JP6568290B1 - Optical film - Google Patents

Abstract

An optical film having excellent impact resistance is provided. An optical film comprising at least one resin selected from the group consisting of a polyimide resin and a polyamide resin, and a filler having a primary particle diameter of 25 nm or less. [Selection figure] None

Description

  The present invention relates to an optical film used as a front plate or the like of an image display device, and a flexible image display device including the optical film.

  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, for example. As one of materials that can replace glass, there are polyimide resins and polyamide resins, and optical films using these resins have been studied (for example, Patent Document 1).

JP-T-2015-521687

  On the other hand, the front plate of such an image display device may cause scratches such as dents or damage on the front plate due to direct contact by the user or direct contact with surrounding objects. The optical film used is required to have impact resistance. However, according to the study of the present inventor, it has been found that an optical film containing a polyimide resin or a polyamide resin may not have sufficient impact resistance.

  Therefore, the objective of this invention is providing the flexible image display apparatus provided with the optical film excellent in impact resistance, and this optical film.

  As a result of intensive studies to solve the above problems, the present inventor has at least one resin selected from the group consisting of a polyimide resin and a polyamide resin, and a primary particle diameter of 25 nm or less. It has been found that the above object can be achieved when the filler or the filler having an average circle equivalent radius of 12 nm or less obtained from the analysis of the SEM image is achieved, and the present invention has been completed. That is, the present invention includes the following aspects.

［式（１３）中、Ｇ^３及びＡ^３は、それぞれ独立に、２価の有機基である］
で表される繰り返し構造単位を含む、［１］〜［４］のいずれかに記載の光学フィルム。
［６］前記樹脂は、式（１０）

［式（１０）中、Ｇは４価の有機基であり、Ａは２価の有機基である］
で表される繰り返し構造単位をさらに含む、［５］に記載の光学フィルム。
［７］ヘイズは１％以下である、［１］〜［６］のいずれかに記載の光学フィルム。
［８］黄色度は５以下である、［１］〜［７］のいずれかに記載の光学フィルム。
［９］フィラーはシリカ粒子である、［１］〜［８］のいずれかに記載の光学フィルム。
［１０］フィラーの含有量は、光学フィルムの質量に対して６０質量％以下である、［１］〜［９］のいずれかに記載の光学フィルム。
［１１］膜厚は２５〜１００μｍである、［１］〜［１０］のいずれかに記載の光学フィルム。
［１２］［１］〜［１１］のいずれかに記載の光学フィルムを備える、フレキシブル画像表示装置。
［１３］さらに偏光板を含有する、［１２］に記載のフレキシブル画像表示装置。
［１４］さらにタッチセンサを含有する、［１２］又は［１３］に記載のフレキシブル画像表示装置。 [1] An optical film comprising at least one resin selected from the group consisting of a polyimide resin and a polyamide resin, and a filler having a primary particle diameter of 25 nm or less.
[2] The optical film according to [1], wherein a primary particle size of the filler is 1 nm or more.
[3] An optical film comprising at least one resin selected from the group consisting of a polyimide resin and a polyamide resin, and a filler having an average equivalent circle radius obtained from an analysis of an SEM image of 12 nm or less. .
[4] The optical film according to [3], wherein the equivalent circle radius of the filler is 1 nm or more.
[5] The resin has the formula (13)

[In Formula (13), G ³ and A ³ are each independently a divalent organic group]
The optical film in any one of [1]-[4] containing the repeating structural unit represented by these.
[6] The resin has the formula (10)

[In Formula (10), G is a tetravalent organic group, and A is a divalent organic group]
The optical film according to [5], further comprising a repeating structural unit represented by:
[7] The optical film according to any one of [1] to [6], wherein the haze is 1% or less.
[8] The optical film according to any one of [1] to [7], wherein the yellowness is 5 or less.
[9] The optical film according to any one of [1] to [8], wherein the filler is silica particles.
[10] The optical film according to any one of [1] to [9], wherein the filler content is 60% by mass or less based on the mass of the optical film.
[11] The optical film according to any one of [1] to [10], wherein the film thickness is 25 to 100 μm.
[12] A flexible image display device comprising the optical film according to any one of [1] to [11].
[13] The flexible image display device according to [12], further including a polarizing plate.
[14] The flexible image display device according to [12] or [13], further including a touch sensor.

  Since the optical film of the present invention is excellent in impact resistance, it can be used as a front plate material for an image display device.

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

  The optical film of the present invention includes at least one resin selected from the group consisting of a polyimide resin and a polyamide resin, and a filler having a primary particle diameter of 25 nm or less.

<Resin>
The optical film of the present invention contains at least one resin selected from the group consisting of polyimide resins and polyamide resins. The polyimide resin is a polymer comprising a repeating structural unit containing an imide group, and a polymer containing a repeating structural unit containing both an imide group and an amide group (sometimes referred to as polyamideimide). 1 shows at least one polymer selected. The polyamide-based resin refers to a polymer containing a repeating structural unit containing an amide group. In the present specification, the repeating structural unit may be referred to as a structural unit.

The polyimide resin preferably has a repeating structural unit represented by the formula (10). Here, G is a tetravalent organic group, and A is a divalent organic group. The polyimide resin may contain a repeating structural unit represented by two or more types of formula (10) in which G and / or A are different.

  The polyimide resin contains one or more selected from the group consisting of repeating structural units represented by formula (11), formula (12), and formula (13) as long as various physical properties of the optical film are not impaired. Also good.

In formula (10) and formula (11), G and G ¹ are each independently a tetravalent organic group, preferably an organic group that may be substituted with a hydrocarbon group or a fluorine-substituted hydrocarbon group. It is a group. The G and ^{G 1,} equation (20), equation (21), equation (22), equation (23), equation (24), equation (25), equation (26), equation (27), formula (28 ) Or a group represented by formula (29) and a tetravalent hydrocarbon group having 6 or less carbon atoms. Since it is easy to suppress the yellowness (YI value) of the optical film, among them, the formula (20), formula (21), formula (22), formula (23), formula (24), formula (25), formula The group represented by (26) or formula (27) is preferred.

In formula (20), formula (21), formula (22), formula (23), formula (24), formula (25), formula (26), formula (27), formula (28) and formula (29) ,
* Represents a bond,
Z is a single _{bond, -O -, - CH 2 -} , - CH 2 -CH 2 -, - CH (CH 3) -, - C (CH 3) 2 -, - C (CF 3) 2 -, - _{Ar -, - SO 2 -,} - CO -, - O-Ar-O -, - Ar-O-Ar -, - Ar-CH 2 -Ar -, - Ar-C (CH 3) 2 -Ar- , or It represents a _-Ar-SO 2 -Ar-. Ar represents an arylene group having 6 to 20 carbon atoms which may be substituted with a fluorine atom, and specific examples thereof include a phenylene group.

In formula (12), G ² is a trivalent organic group, preferably an organic group which may be substituted with a hydrocarbon group or a fluorine-substituted hydrocarbon group. The G ^2, equation (20), equation (21), equation (22), equation (23), equation (24), equation (25), equation (26), equation (27), equation (28) or Examples thereof include a group in which any one of the bonds of the group represented by formula (29) is replaced with a hydrogen atom, and a trivalent chain hydrocarbon group having 6 or less carbon atoms.

In Formula (13), G ³ is a divalent organic group, preferably an organic group that may be substituted with a hydrocarbon group or a fluorine-substituted hydrocarbon group. The G ^3, equation (20), equation (21), equation (22), equation (23), equation (24), equation (25), equation (26), equation (27), equation (28) or Examples of the bond of the group represented by formula (29) include a group in which two that are not adjacent to each other are replaced with hydrogen atoms, and a chain hydrocarbon group having 6 or less carbon atoms.

In formula (10) to formula (13), A, A ¹ , A ² and A ³ are each independently a divalent organic group, preferably substituted with a hydrocarbon group or a fluorine-substituted hydrocarbon group. An organic group that may be used. As A, A ¹ , A ² and A ³ , Formula (30), Formula (31), Formula (32), Formula (33), Formula (34), Formula (35), Formula (36), Formula ( 37) or a group represented by formula (38); a group in which they are substituted with a methyl group, a fluoro group, a chloro group or a trifluoromethyl group; and a chain hydrocarbon group having 6 or less carbon atoms.

In Formula (30), Formula (31), Formula (32), Formula (33), Formula (34), Formula (35), Formula (36), Formula (37), and Formula (38),
* Represents a bond,
Z ^{1, Z 2} and ^{Z 3} are independently a single _{bond, -O -, - CH 2 -} , - CH 2 -CH 2 -, - CH (CH 3) -, - C (CH 3) 2 - _{, -C (CF 3) 2 -} , - representing the or -CO- - SO _2.
One example is when Z ¹ and Z ³ are —O— and Z ² is —CH ₂ —, —C (CH ₃ ) ₂ —, —C (CF ₃ ) ₂ — or —SO ₂ —. is there. The bonding position of each of Z ¹ and Z ² with respect to each ring and the bonding position of each of Z ² and Z ³ with respect to each ring is preferably a meta position or a para position, and more preferably a para position with respect to each ring. is there.

  In one embodiment of the present invention, the polyimide-based resin is a polyamide having at least a repeating structural unit represented by the formula (10) and a repeating structural unit represented by the formula (13) from the viewpoint of easily improving impact resistance. An imide is preferred. Moreover, it is preferable that a polyamide-type resin has at least the repeating structural unit represented by Formula (13).

  In one embodiment of the present invention, at least one resin selected from the group consisting of a polyimide resin and a polyamide resin includes a repeating structural unit represented by formula (13) from the viewpoint of impact resistance. It is more preferable that it contains a repeating structural unit represented by the formula (13) and a repeating structural unit represented by the formula (10).

［式（３）中、Ｒ^１〜Ｒ^８は、それぞれ独立に、水素原子、炭素数１〜６のアルキル基又は炭素数６〜１２のアリール基を表し、Ｒ^１〜Ｒ^８に含まれる水素原子は、それぞれ独立に、ハロゲン原子で置換されていてもよく、
Ｂは、単結合、−Ｏ−、−ＣＨ_２−、−ＣＨ_２−ＣＨ_２−、−ＣＨ（ＣＨ_３）−、−Ｃ（ＣＨ_３）_２−、−Ｃ（ＣＦ_３）_２−、−ＳＯ_２−、−Ｓ−、−ＣＯ−又は−Ｎ（Ｒ^９）−を表し、Ｒ^９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、
ｎは０〜４の整数であり、
＊は結合手を表す］
で表される構成単位であることが好ましい。 In one embodiment of the present invention, the resin may contain multiple types of G ³ , and the multiple types of G ³ may be the same or different from each other. In particular, from the viewpoint of improving the surface hardness, impact resistance, and flex resistance of the obtained optical film, at least a part of G ³ is represented by formula (3).

[In Formula (3), R ^{1 to} R ⁸ each independently represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an aryl group having 6 to 12 carbon atoms, and hydrogen contained in R ^{1 to} R ^8. Each atom may be independently substituted with a halogen atom,
B represents a single _{bond, -O -, - CH 2 -} , - CH 2 -CH 2 -, - CH (CH 3) -, - C (CH 3) 2 -, - C (CF 3) 2 -, - SO ₂ —, —S—, —CO— or —N (R ⁹ ) — is represented, and R ⁹ represents a hydrogen atom, a hydrocarbon group having 1 to 12 carbon atoms which may be substituted with a halogen atom,
n is an integer from 0 to 4,
* Represents a bond]
It is preferable that it is a structural unit represented by these.

