ｖ）由来の構成単位においてＺの種類が異なる。 Other dicarboxylic acid units include, for example, formula (V)

And a structural unit derived from a compound represented by the formula (sometimes referred to as a structural unit derived from a dicarboxylic acid compound (V)). As the dicarboxylic acid unit, one type or two or more types of structural units derived from the dicarboxylic acid compound (V) may be included, and in the case where two or more types of structural units are included, Z in each structural unit derived from the dicarboxylic acid compound (V). The type of is different.

In the formula (V), Z is represented by the formula (20), the formula (21), the formula (22), the formula (23), the formula (24), the formula (25), the formula (27) and the formula (29) Of the bonding hands of the group to be represented, two non-adjacent groups are replaced with hydrogen atoms or a divalent chain hydrocarbon group having 6 or less carbon atoms. R ³⁴ and R ³⁵ are each independently a hydroxyl group (—OH), a methoxy group (—OMe), an ethoxy group (—OEt), an n-propoxy group (—OPr), or an n-butoxy group (—OBu). Or it is a chlorine atom (-Cl), and it is preferable that it is a chlorine atom (-Cl).

Specific examples of the dicarboxylic acid compound constituting the dicarboxylic acid unit include, for example, 4,4'-oxybisbenzoic acid, terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, 4,4'-biphenyldicarboxylic acid, 3,3'-biphenyl Aromatic compounds such as dicarboxylic acids, compounds in which two benzoic acids are linked by a single bond, —CH ₂ —, —C (CH ₃ ) ₂ —, —C (CF ₃ ) ₂ —, —SO ₂ — or a phenylene group Dicarboxylic acids and their derivatives (for example, acid chlorides, acid anhydrides); aliphatic dicarboxylic acids such as chain hydrocarbon dicarboxylic acid compounds having 8 or less carbon atoms and their derivatives (for example, acid chlorides, ester compounds), etc. Can be mentioned. These dicarboxylic acid compounds can be used alone or in combination of two or more. Among these, in order to achieve both the elastic modulus and the bending resistance of the optical film, it is preferable to use the compound represented by the formula (I) and the compound represented by the formula (IV) in combination. As a specific example, the combined use of 4,4′-oxybis (benzoyl chloride) and terephthaloyl chloride is preferable.

で表される化合物由来の構成単位（テトラカルボン酸化合物（ＶＩ）由来の構成単位と称する場合がある）、及び式（ＶＩＩ）

で表される化合物由来の構成単位（テトラカルボン酸化合物（ＶＩＩ）由来の構成単位と称する場合がある）が挙げられる。ここで、本発明のポリアミドイミド樹脂において、式（ＶＩ）で表されるテトラカルボン酸化合物由来の構成単位は、ジアミン化合物由来の構成単位と、Ｙの両側に形成されたイミド基を介して結合し得る。また、式（ＶＩＩ）で表されるテトラカルボン酸化合物由来の構成単位は、ジアミン化合物由来の構成単位と、Ｙ^１の一方の側に形成されたイミド基及びＹ^１のもう一方の側に形成されたアミド基を介して結合し得る。テトラカルボン酸単位として、テトラカルボン酸化合物（ＶＩ）由来の構成単位及びテトラカルボン酸化合物（ＶＩＩ）由来の構成単位がそれぞれ、１種類又は２種類以上含まれていてもよい。テトラカルボン酸化合物（ＶＩ）由来の構成単位及びテトラカルボン酸化合物（ＶＩＩ）由来の構成単位がそれぞれ２種類以上含まれる場合、２種類以上のテトラカルボン酸化合物（ＶＩ）由来の構成単位においてＹの種類が異なり、２種類以上のテトラカルボン酸化合物（ＶＩＩ）由来の構成単位においてＹ^１の種類が異なる。 Other tetracarboxylic acid units include, for example, formula (VI)

Or a structural unit derived from a compound represented by (sometimes referred to as a structural unit derived from a tetracarboxylic acid compound (VI)), and a formula (VII)

And a structural unit derived from a compound represented by the formula (sometimes referred to as a structural unit derived from a tetracarboxylic acid compound (VII)). Here, in the polyamideimide resin of the present invention, the structural unit derived from the tetracarboxylic acid compound represented by the formula (VI) is bonded to the structural unit derived from the diamine compound via the imide groups formed on both sides of Y. Can do. The structural unit derived from the tetracarboxylic acid compound represented by the formula (VII) is formed from the structural unit derived from the diamine compound, the imide group formed on one side of Y ¹ , and the other side of Y ^1. It can be linked through a modified amide group. As the tetracarboxylic acid unit, one or more types of structural units derived from the tetracarboxylic acid compound (VI) and structural units derived from the tetracarboxylic acid compound (VII) may be contained, respectively. When two or more structural units derived from the tetracarboxylic acid compound (VI) and two or more structural units derived from the tetracarboxylic acid compound (VII) are included, Y in the structural unit derived from two or more types of the tetracarboxylic acid compound (VI). The types are different, and the type of Y ¹ is different in structural units derived from two or more types of tetracarboxylic acid compounds (VII).

In formula (VI), Y is a tetravalent organic group, preferably a tetravalent organic group having 4 to 40 carbon atoms. The organic group is an organic group in which a hydrogen atom in the organic group may be substituted with a hydrocarbon group or a hydrocarbon group substituted with a halogen atom, in which case the hydrocarbon group and the fluorine-substituted hydrocarbon The number of carbon atoms in the group is preferably 1-8. Y represents a group represented by formula (20), formula (21), formula (23), formula (24), formula (25), formula (27), formula (28), formula (29); A group in which a hydrogen atom in the group represented by the formula is substituted with a methyl group, a fluoro group, a chloro group or a trifluoromethyl group; or a tetravalent chain hydrocarbon group having 6 or less carbon atoms. In Formula (VII), Y ¹ is a tetravalent organic group, and preferably an organic group in which a hydrogen atom in the organic group may be substituted with a hydrocarbon group or a hydrocarbon group substituted with a halogen atom. (20), (21), (23), (24), (25), (26), (27), (28) or (29). Groups in which the hydrogen atom in the groups represented by those formulas is substituted with a methyl group, a fluoro group, a chloro group or a trifluoromethyl group; or a tetracyclic hydrocarbon group having 6 or less carbon atoms Indicates. From the viewpoint of easily reducing the degree of yellowness of the optical film, in the formula (VI) and the formula (VII), Y and Y ¹ represent the formula (20), the formula (21), the formula (22), the formula (23), A group represented by formula (24), formula (25), formula (26) or formula (27); a hydrogen atom in the group represented by the formula is a methyl group, a fluoro group, a chloro group or trifluoromethyl; Groups substituted by groups are preferred. R ³⁶ and R ³⁷ are each independently a hydroxyl group (—OH), a methoxy group (—OMe), an ethoxy group (—OEt), an n-propoxy group (—OPr), an n-butoxy group (— OBu) or chlorine atom (-Cl), preferably chlorine atom (-Cl).

In formula (20)-formula (29),
* 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 with a fluorine atom, and specific examples thereof include a phenylene group. From the viewpoint of easily improving the elastic modulus of the obtained optical film, in the formula (VI) and the formula (VII), Y and Y ¹ are respectively represented by the formula (26), the formula (28) or the formula (29) Groups are preferred. Further, ^{W 1,} from the viewpoint of easily suppressing the yellowness of the optical film, each independently, 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 —, —C (CH ₃ ) ₂ — or —C (CF _3). ) ₂ - more preferably, -C _{(CH 3) 2} - or -C _{(CF 3) 2} - and more preferably a.

  As the tetracarboxylic acid compound constituting the tetracarboxylic acid unit, aromatic tetracarboxylic acid and anhydride thereof, preferably aromatic tetracarboxylic acid compound such as dianhydride thereof; aliphatic tetracarboxylic acid and anhydride thereof, preferably Include aliphatic tetracarboxylic acid compounds such as dianhydrides. The tetracarboxylic acid compound may be a derivative of a tetracarboxylic acid compound such as acid chloride in addition to an anhydride, and these may be used alone or in combination of two or more.

Specific examples of the aromatic tetracarboxylic dianhydride include non-condensed polycyclic aromatic tetracarboxylic dianhydride, monocyclic aromatic tetracarboxylic dianhydride, and condensed polycyclic aromatic tetra Carboxylic dianhydrides are mentioned. As non-condensed polycyclic aromatic tetracarboxylic acid dianhydride, 4,4′-oxydiphthalic acid dianhydride, 3,3 ′, 4,4′-benzophenonetetracarboxylic acid dianhydride, 2,2 ′ , 3,3′-benzophenonetetracarboxylic dianhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 2,2 ′, 3,3′-biphenyltetracarboxylic dianhydride, 3,3 ', 4,4'-diphenylsulfone tetracarboxylic dianhydride, 2,2-bis (3,4-dicarboxyphenyl) propane dianhydride, 2,2-bis (2,3-dicarboxy) Phenyl) propane dianhydride, 2,2-bis (3,4-dicarboxyphenoxyphenyl) propane dianhydride, 4,4 ′-(hexafluoroisopropylidene) diphthalic dianhydride (also referred to as 6FDA) There), 1, -Bis (2,3-dicarboxyphenyl) ethane dianhydride, 1,1-bis (2,3-dicarboxyphenyl) ethane dianhydride, 1,2-bis (3,4-dicarboxyphenyl) ethane Dianhydride, 1,1-bis (3,4-dicarboxyphenyl) ethane dianhydride, bis (3,4-dicarboxyphenyl) methane dianhydride, bis (2,3-dicarboxyphenyl) methane Anhydrides, 4,4 '-(p-phenylenedioxy) diphthalic dianhydride and 4,4'-(m-phenylenedioxy) diphthalic dianhydride can be mentioned. Examples of the monocyclic aromatic tetracarboxylic dianhydride include 1,2,4,5-benzenetetracarboxylic dianhydride, and examples of the condensed polycyclic aromatic tetracarboxylic dianhydride include Includes 2,3,6,7-naphthalenetetracarboxylic dianhydride.
Among these, preferably 4,4′-oxydiphthalic dianhydride, 3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride, 2,2 ′, 3,3′-benzophenone tetracarboxylic dianhydride Anhydride, 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride, 2,2', 3,3'-biphenyltetracarboxylic dianhydride, 3,3 ', 4,4'-diphenyl Sulfonetetracarboxylic dianhydride, 2,2-bis (3,4-dicarboxyphenyl) propane dianhydride, 2,2-bis (2,3-dicarboxyphenyl) propane dianhydride, 2,2- Bis (3,4-dicarboxyphenoxyphenyl) propane dianhydride, 4,4 ′-(hexafluoroisopropylidene) diphthalic dianhydride, 1,2-bis (2,3-dicarboxyphenyl) ethane dianhydride Object, 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 acid dianhydride, more preferably 4,4'-oxydiphthalic acid dianhydride, 3,3', 4,4'-biphenyltetracarboxylic acid. Acid dianhydride, 2,2 ', 3,3'-biphenyltetracarboxylic acid dianhydride, 4,4'-(hexafluoroisopropylidene) diphthalic acid dianhydride, bis (3,4-dicarboxyphenyl) Methane dianhydride And 4,4 '-(p-phenylenedioxy) diphthalic dianhydride. These can be used alone or in combination of two or more.

  Examples of the aliphatic tetracarboxylic dianhydride include a cyclic or acyclic aliphatic tetracarboxylic dianhydride. The cycloaliphatic tetracarboxylic dianhydride is a tetracarboxylic dianhydride having an alicyclic hydrocarbon structure, and specific examples thereof include 1,2,4,5-cyclohexanetetracarboxylic dianhydride. , 1,2,3,4-cyclobutanetetracarboxylic acid dianhydride, 1,2,3,4-cyclopentanetetracarboxylic acid dianhydride such as cycloalkanetetracarboxylic acid dianhydride such as bicyclo [2.2 .2] Oct-7-ene-2,3,5,6-tetracarboxylic dianhydride, dicyclohexyl 3,3′-4,4′-tetracarboxylic dianhydride and their positional isomers. . These can be used alone or in combination of two or more. Specific examples of the acyclic aliphatic tetracarboxylic acid dianhydride include 1,2,3,4-butanetetracarboxylic acid dianhydride, 1,2,3,4-pentanetetracarboxylic acid dianhydride, etc. These may be used alone or in combination of two or more. Moreover, you may use combining a cycloaliphatic tetracarboxylic dianhydride and an acyclic aliphatic tetracarboxylic dianhydride.

  Among the tetracarboxylic acid compounds, the alicyclic tetracarboxylic acid dianhydride or the non-condensed polycyclic aromatic tetracarbon is preferable from the viewpoint of easily improving the elastic modulus, flex resistance and optical properties of the optical film. An acid dianhydride is mentioned. Specific examples thereof include 4,4′-oxydiphthalic dianhydride, 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride , 2,2 ', 3,3'-biphenyltetracarboxylic acid dianhydride, 3,3', 4,4'-diphenylsulfone tetracarboxylic acid dianhydride, 2,2-bis (3,4-diacetic acid) Carboxyphenyl) propane dianhydride, 4,4 '-(hexafluoroisopropylidene) diphthalic dianhydride, and mixtures thereof are preferred, and 3,3', 4,4'-biphenyl tetracarboxylic acid dianhydride and More preferred is 4,4 '-(hexafluoroisopropylidene) diphthalic dianhydride, and mixtures thereof, and more preferred is 4,4'-(hexafluoroisopropylidene) diphthalic dianhydride. Masui.

で表される化合物由来の構成単位（トリカルボン酸化合物（ＶＩＩＩ）由来の構成単位と称する場合がある）が挙げられる。トリカルボン酸化合物は、トリカルボン酸又はトリカルボン酸誘導体を示し、トリカルボン酸誘導体としては、例えばトリカルボン酸の酸クロリドやエステル体などが挙げられる。本発明のポリアミドイミド樹脂が、トリカルボン酸化合物（ＶＩＩＩ）由来の構成単位を含む場合、トリカルボン酸化合物（ＶＩＩＩ）由来の構成単位は、ジアミン化合物由来の構成単位と、Ｙ^２の両側に形成されたイミド基又はアミド基を介して結合し得る。トリカルボン酸単位として、トリカルボン酸単位（ＶＩＩＩ）が１種類又は２種類以上含まれていてもよく、２種類以上含まれる場合、それぞれのトリカルボン酸単位（ＶＩＩＩ）においてＹ^２の種類が異なる。また、Ｒ^３８は、−ＯＨ、−ＯＭｅ、−ＯＥｔ、−ＯＰｒ、−ＯＢｕ又は−Ｃｌであり、−Ｃｌであることが好ましい。Ｙ^２は、３価の有機基であり、好ましくは有機基中の水素原子が炭化水素基又はハロゲン原子で置換された炭化水素基で置換されていてもよい有機基である。Ｙ^２は、式（２０）、式（２１）、式（２２）、式（２３）、式（２４）、式（２５）、式（２６）、式（２７）、式（２８）又は式（２９）で表される基の結合手のいずれか１つが水素原子に置き換わった基、又は３価の炭素数６以下の鎖式炭化水素基を示す。 Examples of other tricarboxylic acid units include, for example, formula (VIII)

And a structural unit derived from the compound represented by (sometimes referred to as a structural unit derived from a tricarboxylic acid compound (VIII)). The tricarboxylic acid compound indicates tricarboxylic acid or a tricarboxylic acid derivative, and examples of the tricarboxylic acid derivative include acid chlorides and ester forms of tricarboxylic acid. Polyamideimide resin of the present invention, when containing a constitutional unit derived from tricarboxylic acid compound (VIII), tricarboxylic acid compound (VIII) constituent units derived has a constitutional unit derived from a diamine compound, formed on both sides of the Y ² It can be bonded through an imide group or an amide group. As the tricarboxylic acid unit, one type or two or more types of tricarboxylic acid units (VIII) may be included, and when two or more types are included, the type of Y ² is different in each tricarboxylic acid unit (VIII). ^Further, R 38 may, -OH, -OMe, -OEt, -OPr , a -OBu or -Cl, is preferably -Cl. Y ² is a trivalent organic group, and is preferably an organic group in which a hydrogen atom in the organic group may be substituted with a hydrocarbon group or a hydrocarbon group substituted with a halogen atom. Y ² is represented by the formula (20), the formula (21), the formula (22), the formula (23), the formula (24), the formula (25), the formula (26), the formula (27), the formula (28) or the formula (29) represents a group in which any one of the bonds of the group represented by (29) is replaced with a hydrogen atom, or a trivalent chain hydrocarbon group having 6 or less carbon atoms.

When the polyamideimide resin of the present invention contains a tricarboxylic acid unit, examples of the tricarboxylic acid compound constituting the tricarboxylic acid unit include aromatic tricarboxylic acid, aliphatic tricarboxylic acid, and derivatives thereof (for example, acid chloride, acid anhydride, etc.). Specific examples thereof include anhydrides of 1,2,4-benzenetricarboxylic acid; 2,3,6-naphthalenetricarboxylic acid-2,3-anhydride; phthalic anhydride and benzoic acid _{bond, -O -, - CH 2 -} , - C (CH 3) 2 -, - C (CF 3) 2 -, - SO 2 - or a compound linked phenylene group. These tricarboxylic acid compounds can be used alone or in combination of two or more.