In the formula (3), B is independently a single _{bond, -O -, - CH 2 -} , - CH 2 -CH 2 -, - CH (CH 3) -, - C (CH 3) 2 -, —C (CF ₃ ) ₂ —, —SO ₂ —, —S—, —CO— or —N (R ⁹ ) —, and preferably from the viewpoint of improving the impact resistance and flex resistance of the optical film, O- or -S- is represented, more preferably -O-. R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ and R ⁸ are each independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 12 carbon atoms. Represent. 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. Moreover, as a C6-C12 aryl group, a phenyl group, a tolyl group, a xylyl group, a naphthyl group, a biphenyl group etc. are mentioned, for example. From the viewpoint of the surface hardness, impact resistance, and flexibility of the optical film, R ^{1 to} R ⁸ each independently preferably represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and more preferably a hydrogen atom or A C1-C3 alkyl group is represented, More preferably, a hydrogen atom is represented. Here, the hydrogen atoms contained in R ^{1 to} R ⁸ may be each independently substituted with a halogen atom.
R ⁹ represents a hydrocarbon group having 1 to 12 carbon atoms which may be substituted with a hydrogen atom or a halogen atom. R ⁹ represents a hydrogen atom or a monovalent hydrocarbon group having 1 to 12 carbon atoms which may be substituted with a halogen atom. Examples of the monovalent hydrocarbon group having 1 to 12 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-butyl group, 3-methylbutyl group, 2-ethyl-propyl group, n-hexyl, n-heptyl group, n-octyl group, tert-octyl group, n-nonyl group, n-decyl group, etc. These may be substituted with a halogen atom. Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

In Formula (3), n is an integer in the range of 0 to 4, and when n is within this range, the impact resistance, flex resistance and elastic modulus of the optical film are good. In Formula (3), n is preferably an integer in the range of 0 to 3, more preferably an integer in the range of 0 to 2, further preferably 0 or 1, and n is within this range. The impact resistance, flex resistance and elastic modulus of the optical film are good, and at the same time, the availability of raw materials is relatively good. G ³ may contain one or more structural units represented by the formula (3), and improves the impact resistance, elastic modulus and flex resistance of the optical film, and the yellowness (YI From the viewpoint of (value) reduction, two or more types of structural units having different values of n, particularly, two types of structural units having different values of n may be included. In that case, it is preferable that n contains both the structural unit whose n is 0 and 1 from a viewpoint which an optical film tends to express a high elasticity modulus, impact resistance, bending resistance, and low yellowness (YI value).

で表される構成単位であり、これらは併用することもできる。この場合、光学フィルムは、高い表面硬度及び耐衝撃性を発揮すると同時に、高い耐屈曲性を有することができ、黄色度を低くすることができる。 In a preferred embodiment of the present invention, the formula (3) is a structural unit in which n = 0, R ^{1 to} R ⁸ are hydrogen atoms, or the formula (3 ′):

These units can be used in combination. In this case, the optical film can exhibit high surface hardness and impact resistance, and at the same time can have high bending resistance, and can reduce yellowness.

  In a preferred embodiment of the present invention, the formula in the case where n is 0 to 4 with respect to the total of the structural unit represented by the formula (10) and the structural unit represented by the formula (13) of the polyimide resin. The structural unit represented by (3) is preferably at least 20 mol%, more preferably at least 30 mol%, even more preferably at least 40 mol%, particularly preferably at least 50 mol%, most preferably at least 60 mol%. Yes, preferably 90 mol% or less, more preferably 85 mol% or less, still more preferably 80 mol% or less. The structure represented by Formula (3) when n is 0 to 4 with respect to the total of the structural unit represented by Formula (10) and the structural unit represented by Formula (13) in the polyimide resin. When the unit is at least the above lower limit, the optical film can exhibit high surface hardness and impact resistance, and can be excellent in flex resistance and elastic modulus. The structure represented by Formula (3) when n is 0 to 4 with respect to the total of the structural unit represented by Formula (10) and the structural unit represented by Formula (13) in the polyimide resin. When the unit is not more than the above upper limit, the viscosity of the polyimide resin varnish can be suppressed by suppressing the thickening due to the hydrogen bond between the amide bonds derived from the formula (3), and the processing of the optical film is easy. can do.

In a preferred embodiment of the present invention, n in the formula (3) is 1 to 4 with respect to the total of the structural unit represented by the formula (10) and the structural unit represented by the formula (13) of the polyimide resin. The ratio of structural units represented by is preferably 3 mol% or more, more preferably 5 mol% or more, still more preferably 7 mol% or more, particularly preferably 9 mol% or more, preferably 90 mol% or less, More preferably, it is 70 mol% or less, More preferably, it is 50 mol% or less, Most preferably, it is 30 mol% or less. The ratio of the structural unit represented by n in Formula (3) to 1 to 4 with respect to the total of the structural unit represented by Formula (10) and the structural unit represented by Formula (13) in the polyimide resin. Is equal to or more than the above lower limit, the optical film can exhibit high surface hardness and impact resistance, and the flex resistance is further improved. The ratio of the structural unit represented by n in Formula (3) to 1 to 4 with respect to the total of the structural unit represented by Formula (10) and the structural unit represented by Formula (13) in the polyimide resin. Is less than the above upper limit, the viscosity of the polyimide resin varnish can be suppressed by suppressing the increase in viscosity due to the hydrogen bond between the amide bonds derived from the formula (3), and the processing of the optical film is facilitated. be able to. The content of the structural unit represented by the formula (3) can also be calculated from, for example, ^{1 H-NMR} can be measured using, or the material feed ratio.

In a preferred embodiment of the present invention, G ³ of the polyimide resin is preferably 5 mol% or more, more preferably 8 mol% or more, further preferably 10 mol% or more, particularly preferably 12 mol% or more. It represents with Formula (3) in case n is 1-4. Or above the lower limit of G ³ of polyimide resin is, at the same time n is represented by the formula (3) in the case 1 to 4, the optical film when expressed high surface hardness and impact resistance, high flexural Can have sex. Further, G ³ in the polyimide-based resin is preferably 90 mol% or less, more preferably 70 mol% or less, further preferably 50 mol% or less, particularly preferably 30 mol% or less, and n is 1 to 4. The case is preferably represented by the formula (3). When the above upper limit of G ³ of the polyimide-based resin is represented by the formula (3) when n is 1 to 4, the viscosity increase due to the hydrogen bond between amide bonds derived from the formula (3) is suppressed. The viscosity of the resin varnish can be suppressed, and the optical film can be easily processed.

In a preferred embodiment of the present invention, G ³ in the polyimide-based resin is preferably 30 mol% or more, more preferably 50 mol% or more, particularly preferably 70 mol% or more, and n is 0 to 4. The case is represented by Equation (3). At the same time more than the above lower limit of G ³ of polyimide resin is, when n is represented by the formula (3) when it is 0-4, the optical film when expressed high surface hardness and impact resistance, high resistance to It can have flexibility. Further, the ^{G 3} in the polyimide-based resin, preferably 100 mol% or less, n is is preferably represented by the formula (3) when it is 0-4. When the above upper limit value of G ³ of the polyimide-based resin is expressed by the formula (3) when n is 0 to 4, the increase in viscosity due to the hydrogen bond between amide bonds derived from the formula (3) is suppressed. Thereby, the viscosity of a resin varnish can be suppressed and the process of an optical film can be made easy. Incidentally, in the polyimide resin, the ratio of structural units represented by the formula (3) can also be calculated from, for example, ^{1 H-NMR} can be measured using, or the material feed ratio.

［式（４）中、Ｒ^１０〜Ｒ^１７は、それぞれ独立に、水素原子、炭素数１〜６のアルキル基又は炭素数６〜１２のアリール基を表し、Ｒ^１０〜Ｒ^１７に含まれる水素原子は、それぞれ独立に、ハロゲン原子で置換されていてもよく、＊は結合手を表す］
で表される構成単位である。式（１０）及び式（１３）中の複数のＡ及びＡ^３の少なくとも一部が式（４）で表される基であると、光学フィルムは、高い表面硬度及び耐衝撃性を発現できると同時に、高い透明性を有することができる。 In a preferred embodiment of the present invention, at least some of the plurality of A and A ³ in formula (10) and formula (13) are represented by formula (4):

Wherein ^{(4), R} 10 ~R ¹⁷ 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 10 ^{to R 17} Each atom may be independently substituted with a halogen atom, and * represents a bond]
It is a structural unit represented by When at least a part of the plurality of A and A ³ in Formula (10) and Formula (13) is a group represented by Formula (4), the optical film can exhibit high surface hardness and impact resistance. At the same time, it can have high transparency.

In Formula (4), R ¹⁰ , R ¹¹ , R ¹² , R ¹³ , R ¹⁴ , R ¹⁵ , R ¹⁶ and R ¹⁷ are each independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or 6 carbon atoms. Represents an aryl group of ˜12. Examples of the alkyl group having 1 to 6 carbon atoms or the aryl group having 6 to 12 carbon atoms include those exemplified as the alkyl group having 1 to 6 carbon atoms or the aryl group having 6 to 12 carbon atoms in the formula (3). R ^{10 to} R ¹⁷ each independently preferably represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, more preferably a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, where R ¹⁰ to R ¹⁰ Each hydrogen atom contained in R ¹⁷ may be independently substituted with a halogen atom. Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. R ^{10 to} R ¹⁷ are each independently more preferably a hydrogen atom, a methyl group, a fluoro group, a chloro group, or a trifluoromethyl group from the viewpoint of the surface hardness, impact resistance, transparency, and flex resistance of the optical film. And particularly preferably R ¹⁰ , R ¹² , R ¹³ , R ¹⁴ , R ¹⁵ , and R ¹⁶ are hydrogen atoms, R ¹¹ and R ¹⁷ are hydrogen atoms, methyl groups, fluoro groups, chloro groups, or trifluoromethyl groups. In particular, R ¹¹ and R ¹⁷ are preferably a methyl group or a trifluoromethyl group.

で表される構成単位であり、すなわち、複数のＡ及びＡ^３の少なくとも一部は、式（４’）で表される構成単位である。この場合、光学フィルムは、高い透明性を発現すると同時に、フッ素元素を含有する骨格により該樹脂の溶媒への溶解性を向上し、樹脂ワニスの粘度を低く抑制することができ、光学フィルムの加工を容易にすることができる。 In a preferred embodiment of the present invention, the structural unit represented by the formula (4) is represented by the formula (4 ′):

That is, at least some of the plurality of A and A ³ are structural units represented by the formula (4 ′). In this case, the optical film exhibits high transparency, and at the same time, the skeleton containing the fluorine element can improve the solubility of the resin in the solvent, thereby suppressing the viscosity of the resin varnish, and processing the optical film. Can be made easier.

In a preferred embodiment of the present invention, A and A ^{3 in} the resin are preferably 30 mol% or more, more preferably 50 mol% or more, and even more preferably 70 mol% or more of the formula (4), particularly the formula ( 4 ′). When A and A ³ within the above-mentioned range in the resin are represented by the formula (4), particularly the formula (4 ′), the optical film exhibits high transparency and at the same time has a resin containing a fluorine element. The solubility of the resin varnish can be improved, the viscosity of the resin varnish can be suppressed to a low level, and the processing of the optical film can be facilitated. Incidentally, preferably, 100 mole percent of A and ^{A 3} in the resin following the expression (4), in particular represented by the formula (4 '). A and A ³ in the resin may be of the formula (4), in particular (4 ′). The ratio of the expression structure unit represented by formula (4) in the resin of the A and A ^3, for example, ^{1 H-NMR} can be measured using, or can be calculated from the charge ratio of the raw materials.

［式（５）中、Ｒ^１８〜Ｒ^２５は、それぞれ独立に、水素原子、炭素数１〜６のアルキル基又は炭素数６〜１２のアリール基を表し、Ｒ^１８〜Ｒ^２５に含まれる水素原子は、それぞれ独立に、ハロゲン原子で置換されていてもよく、＊は結合手を表す］
で表される構成単位である。式（１０）中の複数のＧの少なくとも一部が式（５）で表される基であると、光学フィルムは、高い透明性を発現すると同時に、ポリイミド系樹脂の溶媒への溶解性を向上し、樹脂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加工を容易にすることができる。 In a preferred embodiment of the present invention, at least some of the plurality of Gs in formula (10) are represented by formula (5):

Wherein ^{(5), R} 18 ~R ²⁵ 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 18 ^{to R 25} Each atom may be independently substituted with a halogen atom, and * represents a bond]
It is a structural unit represented by When at least a part of a plurality of G in the formula (10) is a group represented by the formula (5), the optical film exhibits high transparency and at the same time improves the solubility of the polyimide resin in the solvent. In addition, the viscosity of the resin varnish can be suppressed low, and the processing of the optical film can be facilitated.

In Formula (5), R ¹⁸ , R ¹⁹ , R ²⁰ , R ²¹ , R ²² , R ²³ , R ²⁴ and R ²⁵ are each independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or 6 carbon atoms. Represents an aryl group of ˜12. Examples of the alkyl group having 1 to 6 carbon atoms or the aryl group having 6 to 12 carbon atoms include those exemplified as the alkyl group having 1 to 6 carbon atoms or the aryl group having 6 to 12 carbon atoms in the formula (3). R ¹⁸ to R ²⁵ are each independently preferably represents an alkyl group having 1 to 6 carbon hydrogen atom or atoms, more preferably represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, ^{wherein, R 18} ~ Each hydrogen atom contained in R ²⁵ may be independently substituted with a halogen atom. Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. R ^{18 to} R ²⁵ are each independently more preferably a hydrogen atom, a methyl group, a fluoro group, a chloro group, or a trifluoromethyl group, from the viewpoint of easily improving the surface hardness, flex resistance, and transparency of the optical film. And more preferably R ¹⁸ , R ¹⁹ , R ²⁰ , R ²³ , R ²⁴ and R ²⁵ are hydrogen atoms, R ²¹ and R ²² are hydrogen atoms, methyl groups, fluoro groups, chloro groups or trifluoromethyl groups. In particular, R ²¹ and R ²² are preferably a methyl group or a trifluoromethyl group.