で表される化合物由来の構成単位（ジアミン化合物（ＩＸ）由来の構成単位と称する場合がある）が挙げられる。ここで、本発明のポリアミドイミド樹脂において、ジアミン化合物（ＩＸ）由来の構成単位は、ジカルボン酸由来の構成単位と、Ｘの両側に形成されたアミド基を介して結合でき、テトラカルボン酸化合物由来の構成単位と、Ｘの両側に形成されたイミド基又はアミド基を介して結合でき、トリカルボン酸化合物由来の構成単位と、Ｘの両側に形成されたイミド基又はアミド基を介して結合できる。また、ジアミン単位として、ジアミン化合物（ＩＸ）由来の構成単位が１種類又は２種類以上含まれていてもよく、２種類以上含まれる場合、それぞれのジアミン化合物（ＩＸ）由来の構成単位においてＸの種類が異なる。Ｘは、２価の有機基を表し、好ましくは炭素数４〜４０の２価の有機基を表す。前記有機基は、有機基中の水素原子が炭化水素基又はハロゲン原子で置換された炭化水素基で置換されていてもよく、その場合、炭化水素基及びフッ素置換された炭化水素基の炭素数は好ましくは１〜８である。Ｘとしては、式（１０）、式（１１）、式（１２）、式（１３）、式（１４）、式（１５）、式（１６）又は式（１７）で表される基；それらの式で表される基中の水素原子がメチル基、フルオロ基、クロロ基又はトリフルオロメチル基で置換された基；又は炭素数６以下の鎖式炭化水素基を示す。 Other diamine units include, for example, formula (IX)

And a structural unit derived from a compound represented by (sometimes referred to as a structural unit derived from a diamine compound (IX)). Here, in the polyamideimide resin of the present invention, the structural unit derived from the diamine compound (IX) can be bonded to the structural unit derived from the dicarboxylic acid via the amide group formed on both sides of X, and derived from the tetracarboxylic acid compound. And a structural unit derived from a tricarboxylic acid compound can be bonded via an imide group or an amide group formed on both sides of X. In addition, as the diamine unit, one or more structural units derived from the diamine compound (IX) may be included, and in the case where two or more structural units are included, X in the structural unit derived from each diamine compound (IX). Different types. X represents a divalent organic group, preferably a divalent organic group having 4 to 40 carbon atoms. The organic group may be substituted with a hydrocarbon group in which a hydrogen atom in the organic group is substituted with a hydrocarbon group or a halogen atom, in which case the number of carbon atoms of the hydrocarbon group and the fluorine-substituted hydrocarbon group Is preferably 1 to 8. X is a group represented by formula (10), formula (11), formula (12), formula (13), formula (14), formula (15), formula (16) or formula (17); A group in which a hydrogen atom in the group represented by the formula is substituted with a methyl group, a fluoro group, a chloro group or a trifluoromethyl group; or a chain hydrocarbon group having 6 or less carbon atoms.

In formulas (10) to (17), * represents a bond,
V ^{1, V 2} and ^{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 —, —SO ₂ — or —CO— is represented.
In one example, V ¹ and V ³ are a single bond, —O— or —S—, and V ² is —CH ₂ —, —C (CH ₃ ) ₂ —, —C (CF ₃ ) _2. -Or -SO _2- . The bonding position of V ¹ and V ² with respect to each ring and the bonding position of V ² and V ³ with respect to each ring are preferably in the meta position or the para position with respect to each ring, respectively. It is more preferable that Further, V ¹ , V ² and V ³ are each independently a single bond, —O— or —S— from the viewpoint of easily improving the elastic modulus of the optical film comprising the polyamideimide resin. Preferably, it is a single bond or -O-.

  Examples of the diamine compound constituting the diamine unit include aliphatic diamines, aromatic diamines, and mixtures thereof. In the present embodiment, the “aromatic diamine” represents a diamine in which an amino group is directly bonded to an aromatic ring, and an aliphatic group or other substituent may be included in a part of the structure. The aromatic ring may be a single ring or a condensed ring, and examples thereof include, but are not limited to, a benzene ring, a naphthalene ring, an anthracene ring, and a fluorene ring. Among these, a benzene ring is preferable. Moreover, "aliphatic diamine" represents a diamine in which an amino group is directly bonded to an aliphatic group, and part of the structure thereof may contain an aromatic ring or another substituent.

  Specific examples of aliphatic diamines include acyclic aliphatic diamines such as hexamethylene diamine; 1,3-bis (aminomethyl) cyclohexane, 1,4-bis (aminomethyl) cyclohexane, norbornane diamine, 4,4 And cycloaliphatic diamines such as' -diaminodicyclohexylmethane. These can be used alone or in combination of two or more.

  Specific examples of the aromatic diamine include p-phenylenediamine, m-phenylenediamine, 2,4-toluenediamine, m-xylylenediamine, p-xylylenediamine, 1,5-diaminonaphthalene, 2,6-diamino An aromatic diamine having one aromatic ring, such as naphthalene; 4,4′-diaminodiphenylmethane, 4,4′-diaminodiphenylpropane, 4,4′-diaminodiphenyl ether, 3,4′-diaminodiphenyl ether, 3,3 '-Diaminodiphenylether, 4,4'-diaminodiphenylsulfone, 3,4'-diaminodiphenylsulfone, 3,3'-diaminodiphenylsulfone, 1,4-bis (4-aminophenoxy) benzene, 1,3-bis (4-Aminophenoxy) benzene, 4,4'-diaminodiphe 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, 2,2'-bis (trifluoromethyl) -4,4'-diaminodiphenyl (also referred to as TFMB) Some) 4,4'-bis (4-aminophenoxy) biphenyl, 9,9-bis (4-aminophenyl) fluorene, 9,9-bis (4-amino-3-methylphenyl) fluorene, 9,9- Two or more aromatic rings such as bis (4-amino-3-chlorophenyl) fluorene and 9,9-bis (4-amino-3-fluorophenyl) fluorene Aromatic diamines and the like. 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′-diaminodiphenyl ether, 3,3′-diaminodiphenyl ether, 4,4′-diaminodiphenyl sulfone, 3,3'-diaminodiphenyl sulfone, 1,4-bis (4-aminophenoxy) benzene, bis [4- (4-aminophenoxy) phenyl] sulfone, bis [4- (3-aminophenoxy) phenyl] sulfone, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, 2,2-bis [4- (3-aminophenoxy) phenyl] propane, 2,2′-dimethylbenzidine, 2,2′-bis (Trifluoromethyl) -4,4'-diaminodiphenyl, 4,4'-bis (4-aminophenyl) Xyl) biphenyl, more preferably 4,4′-diaminodiphenylmethane, 4,4′-diaminodiphenylpropane, 4,4′-diaminodiphenyl ether, 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 (trifluoromethyl) -4,4'-diaminodiphenyl, 4,4'-bis (4-aminophenoxy) biphenyl. These can be used alone or in combination of two or more.

  Among the above diamine compounds, it is easy to improve the mechanical strength (for example, bending resistance, elastic modulus) of the optical film and to improve the optical properties, for example, from the viewpoint of easily reducing the haze, from aromatic diamine having a biphenyl structure It is preferable to use one or more selected from the group consisting of: From 2,2'-dimethylbenzidine, 2,2'-bis (trifluoromethyl) -4,4'-diaminodiphenyl, 4,4'-bis (4-aminophenoxy) biphenyl and 4,4'-diaminodiphenyl ether It is more preferable to use one or more selected from the group consisting of 2,2′-bis (trifluoromethyl) -4,4′-diaminodiphenyl.

  The content of the dicarboxylic acid unit contained in the carboxylic acid unit constituting the polyamideimide resin is preferably 20 mol% or more, more preferably 30 mol% or more, based on the total number of moles of all the carboxylic acid units. More preferably, it is 40 mol% or more, particularly preferably 50 mol% or more, most preferably 60 mol% or more, preferably 90 mol% or less, more preferably 85 mol% or less, still more preferably 80 mol% or less . When the content of the dicarboxylic acid unit is equal to or more than the above lower limit, the mechanical strength (for example, elastic modulus) of the optical film is likely to be improved due to hydrogen bonding between amide bonds derived from the dicarboxylic acid unit. In addition, when the content of the dicarboxylic acid unit is less than or equal to the above upper limit, the viscosity of the polyamideimide varnish described later can be suppressed by suppressing the thickening due to the hydrogen bond between the amide bonds derived from the dicarboxylic acid unit. And processing of the optical film can be facilitated.

  The content of the tetracarboxylic acid unit contained in the carboxylic acid unit constituting the polyamideimide resin is preferably 10 mol% or more, more preferably 20 mol% or more, preferably with respect to the total number of moles of the carboxylic acid unit. Is 60 mol% or less, more preferably 50 mol% or less, still more preferably 40 mol% or less. There exists a tendency which can improve mechanical strength (for example, elasticity modulus) as content of a tetracarboxylic acid unit is below said upper limit. When the content of the tetracarboxylic acid unit is equal to or more than the above lower limit, the solubility in a solvent and the optical properties (for example, haze and yellowness) tend to be improved.

  The content of the dicarboxylic acid unit in the carboxylic acid unit contained in the above polyamideimide resin is preferably 0.1 mol or more, more preferably 1 mol or more, still more preferably 2 mol, per 1 mol of the tetracarboxylic acid unit. It is above, Preferably it is 5 mol or less, More preferably, it is 4 mol or less, More preferably, it is 3 mol or less. When the content of the dicarboxylic acid unit is equal to or more than the above lower limit, the optical film tends to have high mechanical strength (e.g., elastic modulus), and the amide bond in the dicarboxylic acid unit is equal to or less than the above upper limit In the meantime, the increase in viscosity due to hydrogen bonding can be suppressed, the viscosity of the polyamideimide varnish can be reduced, and the production of the optical film becomes easy.