で表される構成単位であり、すなわち、複数のＧの少なくとも一部は、式（５’）で表される構成単位である。この場合、光学フィルムは、高い透明性を有することができる。 In a preferred embodiment of the present invention, the structural unit represented by the formula (5) is represented by the formula (5 ′):

That is, at least a part of the plurality of Gs is a structural unit represented by the formula (5 ′). In this case, the optical film can have high transparency.

In a preferred embodiment of the present invention, G in the polyimide-based resin is preferably 50 mol% or more, more preferably 60 mol% or more, and even more preferably 70 mol% or more of the formula (5), particularly the formula (5 ') When G within the above-mentioned range in the polyimide resin is represented by the formula (5), particularly the formula (5 ′), the optical film can have high transparency, and the polyimide is further contained by a skeleton containing a fluorine element. The solubility of the resin in the solvent can be improved, the viscosity of the resin varnish can be suppressed low, and the production of the optical film is easy. In addition, Preferably, 100 mol% or less of G in the said polyimide resin is represented by Formula (5), especially Formula (5 '). G in the polyimide resin may be the formula (5), particularly the formula (5 ′). The ratio of the structural unit represented by the formula (5) of G in the polyimide resin can be measured, for example, using ¹ H-NMR, or can be calculated from the raw material charge ratio.

  In one embodiment of the present invention, the polyimide resin comprises a diamine, a tetracarboxylic acid compound (an acid chloride compound, a tetracarboxylic acid analog such as tetracarboxylic dianhydride), and, if necessary, a dicarboxylic acid compound. It is a condensation polymer obtained by reacting (polycondensation) (dicarboxylic acid compound analogs such as acid chloride compounds), tricarboxylic acid compounds (tricarboxylic acid compound analogs such as acid chloride compounds and tricarboxylic acid anhydrides) and the like. . The repeating structural unit represented by formula (10) or formula (11) is usually derived from a diamine and a tetracarboxylic acid compound. The repeating structural unit represented by the formula (12) is usually derived from a diamine and a tricarboxylic acid compound. The repeating structural unit represented by the formula (13) is usually derived from a diamine and a dicarboxylic acid compound.

  In one embodiment of the present invention, the polyamide-based resin is a condensed polymer obtained by reacting (polycondensation) a diamine and a dicarboxylic acid compound. That is, the repeating structural unit represented by the formula (13) is usually derived from a diamine and a dicarboxylic acid compound.

  Examples of the tetracarboxylic acid compound include aromatic tetracarboxylic acid compounds such as aromatic tetracarboxylic dianhydrides; and aliphatic tetracarboxylic acid compounds such as aliphatic tetracarboxylic dianhydrides. A tetracarboxylic acid compound may be used independently and may use 2 or more types together. The tetracarboxylic acid compound may be a dianhydride or a tetracarboxylic acid compound analog such as an acid chloride compound.

  Specific examples of the aromatic tetracarboxylic dianhydride include 4,4′-oxydiphthalic dianhydride, 3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride, 2,2 ′, 3, 3'-benzophenonetetracarboxylic dianhydride, 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride (sometimes referred to as BPDA), 2,2', 3,3'-biphenyltetra Carboxylic dianhydride, 3,3 ′, 4,4′-diphenylsulfone tetracarboxylic 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 acid Product (6FDA), 1,2-bis (2,3-dicarboxyphenyl) ethane dianhydride, 1,1-bis (2,3-dicarboxyphenyl) ethane dianhydride, 1,2-bis (3 , 4-Dicarboxyphenyl) ethane dianhydride, 1,1-bis (3,4-dicarboxyphenyl) ethane dianhydride, bis (3,4-dicarboxyphenyl) methane dianhydride, bis (2, 3-dicarboxyphenyl) methane dianhydride and 4,4 ′-(p-phenylenedioxy) diphthalic dianhydride and 4,4 ′-(m-phenylenedioxy) diphthalic dianhydride (6FDA) Can be mentioned. 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 dianhydride, cycloalkanetetracarboxylic dianhydride such as 1,2,3,4-cyclopentanetetracarboxylic dianhydride, bicyclo [2.2 .2] Oct-7-ene-2,3,5,6-tetracarboxylic dianhydride, dicyclohexyl 3,3′-4,4′-tetracarboxylic dianhydride and their positional isomers. . These can be used alone or in combination of two or more. Specific examples of the acyclic aliphatic tetracarboxylic dianhydride include 1,2,3,4-butanetetracarboxylic dianhydride, 1,2,3,4-pentanetetracarboxylic dianhydride, and the like. These may be used alone or in combination of two or more. Further, a cycloaliphatic tetracarboxylic dianhydride and an acyclic aliphatic tetracarboxylic dianhydride may be used in combination.

  Among the above tetracarboxylic dianhydrides, 1,2,4,5-cyclohexanetetracarboxylic dianhydride, bicyclo [2.2.2] oct-7-ene are used from the viewpoint of high transparency and low colorability. -2,3,5,6-tetracarboxylic dianhydride and 4,4 '-(hexafluoroisopropylidene) diphthalic dianhydride, and mixtures thereof are preferred. Moreover, you may use the water adduct of the said tetracarboxylic acid compound anhydride as tetracarboxylic acid.

Examples of tricarboxylic acid compounds include aromatic tricarboxylic acids, aliphatic tricarboxylic acids, and related acid chloride compounds, acid anhydrides, and the like, and two or more of them may be used in combination.
Specific examples include 1,2,4-benzenetricarboxylic acid anhydride; 2,3,6-naphthalenetricarboxylic acid-2,3-anhydride; phthalic acid anhydride and benzoic acid are a single bond, —CH _{2 -, - C (CH 3)} 2 -, - C (CF 3) 2 -, - SO 2 - or a compound linked phenylene group.

Examples of dicarboxylic acid compounds include aromatic dicarboxylic acids, aliphatic dicarboxylic acids, and related acid chloride compounds, acid anhydrides, and the like, and two or more of them may be used in combination. Specific examples thereof include terephthalic acid dichloride; isophthalic acid dichloride; naphthalene dicarboxylic acid dichloride; 4,4′-biphenyldicarboxylic acid dichloride; 3,3′-biphenyldicarboxylic acid dichloride; 4,4′-oxybis (benzoyl chloride). (OBBC): a dicarboxylic acid compound of a chain hydrocarbon having 8 or less carbon atoms and two benzoic acids are a single bond, —CH ₂ —, —C (CH ₃ ) ₂ —, —C (CF ₃ ) ₂ —, Examples include compounds linked by —SO ₂ — or a phenylene group. Among these dicarboxylic acid compounds, terephthaloyl chloride and 4,4′-oxybis (benzoyl chloride) are more preferable. These dicarboxylic acids can be used alone or in combination of two or more.

  Examples of diamines 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, the aromatic ring is preferably a benzene ring. The “aliphatic diamine” refers to a diamine in which an amino group is directly bonded to an aliphatic group, and an aromatic ring or other substituent may be included in a part of the structure.

  Examples of the aliphatic diamine 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.

  Examples of the aromatic diamine include p-phenylenediamine, m-phenylenediamine, 2,4-toluenediamine, m-xylylenediamine, p-xylylenediamine, 1,5-diaminonaphthalene, and 2,6-diaminonaphthalene. An aromatic diamine having one aromatic ring, such as 4,4′-diaminodiphenylmethane, 4,4′-diaminodiphenylpropane, 4,4′-diaminodiphenyl ether, 3,4′-diaminodiphenyl ether, 3,3 ′ -Diaminodiphenyl ether, 4,4'-diaminodiphenyl sulfone, 3,4'-diaminodiphenyl sulfone, 3,3'-diaminodiphenyl sulfone, 1,4-bis (4-aminophenoxy) benzene, 1,3-bis ( 4-Aminophenoxy) benzene, 4,4'-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) benzidine (2,2′-bis (trifluoromethyl) -4 , 4′-diaminodiphenyl (TFMB)), 4,4′-bis (4-aminophenoxy) biphenyl, 4,4′-diaminodiphenyl ether, 3,4′-diaminodiphenyl ether, 4,4′-diaminodiphenylmethane, 9 , 9-bis (4-aminophenyl) fluorene, 9,9-bis (4-amino-3-methylphenyl) fluorene And aromatic diamines having two or more aromatic rings such as 9,9-bis (4-amino-3-chlorophenyl) fluorene and 9,9-bis (4-amino-3-fluorophenyl) fluorene. . These can be used alone or in combination of two or more.

  Among the diamines, from the viewpoint of high transparency and low colorability, it is preferable to use one or more selected from the group consisting of aromatic diamines having a biphenyl structure. One selected from the group consisting of 2,2′-dimethylbenzidine, 2,2′-bis (trifluoromethyl) benzidine, 4,4′-bis (4-aminophenoxy) biphenyl and 4,4′-diaminodiphenyl ether It is more preferable to use the above, and it is more preferable to use 2,2′-bis (trifluoromethyl) benzidine.

  The polyimide resin is prepared by mixing the raw materials such as the diamine, tetracarboxylic acid compound, tricarboxylic acid compound, and dicarboxylic acid compound by a conventional method, for example, a method such as stirring, and then converting the obtained intermediate into an imidization catalyst and If necessary, it can be obtained by imidization in the presence of a dehydrating agent. The polyamide-based resin can be obtained by mixing raw materials such as the diamine and dicarboxylic acid compound by a conventional method, for example, a method such as stirring.

  Although it does not specifically limit as an imidation catalyst used at an imidation process, For example, aliphatic amines, such as a tripropylamine, dibutylpropylamine, and ethyl dibutylamine; N-ethylpiperidine, N-propylpiperidine, N-butylpyrrolidine , N-butylpiperidine, and N-propylhexahydroazepine and other alicyclic amines (monocyclic); azabicyclo [2.2.1] heptane, azabicyclo [3.2.1] octane, azabicyclo [2.2 .2] Alicyclic amines (polycyclic) such as octane and azabicyclo [3.2.2] nonane; and 2-methylpyridine, 3-methylpyridine, 4-methylpyridine, 2-ethylpyridine, 3- Ethylpyridine, 4-ethylpyridine, 2,4-dimethylpyridine, 2,4,6-trimethylpyridine, 3 4 cyclopentenopyridine pyridine, 5,6,7,8-tetrahydroisoquinoline, and aromatic amines isoquinoline.

  The dehydrating agent used in the imidization step is not particularly limited, and examples thereof include acetic anhydride, propionic anhydride, isobutyric anhydride, pivalic anhydride, butyric anhydride, and isovaleric anhydride.

In the mixing and imidization step of each raw material, the reaction temperature is not particularly limited, but is, for example, 15 to 350 ° C, preferably 20 to 100 ° C. The reaction time is not particularly limited, but is, for example, about 10 minutes to 10 hours. If necessary, the reaction may be carried out under an inert atmosphere or under reduced pressure. The reaction may be performed in a solvent, and examples of the solvent include those exemplified as the solvent used for preparing the varnish. After the reaction, the polyimide resin or the polyamide resin is purified. Examples of the purification method include a method of adding a poor solvent to the reaction solution and precipitating the resin by a reprecipitation method, drying to take out the precipitate, and washing the precipitate with a solvent such as methanol as necessary to dry it. Can be mentioned.
For the production of the polyimide resin, for example, the production method described in JP-A-2006-199945 or JP-A-2008-163107 may be referred to. Commercially available products may also be used as the polyimide resin, and specific examples thereof include Neoprim (registered trademark) manufactured by Mitsubishi Gas Chemical Co., Ltd. and KPI-MX300F manufactured by Kawamura Sangyo Co., Ltd.

  The weight average molecular weight of the polyimide resin or polyamide resin is preferably 100,000 or more, more preferably 150,000 or more, further preferably 200,000 or more, even more preferably 250,000 or more, particularly preferably 300, 000 or more, preferably 600,000 or less, more preferably 500,000 or less. As the weight-average molecular weight of the polyimide resin or polyamide resin is larger, there is a tendency that high impact resistance and bending resistance when formed into a film are easily developed. Therefore, from the viewpoint of easily improving the impact resistance and flex resistance of the optical film, the weight average molecular weight is preferably not less than the above lower limit. On the other hand, the smaller the weight average molecular weight of the polyimide resin or polyamide resin, the easier it is to lower the viscosity of the varnish and the easier it is to improve processability. Moreover, there exists a tendency for the drawability of a polyimide-type resin or a polyamide-type resin to improve easily. Therefore, from the viewpoint of processability and stretchability, the weight average molecular weight is preferably not more than the above upper limit. In addition, in this application, a weight average molecular weight can perform a gel permeation chromatography (GPC) measurement, can be calculated | required by standard polystyrene conversion, for example, can be calculated by the method as described in an Example.