The content (R _(I) ) of the structural unit derived from the compound represented by formula (I) (the structural unit derived from the dicarboxylic acid compound _(I) ) is the total number of moles of all the structural units constituting the polyamideimide resin. Preferably, it is more than 0 mol%, more preferably 5 mol% or more, still more preferably 10 mol% or more, particularly preferably 15 mol% or more, most preferably 20 mol% or more, especially 25 mol% or more. Preferably it is 40 mol% or less, More preferably, it is 35 mol% or less. Further, the content of the constituent unit derived from the compound represented by the formula (I) (the constituent unit derived from the dicarboxylic acid compound (I)) is relative to the total number of moles of carboxylic acid units constituting the polyamideimide resin. It is preferably more than 0 mol%, more preferably 10 mol% or more, still more preferably 20 mol% or more, particularly preferably 30 mol% or more, most preferably 40 mol% or more, especially 50 mol% or more, preferably It is 80 mol% or less, More preferably, it is 70 mol% or less. When the content of the structural unit derived from the dicarboxylic acid compound (I) is not less than the above lower limit value, the mechanical strength of the optical film (by the structural rigidity derived from the structural unit derived from the dicarboxylic acid compound (I) ( For example, it is easy to improve the elastic modulus), and the polyamideimide mentioned below is suppressed by suppressing thickening due to hydrogen bond between amide bonds derived from the structural unit derived from the dicarboxylic acid compound (I) to be below the above upper limit. The viscosity of the varnish can be suppressed and the processing of the optical film can be facilitated. In addition, in this specification, content (mol%) of the structural unit derived from the compound represented by said Formula (I) with respect to the total number-of-moles of all the structural units which comprise polyamidoimide resin is called R _(I) .

  The content of the structural unit derived from the compound represented by the formula (II) (the structural unit derived from the tetracarboxylic acid compound (II)) is preferably relative to the total number of moles of all the structural units constituting the polyamideimide resin. It is 5 mol% or more, more preferably 10 mol% or more, preferably 30 mol% or less, more preferably 25 mol% or less, and further preferably 20 mol% or less. The content of the structural unit derived from the compound represented by the formula (II) (the structural unit derived from the tetracarboxylic acid compound (II)) is based on the total number of moles of the carboxylic acid units constituting the polyamideimide resin. Preferably it is 10 mol% or more, More preferably, it is 20 mol% or more, Preferably it is 60 mol% or less, More preferably, it is 50 mol% or less, More preferably, it is 40 mol% or less. When the content of the structural unit derived from the tetracarboxylic acid compound (II) is not less than the above lower limit value, the mechanical strength (for example, the elastic modulus) of the optical film is easily improved, and is not more than the above upper limit value In addition, it is easy to improve the solubility in solvents and optical properties (for example, the haze and the degree of yellowness).

  The content of the structural unit derived from the compound represented by the formula (III) (the structural unit derived from the diamine compound (III)) is preferably 20 moles relative to the total number of moles of all structural units constituting the polyamideimide resin. % Or more, more preferably 30 mol% or more, further preferably 40 mol% or more, particularly preferably 45 mol% or more, preferably 80 mol% or less, more preferably 70 mol% or less, still more preferably 60 mol%. Hereinafter, it is particularly preferably 55 mol% or less. The content of the structural unit derived from the compound represented by formula (III) (the structural unit derived from the diamine compound (III)) is preferably 30 with respect to the total number of moles of the diamine units constituting the polyamideimide resin. More than mol%, More preferably, it is 50 mol% or more, More preferably, it is 70 mol% or more, Preferably it is 100 mol% or less. When the content of the constituent unit derived from the diamine compound (III) is in the above range, the bending resistance and the transparency of the optical film are likely to be improved, and the solubility of the polyamideimide resin in the solvent is further improved. The viscosity of the varnish can be suppressed to a lower level, and the production of the optical film is facilitated.

  The content of the structural unit derived from the compound represented by the formula (IV) (the structural unit derived from the dicarboxylic acid compound (IV)) is preferably 1 with respect to the total number of moles of all the structural units constituting the polyamideimide resin. 0.5 mol% or more, more preferably 2.5 mol% or more, further preferably 3.5 mol% or more, particularly preferably 5 mol% or more, preferably 35 mol% or less, more preferably 30 mol% or less. It is. The content of the structural unit derived from the dicarboxylic acid compound (IV) is preferably 3 mol% or more, more preferably 5 mol% or more, and more preferably 5 mol% or more, based on the total number of moles of the carboxylic acid units constituting the polyamideimide resin. Preferably it is 7 mol% or more, Especially preferably, it is 10 mol% or more, Preferably it is 70 mol% or less, More preferably, it is 65 mol% or less, More preferably, it is 60 mol% or less. When the content of the structural unit derived from the dicarboxylic acid compound (IV) is equal to or more than the above lower limit value, the bending resistance is easily improved, and when the content is equal to or less than the above upper value value, the dicarboxylic acid compound (IV) derived By suppressing the thickening due to the hydrogen bond between the amide bonds derived from the structural unit, the viscosity of the polyamideimide varnish described later can be suppressed, and the processing of the optical film can be facilitated.

  In a preferred embodiment of the present invention, the polyamideimide resin may contain a halogen atom as described above. Specific examples of the fluorine-containing substituent include a fluoro group and a trifluoromethyl group. When the polyamideimide resin contains a halogen atom, the transparency of the optical film containing the polyamideimide resin is easily improved. From the viewpoint of the transparency of the optical film, the halogen atom is preferably a fluorine atom.

  The content of halogen atoms in the polyamideimide resin is preferably 1 to 40% by mass, more preferably 3 to 35% by mass, based on the mass of the polyamideimide resin, from the viewpoint of easily improving the transparency of the optical film. More preferably, it is 5-32 mass%.

  The polyamideimide resin of the present invention is produced, as described above, by reacting the dicarboxylic acid compound, the tetracarboxylic acid compound, and, if necessary, the carboxylic acid compound containing the tricarboxylic acid compound, and the diamine compound. Is done. In particular, a compound represented by formula (I), a compound represented by formula (II), a compound represented by formula (III), and a compound represented by formula (IV) as necessary. And other carboxylic acids and other diamines, such as polycondensation. In one embodiment of the present invention, an imidization catalyst may be present in the synthesis of the polyamideimide resin. Examples of the imidization catalyst include aliphatic amines such as tripropylamine, dibutylpropylamine and ethyldibutylamine; N-ethyl piperidine, N-propyl piperidine, N-butyl pyrrolidine, N-butyl piperidine, and N-propyl hexahydro Alicyclic amines such as azepine (monocyclic); azabicyclo [2.2.1] heptane, azabicyclo [3.2.1] octane, azabicyclo [2.2.2] octane, and azabicyclo [3.2. 2] Alicyclic amines (polycyclic) such as nonane; 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 aromatic amines isoquinoline.

  In the production of the polyamideimide resin, the reaction temperature is not particularly limited, but is, for example, 50 to 350 ° C. Although reaction time is not specifically limited, For example, it is about 30 minutes-10 hours. If necessary, the reaction may be carried out under an inert atmosphere or under reduced pressure. Further, the reaction may be carried out in a solvent, and examples of the solvent include a solvent described later used for preparing a polyamideimide varnish.

  In the polyamideimide resin, the weight average molecular weight in terms of standard polystyrene is preferably 210,000 or more, more preferably 300,000 or more, further preferably 350,000 or more, preferably 750,000 or less, more preferably. Is 600,000 or less, more preferably 500,000 or less. When the weight average molecular weight of the polyamideimide resin is not less than the above lower limit, the bending resistance of the optical film containing the polyamideimide resin can be improved. In addition, when the weight average molecular weight of the polyamideimide resin is less than or equal to the above upper limit, the viscosity of the polyamideimide varnish can be suppressed low, and the stretching of the optical film is easy, so the processability becomes good. In the present specification, the weight average molecular weight can be determined, for example, by GPC measurement and converted to standard polystyrene, and specifically, it can be determined by the method described in the examples.

  In the optical film, the content of the polyamideimide resin is preferably 30 to 99% by mass, more preferably 35 to 95% by mass, still more preferably 40 to 90% by mass, and particularly preferably 50% with respect to the mass of the optical film. It is -90 mass%. When the content of the polyamideimide resin is in the above range, an optical film excellent in bending resistance and transparency is easily obtained.

  More specifically, the polyamideimide resin according to the preferred embodiment of the present invention has the repeating structural unit represented by the formula (30) and the repeating structural unit represented by the formula (33). Furthermore, the polyamide-imide resin according to a preferred embodiment of the present invention is a repeat represented by any one of the formula (31) and the formula (32) as long as various physical properties of the obtained polyamide-imide polymer film are not impaired. Any one or more of the structural units may be included. In addition, the polyamideimide resin may contain two or more types of the repeating structural units represented by Formula (30), Formula (31), Formula (32), and Formula (33). The repeating structural unit represented by the formula (33) is a structural unit formed by the reaction of a dicarboxylic acid compound and a diamine compound, and shows both a structural unit derived from a dicarboxylic acid compound and a structural unit derived from a diamine compound. Unit. The repeating structural unit represented by the formula (30) is a structural unit formed by the reaction of a tetracarboxylic acid compound and a diamine compound, and a structural unit derived from a tetracarboxylic acid compound and a structural unit derived from a diamine compound It is a structural unit shown together. The repeating structural unit represented by the formula (32) is a structural unit formed by the reaction of a tricarboxylic acid compound and a diamine compound, and shows both a structural unit derived from the tricarboxylic acid compound and a structural unit derived from the diamine compound. Unit. The repeating structural unit represented by the formula (31) is a structural unit formed by the reaction of a tetracarboxylic acid compound and a diamine compound, and a structural unit derived from a tetracarboxylic acid compound and a structural unit derived from a diamine compound It is a structural unit shown together.

In formulas (30) to (33), K ¹ and K ³ represent Y in formula (b), formula (VI) or Y ¹ in formula (VII), and K ² represents formula (a), formula (d) Or Z in Formula (V), K ⁴ represents Y ² in Formula (VIII), and L ^{1 to} L ⁴ each represent X in Formula (c) or Formula (IX).

^R 3 to R ⁶ in the formula (a) is the same as ^R 3 to R ⁶ in formula (I), ^R 7 ^{~R 14} in the formula (b) and ^R 7 ^{to R 14} in formula (II) the same, ^R 15 ^{to R 22} in the formula (c) is the same as ^R 15 ^{to R 22} in formula (III), ^R 25 in the formula (d) ^{to R 32} is ^{R 25} in formula (IV) It is similar to to R ^32, * represents a bond.

<Silica particles>
The optical film of the present invention may contain silica particles. The average primary particle diameter of the silica particles is preferably 10 nm or more, more preferably 15 nm or more, still more preferably 20 nm or more, preferably 100 nm or less, more preferably 80 nm or less, still more preferably 60 nm or less, particularly preferably 40 nm or less It is. When the average primary particle diameter of the silica particles is in the above range, the aggregation of the silica particles can be suppressed, the transparency of the optical film can be improved, and the bending resistance can also be improved. Moreover, even if the thickness of an optical film is comparatively thick as the average primary particle diameter of a silica particle is below said upper limit, a haze value is easy to be reduced. In particular, when the average primary particle diameter of the silica particles is preferably 80 nm or less, more preferably 60 nm or less, for example, even if the thickness of the optical film is 30 μm or more, the low haze value is preferably 1.0% or less Preferably, a haze value of 0.8% or less (corresponding to Hz _b ) can be shown. In the present invention, the average primary particle diameter can be measured by the BET method.

<Optical film>
The optical film of the present invention comprises the polyamideimide resin, and has the formula (1)
ΔHz <0.5 (1)
[In the formula (1), ΔHz represents Hz _a -Hz _b , and Hz _a is a mandrel test that is bent once at a bending radius of 1 mm at room temperature to return to a flat shape (conforms to JIS K 5600-5-1: 1999). The haze (%) of the subsequent optical film is represented, and Hz _b represents the haze (%) of the optical film before the mandrel test.
Meet the relationship. Since the optical film of the present invention satisfies the relationship of the formula (1), it has excellent bending resistance and excellent optical property stability under high temperature and high humidity. Moreover, the optical film of the present invention has a low haze and is excellent in transparency. That is, the optical film of the present invention can maintain excellent optical properties such as transparency without being easily scratched, cracked, clouded or the like even if the optical film is continuously bent and returned. . Moreover, even if the optical film is stored in a bent state under an environment of high temperature and high humidity, for example, at a temperature of 85 ° C. and a relative humidity of 85%, the optical film is less likely to be scratched, cracked, clouded, etc. Excellent optical properties can be maintained. Therefore, the optical film of the present invention can be used as a member of an image display device, particularly as a front plate (window film) of a flexible display. In order to use it for the front plate (window film) of a flexible display, from the viewpoint of durability during repeated use, the ΔHz ′ before and after storage for 24 hours in an environment of a temperature of 85 ° C. and a relative humidity of 85% is 0.4. Less than, preferably 0.3 or less, more preferably 0.2 or less. ΔHz ′ can be measured and calculated by the method described in the examples.

The front plate has a function of protecting the image display element in the flexible display.
Examples of the image display device include wearable devices such as a television, a smartphone, a mobile phone, a car navigation, a tablet PC, a portable game machine, electronic paper, an indicator, a bulletin board, a clock, and a smart watch. The flexible display includes an image display device having flexible characteristics, such as a television, a smartphone, a mobile phone, a car navigation system, a tablet PC, a portable game machine, an electronic paper, an indicator, a bulletin board, a watch, and a wearable device.

In the formula (1), ΔHz represents Hz _a -Hz _b , and the Hz _a is the haze (%) of the optical film after the mandrel test that is bent once at a bending radius of 1 mm and returned immediately after it at room temperature and in the atmosphere. Represents. More specifically, ΔHz can be measured and calculated by the method described in the examples. Hz _b represents the haze (%) of the optical film before the mandrel test. ΔHz shows the change amount of the haze of the optical film before and after the mandrel test (flexibility test), and the smaller the value is, the higher the stability of the optical characteristics in bending is. In addition, the composition of the optical film, for example, the type and composition ratio of the repeating structure constituting the polyamideimide resin constituting the optical film, and the type and content of additives such as silica particles and ultraviolet absorber contained in the optical film; The thickness of the optical film; or the manufacturing conditions of the optical film, for example, the type of varnish solvent, the drying temperature, the drying time, and the like can be adjusted as appropriate to the range of formula (1). In particular, when silica particles having an average primary particle diameter of not more than the above upper limit are used, the transparency becomes good, so that the range of the formula (1) can be easily adjusted.

In the formula (1), Hz _b is usually preferably 20.0% or less, more preferably 2.0% or less, still more preferably 1.0% or less, and particularly preferably 0.8% or less. When it is in the above range, the optical film can have good transparency, and can contribute to high visibility when used for a front plate of an image display device. Also, ΔHz is less than 0.5%, more preferably 0.4% or less, further preferably 0.3% or less, and still more preferably 0.1% or less. When ΔHz is in the above range, the optical film has better bending resistance, and optical properties such as transparency can be effectively maintained even under high temperature and high humidity.

Further, the optical film of the present invention preferably contains the silica particles, and the formula (2)
0 <R _Si ≦ 32 + 2/3 × R _(I) (2)
[In formula (2), R _Si represents the content (% by mass) of silica particles relative to the mass of the optical film, and R _(I) represents the formula (I) relative to the total number of moles of all structural units constituting the polyamideimide resin. Represents the content (mol%) of the constituent unit derived from the compound represented by
It is preferable to satisfy the following relationship.

In the formula (2), R _Si is preferably 5% by mass or more, more preferably 10% by mass or more, further preferably 15% by mass or more, preferably less than 60% by mass, more preferably 50% by mass or less is there. When the silica particle content is not less than the above lower limit, the elastic modulus and flex resistance of the optical film can be further improved, and when the silica particle content is not more than the above upper limit, for example, haze is reduced. , Can improve transparency. In one embodiment, the optical film of the present invention can suppress aggregation of the silica particles even when the content of the silica particles is relatively large, and can ensure good transparency, and the optical property under high temperature and high humidity Since it is excellent in stability of characteristics and good bending resistance is obtained, R _Si can be 20 parts by mass or more, 30 parts by mass or more, 40 parts by mass or more, and 50 parts by mass or more.

  The optical film of the present invention can further contain an ultraviolet absorber. Examples of UV absorbers include benzotriazole derivatives (benzotriazole-based UV absorbers), triazine derivatives such as 1,3,5-triphenyltriazine derivatives (triazine-based UV absorbers), benzophenone derivatives (benzophenone-based UV absorbers) ) And salicylate derivatives (salicylate-based ultraviolet absorbers), and at least one selected from the group consisting of these can be used. It is preferable to use at least one selected from the group consisting of a benzotriazole-based ultraviolet absorber and a triazine-based ultraviolet absorber from the viewpoint of having a good ultraviolet absorptivity, and a benzotriazole-based ultraviolet absorber is more preferable.

  Specific examples of the benzotriazole ultraviolet absorber include a compound represented by the formula (A), and these can be used alone or in combination of two or more. As a specific example of a compound represented by Formula (A), the Sumitomo Chemical Co., Ltd. product name: Sumisorb (trademark) 200 (2- (2-hydroxy-5- methylphenyl) benzotriazole), Sumisorb 300 (2- (3-tert-butyl-2-hydroxy-5-methylphenyl) -5-chlorobenzotriazole), Sumisorb 340 (2- (2-hydroxy-5-tert-octylphenyl) benzotriazole), Sumisorb 350 (2- (2-hydroxy3,5-di-tert-pentylphenyl) benzotriazole).

In formula (A), T is a hydrogen atom, a fluorine atom, a chlorine atom, an alkyl group having 1 to 5 carbon atoms or an alkoxy group having 1 to 5 carbon atoms, and R ³⁹ and R ⁴⁰ are each independently a hydrogen atom. or a hydrocarbon group having 1 to 20 carbon ^atoms, at least one of ^{R 39} or ^{R 40} is a hydrocarbon group having 1 to 20 carbon atoms.