  The imidation ratio of the polyimide resin is preferably 95 to 100%, more preferably 97 to 100%, still more preferably 98 to 100%, and particularly preferably 100%. From the viewpoint of the stability of the varnish and the mechanical properties of the obtained optical film, it is preferable that the imidation ratio is in the above range. The imidization rate can be obtained by IR method, NMR method or the like.

  In a preferred embodiment of the present invention, the polyimide resin or polyamide resin contained in the optical film of the present invention contains a halogen atom such as a fluorine atom, which can be introduced by, for example, the above fluorine-containing substituent. Good. When the polyimide resin or polyamide resin contains a halogen atom, it is easy to improve the impact resistance and elastic modulus of the optical film and reduce the yellowness (YI value). When the impact resistance and elastic modulus of the optical film are high, it is easy to suppress the generation of scratches and wrinkles in the film, and when the optical film has a low yellowness, the transparency of the film is easily improved. The halogen atom is preferably a fluorine atom. Preferred fluorine-containing substituents for incorporating a fluorine atom into a polyimide resin or polyamide resin include, for example, a fluoro group and a trifluoromethyl group.

  The halogen atom content in the polyimide resin or polyamide resin is preferably 1 to 40% by mass, more preferably 5 to 40% by mass, and still more preferably 5 to 5%, based on the mass of the polyimide resin or polyamide resin. 30% by mass. When the halogen atom content is in the above range, the impact resistance and elastic modulus when formed into a film can be further improved, the water absorption can be lowered, and the yellowness (YI value) can be further reduced. Easy to improve. Moreover, there exists a tendency for the synthesis | combination of a polyimide resin or a polyamide-type resin to become easy.

  When the polyimide resin is polyamideimide, the content of the structural unit represented by the formula (13) is preferably 0.1 mol or more with respect to 1 mole of the structural unit represented by the formula (10). Preferably it is 0.5 mol or more, More preferably, it is 1.0 mol or more, Most preferably, it is 1.5 mol or more, Preferably it is 6.0 mol or less, More preferably, it is 5.0 mol or less, More preferably, it is 4. 5 mol or less. When the content of the structural unit represented by the formula (13) is equal to or higher than the lower limit, the optical film easily exhibits high surface hardness, impact resistance, and flex resistance. Moreover, when content of the structural unit represented by Formula (13) is below the said upper limit, the thickening by the hydrogen bond between the amide bonds in Formula (13) will be suppressed, and the viscosity of a resin varnish will be reduced. The optical film can be easily manufactured.

  In one embodiment of the present invention, the content of the polyimide resin and / or the polyamide resin in the optical film is preferably 40% by mass or more, more preferably 50% by mass or more, based on the total mass of the optical film. More preferably, it is 70 mass% or more. The content of the polyimide resin and / or the polyamide resin is preferably the above lower limit or more from the viewpoint of easily improving impact resistance, flex resistance, and the like. In addition, content of the polyimide-type resin and / or polyamide-type resin in an optical film is 100 mass% or less normally on the basis of the total mass of an optical film.

<Filler>
In one embodiment of the present invention, the optical film of the present invention contains a filler having a primary particle diameter of 25 nm or less. In another embodiment of the present invention, the optical film of the present invention contains a filler having an average equivalent circle radius obtained from the analysis of SEM images of 12 nm or less. The optical film of the present invention is excellent in that, in addition to the resin, a filler having a primary particle diameter of 25 nm or less, or a filler having an average circle equivalent radius obtained from analysis of an SEM image of 12 nm or less. Impact resistance can be expressed. In this specification, the impact resistance refers to a characteristic that can suppress the occurrence of scratches such as dents when an object collides with the optical film surface, or a characteristic that can suppress a change in shape of the surface. In the impact resistance test, the characteristic that the dent amount can be further reduced is shown.

  The average value of the circle-equivalent radius of the filler is an average value of values converted into the radius of a perfect circle having an area equal to the area of the filler primary particles obtained by analysis of an SEM (scanning electron microscope) image. The equivalent circle radius of the filler (filler primary particles) can be determined, for example, by the procedure described below. A smoothing process and shading correction are performed on the photographed electron microscope image as necessary, and then a binarization process is performed to obtain a binarized image. The binarized image is divided into particles using the Watershed method. A circle-equivalent radius distribution can be obtained by performing particle analysis on the binarized image after particle division. For particle analysis, general-purpose image analysis software such as ImageJ can be used. From the obtained circle equivalent radius distribution, the average value of the circle equivalent radii is obtained. For example, the average value of the equivalent circle radii of the filler can be obtained by the method described in the examples.

  Examples of the filler include organic particles and inorganic particles, and inorganic particles are particularly preferable. Inorganic particles include silica, zirconia, alumina, titania, zinc oxide, germanium oxide, indium oxide, tin oxide, indium tin oxide (ITO), antimony oxide, cerium oxide and other metal oxide particles, magnesium fluoride, fluorine Examples thereof include metal fluoride particles such as sodium fluoride. Among these, silica particles, zirconia particles, and alumina particles are preferable, and silica particles are particularly preferable from the viewpoint of easily improving impact resistance. These fillers can be used alone or in combination of two or more.

  The primary particle size of the filler, preferably silica particles, is preferably 1 nm or more, more preferably 3 nm or more, still more preferably 5 nm or more, particularly preferably 7 nm or more, preferably 25 nm or less, more preferably 20 nm or less, still more preferably. Is 15 nm or less, more preferably 12 nm or less, and particularly preferably less than 12 nm, and may be within a range in which these upper and lower limits are combined. When the primary particle diameter of the silica particles is not less than the above lower limit, the aggregation of the silica particles is suppressed and the optical properties of the optical film are easily improved, and when it is not more than the above upper limit, the impact resistance of the optical film is improved. Cheap. The primary particle diameter of the filler can be measured by the BET method. In addition, you may measure the primary particle diameter (average primary particle diameter) of a filler by the image analysis of a transmission electron microscope (TEM) or a scanning electron microscope (SEM).

  The average value of the equivalent circle radius of the filler, preferably silica particles, is preferably 12 nm or less, more preferably 10 nm or less, further preferably 8 nm or less, preferably 1 nm or more, more preferably 2 nm or more, and further preferably 3 nm or more. Particularly preferably, it is 4 nm or more, and may be within a range in which these upper and lower limits are combined. When the average value of the equivalent circle radius of the filler, preferably the silica particles, is not more than the above upper limit, the impact resistance of the optical film is easily improved, and when the average value is not less than the above lower limit, the silica particles are aggregated. It is easy to suppress and improve the optical properties of the optical film.

  In a preferred embodiment of the present invention, the optical film includes a polyamide-based resin and a filler having a primary particle diameter of 1 to 25 nm. In a preferred embodiment of the present invention, the optical film contains a polyimide resin and a filler having a primary particle size of 5 to 20 nm. The optical film in these preferred embodiments is excellent in impact resistance and also has excellent optical properties.

  The content of the filler, preferably silica particles, is preferably 1% by mass or more, more preferably 5% by mass or more, further preferably 10% by mass or more, and particularly preferably 20% by mass or more with respect to the mass of the optical film. Yes, preferably 60% by mass or less, more preferably 50% by mass or less, further preferably 45% by mass or less, and particularly preferably 40% by mass or less, and may be within a range in which these upper and lower limits are combined. . When the filler content is not less than the above lower limit, the impact resistance of the optical film is easily improved, and when it is not more than the above upper limit, the optical properties of the optical film are easily improved.

  The optical film of the present invention may contain an additive other than the resin and the filler. Examples of other additives include leveling agents, antioxidants, ultraviolet absorbers, bluing agents, plasticizers, and surfactants. These other additives can be used alone or in combination of two or more. When the optical film includes other additives, the content of the other additives is, for example, about 0.01 to 20 parts by mass, preferably about 0.1 to 10 parts by mass with respect to the mass of the optical film. Good.

<Optical film>
Since the optical film of the present invention contains the resin and a filler having a primary particle diameter of 25 nm or less, or a filler having an average circle equivalent radius of 12 nm or less obtained from the analysis of an SEM image, the optical film has excellent resistance. Has impact properties. Furthermore, the optical film of the present invention has excellent optical properties and high transparency. In the present specification, the optical characteristics refer to characteristics that can be optically evaluated including, for example, total light transmittance, yellowness (YI value), haze, and reflection b *. The haze and yellowness (YI value) are low, the total light transmittance is high, and the reflection b * is close to 0.

  The film thickness of the optical film of the present invention is preferably 25 μm or more, more preferably 30 μm or more, preferably 100 μm or less, more preferably 80 μm or less, still more preferably 60 μm or less, and a combination of these upper and lower limits. It may be. When the thickness of the optical film is within the above range, it is advantageous in terms of impact resistance and optical properties of the optical film. In addition, the film thickness of an optical film can be measured using a micrometer, for example, can be measured by the method as described in an Example.

  Since the optical film of the present invention is excellent in impact resistance, it is possible to suppress the occurrence of scratches such as dents or changes in the shape of the surface even when an object collides (or receives an impact) with the optical film. In the optical film of the present invention, the dent amount in the impact resistance test is preferably 15 μm or less, more preferably 10 μm or less, and further preferably 5 μm or less. It shows that it has the outstanding impact resistance in the amount of dents in an impact resistance test being below said upper limit. The amount of dents in the impact resistance test indicates an average value of the dent depth when the impact resistance test is performed five times. The depth of the dent in the impact resistance test is a laminate in which glass, an adhesive layer, and an optical film are laminated in this order, and a weight (mass 4.6 g, impact point is spherical with a diameter of 0.75 mm, made of stainless steel) ) Is dropped from the height of 10 cm onto the optical film surface of the laminate, the depth of the largest recessed point obtained by observation using an optical interference film thickness meter (the unrecessed state before the test) The shortest distance from the film surface to the most recessed point). The amount of dents in the impact resistance test can be measured, for example, by the method described in the section <Impact resistance test> in the Examples. The impact resistance test may be performed using a drop tester or the like.

  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, and further preferably 90% or more. When the total light transmittance is equal to or more than the above lower limit, the transparency becomes good, and when used for the front plate of the image display device, it can contribute to high visibility. Further, the upper limit of the total light transmittance is usually 100% or less. In addition, total light transmittance can be measured using a haze computer based on JISK7361-1: 1997, for example, can be measured by the method as described in an Example.

  The yellowness (YI value) of the optical film of the present invention is preferably 5 or less, more preferably 3 or less, and even more preferably 2.5 or less. When the yellowness of the optical film is not more than the above upper limit, the transparency becomes good, and when used for the front plate of the image display device, it can contribute to high visibility. The yellowness is usually −5 or more, preferably −2 or more. The yellowness (YI value) is determined by measuring transmittance with respect to light of 300 to 800 nm using an ultraviolet-visible near-infrared spectrophotometer to obtain tristimulus values (X, Y, Z). YI = 100 × ( 1.2769X−1.0592Z) / Y. The yellowness can be measured, for example, by the method described in the examples.

  The haze of the optical film of the present invention is preferably 1% or less, more preferably 0.5% or less, and still more preferably 0.2% or less. When the haze of the optical film is not more than the above upper limit, the transparency becomes good and can contribute to high visibility when used for the front plate of the image display device. Moreover, the lower limit of haze is 0.01% or more normally. In addition, haze can be measured using a haze computer based on JISK7136: 2000, for example, can be measured by the method as described in an Example.

  The optical film of the present invention is also excellent in surface reflection characteristics. Here, as a parameter indicating the surface reflection characteristics, for example, there is a reflection b *. The closer the reflection b * is to 0, the less the color of the optical film such as blue or yellow, and the better the transparency. The reflection b * (SCE) of the optical film of the present invention is preferably −4.0 to 4.0, more preferably −3.0 to 3.0, still more preferably −2.0 to 2.0, and further More preferably, it is -1.5-1.5, Most preferably, it is -1.0-1.0. When the reflection b * (SCE) of the optical film is in the above range, the transparency becomes good and high visibility can be exhibited when used for the front plate of the image display device. Incidentally, the reflection b * (SCE) of the optical film is b * in the L * a * b * color system of the light reflected from the optical film, which is obtained by the SCE (Special Component Excluded) method. In the present specification, CIE 1976 L * of diffuse reflected light excluding regular reflected light out of reflected light with respect to incident light in a wavelength range of 380 to 780 nm, which is incident from a direction inclined at a predetermined angle from the vertical direction of the optical film plane. The b * value of the a * b * color system.