Examples of the alkyl group having 1 to 5 carbon atoms in T include methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, n-pentyl, and 2-methyl. -Butyl group, 3-methylbutyl group, 2-ethyl-propyl group and the like can be mentioned.
As a C1-C5 alkoxy group in T, a methoxy group, an ethoxy group, n-propoxy group, isopropoxy group, n-butoxy group, sec-butoxy group, tert-butoxy group, n-pentyloxy group, 2 -Methyl-butoxy group, 3-methylbutoxy group, 2-ethyl-propoxy group and the like.
T is preferably a hydrogen atom, a fluorine atom, a chlorine atom or a methyl group, more preferably a hydrogen atom, a fluorine atom or a chlorine atom.

R ³⁹ and R ⁴⁰ are each a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms, and at least one of R ³⁹ and R ⁴⁰ is a hydrocarbon group. When each of R ³⁹ and R ⁴⁰ is a hydrocarbon group, it is preferably a hydrocarbon group having 1 to 12 carbon atoms, and more preferably a hydrocarbon group having 1 to 8 carbon atoms. Specific examples include a methyl group, a tert-butyl group, a tert-pentyl group, and a tert-octyl group.

  In the optical film, the content of the ultraviolet light absorber is preferably 0.01 to 10 parts by mass, more preferably 1 to 8 parts by mass, still more preferably 100 parts by mass of the total mass of the polyamideimide resin and the silica particles. Is 3-7 parts by mass. When the content of the ultraviolet absorber is equal to or more than the above lower limit, the ultraviolet absorptivity can be improved. When the content of the ultraviolet absorber is not more than the above upper limit, decomposition of the ultraviolet absorber due to heat during the production of the optical film can be suppressed, and the transparency of the optical film is easily improved.

  The optical film of the present invention may contain additives other than the polyamideimide resin, the silica particles, and the ultraviolet absorber. Examples of other additives include resins other than polyamideimide resins, antioxidants, mold release agents, stabilizers, coloring agents such as bluing agents, flame retardants, lubricants, and leveling agents. Other additives can be used alone or in combination of two or more. When the optical film contains an additive, the content of the additive is preferably 0.01 to 20% by mass, more preferably 0.1 to 10% by mass with respect to the mass of the optical film.

  Other resins are not particularly limited, and commonly used resins such as polyolefin resins, cellulose resins, polyester resins, polycarbonate resins, (meth) acrylic resins, polystyrene resins, polyether ether ketone resins, polysulfone Resin, polyimide resin and the like. Other resins can be used alone or in combination of two or more.

  The thickness of the optical film is appropriately adjusted depending on the application, but is usually 10 to 200 μm, preferably 20 to 100 μm, more preferably 25 to 80 μm, and still more preferably 30 to 50 μm. When the thickness of the optical film is in the above range, the bending resistance and the transparency become good. In the present invention, the thickness of the optical film can be measured, for example, by the method described in the examples.

  In the optical film of the present invention, the total light transmittance at a thickness of 50 μm is preferably 80% or more, more preferably 85% or more, still more preferably 90% or more, particularly preferably 91% or more, and most preferably 92% or more. is there. The optical film in which the total light transmittance of the optical film is not less than the above lower limit has good transparency, and can contribute to high visibility when used for a front plate of an image display device. Further, the upper limit of the total light transmittance is usually 99.99% or less. The total light transmittance can be measured by, for example, a fully automatic direct reading haze computer HGM-2DP manufactured by Suga Test Instruments Co., Ltd. or an ultraviolet-visible near-red spectrophotometer V-670 manufactured by JASCO Corporation. When the optical film is applied to, for example, a liquid crystal display device, it is the same on the viewing side even if the power of the light source such as a backlight is reduced compared to the case where the transmittance is low due to the high transmittance of the film. Brightness can be obtained.

The elastic modulus of the optical film of the present invention is preferably 3 GPa or more, more preferably 4 GPa or more, still more preferably 5 GPa or more, particularly preferably 6 GPa or more, preferably 10 GPa or less, more preferably 8 GPa or less, more preferably 7 GPa It is as follows.
When the elastic modulus of the optical film is within the above range, the bending resistance of the optical film is likely to be improved.
For the elastic modulus, for example, using an autograph AG-IS manufactured by Shimadzu Corporation, measure an S-S curve of a test piece of 10 mm width under a distance of 500 mm between chucks and a tensile speed of 20 mm / min. It can be measured from the slope.

Although the manufacturing method of an optical film is not specifically limited, For example, the following processes:
(A) a step (polyamideimide varnish preparation step) of preparing a liquid containing a polyamideimide resin and silica particles (sometimes referred to as a polyamideimide varnish);
(B) A step of applying a polyamideimide varnish to a substrate to form a coating film (application step), and (c) a step of drying the applied liquid (coating film) to form an optical film (optical film). Formation process)
It can manufacture by the method containing.

In the polyamideimide varnish preparation step, the dicarboxylic acid compound, the tetracarboxylic acid compound, the diamine compound, and, if necessary, the tricarboxylic acid compound, which acts as an imidization catalyst, for the preparation of the polyamideimide varnish Other components such as tertiary amine and dehydrating agent are mixed and reacted to prepare a polyamideimide resin mixed solution.
Examples of the tertiary amine include the aromatic amines and aliphatic amines described above. As the dehydrating agent, acetic anhydride, propionic anhydride, isobutyric anhydride, pivalic anhydride, butyric anhydride, isovaleric anhydride and the like can be mentioned. A poor solvent is added to the polyamideimide resin mixed solution to precipitate a polyamideimide resin by a reprecipitation method, and the precipitate is taken out by drying. If necessary, the precipitate is washed with a solvent such as methanol and dried to obtain a polyamideimide resin. Then, a polyamideimide resin is dissolved in a solvent, and the silica particles and, if necessary, the ultraviolet absorber and the other additives are added and stirred to prepare a polyamideimide varnish. In addition, a silica sol in which a dispersion medium of silica sol containing silica particles is replaced with a solvent capable of dissolving the polyamide imide resin, for example, a solvent used for preparing the following polyamide imide varnish, may be added to the polyamide imide resin.

  The solvent used for the preparation of the polyamideimide varnish is not particularly limited as long as it can dissolve the polyamideimide resin. Examples of such solvents include amide solvents such as N, N-dimethylacetamide and N, N-dimethylformamide; lactone solvents such as γ-butyrolactone and γ-valerolactone; and sulfur-containing solvents such as dimethylsulfone, dimethylsulfoxide and sulfolane Examples thereof include carbonate solvents such as ethylene carbonate and propylene carbonate; and combinations (mixed solvents) thereof. Among these solvents, lactone solvents such as γ-butyrolactone and γ-valerolactone are preferable for preparing a varnish to which silica sol is added. The polyamideimide varnish may contain water, alcohol solvents, ketone solvents, acyclic ester solvents, ether solvents and the like.

  In the coating step, a polyamideimide varnish is coated on the substrate by a known coating method to form a coating film. Examples of known coating methods include wire bar coating, roll coating such as reverse coating and gravure coating, die coating, comma coating, lip coating, spin coating, screen coating, fountain coating, dipping, Examples thereof include a spray method and a fluent molding method.

  In an optical film formation process, an optical film can be formed by drying a coating film and peeling from a base material. You may perform the drying process which dries an optical film further after peeling. The coating film can be dried usually at a temperature of 50 to 350 ° C. If necessary, the coating may be dried under inert atmosphere or reduced pressure conditions.

  Examples of the substrate include a PET film, a PEN film, a polyimide film, and a polyamideimide film. Among these, from the viewpoint of excellent heat resistance, a PET film, a PEN film, a polyimide film, and other polyamideimide films are preferable. Furthermore, a PET film is more preferable from the viewpoints of adhesion to an optical film and cost.

It is also possible to form a laminated film obtained by adding a functional layer such as a hard coat layer, an adhesive layer, or a hue control layer to the optical film of the present invention.
Furthermore, when the optical film of the present invention is used for mounting on a display device, a protective film can be bonded to the surface of the film in order to prevent contamination of the film during transportation of the optical film.

  EXAMPLES Hereinafter, although this invention is demonstrated more concretely based on an Example and a comparative example, this invention is not limited to a following example. Unless otherwise stated, "%" and "parts" in the examples mean% by mass and parts by mass. First, measurement and evaluation methods will be described.