Although the optical film of this invention is not specifically limited, For example, the following processes:
(A) a step of preparing a liquid (sometimes referred to as a varnish) containing the resin and the filler (varnish preparation step),
(B) A step of applying a varnish to a substrate to form a coating film (application step), and (c) a step of drying the applied liquid (coating layer) to form an optical film (optical film formation step). )
It can manufacture by the method containing.

  In the varnish preparation step, the resin is dissolved in a solvent, and the varnish is prepared by adding the filler and other additives as required and stirring and mixing. When silica particles are used as a filler, a silica sol in which a dispersion of silica sol containing silica particles is replaced with a solvent in which the resin can be dissolved, for example, a solvent used for preparing the following varnish, may be added to the resin. .

  The solvent used for the preparation of the varnish is not particularly limited as long as the resin can be dissolved. Examples of such solvents include amide solvents such as N, N-dimethylacetamide and N, N-dimethylformamide; lactone solvents such as γ-butyrolactone (GBL) and γ-valerolactone; dimethyl sulfone, dimethyl sulfoxide, sulfolane and the like. Sulfur-containing solvents of: carbonate solvents such as ethylene carbonate and propylene carbonate; and combinations thereof. Among these, an amide solvent or a lactone solvent is preferable. These solvents can be used alone or in combination of two or more. The varnish may contain water, alcohol solvents, ketone solvents, acyclic ester solvents, ether solvents and the like. The solid content concentration of the varnish is preferably 1 to 25% by mass, more preferably 5 to 15% by mass.

  In the coating step, a varnish is coated on the substrate to form a coating film by a known coating method. Known coating methods include, for example, roll coating methods such as wire bar coating, 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 film may be dried under an inert atmosphere or under reduced pressure.

  Examples of the substrate include a PET film, a PEN film, another polyimide resin, or a polyamide resin film. Among these, a PET film, a PEN film, and the like are preferable from the viewpoint of excellent heat resistance, and a PET film is more preferable from the viewpoints of adhesion to the optical film and cost.

  The application of the optical film of the present invention is not particularly limited and may be used for various applications. As described above, the optical film of the present invention may be a single layer or a laminate, and the optical film of the present invention may be used as it is, or a laminate with another film. May be used as In addition, when an optical film is a laminated body, all the layers laminated | stacked on the single side | surface or both surfaces of the optical film are called an optical film.

  When the optical film of the present invention is a laminate, it is preferable to have one or more functional layers on at least one surface of the optical film. Examples of the functional layer include an ultraviolet absorbing layer, a primer layer, a gas barrier layer, an adhesive layer, a hue adjusting layer, a refractive index adjusting layer, and a hard coat layer. A functional layer can be used individually or in combination of 2 or more types.

  The ultraviolet absorbing layer is a layer having an ultraviolet absorbing function. For example, a main material selected from an ultraviolet curable transparent resin, an electron beam curable transparent resin, and a thermosetting transparent resin, It is composed of dispersed UV absorbers.

  The adhesive layer is a layer having an adhesive function, and has a function of adhering the optical film to another member. As the material for forming the adhesive layer, a conventionally known material can be used. For example, a thermosetting resin composition or a photocurable resin composition can be used. In this case, the thermosetting resin composition or the photocurable resin composition can be polymerized and cured by supplying energy afterwards.

  The pressure-sensitive adhesive layer (Pressure Sensitive Adhesive, PSA), which is attached to an object by pressing, may be used as the pressure-sensitive adhesive layer. The pressure-sensitive adhesive may be a pressure-sensitive adhesive that is “a substance that is adhesive at room temperature and adheres to an adherend with light pressure” (JIS K 6800). ) And a capsule-type adhesive that can maintain stability until the coating is broken by appropriate means (pressure, heat, etc.) (JIS K 6800).

  The hue adjustment layer is a layer having a function of hue adjustment, and is a layer capable of adjusting the optical film to a target hue. A hue adjustment layer is a layer containing resin and a coloring agent, for example. Examples of the colorant include inorganic pigments such as titanium oxide, zinc oxide, dial, titanium oxide-based fired pigment, ultramarine, cobalt aluminate, and carbon black; azo-based compounds, quinacridone-based compounds, anthraquinone-based compounds, Organic pigments such as perylene compounds, isoindolinone compounds, phthalocyanine compounds, quinophthalone compounds, selenium compounds, and diketopyrrolopyrrole compounds; extender pigments such as barium sulfate and calcium carbonate; and basic dyes, Examples include acid dyes and mordant dyes.

  The refractive index adjustment layer is a layer having a function of adjusting the refractive index. For example, the refractive index adjustment layer has a refractive index different from that of a single-layer optical film and can impart a predetermined refractive index to the optical film. The refractive index adjustment layer may be, for example, an appropriately selected resin, and optionally a resin layer further containing a pigment, or may be a metal thin film. Examples of the pigment for adjusting the refractive index include silicon oxide, aluminum oxide, antimony oxide, tin oxide, titanium oxide, zirconium oxide, and tantalum oxide. The average primary particle diameter of the pigment may be 0.1 μm or less. By setting the average primary particle diameter of the pigment to 0.1 μm or less, irregular reflection of light transmitted through the refractive index adjusting layer can be prevented, and a decrease in transparency can be prevented. Examples of the metal used for the refractive index adjustment layer include metals such as titanium oxide, tantalum oxide, zirconium oxide, zinc oxide, tin oxide, silicon oxide, indium oxide, titanium oxynitride, titanium nitride, silicon oxynitride, and silicon nitride. Oxides or metal nitrides may be mentioned.

  The hard coat layer can be formed by curing a hard coat composition containing a reactive material capable of forming a crosslinked structure by irradiation with active energy rays or application of thermal energy, and is preferably formed by irradiation with active energy rays. Active energy rays are defined as energy rays that can generate active species by decomposing compounds that generate active species. Visible light, ultraviolet rays, infrared rays, X-rays, α rays, β rays, γ rays, and electron rays Etc., preferably ultraviolet rays. The hard coat composition contains at least one polymer of a radical polymerizable compound and a cationic polymerizable compound.

  The radical polymerizable compound is a compound having a radical polymerizable group. The radical polymerizable group possessed by the radical polymerizable compound may be any functional group capable of causing a radical polymerization reaction, such as a group containing a carbon-carbon unsaturated double bond, and specifically a vinyl group. , (Meth) acryloyl groups and the like. When the radical polymerizable compound has two or more radical polymerizable groups, these radical polymerizable groups may be the same or different from each other. The number of radical polymerizable groups in the molecule of the radical polymerizable compound is preferably 2 or more from the viewpoint of improving the hardness of the hard coat layer. The radical polymerizable compound is preferably a compound having a (meth) acryloyl group from the viewpoint of high reactivity, and specifically includes 2 to 6 (meth) acryloyl groups in one molecule. From several hundreds of molecular weights having several (meth) acryloyl groups in molecules called polyfunctional acrylate monomers, epoxy (meth) acrylates, urethane (meth) acrylates, and polyester (meth) acrylates Thousands of oligomers are mentioned, Preferably, 1 or more types selected from epoxy (meth) acrylate, urethane (meth) acrylate, and polyester (meth) acrylate are mentioned.

The cationic polymerizable compound is a compound having a cationic polymerizable group such as an epoxy group, an oxetanyl group, or a vinyl ether group. The number of cationically polymerizable groups in one molecule of the cationically polymerizable compound is preferably 2 or more, more preferably 3 or more, from the viewpoint of improving the hardness of the hard coat layer.
In addition, the cationic polymerizable compound is preferably a compound having at least one of an epoxy group and an oxetanyl group as a cationic polymerizable group. Cyclic ether groups such as epoxy groups and oxetanyl groups are preferred from the viewpoint of small shrinkage accompanying the polymerization reaction. In addition, compounds having an epoxy group among the cyclic ether groups are easily available as compounds having various structures, do not adversely affect the durability of the obtained hard coat layer, and easily control the compatibility with the radical polymerizable compound. There is an advantage. Of the cyclic ether groups, the oxetanyl group tends to have a higher degree of polymerization than the epoxy group, has low toxicity, and accelerates the network formation rate obtained from the cationically polymerizable compound of the obtained hard coat layer. There are advantages such as forming an independent network without leaving unreacted monomer in the film even in a region mixed with the polymerizable compound.
As the cationically polymerizable compound having an epoxy group, for example, a polyglycidyl ether of a polyhydric alcohol having an alicyclic ring, a cyclohexene ring or a cyclopentene ring-containing compound may be used with an appropriate oxidizing agent such as hydrogen peroxide or peracid. Alicyclic epoxy resin obtained by epoxidation; polyglycidyl ether of aliphatic polyhydric alcohol or alkylene oxide adduct thereof, polyglycidyl ester of aliphatic long-chain polybasic acid, homopolymer of glycidyl (meth) acrylate, Aliphatic epoxy resins such as copolymers; glycidyl esters produced by the reaction of bisphenols such as bisphenol A, bisphenol F and hydrogenated bisphenol A, or derivatives thereof such as alkylene oxide adducts and caprolactone adducts, and epichlorohydrin. Ether, and novolac epoxy resins such as a and glycidyl ether type epoxy resins derived from bisphenols are exemplified.

The hard coat composition may further include a polymerization initiator. Examples of the polymerization initiator include radical polymerization initiators, cationic polymerization initiators, radicals and cationic polymerization initiators, which are appropriately selected and used. These polymerization initiators are decomposed by at least one of active energy ray irradiation and heating to generate radicals or cations to advance radical polymerization and cationic polymerization.
The radical polymerization initiator only needs to be able to release a substance that initiates radical polymerization by at least one of irradiation with active energy rays and heating. Examples of the thermal radical polymerization initiator include organic peroxides such as hydrogen peroxide and perbenzoic acid, and azo compounds such as azobisbutyronitrile.
As active energy ray radical polymerization initiators, there are Type 1 type radical polymerization initiators that generate radicals by molecular decomposition and Type 2 type radical polymerization initiators that generate radicals by hydrogen abstraction reaction in the presence of tertiary amines. Yes, they are used alone or in combination.
The cationic polymerization initiator only needs to be capable of releasing a substance that initiates cationic polymerization by irradiation with active energy rays and / or heating. As the cationic polymerization initiator, aromatic iodonium salts, aromatic sulfonium salts, cyclopentadienyl iron (II) complexes and the like can be used. Depending on the structure, they can initiate cationic polymerization either by irradiation with active energy rays or heating, or any of them.

  The content of the polymerization initiator is preferably 0.1 to 10% by mass with respect to 100% by mass of the entire hard coat composition. When the content of the polymerization initiator is in the above range, curing can sufficiently proceed, and the mechanical properties and adhesion of the finally obtained coating film can be in a good range, There is a tendency that adhesion failure, cracking phenomenon and curling phenomenon due to curing shrinkage hardly occur.

The hard coat composition may further include one or more selected from the group consisting of a solvent and an additive.
The solvent can dissolve or disperse the polymerizable compound and the polymerization initiator, and does not hinder the effects of the present invention as long as it is a solvent known as a hard coat composition solvent in this technical field. In range, can be used.
The additive may further include inorganic particles, a leveling agent, a stabilizer, a surfactant, an antistatic agent, a lubricant, an antifouling agent, and the like.

  The thickness of a hard-coat layer is not specifically limited, For example, 2-100 micrometers may be sufficient. When the thickness of the hard coat layer is in the above range, sufficient scratch resistance can be ensured, the flex resistance is not easily lowered, and the problem of curling due to curing shrinkage tends not to occur. .

  The optical film may further include a protective film. The protective film may be laminated on one side or both sides of the optical film. When having a functional layer on one side of the optical film, the protective film may be laminated on the surface on the optical film side or the surface on the functional layer side, and is laminated on both the optical film side and the functional layer side. Also good. When it has a functional layer on both surfaces of an optical film, the protective film may be laminated | stacked on the surface by the side of one functional layer, and may be laminated | stacked on the surface by the side of both functional layers. The protective film is a film for temporarily protecting the surface of the optical film or the functional layer, and is not particularly limited as long as it is a peelable film that can protect the surface of the optical film or the functional layer. Examples of the protective film include polyester resin films such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate; polyolefin resin films such as polyethylene and polypropylene films, acrylic resin films, and the like. It is preferably selected from the group consisting of a terephthalate resin film and an acrylic resin film. When the optical film has two protective films, each protective film may be the same or different.

  Although the thickness of a protective film is not specifically limited, Usually, 10-100 micrometers, Preferably it is 10-80 micrometers, More preferably, it is 10-50 micrometers. When the optical film has two protective films, the thickness of each protective film may be the same or different.

  Since the optical film of the present invention is excellent in impact resistance and optical characteristics, it can be suitably used as an optical film in an image display device or the like. The optical film of the present invention is preferably useful as a front plate of an image display device, particularly as a front plate (window film) of a flexible image display device (flexible display). The flexible display includes, for example, a flexible functional layer and an optical film that is stacked on the flexible functional layer and functions as a front plate. That is, the front plate of the flexible display is arranged on the viewing side on the flexible functional layer. This front plate has a function of protecting the flexible functional layer. In addition, since it is excellent in impact resistance, it is difficult to cause damage due to contact of the flexible image display device, which can contribute to energy saving.

  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 is all image display devices having flexible characteristics.

[Flexible image display device]
The present invention includes a flexible image display device including the optical film of the present invention. As described above, the optical film of the present invention is preferably used as a front plate in a flexible image display device, and the front plate may be referred to as a window film. The flexible image display device includes a laminate for a flexible image display device and an organic EL display panel, and the flexible image display device laminate is arranged on the viewing side with respect to the organic EL display panel, and is configured to be bendable. Yes. As a laminate for a flexible image display device, it may contain a window film, a polarizing plate, and a touch sensor, and the stacking order is arbitrary, but from the viewing side, the window film, the polarizing plate, the touch sensor or the window film, It is preferable that the touch sensor and the polarizing plate are laminated in this order. The presence of a polarizing plate on the viewing side of the touch sensor is preferable because the touch sensor pattern is less visible and the visibility of the display image is improved. Each member can be laminated | stacked using an adhesive agent, an adhesive, etc. Moreover, the light-shielding pattern formed in at least one surface of the any one layer of the said window film, a polarizing plate, and a touch sensor can be comprised.

[Polarizer]
As described above, the flexible image display device of the present invention contains a polarizing plate, preferably a circularly polarizing plate. The circularly polarizing plate is a functional layer having a function of transmitting only a right or left circularly polarized component by laminating a λ / 4 retardation plate on a linearly polarizing plate. For example, external light is converted into right circularly polarized light, the external light reflected by the organic EL panel and turned into left circularly polarized light is blocked, and only the light emitting component of the organic EL is transmitted to suppress the influence of the reflected light and image Used to make it easier to see. In order to achieve the circular polarization function, the absorption axis of the linearly polarizing plate and the slow axis of the λ / 4 retardation plate need to be 45 ° theoretically, but practically 45 ± 10 °. The linearly polarizing plate and the λ / 4 retardation plate are not necessarily laminated adjacent to each other as long as the relationship between the absorption axis and the slow axis satisfies the above range. Although it is preferable to achieve complete circular polarization at all wavelengths, the circular polarization plate in the present invention includes an elliptical polarization plate because it is not always necessary in practice. It is also preferable to further improve the visibility in a state where polarized sunglasses are applied by laminating a λ / 4 retardation film on the viewing side of the linearly polarizing plate and making the emitted light circularly polarized.

The linear polarizing plate is a functional layer having a function of blocking polarized light having a vibration component perpendicular to the light that is oscillating in the transmission axis direction. The linear polarizing plate may include a linear polarizer alone or a linear polarizer and a protective film attached to at least one surface thereof. The linear polarizing plate may have a thickness of 200 μm or less, preferably 0.5 to 100 μm. When the thickness is in the above range, flexibility tends to be difficult to decrease.
The linear polarizer may be a film-type polarizer manufactured by dyeing and stretching a polyvinyl alcohol (PVA) film. A dichroic dye such as iodine is adsorbed on a PVA-based film oriented by stretching or is stretched in a state of being adsorbed to PVA, whereby the dichroic dye is oriented and exhibits polarizing performance. In the production of the film-type polarizer, other processes such as swelling, crosslinking with boric acid, washing with an aqueous solution, and drying may be included. The stretching or dyeing process may be performed by a PVA film alone or in a state where it is laminated with another film such as polyethylene terephthalate. The thickness of the PVA film used is preferably 10 to 100 μm, and the draw ratio is preferably 2 to 10 times.
Furthermore, as another example of the polarizer, a liquid crystal-coated polarizer formed by coating a liquid crystal polarizing composition may be used. The liquid crystal polarizing composition may include a liquid crystal compound and a dichroic dye compound. The liquid crystalline compound only needs to have the property of exhibiting a liquid crystal state. In particular, the liquid crystalline compound preferably has a higher-order alignment state such as a smectic phase because it can exhibit high polarization performance. The liquid crystal compound preferably has a polymerizable functional group.

The dichroic dye is a dye that is aligned with the liquid crystal compound and exhibits dichroism, and the dichroic dye itself may have liquid crystallinity or have a polymerizable functional group. You can also Any compound in the liquid crystal polarizing composition has a polymerizable functional group.
The liquid crystal polarizing composition may further contain an initiator, a solvent, a dispersant, a leveling agent, a stabilizer, a surfactant, a crosslinking agent, a silane coupling agent, and the like.
The liquid crystal polarizing layer is manufactured by applying a liquid crystal polarizing composition on an alignment film to form a liquid crystal polarizing layer.
The liquid crystal polarizing layer can be formed thinner than a film-type polarizer. The thickness of the liquid crystal polarizing layer may be preferably 0.5 to 10 μm, more preferably 1 to 5 μm.
The alignment film can be produced, for example, by applying an alignment film forming composition on a substrate and imparting alignment by rubbing, polarized light irradiation, or the like. The alignment film forming composition may contain a solvent, a crosslinking agent, an initiator, a dispersant, a leveling agent, a silane coupling agent and the like in addition to the aligning agent. Examples of the aligning agent include polyvinyl alcohols, polyacrylates, polyamic acids, and polyimides. When applying photo-alignment, it is preferable to use an aligning agent containing a cinnamate group. The polymer used as the aligning agent may have a weight average molecular weight of about 10,000 to 1,000,000. The thickness of the alignment film is preferably 5 to 10,000 nm, more preferably 10 to 500 nm, from the viewpoint of the alignment regulating force. The liquid crystal polarizing layer can be peeled off from the base material, transferred and laminated, or the base material can be laminated as it is. It is also preferable that the base material plays a role as a transparent base material for a protective film, a retardation plate, or a window.

  The protective film may be a transparent polymer film, and materials and additives used for the transparent substrate can be used. A cellulose film, an olefin film, an acrylic film, and a polyester film are preferred. It may be a coating-type protective film obtained by applying and curing a cationic curing composition such as an epoxy resin or a radical curing composition such as an acrylate. If necessary, plasticizers, ultraviolet absorbers, infrared absorbers, colorants such as pigments and dyes, fluorescent brighteners, dispersants, thermal stabilizers, light stabilizers, antistatic agents, antioxidants, lubricants, solvents, etc. May be included. The protective film may have a thickness of 200 μm or less, preferably 1 to 100 μm. When the thickness of the protective film is within the above range, the flexibility of the protective film is difficult to decrease. The protective film can also serve as a transparent substrate of the window.

The λ / 4 phase difference plate is a film that gives a phase difference of λ / 4 in a direction (in-plane direction of the film) perpendicular to the traveling direction of incident light. The λ / 4 retardation plate may be a stretched retardation plate manufactured by stretching a polymer film such as a cellulose film, an olefin film, or a polycarbonate film. If necessary, retardation adjusting agents, plasticizers, UV absorbers, infrared absorbers, colorants such as pigments and dyes, fluorescent brighteners, dispersants, heat stabilizers, light stabilizers, antistatic agents, antioxidants Further, it may contain a lubricant, a solvent and the like. The stretchable retardation plate may have a thickness of 200 μm or less, preferably 1 to 100 μm. When the thickness is in the above range, the flexibility of the film tends not to decrease.
Furthermore, as another example of the λ / 4 retardation plate, a liquid crystal coating type retardation plate formed by applying a liquid crystal composition may be used. The liquid crystal composition includes a liquid crystal compound having a property of exhibiting a liquid crystal state, such as nematic, cholesteric, and smectic. Any compound including a liquid crystal compound in the liquid crystal composition has a polymerizable functional group. The liquid crystal-coated retardation plate may further contain an initiator, a solvent, a dispersant, a leveling agent, a stabilizer, a surfactant, a crosslinking agent, a silane coupling agent, and the like. The liquid crystal coating type retardation plate can be produced by coating and curing a liquid crystal composition on an alignment film to form a liquid crystal retardation layer, as described for the liquid crystal polarizing layer. The liquid crystal coated retardation plate can be formed thinner than the stretched retardation plate. The thickness of the liquid crystal polarizing layer may be usually 0.5 to 10 μm, preferably 1 to 5 μm. The liquid crystal coating type retardation plate can be peeled off from the substrate, transferred, and laminated, or the substrate can be laminated as it is. It is also preferable that the base material plays a role as a transparent base material for a protective film, a retardation plate, or a window.

In general, there are many materials that exhibit higher birefringence as the wavelength is shorter and smaller birefringence as the wavelength is longer. In this case, since a phase difference of λ / 4 cannot be achieved in the entire visible light region, an in-plane phase difference of 100 to 180 nm, preferably 130, becomes λ / 4 with respect to the vicinity of 560 nm having high visibility. Often designed to be ˜150 nm. It is preferable to use a reverse dispersion λ / 4 phase difference plate using a material having birefringence wavelength dispersion characteristics opposite to that of normal, since the visibility can be improved. As such a material, it is also preferable to use a material described in Japanese Patent Application Laid-Open No. 2007-232873 in the case of a stretch-type phase difference plate and a method described in Japanese Patent Application Laid-Open No. 2010-30979 in the case of a liquid crystal coating type phase difference plate. .
As another method, a technique for obtaining a broadband λ / 4 phase difference plate by combining with a λ / 2 phase difference plate is also known (Japanese Patent Laid-Open No. 10-90521). The λ / 2 phase difference plate is also manufactured by the same material method as the λ / 4 phase difference plate. Although the combination of the stretchable retardation plate and the liquid crystal coating type retardation plate is arbitrary, it is preferable to use the liquid crystal coating type retardation plate for both because the thickness can be reduced.
A method of laminating a positive C plate on the circularly polarizing plate to improve visibility in an oblique direction is also known (Japanese Patent Laid-Open No. 2014-224837). The positive C plate may also be a liquid crystal coated retardation plate or a stretched retardation plate. The retardation in the thickness direction is -200 to -20 nm, preferably -140 to -40 nm.

[Touch sensor]
The flexible image display device of the present invention contains a touch sensor as described above. The touch sensor is used as input means. Various types of touch sensors such as a resistive film method, a surface acoustic wave method, an infrared method, an electromagnetic induction method, and a capacitance method have been proposed, and any method may be used. Of these, the electrostatic capacity method is preferable. The capacitive touch sensor is divided into an active region and a non-active region located in an outer portion of the active region. The active area is an area corresponding to an area (display unit) where the screen is displayed on the display panel, and is an area where a user's touch is sensed. An inactive area is an area where the screen is not displayed on the display device (non-display area). This is a region corresponding to the display unit. The touch sensor includes a flexible substrate; a sensing pattern formed in an active region of the substrate; and formed in an inactive region of the substrate and connected to an external driving circuit through the sensing pattern and a pad portion. Each sensing line can be included. As the substrate having flexible characteristics, the same material as the transparent substrate of the window can be used. The substrate of the touch sensor preferably has a toughness of 2,000 MPa% or more from the viewpoint of suppressing cracks in the touch sensor. More preferably, the toughness may be 2,000 to 30,000 MPa%. Here, toughness is defined as a lower area of a curve up to a fracture point in a stress (MPa) -strain (%) curve (Stress-strain curve) obtained through a tensile test of a polymer material.

  The sensing pattern may include a first pattern formed in a first direction and a second pattern formed in a second direction. The first pattern and the second pattern are arranged in different directions. The first pattern and the second pattern are formed in the same layer, and each pattern must be electrically connected in order to sense a touched point. The first pattern is a form in which each unit pattern is connected to each other through a joint, but the second pattern has a structure in which each unit pattern is separated from each other in an island form. A separate bridge electrode is required for connection. A known transparent electrode material can be applied to the sensing pattern. For example, indium tin oxide (ITO), indium zinc oxide (IZO), zinc oxide (ZnO), indium zinc tin oxide (IZTO), indium gallium zinc oxide (IGZO), cadmium tin oxide (CTO) , PEDOT (poly (3,4-ethylenedithiothiophene)), carbon nanotube (CNT), graphene, metal wire, and the like. These can be used alone or in combination of two or more. Preferably ITO can be used. The metal used for the metal wire is not particularly limited, and examples thereof include silver, gold, aluminum, copper, iron, nickel, titanium, telenium, and chromium. These can be used alone or in admixture of two or more.