<ΔHz at room temperature (25 ° C.)>
The optical films obtained in Examples and Comparative Examples were cut into a size of 68 mm × 28 mm using a dumbbell cutter, and a mandrel was used using a haze computer (“HGM-2DP” manufactured by Suga Test Instruments Co., Ltd.). The haze Hz _b (%) of the optical film before the test was measured.
Thereafter, the following mandrel test (in accordance with JIS K 5600-5-1: 1999) was performed to measure Hz _a (%). First, at a room temperature (25 ° C.), a portion where the haze Hz _b (%) of the optical film was measured was bent evenly along a cylindrical mandrel having a bending radius of 1 mm. Immediately after that (after 1 to 2 seconds), the folded optical film was returned to a planar shape, and the haze Hz _a (%) of the bent portion of the planar optical film was measured. From the measurement results, Δ Hz (= Hz _a − Hz _b ) was calculated and evaluated as follows.
○ ... Δ Hz <0.5
× ... ΔHz 0.5 0.5

<ΔHz 'at 85 ° C and 85% relative humidity storage>
The optical films obtained in Examples and Comparative Examples were cut into a size of 68 mm × 28 mm using a dumbbell cutter, and obtained using a haze computer (“HGM-2DP” manufactured by Suga Test Instruments Co., Ltd.). The haze Hz _d (%) of the obtained optical film was measured. Thereafter, the following durability test was performed, and Hz _c (%) after the test was measured. First, an optical film obtained by bending the portion at which the haze Hz _d (%) was measured with a bending radius of 1 mm was introduced into a constant temperature and humidity environment resistance testing machine (“CL09-type01D01-FSC90” manufactured by Yuasa System Co., Ltd.). The optical film was stored for 24 hours under an environment of a temperature of 85 ° C. and a relative humidity of 85%, a bending radius of 1 mm (both ends of the folded optical film were kept parallel). Thereafter, the folded optical film was returned to a planar shape, and was placed for 30 minutes in an environment of 30 ° C. and 50% relative humidity. The haze Hz _c (%) of the portion where the flat optical film was bent was measured. From the measurement results, ΔHz ′ (= Hz _c −Hz _d ) was calculated and evaluated as follows.
○ ... ΔHz '<0.4
× ... ΔHz '0.4 0.4

<Flexibility test>
The optical films obtained in Examples and Comparative Examples were cut into a size of 10 mm × 100 mm using a dumbbell cutter. The cut film is set on the MIT folding fatigue tester ("MIT-DA" manufactured by Toyo Seiki Seisakusho Co., Ltd., model: 0530) main body, test speed 175 cpm, bending angle 135 °, load 750 g, R 1 of bending clamp A bending test in both directions was performed under the condition of 0.0 mm, and the number of bending resistances (number of times the film could be bent without breaking) was measured. It evaluated as follows.
○: The bending resistance is 10,000 times or more, which is good.
X: Bending resistance is less than 10,000 times, which is defective.

<Weight average molecular weight (Mw)>
Gel Permeation Chromatography (GPC) Measurement / Pretreatment Method DMF eluent (10 mmol solution of lithium bromide) was added to the polyamideimide resin obtained in Examples and Comparative Examples to a concentration of 2 mg / mL, and the solution was heated to 80 ° C. The solution was heated with stirring for 30 minutes, cooled, and filtered through a 0.45 μm membrane filter to obtain a measurement solution.
Measurement conditions Column: TSKgel SuperAWM-H × 2 + SuperAW2500 × 1 (6.0 mm ID × 150 mm × 3)
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

<Thickness of optical film>
The thickness of the optical film obtained in Examples and Comparative Examples was measured using an ABS Digimatic Indicator (manufactured by Mitutoyo, "ID-C112BS").

(Preparation of silica sol)
Amorphous silica sol having a BET diameter (average primary particle diameter measured by BET method) of 27 nm prepared by the sol-gel method is used as a raw material, and γ-butyrolactone (hereinafter sometimes referred to as GBL) substitution by solvent substitution A silica sol was prepared. The obtained sol was filtered with a membrane filter having a pore size of 10 μm to obtain a GBL-substituted silica sol. The obtained GBL-substituted silica sol had a silica component (inorganic particles) of 30% by mass.

(Preparation of Polyamideimide Resin)
1. Synthesis example 1
Under a nitrogen gas atmosphere, in a 1 L separable flask equipped with a stirring blade, 65 g (202.97 mmol) of 2,2′-bis (trifluoromethyl) -4,4′-diaminodiphenyl (TFMB) and N, N-dimethyl were added. 834.69 g of acetamide (DMAc) was added, and TFMB was dissolved in DMAc while stirring at room temperature. Next, 27.09 g (60.98 mmol) of 4,4 ′-(hexafluoroisopropylidene) diphthalic acid dianhydride (6FDA) was added to the flask and stirred at room temperature for 3 hours. Thereafter, 12.00 g (40.66 mmol) of 4,4'-oxybis (benzoyl chloride) (OBBC) and then 20.63 g (101.64 mmol) of terephthaloyl chloride (TPC) are added to the flask and stirred at room temperature for 1 hour did. Next, 6.63 g (71.15 mmol) of 4-methylpyridine and 18.68 g (182.95 mmol) of acetic anhydride were added to the flask, stirred at room temperature for 30 minutes, then heated to 70 ° C. using an oil bath, The mixture was further stirred for 3 hours to obtain a reaction solution.
The resulting reaction solution was cooled to room temperature, charged into a large amount of methanol in a thread form, and the deposited precipitate was taken out, immersed in methanol for 6 hours, and then washed with methanol. Next, the precipitate was dried under reduced pressure at 100 ° C. to obtain a polyamideimide resin (TPC / 6FDA / OBBC / TFMB = 50/30/20/100). The weight average molecular weight (Mw) of the polyamideimide resin was 310,000.

2. Synthesis example 2
Under a nitrogen gas atmosphere, 40 g (124.91 mmol) of TFMB and 682.51 g of DMAc were added to a 1 L separable flask equipped with a stirring blade, and TFMB was dissolved in DMAc while stirring at room temperature. Next, 16.78 g (37.77 mmol) of 6FDA was added to the flask and stirred at room temperature for 3 hours. Thereafter, 3.72 g (12.59 mmol) of OBBC and then 15.34 g (75.55 mmol) of TPC were added to the flask and stirred at room temperature for 1 hour. Next, 8.21 g (88.14 mmol) of 4-methylpyridine and 15.43 g (151.10 mmol) of acetic anhydride were added to the flask, and after stirring for 30 minutes at room temperature, the temperature was raised to 70 ° C. using an oil bath, The mixture was further stirred for 3 hours to obtain a reaction solution.
The resulting reaction solution was cooled to room temperature, poured into a large amount of methanol in the form of a thread, 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 (TPC / 6FDA / OBBC / TFMB = 60/30/10/100). The weight average molecular weight (Mw) of the polyamideimide resin was 400,000.

3. Synthesis example 3
Under a nitrogen gas atmosphere, 53.05 g (165.66 mmol) of TFMB and 67.91 g of DMAc were added to a 1 L separable flask equipped with a stirring wing, and TFMB was dissolved in DMAc while stirring at room temperature. Next, 22.11 g (49.77 mmol) of 6FDA, 4.88 g (16.59 mmol) of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride (BPDA) were added to the flask, and then TPC20 .21 g (99.54 mmol) was added and stirred at room temperature for 1 hour. Next, 10.53 g (133.08 mmol) of pyridine and 13.77 g (134.83 mmol) of acetic anhydride were added to the flask, stirred at room temperature for 30 minutes, then heated to 70 ° C. using an oil bath, and further 3 hours Stir to obtain a reaction solution.
The resulting reaction solution was cooled to room temperature, charged into a large amount of methanol in a thread form, and the deposited precipitate was taken out, immersed in methanol for 6 hours, and then washed with methanol. Next, the precipitate was dried under reduced pressure at 100 ° C. to obtain polyamideimide. The weight average molecular weight (Mw) of the polyamideimide was 190,000.

4. Synthesis example 4
In a nitrogen atmosphere, 1.25 g of isoquinoline was charged into a reaction vessel connected to a vacuum pump equipped with a solvent trap and a filter. Next, 375.00 g of GBL and 104.12 g of TFMB were charged into a reaction vessel, and the mixture was stirred and dissolved. Further, 145.88 g of 6FDA was added to the reaction vessel, and then the temperature was raised with an oil bath while stirring the mixture. The molar ratio of TFMB to 6FDA added was 1.00: 0.99, and the monomer concentration in the mixture was 40% by mass. When the internal temperature of the reaction vessel reached 80 ° C., the pressure was reduced to 650 mmHg, and then the internal temperature was raised to 180 ° C. After the internal temperature reached 180 ° C., heating and stirring were further performed for 4 hours. Thereafter, the pressure was restored to atmospheric pressure, and the internal temperature was cooled to 155 ° C. to obtain a polyimide solution. GBL was added at 155 ° C. to prepare a uniform solution having a polyimide solid content of 24% by mass, and then the polyimide varnish (1) as a uniform solution was taken out of the reaction vessel. When the GPC measurement was performed about the polyimide in the obtained polyimide varnish, the weight average molecular weight (Mw) was 360,000.