The bridge electrode can be formed on the sensing pattern via the insulating layer and on the insulating layer. The bridge electrode is formed on the substrate, and the insulating layer and the sensing pattern can be formed thereon. The bridge electrode may be formed of the same material as the sensing pattern, and is formed of a metal such as molybdenum, silver, aluminum, copper, palladium, gold, platinum, zinc, tin, titanium, or an alloy of two or more of these. You can also Since the first pattern and the second pattern must be electrically insulated, an insulating layer is formed between the sensing pattern and the bridge electrode. The insulating layer may be formed only between the joint of the first pattern and the bridge electrode, or may be formed in a layer structure covering the sensing pattern. In the latter case, the bridge electrode can be connected to the second pattern via a contact hole formed in the insulating layer. The touch sensor has a transmittance difference between a pattern area where a pattern is formed and a non-pattern area where a pattern is not formed, specifically, a light transmittance induced by a difference in refractive index in these areas. As a means for appropriately compensating for the difference, an optical adjustment layer may be further included between the substrate and the electrode, and the optical adjustment layer may include an inorganic insulating material or an organic insulating material. The optical adjustment layer can be formed by coating a photocurable composition containing a photocurable organic binder and a solvent on a substrate. The photocurable composition may further include inorganic particles. The refractive index of the optical adjustment layer can be increased by the inorganic particles.
The photocurable organic binder can include, for example, a copolymer of monomers such as an acrylate monomer, a styrene monomer, and a carboxylic acid monomer. The photocurable organic binder may be a copolymer including different repeating units such as an epoxy group-containing repeating unit, an acrylate repeating unit, and a carboxylic acid repeating unit.
Examples of the inorganic particles include zirconia particles, titania particles, and alumina particles. The photocurable composition may further contain additives such as a photopolymerization initiator, a polymerizable monomer, and a curing auxiliary agent.

[Adhesive layer]
Each layer (window, circular polarizing plate, touch sensor) forming the flexible image display device laminate and a film member (linear polarizing plate, λ / 4 retardation plate, etc.) forming each layer may be formed by an adhesive. it can. Adhesives include water based adhesives, organic solvent based, solventless based adhesives, solid adhesives, solvent volatilizing adhesives, moisture curable adhesives, heat curable adhesives, anaerobic curable adhesives, and active energy ray curable adhesives. Commonly used materials such as an adhesive, a curing agent mixed adhesive, a hot-melt adhesive, a pressure-sensitive adhesive (adhesive), and a rewet adhesive can be used. Of these, water-based solvent volatile adhesives, active energy ray-curable adhesives, and pressure-sensitive adhesives are often used. The thickness of the adhesive layer can be appropriately adjusted according to the required adhesive force and the like, and is 0.01 to 500 μm, preferably 0.1 to 300 μm. Although present, each thickness and the type of pressure-sensitive adhesive used may be the same or different.

  As the water-based aqueous solvent volatilization type adhesive, water-soluble polymers such as polyvinyl alcohol polymers and starches, water-dispersed polymers such as ethylene-vinyl acetate emulsions and styrene-butadiene emulsions can be used as the main polymer. In addition to water and the main polymer, a crosslinking agent, a silane compound, an ionic compound, a crosslinking catalyst, an antioxidant, a dye, a pigment, an inorganic filler, an organic solvent, and the like may be blended. In the case of bonding with the aqueous aqueous solvent volatile adhesive, the aqueous aqueous solvent volatile adhesive is injected between the layers to be bonded and bonded to the adherent layer, and then dried to provide adhesion. . The thickness of the adhesive layer in the case of using the aqueous aqueous solvent volatilization type adhesive may be 0.01 to 10 μm, preferably 0.1 to 1 μm. In the case where the pre-aqueous solvent volatile adhesive is used for forming a plurality of layers, the thickness of each layer and the kind of the adhesive may be the same or different.

  The active energy ray-curable adhesive can be formed by curing an active energy ray-curable composition containing a reactive material that irradiates active energy rays to form an adhesive layer. The active energy ray-curable composition can contain at least one polymer of a radical polymerizable compound and a cationic polymerizable compound similar to the hard coat composition. The radical polymerizable compound is the same as the hard coat composition, and the same kind as the hard coat composition can be used. As the radical polymerizable compound used for the adhesive layer, a compound having an acryloyl group is preferable. It is also preferable to contain a monofunctional compound in order to lower the viscosity of the adhesive composition.

The cationic polymerizable compound is the same as that of the hard coat composition, and the same kind as that of the hard coat composition can be used. As the cationic polymerizable compound used in the active energy ray-curable composition, an epoxy compound is particularly preferable. In order to reduce the viscosity of the adhesive composition, it is also preferable to include a monofunctional compound as a reactive diluent.
The active energy ray composition may further contain a polymerization initiator. Examples of the polymerization initiator include radical polymerization initiators, cationic polymerization initiators, radicals and cationic polymerization initiators, which can be appropriately selected and used. These polymerization initiators are decomposed by at least one of active energy ray irradiation and heating to generate radicals or cations to advance radical polymerization and cationic polymerization. In the description of the hard coat composition, an initiator capable of initiating at least one of radical polymerization or cationic polymerization by irradiation with active energy rays can be used.

  The active energy ray curable composition further includes an ion scavenger, an antioxidant, a chain transfer agent, an adhesion promoter, a thermoplastic resin, a filler, a flow viscosity modifier, a plasticizer, an antifoaming solvent, an additive, a solvent. Can be included. When adhering with the active energy ray curable adhesive, the active energy ray curable composition is applied to either or both of the adherend layers and then bonded, and the active energy ray curable composition is activated through either of the adherent layers or both of the adherent layers. It can be bonded by irradiating with energy rays and curing. When the active energy ray-curable adhesive is used, the thickness of the adhesive layer may be 0.01 to 20 μm, preferably 0.1 to 10 μm. When the active energy ray-curable adhesive is used for forming a plurality of layers, the thickness of each layer and the type of the adhesive used may be the same or different.

  The pressure-sensitive adhesive is classified into an acrylic pressure-sensitive adhesive, a urethane pressure-sensitive adhesive, a rubber pressure-sensitive adhesive, a silicone pressure-sensitive adhesive, and the like depending on the main polymer, and any of them can be used. In addition to the main polymer, the adhesive may contain a crosslinking agent, a silane compound, an ionic compound, a crosslinking catalyst, an antioxidant, a tackifier, a plasticizer, a dye, a pigment, an inorganic filler, and the like. Each component constituting the pressure-sensitive adhesive is dissolved / dispersed in a solvent to obtain a pressure-sensitive adhesive composition, and the pressure-sensitive adhesive composition is coated on a substrate and then dried to form a pressure-sensitive adhesive layer adhesive layer. The The pressure-sensitive adhesive layer may be directly formed, or a layer separately formed on the substrate can be transferred. In order to cover the adhesive surface before bonding, it is also preferred to use a release film. When the pressure-sensitive adhesive is used, the thickness of the adhesive layer may be 1 to 500 μm, preferably 2 to 300 μm. When the first-stage pressure-sensitive adhesive is used for forming a plurality of layers, the thickness of each layer and the type of pressure-sensitive adhesive used may be the same or different.

[Shading pattern]
The light shielding pattern can be applied as at least a part of a bezel or a housing of a flexible image display device in the previous period. The visibility of the image is improved by concealing the wiring arranged at the edge portion of the flexible image display device by the light shielding pattern and making it difficult to see. The light shielding pattern may be a single layer or a multilayer. The color of the light-shielding pattern is not particularly limited, and can have various colors such as black, white, and metal color. The light shielding pattern can be formed of a pigment for embodying a color and a polymer such as an acrylic resin, an ester resin, an epoxy resin, polyurethane, or silicone. These can be used alone or in a mixture of two or more. The light shielding pattern can be formed by various methods such as printing, lithography, and inkjet. The thickness of the light shielding pattern is usually 1 to 100 μm, preferably 2 to 50 μm. It is also preferable to give a shape such as an inclination in the thickness direction of the light pattern.

  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 specified, “%” and “part” in the examples mean mass% and part by mass. First, measurement and evaluation methods will be described.

<Primary particle diameter of silica particles>
The primary particle diameter of the silica particles in Examples and Comparative Examples was measured and evaluated by the BET method.

<Circle equivalent radius of silica particles>
The circle-equivalent radius of the silica primary particles in the films in Examples and Comparative Examples was evaluated by image analysis of electron microscope images. SEM images of each film (image size: 1280 pixels × 898 pixels, pixel size: 2.48 nm / pixel) were photographed, and binarized images were obtained by Otsu's automatic discrimination method. Using Watershed of the image analysis software ImageJ, the particle was divided into primary particles, then Executed Despeckle, again executed Watershed, and the Area (number of pixels) of each primary particle was calculated from the Analyze Particles of the image analysis software ImageJ. However, 2 pixels or less were judged as noise and excluded from the totalization. The equivalent circle radius R (nm) of each primary particle was obtained by the following formula.
R = 2.48 × (Area / 3.14) ^0.5
From the circle equivalent radius distribution obtained from the circle equivalent radius R of each primary particle, the average value of the circle equivalent radii of the silica particles (silica primary particles) was determined.

<Haze>
In accordance with JIS K 7136: 2000, the optical films obtained in Examples and Comparative Examples were cut into a size of 30 mm × 30 mm, and a haze computer (“HGM-2DP” manufactured by Suga Test Instruments Co., Ltd.) was used. Using, haze (%) was measured.

<Yellowness (YI value)>
The yellowness (Yellow Index: YI value) of the optical films obtained in Examples and Comparative Examples was measured using an ultraviolet-visible near-infrared spectrophotometer “V-670” manufactured by JASCO Corporation. After measuring the background without a sample, set the optical film on the sample holder, measure the transmittance for light of 300 to 800 nm, and obtain the tristimulus values (X, Y, Z). YI value was calculated based on the above.
YI = 100 × (1.2769X−1.0592Z) / Y

<Total light transmittance (Tt)>
In accordance with JIS K 7361-1: 1997, the optical films obtained in Examples and Comparative Examples were cut into a size of 30 mm × 30 mm, and a haze computer (“HGM-2DP” manufactured by Suga Test Instruments Co., Ltd.) ) Was used to measure the total light transmittance (%) at an optical film thickness of 50 μm.

<Reflection b *>
Spectral colorimetry for samples prepared by cutting the optical films obtained in Examples and Comparative Examples to a size of 50 × 50 mm and affixing to black PET (manufactured by Yodogawa Paper Co., Ltd., “Kukiri Mieru”) The SCE (excluding regular reflection) was measured using a meter (“CM-3700A” manufactured by Konica Minolta, Inc.), and the value of reflection b * (SCE) was obtained.

<Impact resistance test>
-Preparation of sample for impact resistance evaluation In a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, a dropping device and a nitrogen introduction tube, 97.0 parts by mass of n-butyl acrylate, 1.0 part by mass of acrylic acid, 0.5 parts by mass of 2-hydroxyethyl acrylate, 200 parts by mass of ethyl acetate, and 0.08 parts by mass of 2,2′-azobisisobutyronitrile were charged, and the air in the reaction vessel was replaced with nitrogen gas. . While stirring under a nitrogen atmosphere, the reaction solution was heated to 60 ° C., reacted for 6 hours, and then cooled to room temperature. When the weight average molecular weight of a part of the obtained solution was measured, production of 1,800,000 (meth) acrylic acid ester polymer was confirmed.

100 parts by mass of the (meth) acrylic acid ester polymer obtained in the above process (converted to solid content; the same shall apply hereinafter) and trimethylolpropane-modified tolylene diisocyanate (trade name, manufactured by Tosoh Corporation) as an isocyanate crosslinking agent "Coronate (registered trademark) L") 0.30 parts by mass and, as a silane coupling agent, 3-glycidoxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., trade name "KBM403") 0.30 parts by mass Were mixed, sufficiently stirred, and diluted with ethyl acetate to obtain a coating solution of the pressure-sensitive adhesive composition.
After applying the coating solution on the release treatment surface (peeling layer surface) of the separator (manufactured by Lintec Corporation: SP-PLR382190) with an applicator so that the thickness after drying becomes 25 μm, at 100 ° C. Dry for 1 minute, and paste another separator (Lintec Co., Ltd .: SP-PLR381031) on the side opposite to the side where the separator of the pressure-sensitive adhesive layer is bonded. Obtained.

  A pressure-sensitive adhesive layer is formed by transferring the pressure-sensitive adhesive layer from the pressure-sensitive adhesive layer with a double-sided separator to glass, and the optical films obtained in Examples and Comparative Examples are bonded onto the pressure-sensitive adhesive layer to form a glass, adhesive A laminate (a sample for impact resistance evaluation) in which the agent layer and the optical film were laminated in this order was obtained.

-Impact resistance evaluation Impact resistance was evaluated. Specifically, a weight was dropped from a height of 10 cm onto the optical film surface of the laminate (impact resistance evaluation sample) to prepare a dent. The weight is 4.6 g in mass, and the portion that collides with the optical film surface is spherical with a diameter of 0.75 mm and is made of stainless steel. Next, the shape of the dent on the optical film surface was observed using an optical interference film thickness meter ("Micromap (MM557N-M100 type)" manufactured by Ryoka System Co., Ltd.), and the dent was not in the state before the test. The depth of the largest recessed point (the shortest distance from the unrecessed film surface before the test to the largest recessed point) was measured on the basis of the film surface. The measurement was repeated 5 times, and the average value of the dent depth was defined as the dent amount in the impact resistance test.

<Weight average molecular weight (Mw)>
Gel Permeation Chromatography (GPC) Measurement / Pretreatment Method A DMF eluent (10 mM lithium bromide solution) is added to the polyamideimide obtained in the example to a concentration of 2 mg / mL, and the mixture is stirred at 80 ° C. for 30 minutes. The solution was heated, 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 film thicknesses of the optical films obtained in Examples and Comparative Examples were measured using a micrometer manufactured by Mitutoyo Corporation.

[Example 1]
(Preparation of silica sol)
A 1000 mL flask was charged with 523.8 g of methanol-dispersed silica sol (primary particle size 11 nm, silica solid content 21.0%) and 440.0 g of γ-butyrolactone (GBL), and 1 at 400 hPa in a 45 ° C. hot water bath with a vacuum evaporator. The methanol was evaporated for 1 hour at 250 hPa for 1 hour. Further, the temperature was raised to 70 ° C. under 250 hPa and heated for 30 minutes to obtain γ-butyrolactone-dispersed silica sol 1 (GBL-dispersed silica sol 1). The obtained GBL-dispersed silica sol 1 had a solid content concentration of 19.3%.

(Preparation of polyamideimide)
Under a nitrogen gas atmosphere, in a 1 L separable flask equipped with a stirring blade, 45 g (140.52 mmol) of 2,2′-bis (trifluoromethyl) -4,4′-diaminodiphenyl (TFMB) and N, N-dimethyl were added. Acetamide (DMAc) 768.55 g was added, and TFMB was dissolved in DMAc while stirring at room temperature. Next, 18.92 g (42.58 mmol) of 4,4 ′-(hexafluoroisopropylidene) diphthalic dianhydride (6FDA) was added to the flask and stirred at room temperature for 3 hours. Thereafter, 4.19 g (14.19 mmol) of 4,4′-oxybis (benzoyl chloride) (OBBC) and then 17.29 g (85.16 mmol) of terephthaloyl chloride (TPC) were added to the flask and stirred at room temperature for 1 hour. did. Next, 4.63 g (49.68 mmol) of 4-methylpyridine and 13.04 g (127.75 mmol) of acetic anhydride were added to the flask. After stirring at room temperature for 30 minutes, 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 polyamideimide 1. The weight average molecular weight of the obtained polyamideimide 1 was 400,000.

(Manufacture of optical films)
Polyamideimide 1 was dissolved in GBL, and the above GBL-dispersed silica sol was added and mixed well to obtain a polyamideimide 1 / silica particle mixed varnish. The ratio of polyamideimide 1 and silica particles was 70:30. Moreover, it prepared so that the polyamideimide 1 / silica particle density | concentration (total mass of resin and a silica particle with respect to the mass of a varnish) might be 10 mass%.
After filtering the obtained mixed varnish with a filter having an opening of 10 micrometers, the film thickness of the free-standing film is 55 μm on the smooth surface of the polyester base material (trade name “A4100” manufactured by Toyobo Co., Ltd.). The film was applied using an applicator, dried at 50 ° C. for 30 minutes, then at 140 ° C. for 15 minutes, and the polyester substrate was peeled off to obtain a self-supporting film. The self-supporting film was fixed to a metal frame and dried at 200 ° C. to obtain an optical film 1 having a thickness of 50 μm.

[Example 2]
(Preparation of silica sol)
509.6 g of methanol-dispersed silica sol (primary particle size 10 nm, silica solid content 15.7%) and GBL 436.1 g were placed in a 1000 mL flask, and heated in a 45 ° C. water bath with a vacuum evaporator at 400 hPa for 1 hour and 250 hPa for 1 hour. Methanol was evaporated. Further, the temperature was raised to 70 ° C. under 250 hPa and heated for 30 minutes to obtain γ-butyrolactone-dispersed silica sol 2 (GBL-dispersed silica sol 2). The obtained GBL-dispersed silica sol 2 had a solid content concentration of 15.4%.

(Preparation of polyamideimide and production of optical film)
As the GBL-dispersed silica sol, an optical film was obtained in the same manner as in Example 1 except that the GBL-dispersed silica sol 2 having a silica particle primary particle diameter of 10 nm was used.

[Example 3]
(Preparation of silica sol)
In a 1000 mL flask, 398.5 g of methanol-dispersed silica sol (primary particle size 12 nm, silica solid content 31.1%) and 272.2 g of GBL were placed. In a 45 ° C. hot water bath with a vacuum evaporator, 400 hPa for 1 hour, 250 hPa for 1 hour. Methanol was evaporated. Further, the temperature was raised to 70 ° C. under 250 hPa and heated for 30 minutes to obtain γ-butyrolactone-dispersed silica sol 3 (GBL-dispersed silica sol 3). The solid content concentration of the obtained GBL-dispersed silica sol 3 was 30.9%.

(Preparation of polyamideimide and production of optical film)
As the GBL-dispersed silica sol, an optical film was obtained in the same manner as in Example 1 except that the GBL-dispersed silica sol 3 having a primary particle diameter of 12 nm was used.

[Example 4]
(Preparation of silica sol)
In a 1000 mL flask, 398.1 g of methanol-dispersed silica sol (primary particle diameter 21 nm, silica solid content 30.9%) and GBL 269.9 g were placed, and a vacuum evaporator at 45 ° C. in a hot water bath at 400 hPa for 1 hour, 250 hPa for 1 hour. Methanol was evaporated. Further, the temperature was raised to 70 ° C. under 250 hPa and heated for 30 minutes to obtain γ-butyrolactone-dispersed silica sol 4 (GBL-dispersed silica sol 4). The solid content concentration of the obtained GBL-dispersed silica sol 4 was 30.3%.

(Preparation of polyamideimide and production of optical film)
As the GBL-dispersed silica sol, an optical film was obtained in the same manner as in Example 1 except that the GBL-dispersed silica sol 4 having a primary particle diameter of 21 nm was used.

[Example 5]
(Preparation of polyamideimide)
Under a nitrogen gas atmosphere, 53.05 g (165.66 mmol) of TFMB and 670.91 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, 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, 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 polyamideimide 2. The obtained polyamide-imide 2 had a weight average molecular weight of 190,000.

(Manufacture of optical films)
An optical film was obtained in the same manner as in Example 1 except that the polyamideimide 2 was used as the polyamideimide.

[Comparative Example 1]
(Preparation of silica sol)
In a 1,000 mL flask, 442.6 g of methanol-dispersed silica sol (primary particle diameter 27 nm, silica particle solid content 30.5%) and GBL 301.6 g were placed, and a vacuum evaporator in a 45 ° C. water bath at 400 hPa for 1 hour. Methanol was evaporated at 250 hPa for 1 hour. Further, the temperature was raised to 70 ° C. under 250 hPa and heated for 30 minutes to obtain GBL-dispersed silica sol 5. The obtained GBL-dispersed silica sol 5 had a solid content concentration of 28.9%.

(Preparation of polyamideimide and production of optical film)
As the GBL-dispersed silica sol, an optical film was obtained in the same manner as in Example 1 except that the GBL-dispersed silica sol 5 having a primary particle diameter of 27 nm was used.

[Comparative Example 2]
An optical film was obtained in the same manner as in Comparative Example 1, except that polyimide (“KPI-MX300F” manufactured by Kawamura Sangyo Co., Ltd.) was used instead of polyamideimide.

[Comparative Example 3]
An optical film was obtained in the same manner as in Example 1 except that the varnish was prepared so that the concentration of polyamideimide (mass of polyamideimide relative to the mass of varnish) was 6 mass% without using methanol-dispersed silica.

  In the optical films obtained in Examples 1 to 5 and Comparative Examples 1 to 3, the type of resin, silica content, primary particle diameter of silica, equivalent circle radius of silica, dent amount in impact resistance test, total light transmission The rate, yellowness, haze, and reflection b * are shown in Table 1. In Table 1, PAI (1) indicates polyamideimide 1, PAI (2) indicates polyamideimide 2, PI indicates polyimide, and the silica content (% by mass) indicates the mass of the optical film (resin and silica particles). The total mass of the silica particles).

  As shown in Table 1, it was confirmed that the optical films of Examples 1 to 5 had significantly less dents in the impact resistance test than the optical films of Comparative Examples 1 to 3, and were excellent in impact resistance. It was. In addition, it was confirmed that the optical film of Example 1 had high total light transmittance, low yellowness and low haze, reflection b * was close to 0, and excellent optical characteristics.

Claims (12)

Formula (13)

[In Formula (13), G ³ and A ³ are each independently a divalent organic group]
A repeating structural unit represented by formula (10):

[In Formula (10), G is a tetravalent organic group, and A is a divalent organic group]
In a polyamide-imide containing repeating structural units represented, viewed contains a filler primary particle size measured by the BET method is 25nm or less, at least 30 mole% of G ³ in formula (13) formula (3)

[In Formula (3), R ^{1 to} R ⁸ each independently represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an aryl group having 6 to 12 carbon atoms, and hydrogen contained in R ^{1 to} R ^8. atoms each independently may be substituted with a halogen atom, B represents a single _{bond, -O -, - CH 2 -} , - CH 2 -CH 2 -, - CH (CH 3) -, - C (CH ₃ ) ₂ —, —C (CF ₃ ) ₂ —, —SO ₂ —, —S—, —CO— or —N (R ⁹ ) — is represented, and R ⁹ is substituted with a hydrogen atom or a halogen atom. Represents an optionally substituted hydrocarbon group having 1 to 12 carbon atoms, n is an integer of 0 to 4, and * represents a bond.
An optical film represented by   The optical film of Claim 1 whose primary particle diameter of the said filler is 1 nm or more. Formula (13)

[In Formula (13), G ³ and A ³ are each independently a divalent organic group]
A repeating structural unit represented by formula (10):

[In Formula (10), G is a tetravalent organic group, and A is a divalent organic group]
In a polyamide-imide containing repeating structural units represented, viewed contains a filler average equivalent circle radius obtained from analysis of the SEM image is 12nm or less, equation (13) more than 30 mole% of G ³ in Is the formula (3)

[In Formula (3), R ^{1 to} R ⁸ each independently represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an aryl group having 6 to 12 carbon atoms, and hydrogen contained in R ^{1 to} R ^8. atoms each independently may be substituted with a halogen atom, B represents a single _{bond, -O -, - CH 2 -} , - CH 2 -CH 2 -, - CH (CH 3) -, - C (CH ₃ ) ₂ —, —C (CF ₃ ) ₂ —, —SO ₂ —, —S—, —CO— or —N (R ⁹ ) — is represented, and R ⁹ is substituted with a hydrogen atom or a halogen atom. Represents an optionally substituted hydrocarbon group having 1 to 12 carbon atoms, n is an integer of 0 to 4, and * represents a bond.
An optical film represented by   The optical film according to claim 3, wherein a circle-equivalent radius of the filler is 1 nm or more. The optical film according to any one of claims 1 to 4 , wherein the haze is 1% or less. The optical film according to any one of claims 1 to 5 , wherein the yellowness is 5 or less. Filler is silica particles, optical film according to any one of claims 1-6. The content of the filler is 60 wt% or less based on the mass of the optical film, the optical film according to any one of claims 1-7. The film thickness is 25 to 100 m, the optical film according to any one of claims 1-8. Comprising an optical film according to any one of claims 1 to 9 flexible image display apparatus. Furthermore, the flexible image display apparatus of Claim 10 containing a polarizing plate. Furthermore, the flexible image display apparatus of Claim 10 or 11 containing a touch sensor.