(Optical film)
1. Examples 1-4
The polyamide imide resin (TPC / 6FDA / OBBC / TFMB = 50/30/20/100) obtained in Synthesis Example 1 was diluted with GBL, and GBL substituted silica sol was added and thoroughly mixed, as described in Table 1. A resin / silica particle mixed varnish having the following composition was obtained. In that case, the mixing varnish was prepared so that the density | concentration of resin and a silica particle might be 8.0-15.0 mass%. After filtering the obtained polyamideimide varnish with a filter of 10 μm mesh, apply an applicator so that the film thickness of the self-supporting film becomes 55 μm on the smooth surface of the polyester base material (manufactured by Toyobo Co., Ltd., trade name “A4100”) After coating at 50 ° C. for 30 minutes and then at 140 ° C. for 15 minutes, the resulting coating film was peeled from the polyester substrate to obtain a self-supporting film. The self-supporting film was fixed to a metal frame, and further dried in the atmosphere at 200 ° C. for 40 minutes to obtain a polyamideimide film (optical film) having a thickness of 50 μm.

2. Examples 5 to 8 and Comparative Example 1
Except that the polyamideimide resin (TPC / 6FDA / OBBC / TFMB = 50/30/20/100) obtained in Synthesis Example 2 was changed to TPC / 6FDA / OBBC / TFMB = 60/30/10/10/100. As in Examples 1 to 4, polyamideimide films (optical films) containing silica particles were obtained.

3. Example 9
Example 2 is the same as Example 2 except that the polyamideimide resin obtained in Synthesis Example 1 is changed to the polyamideimide resin obtained in Synthesis Example 3 (TPC / 6FDA / BPDA / TFMB = 60/30/10/100). Similarly, a polyamideimide film (optical film) having a thickness of 50 μm was obtained.

4. Example 10
A polyamideimide film (optical film) having a thickness of 50 μm was obtained in the same manner as in Example 6 except that the average primary particle diameter of the silica particles was changed to 20 nm.

5. Example 11
Polyamide having a thickness of 50 μm as in Example 5 except that the content R _Si of the silica particles relative to the polyamide-imide film (optical film) is 10 mass% and the average primary particle diameter of the silica particles is changed to 83 nm. An imide film (optical film) was obtained.

6. Comparative example 2
The polyamideimide varnish having a concentration of 22% by mass was prepared by diluting the polyamideimide resin (TPC / 6FDA / BPDA / TFMB = 60/30/10/100) obtained in Synthesis Example 3 with DMAc. After filtering the obtained polyamideimide varnish with a filter of 10 μm mesh, apply an applicator so that the film thickness of the self-supporting film becomes 55 μm on the smooth surface of the polyester base material (manufactured by Toyobo Co., Ltd., trade name “A4100”) After coating at 50 ° C. for 30 minutes and then at 140 ° C. for 15 minutes, the resulting coating film was peeled from the polyester substrate to obtain a self-supporting film. The self-supporting film was fixed to a metal frame, and further dried in the atmosphere at 200 ° C. for 40 minutes to obtain a polyamideimide film (optical film) having a thickness of 50 μm.

7). Comparative example 3
The polyimide resin (6FDA / TFMB = 100/100) obtained in Synthesis Example 4 was diluted at a GBL / DMAc = 10/90 ratio to prepare a polyimide varnish having a concentration of 15.7% by mass. After filtering the obtained polyimide varnish with a filter of 10 μm openings, apply an applicator to a smooth surface of a polyester substrate (Toyobo Co., Ltd., trade name “A4100”) so that the thickness of the self-supporting film becomes 55 μm. After coating at 50 ° C. for 30 minutes and then at 140 ° C. for 15 minutes, the resulting coating film was peeled from the polyester substrate to obtain a self-supporting film. The self-supporting film was fixed to a metal frame and further dried at 200 ° C. for 40 minutes in the air to obtain a polyimide film (optical film) having a thickness of 50 μm.

8. Comparative example 4
The polyimide resin (6FDA / TFMB = 100/100) obtained in Synthesis Example 4 was diluted with GBL, and a GBL-substituted silica sol was added and mixed well to obtain a resin / silica particle mixed varnish. At that time, a mixed varnish was prepared so that the concentration of the resin and the silica particles would be 15.0% by mass. After filtering the obtained polyimide varnish with a filter of 10 μm openings, apply an applicator to a smooth surface of a polyester substrate (Toyobo Co., Ltd., trade name “A4100”) so that the thickness of the self-supporting film becomes 55 μm. After coating at 50 ° C. for 30 minutes and then at 140 ° C. for 15 minutes, the resulting coating film was peeled from the polyester substrate to obtain a self-supporting film. The self-supporting film was fixed to a metal frame and further dried at 200 ° C. for 40 minutes in the air to obtain a polyimide film (optical film) having a thickness of 50 μm.

  Table 1 shows the evaluation results of ΔHz at room temperature, ΔHz at a temperature of 85 ° C. and a relative humidity of 85%, and a bending resistance test of the optical films obtained in Examples 1 to 11 and Comparative Examples 1 to 4. In Table 1, the ratio of the structural units constituting the polyamideimide resin is the structural unit derived from TPC-derived structural unit / 6FDA-derived structural unit / OBBC for Examples 1 to 8, 10, 11 and Comparative Example 1. The ratio (mol%) of the constituent unit derived from unit / TFMB is shown, and for Example 9 and Comparative Example 2, the constituent unit derived from TPC / 6 the constituent unit derived from FDA / the constituent unit derived from BPDA / the constituent unit derived from TFMB The ratio (mol%) is expressed, and in Comparative Examples 3 and 4, the ratio (mol%) of the structural unit derived from 6FDA / the structural unit derived from TFMB is expressed.

  The optical films of Examples 1 to 11 all have a flex resistance of 10,000 times or more in the flex resistance test, are excellent in flex resistance, and have a temperature of 85 ° C. compared to the optical films of Comparative Examples 1 to 4. • It was confirmed that ΔHz at storage at 85% relative humidity was remarkably low. Therefore, the optical films of Examples 1 to 11 can achieve both excellent bending resistance and excellent stability of optical characteristics under high temperature and high humidity.

Claims (5)

An optical film comprising a polyamideimide resin and silica particles having an average primary particle diameter of 100 nm or less ,
Formula (1)
ΔHz <0.5 (1)
[In the formula (1), ΔHz represents Hz _a -Hz _b , and Hz _a is bent at a bending radius of 1 mm at room temperature and bent once to return to a flat shape (according to JIS K 5600-5-1: 1999). Represents the haze (%) of the optical film and the Hz _b represents the haze (%) of the optical film before the mandrel test]
The polyamideimide resin is a resin including a structural unit derived from a dicarboxylic acid compound, a structural unit derived from a tetracarboxylic acid compound, and a structural unit derived from a diamine compound, and the structural unit derived from the dicarboxylic acid compound is , Formula (I)

[In Formula (I), R ¹ and R ² each independently represent a hydroxyl group, a methoxy group, an ethoxy group, an n-propoxy group, an n-butoxy group or a chlorine atom, and R ^{3 to} R ⁶ each independently represent Represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an aryl group having 6 to 12 carbon atoms, and the hydrogen atoms contained in R ^{3 to} R ⁶ may be each independently substituted with a halogen atom.
An optical film containing a structural unit derived from the compound represented by formula (1), wherein the content of the silica particles is from 5 to 50% by mass relative to the mass of the optical film, and the thickness of the optical film is from 20 to 100 μm. The optical film according to claim 1, wherein Hz _b in the formula (1) is 1.0% or less. The average primary particle diameter of the silica particles is 80nm or less, the optical film according to claim 1 or 2. The structural unit derived from the tetracarboxylic acid compound constituting the polyamideimide resin has the formula (II)

[In Formula ^(II), the R 7 ^{to R 14} are each independently a hydrogen atom, an alkyl group or an aryl group having 6 to 12 carbon atoms having 1 to 6 carbon ^atoms, hydrogen atoms contained in R 7 ^{to R 14} Each may be independently substituted with a halogen atom]
And a constituent unit derived from a diamine compound constituting the polyamideimide resin and having a constituent unit derived from a compound represented by formula (III):

Wherein ^{(III), R} 15 ~R ²² independently represent a hydrogen atom, an alkyl group or an aryl group having 6 to 12 carbon atoms having 1 to 6 carbon ^atoms, hydrogen contained in R 15 ^{to R 22} Each atom may be independently substituted with a halogen atom]
The optical film in any one of Claims 1-3 containing the structural unit derived from the compound represented by these. The structural unit derived from the dicarboxylic acid compound constituting the polyamideimide resin has the formula (IV)

[In formula (IV), R ²³ and R ²⁴ each independently represent a hydroxyl group, a methoxy group, an ethoxy group, an n-propoxy group, an n-butoxy group or a chlorine atom, and R ^{25 to} R ³² each represent Independently, it represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an aryl group having 6 to 12 carbon atoms, and the hydrogen atoms contained in R ^{25 to} R ³² may be each independently substituted by a halogen atom well, a is _{independently, -O -, - CH 2 -} , - CH 2 -CH 2 -, - CH (CH 3) -, - C (CH 3) 2 -, - C (CF 3) 2 —, —SO ₂ —, —S—, —CO— or —NR ³³ —, wherein R ³³ represents a hydrocarbon group having 1 to 12 carbon atoms which may be substituted with a halogen atom; Represents an integer of 4]
The optical film in any one of Claims 1-4 containing the structural unit derived from the compound represented by these.